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Quaestiones

Entomologicae

VOLUME 16

1980

CONTENTS

Perkins - Aquatic beetles of the family Hydraenidae in the Western Hemisphere: classification,

biogeography and inferred phylogeny (Insecta:Coleoptera) 5

Pike - Origin of tundra butterflies in Alberta 555

Halffter, Halffter and Huerta - Mating and nesting behavior of Eurysternus (Coleoptera:

Scarabaeinae) 597

Smith and Lehmkuhl - The larvae of four Hydropsyche species with the checkerboard head

pattern (Trichoptera: Hydropsychidae) .621

Smith and Lehmkuhl - Analysis of*two problematic North American caddisfly species: Oecetis

avara (Banks) and Oecetis disjuncta (Banks) ( Trichoptera : Leptoceridae) . 635

Donald and Mutch - The effect of Hydroelectric dams and sewage on the distribution of

stoneflies (Plecoptera) along the Bow River 657

Smith - Sawflies (Hymenoptera: symphyta) from George Lake, Alberta 671

Book Review-Griffiths, G.C.D. 1980. Flies of the Nearctic Region. 676

Book Review-Howden, H.F. and O.P. Young. 1981. Panamanian Scarabaeinae:Taxonomy,

distribution and habits (Coleoptera, Scarabaeidae). 678

Book Review-Reigert, P.W. 1980. From arsenic to DDT: A history of entomology in western

Canada . 679

Book Review-Matthews, E.G. 1980. A guide to the genera of beetles of South Australia. Part

1. 681

Editor’s acknowldgements 683

Index 685

6 13

Ent

y Quaestiones"

Entomologicae

A periodical record of entomological investigations,

published at the Department of Entomology,

University of Alberta, Edmonton, Canada.

VOLUME 16

NUMBERS 1, 2

JANUARY-APRIL 1980

/

QUAESTIONES ENTOMOLOGICAE

ISSN 0033-5037

A periodical record of entomological investigation published at the Department of

Entomology, University of Alberta, Edmonton, Alberta.

Volume 16

Number 1,2

January 1980

CONTENTS

Perkins - Aquatic beetles of the Family Hydraenidae in the Western Hemisphere:

Classification, Biogeography and Inferred Phylogeny (Insecta:Coleoptera) . . 5

Fig. 1. Dorsal habitus of (clockwise from top left) Hydraena marginieollis , Hydraena cuspidicollis, Spanglerina brevis

and Limnebius alutaceus (not to same scale).

AQUATIC BEETLES OF THE FAMILY HYDRAENIDAE IN THE WESTERN

HEMISPHERE: CLASSIFICATION, BIOGEOGRAPHY AND INFERRED PHYLOGENY

(INSECTA: COLEOPTERA)

PHILIP DON PERKINS

c/o Department of Entomology

National Museum of Natural History

Smithsonian Institution Quaestiones Entomologicae

Washington, D.C. 20560 16:3-554 1980

The aquatic beetle family Hydraenidae in the Western Hemisphere includes nine genera

and 206 species. One genus, Spanglerina (type species S. ingens new species ), is described as

new; two genera, Gymnochthebius and Neochthebius, are elevated from subgeneric rank. New

species (142) are described in the following genera: Hydraenida (1), Parhydraenida (5),

Hydraena (77), Spanglerina (3), Limnebius (11), Gymnochthebius (14), Ochthebius (30) and

Meropathus (1). New synonomies are proposed in Hydraena (1), Limnebius (3),

Gymnochthebius (2) and Ochthebius (7).

Taxonomically and phylogenetically significant structures are illustrated with line

drawings or scanning electron micrographs, and geographical distributions are mapped.

Natural history data are noted for genera and, when available, species. Keys to genera, species

groups, and species are given.

Morphological features unique to the family, including abdominal and aedeagal structure,

are discussed with respect to homologies, and illustrated. Internal reproductive systems of

representative species are illustrated and discussed.

Phylogenetic relationships of the genera are proposed using inferred synapotypic character

states of larvae (external) and adults (external and internal). As a result, a new subfamily,

Ochthebiinae, is proposed, the Hydraeninae is redefined and the Limnebiinae is reduced to

subtribal rank. Geographical distributions of genera and species groups are briefly discussed

with respect to continental drift, global distribution and available fossil data.

Phylogenetic relationships of all species and species groups are presented in phylograms,

together with generalized distribution maps to illustrate repetitive vicariance patterns and

serve as a data base for further studies of historical biogeography. Vicariance zones are

proposed based upon coincident sister-group patterns. North American and some Middle

American vicariance zones are discussed relative to paleogeological events. Based upon

coincidence of vicariance zones and paleogeological events, dichotomies are placed in

mid-Cretaceous, Miocene, Pliocene, and Pleistocene times. Endemism is discussed relative to

vicariance zones.

The following new species are described (type localities parenthetic): Hydraenida robusta

(Maule, Chile); Parhydraenida bubrunipes (Nova Teutonia, Santa Catarina, Brazil),

Parhydraenida hygropetrica (Santa Teresa, Espirito Santo, Brazil), Parhydraenida lambda

(Jaguariaiva, Parana, Brazil), Parhydraenida paralonga (Campos do Jordao, Sao Paulo,

Brazil), Parhydraenida pentatenkta (Portoviejo, Manabi, Ecuador); Spanglerina fluvicola

(Oaxaca, Mexico), Spanglerina frondsicola (Nayarit, Mexico), Spanglerina ingens (Mexico,

Mexico); Limnebius arenicolus (Los Angeles Co., California),

6

Perkins

Limnebius aridus ( Hidalgo Co., New Mexico), Limnebius borealis ( British Columbia,

Canada ), Limnebius leechi ( Mendocino Co., California), Limnebius mexicanus ( Oaxaca ,

Mexico), Limnebius mitus ( Zacatecas , Mexico), Limnebius octolaevis (Totonicapan,

Guatemala), Limnebius ozapalachicus ( Bath Co., Virginia), Limnebius richmondi (Lewis Co.,

New York), Limnebius texanus (Culberson Co., Texas), Limnebius utahensis (Wasatch Mts.,

Utah); Gymnochthebius bartyrae (Lima, Peru), Gymnochthebius bisagittatus (Cundinamarca,

Colombia), Gymnochthebius clandestinus (Maule, Chile), Gymnochthebius compactus

(Parana, Brazil), Gymnochthebius curvus (Valdivia, Chile), Gymnochthebius falli (Logan Co.,

Kansas), Gymnochthebius maureenae (George Co., Mississippi), Gymnochthebius octonarius

(Tucuman, Argentina), Gymnochthebius oppositus (Baja California, Mexico),

Gymnochthebius perlabidus (Limon, Costa Rica), Gymnochthebius plesiotypus (Concepcion

region, Chile), Gymnochthebius reticulatissimus (Tucuman, Argentina), Gymnochthebius

seminole (Monroe Co., Florida), Gymnochthebius tectus (Maule, Chile); Meropathus vectis

(Isla de los Estados, Argentina).

New species of Ochthebius are: Ochthebius alpinopetrus (Natrona Co., Wyoming),

Ochthebius angularidus (Coahuila, Mexico), Ochthebius apache (Cochise Co, Arizona),

Ochthebius arenicolus (Colusa Co., California), Ochthebius arizonicus (Gila Co., Arizona),

Ochthebius biincisus (Monterey Co., California), Ochthebius bisinuatus (Trinity Co.,

California), Ochthebius borealis (Glenn Co., California ), Ochthebius brevipennis (Tillamook

Co., Oregon), Ochthebius browni (Mexico, Mexico), Ochthebius californicus (Tulare Co.,

California), Ochthebius crassalus (Ventura Co., California), Ochthebius gruwelli (Baja

California, Mexico), Ochthebius hibernus (Oregon), Ochthebius lecontei (British Columbia,

Canada), Ochthebius madrensis (Cochise Co., Arizona), Ochthebius mesoamericanus (Jalapa,

Guatemala), Ochthebius mexicanus (Mexico, Mexico), Ochthebius mexcavatus (Durango,

Mexico), Ochthebius orbus (Marin Co., California), Ochthebius pacificus (Sonoma Co.,

California), Ochthebius pauli (Oaxaca, Mexico), Ochthebius recticulus (Colusa Co.,

California), Ochthebius rectusalsus (Contra Costa Co., California), Ochthebius reticulocostus

(Mexico, Mexico), Ochthebius richmondi (Humboldt Co., California), Ochthebius sculptoides

(Ventura Co., California), Ochthebius sierrensis (Fresno Co., California), Ochthebius tubus

(Baja California, Mexico), Ochthebius uniformis (San Francisco Co., California).

New species of Hydraena are: Hydraena alternata (Durango, Mexico), Hydraena alterra

(Minas Gerais, Brazil), Hydraena anaphora (Matto Grosso, Brazil), Hydraena ancylis (York

Co., Pennsylvania), Hydraena anisonycha (Cundinamarca, Colombia), Hydraena

appalachicola (Bath Co., Virginia), Hydraena arenicola (Lake Co., California), Hydraena

arizonica (Santa Cruz Co., Arizona), Hydraena argutipes (Durango, Mexico), Hydraena

atlantica (Montgomery Co., Maryland), Hydraena barricula (Chiapas, Mexico), Hydraena

bituberculata (Cochise Co., Arizona), Hydraena bractea (Durango, Mexico), Hydraena

bractoides (Durango, Mexico), Hydraena breedlovei (Durango, Mexico), Hydraena browni

(Guarico, Venezuela), Hydraena californica (Marin Co., California), Hydraena campbelli

(Chiapas, Mexico ), Hydraena canticacollis (Zacatecas, Mexico), Hydraena chiapa (Chiapas,

Mexico), Hydraena circulata (Butte Co., California ), Hydraena colombiana (Cundinamarca,

Colombia), Hydraena colymba (Jalapa, Guatemala), Hydraena costiniceps (Salta, Argentina),

Hydraena crystallina (Jalisco, Mexico), Hydraena cuspidicollis (Oaxaca, Mexico), Hydraena

d-destina (Chiapas, Mexico), Hydraena exilipes (Tamaulipas, Mexico), Hydraena geminya

(Oaxaca, Mexico), Hydraena guatemala (Escuintla, Guatemala), Hydraena haitensis (Etang

Lachaux, Haiti), Hydraena hyalina (Guarico, Venezuela ), Hydraena jivaro (Napo, Ecuador ),

Western Hemisphere Hydraenidae

7

Hydraena leechi ( Coconino Co., Arizona), Hydraena limpidicollis ( Canal Zone, Panama),

Hydraena malkini (Tres Rios, Costa Rica), Hydraena maureenae (Bath Co., Virginia),

Hydraena mazamitla ( Jalisco , Mexico), Hydraena mexicana (Chiapas, Mexico), Hydraena

mignymixys (Lake Co., California), Hydraena nevermanni (Reventazon, Costa Rica),

Hydraena newtoni (Canal Zone, Panama), Hydraena oaxaca (Oaxaca, Mexico), Hydraena

oblio (Baja Verapaz, Guatemala), Hydraena occidentalis (Mendocino Co., California),

Hydraena orcula (Goias, Brazil), Hydraena ozarkensis (McDonald Co., Missouri), Hydraena

pacifica (British Columbia, Canada), Hydraena paeminosa (Zanderij, Surinam ), Hydraena

particeps (Guarico, Venezuela), Hydraena pavicula (Lima, Peru), Hydraena peru (Huanuco,

Peru), Hydraena petila (Tehama Co., California), Hydraena pontequula (Canal Zone,

Panama), Hydraena premordica (Mayaro, Trinidad), Hydraena prieto (Durango, Mexico),

Hydraena pulsatrix (Tamaulipas, Mexico ), Hydraena quadricurvipes (Chattooga Co.,

Georgia), Hydraena quechua (Los Rios, Ecuador), Hydraena sabella (Chiapas, Mexico),

Hydraena scintilla (Oaxaca, Mexico), Hydraena scintillabella (Cundinamarca, Colombia),

Hydraena scintillutea (Minas Gerais, Brazil), Hydraena scolops (Mexico, Mexico), Hydraena

scopula (Jalisco, Mexico), Hydraena sierra (Madera Co., California), Hydraena spangleri

(Montgomery Co., Maryland), Hydraena splecoma (Chiapas, Mexico), Hydraena terralta

(Minas Gerais, Brazil ), Hydraena trinidensis (St. Augustine, Trinidad), Hydraena tucumanica

(Tucuman, Argentina), Hydraena tuolumne (Tuolumne Co., California), Hydraena turrialba

(Turrialba, Costa Rica), Hydraena vela (Nayarit, Mexico), Hydraena yosemitensis (Mariposa

Co., California), Hydraena youngi (Alachua Co., Florida), Hydraena zapatina (Jalisco,

Mexico).

The following new synonymies are proposed (junior names parenthetic): Limnebius

alutaceus (Casey) (L. columbianus Brown, L. congener Casey), L. angustulus (Casey) (L.

coniciventris (Casey)); Gymnochthebius fossatus (LeConte) (G. nitiduloides (d’Orchymont), G.

parvulus (Sharp)); Ochthebius interruptus LeConte (O. aberti Hatch), O. aztecus Sharp (O.

bruesi Darlington), O. marinus (Paykull) (O. holmbergi Maklin), O. discretus LeConte (O.

insulanus Brown), O. lineatus LeConte (O. milleri Hatch), Ochthebius attritus LeConte (O.

schubarti d’Orchymont), Ochthebius similis Sharp (O. wickhami Fall); Hydraena punctata

LeConte (H. needhami d’Orchymont ).

La famille de coleopteres aquatiques des Hydraenidae compte, dans I’hemisph'ere ouest, neuf genres et 206 especes.

Un genre nouveau. Spanglerina (espece type, S. ingens, especes nouveau ). est decrit; les sous-genres Gymnochthebius et

Neochthebius sont eleves au rang de genre. Un total de 142 especes nouvelles sont decrites dans les genres suivants:

Hydraenida (I), Parhydraenida (5), Hydraena (77). Spanglerina (3), Limnebius (II), Gymnochthebius (14), Ochthebius

(30) et Meropathus ( I ). De nouveaux synonymes sont proposes dans les genres Hydraena (1), Limnebius (3),

Gymnochthebius (2) et Ochthebius (7).

Les structures d’une importance taxonomique et phylogenetique particuliere sont illustrees par des dessins ou des

photos prises au microscope a balayage electronique; la repartition geographique des taxons est presentee sur des cartes.

Les donnees d'histoire naturelle sont presentees pour chaque genre et, lorsque disponibles, pour les especes. Des cles

d’ identification sont fournies pour les genres, les groupes d’especes et les especes.

Les caracteres morphologiques uniques a la famille sont illustres et discutes en relation avec leurs homologues, et

incluent des structures de V abdomen et de I’edeage. Les parties internes du systeme reproducteur d’especes

representatives sont illustrees et discutees.

Les relations phylogenetiques des genres sont etablies a partir de synapotypies des larves (caracteres externes

seulement) et des adultes (caracteres externes et internes). En consequence, une nouvelle sous-famille, celle des

Quaest. Ent., 1980, 16 (1,2)

8

Perkins

Ochthebiinae, est proposee, les Hydraeninae sont redefinis et les Limnebiinae sont abaisses an rang de sous-tribu. La

repartition geographique des genres et des groupes d'especes est brievement discutee en relation avec la derive des

continents, la distribution globale de la famille et les fossiles disponibles.

Les relations phylogenetiques de toutes les especes et de tous les groupes d’especes sont illustrees par des

phylogrammes; a celles-ci sont adjointes des cartes illustrant les distributions generalises, qui montrent les patrons

repetitifs de vicariance et qui pourront servir de donnees de base pour des etudes eventuelles sur la biogeographie

historique. Les zones de vicariance sont determinees a partir des distributions co'incidentes de groupes apparentes. Les

zones de vicariance de I’Amerique du Nord et de I’Amerique Centrale sont discutees en rapport avec des evenements

paleontologiques. Suivant la coincidence des zones de vicariance et les evenements paleontologiques qui leur sont

associes, les dichotomies devraient dater du Cretace Moyen, du Miocene, du Pliocene et du Pleistocene. Les cas

d’endemisme sont interprets en rapport avec les zones de vicariance.

Les noms des especes nouvelles (ainsi que les localites types) sont enumer&s dans le resume anglais.

TABLE OF CONTENTS

Introduction 8

Natural History 11

Criteria for Species Level Taxa 13

Methods and Materials . . 14

Morphological Analysis 15

Key to Genera of Western Hemisphere Hydraenidae 34

Checklist of Western Hemisphere Hydraenidae 36

Genus Hydraenida Germain 40

Genus Parhydraenida J. Balfour-Browne 45

Genus Hydraena Kugelann 60

Genus Spanglerina, new genus 212

Genus Limnebius Leach 222

Genus Gymnochthebius d’Orchymont 244

Genus Ochthebius Leach 292

Genus Meropathus Enderlein 406

Genus Neochthebius d’Orchymont 408

Phylogenetic Relationships and Zoogeography 410

Epilogue 481

Appendix A: Paratypes and Material Examined 482

Appendix B: Tabulary Summary 525

Acknowledgements 536

References 537

Index 544

INTRODUCTION

Adults of Hydraenidae are minute aquatic beetles, most of which are slightly less than

2.00 mm long and found at the margins of aquatic habitats, especially streams. They have been

Western Hemisphere Hydraenidae

9

termed “minute moss beetles” by some, but in actuality a very small percentage of species are

associated with moss. Most species live in sandy or gravelly aquatic situations, therefore, a

more appropriate common name for the family might be “micropsammophilous aquatic

beetles”.

Generalities regarding the habits of the family are difficult to make since, as in any

consideration of a rather large evolutionary unit, exceptions abound. Hence, various kinds of

hydraenid beetles live in such diverse aquatic habitats as hot springs, cold mountain streams,

rapid tropical cascades, saline beach pools, cracks in rocks covered at high tide, and vertical

rock faces in hygropetric habitats.

Although the family is relatively small in most respects, including size of individuals,

number of species and generic diversity, from an evolutionary and biogeographic viewpoint it is

one of the most interesting members of the series Staphyliniformia. Hydraenids have a curious

combination of characters and habits which have resulted in their placement with the primitive

Staphylinoidea by some authors, and with the Hydrophiloidea by others.

The family has not been studied in a collective, monographic manner, and none of the

Western Hemisphere genera have been treated in a modern, revisionary context. Most

descriptions of Western Hemisphere species are scattered throughout the literature, and

illustrations of taxonomically important structures are the exception.

This study stems from an earlier investigation in which I attempted to elucidate taxonomic

characters to differentiate larvae of a few species of hydraenids in southern California.

Although I was able to rear larvae and therefore definitely associate the adult and larval forms

of a species, it soon became apparent that taxonomic literature on the adults was quite

inadequate. Consequently, although differentiating characters were found for the larvae, the

taxa they represented remained problematic. This work will correct that situation, and,

hopefully, provide a stimulus and stable basis for future studies on the immature stages.

The family Hydraenidae was first proposed by d’Orchymont (1919) based upon criteria he

had presented previously (1916). These criteria included some considerations of both larval and

adult structures, and resulted in the organization of the included taxa in three subfamilies:

Hydraeninae, Limnebiinae, and Spercheinae. These three groups had originally been placed in

the Hydrophilidae.

Twelve years later, Boving and Craighead (1931) published their extensive work on the

larvae of Coleoptera, in which they concluded that the genera Limnebius , Hydraena and

Ochthebius constituted a family in the “leptinid association” of the Staphylinoidea, and

proposed the name Limnebiidae, whereas Spercheus was afforded familial rank within the

Hydrophiloidea. Apparently Boving and Craighead were unaware of d’Orchymont’s previous

work.

Leech (1948) was the first American entomologist to point out that d’Orchymont’s name

Hydraenidae was published prior to Boving and Craighead’s Limnebiidae; he also indicated

that the name may be credited to Mulsant (1844). Leech (1948) states, “Judging from the

recent work of students in other orders of insects, and their interpretation of the International

Rules and of Opinion 133, the name Limnebiidae should be credited not to Boving but to

Mulsant who proposed it as ’Limnebiaires’ (1844: 88). On the other hand, the name

Hydraenidae has been in use for many years by d’Orchymont, and perhaps should take

precedence. It too may be credited to Mulsant (1844: 27), based on his ‘Hydraenaires’.”

Later, Leech (in Leech and Chandler, 1956) used the name Hydraenidae in his review of

the United States genera and California species. Nevertheless, during the 1960’s the incorrect

Quaest. Ent., 1980, 16 (1,2)

10

Perkins

name Limnebiidae continued to appear in general works by American authors (e.g., Borror and

DeLong, 1964; Arnett, 1968). More recent works by American authors (e.g., Doyen and

Ulrich, 1978) use the name Hydraenidae, and the name has been in use by European authors

since it was proposed by d’Orchymont (1919).

LIST OF ABBREVIATIONS

The following abbreviations in the text indicate collections from which material was

borrowed and the repository of specimens.

AFN

AG

AMNH

ASP

BMNH

CAS

CCW

CFMNH

CMP

CNC

CSQ

CU

DCM

DPW

EJK

FNY

GWF

HM

HNHM

HPB

INHS

IOJ

ISNB

ISU

JEC

JFB

JLC

JLH

JS

KS

LACM

LSU

MCZ

MHNC

MSP

MU

NDSU

NMD

NYSS

ODA

ORSU

OSU

PBPI

PDP

PM

PMNH

PU

A.F. Newton, Jr., Museum of Comparative Zoology, Flarvard University, Cambridge, Massachusetts

A. Gillogly, Fort Baker, California

L.H. Herman, American Museum of Natural History, New York

Academy of Natural Sciences, Philadelphia

P. Hammond, M.E. Bacchus, British Museum (Natural History), London

H.B. Leech, D.H. Kavanaugh, California Academy of Sciences, San Francisco

W.R. Suter, Carthage College, Wisconsin

H. Dybas, Field Museum of Natural History, Chicago

G. Wallace, Carnegie Museum, Pittsburgh

A. Smetana, Canadian National Collection, Ottawa

R. Beique, Complexe scientifique du Quebec

L. L. Pechuman, Cornell University, New York

D. C. Miller, City College of New York

C.P. Wooldridge, Pennsylvania State University, University Park, Pennsylvania

E. J. Kiteley, Quebec

F. N. Young, Univeristy of Indiana, Bloomington, Indiana

G. W. Folkerts, Auburn University, Auburn, Alabama

H. Silfverberg, Helsinki Museum

Z. Kaszab, Hungarian Natural History Museum, Budapest

Harley f\ Brown, University of Oklahoma, Norman, Oklahoma

M. W. Sanderson, Illinois Natural History Survey

T.H. Farr, Science Museum, Institute of Jamaica, Kingston

E. Janssens, G. Demoulin, Institut royal des Sciences Naturelles de Belgique, Brussels

R.E. Lewis, Iowa State University, Ames, Iowa

J.E. Cronin, California

J.F. Brimley, Wellington, Ontario

J.L. Carr, Calgary, Alberta

J.L. Heilman, University of Maryland, College Park, Maryland

J. Schuh Klamath Falls, Oregon

Karl Stephan, Tucson, Arizona

C.L. Hogue, Los Angeles County Museum

J.B. Chapin, Louisiana State University, Baton Rouge, Louisiana

J. Scott, A. Newton, M. Thayer, Museum of Comparative Zoology, Harvard University, Cambridge,

Massachusetts

A. Camousseight, Museo Nacional de Historia Naturale, Santiago, Chile

Hans Reichardt, Cleide Costa, Museu de Zoologia da University de Sao Paulo

V.R. Vickery, McGill University, Montreal, Quebec

R.L. Post, A. Ashworth, North Dakota State University, Fargo, North Dakota

N. M. Downie, Lafayette, Indiana

R.E. Kurczewski, State University of New York, Syracuse

R.L. Westcott, Oregon Department of Agriculture, Salem, Oregon

L. Ryker, Oregon State University, Corvallis, Oregon

C.A. Triplehorn, Ohio State University, Columbus, Ohio

K. R. Valley, Pennsylvania Bureau of Plant Industry

P.D. Perkins, National Museum of Natural History, Washington, D.C.

J. Menier, Museum National d'Historie Naturelle, Paris, France

K. W. Brown, Peabody Museum of Natural History, Connecticut

A. Provonsha, Purdue University, Lafayette, Indiana

Western Hemisphere Hydraenidae

11

RG R. Gordon, Washington, D.C.

RTA R.T. Allen, University of Arkansas, Fayetteville

SC St. Cloud State College, Minnesota

SDSU E.U. Balsbaugh, Jr., South Dakota State University

Sll Staten Island Institute of Arts and Sciences, New York

UA F.G. Werner, University of Arizona, Tucson, Arizona

UBC K.M. Stuart, University of British Columbia, Vancouver

UCB J.A. Chemsak, University of California, Berkeley

UCD R.O. Schuster, University of California, Davis

UCR S. Frommer, University of California, Riverside

UCM U.N. Lanham, University of Colorado Museum, Boulder

UI University of Idaho, Moscow, Idaho

UM M. Coulloudon, University of Montreal, Montreal

UMA P.J. Clausen, University of Minnesota, Minneapolis, Minnesota

UM1 T.E. Moore, University of Michigan, Ann Arbor, Michigan

UNH University of New Flampshire, Durham, New Flampshire

USNM P.J. Spangler, National Museum of Natural History, Washington, D.C.

UW L.J. Bayer, University of Wisconsin, Madison, Wisconsin

UWA S. Rohwer, University of Washington, Seattle, Washington

VMK V.M. Kirk, South Dakota Insect Laboratory

WRS Walter R. Suter, Carthage College, Wisconsin

WSUP W.J. Turner, Washington State University, Pullman.

NATURAL HISTORY

Members of the family Hydraenidae in the Western Hemisphere are most frequently found

at the margins of clear, sandy streams (Figs. 191A,192A). In such habitats they are easily

collected by stirring the sand and gravel at the waterline and waiting for the beetles to float to

the surface, where they remain suspended, upside-down, in the surface film. Since they cannot

swim, these tiny beetles become trapped in the surface film, appearing as silvery specks due to

their ventral air bubble. While in this inverted position, a beetle is able to walk about on the

underside of the surface film, and when near an emergent object the floating beetle is

immediately pulled to the object by surface tension, and rapidly crawls beneath the surface.

In streams of western North America one can frequently find Hydraena, Ochthebius and

Limnebius adults in microsympatry with adults of such hydrophilid genera as Laccobius and

Chaetarthria. Elsewhere (Perkins, 1976) I described a sampling technique which can be used

to study the different microhabitat zones used by these psammophilous aquatic beetles, and

factors which limit their microhabitat distributions. I refer the reader to that paper for details

on this topic, and restrict my comments to more generalized aspects of habitat use by

hydraenids.

Generally speaking, the adaptation of species to margins of lentic habitats, such as ponds,

lakes and rock pools, sees its greatest expression in Ochthebius and allied genera, a decidedly

smaller percentage of Hydraena species being typical of such habitats, whereas New World

Limnebius species are known only from flowing water. Ochthebius is also the only genus of

these three which has species adapted to margins of saline and alkaline aquatic habitats, such

as salt marshes and mineralized hot springs.

Certain other genera are quite specialized in their use of aquatic habitats. Neochthebius

adults are found only in cracks and crevices of intertidal rocks (Figs. 198A-C), whereas

Parhydraenida adults are madicolous and Spanglerina adults live on plant debris trapped

behind emergent rocks in rapid tropical streams (Figs. 196A,B).

Quaest. Ent., 1980, 16 (1,2)

12

Perkins

Although members of Hydraenidae in the Western Hemisphere are less frequently collected

than those of many other families of aquatic insects, they are extremely abundant locally if the

physical conditions are appropriate (e.g., Hydraena anisonycha, Ochthebius attritus,

Limnebius ozapalachicus, among others).

Where along a drainage system hydraenids live, and densities attained by the localized

populations, are determined to a large extent by particle and interstitial space size of shoreline

substrate; if particle size is too small, and consequently also interstitial space size, such as in

muddy areas (or silty streams), hydraenids will usually not be present. Conversely, if the

shoreline substrate consists of large stones and boulders, a few specimens of hydraenids may be

found, but not dense populations (an exception to this statement are those species well adapted

to lentic habitats, such as potholes, which can develop dense populations when conditions are

favorable).

Population densities are also intimately related to slope and permanence of the stream bank

(Perkins, 1976). Relatively permanent streambanks with well sorted particles provide living

space and permanence necessary for larvae to complete their development. Larvae have thin

cuticles, requiring that they be in moist situations. However, hydraenid larvae are not aquatic

in the strict sense, and drown if kept beneath the water’s surface for extended periods. Their

small size makes even a drop of water potentially dangerous in the proper circumstances.

Slope of a streambank, its permanence, and degree of saturation of the psammic zone are all

intimately related. Relatively saturated banks generally have a much lower slope angle and are

much more frequently washed downstream and redeposited, whereas relatively unsaturated

banks are generally much more permanent and have a higher slope angle. Frequent mixing of

particles in the relatively saturated and impermanent banks results in more uniform particle

size and prevents vertical sorting of particles. Relatively permanent banks, however, do not

have the particles mixed frequently and the banks are high enough above the water level of the

stream to allow percolation of rain water and water splashing from the stream, with the

consequent sorting of particles (Perkins, 1976). Along streams and creeks with relatively

permanent, sandy shorelines high population densities of hydraenids are usually encountered

(again, these generalizations do not pertain to species typical of standing water).

My experiences collecting in Mexico and Central America revealed habitat preferences

which were quite unexpected. Specimens of a few hydraenids, including all species of

Spanglerina, were found almost exclusively on leaves and twigs which had become trapped

behind stones in rapid tropical streams and cascades (Figs. 196A,B).

These tropical streams typically have a fast flow rate and lack relatively permanent

sand-gravel banks of moderate slope angle and consisting of well sorted particles. Instead, these

rapid tropical streams generally have large boulders behind which first limbs then leaves and

twigs of the plentiful tropical vegetation become trapped.

Two species of Hydraena have also been found in these Spanglerina type habitats,

Hydraena cuspidicollis and Hydraena geminya, as I have collected the former in association

with Spanglerina ingens and the latter with Spanglerina brevis The common habitat of

Hydraena geminya and Spanglerina perhaps explains the widely separated pro- and mesocoxae

of adults of Hydraena geminya and of the other two species of Hydraena closely related to it

(geminya Subgroup). One of the distinctive characteristics of Spanglerina adults is the widely

spread coxae (Figs. 63A,65B) which, as in the Elmidae, are probably an adaptation to allow the

beetles to cling tightly to leaves and twigs in habitats where water flows rapidly.

Data on the immature stages of Hydraenidae, other than that presented in the section on

Western Hemisphere Hydraenidae

13

phylogeny, will be published separately. More specific natural history data pertaining to adults,

when available, is presented in the individual species sections.

CRITERIA FOR SPECIES LEVEL TAXA

The common notion of reproductive isolation is central to the biological species concept,

which I accept (see Mayr, 1969). In practice, determination of reproductive isolation in most

groups is based almost entirely upon indirect, anatomical evidence. Therefore, although it is

possible to demonstrate reproductive isolation, in actuality it is inferred in most taxonomic

work. However, anatomical features upon which inferences are based when predicting species

limits differ markedly from those used in phylogeny reconstruction in that autapomorphous

characters (unique to a species), which do not provide information for phylogeny

reconstruction, are the primary basis for inferring reproductive isolation. Conversely,

synapomorphic (see Hennig, 1966) anatomical features are most useful in phylogeny

reconstruction, but of little aid when attempting to determine species limits.

In most insect groups, including the Hydraenidae, the taxonomist is provided with a

powerful tool of species limits inference in the male genitalia. In Hydraenidae the aedeagus

provides the single most dependable structure upon which to base species level inferences.

Consequently, I have placed a great deal of emphasis upon this structure and am confident it

justifies the “weighting” it has been given. I have made an attempt, when possible, to not only

display the aedeagal differences between species, but also indicate infraspecific aedeagal

variation (e.g., Figs. 91 A-F, 104,1 13A, etc.). After examination of the adeagus in excess of

5200 males, I am confident of the diagnostic importance of this structure. Other external

characteristics are important and they have been carefully studied and described in detail.

However, the most important features in determining closely related sister-species are provided

by the aedeagus.

Because of the highly diagnostic nature of the male genitalia, I have refrained almost

entirely from describing new species when males were not available. Thus, of the 142 new

species described herein, only four of these are known at present from female specimens alone.

These four species are very distinct externally and have been described because they contribute

significantly to our knowledge of either generic distributions ( Meropathus vectis,

Parhydraenida pentatenkta) or species group phylogeny ( Gymnochthebius maureenae,

Gymnochthebius perlabidus ). Additional species in the genera Parhydraenida , Hydraena,

Ochthebius and Gymnochthebius are apparent in the material studied, but I prefer to await

capture of males before describing these species.

For supraspecific categories, subgenera are recognized only for Ochthebius (see

classification section for rationale). Other aggregates of species (below the generic level) are

ranked in informal categories of “species group”, “species subgroup” or “species complex”. As

is discussed in the classification sections on Hydraena and Ochthebius , subgeneric taxa

recognized by earlier workers are generally found to be linked to one another by transitional

stages, and hence, in this family at least, serve principally to burden the nomenclature.

Quaest. Ent., 1980, 16 (1,2)

14

Perkins

METHODS AND MATERIALS

I have examined more than 21,250 adult New World hydraenids plus a significant number

of specimens from other regions of the globe during this study (see Appendix B). Of the New

World specimens, more than 5,218 males were dissected to remove the aedeagus, and numerous

females were dissected to remove the spermatheca (see following section). To attach beetles to

paper “points”, I used common fingernail polish which dissolves with amyl acetate or fingernail

polish remover. A “Wild M5” stereomicroscope was used throughout the study, and

measurements were made with an ocular micrometer fitted to the microscope.

Dissecting techniques

The aedeagus of hydraenid beetles is best removed by opening the elytra and making an

incision along one side in the tergal-sternal membrane from the fourth to the sixth segments,

plus severing the intersegmental membranes between the third and fourth and between the

sixth and seventh terga. The flap of terga thus formed is then laid back, exposing the abdominal

contents, and the aedeagus is extracted with a fine probe. Once the aedeagus has been removed,

the flap of terga is replaced and the elytra returned to the closed position.

For study of the gut and internal reproductive system, it is generally necessary to remove the

elytra entirely, then make an incision along the length of the pleural membrane so that all of

the terga may be lifted. The gut is severed where it enters the abdominal cavity, and the

intersegmental membrane between the fifth and sixth sterna is ruptured, allowing the

abdominal cavity contents to be removed intact.

Once removed, aedeagus and/or abdominal contents are transferred to glycerin from the

water or alcohol in which the dissections were made. For adeagi dissected in alcohol, the

transfer must be made very rapidly so that partial drying does not occur. Drying allows the

formation of air pockets, which in turn obscure internal structure. Once the sclerites are in

glycerin, this is no longer a problem because of the low evaporative rate.

For storage, aedeagi were placed in a tiny drop of glycerin inside a small glass vial which is

cork stoppered. The vial is then affixed to the pin by inserting the pin through the cork, and the

vial is oriented so that the aedeagus is visible through the upper surface of the vial when the

beetle is being studied. Storage in a vial not only provides protection for the aedeagus, but also

affords a degree of protection for the beetle since some of the glass vial projects slightly beyond

the beetle.

I view the method used by d’Orchymont and some others of gluing the aedeagus by its base

to the corner of the card upon which the beetle is also glued as improper since it places this

singularly important structure in a very precarious position. Additionally, it allows the

aedeagus to dry which makes it very brittle and further subject to damage.

Equally improper is the preparation of permanent slide mounts of aedeagi in this group.

This treatment forces the apical portion to be twisted from its proper place in relation to

surrounding surfaces, resulting also in distortion of the midregion. In addition, oval structures

are flattened, the aedeagus is seen in only one view, and the microslide must be placed in a

collection separate from the beetle, thereby increasing the probability of loss. The results of

distortion by microslide mounting are apparent in the illustration of the aedeagus of Hydraena

insularis d’Orchymont (Fig. 53D). Ochthebius kaszabi Janssens is an example of the problems

that can develop when the holotype aedeagus is slide mounted.

Western Hemisphere Hydraenidae

15

Illustrations

All drawings were made by me. Aedeagi were drawn with the aid of a microprojector, which

presents the specimen’s exact image. Highly asymmetrical structures such as the aedeagi of

hydraenids must be illustrated in two views to allow adequate conceptualization of contours.

Consequently, all of the aedeagal illustrations were made in two views, one dorsal and one of

the left lateral aspect. Additionally, partial drawings were made when slight rotation of the

apical portion provides significant additional information.

The more complex aedeagi of Hydraena, and portions of aedeagi of other genera where

contours are especially well developed and important, are stippled in an attempt to reveal these

contours and internal structures.

All aedeagi are at the same scale to make comparison easy. Representative scale lines are

given for most genera (Figs. 13,18,19,22,72,84,100,138,144). Likewise, all body outline

illustrations, drawn with a camera lucida mounted to the microscope, are at the same scale.

Internal reproductive structures were also drawn with the aid of a microprojector.

MORPHOLOGICAL ANALYSIS

Certain morphological features of various genera in the family are worthy of special

comparative discussion, which is presented here. Morphological features used in the taxonomic

treatment are not treated in detail here, but are discussed and illustrated within each generic

unit under the “Discussion” and “Pronotal features” sections.

Sexual dimorphism

Sexual differences are expressed in several external morphological trends within the family.

Because of the highly diagnostic nature of the male genitalia, these sexual differences assume a

significant practical importance since they permit ready recognition of males.

The apex of the abdomen differs between sexes in all species: males with the last sternum

narrower and the penultimate tergum “wrapped around” the sides of the abdomen so that this

tergum is readily visible from ventral view (Figs. 3A,B,63D); females have the last sternum

broader and the penultimate tergum not wrapped around to the extent seen in males

(Figs. 3D,35C). In addition, males of certain species have the last abdominal segments

elongate, this applies primarily to species of the leechi and marginicollis Groups of Hydraena

(Figs. 54B,63B). However, since males of many species do not have elongate segments, and

because the last sternum and part of the last tergum are concealed in some individuals due to

contraction (Figs. 63A,C), it is convenient to have recourse to other sexual differentiating

structures.

Females of Hydraena and Spanglerina have a row of long setae across the anterior portion

of the fifth abdominal sternum (Figs. 35C,48B); this fringe probably functions to prevent

collapse of the ventral air bubble during oviposition. Males have sparse, random, shorter setae

on this sternum (Figs. 63A-D).

Males of many species of Hydraena and Spanglerina (but not including the circulata Group

of Hydraena other than Hydraena quadricurvipes), have distinctive modifications of the pro-

and metatibiae which take a great many forms, some of which are species specific. Protibiae

are excavated near the apex (Figs. 54G,H) or are swollen in many shapes on the inner surface

(Figs. 61C,D,G,H). The metatibiae of some males are enlarged

Quaest. Ent., 1980, 16 (1,2)

16

Perkins

i

Figs. 2A - F (A) diagrammatic representation of abdominal sclerites of Hydraena d-destina <3. (B) aedeagus, homologues

of sterna 9 and 10 and associated muscles of Ochthebius puncticollis. (C) ventral view of terga 9 and 10 (numbered to left)

and sterna (numbered to right) of Hydraena anisonycha. (D) sterna 9 and 10 and associated membrane of Ochthebius

puncticollis. (E) as above, Hydraena anisonycha. (F) hypothetical hydraenid aedeagus.

(Figs. 32D-G,57C,E,F,61A,B,E,F), or have distinctive “brushes” of setae which are stiff and

therefore do not lie flat against the leg in dry specimens (Figs. 32D-G). The extensive variation

in form of the metatibiae suggests a high mutation rate for genes controlling this structure.

Indeed, the only obvious deformity I have seen in the many specimens of Hydraena studied was

a bifurcate metatibia in Hydraena pontequula (Fig. 63D).

Among the more unusual sexual differences in Hydraena are the highly asymmetrical

middle claws of Hydraena anisonycha males (Fig. 57D) and the stridulatory ridges on the

occiptial area of the head in males of the leechi Group (Fig. 3 ID) (discussed in a later section).

In sharp contrast to Hydraena , males of Ochthebius, Gymnochthebius and related genera do

not display obvious differences in tibiae between sexes and females do not have the distinctive

row of long setae on the fifth abdominal sternum. Instead, males of Ochthebius generally (but

not invariably) have distinctive suction setae on protarsal segments (Figs. 98C,128E).

Additionally, males of many species of Ochthebius and Gymnochthebius have the anterior

margin of the labrum upturned and emarginate. Within the emargination are sensilla of various

shapes, generally trumpet-shaped or spatuliform (Figs. 98B,D,103F,1 1 1 A,1 15B,128D,F).

Females also have these sensilla, but they are less developed and the labral margins are not

Western Hemisphere Hydraenidae

17

upturned at all or to the extent seen in males. The greater development of these sensilla in

males (plus upturned margin which would presumably allow them to be placed closer to. the

object sensed) suggest that they may, at least in part, serve for mate recognition.

Males of Gymnochthebius species have two distinctive, longitudinal rows of setae on the last

abdominal sternum.

Males of many Meropathus species have the labrum extended anteriorly into two

remarkably long processes (e.g., M. campbellensis). The only Western Hemisphere species ( M .

vectis ) is known only from females, but males are expected to possess these processes.

Hydraenida males are easily recognized by large pads of protarsal suction setae.

Parhydraenida males, however, lack these pads of suction setae, but many have the labrum

strongly upturned (Figs. 15B-D) and the abdominal differences between sexes described above

generally are obvious.

Limnebius males are easily differentiated, possessing large pads of suction setae on the pro-

and mesotarsi (Fig. 69C). Additionally, males generally have the elytral apices truncate

slightly, and frequently have a median oval depression on the sixth abdominal sternum.

Aedeagus

In most species of hydraenids the aedeagus is a tubular structure, more or less curved at the

base and has two lateral parameres (Figs. 2F,22A-E,60A-D). It differs from the typical four

lobed (basal piece + median lobe + two parameres) aedeagus of most polyphagan males in

that it lacks (in many species) an obvious, distinct demarcation between basal piece and median

lobe.

Lack of a distinctive demarcation between basal piece and median lobe has prompted some

authors to postulate that the basal piece, as such, is absent from Hydraenidae, and therefore

the entire aedeagus, with the exception of the parameres, consists of a structure homologous to

the median lobe of other beetles. Thus, Crowson (1955) states, “Not the least remarkable

feature of these perplexing insects is their abdominal structure. Assuming that, as is general in

Haplogastran beetles, the first complete visible sternite belongs to the third abdominal segment

and that the second is represented only by lateral pleural vestiges and perhaps some trace in the

middle between the hind coxae, the adult in both sexes would appear to have complete tergites

and sternites up to and including the ninth segment and a distinct tergite for the tenth. The

presence of a distinct ninth sternite seems here, as in the Staphylinidae, to be correlated with

the absence of a basal piece of the aedeagus; in fact it seems quite possible that the basal piece

of the aedeagus is the ninth sternite”.

Specialists in the Hydraenidae, however, have contended that the main tube of the aedeagus

actually represents the basal piece and that the structure at the apex of this heavily sclerotized

tube is homologous to the median lobe of the plesiomorphic state. This terminal structure is

frequently movable (mobile) and structurally very complex. D’Orchymont (1929c) was

apparently the first to present this view, as he compared the hydraenid aedeagus to that of the

hydrophilid, Spercheus : “II se compose d’une partie rigide et fortemont sclerifiee en form de

coin, de forme tres variee, ordinairement en courbe plus or moins prononcee dont la concavite es

dorsale. C’est l’equivalent du lobe basal des Spercheus et des Hydrophilidae ( sensu stricto ); de

a lobe basal a une certain distance de sa base et avant son extreemite se detache a droite un lobe

median....”.

F. Balfour-Browne (1958: 45), after mentioning the comments of d’Orchymont, states, “My

son has come to the same conclusion, that the main-piece is the basal piece and in this I agree”.

Quaest. Ent., 1980, 16 (1,2)

18

Perkins

It is also possible that the basal piece and median lobe have fused. If so, the major portion of

the main-piece could be homologous to the median lobe, and perhaps the terminal or

pre-terminal process of hydraenid aedeagi is homologous to the internal sac of staphylinoids.

This interpretation has its problems, however. For instance, in Limnebius (Figs. 70,71) the

enlarged base has an internal, coiled duct. In addition, the aedeagus has a well developed,

articulated terminal process. If the terminal process is considered the internal sac homologue,

then what is the homology of the coiled duct? If however the coiled duct is considered the

internal sac homologue, then the terminal process could be considered the median lobe

homologue, and the basal portion becomes homologous to the basal piece.

Returning to Crowson’s (1955) suggestion that the basal piece of hydraenids has become the

ninth sternum, I must disagree with this notion since, as is explained further in the following

section on the abdomen, it appears to me that the last abdominal sternum is actually the tenth,

whereas the ninth sternum has become the rod-like, internal strut (Figs. 2A-E) which is

attached to this last sternum. In many males there is a small swelling near the midregion of this

strut, and a minute fragment of membrane attached at this swelling; these possibly represent

the vestiges of the intersegmental membrane which separated the ancestral ninth and tenth

sterna.

Further, large, short muscles join the end of the strut to the base of the aedeagus (Fig. 2B).

If the strut actually represented the basal piece, these strong muscles would therefore be

between the basal piece and the median lobe, a highly unlikely arrangement.

These strong, short muscles connecting the end of the strut and the base of the aedeagus

present an interesting problem, since they are obviously too short to permit protrusion of the

aedeagus beyond the abdominal apex during copulation. Another group of muscles also attach

at the base of the aedeagus, but these muscles are long and originate on the ninth tergum, and

presumably are those which function to extend the aedeagus. One explanation to resolve this

problem is that the slender strut is flexible and bends to permit extrusion of the aedeagus, then

provides the force, due to its elasticity, to return the aedeagus to its position in the abdomen

when the long muscles relax following copulation.

If one looks closely at the short muscles connecting the strut and the aedeagal base

(Fig. 2B), they are seen to be attached to the aedeagus in two groups, one on each side of the

base. Contraction of these muscles, therefore, would not only cause the aedeagus to be very

slightly drawn closer to the end of the strut, but would also cause extensive rotation of the

aedeagus.

How do these muscles function? I have observed Hydraena marginicollis adults during

copulation, and have seen the following sequence in aedeagal extension: 1) the aedeagus

extends in a straight line posteriorly out of the abdomen, until all, or nearly all, of the aedeagus

(except the curved basal portion) is outside the abdomen; 2) the aedeagus tilts upward so that

its apex is pointed dorsally: 3) the aedeagus swings to the left side of the beetle and continues

this arc until it is directly beneath the midline of the abdomen, in the copulatory position. This

sequence of events is followed in reverse during retraction of the aedeagus, but differs in that

retraction is generally more rapid than extension.

Apparently the muscles and strut function in the following manner: 1) at rest in the

abdomen, the aedeagus is dorsal to the strut, with the curved basal portion (and therefore the

basal opening of the aedeagus) directed dorsally (tilted to the side slightly in some species); 2)

the long muscles connecting the aedeagal base and ninth tergum contract, causing the aedeagus

to emerge from the abdomen on a straight line until the curved base reaches the abdominal

Western Hemisphere Hydraenidae

19

apex, and also causing the strut to bend; 3) further contraction of the long muscles cause the

aedeagus to tilt upward so that it points dorsally; 4) one of the two muscle bundles joining the

aedeagus and strut contracts, causing the aedeagus to swing to the side and then ventrally to

the horizontal, copulatory position; 5) following copulation, contraction of the other of the two

short muscle bundles (and concurrent relaxation of the first) connecting the aedeagal base and

the strut returns the aedeagus to the vertical position; and 6) the long muscles relax, permitting

elasticity of the strut to return the aedeagus to the horizontal resting position within the

abdomen.

In Hydraena marginicollis males the slender tube at the apex of the aedeagus (Fig. 5 5 A) is

inserted into the female and the small, slightly elastic globose portion at the base of the slender

tube comes in contact with the tenth tergum of the female. After insertion of the slender tube,

the male pulsates the aedeagus against the female at a frequency of about two pulsations per

second. It seems likely that this pulsation might cause the bulb at the base of the slender tube to

act as a pump mechanism in sperm transfer. Such a bulb is seen in several species of Hydraena-.

Hydraena pontequula (Fig. 60D); Hydraena guatemala , (Fig. 51 A); Hydraena browni,

(Fig. 53A); Hydraena pulsatrix, (Fig. 55C); etc.

I have observed copulation in a number of Hydraena species, and suspect that

parthenogenesis is quite rare in the family, if it exists at all. F. Balfour-Browne (1958), based

upon the bizarre appearance of some hydraenid aedeagi, concluded that parthenogenesis was

widespread in the family, stating (p. 149), “These Hydraena- group beetles, of which some or

many may still be capable of mating, are in the early stage of a process which has gone much

farther in the sawflies, but my son argues against there being any parthenogenesis among them

and relies upon his work with some of the species in aquaria where he was unable to obtain eggs

until he introduced males. He does not, however, claim to have seen the mating and he does not

attempt to explain how the deformed aedeagus of many of the species can make the contact

with the female”, and regarding the four species of British Limnebius (p. 132), “To suggest

that this type of armature is functional is stretching the imagination too far (reference is to

truncatellus and papposus). Even in nitidus, in which the aedeagophore can still be recognized

as trilobed, the aedeagus has such an elaborate expansion at or near the apex that it also is

probably ornamental and otherwise functionless and I regard all our species as

parthenogenetic”.

Ratios of male/female specimens generally are indicative of bisexual reproduction (see

Appendix A for figures). Two exceptions might be Spanglerina brevis and Hydraena

puncticollis , both of which have very low male/female ratios which might be interpreted as

reflecting facultative parthenogenesis. At one locality in Guatemala, near La Tinta (see

Spangler and Perkins, 1977, figure 20), my wife and I collected 85 specimens of S. brevis , all

female. There were also numerous larvae present, indicating excellent biotic potential for the

site. However, the male/female ratio for a locality in Oaxaca, Mexico (see Spangler and

Perkins, 1977, figure 19) approximated that seen in other species. Hydraena puncticollis , and

what appear to be a few closely related, undescribed species, are only represented in collections

by female specimens. Further field study is needed to determine the causes of low, sporadic

male/female ratios in these species.

Males of some species appear to have developed an internal, sclerotized, protrusible tube

which possibly is the primary intromissive portion of the aedeagus. Gymnochthebius males have

an obvious internal sclerotized tube (Figs. 84A-D,88C) which differs in shape from species to

species. I have seen one specimen which has this tube extended (Fig. 85D) and suspect that

Quaest. Ent., 1980, 16 (1,2)

20

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males of most other species have the ability to extend this tube during copulation (see

discussion section of Gymnochthebius for additional comments). Likewise, Limnebius males

(Figs. 70A,71A,75D) have an internal tube, but it is much different than Gymnochthebius ,

being coiled in the globose base of the aedeagus. As in Gymnochthebius , I have seen only a

single specimen with the tube extended, but suspect it is extended in all species during

copulation.

Males of certain species of Hydraena, such as H. prieto (Fig. 47 A) and H. punctata

(Fig. 44B) have a slender, weakly sclerotized flagellum attached to the terminal portion of the

aedeagus, but it is not known if these structures are retractile. Indeed, the supposition that the

gonopore is located at the apex of these flagella requires verification.

Intraspecific variation in shape of the aedeagus is generally quite slight compared to

interspecific differences . I have illustrated aedeagal morphs where they are significant

{Ochthebius lineatus, Figs. 104,108C,D; Ochthebius discretus, Fig. 134A; Gymnochthebius

fossatus Figs. 91 A-F; etc.). Convergence in shape of the aedeagal “terminal piece” (see below),

which is generally the most species-specific diagnostic portion of the structure, between

distantly related species occurs very infrequently, an example being Ochthebius batesoni and

Neochthebius vandykei (Figs. 143D,146D).

Concerning convergences, one development, loss of parameres, is a commonly derived

condition, appearing in every major phylogenetic lineage within the family (see phylogram,

Fig. 147). Hence, parameres are absent from males of Limnebius (Bilimneus) Hydraena

(Haenydra), and Meropathus. Likewise, J. Balfour-Browne (1976) reported that a species

within the Ochthebius (sensu stricto) lineage (as used herein) also is devoid of parameres.

Partial loss of parameres within certain lineages raises the question of mode of reduction of

these structures. In most species of New World Limnebius the aedeagus has setose

enlargements or patches of setae which probably represent the vestiges of parameres

(Figs. 70A,71A), but these vestiges are located toward the distal end of the “main-piece” (see

below), not near the base, the point of paramere insertion for those aedeagi with well developed

parameres (Fig. 22A).

Likewise, parameres of Hydraena paeminosa males (Fig. 95D) have setose swellings near

the apex of the main-piece, obviously derived from parameres.

Similarly, the aedeagi of Parhydraenida males (Figs. 18A-D) have a very small left

paramere and a spike-like process (which I regard as the remnant of the right paramere - see

discussion section of that genus), both of which are located near the apex of the main-piece, not

attached to the base as in the closely related Hydraenida.

How, then, is paramere loss accomplished, and is the method of reduction the same in the

diverse genera in which this trend is expressed? Two obvious possible modes of reduction come

to mind: 1) loss of the parameres due to reduction in size or the more immediate loss due to

one-step mutation; and 2) gradual fusion of the parameres to the main-piece.

The first explanation appears to apply to Hydraena (Haenydra) species, Ochthebius

lindbergi J. Balfour-Browne (1976; mentioned above), and Meropathus species as males of

these groups have a relatively slender main-piece (no indications of paramere fusion or

remnants of setae) and generally have a small swelling at the base of the aedeagus where

parameres generally originate in other species.

The second explanation, fusion of parameres to the main-piece, might be attributed to those

species of Limnebius whose males have remnants of lobes and patches of setae near the distal

end of the main-piece, the latter being relatively thickened. This mode might also apply to

Western Hemisphere Hydraenidae

21

Parhydraenida, where there is a strong indication of paramere reduction on one side, with the

other paramere showing various degrees of reduction {Parhydraenida paralonga, Fig. 20A;

Parhydraenida reichardti, Fig. 18A; and Parhydraenida lambda , Fig. 18D).

Another explanation might be advanced which relates to the question of the derivation of

the main-piece which was discussed above, i.e., whether this part of the aedeagus is the

homologue of the basal piece or median lobe of other beetles. If one accepts the theory

supported above, as do I, that the main-piece is derived from the basal piece, then it can be

supposed that a lengthening of the ancestral basal piece was necessary to form the heavily

sclerotized, relatively long tube now seen in hydraenids. Therefore, it is possible that in certain

lineages the basal piece elongated distal to the insertion of the parameres, resulting in the

parameres being attached closer to the base of the aedeagus, whereas in other lineages the basal

piece might have elongated proximal to the insertion of the parameres, resulting in parameres

attached near the distal end of the sclerotized tube.

Such evolution of the basal piece might also explain the differences in basic plan of

Gymnochthebius and Ochthebius, as the basal piece in males of the former surrounds the

internal sclerotized tube (presumed homologue of the median lobe) (Fig. 84A), whereas in

Ochthebius males the median lobe (terminal mobile piece) is outside the basal piece and

attached subapically (Fig. 100A).

One cannot deny the great plasticity of the aedeagus in this family, as the illustrations

herein attest. Because of this great variation, I have generally deferred to more descriptive

terminology in reference to the aedeagus, as the hydraenid homologue of the “median lobe” is

generally not median, and the “basal piece” is usually the major portion of the aedeagus

(Fig. 2F). Instead, I have generally used “main-piece” for the basal piece homologue and

“terminal mobile piece” or “terminal piece” for the median lobe homologue (or, as in the case

of Gymnochthebius , the median lobe homologue is termed the “internal tube”).

Abdomen

The abdomen in hydraenids is unusual in a number of respects. First and second terga are

without corresponding sterna (the first tergum is incomplete, represented by two divided,

sclerotized plates). The third tergum, however, does have a sternal counterpart so I assume that

the first complete sternum actually represents the third abdominal segment. Adults of most

genera have a small sclerite between the hind coxae (Fig. 2 ID) which must be derived from the

second abdominal segment (this sclerite is referred to herein as the “intercoxal sternum”).

Counting from the first tergum, therefore, abdominal segments 3-8 are complete and

unambiguous. The sternal counterparts of terga 9 and 10, however, provide a source of

controversy since there is only one obvious sternum which can be associated with the two terga

(Fig. 2A).

As discussed earlier, Crowson (1955) suggested that this small, last sternum was derived

from the ancestral basal piece of the aedeagus. In the previous section on the aedeagus I have

presented my reasons for considering the aedeagus of hydraenids as possessing a basal piece,

therefore, the nature of the last sternum must be explained differently.

This last sternum is unusual in that in males it is prolonged anteriorly into a thin, rod-like

strut (Figs. 2A-E) in the abdomen, joined to the aedeagus by muscles (see previous section).

This strut frequently has a small enlargement near midlength to which attaches a small

fragment of tissue which could be the vestige of the intersegmental membrane separating the

ancestral ninth and tenth sterna. I propose, therefore, that the rod-like strut is the modified

Quaest. Ent., 1980, 16 (1,2)

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Perkins

ancestral ninth sternum and the last sternum present today is the counterpart of the last

tergum, that is, the tenth.

The manner in which the ninth tergum “wraps around” the abdomen (Figs. 2C,3A,B) in

hydraenid males seems to support this hypothesis since its enlargement ventrally would

presumably be associated with an equal reduction in size of the ninth sternum.

In males of hydraenids, the “wrapped around” portions of the ninth tergum are more

developed than in females and in some groups this apparatus is withdrawn into the abdomen,

being concealed by the sixth visible (true eighth) sternum. Consequently, in these groups

inspection of the ventral surface reveals only six sterna. In other groups, especially those such as

the marginicollis Group of Hydraena in which males have the apical (especially ninth tergite)

segments elongate, the “wrapped around” portion of the ninth tergum plus the last sternum are

clearly visible. Hence, in these groups inspection of the ventral surface reveals seven sterna

(Figs. 63A-D).

In females the “wrapped around” portion of the ninth tergum is much less developed and

the last sternum is larger than in males and is exposed. Hence, females always have seven

Western Hemisphere Hydraenidae

23

visible abdominal sterna (Figs. 35C,48B).

In the species descriptions that follow, sterna are referred to in an anatomical sense,

numbering them beginning with the first complete sternum visible (visible #1, true #3) and

ending with the last visible sternum (visible #7, true #10).

Internal Reproductive System

The male reproductive system of hydraenids (Fig. 4A), which has not been previously

described, consists of paired testes, vasa deferentia, lateral accessory glands, median accessory

gland, ejaculatory duct, and aedeagus.

Each testis is a single mass (Figs. 4D,8A) or two separate masses (Figs. 4B,5A,6C).

Differentiation of sperm tubes is (Figs. 7C,8C) or is not apparent.

Ochthebius and Gymnochthebius males differ from one another in that males of

Gymnochthebius (Figs. 4A,B,D,) have a distinct, globose posterior enlargement of the median

accessory gland and the lateral accessory glands are globose also, whereas males of Ochthebius

(Figs. 5,6A,B) lack a posterior enlargement of the median accessory gland and the lateral

accessory glands are generally tubular. In addition, most Ochthebius males have the proximal

end of the vas deferens enlarged which, presumably, serves as a sperm storage area, whereas in

the Gymnochthebius males studied, the vas deferens is not enlarged at the proximal end, but

empties into the globose anterior enlargement of the median accessory gland where sperm

storage probably occurs. The anterior enlargement of the median accessory gland in

Ochthebius assumes remarkable size in some males ( O . tubus , Figs. 6A,B).

Within Ochthebius, I have studied only a single member of the subgenus Asiobates ( O .

discretus , Fig. 5A), which appears to differ from the nominal subgenus in that the proximal

ends of the vas deferens are not enlarged and the median accessory gland is completely tubular,

lacking an anterior enlargement (males of Ochthebius (sensu stricto) studied include O.

lineatus of the interruptus Group, Fig. 5C; O. californicus of the bisinuatus Group, Fig. 5D; O.

gruwelli and O. tubus of the biincisus Group, Figs. 5B,6A,B).

In Hydraena males, the median accessory gland and lateral accessory glands differ

markedly among species groups. The median accessory gland has an anterior enlargement,

but form of the enlargement and manner in which the enlargement and lateral accessory glands

are joined varies. Unlike Ochthebius males, where the anterior enlargement appears simply a

continuation of the median accessory gland, in Hydraena males the anterior enlargement,

although generally small, appears more as an entity distinct from the median accessory gland,

which generally joins its anterior enlargement at the same location as does the common duct of

the lateral accessory glands (Figs. 7A,C).

In males of Hydraena anisonycha (Fig. 8D), the major glandular region of the median

accessory gland is situated more toward the proximal end, whereas the anterior enlargement is

relatively small. Males of this species are unique among those studied in possession of distinct

lacunae formed by a tight loop of the vas deferens.

Hydraena d-destina males (Fig. 8C), by contrast, have the anterior enlargement of the

median accessory gland very large and quite complex, with the lateral accessory glands

adpressed to its surface, the entire complex mass being topped by a twisted portion of the

median accessory gland. Males of this species are also unusual in form of the sperm tubes,

which are frequently coiled into flat discs.

In Hydraena bituberculata males, (Fig. 8A) the anterior enlargement of the median

accessory gland is well developed, as are the lateral accessory glands.

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Figs. 4A - D, Internal reproductive structures. (A) Gymnochthebius nitidus, 3 (testes omitted). (B) G.fossatus, 3. (C)

nitidus, 9. (D) G. clandestinus, 3 (plus abdominal ganglion). (B-D at same scale).

Western Hemisphere Hydraenidae

25

Figs. 5A - D, Male internal reproductive structures. (A) Ochthebius discretus. (B) O. gruwelli. (C) O. lineatus. (D) O.

californicus. (testes omitted from B, C and D).

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Figs. 6A - C, Male internal reproductive structures. (A) Ochthebius tubus , specimen from Monterey County, California.

(B) O. tubus, specimen from San Luis Potosi, Mexico. (C) Limnebius sinuatus.

Western Hemisphere Hydraenidae

27

Figs. 7 A - E, Internal reproductive structures. (A) Hydraena atlantica, 6. (B) H. circulata $ (C) H. marginicollis , <3.

(D) H. spangleri <3. (E) H. spangleri, 2. (testes omitted from A, B and D).

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Figs. 8 A - D, Internal reproductive structures. (A) Hydraena bituberculata , <?. (B) H. atlantica, 9. (C) H. d-destina, 6.

(D) H. anisonycha, <3 (part of testis illustrated).

Western Hemisphere Hydraenidae

29

In males of Hydraena atlantica and Hydraena circulata (Figs. 7A,B) the anterior

enlargement of the median accessory gland is weakly to moderately developed, the lateral

accessory glands being well developed and united to the anterior enlargement by a common

duct.

The reproductive system of Limnebius sinuatus (Sharp) males (Fig. 6C) is relatively simple,

but differs from the others mentioned in that the vas deferens are quite short and the median

accessory gland is rather elongate, having a distinct, slightly expanded portion between the

highly glandular anterior enlargement and the vas deferens. The lateral accessory glands are

well developed.

Preliminary study suggests that at least some differences are detectable in the male

reproductive system of closely related species. These differences relate to shape of the anterior

enlargement and manner in which the vas deferens and lateral accessory glands join this

enlargement. Thus, in Hydraena circulata and Hydraena atlantica males, differences in this

region illustrated (Figs. 7A,B) are constant in the few specimens of each species studied.

Differences in shape of the lateral accessory glands illustrated, however, are not constant, as

males of Hydraena atlantica with curled apical portions of the lateral accessory glands have

been seen. Differences are also evident between the two males of Ochthebius tubus illustrated

(Figs. 6A,B). These may, in fact, represent two species, as the form from Mexico (Fig. 6B)

differs also in aedeagal structure (see Fig. 124C) from the California form (Figs. 6A,124D).

Further study is needed to determine reliability of internal reproductive structures as indicators

of specific distinction.

The female reproductive system (Figs. 4C,8B,9,10) consists of ovaries (4-6 egg tubes),

bursa copulatrix, spermatheca, spermathecal accessory gland and spermathecal duct. Also

illustrated (Fig. 8B) are the presumed silk producing glands.

Females of New World hydraenids have a sclerotized spermatheca provided with an

accessory gland and connected to the bursa copulatrix by a spermathecal duct. The

spermathecal duct is very short, in Gymnochthebius females, or quite elongate, in Limnebius

females. Generally, the spermatheca has a lightly sclerotized, flexible central region and

muscles connecting the more heavily sclerotized proximal and distal portions (Figs. 9I,10B,H).

Contraction of these muscles presumably causes the central region to flex, thereby acting as a

pump mechanism.

Spermathecae vary considerably in shape between females of most genera, and between

some species groups (cf. G. oppositus and G. germaini. Figs. 9E,I). Females of a few closely

related species differ in spermathecae form, (cf. G. laevipennis G. perlabidus and G.

maureenae. Figs. 93H-J). Such differences between sister-species, however, are exceptional.

Representative spermathecae are illustrated (Figs. 9A-I,10K). The highly convoluted

spermatheca of Meropathus vectis (Fig. 146C) is the most unusual.

Stridulatory Structures

Adults of a number of species in the leechi Group of New World Hydraena (all of the leechi

and alternata Subgroups plus certain species in the scintillabella Subgroup) have a flat,

smooth, generally oval and totally impunctate surface at the midpoint of the anterior pronotal

margin (Figs. 31C,E,G,32B,40D). Viewed with the intense light of the microscope, this

previously unreported structure appears as a small, brassy reflection; hence it is termed a

“scintilla” (Latin for spark). I am grateful to Hugh B. Leech for bringing this structure to my

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Perkins

Figs. 9A - I, Spermathecae of Gymnochthebius species. (A) G. clandestinus. (B) G. topali. (C) G. bartyrae. (D) G.

compact us. (E) G. germaini. (F) G. curvus. (G) G. chilenus. (H) G. tectus. (I) G. oppositus.

Western Hemisphere Hydraenidae

31

Figs. 10A - K, Spermathecae. (A) Ochthebius tubus. (B) O. californicus. (C) O. lineatus. (D) O. crenatus. (E) O.

benefossus (F) O. obscurus. (G) Parhydraenida reichardti. (FI) Spanglerina brevis. (I) Hydraena circulata. (J) H.

arizonica. (K) Limnebius sinuatus.

Quaest. Ent., 1980, 16 (1,2)

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attention at the outset of this study.

Viewed with the scanning electron microscope, the scintilla is seen to be an extremely thin

shelf above a specialized area on the occipital region of the head (Figs. 31 A,D,32A,C,40A,C).

This region is transverse ridged in males, but these ridges are absent from females. There is

little doubt that these interesting structures function together as a stridulatory device.

Figs. 1 1 A - D. (A) Metacoxal sensillum, Ochthebius tubus. (B) Metacoxal sensillum, Limnebius sinuatus. (C) Metacoxal

sensillum, Parhydraenida reichardti. (D) Surface of eye, P. reichardti.

Presence of debris on each side of the occipital ridges in the specimen of Hydraena arizonica

illustrated (Figs. 32A,C) nicely confirms the supposition that the scintilla is rubbed against

these ridges; absence of debris clearly indicates the area of contact. Absence of ridges from

females suggests that perhaps stridulation functions as a recognition signal between opposite

sexes of a species, rather than merely a warning signal. Apparently females, which have a

smaller scintilla than their respective male counterparts, have either lost the ridges, or the

influence of the genes which cause expression of the scintilla in males is so pervasive that the

scintilla is also formed in females although it is without function (a similar phenomenon with

respect to sexual dimorphism appears in species of Hydraena , such as Hydraena d-destina , in

which the male metatibiae are greatly expanded and the females slightly so).

Western Hemisphere Hydraenidae

33

Interspecific variation in number, spacing and shape of ridges has been seen on the few

species which have been studied with the scanning electron microscope, and I suspect these

differences to result in a different pitch for each species.

Adults of seven species of the leechi Subgroup, the single species of the alternata Subgroup,

plus most of the 17 species in the scintillabella Subgroup, have the scintilla well developed.

Adults of a few species in the scintillabella Subgroup, such as Hydraena exilipes and

Hydraena ozarkensis , have the scintilla very narrow (Fig. 40D). It reaches minimum

expression in Hydraena colombiana adults.

Pronotal sensilla

Adults of Limnebius have four moderately distinctive, short setae near the anterior margin

of the pronotum, and six similarly sized and spaced setae near the posterior margin (Fig. 69 A).

Brown (1932), in his description of L. columbianus, was the first author to mention these setae.

Later, d’Orchymont (1945b) noted that these setae were present in all of the Limnebius

material he had studied, and suggested that perhaps they were of generic significance.

Examination by scanning electron microscopy has revealed these setae on the pronota of

adults of certain species of Hydraena , Parhydraenida , Gymnochthebius, and Ochthebius

(Figs. 15E,F,48C,82C,106C,128A). I have not searched for these setae in all species, but this

preliminary survey indicates that these structures are generally found in adults with relatively

smooth surfaces, but are frequently absent from or obscured in adults with coarsely sculptured

surfaces.

The constant morphological location of these setae and their presence in species from all of

the major phylogenetic lineages indicates that their presence is a plesiotypic character state,

and also suggests that they serve some sensory function. Discovery of these pronotal sensilla in

a sublineage of either the Hydrophiloidea or Staphylinoidea would aid in determining the

phylogenetic relationships of the family Hydraenidae.

Metacoxal sensilla

Adults of Parhydraenida , Hydraena , Spanglerina, Limnebius, Gymnochthebius and

Ochthebius possess a curious, disc-shaped structure on the hind coxa

(Figs. 1 1A-C,16C,21D,57B,65C). This “pad”, a previously unreported morphological feature

of the family, appears to be situated on the hind coxae so that flexure of the metatibia causes

contact between the anterior surface of the metatibia (and/or the trochanter) and the “pad”.

Function of this pad is a matter of conjecture; I can only suggest that perhaps it serves as a

pressure sensor. Water flowing over the beetle (from anterior toward posterior as the insect

faces into the current) would force the body backward slightly, causing the anterior surface of

the metatibia to contact the metacoxal pad sensilla. Pressure on these sensilla might possibly,

therefore, be directly proportional to flow rate and serve to monitor the beetle’s position.

Lateral water flow might cause pressure on only one sensillum, and therefore not only detect

flow rate, but also direction relative to the beetle.

I have not found these sensilla in Meropathus adults (using light microscopy), which may

indicate secondary loss associated with terrestrial habits.

These metacoxal pad sensilla are probably a primitive character for the family, as they are

found in diverse lineages. Discovery of these structures in a sublineage of the Hydrophiloidea or

Staphylinoidea would aid in phylogenetic placement of the family Hydraenidae.

Quaest. Ent., 1980, 16 (1,2)

34 Perkins

KEY TO GENERA OF WESTERN HEMISPHERE HYDRAENIDAE

1 Antenna with eleven articles (Figs. 16B,148B); maxillary palpomeres 2 and 4

subequal in length, 3 about one-half length of 4 (Figs. 16A,148B); venter of

head grooved for reception of antennae (Fig. 16A); South America 2

T Antennae with nine articles (Figs. 69H,148A,C,D); maxillary palpus various,

not as above (Figs. 21 A,69B,128C,148A,C,D); venter of head not grooved for

reception of antennae (Figs. 21 H,128C); North and South America 3

2 (1 ) Pronotum subcordate, sides sinuate near posterior angles (Figs. 15A,17A-H);

elytra with serial rows of punctures in sulcate impressions, intervals costate or

subcostate (Fig. 16F); aedeagus with left paramere inserted near apex, right

paramere absent or reduced to small spike near apex (Figs. 18A-D)

Parhydraenida J. Balfour-Browne, p. 45

2' Pronotum with sides straight near posterior angles (Figs. 12A,C); elytra with

serial rows of punctures not in sulcate impressions, intervals flat or slightly

rounded; aedeagus with both parameres elongate, inserted near base

(Figs. 13 A, B) Hydraenida Germain, p. 40

3 (T) Maxillary palpomere 3 longer and broader than 4 (Figs. 98B,103C,148A);

pronotum with transparent or semi-transparent borders at anterior and posterior

margins, with or without transparent lateral margins also (Figs. 96A-F) .... 4

3' Maxillary palpomeres 3 and 4 subequal in length (Figs. 69B,148D), or with 3

much shorter than 4 (Figs. 48A,148C); pronotum without transparent borders

7

4 (3 ) Elytra interlocked, wings absent; eyes reduced, facets very convex

(Figs. 145A-C,146A,B); pronotum without lateral transparent borders;

intertidal or coastal species 5

4' Elytra not interlocked, wings present; eyes not reduced, facets less convex

(Fig. 103B); pronotum with lateral transparent borders more or less developed

(Figs. 96A-F); primarily fresh or brackish water species 6

5 (4 ) Size large (ca. 2.30 mm long) with well developed dorsal pubescence

(Fig. 146A); aedeagus without parameres; one species from Isla de los Estados

and Falkland Islands Meropathus Enderlein, p. 406

5' Size small (ca. 1.65 mm long) without well developed dorsal pubescence

(Figs. 145A-C); aedeagus with parameres (Fig. 146D); one intertidal species,

found on the Pacific coast from British Columbia to California

Neochthebius d’Orchymont, p. 408

6 (4') Aedeagus with apex of main-piece bifid; single process between lobes, extended

or not beyond main-piece. Parameres longer than main-piece

(Figs. 81 A,B,84A-D). Pronotum of many specimens with sides of sclerotized

part deeply emarginate in both anterior and posterior 0.50; between these

emarginations sides produced in sharp point (Figs. 80A,96B); anterior margin

of pronotum deeply emarginate in front of lateral fossulae; anterior angles

lobate, markedly so in some specimens less so in others (North, Central and

South America). In other South American specimens anterolateral

emargination less developed (Fig. 80C), anterior angles less lobate; in still

Western Hemisphere Hydraenidae

35

others (Fig. 80E) anterolateral emargination very shallow, pronotum similar to

that of some adults of Ochthebius ( sensu stricto). In few adults, angulation

between antero- and posterolateral emarginations very large, exceeding in size

lobe formed by anterior angles of pronotum (Figs. 89D,E); North and Central

America Gymnochthebius d’Orchymont, p. 244

6' Aedeagus with main-piece not bifid at apex; single, preterminal, articulated

process extended beyond apex of main-piece. Parameres shorter than main-piece

(Figs. 100A-D). Pronotum with sclerotized part of diverse forms

(Figs. 96A,C-F), but not with markedly lobate anterior angles as described

above. Pronotum of some specimens very transverse, sides gradually rounded

from anterior angles to behind the middle, then deeply notched (Subgenus

Asiobates , Figs. 133A-F). Pronotum of many specimens with sides sinuate and

convergent to base ( Ochthebius ( sensu stricto), Figs. 1 19A-H)

Ochthebius Leach, p. 292

7 (30 Maxillary palpus with second segment very elongate, much longer than third

(Fig. 148C) 8

T Maxillary palpus with second and third segments subequal in length

(Fig. 148D); sides of body evenly arcuate (Fig. 69A) . . . Limnebius Loach, p. 222

8 (7 ) Pronotum markedly angulate in middle, with median ridge and anterointernal

foveolae (Fig. 65E); labium with depressions near anterior margin (Fig. 65F);

procoxae as widely separated as mesocoxae (Fig. 65D); metacoxae widely

separated (Fig. 65C) Spanglerina , new genus, p. 212

8' Pronotum very weakly to moderately angulate in middle, without a median

ridge and anterointernal foveolae (Figs. 21C,48C,54C); labium without

depressions near anterior margin (Figs. 21H,48E,54D); procoxae closer together

than mesocoxae (Figs. 21D,E,48H,54B); metacoxae usually not widely

separated (Figs. 21D,48D,54B) Hydraena Kugelann, p. 60

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CHECKLIST OF WESTERN HEMISPHERE HYDRAENIDAE

Western Hemisphere Hydraenidae

37

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The geminya Subgroup

92. H. vela , new species p. 206

93. H. chiapa, new species p. 207

94. H. geminya ,

new species p. 209

The paeminosa Group

95. H. paeminosa ,

new species p. 211

Genus Spanglerina, new genus

The ingens Group

1. S', ingens, new species p. 216

2. S. fluvicola,

new species p. 218

The brevis Group

3. S. brevis (Sharp) p. 220

4. S. frondsicola,

new species p. 220

Genus Limnebius Leach

1 . L. discolor Casey p. 227

2. L. richmondi,

new species p. 227

3. L. ozapalachicus,

new species p. 230

4. L. piceus (Horn) p. 230

5. L. alutaceus (Casey) p. 230

6. L. arenicolus,

new species p. 234

7. L. leechi, new species p. 235

8. L. borealis

, new species p. 235

9. L. utahensis,

new species p. 236

10. L. sinuatus (Sharp) p. 236

11. L. angustulus (Casey) p.238

12. L. mitus, new species p. 238

13. L. texanus, new species . p. 241

14. L. aridus, new species p. 241

15. L. mexicanus,

new species p. 243

16. L. octolaevis,

new species p. 243

Genus Gymnochthebius d’Orchymont

The plesiotypus Group

1 . G. plesiotypus,

new species p. 251

2. G. jensenhaarupi

(Knisch) p. 253

3. G. octonarius,

new species p. 254

The germaini Group

The germaini Subgroup

4. G. germaini (Zaitzev) p. 256

5. G. chilenus

(J. Balfour-Browne) p. 257

6. G. clandestinus,

new species p. 258

7. G. tectus, new species p. 261

8. G. curvus, new species p. 262

9. G. bisagittatus,

new species p. 264

10. G. francki (Bruch) p.264

11. G. topali

(J. Balfour-Browne) p. 265

12. G. compactus,

new species p. 267

13. G. peruvianus

(J. Balfour-Browne) p. 268

14. G. bartyrae,

new species p. 270

The reticulatus Subgroup

15. G. reticulatus

(d’Orchymont) p. 271

16. G. reticulatissimus,

new species p. 273

The nitidus Group

The nitidus Subgroup

17. G. nitidus (LeConte) p. 274

18. G. fossatus (LeConte) p. 277

1 9. G. falli, new species p. 28 1

The laevipennis Subgroup

20. G. laevipennis

(LeConte) p. 283

21. G. crassipes (Sharp) p.284

22. G. perlabidus,

new species p. 286

23. G. maureenae,

new species p. 287

The oppositus Subgroup

24. G. oppositus.

new species p. 289

25. G. seminole,

new species p. 290

Genus Ochthebius Leach

Subgenus Ochthebius (sensu stricto)

The interrupt us Group

The interruptus Subgroup

1 . O. pacificus,

new species p. 306

2. O. arenicolus.

Western Hemisphere Hydraenidae

39

Quaest. Ent., 1980, 16 (1,2)

40

Perkins

GENUS HYDRAENIDA GERMAIN

Hydraenida Germain, 1901: 531 (type species: Hydraenida ocellata Germain, 1901: 536). - d’Orchymont, 1929: 96. -

J. Balfour-Browne, 1975: 44.

Discussion. - As d’Orchymont (1929) pointed out, the eleven segmented antenna is the

unusual structure of adults of this genus, not the ocelli as Germain(1901) had thought. Also of

significance, but not mentioned by d’Orchymont or J. Balfour-Browne (1975) is form of the

ventral surface of the head, which is grooved laterally for reception of the antennae.

Hydraenida adults share this feature with the adults of Parhydraenida (Fig. 16A) and of the

African genus Coelometopon. A discussion of relationships of Hydraenida are developed more

fully in the section on phylogeny.

Specimens of this genus are still exceedingly rare in collections, although 77 years have

elapsed since its description. In fact, only eight specimens other than those which Germain

studied have been seen by subsequent specialists.

Figs. 12A - C, Body outlines. (A) Hydraenida robusta. (B) Parhydraenida alida. (C) Hydraenida ocellata.

The scant information available about habitat preferences of Hydraenida members consists

of that given by Germain (1901), “de los arroyuelos que bajan por las quebradas de Quillota,

Aculeo, Lo Aquila, etc.”, plus H.P. Brown’s label citation, “tributary to Rio Maule”, the latter

referring to the specimens of H. robusta. These notes suggest that adults of this genus are not

Western Hemisphere Hydraenidae

41

hygropetric as are adults of closely the related Parhydraenida. However, P. Spangler collected

six specimens of H. robusta from a “roadside seep”, a label citation which frequently identifies

madicoles. Further field work is necessary to clearly establish habitat preferences of

Hydraenida species.

Pronotal features. - Pronota of Hydraenida adults (Fig. 12A,C) are similar to those of

Parhydraenida adults (Fig. 15 A) in possession of lateral depressions and lateral fossulae.

Hydraenida adults differ in that the anterior foveae and posterior foveae are not united to form

U-shaped depressions as they are in Parhydraenida adults. Also, the pronotum of

Parhydraenida adults is cordiform whereas that of Hydraenida adults is not.

Diagnosis. - Adults of this genus shares with those of Parhydraenida : 1 ) antennomeres 1 1 ,

(Fig. 16B); 2) grooves on venter of head into which the antennae are inserted, (Fig. 16A); 3)

form of the maxillary palpus (Fig. 16A); 4) form of the metasternum, and most other

characteristics. Differences are in the elytral sculpture, which has the primary serial rows of

punctures very weakly striate-impressed, if at all, and the intervals very slightly rounded. In

Parhydraenida adults the primary rows are sulcate-impressed (Fig. 16F) and the intervals

subcostate or costate. Additionally, pronota of Hydraenida adults have the sides straight at the

rear (Fig 12A,C) whereas the sides are sinuate in Parhydraenida (Fig. 15A,17A-H), forming a

subcordate shape. The aedeagi of Hydraenida males have the parameres attached at the base

and elongate (Fig. 13A,B), whereas those of Parhydraenida males are usually very short and

attached near the apex, the right reduced to a spike or absent (Fig. 18A-D) (refer to the

discussion section of Parhydraenida for further comments).

Description. — Form: Elongate-oval, moderately convex (Fig. 12B, 17A-H) Size: Length 2.00-2.20 mm, width

0.85-0.95 mm. Most females slightly larger than males. Color Dark brown. Head: Moderately punctate, markedly

microreticulate dorsally. Interocular foveae shallow. Interocular tuberculi (ocelli) present. Clypeus transverse, sides

convergent. Labrum with anterior margin weakly upturned in males, shallowly emarginate in females. Maxillary palpus

moderately long, last three segments with approximate ratio of 2:1:2. Mentum trapezoidal, width at base equal length;

microreticulate; anterior margin straight. Genae swollen in midregion, grooved laterally for reception of antennae.

Antennae 1 1 segmented (6 + 5). Thorax: Pronotal sides straight at rear. Anterior margin markedly bisinuate, middle 0.20

straight or nearly so, anterior angles produced. Lateral depression with moderately impressed longitudinal fossula, strongly

microreticulate. Disc with two pairs of moderately impressed foveae, anterior pair joined to one another by shallow

depression. Posterior margin of pronotum slightly arcuate to rear in midregion. Prosternum slightly elevated transversely,

coxae contiguous. Metasternum entirely hydrofuge pubescent, longitudinally depressed in midline. Elytra: Disc with six

rows of small punctures, each puncture with a seta; rows very slightly striate-impressed near suture, not striate elsewhere.

Intervals rounded slightly or flat, nearly three times width of primary serial punctures; each interval with row of punctures

nearly equal in size to those of primary rows; each puncture with seta subequal to those of primary rows. Declivity

beginning near posterior 0.33. Explanate margin weakly developed. Abdomen: Basal four sterna and anterior 0.25 of fifth

sternum hydrofuge pubescent, remainder shiny, finely sparsely pubescent. Legs: Of moderate length and build. Genitalia:

Aedeagus with parameres attached near base.

1 . Hydraenida ocellata Germain

(Figs. 12C,13B,14A)

Hydraenida ocellata Germain, 1901: 531 (lectotype male deposited in MHNC; type-locality: Quillota, Chile). -

d’Orchymont, 1929:96. -J. Balfour-Browne, 1975:44.

A lectotype for this species has been designated by J. Balfour-Browne (1975).

Diagnosis. - Adults of this species are slightly smaller and have the dorsal microreticulation

slightly more developed than have adults of the very similar H. robusta. The only totally

reliable means of differentiating these two species is by referral to the remarkably dissimilar

aedeagal forms (Figs. 13A,B)of males.

Description. — Form: Elongate, oval, moderately convex (Fig. 12C). Size: Approximately 2.00 mm long, 0.85 mm

wide. Color Dark brown. Head: Length 0.38 mm; width 0.56 mm. Frons markedly microreticulate, punctures obsolete.

Quaest. Ent., 1980, 16 (1,2)

42

Perkins

Figs. 13A - B, Aedeagi of Hydraenida species. (A) H. robusta , holotype. (B) H. ocellata.

interocular foveae shallow, width of each nearly 0.66 distance separating them; interocular tuberculi large; basomedial

fovea absent. Frontoclypeal suture bisinuate. Clypeus length slightly less than 0.50 width; markedly microreticulate.

Labroclypeal suture straight. Labrum length 0.50 width, strongly microreticulate; anterior margin weakly emarginate,

but weakly upturned margin gives the appearance of a nearly straight anterior edge in habitus view. Maxillary

palpomere 4 (apical) slightly longer than 2 (pseudobasal); palpomere 3 about 0.50 length of 4. Mentum trapezoidal,

width at base equal length; microreticulate finely punctate,; anterior margin straight. Submentum punctulate. Genae

swollen, dull, punctulate, grooved laterally. Postgena finely punctulate. Thorax: Pronotum length at midline 0.46 mm;

maximum width (near anterior 0.33) 0.76 mm. Anterior margin bisinuate, anterior angles produced. Lateral depressions

markedly microreticulate, punctures nearly obscured by microreticulation; sides not apparently crenulate, straight from

near anterior 0.33 to posterior angles. Lateral fossulae very shallow, with same sculpture as lateral depressions. Pronotal

disc markedly microreticulate, densely punctate, dull except for small shiny area in midline slightly behind middle; with

anterior and posterior pair of moderately impressed foveae, anterior pair joined to one another by shallow depression.

Posterior margin weakly arcuate to rear in midregion. Prosternum slightly elevated along anterior margin; coxae

contiguous. Metasternum longitudinally impressed at midline, entirely hydrofuge pubescent. Elytra: Length 1.36 mm;

maximum width (near midlength) 0.85 mm. Disc shiny, much more reflective than pronotum. shallowly depressed in

midregion, with six rows of small punctures between suture and humeri, rows extremely slightly striate impressed on

disc; each puncture with short seta. Intervals flat or very slightly rounded, nearly three times width of punctures in

shallow striae; each interval with row of punctures nearly equal in size to those of primary rows; each puncture with

seta subequal to those of primary rows. Declivity beginning near posterior 0.33. Explanate margin slightly developed.

Abdomen: Basal four sterna and anterior 0.25 of fifth sternum hydrofuge pubescent, remainder shiny, finely sparsely

pubescent. Legs: Of moderate length and build. Genitalia: Male (Fig. 13B) (1 examined).

Natural History. - Germain (1901) states: “Este insecto es anchamente oblongo i

deprimido; i se halla, por los meses de verano, pegado en la parte inferior de las piedras medio

Western Hemisphere Hydraenidae

43

sumerjidas de los arroyuelos que bajan por las quebradas de Quillota, Aculeo, Lo Aguila, etc.”.

Distribution. - (Fig. 14A). Central Chile, in Valpariso Province (Quillota) and, according

to J. Balfour-Browne (1975) Santiago Province (Aculeo and Hospital).

Remarks. - It is remarkable that neither d’Orchymont (1929) nor J. Balfour-Browne

(1975) nor myself have seen specimens other than those which were before Germain at the time

of the original description (1901).

2. Hydraenida robust a new species

(Figs. 12A,13A,14A)

Type-locality. - Tributary to Rio Maule, Maule Province, Chile.

Type-specimens. - The holotype male is deposited in USNM. This specimen was collected

by Harley P. Brown on November 2, 1971. The allotype, collected by H.P. Brown on November

1, 1971, is from Colchagua Province, e. Aguas Buenas, and is also deposited in USNM. One

male and one female paratype from Valpariso Province, Quillota (originally part of Germain’s

type series of H. ocellata ), are deposited in MHNC. Six paratypes (three of each sex) deposited

in USNM have the following data: Chile, Bio-Bio Prov., Santa Barbara (1 km S.) roadside

seep, 25-Jan.-1978, P.J. Spangler.

Diagnosis. - Males of this species are distinguished from those of H. ocellata by

differences in the aedeagus. Females of the two species cannot be distinguished from one

another by structural characteristics.

Description. — Form: Elongate oval, moderately convex (Fig. 12A). Size: Holotype 2.20 mm long, 0.92 mm wide.

Color Head and pronotum dark brown, remainder brown. Head: Length 0.40 mm; width 0.62 mm. Frons markedly

microreticulate, punctures nearly obscured; interocular foveae shallow, width of each nearly 0.66 distance separating

them; interocular tuberculi large; basomedial fovea shallow, transverse. Frontoclypeal suture bisinuate. Clypeus length

slightly less than 0.50 width; small anteromedial area shiny, remainder dull, markedly microreticulate. Labroclypeal

suture straight. Labrum length 0.50 width; markedly microreticulate, moderately densely pubescent; anterior edge

straight, upturned. Maxillary palpomere 4 (apical) slightly longer than 2 (pseudobasal); palpomere 3 0.50 length of 4.

Mentum trapezoidal, concave, width at base equal length; microreticulate, finely punctate; anterior margin straight.

Submentum concave, markedly microreticulate. Genae swollen, dull, punctulate, grooved laterally for reception of

antennae. Postgena punctulate. Thorax: Pronotum length at midline 0.50 mm; maximum width (near anterior 0.33)

0.82 mm. Anterior margin bisinuate, anterior angles produced. Lateral depressions markedly microreticulate, moderately

punctate; sides apparently. not crenulate, or extremely finely so, straight from near midlength to posterior angles. Lateral

fossulae with sculpture as lateral depressions. Pronotal disc markedly microreticulate, densely punctate, dull except for

shiny relief in middle; with an anterior and a posterior pair of well impressed foveae, the anterior pair joined one to the

other by a shallow depression to form a V-shaped figure. Posterior margin arcuate to rear in midregion. Prosternum very

slightly elevated in midline; coxae contiguous, metasternum longitudinally depressed in midline, entirely hydrofuge

pubescent. Elytra: Length 1.48 mm; maximum width (near midlength) 0.92 mm. Disc shiny, much more reflective than

pronotum, shallowly depressed in midregion, with six rows of small punctures between suture and humeri, rows extremely

slightly striate impressed; each with a distinctive short seta. Intervals flat or very slightly rounded, nearly three times width

of punctures in shallow striae; each interval with a row of punctures about 0.50 the size of punctures in primary rows; each

puncture with a seta subequal in size to those of primary rows. Declivity beginning near posterior 0.33. Explanate margin

weakly developed. Abdomen: Basal four sterna and anterior 0.25 of fifth hydrofuge pubescent, remainder shiny, finely

sparsely pubescent. Legs: All legs of moderate length and build. Protarsi with large pad of suction setae on basal three

segments. Mesotarsi also apparently with suction setae on basal three segments, although not forming pads. All claws with

a small tooth on lower surface near base, those of protarsi slightly larger than others. Genitalia: Male (Fig. 13A) (two

examined).

Variation. - Females lack pro- and mesotarsal suction setae and do not have the anterior

margin of the labrum upturned.

Distribution. - (Fig. 14A) Central Chile, in the provinces of Valpariso, Colchagua, Bio-Bio,

and Maule.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Figs. 14A - B, Geographical distributions. (A) Hydraenida robusta • and H. ocellata ★.(B) Parhydraenida reichardti

• and P. effeminata ★ .

Western Hemisphere Hydraenidae

45

Etymology. - Latin, robusta (strongly built). I refer to the very stout aedeagus.

Remarks. - J. Balfour-Browne (1975) illustrated the aedeagus of a species of Hydraenida

which he preferred not to describe because the adult body had been fragmented due to

“treatment with caustic potash”. The illustration he provides agrees well with that of H.

robusta except for the shape of the apical piece; it seems likely that the caustic potash

mentioned above deformed the aedeagus of his specimen.

GENUS PARHYDRAENIDA J. BALFOUR-BROWNE

Parhydraenida J. Balfour-Browne, 1975:39 (type species: Parhydraenida reichardti, 1975: 40).

Discussion. - This interesting genus was recently described by J. Balfour-Browne (1975) for

four species of hydraenids found in the mountains of southeastern Brazil. In justifying

establishment of this genus, Balfour-Browne states, “By the 11 -segmented antennae, distinct

ocelli and most other characters this group might well be attached to Hydraenida Germain but

the almost cordate pronotum and the absence of aedeagal parameres demand that they be

separated therefrom.”

Close inspection of the aedeagus, however, reveals that it invariably has a left paramere, and

most have a spike-like process which I regard as a remnant of the right paramere. This is true

for the three species Balfour-Browne described (one species is known only by females) and for

the four new species described herein.

The left paramere has apical setae, typical for this structure, in all species except one, P.

lambda. In this species the left paramere is greatly reduced in size (Fig. 18D) and somewhat

spike-like. It is the shape of the left paramere in P. lambda males that suggests that the other

spike-like process, near the apex of the aedeagus, is the vestigial right paramere. This proposed

vestigial, spike-like paramere characterizes males of the following four species: P. reichardti , P.

lambda , P. quadraticeps, and P. hygropetrica. The aedeagus of P. bubrunipes males has a

setose swelling near the apex which is probably derived, at least in part, from the right

paramere (Fig. 19).

P. paralonga males have a relatively long left paramere, about 0.33 the total length of the

aedeagus (Fig. 20A). In males of other species this paramere is much smaller relative to

aedeagal length.

In contrast to the parameres of Hydraenida , however, those of Parhydraenida are inserted

near the apex of the aedeagus and are very short; those of Hydraenida are long and inserted

near the base (Figs. 13A,B). Additionally, the aedeagus of Hydraenida males is straight,

whereas that of Parhydraenida males appears to be twisted. This twisting is reflected in the

shape of the aedeagal base where the ejaculatory duct enters, which is displaced to the left.

The subcordate pronotum emphasized by Balfour-Browne has been found to be consistently

present in the adults of the new species described herein. Additionally, all of the known adults

have the elytral series sulcate impressed, which presents a much different appearance from the

elytra characteristic of the two species currently known for Hydraenida. Based upon the

aedeagal differences, mentioned above, plus the pronotal and elytral differences, I am

considering this group worthy of generic status.

However, area and habitats which remain to be sampled in South America are so very

extensive, and the morphological gap separating these two genera is so narrow, that the

probability of intermediates being discovered would appear to be less than remote.

Quaest. Ent., 1980, 16 (1,2)

46

Perkins

Figs. 15A - F, Parhydraenida reichardti, 6. (A) head and pronotum (AUD = anterior U-shaped depression, LD =

lateral depression, LF = lateral fossula, PUD = posterior U-shaped depression). (G) anterior aspect of head. (C,D)

labral emargination. (E) ocelli and anteromedian region of pronotum (arrows indicate pronotal sensilla). (F)

posteromedian region of pronotum.

Western Hemisphere Hydraenidae

47

Figs. I6A - F, Parhydraenida reichardti, 6. (A) head, lateral aspect, (arrow indicates antennal groove). (B) antenna. (C)

metasternum. (D) mesosternum. (E) abdomen. (F) elytra.

Quaest. Ent., 1980, 16 (1,2)

48

Perkins

Judging from the unusual hydrofuge pubescence of P. pentatenkta adults from Ecuador,

which is geographically quite removed from the remaining eight species of southeastern Brazil,

even the discovery of the male of that species will add considerably to our knowledge of the

genus.

I have seen two females of a species from Paraguay, which suggests that further collecting

may eventually provide geographical intermediates between the southeastern Brazilian and

Ecuadorian components of Parhydraenida. These two females probably represent an

undescribed species. However, they are not sufficiently distinct to warrant formal description

without the diagnostic features of the aedeagi that males would provide. Based upon ventral

pubescence, these two females are members of the reichardti Group.

Pronotal Features. - The major relief features of Parhydraenida pronota (Fig. 15 A) consist

of an anterior (AUD) and posterior (PUD) U-shaped depression, rather broad lateral

depressions (LD), and lateral fossulae (LF). In adults of most species the posterior U-shaped

depression does not join the lateral fossulae, and the lateral fossulae are not divided into distinct

anterior and posterior foveae (Figs. 17F-H). P. reichardti adults (Figs. 15A,17C), however, are

an exception in both respects. Infrequently, as in adults of P. effeminata (Fig. 17E), the

pronotal sculpture is very obsolete, with only a suggestion of the depressions seen in the other

species.

Diagnosis. - Combination of eleven segmented antennae (Fig. 16B) and form of the

maxillary palpus, which has the apical (fourth) segment about twice as long as the third and

subequal that of the second (pseudobasal) (Fig. 148B), readily distinguish Parhydraenida

adults from all those of New World genera of Hydraenidae except Hydraenida. Adults of these

two genera are also unique in form of the ventral surface of the head, which is grooved laterally

for reception of the antennae (Fig. 16A). The subcordate pronotum of Parhydraenida adults

(Figs. 15A,17A-H), plus sulcate impressed elytral series (Fig. 16F) and aedeagal form, which

has the left paramere inserted close to the apex and the right paramere absent or reduced to a

spike, serve to distinguish them from adults of Hydraenida. In Hydraenida adults the pronotal

sides are straight in the rear, the elytral series are not sulcate impressed, and the aedeagus has

two long parameres which insert near the base.

Description. — Form: Generally elongate-oval, some adults somewhat truncate (Figs. 17A-H), moderately convex.

Size: Length 1.50 to 2.20 mm, width 0.68 to 1.05 mm. Most females slightly larger than males. Color Most adults black, a

few brown. Head: Moderately finely punctate to rugulose, generally with well developed microreticulation dorsally.

Interocular foveae moderately to well developed. Interocular tuberculi (ocelli) prominent. Clypeus transverse, parallel

sided to convergent anteriorly, some specimens with anterior angles deflexed. Labrum commonly with anterior margin

straight and upturned in males, remarkably so in some species; females shallowly emarginate. Maxillary palpus

moderately long, last three segments with approximate ratio of 2:1:2. Mentum trapezoidal, width at base approximately

equal to length; generally finely microreticulate; anterior margin straight. Genae swollen in midregion, grooved laterally

for reception of antennae. Antennae 1 1 segmented (6 + 5). Thorax: Pronotum with sides weakly to moderately sinuate at

rear, subcordate in shape. Anterior margin very slightly to moderately bisinuate in habitus view, trisinuate in anterior

view, anterior angles generally produced. Lateral depressions of most adults with moderately impressed fossula between

lateral depression and disc, fossula infrequently interrupted in midlength in form of two separate depressions ( reichardti );

area between fossula and side of pronotum generally slightly convex; sides crenulate. Disc with two U-shaped depressions,

well formed in most adults; posterior extremely shallow in few adults, generally well formed, in few adults joined to lateral

fossulae by shallow depression; anterior U-shaped depression extended to anterior margin of pronotum, deepest near

anterior margin in many adults. Posterior margin of pronotum arcuate to rear of midregion. Prosternum of most adults

elevated in midregion, not carinate; anterior coxae contiguous. Metasternum entirely hydrofuge pubescent, longitudinally

depressed in midline. Elytra: Disc with six rows of deeply impressed punctures between suture and humeri, each puncture

with prominent seta; rows weakly to markedly sulcate impressed. Intervals subcostate to costate, each with row of

setiferous punctures, punctures smaller than those of primary rows; first interval extended to apex in some adults,

terminated near apical 0.25 in others. Explanate margin moderately developed. Sides at anterior angles serrate. Abdomen:

Generally with basal four sterna plus anterior 0.25 of fifth sternum hydrofuge pubescent, remainder shiny. Hydrofuge

pubescence in few specimens restricted to first two sterna plus anterior 0.25 of third ( P . pentatenkta). Legs: Of moderate

Western Hemisphere Hydraenidae

49

length, rather stout, without apparent sexual dimorphism. Genitalia: Aedeagus with left paramere, although very small

in many males, inserted near apex; right paramere absent or reduced to spike-like process, inserted near apex.

Key to Western Hemisphere species of Parhydraenida

1 Hydrofuge pubescence of abdominal sterna restricted to basal two plus anterior

portion of third, remaining sterna shiny, very sparsely pubescent; Ecuador

(Fig. 17B) P. pentatenkta, new species, p. 59

V Hydrofuge pubescence on sterna 1-4 plus anterior portion of fifth; southeastern

Brazil 2

2 (1') Clypeus with parallel sides P . quadraticeps J. Balfour-Browne, p. 49

2 ' Clypeus with convergent sides 3

3 ( 2') Lateral fossulae of pronotum discontinuous, divided by elevated portion of

lateral depressions in form of deep depression near each angle of pronotum

(Figs. 15A,17C) P. reichardti J. Balfour-Browne, p. 52

3' Lateral fossulae not discontinuous 4

4 ( 3') Large, ca. 2.20 mm long; brownish; fifth abdominal sternum with transverse

band of short setae; clypeus markedly transverse (Figs. 17H, 19)

P. bubrunipes , new species, p. 51

4' Smaller, ca. 1.90 mm long or less; blackish; fifth abdominal sternum with

sparse, random setae; clypeus not markedly transverse 5

5 (4') Elytron with first interval (from suture) extended to just slightly before apex . 6

5' Elytron with first interval ending near posterior 0.25 7

6 ( 5 ) Pronotum with posterior U-shaped depression well developed (Figs. 17G,18D)

P. lambda , new species, p. 54

6' Posterior U-shaped depression absent or nearly imperceptible (Fig. 17E)

P. effeminata J. Balfour-Browne, p. 54

7 (50 Pronotal reliefs moderately shiny, punctate, not microreticulate (Figs. 12B,20B)

P. alida J. Balfour-Browne, p. 57

7' Pronotal reliefs dull, microreticulate 8

8 ( 70 Elytral rows deeply sulcate impressed; size larger, ca. 1.72 mm long; aedeagus

as illustrated (Figs. 17D, 20A) P. paralonga, new species, p. 56

8' Elytral rows shallowly sulcate impressed; size smaller, ca. 1.52 mm long;

aedeagus as illustrated (Figs. 17F,18B)

P. hygropetrica, new species, p. 57

1. Parhydraenida quadraticeps J. Balfour-Browne

(Figs. 17A,18C,162)

Parhydraenida quadraticeps J. Balfour-Browne, 1975:42. (holotype male, unique, deposited in MSP; type-locality:

Morretes, Parana, Brazil).

Diagnosis. - The parallel sided clypeus and aedeagal form serve as diagnostic features for

this species. The strongly upturned labrum of males is also distinctive.

Description. — Form: Slightly truncate, moderately convex (Fig. 17A). Size: Holotype 1.76 mm long, 0.78 mm

wide. Color Dorsum and venter black; legs, palpi and antennae brown. Head: Length 0.40 mm; width 0.52 mm. Frons

finely microreticulate, moderately coarsely punctate in middle, very sparsely pubescent; interocular foveae moderately

deep, subrugulose, width of each 0.66 distance between them; interocular tuberculi prominent; basomedial foveae absent.

Frontoclypeal suture evenly arcuate. Clypeus length 0.33 width, sides parallel; anterior angles prominent, rounded;

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Figs. 17A - H, Parhydraenida species, body outlines. (A) P. quadratieeps. (B) P. pentatenkta. (C) P. reichardti. (D) P.

paralonga. (E) P. effeminata. (F) P. hygropetrica. (G) P. lambda. (H) P. bubrunipes. (to same scale).

sculpture as frons. Labroclypeal suture slightly arcuate to rear. Labrum length nearly 0.33 width; anterior margin

straight, strongly upturned along entire width; sculpture as clypeus, although slightly more pubescent. Maxillary

palpomere 4 (apical) slightly longer than 2 (pseudobasal); palpomere 3 shorter than 2. Mentum trapezoidal, width at

base equal length, dull, finely microreticulate, very finely punctulate, anterior margin straight. Submentum finely

microreticulate, finely punctulate. Genae dull, finely microreticulate finely punctulate, swollen; grooved laterally for

reception of antennae. Postgena finely punctulate. Thorax: Pronotum length at midline 0.42 mm; maximum width (near

anterior 0.33) 0.68 mm. Anterior margin shallowly bisinuate. Lateral depressions slightly convex, coarsely punctate,

each puncture with short seta, finely microreticulate; sides crenulate, sinuate, not strongly produced laterally. Lateral

Western Hemisphere Hydraenidae

51

fossulae much deeper at anterior and posterior extremes, in form of four large foveae, posterior slightly larger than

anterior. Pronotal disc rounded, sculptured as lateral depressions, with anterior and posterior, wide U-shaped depression;

anterior depression extended to anterior margin; posterior depression with “arms” terminated on disc, clearly separated

from lateral fossulae by convex area on each side of disc. Posterior margin of pronotum arcuate posteriorly in

midregion. Prosternum elevated in midline, not carinate; coxae contiguous. Metasternum with large, longitudinal,

median depression; entirely hydrofuge pubescent. Elytra: Length 1.06 mm; maximum width (near midlength) 0.78 mm.

Disc shallowly depressed in middle, shiny, with six rows of large, deep punctures between suture and humeri, rows

sulcate impressed. Declivity in posterior 0.33. Intervals subcostate, width less than puncture width; each with row of

decumbent setae; first interval (from suture) extended to apex. Explanate margin moderately developed, terminated

near posterior 0.25. Apices slightly truncate. Abdomen: Basal four sterna with hydrofuge pubescence. Sternum 5

hydrofuge pubescent in anterior 0.33, remainder shiny. Sternum 6 shiny, very sparsely pubescent, posterior margin

arcuate to anterior in midline. Apical segment shiny, very sparsely pubescent. Legs: Moderately short and stout.

Genitalia: Male (Fig. 18C) (one examined).

Variation. - I have tentatively identified two females, with the following data, as P.

quadraticeps : Morretes, PR, km 37, Est. da Graciosa, Rio Cascata, 20-VI-1975,

H. & B. Reichardt. The pronotal and elytral features of these females agree very well with

those of the holotype. The sides of the clypeus, however, are slightly, but distinctly convergent,

not parallel as in the holotype male. The labrum is emarginate and not strongly upturned.

When series consisting of both sexes become available, they will probably reveal that the

differences in clypeal shape are sex-associated as are differences in the labrum.

Distribution (Fig. 162). - Known only from the type locality, Morretes, Parana, Brazil.

Remarks. - In the original description, J. Balfour-Browne (1975) states that the labrum has

the “anterior edge in males straight, strongly raised with a sharply impressed transverse

impression immediately behind....”. By way of clarification, although the markedly upturned

anterior margin forms a sharp angle with the remainder of the labrum, there is, however, no

transverse sulcus distinct from the sloping, basal portion of the labrum.

2. Parhydraenida bubrunipes new species

(Figs. 17H,19,162)

Type-locality. - Nova Teutonia, Santa Catarina, Brazil.

Type-specimen. - The holotype male (unique) is deposited in MCZ. Fritz Plaumann

collected this specimen in February, 1954.

Diagnosis. - Large size (2.20 mm long), brown color and strongly transverse clypeus are

diagnostic features for this species. Additionally, the holotype is unique among the known

species of Parhydraenida in possession of a transverse band of short setae on the fifth

abdominal sternum in males, at least; females are unknown.

Description. — Form: Elongate oval, moderately convex (Fig. 17H). Size: Holotype 2.20 mm long, 1.04 mm wide.

Color: Dorsum and venter dark brown; legs bright brown, contrasting well with venter; palpi teslaceus in basal 0.50, apical

0.50 dark brown. Head: Length 0.40 mm; width 0.66 mm. Frons in middle coarsely closely punctate, interstices shining,

very finely microreticulate, very sparsely pubescent; interocular foveae subrugulose, deep and large, width of each nearly

0.66 distance separating them; interocular tuberculi prominent; basomedial fovea absent. Frontoclypeal suture evenly

arcuate. Clypeus length slightly less than 0.33 width, sides slightly convergent, anterior margin arcuate to rear, anterior

angles prominent, rounded; surface subrugulose; viewed anteriorly fr-ont edge of clypeus markedly arcuate. Labrum length

0.33 width; anterior margin moderately upturned, arcuate in habitus view. Maxillary palpomere 4 (apical) slightly longer

than 2 (pseudobasal); palpomere 3 slightly less than 0.50 length of 4. Mentum trapezoidal, dull, finely microreticulate.

Submentum finely microreticulate. Genae swollen, shiny in midregion, microreticulate and grooved laterally for reception

of antennae. Postgena finely punctulate. Thorax: Pronotum length at midline 0.50 mm; maximum width (near midlength)

0.90 mm. Anterior margin bisinuate in habitus view, trisinuate in anterior view. Lateral depressions convex, coarsely

closely punctate, each puncture with a short but very apparent seta, finely microreticulate; sides crenulate, sinuate,

strongly produced laterally. Lateral fossulae sinuate, posterior portion slightly deeper than remainder. Pronotal disc

sculptured as lateral depressions, with anterior and posterior U-shaped depression; anterior U-shaped depression extended

to anterior margin, anterior extremes connected to anterior portion of lateral fossulae by shallow depression; posterior

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Perkins

U-shaped depression with “arms” terminated on disc, not connected to lateral fossulae. Posterior margin arcuate to rear

in midregion. Prosternum elevated in midline, not carinate; coxae contiguous. Metasternum broadly depressed in

midregion, hydrofuge pubescent except for very small, shiny area anterior to and between posterior coxae. Elytra:

Length 1.40 mm; maximum width (near midlength) 1.04 mm. Disc shiny, broadly depressed in middle, with six rows of

large, deep punctures between suture and humeri, rows sulcate impressed. Declivity extended through posterior 0.33.

Intervals costate, width slightly less than puncture width; first interval (from suture) extended to apices. Explanate

margin well developed, ending near apical 0.16. Apices slightly truncate. Abdomen: Basal four sterna with hydrofuge

pubescence. Sternum 5 hydrofuge pubescent in anterior 0.16, middle of sternum with transverse band of short setae in

very shallow depression. Sternum 6 shiny, sparsely pubescent, posterior margin arcuate to front in midregion. Apical

segment shiny, sparsely pubescent. Legs: Moderately long and stout. Genitalia: Male (Fig. 19) (one examined).

Distribution (Fig. 162). - Known only from the type locality of Nova Teutonia in the state

of Santa Catarina, Brazil.

Etymology. - Latin, bu (large) plus brun (brown) plus ipes (foot). I refer to large size and

brownish legs which contrast well with the remainder of the venter of the holotype.

3. Parhydraenida reichardti J. Balfour-Browne

(Figs. 1 0G, 1 1 C,D, 1 4B, 1 5 A-F, 1 6 A-F, 1 7C, 1 8 A, 1 48 B, 1 49E,F, 1 5 1 C, 1 52E,F, 1 53D,E, 1 62)

Parhydraenida reichardti J. Balfour-Browne, 1975: 42. (holotype male deposited in MSP; type-locality: Itatiaia, Rio de

Janeiro, Brazil).

Diagnosis. - The pronotum is very distinctive, having the depressions deeper than in adults

of other species. Additionally, the microreticulation of the pronotum is developed to the

extreme, totaly obscuring the punctation. P. reichardti adults are unique among the known

species of this genus in the form of the lateral fossulae, each of which is divided by an elevated

region to form a deep, comparatively large depression near each pronotal angle (Fig. 15A).

Description. — Form: Ovate, moderately convex (Fig. 17C). Size: Holotype 1.74 mm long, 0.80 mm wide. Color:

Dorsum and venter black; legs, palpi and antennae dark brown. Head: Length 0.38 mm; width 0.52 mm. Frons markedly

microreticulate, punctation obscured, very sparsely pubescent; interocular foveae deep and large, width of each equal to

distance between them; interocular tuberculi prominent; basomedial foveae absent. Frontoclypeal suture evenly arcuate.

Clypeus length 0.33 width, markedly microreticulate. Labroclypeal suture slightly arcuate to rear. Labrum length 0.14

width; anterior margin arcuate in habitus view, moderately upturned. Maxillary palpomeres 2 (pseudobasal) and 4

(apical) subequal in length; palpomere 3 0.50 length of 4. Mentum trapezoidal, width at base equal length, dull, finely

microreticulate, anterior margin straight. Submentum finely microreticulate. Genae swollen, dull, finely microreticulate,

grooved laterally for reception of antennae. Postgena finely punctulate. Thorax: Pronotum length at midline 0.42 mm;

maximum width (near midlength) 0.70 mm. Anterior margin deeply bisinuate. Lateral depressions convex in middle,

markedly microreticulate, setae indistinct; sides crenulate, sinuate, markedly produced laterally. Lateral fossula distinctly

divided by convex portion of lateral depression in form of very deep, large fovea at posterior and anterior. Pronotal disc

markedly microreticulate, punctation obscured, with anterior and posterior U-shaped depression joined by extremely

shallow depression; anterior U-shaped depression with distinctive, deep fovea at each anterior extreme, these foveae

separated, from the anterior foveae of lateral depressions by ridge; posterior U-shaped depression with anterior extremes

contiguous with posterior fovea of lateral depressions. Prosternum elevated in midline; coxae contiguous. Metasternum

totally hydrofuge pubescent; middle region shallowly depressed. Elytra: Length 1.10 mm; maximum width (near

midlength) 0.80 mm. Disc moderately shiny, with six rows of large, deep punctures between suture and humeri, rows

sulcate impressed. Declivity extended through posterior 0.33. Intervals costate, width less than puncture width; each with

row of decumbent setae; first interval (from suture) ending near apical 0.25. Explanate margin moderately developed

ending near posterior 0.25. Apices slightly truncate. Abdomen: Basal four sterna with hydrofuge pubescence. Sterna 5, 6

and 7 subnitid, sparsely pubescent. Legs: Moderately short and stout. Genitalia: Male (Fig. 18A) (seven examined).

Variation. - Specimens from Santa Catarina have the pronotal depressions deeper than

specimens from Sao Paulo. Females have the labrum emarginate anteriorly and not strongly

upturned.

Natural History. - Adults have been collected in hygropetric habitats.

Distribution (Figs. 14B.162). - Presently known to be distributed in the mountains of

southeastern Brazil from the state of Espirito Santo south to the state of Santa Catarina.

Sixteen specimens have been studied in addition to the holotype (see Appendix A).

Western Hemisphere Hydraenidae 53

Figs. 18A - D, Aedeagi of Parhydraenida holotypes. (A) P. reichardti. (B) P. hygropetrica. (C) P. quadraticeps. (D) P.

lambda.

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4. Parhydraenida lambda new species

(Figs. 17G,18D,162)

Type-locality. - Jaguariaiva, 950 meters, Parana, Brazil.

Type-specimen. - The holotype male (unique) is deposited in MSP. This specimen was

collected by Reichardt and Martins, August 30, 1974.

Diagnosis. - The pronotum has the sides strongly arcuate posteriorly and fossulae and

U-shaped depressions moderately deep. The first elytral interval continues posteriorly to near

the apices. The aedeagus is highly diagnostic.

Description. — Form: Ovate, moderately convex (Fig. 17G). Size: Holotype 1.88 mm long, 0.84 mm wide. Color:

Dorsum and venter black; legs, palpi and antennae dark brown. Head: Length 0.38 mm; width 0.50 mm. Frons in middle

coarsely, closely punctate, microreticulation well developed in punctures, less apparent on interstices; very sparsely

pubescent; interocular foveae deep and large, subrugulose, width of each nearly 0.66 distance separating them; interocular

tuberculi prominent; basomedial fovea absent. Frontoclypeal suture evenly arcuate. Clypeus length slightly less than 0.50

width, punctation obscured by well developed microreticulation. Labroclypeal suture straight. Labrum length 0.33 width;

anterior margin strongly upturned, arcuate in habitus view. Maxillary palpomeres 2 (pseudobasal) and 4 (apical) subequal

in length; palpomere 3 0.50 length of 2. Mentum trapezoidal, width at base equal length, dull, finely punctulate, finely

microreticulate, anterior margin straight. Submentum finely microreticulate. Genae swollen, shiny in midregion, dull and

grooved for reception of antennae laterally. Postgena finely punctulate. Thorax: Pronotum length at midline 0.42 mm;

maximum width (near anterior 0.33) 0.68 mm. Anterior margin bisinuate in habitus view. Lateral depressions convex,

coarsely closely punctate, microreticulate within punctures, each puncture with a short but very apparent seta; sides

crenulate, sinuate, moderately produced laterally. Lateral fossulae sinuate, slightly deeper at anterior and posterior than in

midregion. Pronotal disc sculpture as lateral depressions, with anterior and posterior U-shaped depression; anterior

U-shaped depression extended to anterior margin, shape of anterior pronotal margin trisinuate when viewed from the

front; posterior U-shaped depression with “arms” terminated on disc, not connected to lateral fossulae. Posterior margin of

pronotum arcuate to posterior in midregion. Prosternum elevated in midline, not carinate; coxae contiguous. Metasternum

with longitudinal, oval depression in midline; this depression surrounded by non-pubescent area, (but I believe the

hydrofuge hairs are usually present here, being abraded in holotype). Elytra: Length 1.14 mm; maximum width (near

midlength) 0.84 mm. Disc shallowly depressed in middle, shiny, with six rows of large, deep punctures between suture and

humeri, rows deeply sulcate impressed. Origin of declivity near posterior 0.33. Intervals subcostate, width less than

puncture width, each with row of decumbent setae; first interval (from suture) extended to apices. Explanate margin well

developed, terminated near posterior 0.17. Apices rounded. Abdomen: Basal four sterna with hydrofuge pubescence (some

abraded). Sternum 5 pubescent in anterior 0.25, remainder shiny. Sterna 6 and 7 shiny, sparsely pubescent. Legs:

Moderately short and stout. Genitalia: Male (Fig. 18D) (one examined).

Natural History. - Hans Reichardt (in lift.) gives the following information concerning the

type locality: “in typical hygropetric habitat, collected together with different species of

Torridincolidae, genus Ytu ”.

Distribution. (Fig. 162). - Known only from the type locality at Jaguariaiva in the state of

Parana, Brazil.

Etymology. - The aedeagus resembles the Greek letter lambda.

5. Parhydraenida effeminata J. Balfour-Browne

(Figs. 14B,17E,162)

Parhydraenida effeminata J. Balfour-Browne, 1975:43 (holotype female deposited in MSP; type locality: Nova Petropolis,

Rio Grande do Sul, Brazil).

Diagnosis. - The pronotum is comparatively shiny, with fossulae and U-shaped depressions

extremely shallow, especially the barely perceptible posterior U-shaped depression. The first

elytral interval is extended the full length of the elytron. The body form is rather distinctive, as

a comparison between the illustrations will reveal (Fig. 17E).

Description. — Form: Ovate, moderately convex (Fig. 14B). Size: Holotype 1.84 mm long, 0.82 mm wide. Color:

Dorsum and venter black; legs, palpi and antennae light brown. Head: Length 0.38 mm; width 0.54 mm. Frons in middle

moderately coarsely, closely punctate, punctures microreticulate, interstices obsoletely so; sparsely pubescent; interocular

Western Hemisphere Hydraenidae

55

Fig. 1 9. Aedeagus of Parhydraenida bubrunipes, holotype.

foveae shallow and broad, width of each equal to intervening distance; interocular tuberculi not prominent; basomedial

fovea absent. Frontoclypeal suture evenly arcuate. Clypeus width 2.5 times length, sides convergent, sculpture as middle

of frons. Labroclypeal suture straight. Labrum length 0.33 width; anterior angles rounded; middle of anterior margin

narrowly, moderately deeply emarginate. Maxillary palpomere 4 (apical) wider than a tarsal apex, slightly longer than

palpomere 2 (pseudobasal); palpomere 3 slightly less than 0.50 length of 4. Mentum trapezoidal, width at base equal

length, microreticulate, dull, anterior margin straight. Submentum evenly, finely punctulate. Genae swollen, dull, finely

punctulate, grooved laterally for reception of antennae. Postgena finely punctulate. Thorax: Pronotum length at midline

0.40; maximum width (near anterior 0.33) 0.66 mm. Anterior margin bisinuate. Lateral depressions deflexed slightly at

anterior angles, not convex, moderately coarsely, very closely punctate, each puncture with short but very apparent seta;

Quaest. Ent., 1980, 16 (1,2)

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Perkins

strongly microreticulate in punctures, interstices shiny, very obsoletely microreticulate; sides crenulate, sinuate, not

markedly produced laterally. Lateral fossulae sinuate, shallow for entire length. Pronotal disc sculptured as lateral

depressions, with very shallow anterior and posterior U-shaped depression, latter nearly imperceptible; anterior

U-shaped depression deepest and well marked at anterior margin. Posterior margin very slightly arcuate to rear in

midregion. Prosternum slightly elevated in midline, not carinate; coxae contiguous. Metasternum entirely hydrofuge

pubescent, depressed in midregion. Elytra: Length 1.16 mm; maximum width (near midlength) 0.82 mm. Disc shiny,

with six rows of large, deep punctures between suture and humeri, rows very shallowly sulcate impressed. Declivity

beginning near posterior 0.33. Intervals subcostate, width less than puncture width; each with row of decumbent setae;

first interval (from suture) extended to apices. Explanate margin moderately developed. Apices very slightly dehiscent

at suture. Abdomen: Basal four sterna with hydrofuge pubescence. Sternum 5 hydrofuge pubescent in anterior 0.25,

remainder shiny. Sternum 6 shiny, posterior margin strongly arcuate to front, sparsely pubescent. Sternum 7 ovate,

shiny, sparsely pubescent. Legs: Moderately short and stout. Genitalia: Male unknown.

Distribution. (Figs. 14B, 162). - Presently known from the states of Rio Grande do Sul and

Santa Catarina, Brazil. Refer to J. Balfour-Browne (1975) for locality data.

6. Parky dr aenida paralonga new species

(Figs. 17D, 20A,162)

Type-locality. - Campos do Jordao, 1650 meters, Sao Paulo, Brazil.

Type-specimens. - The holotype male and allotype with identical data are deposited in

MSP. Paratypes from the same locality, all females, are deposited in MSP (15), USNM (2)

and PDP (2). These specimens were collected by Hans and Bartyra Reichardt, January, 1976.

Diagnosis. - Adults are quite similar externally to those of P. hygropetrica in that both

groups have the first elytral interval ending at the posterior 0.25. Additionally, pronota of both

groups have dull reliefs and rather shallow depressions. P. paralonga adults differ in larger size

(ca. 1.75 vs. 1.55 mm long), body form (Figs. 17D,F), more deeply sulcate impressed elytra and

aedeagal form (Figs. 18B,20A).

Description. — Form: Ovate, moderately convex (Fig. 17D). Size: Holotype 1.72 mm long, 0.76 mm wide. Color

Dorsum and venter black; legs, palpi and antennae dark brown. Head: Length 0.34 mm; width 0.48 mm. Frons in middle

coarsely punctate, markedly microreticulate, very sparsely pubescent; interocular foveae deep, subrugulose, width of each

nearly 0.50 distance separating them; interocular tuberculi prominent; basomedial fovea absent. Frontoclypeal suture

evenly arcuate. Clypeus length 0.50 width, markedly microreticulate, sides convergent. Labroclypeal suture straight.

Labrum length 0.33 width; anterior margin moderately upturned, arcuate in habitus view. Maxillary palpomere 2

(pseudobasal) and 4 (apical) subequal in length: palpomere 4 swollen; palpomere 3 0.50 length of 2. Mentum trapezoidal,

dull, finely microreticulate; anterior margin straight. Submentum evenly, finely punctulate, punctures contiguous. Genae

swollen, dull, finely punctulate, grooved laterally for reception of antennae. Postgena finely punctulate. Thorax: Pronotum

length at midline 0.40 mm; maximum width (near anterior 0.33) 0.64 mm. Anterior margin bisinuate. Lateral depressions

slightly convex, coarsely punctate, markedly microreticulate; sides slightly crenulate, sinuate not markedly produced

laterally. Lateral fossulae slightly sinuate, posterior 0.50 slightly deeper than remainder. Pronotal disc sculptured as

lateral depressions, with posterior and anterior U-shaped depression; anterior U-shaped depression wider than posterior,

extended to anterior margin, deepest near margin; posterior U-shaped depression with “arms” terminated on disc not

extended to lateral fossulae. Posterior margin arcuate to rear in midregion. Prosternum elevated in midline, not carinate;

coxae contiguous. Metasternum entirely pubescent, depressed in midregion. Elytra: Length 1.08 mm; maximum width

(near midlength) 0.76 mm. Disc moderately dull, with six rows of large deep punctures between suture and humeri, rows

deeply sulcate impressed. Declivity not well defined. Intervals subcostate, width less than puncture width; first interval

(from suture) ended near apical 0.25. Explanate margin moderately developed, ending near apical 0.20. Apices slightly

truncate. Abdomen: Basal four sterna with hydrofuge pubescence. Sternum 5 hydrofuge pubescence in anterior 0.25,

remainder shiny. Sterna 6 and 7 shiny, sparsely pubescent. Legs: All legs moderately short and stout. Genitalia: Male

(Fig. 20A) (one examined).

Variation. - Females have the labrum emarginate and not strongly upturned.

Distribution. - (Fig. 162) Known only from the type-locality at Campos do Jordao in the

state of Sao Paulo, Brazil.

Etymology. - Latin, para (beside) plus longa (long). This name refers to the single long

paramere of the aedeagus.

Western Hemisphere Hydraenidae

57

7. Parhydraenida alida J. Balfour-Browne

(Figs. 12B,20B,162)

Parhydraenida alida J. Balfour-Browne, 1975: 40. (holotype male deposited in MSP; type-locality: Barra da Tejuca, Rio

de Janeiro, Guanabara, Brazil).

Diagnosis. - Combination of small size (about 1.46 mm long), shiny, non-microreticulate

pronotal reliefs, first elytral interval terminated near the posterior 0.25, and aedeagal form

serve as diagnostic characteristics. Similarities in aedeagal structure (Figs. 18B, 20B) and body

size and form (Figs. 12B,17F) indicate that P. alida and P. hygropetrica form a sister-species

pair. Adults of the two species are differentiated externally by the pronotal reliefs, which are

non-microreticulate and shiny in P. alida specimens; dull and microreticulate in P.

hygropetrica specimens.

Description. — Form: Ovate, moderately convex (Fig. 12B). Size: Holotype 1.46 mm long, 0.64 mm wide. Color

Dorsum and venter black; legs, palpi and antennae brown. Head: Length 0.30 mm; width 0.42 mm. Frons in middle

moderately coarsely punctate, microreticulate in punctures, interstices obsoletely so, moderately shiny; very sparsely

pubescent; interocular foveae strongly microreticulate, deep and large, width of each nearly 0.66 distance separating them;

interocular tuberculi prominent; basomedial fovea absent. Frontoclypeal suture evenly arcuate. Clypeus length 0.33 basal

width, sides convergent, microreticulate, punctures somewhat obscured. Labroclypeal suture straight. Labrum length 0.25

width; anterior border shallowly emarginate, strongly upturned. Maxillary palpomere 2 (pseudobasal) and 4 (apical)

subequal in length; palpomere 3 0.50 length of 2. Mentum trapezoidal, width at base equal length, finely microreticulate,

anterior margin straight. Submentum finely microreticulate. Genae swollen, dull, finely microreticulate, grooved laterally

for reception of antennae. Postgena finely punctulate. Thorax: Pronotum length at midline 0.36 mm; maximum width

(near anterior 0.33) 0.54 mm. Anterior margin slightly bisinuate. Lateral depressions with edges rounded but remainder

not convex, with short but very apparent setae; sides crenulate, sinuate, not markedly produced laterally. Lateral fossulae

much broader in anterior than posterior, shining, finely microreticulate, setae much less apparent than those of lateral

depressions. Pronotal disc with well developed anterior and posterior U-shaped depressions, anterior broadest and extended

to anterior margin; posterior U-shaped depression ended on disc, not connected to lateral fossulae. Posterior margin

arcuate to rear in midregion. Prosternum elevated in midline, not carinate; coxae contiguous. Metasternum entirely

hydrofuge pubescent, median region depressed. Elytra: Length 0.88 mm; maximum width (near midlength) 0.64 mm. Disc

moderately shiny, with six rows of moderately large, deep punctures between suture and humeri, rows sulcate impressed.

Origin of declivity near posterior 0.33. Intervals subcostate, width slightly less than puncture width; each with row of

decumbent setae; first interval (from suture) terminated at apical 0.25. Explanate margin moderately developed. Apices

slightly truncate. Abdomen: Basal four sterna plus anterior 0.33 of sternum 5 hydrofuge pubescent. Posterior 0.66 of

sterna 5 and 6 subnitid, sparsely pubescent. Legs: Relatively stout. Genitalia: Male (Fig. 20B) (one examined).

Variation. - The labrum is more deeply emarginate in females, the edge of the emargination

being upturned slightly. Maxillary palpomere 4 is larger in males, the lateral surface more

arcuate, the medial sinuate; in females the medial is slightly arcuate.

Distribution. - (Fig. 162) Presently known only from the state of Rio de Janeiro, Brazil.

8. Parahydraenida hygropetrica new species

(Figs. 17F,18B,162)

Type-locality. - Santa Teresa, Espirito Santo, Brazil.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in MSP. These specimens and four paratypes from the same locality (two MSP; one USNM;

one PDP) were collected by S. Vanin and O. Flint, April 23, 1977.

Diagnosis. - Small size (about 1.55 mm long), dull, microreticulate pronotal reliefs, first

elytral interval ending near posterior 0.25, and aedeagal form (Fig. 18B) serve as diagnostic

characteristics. The pronotal microreticulation is similar to that of P. paralonga adults; refer to

the diagnosis of that species for further comments. Body form and size plus aedeagal structure

indicate that P. hygropetrica and P. alida are sister-species. The pronotal reliefs of P. alida

adults, however, are shiny, non-microreticulate.

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Figs. 20A - B, Aedeagi of Parhydraenida holotypes. (A) P. paralonga. (B) P. alida.

Western Hemisphere Hydraenidae

59

Description. — Form: Ovate, moderately convex (Fig. 17F). Size: Flolotype 1.52 mm long, 0.68 mm wide. Color:

Dorsum and venter black; legs, palpi and antennae dark brown. Head: Length 0.30 mm; width 0.44 mm. Frons

microreticulate, moderately coarsely punctate, punctures obscured by microreticulation, very sparsely pubescent;

interocular foveae deep and large, width of each nearly 0.66 distance separating them; interocular tuberculi prominent;

basomedial fovea absent. Frontoclypeal suture evenly arcuate. Clypeus length 0.33 width, microreticulate, sides

convergent. Labroclypeal suture straight. Labrum length 0.25 width; anterior margin upturned, arcuate in habitus view.

Maxillary palpomere 4 slightly swollen, slightly longer than palpomere 2; palpomere 3 shorter than 2. Mentum

trapezoidal, width at base equal length, shining, very finely microreticulate, anterior margin straight. Submentum shiny,

finely punctulate. Genae swollen, very shiny in midregion, dull and microreticulate laterally; grooved laterally for

reception of antennae. Thorax: Pronotum length at midline 0.36 mm; maximum width (near anterior 0.33) 0.56 mm.

Anterior margin very shallowly bisinuate. Lateral depressions very slightly convex, microreticulate, coarsely closely

punctate; sides crenulate, sinuate, moderately produced laterally. Lateral fossulae slightly sinuate, of equal depth along

entire length. Pronotal disc microreticulate, moderately coarsely, closely punctate, with anterior and posterior U-shaped

depression; anterior U-shaped depression extended to anterior margin; posterior U-shaped depression with “arms” ended

on disc, not connected to lateral fossulae. Posterior margin of pronotum arcuate posteriorly in midregion. Prosternum

elevated in midregion; coxae contiguous. Metasternum entirely hydrofuge pubescent; midline with narrow groove. Elytra:

Length 0.88 mm; maximum width (near midlength) 0.68 mm. Disc moderately flat, shiny, with six rows of large, deep

punctures between suture and humeri, rows shallowly sulcate impressed. Declivity origin near posterior 0.33. Intervals

subcostate, width less than puncture width; each with row of decumbent setae; first interval(from suture) ended at apical

0.25. Explanate margin moderately developed, ended near posterior 0.17. Apices rather broad, arcuate. Abdomen: Basal

four sterna with hydrofuge pubescence. Sternum 5 pubescent in anterior 0.25, remainder shiny. Sterna 6 and 7 shiny,

moderately produced posteriorly. Legs: Moderately short and stout. Genitalia: Male (Fig. 18B) (five examined).

Variation. - The labrum is emarginate and not markedly upturned in females. Other sexual

dimorphism includes size and shape of maxillary palpomere 4. In males this article is longer

and wider than in females; the width being greater than the apical width of the last tarsomere

in males, less than this width in females.

Natural History. - The type-series were collected from a hygropetric habitat.

Distribution. - (Fig. 162). Known only from the type-locality at Santa Teresa in the State of

Espirito Santo, Brazil.

Etymology. - Latin, hygro (wet) plus petrus (rock).

9. Parhydraenida pentatenkta new species

(Figs. 17B,50A,162)

Type-locality. - 38 km E. of Portoviejo, Manabi Province, Ecuador.

Type-specimen. - The holotype female (unique) is deposited in USNM. This specimen was

collected by P. Spangler, A. Langley and J. Cohen, May 11, 1975.

Diagnosis. - Adults of this species are unique in reduction of hydrofuge pubescence of the

abdomen to the first two sterna plus the anterior 0.33 of sterna 3. The remaining sterna are

shiny and with very sparse, non-hydrofuge hairs. Adults of all other currently known species in

the genus Parhydraenida have the first four sterna plus the anterior portion of sternum 5

hydrofuge pubescent. P. pentatenkta adults are also quite distinctive dorsally, as the pronotum

is comparatively large and quite transverse (Fig. 17B). The deflexed anterior clypeal angles and

labrum are worthy of note.

Description. — Form: Ovate, moderately convex (Fig. 17B). Size: Holotype 1.56 mm long, 0.80 mm wide. Color:

Brown. Head: Length 0.30 mm; width 0.54 mm. Frons rugulose, strongly microreticulate, very sparsely pubescent;

interocular foveae deep and large, width of each nearly equal distance separating them; interocular tuberculi prominent;

basomedial fovea very slightly apparent. Frontoclypeal suture evenly arcuate. Clypeus length 0.33 width, finely rugulose,

moderately pubescent, anterior angles deflexed. Labroclypeal suture straight in habitus view; viewed anteriorly it is

arcuate due to deflexed anterior angles of clypeus. Labrum length 0.33 width; very markedly deflexed, nearly at right

angle to major plane of clypeus; anterior margin emarginate and prominently pubescent. Maxillary palpus very short;

palpomeres 2 and 4 subequal in length, palpomere 3 0.50 length of 2. Mentum markedly punctulate, pubescent.

Submentum punctulate. Genae swollen, dull, punctulate, grooved laterally for reception of antennae. Postgena punctulate.

Thorax: Pronotum length at midline 0.42 mm; maximum width (near anterior 0.33) 0.76 mm. Anterior margin bisinuate,

Quaest. Ent., 1980, 16 (1,2)

60

Perkins

anterior angles produced. Lateral depressions broad, very slightly convex, rugulose; sides crenulate, very slightly sinuate

at posterior, moderately produced laterally. Lateral fossulae slightly deeper at anterior and posterior than in midregion.

Pronotal disc rugulose, with anterior and posterior U-shaped depression connected by narrow median groove. Posterior

margin arcuate to rear in midregion. Prosternum slightly elevated in midregion. Metasternum hydrofuge pubescent;

longitudinally depressed in middle. Elytra: Length 1.04 mm; maximum width (near midlength) 0.80 mm. Disc dull,

with six rows of large, deep punctures between suture and humeri, rows deeply sulcate impressed. Declivity origin near

posterior 0.33. Intervals costate, width less than puncture width; each with row of decumbent setae; first interval (from

suture) ended near posterior 0.20. Explanate margin moderately developed, markedly serrate in anterior 0.20. Apices

slightly truncate. Abdomen: Basal two sterna plus anterior 0.33 of sternum 3 hydrofuge pubescence, remainder shiny,

very sparsely pubescent. Legs: Short and stout. Genitalia: Male unknown.

Natural History. - The following label description accompanies the holotype: “collected in splash zone at

waterfall”.

Distribution. - (Fig. 50A) Known only from the type-locality near Portoviejo in western

Ecuador.

Etymology. - Greek, penta (five) plus tenkta (wettable). This name refers to the five

abdominal sterna which lack hydrofuge pubescence and are, therefore, wettable.

GENUS HYDRAENA KUGELANN

Hydraena Kugelann 1794:579 (type-species: Hydraena riparia Kugelann 1794:579). - d’Orchymont, 1916:96. -

d’Orchymont, 1923:33. - Knisch, 1924:33. - F. Balfour-Browne, 1958:178. - Janssens, 1965).

Discussion. - Hydraena is markedly diverse, the total number of species described for the

world being about 400, of which 95 are now known for the Western Hemisphere. It is the most

diverse genus in the family, Ochthebius being second, with about 300 species. Judging from the

number of new species described in this paper and those by Janssens (1965, 1972) and Zwick

(1977), one must suppose that the actual number of Hydraena species is considerably greater

than the present figure.

Members of Hydraena are on all continents, but are notably absent from New Zealand

(d’Orchymont, 1936a), where they are apparently replaced by members of Orchymontia Broun

1919 (d’Orchymont 1936a; Zwick, 1975). In the Western Hemisphere, Hydraena members are

in most areas, being absent from Alaska, the Great Plains region of the United States, Chile,

Uruguay, and all of Argentina except extreme northernmost (Fig. 160).

Current data indicate that the greatest concentration of species is in California and

Mexico-Central America, but more field work remains to be done, especially in South America.

Distributional considerations are discussed in more detail in the section on zoogeography.

During the 1800’s, students of the genus organized the species into a number of subgenera,

based in large part upon rather insignificant and unstable characteristics. Consequently, most

of these subgenera have been found to be of species-group rank when studied rigorously.

Rey (1884) was the first worker to use the number of elytral striae between the suture and

humeral callus as a means of subgeneric separation. Species with more than six striae (usually

10) he placed in Hydraena (sensu stricto ), whereas those with six were placed into his

subgenera Haenydra or Hadrenya , depending upon shape of metasternal plaques.

Kuwert (1888) erected the subgenera Taenhydraena, Phothydraena, Hoplydraena,

Holcohydraena, Sphaenhydraena and Grammhydraena. These names were either new for

groups already proposed by Rey (F. Balfour-Browne, 1958), or the groups were based upon

insignificant features.

D’Orchymont (1930) was the first to discover that aedeagi of males of species with six

elytral striae lacked parameres, whereas males of species with more than six striae had

Western Hemisphere Hydraenidae

61

parameres. On this basis he accepted Rey’s (1884) Hydraena (sensu stricto ) (with parameres)

and Haenydra (lacking parameres). He also recognized Kuwert’s (1888) subgenus

Phothydraena , which was erected for the single species H. testacea because of the unusually

large punctures at the margin of the elytron in adults. This appears to be inconsistent, as the

aedeagus and elytral striae of H. testacea clearly place it in Hydraena (sensu stricto).

In a paper on the phylogeny of Hydraena , d’Orchymont (1936a) tabulated those characters

which he deemed significant, and recognized the subgenera Hydraena ( sensu stricto ),

Holcohydraena, Taenhydraena, Phothydraena and Haenydra.

Kuwert (1888) erected Holcohydraena for Hydraena rugosa Mulsant 1884, of Europe and

the Iberian Peninsula, because of lack of metasternal plaques. Adults of some species of New

World Hydraena also lack plaques, but these species are related to others from this

geographical area whose adults have plaques. Plaque loss occurs in species which are of

different lineages and is obviously not of subgeneric significance. Zwick (1977) has found the

same to be true for Australian Hydraena.

Kuwert’s (1888) Taenhydraena, which contains only Hydraena exarata Kiesenwetter 1865

of the Iberian Peninsula, was established because of the elevated alternate elytral intervals of

adults of that species. Adults of Hydraena alternata from Mexico also have this trait, but this

species is probably of a different lineage, the similarities of the two being convergent. Aedeagi

of H. exarata males (d’Orchymont, 1936b) do not indicate any obvious relationship to H.

alternata. Further study is needed here, but I suspect that the characteristics upon which

Taenhydraena is based will eventually be considered of only species-group significance.

More recently, Janssens (1972), in a paper describing one new species from Vietnam, two

from Ghana, and one from Paraguay, has proposed a new genus, which he names

Hydraenopsis. The principal basis for this proposed taxon is form of the aedeagus, more

specifically, location of the insertion of the parameres. He states, “Parmi ces caracteres, l’un

m’a paru suffisant pour creer une coupe generique groupant la majorite des especes

intertropicales connues et prenant le nom d’ Hydraenopsis n. g. II s’agit de la structure des

genitalia: au lieu d’etre attaches a la base, les parameres du nouveau genre, plus courtes que

chez Hydraena (sensu stricto), sont attaches au centre du corps basal, ainsi qu’on le verra dans

les figures 2, 4 et 5.”

Emphasizing form of the aedeagus further, he states, “....le caractere determinant pour

conclure a la validite du nouveau genre Hydraenopsis reside dans la structure tres particulere

des genitalia et notamment dan la mode d’insertion de parameres.”

I have found during this study that insertion of the parameres varies greatly from species to

species in the Neotropical fauna, and virtually all intermediate types are seen between those

whose males have parameres inserted at the base and those whose males have parameres near

the apex. For instance, one could cite the following species as examples in a sequence of from

base to apex insertion: chiapa - scintillabella - alternata - maureenae - orcula - colymba -

youngi - paeminosa.

Further, males of several species have one paramere closer to the base than the other, some

examples being trinidensis, turrialba, spangleri and browni. Clearly, this great variation of

paramere insertion precludes using this character for generic separation.

The following external characteristics were cited by Janssens (1972) as significant, “....la

form du pronotum et l’article apical des palpes maxillaires toujours depourvu de noircessement

a l’apex sont des caracteres dont la Constance corrobore la stabilite du nouveau genre qu’on

reconnaitra ainsi assez commodement a premiere vue.” These characteristics are also highly

Quaest. Ent., 1980, 16 (1,2)

62

Perkins

variable within neotropical Hydraena, even within the aggregate of species herein presented as

the leechi Group.

Consequently, I do not recognize Hydraenopsis Janssens as a valid genus, and consider all of

the Hydraena in the Western Hemisphere as members of Hydraena (sensu stricto). However,

relative ranking of primarily temperate vs. primarily tropical components of Hydraena would

require additional thought if and when constant differentiating characteristics were elucidated.

Relative to amount of published data regarding Palearctic Hydraena , available information

on New World forms is scant indeed. This is due in large part to the lack of material available

to earlier workers such as d’Orchymont who, in 1923, had only about 100 specimens

representing the nine species known at that time. Through the efforts of recent American

students of aquatic Coleoptera, most notably Hugh B. Leech and Paul J. Spangler, specimens

have gradually accumulated in collections; as a result of these efforts, more than 10,000

specimens were available for this study.

Publications concerning Western Hemisphere Hydraena began with Kiesenwetter’s

description of H. pennsylvanica and H. marginicollis in 1849. Subsequent to that work, 16 taxa

have been described in the following sequence: H. punctata LeConte 1855; H. longicollis, H.

puncticollis , H. sordida Sharp, all 1882; H. angulicollis Notman 1921; H. grouvellei, H.

sahlbergi, H. germaini, H. vandykei, H. guadelupensis, all d’Orchymont 1923; Hydraena

needhami d’Orchymont 1929; H. plaumanni d’Orchymont 1937; H. insularis d’Orchymont

1945; Hydraena vandykei niger Hatch 1965; H. paraguayensis Janssens 1972.

Despite relatively few descriptions, attempts to obtain types did not meet with complete

success. Although a number of European museums were contacted, Kiesenwetter’s types of H.

pennsylvanica and H. marginicollis were not found. D’Orchymont (1945), despite his extensive

knowledge of the genus, was apparently unable to find the type of H. marginicollis as he based

his concept of the species upon a specimen in the Institut royal des Sciences Naturelles de

Belgique collection labelled “cotype?” of H. marginicollis. The above suggests that the types of

H. marginicollis have been destroyed or irrevocably lost. However, combination of small size

and type locality (“Westindien” and New Orleans) leave little doubt as to the identify of H.

marginicollis. To firmly establish the identity of H. marginicollis a neotype is designated

herein. Likewise, I believe that the single type-specimen of H. pennsylvanica has reached a

similar fate; therefore a neotype is designated to insure stability.

Efforts to obtain holotypes of d’Orchymont’s H. insularis , H. grouvellei and H. germaini

also failed. However, paratypes of each of thse species have been studied and there is no

confusion concerning their identities. I believe that futher search at European museums (where

I have already enquired) will result in location of these holotypes, therefore no lectotypes are

designated for these species.

The type series of Sharp’s Neotropical species H. longicollis , H. puncticollis , and H.

sordida have been studied and lectotypes are designated for each.

Holotypes of the following species have been seen: H. sahlbergi d’Orchymont; ; H.

plaumanni d’Orchymont; H. guadelupensis d’Orchymont; ; H. punctata LeConte; H.

angulicollis Notman; H. needhami d’Orchymont; H. vandykei d’Orchymont; H. vandykei

niger Hatch.

The holotype and two paratypes of H. paraguayensis Janssens were requested from the

Institut royal des Sciences Naturelles de Belgique (through E. Janssens). However, when the

material was received, it was found to contain the pin with holotype label and locality label, but

the specimen was no longer glued to the card. A search of the box proved fruitless. Therefore, a

Western Hemisphere Hydraenidae

63

lectotype is herein designated.

Of the 18 previously described species, only one instance of new synonomy was encountered.

H. needhami d’Orchymont 1929 was found to be conspecific with H. punctata 1855.

Pronotal features. - The major relief features of Hydraena pronota (Fig. 2 1C) consist of

anteroexternal foveolae (AEF), margins (M), posteroexternal foveolae (PEF) and

posterointernal fovelae (PIF). In adults of certain species, such as H. circulata (Fig. 21C), the

antero- and posteroexternal foveolae are markedly confluent and form a longitudinal depression

similar to the “lateral fossulae” of Ochthebius (Fig. 98A). In adults of other species, such as H.

bituberculata (Fig. 3 1C) and H. cuspidicollis (Fig. 48C), the antero- and posteroexternal

foveolae are distinct, although joined by a shallow depression. In adults of species of the

marginicollis Group, most pronotal depressions are obsolete, only the anteroexternal foveolae

being apparent (e.g. marginicollis , (Fig. 54C)).

Diagnosis. - Elongate maxillary palpi (Fig. 148C) readily distinguish Hydraena adults from

those of all other Western Hemisphere Hydraenidae except Spanglerina. From Spanglerina

adults, Hydraena adults are distinguished by 1) the less markedly angulate pronotum

(cf. Figs. 21C,54C,65E), which lacks a median ridge or anterointernal foveolae, 2) absence of

foveae near the anterior margin of the labrum (cf. Figs. 54D,65F), 3) procoxae not as widely

separated as mesocoxae (cf. Figs. 21D,E,65D), 4) without metacoxae widely separated

(cf. Figs. 21D,65C), and 5) males with aedeagus of a different basic plan

(cf. Figs. 22A,45A,67A-D).

Description. — Form: Generally elongate and relatively depressed, adults of a few species elongate-oval. Size:

Length about 1.00-2.00 mm, width about 0.47-0.85 mm. Females generally larger than males. Color: Adults of some

species black, some brown, a few with testaceous or ochraceous legs contrasted with darker body color, many with black

pronotal fascia or macula bordered by testaceous area. Head: Very finely, sparsely punctate to coarsely punctate, adults of

many species with well developed microreticulation. Interocular fovea and interocular tuberculi (ocelli) absent. Clypeus

transverse, sides convergent anteriorly. Labrum bilobed, without apparent sexual dimorphism. Maxillary palpus elongate,

palpomere 2 generally as long as 3 and 4 combined. Mentum generally very slightly longer than wide, finely

microreticulate or punctulate. Genae smooth or with a posterior ridge. Antennae of nine articles (4 + 5). Thorax:

Pronotum with sides slightly to moderately produced at middle, denticulate; anterior angles produced in one species only.

Lateral areas of pronotum with more or less developed anteroexternal foveolae, posteroexternal foveolae in many adults

also. Disc with posterointernal foveolae present or absent; anterior region of many adults with shallow transverse

depression. Sculpture of disc varied from extremely finely sparsely punctate to coarsely punctate and with microreticulate

interstices. Prosternum of most adults with coxae separated by thin carina, of few adults separated from carina by thin

shelf. Mesosternum of most adults with internal and external carinae divergent from anterior to posterior; intercoxal

process of most adults quite narrow, few adults as wide as long; apex varied from blunt to acute, of few adults elevated to

form ridge contiguous with same on metasternum. Metasternum with glabrous plaques present or absent; plaques of

various shapes including elongate, oval, totally carinate, carinate at lateral extremes and arcute. Elytra: Most adults with

10 rows of punctures between suture and humeral callus, few adults with punctures random on disc or on entire elytron.

Intervals varied from flat to subcarinate, in few adults with alternate intervals elevated. Explanate margin very narrow to

broad. Elytral apices, in posterior aspect, in most adults turned upward in form of angle with one another; in few adults,

angles not formed. Abdomen: Intercoxal segment flat or concave. First four sterna and anterior region of 5 with hydrofuge

pubescence. Posterior region of sterna 5 very sparsely pubescent in males, with relatively long setae in females. Sternum 6

sparsely pubescent. Apical sternum (actual tenth) retracted in some adults. Legs: Protarsi without obvious expanded pads

of suction setae. Protibiae of many adults enlarged or excavate near apex. Mesotarsi with symmetrical claws except for

adults of one species. Mesotibiae straight in most, arcuate in few adults. Metatibiae varied from slender to markedly

enlarged, adults of some species with brush of hairs, prominent spines, or tubercles. Genitalia: Aedeagus varied markedly,

paramere insertion varied from at base to near apex. Paramere shape varied from slender to lobate, males of few species

with one paramere bifid. Right paramere of most males larger than left, but not in form of cup into which remainder of

aedeagus rests. Central portion of aedeagus varied from slender to nearly oval. Apex of few males with flagellum.

Quaest. Ent., 1980, 16 (1,2)

64

Perkins

Key to the groups of Western Hemisphere Hydraena

1 (0) Posterior ridge of genae well developed (Fig. 21H); intercoxal segment of

abdomen concave, with posterior margin markedly arcuate (Fig. 2 ID); scintilla

absent 2

T Posterior ridge of genae absent (Figs. 48E,54D,57A,63G) or nearly

imperceptible; intercoxal segment flat, with posterior margin straight or weakly

arcuate (Figs. 48D,57B,63A,B); scintilla present or absent 3

2 ( 1 ) Pronotum widest near midlength (Fig. 2 1C); elytral punctures serial or, in few

adults, with few random punctures on disc (Figs. 21A,G); prosternal carina not

produced anteriorly into a short spine, or very weakly so (Fig. 2 IE); species

from Canada and the United States circulata Group, p. 72

2' Pronotum widest before midlength; elytral punctures entirely random on disc;

prosternal carina produced anteriorly into a short spine; one species from

Surinam paeminosa Group, p. 210

3 ( 1') Pronotum with posterointernal foveolae; scintilla present or absent

(Figs. 31C,32B,48C) leechi Group, p. 102

y Pronotum without posterointernal foveolae (Figs. 54A,C); scintilla absent ....

marginicollis Group, p. 164

Key to circulata Group species of Western Hemisphere Hydraena

1 ( 0 ) Meso- and metatibiae arcuate H. quadricurvipes, new species p.

V Meso- and metatibae not arcuate

2 ( 1 ) Elytral disc with some random punctures

2' ( 1 ) Elytral disc with punctures in series

3 (2) Plaques arcuate, separated by twice plaque width; Appalachian Mountains . . .

H. appalachicola , new species, p.

y Plaques straight, separated by plaque width; Lake County, California

H. mignymixys, new species, p.

4 ( 2') Species from eastern United States and adjacent Canada (including angulicollis

Notman, see distribution map, (Fig. 25A)

4' Species from western United States and adjacent Canada

5 ( 4 ) Pronotum with dark brown macula on disc, not extended into lateral depressed

areas; aedeagus as illustrated (Fig. 26B) H. atlantica, new species, p.

5' Pronotum dark brown except for narrow brownish or testaceous border;

aedeagus otherwise

6 ( 5') Elytral intervals not elevated; plaques separated anteriorly by more than plaque

width; pronotal punctation more widely separated; average size smaller;

aedeagus as illustrated (Fig. 24D) H. angulicollis Notman, p.

6' Elytral intervals slightly elevated; plaques separated anteriorly by plaque width;

pronotal punctation more closely spaced; average size larger; aedeagus

otherwise

7 ( 60 Plaques separated posteriorly by plaque width; aedeagus as illustrated

(Fig. 29B) H. ancylis, new species, p.

1' Plaques separated posteriorly by less than plaque width; aedeagus as illustrated

(Fig. 29A) H. pennsylvanica Kiesenwetter, p.

93

2

3

4

83

92

5

8

85

6

82

7

99

96

Western Hemisphere Hydraenidae

65

8 ( 40 Plaques elevated, carinate at posterior in most specimens, separated at posterior

by about four times plaque width or more; black; aedeagus as illustrated

(Fig. 29D) H. nigra Hatch, p.

8' Plaques not elevated, separated by twice plaque width, or less;

black or brownish

9 ( 8') Body form broad, 1.78 mm x 0.88 mm; legs short, stout; palpi relatively short;

aedeagus as illustrated (Fig. 28 A); Yosemite Falls, California

H. yosemitensis, new species, p.

9' Characters not as above

10 (90 Metasternum with distinctive long and dense pubescence lateral to each plaque;

pronotum smaller, more incised at rear; Pacific coast states

10' Metasternum without unusual long and dense pubescence lateral to plaques,

pronotum larger, less incised at rear

11 (10 ) Aedeagus as illustrated (Fig. 29C) H. vandykei d’Orchymont, p.

1 1' Aedeagus as illustrated (Figs. 30A,B) H. sierra , new species, p.

12 (100 Legs and lateral borders of pronotum ochraceus; aedeagus as illustrated

(Fig. 28C) H. californica, new species , p.

12' Legs and lateral borders of pronotum brown or black

13 (120 Aedeagus with setae of parameres short, sparse

13' Aedeagus with setae of parameres long, dense

14 (13 ) Aedeagus as illustrated (Figs. 26A,C,D) H. pacifica , new species, p.

14' Aedeagus as illustrated (Fig. 28D) H. petila, new species, p.

15 (130 Aedeagus with parameres broad in lateral view

15' Aedeagus with parameres slender in lateral view

16 (15 ) Aedeagus as illustrated (Fig. 22A) H. tuolumne, new species, p.

16' Aedeagus as illustrated (Fig. 22B) H. occidentalism new species, p.

17 (150 Aedeagus as illustrated (Fig. 22C) H. arenicola, new species p.

17' Aedeagus as illustrated (Fig. 22D) H. circulata, new species, p.

Key to leechi Group species of Western Hemisphere Hydraena

1 ( 0 ) Pronotal scintilla present (Figs. 31C,32B,40D)

V Pronotal scintilla absent

2 ( 1 ) Male metatibial brush present (Figs. 32D-G)

2' Male metatibial brush absent; female specimens

3 ( 2 ) Plaques oval or absent

3' Plaques carinate

4 (3) Tubercle lateral to each plaque (Figs. 31H,35B); aedeagus as illustrated

(Fig. 33D); southern Arizona H. bituberculata , new species, p.

4' Tubercle absent

5 ( 40 Size larger, about 1.92 - 2.02 mm long; protibia excavate near apex; profemoral

prominence cariniform; aedeagus as illustrated (Figs. 36B,D); Oaxaca and

Hidalgo, Mexico H. scintilla , new species, p.

5" Size smaller, about 1.85 mm long or less; protibia not excavate near apex;

profemoral prominence tuberculate

6 ( 50 Size larger, about 1.80 x 0.76 mm; aedeagus as illustrated (Fig. 33A); Arizona,

84

9

94

10

11

12

100

101

88

13

14

15

86

91

16

17

79

78

75

74

2

30

3

9

4

7

109

5

111

6

Quaest. Ent., 1980, 16 (1,2)

66

Perkins

New Mexico, Texas, northern Mexico H. leechi, new species, p. 103

6' Size smaller, about 1.76 x 0.76 mm; aedeagus as illustrated (Fig. 36A); Jalisco,

Mexico H. scopula, new species, p. 115

7 ( 3') Plaques truncate posteriorly; aedeagus as illustrated (Fig. 36C); Zacatecas,

Mexico H. canticacollis, new species, p. 113

7/ Plaques not truncate posteriorly 8

8 ( 7 ) Plaques arcuate; protibia parallel sided; aedeagus as illustrated (Fig. 33B);

Durango, Mexico H. breedlovei, new species, p. 106

8' Plaques straight; protibia expanded; aedeagus as illustrated (Fig. 33C);

southern Arizona H. arizonica , new species, p. 108

9 ( 2 ') Tubercle lateral to each plaque; southern Arizona; females of

H. bituberculata, new species, p. 109

9' Tubercle absent 10

10 (9') Elytral punctures on disc random 11

10' Elytral punctures on disc in series 12

11 (10 ) Form narrow, length about 2.92 times width; longer, about 1.46 mm; aedeagus

as illustrated (Fig. 4 1C); Appalachian Mountains of Virginia

H. maureenae, new species, p. 138

11' Form wider, length about 2.02 - 2.30 times width; shorter, about 1.38 mm;

aedeagus as illustrated (Figs. 41A,B); Ozark Plateau of Missouri, Oklahoma,

Tennessee, Indiana H. ozarlcensis, new species, p. 136

12 (10') Procoxae separated from median carina by narrow shelf; Paraguay

H. paraguay ensis Janssens, p. 128

12' Procoxae not separated from median carina by narrow shelf 13

13 (12') Elytron with alternate intervals elevated; aedeagus as illustrated (Fig. 37 A);

Durango, Mexico H. alternata, new species, p. 116

13' Elytron with alternate intervals not elevated 14

14 (13') Elytral margin, viewed posteriorly, not elevated obliquely toward suture, not in

form of angle with opposite elytron; Guatemala .... H. puncticollis Sharp, p. 130

14' Elytral margin, viewed posteriorly, elevated obliquely toward suture, in form of

angle with opposite elytron (Fig. 54E) 15

15 (14') Profemur with carina on inner surface near base 16

1 5' Profemur without carina on inner surface near base 18

16 (15 ) Pronotum shiny, finely sparsely punctate, punctures separated by two to three

times puncture diameter; plaques absent; aedeagus as illustrated (Fig. 38B);

Colombia H. scintillabella, new species, p. 118

16' Pronotum dull, coarsely densely punctate, punctures separated by less than

puncture diameter; plaques present 17

17 (16') Pronotum unicolorous dark brown, lateral depressed areas microreticulate;

aedeagus as illustrated (Fig. 39A); Peru H. pavicula, new species, p. 123

17' Pronotum with dark brown, rectangular macula on disc, remainder testaceous,

lateral depressed areas not microreticulate; aedeagus as illustrated (Fig. 38A);

highlands of southeastern Brazil H. scintillutea , new species, p. 119

18 (15') Plaques various shapes other than small ovals at posterior 0.20 of metasternum

19

18' Plaques absent or reduced to small ovals at posterior 0.20 of metasternum ... 23

Western Hemisphere Hydraenidae 67

19 (18 ) Plaques arcuate 20

19' Plaqes straight 21

20 (19) Plaques separated posteriorly by four times plaque width; aedeagus as

illustrated (Fig. 39D); Colombia H. colombiana, new species, p. 127

20' Plaques separated posteriorly by twice plaque width; Brazil

H. plaumanni d’Orchymont, p. 129

21 (19') Plaques subtriangular, each plaque tapered from posterior to anterior 22

2 1' Plaques oval or subrectangular; aedeagus as illustrated (Fig. 37B); Chiapas,

Mexico H. campbelli, new species, p. 132

22 (21 ) Pronotal punctures on disc separated by less than puncture diameter; aedeagus

as illustrated (Fig. 39B); Argentina H. costiniceps, new species, p. 124

22' Pronotal punctures on disc separated by one to two times puncture diameter;

Bolivia H. germaini d’Orchymont, p. 126

23 (180 Plaques absent 24

23' Plaques reduced to small ovals at posterior 0.20 of metasternum 25

24 (23 ) Pronotal and elytral pubescence apparent; Durango, Mexico; females of

H. breedlovei , new species, p. 106

24' Pronotal and elytral pubescence obsolete; aedeagus as illustrated (Fig. 38C);

highlands of southeastern Brazil H. alterra, new species, p. 121

25 (230 Head with occipital area slightly emarginate in midline to receive scintilla . 27

25' Head lacking emargination in midline of occipital area to receive scintilla;

Arizona; females of H. arizonica, new species, p. 108

26 (25 ) Protibia stout, enlarged in apical 0.66; Oaxaca and Hidalgo, Mexico; females of

H. scintilla , new species, p. Ill

26' Protibia not stout, gradually enlarged from base to apex 27

27 (26') Pronotal punctation finer, sparser; Guatemala H. sordida Sharp, p. 129

27' Pronotal punctation coarser, denser, 28

28 (27 ) Size smaller, 1.36 mm or less; aedeagus as illustrated (Fig. 38D); highlands of

southeastern Brazil H. terralta, new species p. 122

28' Size larger, 1.68 mm or more; Arizona, Mexico 29

29 (28') Pronotal lateral margins more arcuate; size larger, about 1.88 mm; Arizona,

New Mexico, Texas, northern Mexico; females of H. leechi, new species p. 103

29' Pronotal lateral margins less arcuate; size smaller, about 1.68 mm; Jalisco,

Mexico; females of H. scopula, new species, p. 115

30 (1') Elytral punctures on disc random 31

30' Elytral punctures on disc serial 32

31 (30 ) Pronotal disc shiny, punctures separated by two to four times puncture

diameter; interstices smooth; aedeagus as illustrated (Fig. 39C); Mexico

H. zapatina, new species, p. 131

31' Pronotal disc dull; interstices rough; aedeagus as illustrated (Fig. 45B);

primarily coastal, Maryland to Florida H. youngi, new species, p. 1 50

32 (30') Pronotal reliefs dull, microreticulate; aedeagus as illustrated (Fig. 44A);

Chiapas, Mexico and Guatemala H. oblio, new species, p. 149

32' Pronotal reliefs shiny, non-microreticulate or extremely faintly so 33

33 (32') Metasternum with an anterior, median ridge (Fig. 48D) 34

33' Metasternum lacking an anterior, median ridge 42

Quaest. Ent., 1980, 16 (1,2)

68

Perkins

34 (33 ) Pronotum with anterior angles produced (Fig. 48C); broad, flat body: aedeagus

as illustrated (Fig. 45 A); Mexico, Nayarit to Oaxaca

H. cuspidicollis , new species, p. 162

34' Anterior angles of pronotum not produced 35

35 (34") Mesosternal intercoxal process narrow, width about 0.25 distance between

internal and median carinae; Durango, Mexico 36

35' Mesosternal intercoxal process broad, width subequal to distance between

internal and median carinae 37

36 (35 ) Pronotum with posterointernal foveolae more deeply impressed; elytra less

rounded at sides; aedeagus as illustrated (Fig. 47D)

H. bractoides, new species, p. 161

36' Pronotum with posteroexternal foveolae less deeply impressed; elytra more

rounded at sides; aedeagus as illustrated (Fig. 47C)

H. bractea, new species, p. 160

37 (35') Plaques separated by more than twice plaque width 38

31' Plaques separated by less than twice plaque width 39

38 (37 ) Plaques elevated; depression between plaques well developed; pronotal discal

punctures separated by two to three times puncture diameter; aedeagus as

illustrated (Fig. 47 A); Durango and Jalisco, Mexico

H. prieto, new species, p. 157

38" Plaques not elevated; depression between plaques slightly developed; pronotal

discal punctures separated by puncture diameter; aedeagus as illustrated

(Fig. 46A); Jalisco, Mexico H. crystallina, new species, p. 155

39 (370 Plaques separated by plaque width or less; aedeagus as illustrated (Fig. 46C);

Mexico, Mexico H. scolops, new species, p. 153

39' Plaques separated by more than plaque width 40

40 (390 Plaques elevated at lateral margins, relative to remainder of plaque; aedeagus as

illustrated (Fig. 47B); Durango, Mexico H. argutipes, new species, p. 158

40' Plaques not elevated at lateral margins, relative to remainder of plaque 41

41 (400 Metasternal ridge well developed, acute in cross-section; pronotal discal

punctures separated by puncture diameter; size larger, about 1.70 x 0.72 mm;

aedeagus as illustrated (Fig. 46D); Oaxaca, Mexico

H. oaxaca, new species, p. 152

41' Metasternal ridge weakly developed, rounded in cross-section; pronotal discal

punctures separated by twice puncture diameter; size smaller, about 1.36 x

0.60 mm; aedeagus as illustrated (Fig. 46B); Jalisco, Mexico

. ... H. mazamitla, new species, p. 1 56

42 (330 Plaques reduced to small ovals at posterior 0.17 of metasternum; aedeagus as

illustrated (Fig. 4 ID); Tamaulipas, Mexico H.exilipes, new species, p. 133

42' Plaques various, not reduced to small ovals at posterior 0.17 of metasternum . 43

43 (420 Plaques convergent anteriorly 44

43' Plaques parallel 47

44 (43 ) Plaques separated at anterior by about four times greatest width of plaque;

aedeagus as illustrated (Fig. 44B); northeastern United States

H. punctata LeConte, p. 148

44' Plaques separated at anterior by about twice greatest width of plaque 45

Western Hemisphere Hydraenidae

69

45 (44') Elytral intervals about 0.25 puncture diameter in width; size larger, about 1.57

x 0.68 mm; Brazil H. sahlbergi d’Orchymont, p.

45' Elytral intervals about puncture diameter in width; size smaller, about 1.30 x

0.58 mm

46 (450 Elytral margins, viewed posteriorly, turned slightly upward toward suture; body

form slightly broader; aedeagus as illustrated (Fig. 44C); primarily coastal,

eastern United States, Maryland to Texas H. spangleri, new species, p.

46' Elytral margins, viewed posteriorly, not turned upward toward suture; body

form slightly narrower; aedeagus as illustrated (Fig. 44D); Guadeloupe,

Jamaica, Costa Rica H. guadelupensis d’Orchymont p.

47 (43') Pronotal lateral margins not convergent from middle to anterior angles;

posterointernal foveolae very slightly developed; aedeagus as illustrated

(Fig. 64A); Venezuela, Guyana and Brazil H. hyalina, new species, p.

47' Pronotal lateral margins convergent from middle to anterior angles;

posteroexternal foveolae generally more apparent

48 (47') Pronotal posterointernal foveolae very lightly impressed or absent; form broad,

about 1.18 x 0.52 mm; pronotum finely, moderately densely punctate; aedeagus

as illustrated (Fig. 43C); Cuba H. decui Spangler, p.

48' Pronotal posterointernal foveolae well developed; pronotum more coarsely and

densely punctate

49 (48') Size smaller, about 1.16 mm long; aedeagus as illustrated (Fig. 43D); Brazil

H. orcula, new species, p.

49' Size larger, about 1.40 mm long; aedeagus as illustrated (Figs. 43A,B);

Honduras to Trinidad via mainland H. particeps, new species, p.

Key to marginicollis Group species of Western Hemisphere Hydraena

1 ( 0 ) Prosternal carina separated from procoxae by a narrow shelf; mesosternal

intercoxal process broad, width slightly greater than distance separating internal

and median carinae (Figs. 63 A, F ){geminya Subgroup)

1' Prosternal carina not separated from procoxae by a narrow shelf; mesosternal

intercoxal process narrow, width less than distance separating internal and

median carinae (Figs. 54B,I,63B) ( marginicollis Subgroup)

2 ( 1 ) Pronotal fascia occupying median 0.33; plaques very narrow, separated

posteriorly by eight times plaque width; aedeagus as illustrated (Fig. 64B);

Nayarit, Mexico H. vela , new species, p.

2' Pronotal fascia occupying median 0.50; plaques separated posteriorly by less

than three times plaque width

3 ( 2') Plaques less convergent anteriorly, nearly parallel, separated at anterior by

more than plaque length; aedeagus as illustrated (Fig. 64C); Chiapas, Mexico

H. chiapa , new species, p.

3' Plaques more convergent anteriorly, separated at anterior by less than plaque

length; aedeagus as illustrated (Fig. 64D); Oaxaca, Mexico

H. geminya, new species, p.

4 (1') Pronotum entirely testaceous or with testaceous borders and very faint light

brown macula on disc

141

46

146

145

179

48

144

49

140

142

2

4

206

3

207

209

5

Quaest. Ent., 1980, 16 (1,2)

70

Perkins

4'

5 (4)

5'

6 (5')

6'

7 (40

7

8 (7)

8'

9 (70

9'

10 (9)

10'

11 (10)

11'

12 (100

12'

13 (12)

13'

14 (130

14'

15 (120

15'

16 (150

Pronotal disc dark brown or black, usually with anterior and posterior margins

light brown or testaceous 7

Elytra with fine, close-set punctures in series; metasternum shallowly depressed

between plaques; aedeagus as illustrated (Fig. 43C); Cuba . . . H. decui Spangler, p.

144

Elytra with fine, sparse punctures which do not form definite rows;

metasternum deeply impressed between plaques; Panama 6

Metasternal plaques located at border of inverted, V-shaped depression; elytra

entirely brown; aedeagus as illustrated (Fig. 49C)

H. limpidicollis, new species, p. 167

Metasternal plaques located at border of inverted, U-shaped depression; elytra

brown with faint ochraceous macula on disc; aedeagus as illustrated (Fig. 49D)

H. newtoni, new species, p. 168

Elytra with at least some punctures on disc random, not forming discrete rows

8

Elytra with discal punctures in rows 9

Elytra of males greatly truncate, posterior margin of each elytron sinuate;

plaques not carinae at lateral margins; aedeagus as illustrated (Fig. 52B);

Trinidad, Guyana H. premordica, new species, p. 175

Elytra not truncate, posterior margin of each elytron not sinuate; plaques

carinate at lateral margins; aedeagus as illustrated (Fig. 58B); Colombia

H. anisonycha , new species, p. 191

Plaques absent or reduced to small ovals at posterior 0.20 or metasternum ... 10

Plaques various, not reduced to small ovals at posterior 0.20 of metasternum 17

Plaques absent 11

Plaques small ovals 12

Elytral intervals and punctures equal in width; size smaller, about

1.48 x 0.60 mm; aedeagus as illustrated (Fig. 55A); eastern United States,

primarily coastal, from New Jersey to Louisiana

H. marginicollis Kiesenwetter, p. 184

Elytral intervals 0.50 puncture width; size larger, about 1.56 x 0.56 mm;

aedeagus as illustrated (Fig. 55C); eastern North America from Texas to

southern Mexico H. pulsatrix, new species, p. 187

Size about 1.40 - 1.45 mm 13

Size about 1.26 - 1.35 mm 15

Aedeagus as illustrated (Fig. 49 A); Argentina

H. tucumanica, new species, p. 165

Aedeagus not as above; Central America 14

Aedeagus as illustrated (Fig. 55D); southern Mexico and Guatemala

H. longicollis Sharp, p. 190

Aedeagus as illustrated (Fig. 55B); Costa Rica

H. turrialba, new species, p. 186

Elytral intervals and punctures equal in width; aedeagus as illustrated

(Fig. 51 A); Guatemala H. guatemala, new species, p. 169

Elytral intervals about 0.50 puncture diameter 16

Aedeagus as illustrated (Fig. 58 A); Peru H. peru, new species, p. 190

Western Hemisphere Hydraenidae

71

16' Aedeagus as illustrated (Fig. 60B); Costa Rica

H. nevermanni, new species, p. 195

17 (9') Plaques elevated at anterior or along entire length 18

17' Plaques not elevated 20

18 (17 ) Plaques carinate along entire length; pronotal discal punctures separated by

three to six times puncture diameter; very shiny species; aedeagus as illustrated

(Fig. 52A); Mexico H. grouvellei d’Orchymont, p. 174

18' Plaques elevated at anterior; pronotal discal punctures separated by one to three

times puncture diameter 19

19 (180 Metatibiae of males greatly expanded (Figs. 61A,B); metatibiae of females

widest at midlength; aedeagus as illustrated (Fig. 62B); Chiapas, Mexico ....

H. d-destina , new species, p. 200

19' Metatibiae of both sexes gradually enlarging from base to apex; aedeagus as

illustrated (Fig. 52D); Matto Grosso, Brazil

H. anaphora , new species, p. 178

20 (170 Metatibiae of males expanded; metatibiae of females widest at midlength;

aedeagus as illustrated (Fig. 62C); Chiapas, Mexico

H. barricula, new species, p. 202

20' Metatibiae of both sexes gradually enlarged from base to apex 21

21 (200 Plaques separated posteriorly by greatest width of a plaque; aedeagus as

illustrated (Fig. 5 IB); Haiti H. haitensis, new species, p. 171

21' Plaques separated posteriorly by more than greatest width of a plaque 22

22 (2T) Plaques triangular 23

22' Plaques oval or elongate 24

23 (22 ) Size larger, about 1.54 x 0.68 mm; aedeagus as illustrated (Fig. 53D);

Guadeloupe H. insularis d’Orchymont, p. 183

23' Size smaller, about 1.48 x 0.64 mm; aedeagus as illustrated (Fig. 5 ID); Cuba .

H. per kinsi Spangler, p. 172

24 (220 Aedeagus with parameres originating below midlength of main-piece 25

24' Aedeagus with parameres originating above midlength of main-piece 30

25 (24 ) Aedeagus with left paramere as long as main-piece (Fig. 64A); Venezuela,

Guyana and Brazil H. hyalina, new species, p. 179

25' Aedeagus with left paramere shorter than main-piece 26

26 (250 Aedeagus with left paramere originating at same distance from base as right

paramere 27

26' Aedeagus with left paramere originating above insertion of right paramere . . 28

27 (26 ) Aedeagus with right paramere extended to apex of main-piece (Fig. 49B);

Ecuador H. quechua, new species, p. 166

27 ' Aedeagus with right paramere not extending to apex of main-piece (Fig. 5 1C);

Mexico H. mexicana, new species, p. 171

28 (260 Aedeagus expanded in lateral view (Fig. 53C); Trinidad

H. trinidensis, new species, p. 182

28' Aedeagus not expanded in lateral view 29

29 (280 Aedeagus with terminal-piece shorter than distance separating base of

main-piece and insertion of right paramere (Fig. 52C); Ecuador

H. jivaro, new species, p. 176

Quaest. Ent., 1980, 16 (1,2)

72

Perkins

29' Aedeagus with terminal-piece longer than distance separating base of

main-piece and insertion of right paramere (Figs. 53A,B); Brazil and Venezuela

H. browni, new species, p.

30 (24') Aedeagus without a slender apical process (Fig. 62D); Chiapas, Mexico

H. splecoma, new species, p.

30' Aedeagus with a slender apical process

31 (300 Aedeagus with left paramere longer than right

3 V Aedeagus with right paramere longer than left

32 (31 ) Size larger, about 1.60 x 0.68 mm; aedeagus as illustrated (Fig. 60A); Central

America H. colymba, new species, p.

32' Size smaller, about 1.30 x 0.52 mm; aedeagus as illustrated (Fig. 62A);

southern Mexico and Guatemala H. sabella, new species, p.

33 (3F) Size larger, about 1.44 x 0.60 mm; aedeagus as illustrated (Fig. 60C); Costa

Rica H. malkini, new species, p.

33' Size smaller, about 1.14 x 0.48 mm; aedeagus as illustrated (Fig. 60D); Panama

H. pontequula, new species, p.

180

204

31

32

33

193

199

196

198

The circulata Group

Members of the circulata Group are characterized by form of the ventral surface of the

head, which has the posterior margin of the genae in the form of a transverse ridge (Fig. 21 H).

Additionally, adults have the intercoxal segment of the abdomen (Fig. 2 ID) concave, with the

posterior margin arcuate. These characteristics are in contrast to those of the leechi and

marginicollis Groups whose adults lack the genal ridge and have a flat intercoxal segment (cf.

Figs. 48 D,E).

The aedeagus, which corroborates the proposed monophyly of circulata Group species, is

very simple compared to that of males in the leechi and marginicollis Groups. The parameres

originate at base of the median piece and are generally slender and with the apex enlarged very

slightly, although they are flattened in males of a few species. The main-piece is tubular for

most of its length, flattened at apex. Interspecific variation generally involves shape of the apex,

in males of a few species also shape of the main-piece, and density and length of the setae on

the parameres(cf. Figs. 22A, 24A, 28A).

Externally this group is quite uniform, requiring referral to the male genitalia for positive

species assignment of adults. Those of most species have well developed plaques and relatively

coarse, microreticulate pronotum and head. Adults of a number of species show a tendency

toward subcarinate elytral intervals. Adults of only a single species, H. quadricurvipes , has

modified legs, the legs of the other species being straight and lacking the various expansions,

excavations, or processes seen in the leechi and marginicollis Groups.

Geographically, the circulata Group is entirely Nearctic, with the greatest concentration of

species in the mountains of the Pacific coast states of the United States. A few species have a

circular distribution pattern around the Great Basin, with the circular pattern interrupted by

the barrier imposed by the arid regions of southeastern California and southwestern Arizona

(see for example Hydraena circulata , Fig. 23 A).

I have arranged the circulata Group in four complexes: circulata , angulicollis, atlantica

and pennsylvanica. These complexes are based upon similarity of aedeagal structure, discussed

Western Hemisphere Hydraenidae

73

Figs. 21 A - H, Hydraena circulata. (A) dorsal habitus. (B) ventral habitus. (C) pronotum (AEF = anteroextemal

foveola, M = margin, PEF = posteroexternal foveola, P1F = posterointernal foveola). (D) metasternum (arrows indicate

metacoxal sensillum and intercoxal sternite). (E) prosternum. (F) protibia. (G) elytra, posterior aspect. (H) head, ventral

aspect (arrow indicates genal ridge).

Quaest. Ent., 1980, 16(1,2)

74

Perkins

in the phylogeny section.

The circulata Complex

1 . Hydraena circulata new species

(Figs. 101,21 A-H,22D,E,23A,148C,164A)

Type-locality. - Little Chico creek at School road, E. of Forest Ranch, 2300 feet, Butte

County, California.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. Hugh B. Leech collected these specimens September 1, 1961. Paratypes (790) are

listed in the appendix.

Diagnosis. - Only males can be reliably assigned to Hydraena circulata , on the basis of

genitalic features.

Description. — Form : Elongate. Size: Holotype 1.80 mm long, 0.72 mm wide. Color. Dorsal surface dark brown.

Maxillary palpi brown; antennae testaceous. Ventral surface dark brown except legs, elytral epipleura and inflexed margin

of pronotum, brown. Head : Length 0.24 mm. Width 0.44 mm. Frons punctation coarse, punctures separated by 0.50

puncture diameter, or less; microreticulation both in punctures and on interstices; surface dull. Frontoclypeal suture

arcuate to rear. Clypeus microreticulate except at anterior margin. Labroclypeal suture straight across middle when

viewed from above. Labrum bilobed, microreticulate, each lobe asymmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2,3 and 4, respectively:

0.26/0.12/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral and medial surfaces arcuate, widest slightly past midlength. Mentum wider than long,

surface moderately shining, microreticulate. Submentum microreticulation similar to mentum. Genae moderately dull,

finely microreticulate, lateral area of each gena with well developed foveola; posterior ridge well developed. Postgena

microreticulation slightly smaller than that of submentum. Last five antennomeres pubescent. Eyes 0.20 interocular

distance in width. Thorax: Pronotum length at midline 0.36 mm; maximum width (at approximately midlength) 0.52 mm;

sides margined, denticulate; sides moderately produced at middle, slightly sinuate and slightly convergent to anterior

angle, sinuate and convergent to posterior; anterior border 0.44 mm wide, straight and nearly perpendicular to midline in

lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.48 mm wide, slightly arcuate to rear.

Posterointernal foveolae moderately developed; punctures in foveola closer together than those on disc. Antero- and

posteroexternal foveolae confluent, sides of pronotum explanate. Transverse foveola moderately developed, punctures

closer together than punctures on disc. Disc dull, punctation coarse, punctures deeply impressed, separated by 0.50

puncture diameter; microreticulation both in larger punctures and on interstices; most punctures with seta extended above

cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina not produced anteriorly as very short spine; coxae

separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina not extended to base of intercoxal process; intercoxal process relatively

narrow, sides tapered, apex subacute, width near apex 0.33 distance between internal and median carinae. Metasternum

with low ridge posterior to intercoxal process; plaques well developed, straight, convergent moderately from posterior to

anterior; plaques 0.50 length of metasternum in midline; width of each plaque slightly less than width of intercoxal process

at its mid-length; plaques separated posteriorly by approximately twice plaque width; plaques separated anteriorly by

plaque width; plaques flat in cross section. Elytra : Length 1.20 mm. Maximum width (at midlength) 0.72 mm. Surface

moderately shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures

rectangular; intervals elevated, width approximately equal to 0.33 puncture width, also interstices between adjacent

punctures of a row; each puncture with seta. Explanate margin moderately developed, ended near apices, with extremely

fine, well separated serrations along entire margin; serrations larger near anterior angles. Elytral apices, in dorsal aspect,

gradually rounded; in posterior aspect, elytral margin elevated very slightly obliquely toward suture, in form of slight angle

with opposite elytron. Abdomen. Intercoxal segment concave. Glabrous segments at apex only moderately produced.

Sternum 7 very slightly emarginate at apex. Legs: Without apparent modification. Genitalia : Aedeagus as illustrated

(Figs. 22D,E). (353 examined).

Variation. - Throughout most of its extensive range, adults of this species have the pronotal

punctation coarse, the punctures separated by thin walls. In Arizona specimens, however, the

pronotum is much smoother and more reflective, the punctures separated by about 0.50 the

Western Hemisphere Hydraenidae

75

diameter of a puncture. Many of these Arizona specimens are light brown, although some are

dark brown or black. Specimens from parts of the range other than Arizona are generally dark

brown or black. The parameres of specimens from Arizona and Colorado (Fig, 22E) are blunt

at the apex and have the setae denser and distributed further down the paramere. From the

external and genitalic details, apparently gene exchange rate between the Arizona and southern

California populations (Fig. 23A) is very low, due to the barrier imposed by the southwestern

deserts.

Natural History. - Most records cite “stream”, “creek” or “river” as part of the locality

description. More unusual habitat descriptors include “pool in drying up stream”, “foul pool,

dried bed of creek” “puddle in grassy slope”, “ephemeral stream”, “pond”, “Ranunculus pool”,

“seepage trickle over gravelly soil”, “seepage over rocks and small cliffs”, “clear water pools in

gravel and stones of otherwise dry and shaded creek”, “ex seepage full of dead conifer leaves”,

“along lake shore”, and “bog”. Elsewhere (Perkins, 1976) I discussed the microhabitat

preferences and associates of Hydraena circulata in southern California ( Hydraena circulata

and H. vandykei are discussed in that paper under the designation “ Hydraena sp.”). My

research revealed that Hydraena circulata is primarily a psammolotic species. The descriptors

cited above probably represent those microhabitats which are secondary, being used at times of

overpopulation, or those microhabitats that the beetles are forced into as streams become dry.

Distribution. - (Figs. 23A,162A). Hydraena circulata is the most widespread and one of the

most common western species of the circulata Group. Distribution forms a circular pattern,

from southern California and northern Baja California northward to British Columbia, then

southward in the Rocky Mountains to southern Arizona.

Etymology. - Latin, circulata (forming a circle). The name refers to the geographical

distribution pattern.

2. Hydraena arenicola new species

(Figs. 22C,27D,164A)

Type-locality. - 6.9 miles N. Middletown, on highway 29, Lake County, California.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. Hugh B. Leech collected these specimens February 20, 1955. Paratypes (433) are

listed in the appendix.

Diagnosis. - The aedeagus must be studied to reliably recognize males of H. arenicola.

Description. — Form: Elongate. Size: Holotype 1 .76 mm long, 0.72 mm wide. Color: Dorsal surface dark brown.

Maxillary palpi and antennae brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of

pronotum, brown. Head: Length 0.24 mm. Width 0.42 mm. Frons punctation coarse, punctures separated by 0.50

puncture diameter, or less; microreticulation present both in punctures and interstices; surface dull. Frontoclypeal suture

arcuate to rear. Clypeus microreticulate except at anterior margin. Labroclypeal suture straight across middle in dorsal

aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at approximately

midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.26/0.10/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral and medial surfaces arcuate, widest near midlength. Mentum wider than long, surface

moderately shining, microreticulate. Submentum microreticulate. Genae moderately shining, punctulate; lateral area of

each gena with well developed foveola; posterior ridge well developed. Postgena with microreticulation slightly larger than

that of submentum. Last five antennomeres pubescent. Eyes 0.20 interocular distance in width. Thorax: Pronotum length

at midline 0.36 mm; maximum width (at approximately midlength) 0.52 mm; sides margined, denticulate; sides

moderately produced at middle, slightly sinuate and slightly convergent to anterior angle, sinuate and convergent to

posterior; anterior border 0.42 mm wide, straight and nearly perpendicular to midline in lateral 0.25 moderately arcuate to

rear in middle 0.50; posterior border 0.44 mm wide, slightly arcuate to rear. Posterointernal foveolae well developed;

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Perkins

Figs. 22A - E, Aedeagi of Hydraena holotypes. (A) H. tuolumne. (B) H. oecidentalis. (C) H. arenicola. (D) H. circulata.

(E) parameres of H. circulata (from (top to bottom) Blaine County, Montana; Huerfano County, Colorado; and Cochise

County, Arizona).

Western Hemisphere Hydraenidae

77

Figs. 23 A - F, Geographical distributions of Hydraena species. (A) H. circulata. (B) H. occidentalis. (C) H. vandykei.

(D) H. calif ornica • and H. yosemitensis ★ . (E) H. tuolumne • and H. mignymixys ★ . (F) H. sierra.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

punctures in foveola closer together than those on disc. Antero- and posteroexternal foveolae confluent, sides of

pronotum explanate. Transverse foveola moderately developed, punctures closer together than punctures on disc. Disc

dull, punctures separated by 0.50 puncture diameter, or less; microreticulation present in large punctures only, absent

from interstices; most punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent.

Prosternum carinate, carina not produced anteriorly as very short spine; coxae separated by thin, median carina; carina

sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior;

median carina not extended to base of intercoxal process; intercoxal process relatively broad, sides tapering, apex

subacute, width near apex 0.50 distance separating internal and median carinae. Metasternum with plaques well

developed, straight, convergent moderately from posterior to anterior; plaques 0.50 length of metasternum in midline;

width of each plaque 0.50 width of intercoxal process at its midlength; plaques separated posteriorly by slightly greater

than plaque width; plaques separated anteriorly by slightly less than plaque width; plaques flat in cross section. Elytra:

Length 1.12 mm Maximum width (at midlength) 0.72 mm. Surface dull, disc with 10 rows of punctures between suture

and humeral callus, rows quite regular; most punctures rectangular; intervals elevated, width approximately equal to

0.50 puncture width, as are interstices between adjacent punctures of a row; each puncture with seta. Explanate margin

moderately developed, ended near apices, with serrations near anterior angles and apices. Elytral apices, in dorsal

aspect, gradually rounded; in posterior aspect elytral margin elevated obliquely toward suture, in form of angle with

opposite elytron. Abdomen: Intercoxal segment concave. Glabrous segments at apex weakly produced. Sternum 7 very

slightly emarginate at apex. Legs: Without apparent modification. Genitalia: Aedeagus as illustrated (Fig. 22C) (195

examined).

Natural History. - The great majority of locality records cite “stream” or “creek” as the

macrohabitat. More unusual notations include “pool in drying up stream”, “foul pool dried bed

of creek”, “ephemeral stream”, “moss-edged rock pools in running stream, open area”, “clear

water pools in gravel and stones of otherwise dry and shaded creek bed”, and “small pool in

drying Darlingtonia bog”.

Distribution. - (Figs. 27D,164A). Northern Oregon south to southern California. Greatest

population density in coastal mountain ranges of northern California.

Etymology. - Latin, arena (sand) plus icola (dweller). This name refers to the psammolotic

habits of this species.

3. Hydraena Occident alis new species

(Figs. 22B, 23B, 164A)

Type-locality. - Bloody Run Creek, 7 miles E. of Route 101 on Longvale-Covelo road, 1 100

feet, Mendocino County, California.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. These specimens were collected by Hugh B. Leech July 18, 1968. Paratypes (221) are

listed in the appendix.

Diagnosis. - Aedeagi must be studied to identify males of this species.

Description. — Form: Elongate. Size: Holotype 2.04 mm long, 0.88 mm wide. Color: Dorsal surface dark brown

except narrow border of pronotum and explanate margin of elytra testaceous. Maxillary palpi testaceous; antennae

testaceous. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head:

Length 0.28 mm Width 0.48 mm. Frons dull, punctation coarse, punctures separated by 0.50 puncture diameter, or less.

Clypeus microreticulate. Labroclypeal suture straight across middle in dorsal aspect. Labrum bilobed, microreticulate,

each lobe symmetrical arc; median emargination ended well above midlength of labrum. Maxillary palpus with following

lengths(mm.) of palpomeres 2, 3 and 4, respectively: 0.32/0.12/0.26; second segment bending outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight in basal

0.33 arcuate in apical 0.66 median surface arcuate; apical segment widest near apical 0.33, Mentum wider than long,

surface moderately shining, finely microreticulate. Submentum microreticulate. Genae weakly shining; lateral area of

each gena with well developed foveola; posterior ridge well developed. Postgena with microreticulation smaller than that of

submentum. Last five antennomeres pubescent. Eyes slightly less than 0.20 interocular distance in width. Thorax:

Pronotum length at midline 0.44 mm; maximum width (at approximately midlength) 0.62 mm; sides margined,

denticulate; sides moderately produced at middle, sinuate and slightly convergent to anterior angle, sinuate and convergent

to posterior; anterior border 0.52 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately

arcuate to rear in middle 0.50; posterior border 0.5 2 mm wide, slightly arcuate to rear. Posterointernal foveolae slightly

developed; punctures in foveola similar to those on disc. Antero- and posteroexternal foveolae confluent, in form of

Western Hemisphere Hydraenidae

79

explanate sides. Transverse foveola slightly developed, with punctures separated by thin walls. Disc dull, punctures

relatively large and deeply impressed, separated by thin walls; most punctures finely microreticulate; most punctures

with distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina not produced

anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to base of

intercoxal process; intercoxal process relatively broad, sides tapered, apex rounded, width near apex 0.66 distance

between internal and median carinae. Metasternum with carina in midline between anterior region of plaques and

intercoxal process; plaques well developed, straight, convergent from posterior to anterior; plaques 0.57 length of

metasternum in midline; width of each plaque 0.66 width of intercoxal process at its midlength; plaques separated

posteriorly by approximately plaque width; plaques separated anteriorly by 0.50 plaque width; plaques flat in cross

section; slightly elevated, oblique ridge lateral to each plaque. Elytra: Length 1.40 mm. Maximum width (at midlength)

0.88 mm. Surface dull, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most

punctures rectangular; intervals well elevated, width approximately 0.50 puncture width, as are interstices between

adjacent punctures of a row; each puncture with seta. Explanate margin well developed, ended near apices, with

serrations near anterior angles and in posterior 0.33. Elytral apices in dorsal aspect gradually rounded; posteriorly,

elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment

concave. Glabrous segments at apex very weakly produced. Segment 7 without emargination at apex. Legs: Without

apparent modification. Genitalia: Aedeagus as illustrated (Fig. 22B) (100 examined).

Natural History. - Stream or creek habitats are mentioned in most locality records.

Unusual habitat notations include “ex moss in bed of dried-up woodland pool”, “margin of

Typha pool”, and “ephemeral pond”.

Distribution. - (Figs. 23B,164A). British Columbia, Washington, Oregon and California.

Etymology. - Latin, occidentalis (of the west). This name refers to the geographical

distribution.

4. Hydraena tuolumne new species

(Figs. 22A, 23E, 164 A)

Type-locality. - Tributary of Niagara Creek, Forest Campground, Tuolumne County,

California.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. Hugh B. Leech collected these specimens September 21, 1963. Paratypes (46) are

listed in the appendix.

Diagnosis. - Male genitalic characteristics are the only totally reliable diagnostic features.

Description. — Form: Elongate. Size: Holotype 1.88 mm long, 0.84 mm wide. Color: Head with dorsal surface and

labrum dark brown; maxillary palpi testaceous except apices brown; antennae testaceous. Pronotum brown except dark

brown macula on disc. Elytra brown. Ventral surface dark brown except legs, elytral epipleurae and inflexed margin of

pronotum, brown. Head: Length 0.24 mm. Width 0.44 mm. Frons dull, punctation coarse, punctures separated by 0.33

puncture diameter, or less; microreticulation both in punctures and on interstices. Frontoclypeal suture straight across

middle in dorsal aspect. Labrum bilobed, microreticulate, each lobe asymmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.32/0.12/0.24; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface nearly straight in basal 0.33 arcuate in apical 0.66 median surface evenly

arcuate; palpomere 4 widest slightly past midlength. Mentum wider than long, surface moderately shining,

microreticulate. Submentum microreticulation similar to mentum. Genae dull, finely microreticulate, lateral area of each

gena with well developed foveola; posterior ridge well developed. Postgena with microreticulation slightly smaller than that

of submentum. Last five antennomeres pubescent. Eyes 0.20 interocular distance in width. Thorax: Pronotum length at

midline 0.44 mm; maximum width (at approximately midlength) 0.58 mm; sides margined, denticulate; sides moderately

produced at middle, slightly sinuate and slightly convergent to anterior angle, sinuate and convergent to posterior; anterior

border 0.46 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle

0.50; posterior border 0.50 mm wide, slightly arcuate to rear. Posterointernal foveolae weakly developed; punctures in

foveola similar to those on disc. Antero- and posteroexternal foveolae confluent. Transversal foveola moderately developed,

many punctures in this area confluent. Disc dull, punctation coarse, punctures deeply impressed, many confluent;

microreticulation quite evident in larger punctures, absent from interstices; most punctures with a distinctive seta which

extends above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina not produced anteriorly as very short

spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and

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Perkins

Figs. 24A - D, Aedeagi of Hydraena species. (A) H. quadricurvipes , holotype. (B) H. quadricurvipes , variant from

Monroe County, Indiana. (C) H. appalachicola, holotype. (D) H. angulicollis , Hamilton County, New York.

Western Hemisphere Hydraenidae

81

external carinae divergent from anterior to posterior; median carina not extended to base of intercoxal process;

intercoxal process relatively narrow, sides tapered, width near apex 0.50 distance between internal and median carinae.

Metasternum with plaques well developed, straight, covergent moderately from posterior to anterior; plaques 0.50 length

of metasternum in midline; greatest width of each plaque subequal to width of intercoxal process at its midlength;

plaques separated posteriorly by slightly less than plaque width; plaques separated anteriorly by 0.50 basal width of

plaque; plaques flat in cross section; each plaque narrowed anteriorly. Elytra: Length 1.30 mm. Maximum width (at

midlength) 0.84 mm. Surface dull, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures rectangular; intervals elevated, width approximately equal to 0.50 puncture width, as are

interstices between adjacent punctures of a row; each puncture with a seta. Explanate margin moderately developed,

ended near apices, with serrations near anterior angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in

posterior aspect elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen:

Intercoxal segment concave. Glabrous segments at apex weakly produced. Segment 7 almost truncate at apex. Legs:

Without apparent modification. Genitalia: Aedeagus as illustrated (Fig. 22A) (26 examined).

Natural History. - Most locality records mention flowing water habitats.

Distribution. - (Figs. 23E,164A). Restricted to the Sierra Nevada Mountains of California.

Etymology. - tuolumne , in reference to the type-locality.

Figs. 25 A - D, Geographical distributions of Hydraena species. (A) H. angulicollis. (B) H. atlantica • and Hr

appalachicola ★ . (C) H. pennsylvanica. (D) H. quadricurvipes • and H. ancylis ★ .

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Perkins

The angulicollis Complex

5. Hydraena angulicollis Notman

(Figs. 24D,25A,164B)

Hydraena angulicollis Notman 1921:146 (holotype female in SI I; type-locality: Westfield, Chautauqua County, New

York).

Diagnosis. - Adults are generally darker, smaller and the pronotal punctures are more

widely separated than in adults of H. pennsylvanica and H. ancylis the other species from

eastern North America with which it can be confused. Additionally, H. angulicollis adults

generally do not have the elytral intervals elevated, whereas adults of the aforementioned

species do, more or less. Specimens with external characteristics approaching those of H.

pennsylvanica and H. ancylis can be reliably discerned only by referral to the aedeagus.

Description. — Form: Elongate oval. Size: Holotype 1 .80 mm long, 0.80 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum dark brown except for narrow

testaceous border. Elytra dark brown. Ventral surface dark brown except legs, elytral epipleura and indexed margin of

pronotum, brown. Head: Length 0.24 mm. Width 0.44 mm. Frons punctation coarse, interstices between punctures thin

walls to 0.50 puncture diameter; microreticulation in punctures only, absent from interstices; interstices shining.

Frontoclypeal suture arcuate. Clypeus microreticulate except at anterior margin. Labroclypeal suture straight across

middle when viewed from above. Labrum bilobed, microreticulate; each lobe an asymmetrical arc; median emargination

ending at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4,

respectively: 0.30/0.10/0/20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not

especially expanded; palpomere 4 with lateral and medial surfaces arcuate, widest near midlength. Mentum wider than

long, surface moderately shining, finely and closely punctulate except middle, impunctulate. Submentum evenly, finely

punctulate, punctures contiguous. Genae dull, finely punctulate; lateral area of each gena with well developed foveola;

posterior ridge well developed. Postgena with punctation smaller than that of submentum. Last five

antennomeres pubescent. Eyes 0.20 interocular distance in width. Thorax: Pronotum length at midline 0.42 mm;

maximum width (at approximately midlength) 0.58 mm; sides margined, denticulate; sides relatively slightly produced at

middle, slightly sinuate and slightly convergent to anterior angle, sinuate and convergent to posterior; anterior border

0.48 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50;

posterior border 0.50 mm wide, slightly arcuate to rear. Posterointernal foveolae slightly developed; punctures in foveola

closer together than those on disc, separated by thin walls. Antero- and posteroexternal foveolae confluent, in form of

explanate sides. Transverse foveola not developed, punctures in this area closer together than punctures on disc, separated

by thin walls. Disc moderately dull, interstices shining, punctures separated by thin walls to puncture diameter,

microreticulation only in punctures, absent from interstices; most punctures with distinctive seta extended above cuticle in

dry specimens. Scintilla absent. Prosternum carinate, carina not produced anteriorly as very short spine; coxae separated

by thin, median carina; carina imperceptible anterior to coxae; carina sinuate line in lateral aspect. Mesosternum with

internal and external carinae parallel; median carina not extended to base of intercoxal process; intercoxal process

relatively narrow, sides tapered; apex subacute, width near apex 0.50 distance between internal and median carinae.

Metasternum with plaques well developed, straight, converging moderately from posterior to anterior; plaques 0.50 length

of metasternum in midline; greatest width of each plaque subequal to width of intercoxal process at its midlength; each

plaque tapered slightly from posterior to anterior; plaques separated posteriorly by approximately plaque width; plaques

separated anteriorly by approximately plaque width; plaques flat in cross section. Elytra: Length 1.24 mm. Maximum

width (at midlength) 0.80 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows

quite regular; most punctures hexagonal; intervals not elevated, width approximately equal to 0.50 puncture width, as are

interstices between adjacent punctures of a row; each puncture with seta. Explanate margin moderately developed, ended

near apices, with serrations near anterior angles and in posterior 0.33. Elytral apices in dorsal aspect gradually rounded; in

posterior aspect elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen:

Intercoxal segment concave. Glabrous segments at apex not produced. Segment 7 not emarginate at apex. Legs: Legs

without apparent modification. Genitalia: Aedeagus as illustrated (Fig. 24D) (98 examined).

Variation. - Density of the pronotal punctures varies considerably. Most specimens have the

punctures more widely separated than that seen in H. pennsylvanica adults. As stated in the

diagnosis, H. angulicollis adults are also generally darker and smaller than those of H.

pennsylvanica. However, I have studied collections from various localities, especially from

Western Hemisphere Hydraenidae

83

Michigan, each of which I judged all of the specimens to be H. pennsylvanica on the basis of

external characteristics. Upon dissection these series were found to be composite. The aedeagi

of males of the two species are highly dissimilar and cannot be confused. I have examined 184

specimens (see appendix).

Natural History. - Locality descriptors include “leaf litter using a Berlese funnel”, “sifting

leaves”, “sphagnum, streamside alder swamp”, “in shore debris”, and “small lake edge”. I have

collected H. angulicollis in Maine, at the margin of a small stream. The microhabitat at that

locality consisted of sand and gravel which was bordered by sphagnum moss. Further study is

necessary to definitely demonstrate an affinity for sphagnum moss, which would be an unusual

habitat preference for a member of the circulata Group, and for the genus in general.

Distribution. - (Figs. 25 A, 164B). H. angulicollis is the only Hydraena with a

trans-Canadian distribution, ranging from Fort Simpson, Northwest Territories in Canada

southeastward to Maryland.

Remarks. - Although the holotype is a female, it is the externally distinctive form (see

variation), and I have no reservations concerning its identity.

6. Hydraena appalachicola new species

(Figs. 24C,25B,164B)

Type-locality. - Two miles S. Mountain Grove, Blowing Springs public camp, Bath County,

Virginia.

Type-specimens. - The holotype male is deposited in USNM. My wife Maureen and I

collected this specimen June 3, 1973. The allotype, which is also deposited in USNM is

labelled: 12 miles S. Williamsville, Bath County, Virginia, M. E. and P. D. Perkins. One male

paratype with same data as the holotype is in PDP. Two male and one female paratypes, also

deposited in my collection, are labelled: 5 miles NE New Paltz, Ulster County, New York, P.

D. Perkins.

Diagnosis. - These attractive specimens are easily distinguished from other members of the

circulata Group by the non-serial arrangement of the punctures on the elytral disc. Only adults

of H. mignymixys , a California species, also have some non-serial elytral punctures, but differ

greatly in body form, color and sculpture. The following features make the pronotum of H.

appalachicola adults very distinctive: (1) the disc has a rectangular, black or dark brown

macula which is surrounded by, and contrasts with, the testaceous borders, (2) the punctures

are rather coarse, but are apparently not microreticulate and are well separated by the very

shiny interpunctal areas, and (3) the sides in the posterior are deeply incised.*

Description. — Form: Elongate oval. Size: Holotype 1.56 mm long, 0.76 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous except for

transverse, rectangular, dark brown macula on disc. Elytra brown. Ventral surface dark brown except legs, elytral

epipleura and inflexed margin of pronotum, testaceous. Head: Length 0.22 mm. Width 0.42 mm. Frons punctation coarse,

punctures separated by 0.50 puncture diameter; microreticulation on interstices and in punctures; surface moderately dull.

Frontoclypeal suture arcuate to rear. Clypeus finely microreticulate. Labroclypeal suture straight across middle in dorsal

aspect. Labrum bilobed, microreticulate; each lobe asymmetrical arc; median emargination ended at approximately

midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2,3 and 4, respectively: 0.24/0.08/0.18;

palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4

with lateral and medial surfaces arcuate, widest near basal 0.33. Mentum wider than long, surface moderately shining,

punctures fine, contiguous except in middle. Submentum evenly, finely punctulate, punctures contiguous. Genae

moderately shining, finely punctulate; area of each gena with a well developed foveola; posterior ridge well developed.

Postgena with punctation similar in size to that of submentum. Last five antennomeres pubescent. Eyes slightly less than

0.25 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately

midlength) 0.56 mm; sides margined, denticulate; sides moderately produced at middle, slightly sinuate and slightly

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84

Perkins

convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.48 mm wide, straight and nearly

perpendicular to midline in lateral 0.25 moderately arcuate to rear in middle 0.50 posterior border 0.44 mm wide,

slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola closer together than those

on disc. Posteroexternal foveola moderately developed. Interfoveolar depression moderately developed. Area between

external foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped,

extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola moderately developed,

punctures closer together than punctures on disc. Disc shining, punctures deeply impressed, separated by thin walls to

0.50 puncture diameter; some punctures with seta extended above cuticle in dry specimens. Scintilla absent. Prosternum

carinate, carina not produced anteriorly as very short spine; coxae separated by thin, median carina; carina a sinuate

line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median

carina not extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered apex subacute,

width near apex 0.50 distance between internal and median carinae. Metasternum with plaques well developed, slightly

arcuate; plaques 0.50 length of metasternum in midline; width of each plaque subequal to width of intercoxal process at

its midlength; plaques separated by approximately twice plaque width; plaques flat in cross section. Elytra: Length

1.08 mm. Maximum width (at midlength) 0.76 mm. Surface shining, disc with 10 rows of punctures between suture

and humeral callus, however, rows somewhat irregular with serial arrangement of punctures ceasing in places; punctures

large, intervals reduced to thin, irregular walls, interstices between adjacent punctures of a row much larger, frequently

equal puncture diameter; most punctures with seta. Explanate margin moderately developed, ended near apices, with

fine serrations in anterior and posterior 0.33. Elytral apices, in dorsal aspect gradually rounded; in posterior aspect

elytral margin not elevated obliquely towards suture, not in form of angle with opposite elytron. Abdomen: Intercoxal

segment concave. Glabrous segments at apex weakly produced. Segment 7 without emargination at apex. Legs: Without

apparent modification. Genitalia: Aedeagus as illustrated (Fig. 24C)(4 examined).

Variation. - No significant variation was noted in the six specimens studied.

Natural History. - The specimens collected at the type-locality were in a sandy area of a

stream outwash in the mountains of Virginia (Fig. 189A). The specimen from Bath County, 12

miles S. Williamsville, was collected at the margin of a small stream, the substratum of which

consisted primarily of small, smooth slate fragments; this specimen was found in association

with a large population of Limnebius, primarily L. ozapalachicus , but also including L.

discolor Casey and L. richmondi, new species (Fig. 193B). The three specimens from Ulster

County, New York, were in a small sandy area at the margin of a very rapid, very cold brook

during winter.

Distribution. - (Figs. 25B,164B). Presently known from the Appalachian Mountains in the

states of Virginia and New York.

Etymology. - appalachian plus icola (dweller). Named in reference to the geographical

distribution.

7. Hydraena nigra Hatch, new status

(Figs. 27F,29D,164B)

Hydraena vandykei niger Hatch, 1965:20 (holotype male in UWA; type-locality: Galena, Blaine County, Idaho).

Diagnosis. - The carinate metasternal plaques serve as diagnostic features for these black,

relatively smooth members of the circulata Group. Refer to the section on variation for further

comments.

Description. — Form: Elongate oval. Size: Holotype 2.00 mm long, 0.76 mm wide. Color: Dorsal surface black.

Maxillary palpi testaceous; antennae testaceous. Ventral surface dark brown except legs, elytral epipleura and inflexed

margin of pronotum, brown. Head: Length 0.24 mm. Width 0.42 mm. Frons punctation moderately coarse, punctures

separated by 0.50 puncture diameter, or greater; microreticulation only in punctures, absent from interstices; interstices

shining. Frontoclypeal suture arcuate to rear. Clypeus microreticulate except at anterior margin. Labroclypeal suture

straight across middle when viewed from above. Labrum bilobed, microreticulate, each lobe symmetrical arc; median

emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively; 0.28/0.10/0.22; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral and medial surfaces slightly arcuate, widest past

midlength. Mentum wider than long, surface moderately shining, microreticulate. Submentum microreticulation similar to

mentum. Genae dull, microreticulate, lateral area of each gena with a well developed foveola; posterior ridge well

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85

developed. Postgena with microreticulation slightly smaller than that of submentum. Last five antennomeres pubescent.

Eyes 0.20 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at

approximately midlength) 0.56 mm; sides margined, denticulate; sides moderately produced at middle, straight and

slightly convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.46 mm wide, straight and

nearly perpendicular to midline in lateral 0.25, moderately arcuate in rear in middle 0.50; posterior border 0.46 mm

wide, slightly arcuate to rear. Posterointernal foveolae well developed; punctures in foveola closer together than those on

disc. Posteroexternal foveola moderately developed. Interfoveolar depression moderately developed. Area between

external foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped,

extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola weakly developed, with

punctures separated by thin walls. Disc moderately shining, punctures microreticulate, generally separated by 0.50

puncture diameter although few in middle confluent; most punctures with distinctive seta extended above cuticle in dry

specimens. Scintilla absent. Prosternum carinate, carina not produced anteriorly into very short spine; coxae separated

by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent

from anterior to posterior; median carina extended to base of intercOxal process; intercoxal process relatively broad,

sides tapered, apex round, width near apex 0.66 distance between internal and median carinae. Metasternum with

plaques well developed, straight, carinate at posterior, convergent moderately from posterior to anterior; plaques 0.50

length of metasternum in midline; greatest width of each plaque 0.25 width of intercoxal process at its midlength;

plaques separated posteriorly by approximately six times plaque width; plaques separated anteriorly by twice plaque

width. Elytra: Length 1.24 mm. Maximum width (at midlength) 0.76 mm. Surface moderately shining, disc with 10

rows of punctures between suture and humeral callus, rows quite regular; most punctures irregularly shaped; intervals

not elevated, surface quite irregular, reflections interrupted, width approximately equal to 0.50 puncture diameter, as

are interstices between adjacent punctures of row; each puncture with seta. Explanate margin moderately developed,

ended near apices, with extremely fine, well separated serrations along entire margin, those near anterior and posterior

larger. Elytral apices, in dorsal aspect, gradually rounded; viewed posteriorly, elytral margin elevates slightly, obliquely

toward suture, in form of slight angle with opposite elytron. Abdomen: Intercoxal segment concave. Glabrous segments

at apex slightly produced. Segment 7 without emargination at apex. Legs: Without apparent modification. Genitalia:

Aedeagus as illustrated (Fig. 29D)(50 examined).

Variation. - Of the 116 specimens studied, only 13 from a single locality in Tuolumne

County, California did not have the metasternal plaques carinate. The plaques of these 13

specimens were, however, narrow and widely separated as is seen in the carinate forms. The

aedeagi from this locality did not differ significantly from those of the remaining specimens

studied.

Natural History. - Most locality descriptors mention “creek”, “stream” or “headwaters”,

although there is one citation each of “bog” and “in moss”. This suggests that this species is

primarily a lotic, psammophilous form. The fact that it has been collected at high elevations, as

much as 9500 feet in Colorado, plus its absence from the coastal ranges of California, Oregon

and Washington causes me to suspect that perhaps H. nigra is a cold adapted species.

Distribution. - (Figs. 27F,164B). Found in the Sierra Nevada Mountains of California

south to the San Gabriel Mountains and north to southern Oregon, and in the Rocky

Mountains from southern British Columbia south to New Mexico.

The atlantica Complex

8. Hydraena atlantica new species

(Figs. 25B,26B,150D,153A-C,165A)

Type-locality. - Plummers Island, Montgomery County, Maryland.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. Paul J. Spangler collected these specimens May 19, 1972. Paratypes (199) are

listed in the appendix.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Diagnosis. - Adults are readily distinguished from those of other members of the circulata

Group found in eastern North America by the dark brown pronotal macula which does not

extend into the lateral explanate areas. The aedeagus (Fig. 26B) must be studied to identify

teneral specimens.

Description. — Form: Elongate oval Size: Holotype 1.86 mm long, 0.80 mm wide. Color: Head with dorsal surface

very dark brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum with dark brown macula

on disc, not extended into lateral explanate areas; remainder of pronotum testaceous-orange. Elytra brown. Ventral surface

dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.24 mm. Width

0.44 mm. Frons punctation coarse, microreticulate, interstices between punctures 0.50 puncture diameter; interstices

shining. Frontoclypeal suture weakly arcuate to rear. Clypeus microreticulate. Labroclypeal suture straight when viewed

from above. Labrum bilobed, microreticulate, each lobe asymmetrical arc; median emargination ending above midlength

of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively; 0.32/0.12/0.24;

palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4

with lateral and medial surfaces slightly arcuate, widest near midlength. Mentum wider than long, surface moderately

shining, finely punctulate. Submentum finely punctulate. Genae moderately shining with transverse impressions, lateral

area of each gena with well developed foveola, posterior ridge well developed. Postgena with punctation slightly larger than

that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.20 interocular distance in width. Thorax:

Pronotum length at midline 0.44 mm; maximum width (at approximately midlength) 0.58 mm; sides margined,

denticulate; sides moderately produced at middle, slightly sinuate and very slightly convergent to anterior angle, markedly

sinuate and markedly convergent to posterior; anterior border 0.50 mm wide, straight and nearly perpendicular to midline

in lateral 0.12, moderately arcuate to rear in middle 0.50, posterior border 0.48 mm wide, rather markedly arcuate to rear.

Posterointernal foveolae extremely slightly developed; punctures in foveola similar to those on disc. Antero- and

posteroexternal foveolae confluent, sides explanate and disc elevated, parallel-sided. Transverse foveola not developed,

punctures in this area somewhat closer together than punctures on disc. Disc relatively dull, but with interstices shining,

punctures large and deeply impressed, separated by narrow walls; most punctures with distinctive seta extended above

cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina not produced anteriorly as very short spine; coxae

separated by a thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina not extended to base of intercoxal process; intercoxal process relatively

narrow, sides tapered apex round, width near apex 0.33 distance between internal and median carinae. Metasternum with

plaques well developed, straight, convergent moderately from posterior to anterior; plaques 0.50 length of metasternum in

midline; width of each plaque subequal to width of intercoxal process at its midlength; plaques separated posteriorly by

approximately plaque width; plaques separated anteriorly by slightly less than plaque width; plaques flat in cross section;

shallow furrow lateral to each plaque. Elytra: Length 1.24 mm. Maximum width (at midlength) 0.80 mm. Surface

shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures longer than

wide; intervals very slightly elevated, width approximately equal to 0.50 puncture diameter, as are interstices between

adjacent punctures of row; each puncture with seta. Explanate margin moderately developed, ended near apices, with well

develpped serrations near anterior angles and extremely fine, well separated serrations along remainder of margin. Elytral

apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin not elevated obliquely toward suture, not in

form of angle with opposite elytron. Abdomen: Intercoxal segment concave. Glabrous segments at apex very slightly

produced. Segment 7 without emargination at apex. Legs: Without apparent modification. Genitalia: Aedeagus as

illustrated (Fig. 26B)(106 examined).

Natural History. - Habitat descriptors include “woodland pond”, “pothole”, and “pasture

pool”, indicating that H. atlantica may be primarily a lentic adapted species. Most collections,

however, do not indicate habitat and the few mentioned above may or may not represent those

macrohabitats where H. atlantica reaches its greatest reproductive potential. A detailed study

of the natural history of this species is necessary to firmly establish its preferred habitat and

limiting environmental factors.

Distribution. - (Figs. 25B,165A). Eastern North America from Maine south to Virginia.

Etymology. - Latin, atlantica , in reference to geographical distribution and presumed

relationship to H. pacifica as indicated by aedeagal form.

9. Hydraena pacifica , new species

(Figs.26A,C-D,27A-C,165A)

Western Hemisphere Hydraenidae

87

Type-locality. - Tributary to Vance Creek, Trinity Valley, British Columbia, Canada.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. Hugh B. Leech collected these specimens October 3, 1946. Paratypes (634) are listed

in the appendix.

Diagnosis. - Aedeagal form is the only feature which can be consistently relied upon to

discriminate males of this species.

Description. — Form: Elongate-oval. Size: Holotype 1.96 mm long, 0.84 mm wide. Color: Head with dorsal surface

black; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum black except extremely narrow,

testaceous border at anterior and posterior. Elytra very dark brown, virtually black. Ventral surface dark brown except

legs, elytral epipleura and inflexed margin of pronotum, brown. Head: Length 0.26 mm. Width 0.6 mm. Frons moderately

coarsely punctate, surface moderately dull. Frontoclypeal suture arcuate to rear. Clypeus microreticulate at sides, shining

in midline. Labroclypeal suture straight when viewed from above. Labrum bilobed, microreticulate, each lobe symmetrical

arc; median emargination ended above midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.32/0.12/0.22; palpomere 2 bent outward at approximately midlength; apex of

palpomere 2 more expanded than norm; palpomere 4 with lateral surface slightly angulate, median surface evenly arcuate;

palpomere 4 widest slightly past midlength. Mentum wider than long, surface shining, finely microreticulate. Submentum

with punctation similar to mentum. Genae shining; lateral area of each gena with well developed foveola; posterior ridge

well developed. Postgena with punctation much smaller than that of submentum. Last five antennomeres pubescent. Eyes

0.20 interocular distance in width. Thorax: Pronotum length at midline 0.44 mm; maximum width (at approximately

midlength) 0.62 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate and convergent to

anterior angle, sinuate and convergent to posterior; anterior border 0.48 mm wide, straight and nearly perpendicular to

midline in lateral 0.25, moderately arcuate to rear in middle 0.50 posterior border 0.52 mm wide, slightly arcuate to rear.

Posterointernal foveolae moderately developed; punctures in foveola closer together than those on disc. Posteroexternal

foveola well developed. Interfoveolar depression well developed. Area between external foveolae moderately elevated.

Anteroexternal foveolae well developed, each foveola slightly crescent shaped, occupying slightly less than 0.33 width of

anterior region of pronotum. Transverse foveola moderately developed, punctures separated by thin walls. Disc shining,

punctures moderate sized, deeply impressed, separated by thin walls near anterior and posterior borders, by puncture

diameter in middle; most punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent.

Prosternum very weakly carinate, carina not produced anteriorly as very short spine; coxae separated by thin, median

carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae parallel; median carina not

extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered, apex acute, width near apex 0.25

distance between internal and median carinae. Metasternum with plaques well developed, straight, convergent moderately

from posterior to anterior; plaques 0.57 length of metasternum in midline; width of each plaque subequal to width of

intercoxal process at its midlength; plaques separated posteriorly by approximately plaque width; plaques separated

anteriorly by 0.50 plaque width; plaques flat in cross section. Elytra: Length 1.32 mm. Maximum width (at midlength)

0.84 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most

punctures rectangular; intervals elevated, width slightly less than 0.50 puncture diameter, interstices between adjacent

punctures of row generally narrower; each puncture with seta. Explanate margin moderately developed, ended near

posterior 0.10, with fine serrations near anterior angles and apices. Elytral apices in dorsal aspect gradually rounded; in

posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen:

Intercoxal segment concave. Glabrous segments at apex very slightly produced. Segment 7 without emargination at apex.

Legs: Without apparent modification. Genitalia: Aedeagus as illustrated (Figs. 26A, C-D)(393 examined).

Variation. - Color varies from brown to black. There is also some variation in density of

pronotal punctation, but no distinct geographical trends were noted. I have studied the

aedeagus of more than 390 males and have found that there are three rather distinct forms,

which I refer to as aedeagal morphs “A”, “B” and “C” (Figs. 26A, C-D). Aedeagal morph

“A”, which is the morph of the holotype, has a very wide distribution (Fig. 27A) ranging from

Los Angeles County, California northward through the Pacific coast states to British

Columbia, then southward in the Rocky Mountains to Colorado, with a few localities in

Nevada connecting the California and Rocky Mountain components. Aedeagal morph “B” is

known only from the Pacific coast states and British Columbia, apparently absent from the

Rocky Mountains in the United States (Fig. 27B). Aedeagal morph “C” (Fig. 27C) has a very

restricted distribution, being found only in the inland mountains of northern California. I have

seen a total of 89 males of the “B” morph and 26 males of the “C” morph. The localities of

these latter two morphs are entered in the appendix, separately from the “A” morph localities

Quaest. Ent., 1980, 16 (1,2)

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Perkins

(which are designated paratypes). I am not totally convinced that one and not two or possibly

three species are truly represented here. However, the genitalia are quite similar and could very

well represent three stages in a morphocline. I have therefore decided to treat them as forms of

a single species and hope that pointing out these differences will stimulate additional research

into this problem. A total of 848 specimens of this species were studied (see appendix).

Natural History. - The vast majority of locality descriptors include the terms “stream” or

“creek”, indicating that H. pacifica is primarily a lotic species. Unusual citations include

“pools in drying streambed”, “streambed by sifting”, “ex waterlogged limb in stream”, “bog”,

“pools, small stream in Darlingtonia bog”, and “moss”.

Distribution. - (Figs. 27A-C). Western North America.

Etymology. - Latin pacifica , in reference to geographical distribution.

10. Hydraena calif ornica new species

(Figs. 23D, 28C, 165A)

Type-locality. - Mill Valley, Marin County, California.

Type-specimens. - The holotype male is deposited in CAS. This specimen was collected by

Hugh B. Leech, April 25, 1957. The allotype, which is also deposited in CAS, was collected at

Redwood Park, Humboldt County, California by J. O. Martin in 1918. Paratypes (14) are

listed in the appendix.

Diagnosis. - Aedeagal form plus ochraceous legs and lateral areas of the pronotum serve as

diagnostic features for H. californica .

Description. — Form: Elongate-oval. Size: Holotype 1.76 mm long, 0.78 mm wide. Color: Head with dorsal surface

brown; labrum brown; maxillary palpi testaceous; antennae testaceous. Pronotum with explanate sides ochraceous,

remainder brown. Elytra brown except testaceous explanate margin. Ventral surface brown except legs, elytral epipleura

and inflexed margin of pronotum, ochraceous. Head: Length 0.24 mm. Width 0.42 mm. Frons punctation lightly

impressed, punctures separated by 0.50 puncture diameter; microreticulation both in punctures and on interstices, very

lightly impressed on latter; surface dull. Frontoclypeal suture arcuate to rear. Clypeus microreticulate. Labroclypeal

suture straight across middle when viewed from above. Labrum bilobed, microreticulate, each lobe asymmetrical arc;

median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.30/0.1 0/0. 22;palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not expecially expanded; palpomere 4 with lateral surface weakly arcuate, median surface more

markedly arcuate, palpomere 4 widest near midlength. Mentum wider than long, surface moderately shining,

microreticulate. Submentum microreticulate as mentum. Genae shining, microreticulate, lateral area of each gena with

well developed foveola; posterior ridge well developed. Postgena microreticulate. Last five antennomeres pubescent. Eyes

0.17 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately

midlength) 0.58 mm; sides margined, denticulate; sides moderately produced at middle, slightly sinuate and slightly

convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.46 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.48 mm wide, slightly

arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola closer together than those on disc.

Antero- and posteroexternal foveolae confluent, sides of pronotum explanate. Area between external foveolae slightly

elevated. Transverse foveola slightly developed, punctures separated by thin walls. Disc dull, punctures moderately small,

separated by thin walls; most punctures without distinctive seta extended above cuticle in dry specimens. Scintilla absent.

Prosternum carinate, carina not produced anteriorly as very short spine; coxae separated by thin, median carina; carina

sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median

carina extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered, apex subacute, width near

apex 0.33 distance between internal and median carinae. Metasternum with plaques well developed, straight, convergent

moderately from posterior to anterior; plaques 0.50 length of metasternum in midline; width of each plaque subequal to

width of intercoxal process at its midlength; plaques separated posteriorly by approximately twice plaque width; plaques

separated anteriorly by plaque width; plaques flat in cross section. Elytra: Length 1.16 mm. Maximum width (at

midlength) 0.78 mm. Surface moderately shining, disc with 10 rows of punctures between suture and humeral callus, rows

and puncture shape quite irregular; intervals not elevated, reduced to narrow, irregular walls, as are interstices between

adjacent punctures of row; each puncture with seta. Explanate margin well developed, ended near apices, with extremely

fine, well separated serrations along entire margin. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect,

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89

elytral margin elevated slightly obliquely toward suture, in form of slight angle with opposite elytron. Abdomen:

Intercoxal segment concave. Glabrous segments at apex slightly produced. Segment 7 slightly emarginate at apex.

Legs: Without apparent modification. Genitalia: Aedeagus as illustrated (Fig. 28C)(12 examined).

Figs. 26A - D, Aedeagi of Hydraena species. (A) H. pacifica, holotype. (B) H. atlantica , holotype. (C) H. pacifica, morph

“B”, Marin County, California. (D) H. pacifica , morph “C”, Shasta County, California.

Natural History. - Two locality citations include the term “creek”, the remaining citations

give no information about habitat.

Distribution. - (Figs. 23D, 165A). Restricted to the coastal ranges of northern California

from Humboldt County south to Santa Cruz County.

Etymology. - H. californica , in reference to the geographical distribution.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Figs. 27A - F, Geographical distributions of Hydraena species. (A) H. pacifica, morph “A”. (B) H. pacifica , morph “B”.

(C) H. pacifica , morph “C”. (D) H. arenicola. (E) H. petila. (F) H. nigra.

Western Hemisphere Hydraenidae

91

11. Hydraena petila new species

(Figs. 27E,28D,165A)

Type-locality. - Dead Mule spring, 3 km by road N. of Paskenta-Covelo road, 1570 meters,

Tehama County, California.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. Hugh B. Leech collected these specimens August 29, 1972. Paratypes (96) are listed in

the appendix.

Diagnosis. - Aedeagal form is the only totally reliable diagnostic feature for males of this

species.

Description. — Form: Elongate-oval. Size: Holotype 1.90 mm long, 0.80 mm wide. Color: Dorsal surface black.

Maxillary palpi testaceous; antennae testaceous. Ventral surface dark brown except legs, elytral epipleura and inflexed

margin of pronotum, brown. Head: Length 0.24 mm. Width 0.46 mm. Frons punctation coarse, punctures separated by

0.33 puncture diameter or less, microreticulation present both in punctures and on interstices; surface dull. Frontoclypeal

suture arcuate to rear. Clypeus microreticulate except at anterior border. Labroclypeal suture straight across middle when

viewed from above. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.32/0.12/0.22; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not expecially

expanded; palpomere 4 with lateral and medial surfaces arcuate; widest slightly past midlength. Mentum wider than long,

surface moderately shining, microreticulate. Submentum microreticulation similar to mentum. Genae dull,

microreticulate, lateral area of each gena with well developed foveola; posterior ridge well developed. Postgena with

punctation slightly smaller than that of submentum. Last five antennomeres pubescent. Eyes 0.20 interocular distance in

width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately midlength) 0.60 mm; sides

margined, denticulate; sides moderately produced at middle, slightly sinuate and slightly convergent to anterior angle,

sinuate and convergent to posterior; anterior border 0.48 mm wide, straight and nearly perpendicular to midline in lateral

0.25, moderately arcuate to rear in middle 0.50; posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal

foveolae well developed; punctures in foveola closer together than those on disc. Anteroexternal and posteroexternal

foveolae confluent; sides of pronotum explanate. Transverse foveola moderately developed, punctures separated by thin

walls. Disc dull, punctures separated by 0.33 puncture diameter to thin walls; microreticulation in punctures, absent from

interstices; each puncture with distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum

carinate, carina not produced anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in

lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina not

extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered, apex subacute, width near apex

0.33 distance between internal and median carinae. Metasternum with low ridge posterior to intercoxal process; plaques

well developed, straight, convergent moderately from posterior to anterior; plaques 0.57 length of metasternum in midline;

width of each plaque 0.66 width of intercoxal process at its midlength; plaques separated posteriorly by approximately

twice plaque width; plaques separated anteriorly by plaque width; plaques flat in cross section. Elytra: Length 1.28 mm.

Maximum width (at midlength) 0.80 mm. Surface dull, disc with 10 rows of punctures between suture and humeral callus,

rows quite regular; most punctures rectangular; intervals elevated, width approximately equal to 0.50 puncture diameter,

as are interstices between adjacent punctures of row; each puncture with seta. Explanate margin moderately developed,

ended near apices, with serrations along entire margin, those near anterior angles and apices larger than remainder.

Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in

form of angle with opposite elytron. Abdomen: Intercoxal segment concave. Glabrous segments at apex weakly produced.

Segment 7 without emargination at apex. Legs: Without apparent modification. Genitalia: Aedeagus as illustrated

(Fig. 28D)(52 examined).

Natural History. - Nearly all of the locality records indicate “creek” or “stream”. Unusual

habitat descriptions include “moss-edged rock pools in running stream, open area”, and “clean

water pools in gravel and stones of otherwise dry and shaded creek bed”.

Distribution. - (Figs. 27E,165A). Coastal mountain ranges of central and northern

California plus one locality at Vancouver, British Columbia.

Etymology. - Latin, petila (slender). This name refers to the slender aedeagus.

Quaest. Ent., 1980, 16 (1,2)

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12. Hydraena mignymixys new species

(Figs. 23E,28B,165A)

Type-locality. - Dried bed of Cottage City creek, Lucerne, Lake County, California.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. Paratypes (11) from the same locality are deposited in CAS, USNM and PDP. Hugh

B. Leech collected these specimens July 30, 1955.

Diagnosis. - Small, narrow body (1.56 x 0.60 mm) and non-serial arrangement of punctures

on the elytral disc serve to distinguish adults of this species from other members of the circulata

Group in western North America. H. appalachicola adults from eastern North America also

have some non-serial elytral punctures on the disc but differ in body form, color and sculpture.

Description. — Form: Elongate. Size: Holotype 1.56 mm long, 0.60 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous except for dark brown

macula on disc. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum,

brown. Head: Length 0.20 mm. Width 0.38 mm. Frons punctation coarse, punctures confluent; microreticulation

prominent within punctures; surface dull. Frontoclypeal suture slightly arcuate to rear. Clypeus microreticulate except at

anterior border, very smooth. Labroclypeal suture straight across middle in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:0.26/0. 10/0.20; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight in basal 0.33, arcuate in apical 0.66, median surface arcuate; palpomere 4 widest near midlength. Mentum wider

than long, surface moderately shining, microreticulate. Submentum with punctation similar to mentum. Genae dull,

microreticulate, lateral area of each gena with well developed foveola; posterior ridge well developed. Postgena with

microreticulation smaller than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.17

interocular distance in width. Thorax: Pronotum length at midline 0.34 mm; maximum width (at approximately

midlength) 0.44 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate and slightly

convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.38 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.38 mm wide, slightly

arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola confluent. Posteroexternal foveola

weakly developed, lnterfoveolar depression slightly developed. Area between external foveolae moderately elevated.

Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33

width of anterior region of pronotum. Transverse foveola weakly developed. Disc dull, punctures confluent; interstices in

form of irregular patterns; microreticulation quite evident within punctures, but absent from interstices; most large

punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina not

produced anteriorly as very short spine; coxae separated by thin, median carina sinuate line in lateral aspect. Mesosternum

with internal and external carinae divergent from anterior to posterior; median carina not extended to base of intercoxal

process; intercoxal process relatively narrow, sides tapered, apex round, width near apex 0.33 distance between internal

and median carinae. Metasternum with plaques well developed, straight, parallel; plaques 0.50 length of metasternum in

midline; width of each plaque subequal to width of intercoxal process at its midlength; plaques separated by plaque width;

plaques sloped slightly toward midline, each plaque very slightly concave. Elytra: Length 0.98 mm. Maximum width (at

midlength) 0.60 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus at extreme

anterior and in posterior 0.50, punctures in middle more deeply impressed and random; intervals in posterior 0.50 slightly

elevated, width approximately equal to 0.33 puncture width, interstices between adjacent punctures of row generally

narrower; each puncture with perceptible seta. Explanate margin quite narrow, ended near apices, with serration near

anterior angles and in apical 0.25. Elytral apices, in dorsal aspect, gradually rounded; viewed posteriorly, elytral margin

rises very slightly, obliquely towards suture, in form of very slight angle with opposite elytron. Abdomen: Intercoxal

segment concave. Glabrous segments at apex weakly produced. Segment 7 without emargination at apex. Legs: Without

apparent modification. Genitalia: Aedeagus as illustrated (Fig. 28B)(6 examined).

Distribution. - (Figs. 23E,165A). Known only from the type-locality at Lucerne, Lake

County, California.

Etymology. - Greek, mignymi (mix up, mingle) plus ixys (the small of the back). This

name refers to the non-serial arrangement of some punctures on the elytral disc.

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13. Hydraena quadricurvipes new species

(Figs. 24A-B,25D,165A)

Type-locality. - 2 miles NE Subligna, outside Parker Cave, Chattooga County, Georgia.

Type-specimens. - The holotype male is deposited in CFMNH. This specimen was collected

by S. Peck and A. Fiske June 20, 1967. The allotype, which is also deposited in CFMNH, has

the following data; Alabama, St. Claire Co., 3 miles NE Whitney Junction, outside McGlendon

Cave, June 15, 1967, S. Peck and A. Fiske collectors. Paratypes (7) are listed in the appendix.

Diagnosis. - Adults of this distinctive species are easily recognized by form of the meso- and

metatibiae, which are very markedly arcuate in males and weakly arcuate in females. All other

species in the circulata Group have straight meso- and metatibiae. Both sexes have the elytra

broadly explanate and relative length of the ultimate segment of the maxillary palpus is greater

than that seen in other species, more than twice the length of the penultimate article. H.

quadricurvipes includes the most robust members of the circulata group.

Description. — Form: Moderately ovate, convex. Size: Holotype 1 .90 mm long, 0.90 mm wide. Color: Head with

dorsal surface dark brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum brown except

dark brown macula on disc. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of

pronotum, brown. Head: Length 0.26 mm. Width 0.46 mm. Frons punctation coarse, microreticulate; interstices between

punctures 0.33 puncture diameter or less; microreticulation quite evident in larger punctures, present, but lightly

impressed on interstices; surface dull. Frontoclypeal suture slightly arcuate to rear. Clypeus microreticulate. Labroclypeal

suture straight across middle when viewed from above. Labrum bilobed, microreticulate; each lobe asymmetrical arc;

median emargination ending slightly before midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.26/0.10/0.24; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface slightly arcuate; median surface sinuate;

palpomere 4 widest slightly before midlength. Mentum wider than long, surface moderately dull, microreticulate.

Submentum with microreticulation similar to mentum. Genae dull, with large, irregular punctures; lateral area of each

gena with well developed foveola;posterior ridge well developed. Postgena with microreticulation similar to that of

submentum. Last five antennomeres pubescent. Eyes 0.16 interocular distance in width. Thorax: Pronotum length ai

midline 0.44 mm; maximum width (at approximately midlength) 0.64 mm;sides margined, denticulate; sides moderately

produced at middle, slightly sinuate and very slightly convergent to anterior angle, sinuate and convergent to posterior;

anterior border 0.54 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in

middle 0.50; posterior border 0.54 mm wide, slightly arcuate to rear. Posterointernal foveolae absent. Posteroexternal

foveolae well developed. Interfoveolar depression well developed, disc elevated. Area between external foveolae moderately

elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less

than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area somewhat closer

together than punctures on disc. Disc dull, punctures large and deeply impressed, separated by 0.33 puncture diameter or

less; microreticulation well impressed in large punctures, very lightly impressed on interstices; most punctures without

distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina not produced

anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum

with internal and external carinae divergent from anterior to posterior; median carina not extended to base of intercoxal

process; intercoxal process relatively narrow, sides tapered, apex acute, width near apex 0.25 distance separating internal

and median carinae. Metasternum with low ridge in midline between anterior region of plaques and intercoxal process;

plaques well developed, medial margins convergent, lateral margins parallel, therefore each plaque wider at anterior than

posterior; plaques 0.50 length of metasternum in midline; greatest width of each plaque 0.33 again larger than width of

intercoxal process at its midlength; plaques separated posteriorly by approximately twice plaque width; plaques separated

anteriorly by less than 0.50 plaque width; plaques flat in cross setion. Elytra: Length 1.28 mm. Maximum width (at

midlength) 0.90 mm. Surface moderately dull, disc with 10 rows of punctures between suture and humeral callus, rows

quite regular; most punctures rectangular; intervals not elevated, width approximately equal to 0.50 puncture width, as are

interstices between adjacent punctures of a row; most punctures without perceptible seta. Explanate margin quite broad,

ended near apices, with serrations along entire margin, those near anterior angles well developed. Elytral apices, in dorsal

aspect, gradually rounded; viewed posteriorly, elytral margin not elevated obliquely toward suture, not in form of angle

with opposite elytron. Abdomen: Intercoxal segment concave. Glabrous segments at apex weakly produced. Segment 7

without apical emargination. Legs: Meso- and metatibiae markedly arcuate; apical 0.33 of each expanded. Genitalia:

Aedeagus as illustrated (Figs. 24A-B)(4 examined).

Variation. - As noted in the diagnosis, the meso- and metatibiae of females are very slightly

arcuate, whereas those of males are markedly so. Males from Indiana have the aedeagus

Quaest. Ent., 1980, 16 (1,2)

94

Perkins

slightly different than that seen in the holotype and other southern specimens. I have illustrated

the aedeagus of a specimen from Monroe County, Indiana for comparative purposes

(Fig. 24B). No significant, non-sexual external variation was noted in the nine specimens

studied.

Natural History. - The specimens from Alabama and Georgia were taken at or near the

entrance to caves. The specimen from Marshall County, Alabama has the label notations,

“River Cave” and “floor debris light zone at entrance”. The holotype and one male paratype

from Chattooga County, Georgia are from “outside Parker Cave” while the paratype from St.

Claire County in the same state has the label reading, “outside McGlendon Cave”. The latter

three specimens were taken in berlese samples. One of the examples from Indiana was taken

from a “small stream near Needmore”, according to the label notation of F. N. Young. Label

data of the remaining specimens do not describe habitat. Whether H. quadricurvipes truly has

an affinity for cave entrance habitats, and whether the unusual legs of this species are causually

related to that habitat are questions which require further study to clarify.

Distribution. - (Figs. 25D,165A). Presently known from the states of Indiana, Maryland,

Alabama and Georgia.

Etymology. - Latin, quadri (four) plus curv (bend) plus ipes (foot). Named in reference to

the arcuate meso- and metatibiae.

14. Hydraena yosemitensis new species

(Figs. 23D,28A,165A)

Type-locality. - Yosemite Falls, Mariposa County, California.

Type-specimen. - The holotype male (unique) is deposited in CAS. This specimen was

collected by F. Vaillant, August 28, 1962.

Diagnosis. - Broad body form (1.78 x 0.88 mm) with very transverse pronotum, plus the

short, stout legs and relatively short palpi serve to distinguish adults of H. yosemitensis from

those of other species of the circulata Group.

Description. — Form: Broad. Size: Holotype 1.78 mm long, 0.88 mm wide. Color: Dorsal surface dark brown,

nearly black. Maxillary palpi and antennae brown. Ventral surface dark brown except legs, elytral epipleura and inflexed

margin of pronotum, brown. Head: Length 0.24 mm. Width 0.48 mm. Frons punctation coarse, interstices between

punctures 0.50 puncture diameter of less; microreticulation present in punctures only, absent from interstices; surface dull.

Frontoclypeal suture arcuate to rear. Clypeus microreticulate. Labroclypeal suture straight across middle when viewed

from above. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at approximately

midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.22/0.08/0.14; palpomere 2 bent outward at approximately midlength; apex of palpomere 2 relatively broad; palpomere 4

broad, lateral surface slightly arcuate, medial surface more strongly arcuate, widest near midlength. Mentum wider than

long, surface dull, microreticulate. Submentum microreticulate. Genae dull, microreticulate, lateral area of each gena with

a well developed foveola; posterior ridge well developed. Postgena microreticulate. Last five antennomeres pubescent. Eyes

slightly less than 0.20 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at

approximately midlength) 0.62 mm; sides margined, denticulate; sides moderately produced at middle, straight and

slightly convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.52 mm wide, straight and

nearly perpendicular to midline in lateral 0.33, slightly arcuate to rear in middle 0.33 posterior border 0.54 mm wide,

slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola closer together than those on

disc. Posteroexternal foveola strongly developed. Interfoveolar depression weakly developed. Area between external

foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat cresent shaped, extended

across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola moderately developed, punctures

somewhat closer together than punctures on disc. Disc dull, punctures separated by 0.50 puncture diameter,

microreticulation only in punctures, absent from interstices; each puncture with distinctive seta extended above cuticle in

dry specimens. Scintilla absent, prosternum carinate, carina not produced anteriorly as very short spine; coxae separated

by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae parallel;

median carina not extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered; apex

Western Hemisphere Hydraenidae

95

petila.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

subacute, width near apex 0.33 distance between internal and median carinae. Metasternum with low ridge posterior to

intercoxal process; plaques well developed, straight, convergent moderately from posterior to anterior; plaques 0.50

length of metasternum in midline; width of each plaque subequal to width of intercoxal process at its midlength; plaques

separated posteriorly by approximately plaque width; plaques separated anteriorly by 0.50 plaque width; plaques flat in

cross section. Elytra: Length 1.20 mm; maximum width (at midlength) 0.88 mm. Surface dull, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures irregular in shape, intervals not

elevated, width approximately equal to puncture diameter, as are interstices between adjacent punctures of row; each

puncture with seta. Explanate margin moderately developed, ended near apices, with serrations near anterior angles.

Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin not elevated obliquely toward

suture, not in form of angle with opposite elytron. Abdomen: Intercoxal segment concave. Glabrous segments at apex

weakly produced. Segment 7 without emargination at apex. Legs: Legs relatively short and stout. Genitalia: Aedeagus

as illustrated (Fig. 28A)(1 examined).

Distribution . - (Figs. 23D,165A). Known only from the type-locality at Yosemite Falls,

Yosemite National Park, Mariposa County, California.

Etymology. - Latin yosemitensis, in reference to the geographical distribution.

The pennsylvanica Complex

15. Hydraena pennsylvanica Kiesen wetter

(Figs. 25C,29A,165B)

Hydraena pennsylvanica Kiesenwetter 1849:166 (Neotype male deposited in USNM, here designated; type-locality:

Bryant Road, Emmet County, Michigan). - d’Orchymont, 1923:41.

Despite inquiries at various European museums, I was unable to find the holotype of this

species, and believe that it has been destroyed. To insure taxonomic stability a neotype is herein

designated.

Diagnosis. - This species is most easily confused with H. ancylis and H. angulicollis, two

species with which it is sympatric in the eastern United States. Specimens of H. pennsylvanica

can be distinguished from those of H. ancylis by aedeagal form and the more widely separated

metasternal plaques of the latter. Most specimens of H. pennsylvanica can be distinguished

from most specimens of H. angulicollis by the latter’s dark color, smoother pronotum, smaller

Western Hemisphere Hydraenidae

97

size and non-elevated elytral intervals. However, as discussed in the diagnosis and variation

sections of H. angulicollis, certain specimens can be distinguished only by referral to aedeagal

characteristics.

Description. — Form: Elongate oval. Size: Neotype 1.80 mm long, 0.80 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum dark brown except narrow

testaceous border at anterior and posterior. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and

inflexed margin of pronotum, brown. Head: Length 0.24 mm. Width 0.40 mm. Frons punctation coarse, interstices equal

to 0.50 puncture diameter; interstices shining. Frontoclypeal suture slightly arcuate to rear. Clypeus finely punctulate.

Labroclypeal suture straight when viewed from above. Labrum bilobed; surface punctulate; each lobe symmetrical arc;

median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.28/0.12/0.20; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral and medial surfaces weakly arcuate, widest near

midlength. Mentum wider than long, surface slightly shining, finely punctulate. Submentum evenly, finely punctulate,

punctures contiguous. Genae weakly shining, with several large pits; lateral area of each gena with well developed foveola;

posterior ridge well developed. Postgena with punctation similar to that of submentum. Last five antennomeres pubescent.

Eyes 0.20 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately

midlength) 0.56 mm; sides margined, denticulate; sides moderately produced at middle, slightly sinuate and slightly

convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.46 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.56 mm wide, slightly

arcuate to rear. Posterointernal foveolae very slightly developed; punctures in foveola closer together than those on disc.

Posteroexternalfoveola moderately developed. Area between external foveolae nearly flat. Anteroexternal foveolae well

developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of

pronotum. Transverse foveola weakly developed. Disc relatively dull, but with interstices shining, punctures large and

deeply impressed, separated by 0.50 puncture diameter or less; each puncture with distinctive seta extended above cuticle

in dry specimens. Scintilla absent. Prosternum carinate, carina not produced anteriorly as very short spine; coxae separated

by thin, median carina, carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent

from anterior to posterior; median carina continued to base of intercoxal process; intercoxal process relatively narrow, sides

tapered, apex acute, width near apex 0.25 distance between internal and median carinae. Metasternum with plaques well

developed, straight, converging moderately from posterior to anterior; plaques 0.57 length of metasternum in midline;

width of each plaque slightly greater than width of intercoxal process at its midlength; plaques separated posteriorly by

slightly less than plaque width; plaques separated anteriorly by 0.50 plaque width; plaques flat in cross section; shallow

furrow lateral to each plaque. Elytra: Length 1.20 mm. Maximum width (at midlength) 0.80 mm. Surface moderately

shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures rectangular;

intervals very slightly elevated, width approximately equal to 0.50 puncture diameter, interstices between adjacent

punctures of row generally narrower; each puncture with seta. Explanate margin moderately developed, ended near apices,

with serrations near anterior angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect,

elytral margin not elevated obliquely toward suture, not in form of angle with opposite elytron. Abdomen: Intercoxal

segment concave. Glabrous segments at apex weakly produced. Segment 7 extremely weakly emarginate at apex. Legs:

Without apparent modification. Genitalia: Aedeagus as illustrated (Fig. 29A)(252 examined).

Variation. - Most specimens have the pronotal puncture density midway between the more

dense H. ancylis and the less dense H. angulicollis. However, at the rough extreme of its

sculpture cline H. pennsylvanica duplicates the form seen in H. ancylis. Likewise, at the

smooth extreme of the cline it duplicates the rough extreme of H. angulicollis. The aedeagus

characteristic of H. pennsylvanica males does not vary significantly. I have examined 610

specimens (see appendix).

Natural History. - Habitat descriptors include “brook”, “bog”, “sifting moss”, “swamp”,

“leaf litter using a Berlese funnel”, “lake shore litter”, “swamp, sphagnum”, “moss on willow

buttress”, and “Berlese, clumps of moss and grass from swampy area overgrown with willows”.

The repeated occurrence of “bog” and “ sphagnum” in the locality data suggest that this is the

preferred habitat of H. pennsylvanica. detailed study of the natural history of this species is

necessary to confirm this assertion.

Distribution. - (Figs. 25C,165B). Northeastern United States and adjacent Canada west to

Minnesota.

Quaest. Ent., 1980, 16(1,2)

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Perkins

Figs. 29A - D, Aedeagi of Hydraena species. (A) H. pennsylvanica , neotype. (B) H. ancylis, holotype. (C) H. vandykei.

(D) H. nigra , holotype.

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99

16. Hydraena ancylis new species

(Figs. 25D,29B,165B)

Type-locality. - Five miles NW Davidsburg, York County, Pennsylvania.

Type-specimens. - The holotype male is deposited in USNM. Paul Spangler and I collected

this specimen, September 3, 1972. The allotype, which is also deposited in USNM, was

collected by Paul Spangler at the same locality, July 7, 1962. Paratypes (21) are listed in the

appendix.

Diagnosis. - Most adults have the pronotum slightly more coarsely punctate and the sides

slightly more angulate than have adults of other eastern species of the circulata Group.

Additionally, the plaques are usually slightly closer together than that seen in the other species

with which H. ancylis is sympatric. Positive identification, however, should only be made after

study of the aedeagus (Fig. 29B).

Description. — Form: Elongate oval. Size: Holotype 1.80 mm long, 0.76 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi brown; antennae testaceous. Pronotum dark brown except for narrow

testaceous border at anterior and posterior. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and

inflexed margin of pronotum, brown. Head: Length 0.24 mm. Width 0.46 mm. Frons punctation coarse, narrow walls

separating punctures; microreticulation in punctures only, absent from interstices; surface dull. Frontoclypeal surface

slightly arcuate to rear. Clypeus microreticulate. Labroclypeal suture straight across middle in dorsal aspect. Labrum

bilobed, microreticulate; each lobe asymmetrical arc; median emargination ended at approximately midlength of labrum.

Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.32/0.12/0.24; palpomere 2 bent

outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; apical segment with lateral

and medial surfaces slightly arcuate; apical segment widest near apical 0.33. Mentum wider than long, surface dull, finely

microreticulate. Submentum microreticulation similar to mentum. Genae dull, finely microreticulate; area of each gena

with well developed foveola; posterior ridge well developed. Postgena with microreticulation smaller than that of

submentum. Last five antennomeres pubescent. Eyes slightly greater than 0.25 interocular distance in width. Thorax:

Pronotum length at midline 0,42 mm; maximum width (at approximately midlength) 0.60 mm; sides margined,

denticulate; sides moderately produced at middle, slightly sinuate and slightly convergent to anterior angle, sinuate and

convergent to posterior; anterior border 0.50 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

moderately arcuate to rear in middle 0.50; posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal foveolae

slightly developed; punctures in foveola closer together than those on disc. Posteroexternal foveola moderately developed.

Interfoveolar depression slightly developed. Area between external foveolae nearly flat. Anteroexternal foveolae well

developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of

pronotum. Transverse foveola very slightly developed, with punctures somewhat closer together than punctures on disc.

Disc dull, punctures separated by thin walls; each puncture with distinctive seta extended above cuticle in dry specimens.

Scintilla absent. Prosternum carinate, carina not produced anteriorly as very short spine; coxae separated by thin, median

carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to

posterior; median carina not extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered,

apex subacute, width near apex 0.50 distance between internal and median carinae. Metasternum with plaques well

developed, lateral margins parallel, medial margins weakly arcuate away from midline; plaques 0.50 length of

metasternum in midline; width of each plaque subequal to width of intercoxal process at its midlength; plaques separated

anteriorly and posteriorly by approximately plaque width; plaques flat in cross section. Elptra: Length 1.24 mm.

Maximum width (at midlength) 0.76 mm. Surface dull, disc with 10 rows of punctures between suture and humeral callus,

rows quite regular; most punctures rectangular, intervals elevated, width approximately equal to 0.33 puncture width, as

are interstices between adjacent punctures of a row; surface of each interval uneven, reflections interrupted; each puncture

with seta. Explanate margin moderately developed, ended near apices, with serrations along entire margin, those in

anterior and posterior 0.33 quite prominent. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral

margin not elevated obliquely toward suture, not in form of angle with opposite elytron. Abdomen: Intercoxal segment

concave. Glabrous segments at apex slightly produced. Segment 7 without emargination at apex. Legs: Without apparent

modification. Genitalia: Aedeagus as illustrated (Fig. 29B)(13 examined).

Variation. - Some specimens have a rather distinctive ochraceous coloration of the

pronotum.

Natural History. - The stream at the type-locality was very small, probably spring-fed. The

margin, where the beetles were found, was composed mostly of gravel and had slightly elevated,

grassy banks. Other locality data indicate “pond” and “ Sphagnum ” habitats.

Quaest. Ent., 1980, 16 (1,2)

100

Perkins

Distribution. - (Figs. 25D,165B). From Maryland west to Indiana and Missouri, then south

to Louisiana and southeasternmost Texas.

Etymology. - Greek ankylis (hook). This name refers to the hook-shaped apex of the

aedeagus.

Remarks. - The Texas locality of H. ancylis represents the southernmost known point of

distribution for the circulata Group.

17. Hydraena vandykei d’Orchymont

(Figs. 23C,29C,165B)

Hydraena vandykei d’Orchymont 1923:42 (holotype male in 1SNB; type-locality: Rossvail, Marin County, California). -

Leech and Chandler, 1956:333.

Diagnosis. - Distinguished from other members of the circulata Group, except H. sierra , by

the generally lighter color, slightly smaller pronotum with the lateral depressed areas more

explanate and the sides slightly more incised at the rear, and, especially, the rather long, dense

pubescence lateral to each metasternal plaque. The aedeagus is distinctive and must be studied

to differentiate males of H. vandykei and H. sierra.

Description. — Form: Elongate. Size: Holotype 1.88 mm long, 0.76 mm wide. Color: Dorsal surface brown.

Maxillary palpi and antennae testaceous. Ventral surface dark brown except legs, elytral epipleurae and inflexed margin of

pronotum, brown. Head: Length 0.24 mm. Width 0.42 mm. Frons dull, punctation coarse, some punctures confluent,

microreticulation most evident near eyes and in punctures. Frontoclypeal suture arcuate to posterior. Clypeus

microreticulate. Labroclypeal suture straight in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical

arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively;0.28/0. 12/0.24; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight in basal 0.33, arcuate in

apical 0.66, median surface arcuate; apical segment widest near apical 0.33. Mentum wider than long, surface moderately

shining, finely microreticulate. Submentum microreticulate. Genae moderately shining, microreticulate, lateral area of

each gena with well developed foveola; posterior ridge well developed. Postgena microreticulate. Last five

antennomeres pubescent. Eyes 0.17 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm;

maximum width (at approximately midlength) 0.54 mm; sides margined, denticulate; sides well produced at middle,

slightly sinuate and slightly convergent to anterior angle, strongly sinuate and convergent to posterior; anterior border

0.44 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50;

posterior border 0.44 mm wide, slightly arcuate to rear. Posterointernal foveolae well developed; anterior region of each

foveola nearly confluent with interfoveolar depression; punctures in foveola confluent. Antero- and posteroexternal

foveolae confluent; side of pronotum explanate. Transversal foveola well developed, with some punctures confluent. Disc

dull, punctures microreticulate, large, separated by thin walls, most punctures with seta extended above cuticle in dry

specimens. Scintilla absent. Prosternum carinate, carina not produced anteriorly as very short spine; coxae separated by

median carina slightly wider than norm; carina sinuate line in lateral aspect. Mesosternum with internal and external

carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process

relatively broad, sides tapered; apex round, width near apex 0.66 distance between internal and median carinae.

Metasternum with plaques well developed, weakly arcuate in posterior 0.50, convergent from posterior to anterior; plaques

0.57 length of metasternum in midline; width of each plaque 0.33 width of intercoxal process at midlength; plaques

separated posteriorly by approximately three times plaque width; plaques separated anteriorly by plaque width; plaques

round in cross section; area lateral to each plaque with relatively dense and long pubescence which overlaps lateral margin

of each plaque slightly. Elytra: Length 1.24 mm, maximum width (at midlength) 0.76 mm. Surface dull, disc with 10 rows

of punctures between suture and humeral callus, rows quite regular; most punctures rectangular; intervals not elevated,

width approximately equal to 0.33 puncture diameter, as are interstices between adjacent punctures of a row; each

puncture with seta. Explanate margin moderately developed, ended near apices, with extremely fine, well separated

serrations along entire margin; serrations somewhat closer near apices. Elytral apices, in dorsal aspect, gradually rounded;

in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen:

Intercoxal segment concave. Glabrous segments at apex very weakly produced. Segment 7 without emargination at apex.

Legs: Without apparent modification. Genitalia: Aedeagus as illustrated (Fig. 29C)(176 examined).

Natural History. - Most locality records cite “stream” or “creek” as habitat. This species is

primarily a psammophilous lotic form; for a detailed discussion of the microhabitat preferences

of H. vandykei and its habitat associates, refer to Perkins (1976)(7/. vandykei and H. circulata

Western Hemisphere Hydraenidae

101

are discussed in that paper under the designation “ Hydraena sp.”). Unusual habitat descriptors

seen during this study include the following, all due to the careful observation of Hugh B.

Leech: “foul pool, dried bed of creek”, “roadside seepage”, “clear water pools in gravel and

stones of otherwise dry and shaded creekbed”, and “moss-edged rock pools in running stream,

open area”.

Distribution. - (Figs. 23C,165B). Coastal mountain ranges of California. One locality is

known from Vancouver, British Columbia, but no specimens are yet known from the

intervening states of Washington and Oregon. A total of 378 specimens were examined (see

appendix).

Remarks. - The aedeagus of the holotype is distorted due to being mounted on a microslide

by a previous worker. I have therefore used another specimen to prepare the illustration.

Figs. 30A - B, Aedeagi of Hydraena sierra. (A) holotype (B) variant from Portland, Oregon.

18. Hydraena sierra new species

(Figs. 23F,30A,B,165B)

Type-locality. - North Fork San Joaquin River, at Sheep Crossing, 6000 feet, Madera

County, California.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. Hugh B. Leech collected these specimens, August 22, 1971. Paratypes (16) are listed

in the appendix.

Diagnosis. - Adults of H. sierra are distinguished from all members of the circulata Group,

except H. vandykei, by the relatively long and dense hydrofuge pubescence lateral to each

metasternal plaque. Aedeagi must be studied to differentiate males of H. sierra and H.

vandykei.

Quaest. Ent., 1980, 16 (1,2)

102

Perkins

Description. — Form: Elongate. Size: Holotype 1.84 mm long, 0.76 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi brown; antennae testaceous. Pronotum dark brown except narrow brown

border. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum, brown.

Head: Length 0.24 mm. Width 0.44 mm. Frons dull, punctation coarse, punctures separated by narrow walls;

microreticulation in punctures, absent from interstices. Frontoclypeal suture straight across middle in dorsal aspect.

Labrum bilobed, microreticulate, each lobe asymmetrical arc; median emargination ended at approximately midlength of

labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.30/0.12/0.24;

palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4

with lateral surface nearly straight in basal 0.33, arcuate in apical 0.66, median surface arcuate, apical segment widest

near apical 0.33. Mentum wider than long, surface moderately shining, microreticulate. Submentum microreticulate.

Genae dull, finely microreticulate, lateral area of each gena with a well developed foveola; posterior ridge well developed.

Postgena with microreticulation slightly smaller than that of submentum. Last five antennomeres pubescent. Eyes 0.20

interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately

midlength) 0.54 mm; sides margined, denticulate; sides well produced at middle, slightly sinuate and slightly convergent to

anterior angle, sinuate and convergent to posterior; anterior border 0.46 mm wide, straight and nearly perpendicular to

midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.46 mm. wide, slightly arcuate to rear.

Posterointernal foveolae well developed, anterior region of each foveola nearly confluent with interfoveolar depression;

punctures in foveola confluent. Antero- and posteroexternal foveolae confluent, producing explanate sides of pronotum.

Disc dull, punctation coarse, punctures separated by thin walls; microreticulation in larger punctures, absent from

interstices; most punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent, prosternum

carinate, carina not produced anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in

lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina not

extended to base of intercoxal process; intercoxal process relatively broad, sides tapered, apex round, width near apex 0.66

distance between internal and median carinae. Metasternum with plaques well developed, slightly arcuate away from

midline in posterior 0.50, convergent moderately from posterior to anterior; plaques 0.57 length of metasternum in midline;

width of each plaque 0.33 width of intercoxal process at its midlength; plaques separated posteriorly by approximately

three times plaque width; plaques separated anteriorly by twice plaque width; plaques round in cross section; area lateral to

each plaque with relatively dense and long pubescence which overlaps lateral margin of each plaque slightly. Elytra:

Length 1.24 mm. Maximum width (at midlength) 0.76 mm. Surface dull, disc with 10 rows of punctures between suture

and humeral callus, rows quite regular; most punctures rectangular; intervals not elevated, width approximately equal to

0.33 puncture diameter, as are interstices between adjacent punctures of a row; intervals and interstices with uneven

surface, reflections interrupted; punctures with seta. Explanate margin moderately developed, ended near apices, with

serrations near anterior angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect elytral

margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment concave.

Glabrous segments at apex weakly produced. Segment 7 without emargination at apex. Legs: Without apparent

modification. Genitalia: Aedeagus as illustrated (Figs. 30A-B)(9 examined).

Variation. - The specimens from the Sierra Nevada Mountains are quite homogeneous. I

have seen one male from Portland, Oregon which I am tentatively assigning to this species. The

aedeagus of this specimen (Fig. 30B) differs slightly from the aedeagi of the Sierran specimens.

Externally, this specimen is shorter, slightly broader, darker and has the elytral series less

regular. This specimen may represent another species, but such a decision must be deferred

until more material becomes available from Oregon and Washington.

Natural History. - H. sierra , like its putative sister-species H. vandykei, is probably a lotic

psammophile. Its distribution in the Sierra Nevada Mountains and its close relationship to H.

vandykei justifies this supposition; available locality data are not definitive in regard to habitat.

Distribution. - (Figs. 23F,165B). Sierra Nevada Mountains of California. One questionable

specimen known from Portland, Oregon.

Etymology. - Spanish (but seemingly Latin) noun in apposition, sierra , in reference to the

Sierra Nevada Mountains of California.

The leechi Group

Leechi Group adults are characterized by possession of posterointernal foveolae on the

pronotum (Figs. 31C,48C). In addition, the genae lack a posterior ridge ((Fig. 48E), and the

intercoxal segment of the abdomen is flat and generally with a straight posterior margin

Western Hemisphere Hydraenidae

103

(Fig. 48D).

The aedeagus is extremely varied among males of the leechi Group, variations including

origin of parameres, shape of parameres, shape of main-piece, and shape of terminal mobile

piece, when present.

Externally the group is quite diverse also, variations including shape of the pronotum,

development of a scintilla, development of microsculpture, patterns of elytral punctation, shape

of plaques, distance separating coxae, and various leg modifications (among others).

Geographically the group is very widespread, ranging from northern Argentina to southern

and northeastern United States (Fig. 160).

The leechi Subgroup

Adults included in the leechi Subgroup are relatively large, about 1.50 to 2.05 mm long,

and both sexes have a well developed scintilla (Figs. 31C,E). Males have occipital ridges

(Figs. 31D,32C), above which extends the scintilla, and also have arcuate hind tibiae which are

provided with a prominent brush of hairs in the distal 0.50 (Figs. 32D-G). Infrequently the

hind tibiae are expanded in addition to having the brush of hairs. Similarity of the basic

aedeagal form (Figs. 33A-D), which is broad in both views and has flat, lobate parameres,

provides further corroboration for the monophyly here proposed.

Individuals of this group are known from the mountains of the southwestern United States

south through the ranges of the Sierra Madre Occidental to the mountains of Oaxaca, Mexico.

Seven species are currently included in the leechi Subgroup.

19. Hydraena leechi new species

(Figs. 33A,34A, 166)

Type-locality. - Oak Creek Canyon, Midgley Bridge, Coconino County, Arizona.

Type-specimens. - The holotype male and allotype with same data are deposited in CAS.

These specimens were collected by Hugh B. Leech, August 25, 1952. Paratypes (180) are listed

in the appendix.

Diagnosis. - Specimens of H. leechi from the eastern part of its range (Fig. 34A) are easily

distinguished, being the only Hydraena with posterointernal foveolae, a large scintilla, and

males with a brush of hairs on the metatibiae. In Arizona, H. leechi is readily distinguished

from H. bituberculata and H. arizonica, both of which have posterointernal foveolae and a

large scintilla, by the form of the plaques, which are absent or reduced to small ovals in H.

leechi , tuberculate laterally in H. bituberculata (Figs. 31H,35B), and carinate in H. arizonica

(Fig. 35A). Additionally, the metatibiae of H. arizonica males are expanded in the region of

the brush of hairs (Figs. 32D,G); males of H. leechi have the metatibiae gradually enlarged

from base to apex (Figs. 32E-F). To reliably differentiate males of H. leechi from those of H.

scopula , the aedeagi must be removed and studied. H. scopula, however, is known only from

Jalisco, Mexico, which is far south of the known southwestern distributional limit of H. leechi.

Description. — Form: Elongate-oval. Size: Holotype 1.80 mm long, 0.76 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi brown; antennae brown. Pronotum dark brown except anterior and

posterior borders slightly lighter. Elytra brown, near color of anterior and posterior borders of pronotum. Ventral surface

dark brown. Head: Length 0.24 mm. Width 0.44 mm. Frons coarsely punctured, interstices approximately 0.50 puncture

diameter; interstices shining; posterior margin emarginate in midline to receive scintilla. Frontoclypeal suture straight.

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Perkins

Figs. 31 A - H, Hydraena bituberculata. (A) head of <3, dorsal aspect. (B) dorsal habitus. (C) pronotum of <3. (D) occipital

ridges of <3. (E) pronotum of 9. (F) head of 9, dorsal aspect. (G) pronotal scintilla, anterior view. (H) metasternum, oblique

view.

Western Hemisphere Hydraenidae

105

Figs. 32A - G, Hydraena arizonica and H. bituberculata. (A) H. arizonica , dorsum of head, <5. (B) H. arizonica, 3

pronotum. (C) H. arizonica , occipital ridges of <3. (D) H. arizonica, hind leg of 3. (E) H. bituberculata, hind leg of 3. (F)

H. bituberculata, hind tibia of 3. (G) H. arizonica, hind tibia of 3.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Clypeus microreticulate. Labroclypeal suture nearly straight across middle in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum.

Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.32/0.16/0.20; palpomere 2 bent

outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral

surface arcuate in basal 0.33, slightly expanded at apical 0.66, median surface sinuate; apical segment widest at

midlength. Mentum wider than long, surface moderately shining, finely punctulate. Submentum microreticulate. Genae

shining; lateral area of each gena with well developed foveola; posterior ridge very slightly developed. Postgena with

microreticulation slightly larger than that of submentum. Antennae with last 5 segments pubescent. Eyes slightly less

than 0.20 interocular distance in width. Thorax: Pronotum length at midline 0.44 mm; maximum width (slightly before

midlength) 0.56 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate and convergent

to anterior angles, very slightly sinuate and moderately convergent to posterior; anterior border 0.46 mm wide, straight

and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.50 mm

wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola similar to those on

disc. Posteroexternal foveola well developed. Interfoveolar depression well defined, discal area elevated. Area between

external foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped,

extends across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola slightly developed, with

punctures somewhat closer together than punctures on disc. Disc moderately shining, punctures relatively large and

deeply impressed, separated by thin ridges near anterior and posterior borders, by 0.50 puncture diameter in middle;

punctures with distinctive setae extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with

arcuate anterior and posterior margins. Prosternum carinate, carina produced anteriorly as very short spine; coxae

separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively

narrow, sides parallel, apex rounded, width 0.33 distance between internal and median carinae. Metasternum without

plaques. Elytra: Length 1.20 mm. Maximum width (at midlength) 0.76 mm. Surface shining, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width

approximately equal to 0.50 puncture diameter, interstices between adjacent punctures of row generally narrower;

punctures each with seta. Explanate margin quite narrow, with extremely fine, well separated serrations near anterior

angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated

obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long,

posterior margin arcuate. Glabrous segments at apex moderately produced, length subequal to that of metasternum in

midline. Apical segment slightly emarginate at apex. Legs: Profemur with small tubercle on inner surface near basal

0.33. Protibia very slightly arcuate, prominent spine on inner surface at apical 0.33. Metafemur broad, lateral surface

markedly arcuate, median surface sinuate. Metatibiae gradually enlarged from base to apex; arcuate in basal 0.50; with

prominent brush of hairs at apical 0.33. Genitalia: Aedeagus as illustrated (Fig. 33A)(92 examined).

Variation. - No significant variation was noted in the 180 specimens studied.

Natural History. - The scant habitat data available include the notations, “in moss and

grass roots along stream”, “along creek edge”, “spring”, and “pools, bed below Yank’s Spring”.

Distribution. - (Figs. 34A,166). Southeastern Arizona south to northwestern Mexico and

east to southern Oklahoma.

Etymology. - It is with great pleasure that I dedicate this species to Hugh B. Leech, in

recognition of his many contributions to the study of aquatic beetles in general, and to this

study in particular.

20. Hydraena breedlovei new species

(Figs. 33B, 166)

Type-locality. - Two miles E. of Durango-Sinaloa boundary on highway MEX. 40, 7000

feet, Durango, Mexico.

Type-specimens. - The holotype male and allotype with same data are deposited in CAS.

These specimens were collected by D.E. Breedlove and J.F. Copp on December 30, 1962.

Paratypes (34) are listed in the appendix.

Diagnosis. - Small size (1.48 mm long), strongly arcuate metatibiae which are provided

with a brush of hairs in males, and moderately broad form serve to characterize this species.

Plaques are thin arcuate lines, barely distinguishable, not shiny and therefore not contrasting

Western Hemisphere Hydraenidae

107

with remainder of metasternum; they are, however, very slightly elevated in males.

Figs. 33A - D, Aedeagi of Hydraena holotypes. (A) H. leechi. (B) H. breedlovei. (C) H. arizonica. (D) H. bituberculata.

Description. — Form: Subovate. Size: Holotype 1.48 mm long, 0.64 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi brown; antennae brown. Pronotum with disc dark brown, lateral areas

lighter. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum, brown.

Head: Length 0.20 mm. Width 0.40 mm. Frons coarsely punctured, interstices less than puncture diameter; interstices

shining; posterior margin emarginate in midline to receive scintilla. Frontoclypeal suture straight. Clypeus microreticulate.

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Perkins

Labroclypeal suture nearly straight across in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc;

median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively; 0.24/0.10/0.16; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight; median surface arcuate;

apical segment widest at midlength. Mentum wider than long, surface moderately shining, microreticulate. Submentum

microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge imperceptible.

Postgena with punctation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly less

than 0.25 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (slightly before

midlength) 0.54 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate and moderately

convergent to anterior angle, very slightly sinuate and moderately convergent to posterior; anterior border 0.42 mm

wide, straight and nearly perpendicular to midline in lateral 0.25; slightly arcuate to rear in middle 0.50; posterior

border 0.46 mm wide, slightly arcuate to rear. Posterointernal foveolae slightly developed; punctures in foveola similar

to those on disc. Posteroexternal foveola well developed. Interfoveolar depression relatively shallow. Area between

external foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped,

occupying slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in

this area somewhat closer together than punctures on disc. Disc slightly shining, punctures coarse, separated by thin

ridges near anterior and posterior borders, and 0.50 puncture diameter or less in middle; punctures with distinctive setae

extended above cuticle in dry specimens. Larger interstices with minute reflections, cuticle with appearance of tiny

reflecting surfaces within. Scintilla distinct, flat, impuntate shelf with arcuate anterior and posterior margins.

Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina

sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior;

median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides nearly parallel, apex

blunt, width at apex 0.33 distance separating internal and median carinae. Metasternum with plaques weakly developed,

arcuate, convergent rather markedly from posterior to anterior; plaques nearly 0.50 length of metasternum in midline;

each plaque thin, moderately elevated ridge. Elytra: Length 1.00 mm. Maximum width (at midlength) 0.64 mm.

Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures

round; intervals not elevated, width approximately 0.50 puncture diameter, interstices between adjacent punctures of

row generally narrower; punctures each with seta. Explanate margin quite narrow, ended near posterior 0.17, with

extremely fine, well separated serrations near anterior angles and apices. Elytral apices, in dorsal aspect, gradually

rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite elytron.

Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous segments at apex moderately

produced. Apical segment without emargination at apex. Legs: Profemur with minute tubercle on inner surface near

basal 0.33. Protibia slightly arcuate, prominent spine on inner surface at apical 0.33. Metafemur broad; lateral surface

markedly arcuate; median surface sinuate. Metatibia slightly expanded, with prominent brush of hairs at apical 0.33;

basal 0.50 arcuate. Genitalia: Aedeagus as illustrated (Fig. 33B)( 1 7 examined)

Natural History. - I have collected adults of this species from sand and gravel at the margin

of a stream flowing through a pine forest in the mountains of Durango, Mexico.

Distribution. - (Fig. 166). As presently known, restricted to the mountains of Durango,

Mexico.

Etymology. - It is my pleasure to acknowledge the request of Hugh Leech, who had

recognized this species as undescribed, and to dedicate it to D. E. Breedlove, Chairman of the

Department of Botany, California Academy of Sciences.

21. Hydraena arizonica new species

(Figs. 10J,32A-D,G,33C,34A,35A,166)

Type-locality. - Madera Canyon, 6200 feet, Santa Rita Mountains, Santa Cruz County,

Arizona.

Type-specimens. - The holotype male and allotype with identical data are deposited in

CAS. These specimens were collected by Hugh B. Leech, August 1, 1952. Paratypes (47) are

listed in the appendix.

Diagnosis. - Straight, carinate plaques (Fig. 3 5 A) serve to readily distinguish specimens of

Hydraena arizonica from other species whose adults also possess a well developed scintilla.

Additionally, males have the metatibiae expanded and with a brush of hairs (Figs. 32D,G).

Western Hemisphere Hydraenidae

109

Description. — Form: Elongate. Size: Holotype 1.76 mm long, 0.72 mm wide. Color: Dorsal surface dark brown;

maxillary palpi brown; antennae brown. Ventral surface dark brown except legs brown. Head: Length 0.20 mm. Width

0.40 mm. Frons coarsely punctured, interstices usually less than 0.50 puncture diameter; interstices shining; posterior

margin emarginate in midline to receive scintilla. Labroclypeal suture straight. Clypeus microreticulate. Labroclypeal

suture weakly arcuate when viewed from above. Labrum bilobed, microreticulate, each lobe symmetrical arc; median

emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.24/0.12/0.18; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface arcuate in basal 0.33, slightly expanded at

apical 0.66, median surface sinuate; palpomere 4 widest at midlength. Mentum wider than long, surface moderately

shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of each gena with well developed

foveola; posterior ridge nearly imperceptible. Postgena with microreticulation slightly larger than that of submentum. Last

five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at

midline 0,44 mm; maximum width (slightly before midlength) 0.56 mm; sides margined, denticulate; sides moderately

produced at middle, slightly arcuate and slightly convergent to anterior angle, very slightly sinuate and convergent to

posterior; anterior border 0.46 mm wide, straight and nearly perpendicular to midline in lateral 0.25, slightly arcuate to

rear in middle 0.50; posterior border 0.48 mm wide, slightly arcuate to rear. Posterointernal foveolae well developed;

punctures in foveola similar to those on disc. Posteroexternal foveola well developed. Interfoveolar depression well defined,

discal area elevated. Area between external foveolae moderately elevated. Anteroexternal foveolae well developed, each

foveola somewhat crescent shaped, extended across less than 0.33 width of anterior region of pronotum. Transverse foveola

not developed, punctures in this area somewhat closer together than punctures on disc. Disc slightly shining, punctures

relatively large and deeply impressed, separated by thin ridges near anterior and posterior borders, and 0.50 puncture

diameter or less in middle; punctures with setae extended above cuticle in dry specimens. Larger interstices with minute

reflections, cuticle apparently with tiny reflecting surfaces within. Scintilla distinct, flat, impunctate shelf with arcuate

anterior and posterior margins. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by

thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from

anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides

parallel, apex blunt, width at apex 0.33 distance between internal and median carinae. Metasternum with plaques

moderately developed, straight, convergent very slightly from posterior to anterior; plaques nearly 0.50 length of

metasternum in midline; each plaque thin, moderately elevated ridge. Elytra: Length 1.12 mm. Maximum width (at

midlength) 0.72 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width approximately equal to 0.50 puncture diameter, as are

interstices between adjacent punctures of a row; punctures each with perceptible seta. Explanate margin quite narrow,,

ended near posterior 0.17, with extremely fine, well separated serrations near anterior angles and apices. Elytral apices, in

dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with

opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous segments at apex

moderately produced. Apical segment without emargination at apex. Legs: Profemur with small tubercle on inner surface

near basal 0.33. Protibia very slightly arcuate, prominent spine on inner surface at apical 0.33. Metafemur broad, lateral

surface markedly arcuate, median surface sinuate. Metatibia expanded and with brush of hairs on inner surface near

apical 0.25, basal 0.50 arcuate. Genitalia: Aedeagus as illustrated (Fig. 33C)(27 examined).

Natural History. - Locality data include the notations “along creek edge” and “ex under

stones in small creek in mountains, 2500 meters”.

Distribution. - (Figs. 34A,166). Known from the mountains of southeastern Arizona and

Durango, Mexico.

Etymology. - Latin, arizonica , in reference to location of the type locality.

22. Hydraena bituberculata new species

(Figs. 31 A-H,32E-F,33D,34B,35B-C,166)

Type-locality. - South Fork Cave Creek, 4.5 miles W. Portal, Cochise County, Arizona.

Type-specimens. - The holotype male is deposited in CAS. This specimen was collected by

Hugh B. Leech, July 30, 1965. The allotype, also deposited in CAS, was collected by P. H.

Arnaud, Jr. at the Southwest Research Station in the same county, October 24, 1964.

Paratypes (52) are listed in the appendix.

Diagnosis. - Among those species with a well developed scintilla, H. bituberculata is unique

in possession of a tubercle lateral to each metasternal plaque. (Figs. 31H,35B). Males have a

well developed brush of hairs on the metatibiae.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Figs. 34A - B, Geographical distributions of Hydraena species. (A) H. leechi • , H. arizonica ★ and H. scopula A •

(B) H. bituberculata • , H. alternata ★ and H. scintilla A •

Figs. 35A - C. (A) Hydraena arizonica, metasternum. (B) H. bituberculata, metasternum. (C) H. bituberculata, 2

abdominal apex.

Western Hemisphere Hydraenidae

111

Description. — Form: Elongate. Size: Holotype 1 .92 mm long, 0.76 mm wide. Color: Head with dorsal surface dark

brown; labrum brown; maxillary palpi brown; antennae testaceous. Pronotum with disc dark brown, lateral areas lighter.

Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum, brown. Head:

Length 0.24 mm. Width 0.44 mm. Frons coarsely punctured, interstices in midline equal to or slightly greater than

puncture diameter; surface shining; posterior margin emarginate in midline to receive scintilla. Frontoclypeal suture

straight. Clypeus finely microreticulate at sides, glabrous in midline. Labroclypeal suture nearly straight across middle in

dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended slightly before

midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.28/0.16/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface very slightly arcuate 0.33, very slightly expanded at apical 0.66, median very

slightly sinuate; palpomere 4 widest slightly past midlength. Mentum wider than long, surface moderately shining,

microreticulate. Submentum microreticulate. Genae shining; lateral area of each gena with well developed foveola;

posterior ridge slightly developed. Postgena with microreticulation slightly larger than that of submentum. Last five

antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at midline

0.44 mm; maximum width (at approximately midlength) 0.60 mm; sides margined, denticulate; sides moderately produced

at middle, nearly straight and convergent to anterior angle, very slightly concave and convergent to posterior; anterior

border 0.48 mm wide, straight and nearly perpendicular to midline in lateral 0.20, moderately arcuate to rear in middle

0.60; posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in

foveola similar to those on disc. Posteroexternal foveola well developed. Interfoveolar depression well defined, discal area

elevated. Area between external foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola

somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola

slightly developed, punctures separated by narrow ridges. Disc shining, punctures relatively large and deeply impressed,

separated by thin ridges near anterior and posterior borders, by puncture diameter in middle; punctures with distinctive

seta extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin.

Prosternum carinate, carina produced anteriorly into very short spine; coxae separated by thin, median carina; carina

sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent slightly from anterior to posterior;

median carina extended to base of intercoxal process; intercoxal process relatively narrow, increased very slightly in width

from base to apex, apex blunt, width at apex 0.50 distance between internal and median carinae. Metasternum with

prominent tubercle immediately lateral to each plaque; each plaque small oval at posterior 0.25 of metasternum. Elytra:

Length 1.22 mm. Maximum width (at midlength) 0.76 mm. Surface shining, disc with 10 rows of punctures between

suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal to

0.50 puncture diameter, interstices generally narrower; punctures each with perceptible seta. Explanate margin quite

narrow, ending near posterior 0.17, with extremely fine, well separated serrations near anterior angles and apices. Elytral

apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of

angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin arcuate. Glabrous

segments at apex moderately produced. Apical segment slightly emarginate at apex. Legs: Profemur with carinate tubercle

on inner surface near basal 0.20; prominent spine on inner surface at apical 0.33. Metafemur broad; lateral surface

markedly arcuate; median surface sinuate. Metatibia slightly expanded with prominent brush of hairs at apical 0.33; basal

0.50 arcuate. Genitalia: Aedeagus as illustrated (Fig. 33D)(33 examined).

Natural History. - Apart from the notation “stream banks”, nothing is known concerning

the habitat of this species.

Distribution. - (Figs. 34B,166). Known only from Cochise County in Arizona and Dona

Ana County in New Mexico.

Etymology. - Latin, bi (two) plus tuberculum (small swelling). Named in reference to the

two metasternal tubercles.

23. Hydraena scintilla new species

(Figs. 34B,36B,D,166)

Type-locality. - One mile N. Ixtlan de Juarez, Oaxaca, Mexico.

Type-specimens. - The holotype male and allotype with same data are deposited in USNM.

These specimens were collected by my wife and I, July 5, 1974. One male paratype (PDP) has

the following data: Intermittent desert stream, 2 miles N. Zimapan, Hidalgo, Mexico, May 21,

1974, M.E. and P.D. Perkins. One paratype of each sex (CAS) has the following data: Mexico,

San Luis Potosi, Ciudad del Maiz, 9-1-1971, J.T. Polhemus.

Quaest. Ent., 1980, 16 (1,2)

112

Perkins

Diagnosis. - Large size (1.92-2.02 mm), males with an excavation at the apex of the

protibiae and a cariniform prominence on the inner surface of the profemora, plus aedeagal

form (Figs. 36B,D), serve to distinguish this species from others whose adults also possess a

brush of hairs on the metatibiae (males) and a well developed scintilla (both sexes).

Description. — Form: Elongate. Size: Holotype 1.92 mm long, 0.82 mm wide. Color: Dorsal surface dark brown;

labrum dark brown; maxillary palpi brown except apices dark brown; antennae testaceous. Ventral surface dark brown

except legs, elytral eipipleura and inflexed margin of pronotum brown. Head: Length 0.24 mm. Width 0.44 mm. Frons

coarsely punctured, interstices approximately 0.50 puncture diameter, or less; surface shining; posterior margin

emarginate to receive scintilla. Frontoclypeal suture straight. Clypeus microreticulate laterally, shining in midline.

Labroclypeal suture nearly straight across middle in dorsal aspect. Labrum bilobed, microreticulate, each lobe

symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.32/0.16/0.20; palpomere 2 bent outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 arcuate in basal 0.17, straight in remainder,

median surface sinuate; palpomere 4 widest slightly past midlength. Mentum wider than long, surface moderately shining,

finely punctulate. Submentum microreticulate. Genae shining; lateral area of each gena with well developed foveola;

posterior ridge very slightly developed. Postgena with punctation slightly larger than that of submentum. Last five

antennomeres pubescent. Eyes slightly greater than 0.20 interocular distance in width. Thorax: Pronotum length at

midline 0.48 mm; maximum width (at approximately midlength) 0.62 mm. sides margined, denticulate; sides moderately

produced at middle, slightly arcuate and convergent to anterior angle, very slightly sinuate and moderately convergent to

posterior; anterior border 0.48 mm wide, straight and nearly perpendicular to midline in lateral 0.25, slightly arcuate to

rear in middle 0.50; posterior border 0.54 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately

developed; punctures in foveola similar to those on disc. Posteroexternal foveola well developed. Interfoveolar depression

well defined, discal area elevated. Area between external foveolae well elevated. Anteroexternal foveolae well developed,

each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum.

Transverse foveola slightly developed, with punctures separated by thin walls. Disc moderately shining, punctures

relatively large and deeply impressed, separated by thin walls; punctures with distinctive setae extended above cuticle in

dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin. Prosternum carinate, carina produced

anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum

with internal and external carinae divergent from anterior to posterior; median carina extended to base of intercoxal

process; intercoxal process relatively narrow, sides nearly parallel, apex blunt, width at apex nearly 0.66 distance between

internal and median carinae. Metasternum with plaques weakly developed, of small ovals at posterior 0.20 of

metasternum. Elytra: Length 1.28 mm. Maximum width (at midlength) 0.82 mm. Surface shining, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width

approximately equal to 0.50 puncture diameter, interstices between adjacent punctures of row generally narrower;

punctures each with seta. Explanate margin quite narrow, with extremely fine, well separated serrations near anterior

angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely

toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin

arcuate. Glabrous segments at apex moderately produced. Apical segment slightly emarginate at apex. Legs: Profemur

with cariniform tubercle on inner surface near basal 0.33. Protibia excavate on inner surface at apex; prominent spine on

inner surface at apical 0.33. Metafemur broad, lateral surface markedly arcuate, median surface sinuate. Metatibia

gradually enlarged from base to apex; arcuate in basal 0.50; with prominent brush of hairs near apical 0.33. Genitalia:

Aedeagus as illustrated (Figs. 36B,D)(3 examined).

Variation. - The aedeagus of the male from Hidalgo differs slightly from that of the

holotype (Fig. 36D).

Natural History. - Specimens from the type-locality were removed from leaves which had

become trapped behind water-soaked branches in a moderately large stream (Fig. 195B). Also

taken from the leaves were specimens of H. cuspidicollis. The single male from Hidalgo was

collected from sand and gravel at the margin of a very small, intermittent desert stream;

Ochthebius obscurus adults were also taken at this locality.

Distribution. - (Figs. 34B,166). Known from the states of San Luis Potosi, Hidalgo and

Oaxaca, Mexico.

Etymology. - Latin, scintilla (spark). Named in reference to the well developed pronotal

scintilla.

Western Hemisphere Hydraenidae

113

24. Hydraena canticacollis new species

(Figs. 36C,166)

Type-locality. - Thirteen miles S. Jalpa, Zacatecas, Mexico.

Type-specimen. - The holotype male (unique) is deposited in USNM. My wife and I

collected this specimen, July 16, 1974.

Diagnosis. - Readily distinguished by form of the metasternal plaques which are short but

very markedly carinate. Each plaque is very sharp, nearly as high as long, and has the anterior

extreme gradually tapered to the level of the remainder of the metasternum while the posterior

extreme is extended abruptly above the surrounding area. The pronotum is also distinctive by

virtue of its coarse, widely spaced punctures on the disc; some punctures are separated by twice

their diameters.

Description. — Form: Elongate. Size: Holotype 1.76 mm long, 0.76 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous except apices brown; antennae testaceous. Pronotum dark brown

except anterior and posterior borders, slightly lighter. Elytra brown. Ventral surface dark brown except legs, elytral

epipeura and inflexed margin of pronotum brown. Head: Length 0.24 mm. Width 0.42 mm. Frons coarsely punctured,

interstices less than puncture diameter; surface moderately shining; posterior margin emarginate in midline to receive

scintilla. Frontoclypeal suture straight. Clypeus microreticulate in lateral areas, shining in midline. Labroclypeal suture

arcuate in dorsal aspect. Labrum bilobed; surface punctulate; each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.32/0.16/0.22; palpomere 2 bent outward at approximately midlength; apex of palpomere 3 relatively expanded;

palpomere 4 with lateral surface arcuate in basal 0.17, straight in remainder, median surface sinuate; apical segment

widest slightly past midlength. Mentum wider than long, surface moderately shining, finely punctulate. Submentum

microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge nearly imperceptible.

Postgena with microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly

less than 0.20 interocular distance in width. Thorax: Pronotum length at midline 0.44 mm; maximum width (at

approximately midlength) 0.60 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate

and moderately convergent to anterior angles, very slightly sinuate and moderately convergent to posterior; anterior border

0.48 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50;

posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in

foveola closer together than those on disc. Posteroexternal foveola well developed. Interfoveolar depression well defined,

discal area elevated. Area between external foveolae moderately elevated. Anteroexternal foveolae well developed, each

foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum. Transverse

foveola slightly developed, punctures somewhat closer together than punctures on disc. Disc moderately shining, punctures

relatively large and deeply impressed, separated by 0.33 puncture diameter near anterior and posterior borders, punctures

in middle, very unevenly spaced, some interstices thin walls, other equal to twice puncture diameter; punctures without

distinctive setae extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind

margin. Prosternum carinate, carina produced anteriorly into a very short spine; coxae separted by thin median carina;

carina a sinuate line when viewed laterally. Mesosternum with internal and external carinae diverging from anterior to

posterior; median continuing to base of intercoxal process; intercoxal process relatively narrow, wider at apex than at base,

apex blunt, width at base 0.33 distance between internal and median carinae. Metasternum with plaques small, carinate,

moderately well elevated, posterior margin truncate. Elytra: Length 1.14 mm. Maximum width (at midlength) 0.76 mm.

Surface moderately shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular;

punctures round; intervals not elevated, width approximately 0.50 puncture diameter, interstices between adjacent

punctures of row approximately 0.25 puncture diameter; punctures each with seta. Explanate margin quite narrow, ended

near posterior 0.20, with extremely fine, well separated serrations along entire margin; serrations somewhat closer near

apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytrai margin extended obliquely toward

suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin

arcuate. Glabrous segments at apex well produced. Apical segment slightly emarginate at apex. Legs: Profemur with small

tubercle on inner surface near basal 0.33. Protibia excavate on inner surface at apex. Metafemur broad, lateral surface

strongly arcuate, median surface sinuate. Metatibia gradually enlarged from base to apex; arcuate in basal 0.50; with

prominent brush of hairs at apical 0.33. Genitalia: Aedeagus as illustrated (Fig. 36C)(1 examined).

Natural History. - This specimen was collected from loose sand at the margin of a stream

outwash area (Fig. 189C). The stream was flowing through a desert habitat. The microhabitat

also contained adults of Limnebius sinuatus.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Figs. 36A - D, Aedeagi of Hydraena species. (A) H. scopula, holotype. (B) H. scintilla , holotype. (C) H. canticacollis,

holotype. (D) H. scintilla , variant from Hidalgo, Mexico.

Distribution. - (Fig. 166). Known only from type-locality near Jalpa in Zacatecas, Mexico.

Etymology. - Latin, cantica (musical) plus collis (neck). This name refers to the scintilla of

the pronotum and its supposed stridulatory function. It is also an attempt at onomatopoeia.

Western Hemisphere Hydraenidae

115

25. Hydraena scopula new species

(Figs. 34A,36A,166)

Type-locality. - Seven miles S. Mazamitla, Jalisco, Mexico.

Type-specimens. - The holotype male and allotype with same data are deposited in USNM.

My wife and I collected these specimens July 15, 1974; two male paratypes (PDP) were also

taken at that time. Other paratypes include specimens collected by Hugh B. Leech (CAS):

type-locality, December 1, 1948 (2 females); 20 miles W. Jiquilpan, November 30, 1948 (1

male).

Diagnosis. - Among those species whose males have a well developed scintilla and a

metatibial brush of hairs, H. scopula is very similar, externally, to H. leechi. The only reliable

way to differentiate specimens of these two species is by characters of the male genitala

(Fig. 36A).

Description. — Form: Elongate. Size: Holotype 1.76 mm long, 0.74 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi brown; antennae brown. Pronotum with disc dark brown, lateral areas lighter.

Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head:

Length 0.24 mm. Width 0.42 mm. Frons coarsely punctured, interstices less than puncture diameter; interstices shining;

posterior margin emarginate in midline to receive scintilla. Frontoclypeal suture straight. Clypeus microreticulate.

Labroclypeal suture nearly straight across middle in dorsal aspect. Labrum bilobed, microreticulate, each lobe

symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.28/0.14/0.18; palpomere 2 bent outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface slightly arcuate in basal

0.25, nearly straight in apical 0.75, median surface sinuate; palpomere 4 widest slightly past midlength. Mentum wider

than long, surface moderately shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of each

gena with well developed foveola; posterior ridge very slightly developed. Postgena with microreticulation on slightly larger

than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width.

Thorax: Pronotum length at midline 0.44 mm; maximum width (at approximately midlength) 0.58 mm; sides margined,

denticulate; sides moderately produced at middle, nearly straight and slightly convergent to anterior angle, very slightly

concave and convergent to posterior; anterior border 0.48 mm wide, straight and nearly perpendicular to midline in lateral

0.20, moderately arcuate to rear in middle 0.60, posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal

foveolae moderately developed; punctures in foveola similar to those on disc. Posteroexternal foveola well developed.

Interfoveolar depression well defined, discal area elevated. Area between external foveolae slightly elevated.

Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across 0.25 width of anterior

region of pronotum. Transverse foveola slightly developed, punctures separated by thin walls. Disc moderately shining,

punctures relatively large and deeply impressed, separated by thin walls near anterior and posterior borders, and by 0.50

puncture diameter in middle; some punctures with distinctive seta extended above cuticle in dry specimens. Scintilla

distinct, flat, impunctate shelf with arcuate anterior and posterior margins. Prosternum carinate, carina produced

anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum

with internal and external carinae divergent from anterior to posterior; median carina extended to base of intercoxal

process; intercoxal process relatively narrow, sides nearly parallel, apex blunt, width at apex 0.33 distance between internal

and median carinae. Metasternum with plaques weakly developed, of small ovals at posterior 0.20 of metasternum. Elytra:

Length 1.10 mm. Maximum width (at midlength) 0.74 mm. Surface shining, disc with 10 rows of punctures between

suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal to

0.33 puncture diameter, interstices generally narrower; punctures each with perceptible seta. Explanate margin quite

narrow, ending near posterior 0.17 with extremely fine, well separated serrations near anterior angles and apices. Elytral

apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of

angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin arcuate. Glabrous

segments at apex moderately produced. Segment 7 without emargination at apex. Legs: Profemur with small tubercle on

inner surface near basal 0.33. Protibia with prominent spine on inner surface at apical 0.33. Metafemur moderately broad,

lateral surface arcuate, median surface sinuate. Metatibia gradually enlarged from base to apex; arcuate in basal 0.50;

prominent brush of hairs on inner surface at apical 0.33. Genitalia: Aedeagus as illustrated (Fig. 36A)(4 examined).

Natural History. - The type-locality consists of a moderately fast, pine forest stream. The

substratum at the margin of the stream contained a higher percentage of mud than is usually

seen in hydraenid streams. Consocies included H. mazamitla , H. cuspidicollis and H.

crystallina.

Quaest. Ent., 1980, 16 (1,2)

116

Perkins

Distribution. - (Figs. 34A,166). Known only from the state of Jalisco, Mexico.

Etymology. - Latin, scopula (small broom). I refer to the brush of hairs present on the

metatibiae of males.

The alternata Subgroup

This subgroup presently consists of a single unusual species, H. alternata , from the

mountains of Durango, Mexico. The elytra are broadly explanate and have alternate intervals

elevated slightly. The latter feature is unique among Western Hemisphere Hydraena. As in the

lee chi Subgroup, both sexes have a well developed scintilla, and the hind tibiae of males are

arcuate. However, the brush of hairs found on the hind tibiae of leechi Subgroup adults is

replaced by two stiff spines in H. alternata adults. Further, the hind femora of H. alternata

males have a group of prominent, curved hairs on the inner surface; these hairs are not as well

developed in members of the leechi Subgroup.

The aedeagus of H. alternata males (Fig. 37A) is of a different basic form than that of the

leechi Subgroup, providing additional justification for placing it in a separate subgroup.

According to d’Orchymont (1936:18), Kuwert’s (1888) subgenus Taenhydraena has

elevated alternate elytral intervals also. The aedeagal illustration presented by d’Orchymont

(1936:39) for the single species of this subgenus, H. exarata Kiesenwetter, differs greatly from

that of H. alternata. Most likely the elytral charac eristics of these two species have been

independently derived, and are of species-group significance only.

26. Hydraena alternata new species

(Figs. 34B,37A)

Type-locality. - Three miles E. La Ciudad, Durango, Mexico.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. Paul J. Spangler collected these specimens, July 1, 1964. Paratypes (27) are listed

in the appendix.

Diagnosis. - Readily distinguished from all other Western Hemisphere Hydraena by the

broadly explanate elytra which have elevated alternate intervals. The pronotum is coarsely

punctate, each puncture with a short but distinctive seta; the interstices are very convex and

shiny. Males have the metatibiae arcuate and with two spines on the inner surface near the

distal 0.25; the metafemora are prominently pubescent on the inner surface.

Description. — Form: Elongate-oval. Size: Holotype 1.92 mm long, 0.84 mm wide. Color: Dorsal surface and

labrum dark brown; maxillary palpi and antennae testaceous. Ventral surface dark brown except legs, elytral eipileura and

inflexed margin of pronotum brown. Head: Length 0.24 mm. Width 0.44 mm. Frons coarsely punctured, some punctures

nearly confluent; interstices shining; posterior margin slightly emarginate to receive scintilla. Frontoclypeal suture

straight. Clypeus microreticulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate and

setose; each lobe symmetrical arc; median emargination ended above midlength of labrum. Maxillary palpus with

following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.32/0.14/0.22; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight, median surface evenly, extremely slightly arcuate; palpomere 4 widest slightly past midlength. Mentum wider

than long, surface moderately shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of each

gena with well developed foveola; posterior ridge weakly developed. Postgena with microreticulation slightly larger than

that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.17 interocular distance in width. Thorax:

Pronotum length at midline 0.44 mm; maximum width (at approximately midlength) 0.62 mm; sides margined,

denticulate; sides moderately produced at middle, slightly arcuate and convergent to anterior angle, sinuate and

convergent to posterior; anterior border 0.48 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

Western Hemisphere Hydraenidae

117

Figs. 37 A - B, Aedeagi of Hydraena holotypes. (A) H. alternata. (B) H. campbelli.

moderately arcuate to rear in middle 0.50, posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal

foveolae well developed; punctures in foveola similar to those on disc. Posterointernal, anteroexternal foveolae and

interfoveolar depression all confluent, in form of distinct, explanate surface. Anteroexternal foveolae well developed,

each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum.

Transverse foveola slightly developed, punctures separated by thin walls. Disc relatively dull, punctures large, deep and

close set; interstices approximately 0.50 puncture diameter, rounded, on various levels, appearance somewhat rugulose,

punctures each with seta extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate

hind margin, prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin, median

carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to

posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered, apex

blunt, width at apex 0.33 distance between internal and median carinae. Metasternum with plaques moderately

developed, triangular, median surfaces nearly parallel; 0.38 length of metasternum in midline; plaques flat in cross

section. Elytra: Length 1.32 mm. Maximum width (at midlength) 0.84 mm. Surface shining, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures round; intervals 2, 4, 6, 8 and 10

(numbered from suture) markedly elevated; width of all intervals approximately equal to puncture diameter; adjacent

punctures of row nearly contiguous; each puncture with seta. Explanate margin broad, extended to apices, with

serrations along entire margin; serrations slightly closer near apices. Elytral apices, in dorsal aspect, gradually rounded;

in posterior aspect, elytral margin elevated very slightly, obliquely toward suture, in form of angle with opposite elytron.

Abdomen: Intercoxal segment flat, nearly equilateral triangle, posterior margin arcuate. Glabrous segments at apex

weakly produced. Segment 7 with emargination at apex. Legs: Protibia excavate on inner surface at apex. Metatibia

arcuate, with two prominent spines on inner surface at apical 0.25. Metafemur prominently pubescent on inner surface.

Genitalia: Aedeagus as illustrated (Fig. 37A)(14 examined).

Natural History. - Hans Reichardt collected this species in association with Hydraena

prieto “ex under stones in a small creek in the mountains”. I have collected it at the margin of a

Quaest. Ent., 1980, 16 (1,2)

118

Perkins

stream flowing through a pine forest meadow in the mountains of Durango, Mexico. The

margins of this stream were composed of rather hard-packed gravel; consocies included

Ochthebius madrensis and O. mexcavatus.

Distribution. - (Fig. 34B). The mountains of Durango, Mexico.

Etymology. - Latin, alternata (alternating). This name refers to the elevated alternate

intervals of the elytra.

The scintillabella Subgroup

Most members of this subgroup, like those of the leechi and alternata Subgroups, have a

well developed scintilla. However, males have the metatibiae straight, without a brush of hairs

or prominent spines. Males of the leechi Subgroup have the metatibiae markedly arcuate and

with a brush of hairs (Fig. 32D), whereas those of the alternata Subgroup are likewise arcuate

but have two prominent spines near the distal 0.25.

Adults of a few species of the scintillabella Subgroup, such as H. terralta and H. alterra,

have the scintilla quite narrow, while in others, such as H. colombiana and H. exilipes , it is

barely perceptible. In H. ozarkensis adults, the scintilla is apparent in males, barely perceptible

in certain females, and imperceptible in other females. In H. zapatina adults a scintilla is not

apparent, although the pronotum is very smooth in the appropriate location, in males.

Aedeagal affinities, which form morphoclines, help “tie” problem species characterized by

absence of a scintilla, to their close relatives which have the scintilla more apparent. A

discussion of this topic is developed in more detail in the section on phylogeny.

The scintillabella Subgroup, which currently consists of 17 species, ranges from the eastern

United States (Ozark Plateau and Appalachian Mountains) south through Mexico to

Paraguay.

27. Hydraena scintillabella new species

(Figs. 38B, 167)

Type-locality. - 23 km. E. El Colegio, Cundinamarca, Colombia.

Type-specimen. - The holotype male (unique) is deposited in USNM. Paul and Phyllis

Spangler collected this specimen, March 9, 1969.

Diagnosis. - The well developed scintilla, absence of plaques, plus the dark coloration and

smooth, shiny dorsum combine to make adults of this attractive species very distinctive. The

pronotal fascia and head are a deep, rich dark brown, contrasting attractively with the

testaceous palpi. The reflected light passing through the scintilla produces an amber glow. The

hydrofuge pubescence of the metasternum appears to be slightly longer in the region usually

occupied by plaques.

Description. — Form: Elongate. Size: Holotype 1 .64 mm long, 0.66 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum light brown at anterior and

posterior 0.25, dark brown in center 0.50; sides slightly lighter than center. Elytra brown. Ventral surface dark brown

except legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width 0.40 mm. Frons

finely and sparsely punctured, many interstices five times puncture diameter; surface very shiny; posterior margin not

emarginate. Frontoclypeal suture straight. Clypeus finely and sparsely punctulate, very shiny except at extreme sides.

Labroclypeal suture slightly arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median

emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.28/0.12/0.22; palpomere 2 bent outward at approximately midlength; apices of

Western Hemisphere Hydraenidae

119

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight in basal 0.33, arcuate in

apical 0.66, median surface evenly, extremely slightly arcuate; palpomere 4 widest slightly past midlength. Mentum

wider than long, surface shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of each

gena with well developed foveola; posterior ridge absent. Postgena with microreticulation slightly larger than that of

submentum. Last five antennomeres pubescent. Eyes slightly less than 0.17 interocular distance in width. Thorax:

Pronotum length at midline 0.40 mm; maximum width (at approximately midlength) 0.54 mm; sides margined,

denticulate; sides moderately produced at middle, slightly arcuate and convergent to anterior angle, slightly sinuate and

convergent to posterior; anterior border 0.44 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

moderately arcuate to rear in middle 0.50; posterior border 0.48 mm wide, slightly arcuate to rear. Posterointernal

foveolae moderately developed; punctures in foveola similar to those on disc. Posteroexternal foveolae moderately

developed. Interfoveolar depression slightly developed. Area between external foveolae weakly elevated. Anteroexternal

foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of

anterior region of pronotum. Transverse foveola not developed, punctures in this area somewhat closer together than on

disc. Disc extremely shiny, punctures fine, separated by puncture diameter near anterior and posterior borders, and by

two to three times puncture diameter in middle; punctures with seta extended above cuticle in dry specimens. Scintilla

distinct, flat, impunctate shelf with arcuate hind margin. Prosternum carinate, carina produced anteriorly as very short

spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and

external carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal

process relatively broad, sides parallel in apical 0.50, apex blunt, width at apex subequal distance separating internal

and median carinae. Metasternum lacking plaques. Small, cariniform tubercle just lateral to normal location of plaques

but on right side only, left side without tubercle. Elytra: Length 1.06 mm. Maximum width (at midlength) 0.66 mm.

Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures

round; intervals not elevated, width approximately equal to puncture diameter, as are interstices between adjacent

punctures of row; punctures each with seta. Explanate margin quite narrow, ended near posterior 0.20, with extremely

fine serrations near apices. Elytral apices, in dorsal aspect, slightly truncate; in posterior aspect, elytral margin elevated

obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly equilateral

triangle; posterior margin straight. Glabrous segments at apex moderately produced, arched markedly to venter.

Segment 7 emarginate at apex, and asymmetrical. Legs: Profemur with prominent cariniform tubercle on inner surface

at base. Protibia arcuate, expanded in apical 0.33, with prominent group of setae at base of enlargement. Mesotibia

flattened on inner surface in apical 0.33. Metatibia with lateral surface straight, medial surface slightly arcuate, widest

near apical 0.33. Genitalia: Aedeagus as illustrated (Fig. 38B)(1 examined).

Distribution. - (Fig. 167). Known only from type-locality near El Colegio in Cundinamarca,

Colombia.

Etymology. - Latin, scintilla (spark) plus bella (beautiful). This name refers to the

attractiveness of adults and their pronotal scintilla.

Remarks. - The holotype has a small, cariniform prominence on the metasternum just

lateral to the area usually occupied by plaques (but which are absent from adults of this

species). This cariniform prominence is present on the right side only. No other Western

Hemisphere Hydraena now known has such a metasternal modification.

28. Hydraena scintillutea new species

(Figs. 38A,167)

Type-locality. - Jaboticatubas, km 117, Serra do Cipo, Minas Gerais, Brazil.

Type-specimens. - The holotype male is deposited in MSP. One male paratype, with same

data, is deposited in USNM. These specimens were collected by Vanin and Froehlich, October

7, 1975.

Diagnosis. - Coarsely, densely punctate pronotum with a well demarcated, rectangular,

dark brown macula on the disc which is nicely highlighted by the surrounding testaceous

borders, plus a large scintilla serve to distinguish adults of H. scintillutea. The scintilla is very

apparent not only because of its large size, but also because its shiny surface contrasts with the

duller pronotum.

Description. — Form: Ovate. Size: Holotype 1.36 mm long, 0.58 mm wide. Color: Head black except maxillary

palpi and antennae testaceous. Pronotum with rectangular dark brown macula on disc, remainder testaceous. Elytra

Quaest. Ent., 1980, 16 (1,2)

Figs. 38A - D, Aedeagi of Hydraena holotypes. (A) H. scintillutea. (B) H. scintillabella. (C) H. alterra. (D) H. terralta.

Western Hemisphere Hydraenidae

121

brown. Venter dark brown. Legs, inflexed margin of pronotum and elytral epipleura testaceous. Head: Length 0.22 mm;

width 0.36 mm. Frons densely, closely punctate. Frontoclypeal suture slightly arcuate. Clypeus microreticulate,

moderately punctate. Labroclypeal suture straight. Labrum microreticulate, bilobed, median emargination ended at

midlength. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4 respectively: 0.20/0.09/0.16;

palpomere 4 asymmetrical, widest near midlength. Mentum wider than long, dull, microreticulate. Submentum

microreticulate. Genae shining, foveolate laterally; posterior ridge absent. Postgena microreticulate. Thorax: Pronotum

length at midline 0.32 mm; maximum width (slightly behind midlength) 0.48 mm; sides margined, denticulate,

moderately produced at middle, slightly arcuate and convergent to anterior angles, sinuate and convergent to posterior

angles; anterior border 0.40 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate

to rear in middle 0.50; posterior border 0.43 mm wide, slightly arcuate to rear. Posterointernal foveolae well developed,

punctation similar to that on disc. Posteroexternal foveolae slightly developed. Interfoveolar depression moderately

developed. Anteroexternal foveolae well developed, extended over slightly more than 0.25 width of anterior region of

pronotum. Transverse foveola not developed, punctures in this area closer together than those on disc. Disc dull, densely,

moderately coarsely punctate, punctures apparently without setae. Scintilla large, posterior margin markedly arcuate.

Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin carina; carina sinuate in

lateral view. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina

extended to base of intercoxal process; intercoxal process relatively narrow, apex blunt, width at apex 0.33 distance

between internal and median carinae. Metasternum with plaques narrow, slightly elevated, microreticulate, slightly

convergent anteriorly; plaques separated at base by three times plaque width; width of each plaque less than that of

intercoxal process. Elytra: Length 0.88 mm; maximum width (slightly behind midlength) 0.58 mm. Disc moderately

dull, with 10 rows of large punctures between suture and humeral callus, rows slightly irregular near suture in basal

0.25; intervals very narrow, zig-zag; interstices between punctures of row equally narrow. Explanate margin well

developed, ended near posterior 0.14, edge extremely finely serrate. Elytral apices, in dorsal aspect, slightly truncate; in

posterior aspect, elytral margin elevated obliquely toward suture, in form of slight angle with opposite elytron.

Abdomen: Intercoxal segment flat, nearly an equilateral triangle; posterior margin straight. Glabrous segments at apex

markedly produced, arched ventrad; sternum 6 with oval depression in middle; tergum 7 not emarginate at apex. Legs:

Profemur slightly excavate on inner surface in basal 0.50. Protibia slightly arcuate, inner surface expanded in apical

0.33. Other legs slender, unmodified. Genitalia: Aedeagus as illustrated (Fig. 38A)(2 examined).

Natural History. - The label notation, “riacho temporario” accompanies the specimens.

Distribution. - (Fig. 167). Presently known only from type-locality near Jaboticatubas in

the state of Minas Gerais, Brazil.

Etymology. - Latin, scintilla (spark) plus lutea (yellow). This name refers both to the well

developed scintilla and the distinctive testaceous borders of the pronotum which contrast

attractively with the black macula.

29. Hydraena alt err a new species

(Figs. 38C,167)

Type-locality. - Jaboticatubas, km 121, Serra do Cipo, Minas Gerais, Brazil.

Type-specimens. - The holotype male and allotype with identical data are deposited in

MSP. Paratypes (2 males, 2 females) are deposited in MSP, USNM and PDP. These

specimens were collected by Vanin and Froehlich, October 7, 1975.

Diagnosis. - Small size (1.28 mm long), dark color, absence of plaques, small scintilla, and

rather coarsely punctate pronotum serve to distinguish H. alterra from other Brazilian

members of the leechi group. The aedeagus should be studied to reliably distinguish males of

this species from those of H. terralta.

Description. — Form: Ovate. Size: Holotype 1.28 mm long, 0.56 mm wide. Color: Dorsum of head and pronotal

disc black, remainder brown. Head: Length 0.22 mm; width 0.34 mm. Frons closely, moderately coarsely punctate,

pubescence rather apparent. Frontoclypeal suture slightly arcuate. Clypeus microreticulate. Labroclypeal suture straight.

Labrum microreticulate, bilobed, median emargination ended at midlength. Maxillary palpus with following lengths (mm)

of palpomeres 2, 3 and 4 respectively: 0.22/0.08/0.14; palpomere 4 slightly asymmetrical, widest near midlength. Mentum

wider than long, microreticulate, punctulate. Submentum microreticulate. Genae shiny, foveolate laterally; posterior ridge

absent, Postgena microreticulate. Thorax: Pronotum length at midline 0.30 mm; Maximum width (slightly behind

midlength) 0.43 mm; sides margined, denticulate, moderately produced at middle, slightly arcuate and convergent to

anterior angles, slightly sinuate and convergent to posterior angles; anterior border 0.36 mm wide, straight and nearly

Quaest. Ent., 1980, 16 (1,2)

122

Perkins

perpendicular to midline in lateral 0.25, slightly arcuate to rear in middle 0.50; posterior border 0.40 mm wide, very

slightly arcuate to rear. Posterointernal foveolae moderately developed, punctate as disc. Posteroexternal foveolae

moderately developed. Interfoveolar depression moderately developed. Anteroexternal foveolae well developed, each

extended across 0.25 width of anterior region of pronotum. Transverse foveola shallow, densely punctate, punctures

closer together than those on disc. Disc dull, densely, moderately coarsely punctate, setae unapparent. Scintilla small,

very narrow. Prosternum carinate, thin carina between coxae. Mesosternum with internal and external carinae divergent

from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process narrow, apex blunt,

width at apex 0.50 distance between internal and median carinae. Metasternum without plaques. Elytra: Length

0.68 mm; maximum width (slightly past midlength) 0.56 mm. Disc dull, with 10 rows of large, deep punctures between

suture and humeral callus; intervals narrow, zig-zag; interstices between punctures of row equally narrow. Explanate

margin well developed, ended near posterior 0.14, finely serrate. Elytral apices rounded in dorsal view; in posterior

aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal

segment flat, nearly an equilateral triangle, posterior border straight. Glabrous segments at apex moderately produced.

Legs: Protibia very slightly excavate, widest near distal 0.20, not expanded. Other legs slender, unmodified. Genitalia:

Aedeagus as illustrated (Fig. 38C).(3 examined).

Natural History. - The label notation, “EM Leiothrix” accompanies the specimens.

Distribution. - (Fig. 167). Presently known only from the type-locality near Jaboticatubas

in the highlands of Minas Gerais, Brazil.

Etymology. - Latin, alta (high) plus terra (land). I refer to the highlands of Brazil, the

habitat of this species. The name alterra is also meant to symbolize the close relationship to H.

terralta, and the shorter word, alterra , serves as a reminder that adults of this species are

shorter in body length and aedeagal length than are those of terralta.

30. Hydraena terralta new species

(Figs. 38D,167)

Type-locality. - Jaboticatubas, km 121, Serra do Cipo, Minas Gerais, Brazil.

Type-specimen. - The holotype male (unique) is deposited in MSP. This specimen was

collected by Vanin and Froehlich, October 7, 1975.

Diagnosis. - The aedeagus should be studied to reliably distinguish members of this species

from those of H. alterra. H. alterra lacks plaques whereas the one specimen of H. terralta now

known has very small, oval plaques. The very small size of the plaques, however, suggests that

this feature may prove unreliable for identification purposes.

Description. — Form: Ovate. Size: Holotype 1.36 mm long, 0.58 mm wide. Color: Dorsum of head and pronotal

disc black, remainder brown. Head: Length 0.22 mm; width 0.34 mm. Frons closely, moderately coarsely punctate.

Frontoclypeal suture slightly arcuate. Clypeus microreticulate. Labroclypeal suture straight. Labrum microreticulate,

bilobed, median emargination ended at midlength. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4

respectively: 0.20/0.08/0.14; palpomere 4 slightly asymmetrical, widest near midlength. Mentum wider than long,

microreticulate, punctulate. Submentum microreticulate. Genae shiny, foveolate laterally; posterior ridge absent. Postgena

microreticulate. Thorax: Pronotum length at midline 0.32 mm; maximum width (at midlength) 0.45 mm; sides margined,

denticulate, moderately produced at middle, slightly arcuate and convergent to anterior angles, slightly sinuate and

convergent to posterior angles; anterior border 0.36 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

slightly arcuate to rear in middle 0.50; posterior border 0.40 mm wide, very slightly arcuate to rear. Posterointernal

foveolae moderately developed, punctate as disc. Posteroexternal foveolae moderately developed. Interfoveolar depression

moderately developed. Anteroexternal foveolae well developed, each occupying about 0.25 width of anterior region of

pronotum. Transverse foveola shallow, densely punctate, punctures closer together than those on disc. Disc dull, densely,

moderately coarsely punctate, setae unapparent. Scintilla small, very narrow. Prosternum carinate, thin carina between

coxae. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to

base of intercoxal process, intercoxal process narrow, apex blunt, width at apex 0.50 distance between internal and median

carinae. Metasternum with plaques very small, nearly indistinguishable ovals near hind margin. Elytra: Length 0.88 mm;

maximum width (near midlength) 0.58 mm. Disc dull, with 10 rows of large, deep punctures between suture and humeral

callus; intervals narrow, zig-zag; interstices between punctures of row equally narrow. Explanate margin well developed,

ended near posterior 0.14, finely serrate. Elytral apices rounded in dorsal view; in posterior aspect, elytral margin elevated

obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral

triangle, posterior border straight. Glabrous segments at apex moderately produced. Legs: Profemur with very small

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123

tubercle on inner surface near midlength. Protibia slightly excavate on inner surface in distal 0.25. Other legs slender,

unmodified. Genitalia: Aedeagus as illustrated (Fig. 38D)(1 examined).

Natural History. - The label notation, “EM Leiothrix ” accompanies the specimen.

Distribution. - (Fig. 167). Presently known only from the type-locality near Jaboticatubas

in the highlands of Minas Gerais, Brazil.

Etymology. - Latin, terra (land) plus alta (high). I refer to the highlands of Brazil, where

this species is found. The name terralta is also meant to symbolize the close relationship to H.

alterra, the putative sister-species. Additionally, since terralta is a longer word than alterra , it

serves as a reminder that adults of this species are longer in aedeagal and body length than are

those of H. alterra.

31. Hydraena pavicula new species

(Figs. 39A,167)

Type-locality. - Above Huinco, 8400 feet, Lima, Peru.

Type-specimen. - The holotype male (unique) is deposited in USNM. Harley P. Brown

collected this specimen, November 12, 1971.

Diagnosis. - Distinguished from other members of the leechi Group which have a well

developed scintilla by the markedly microreticulate lateral depressed areas of the pronotum and

the microreticulation in and surrounding the elytral punctures. Adults are uniformly dark

brown, nearly black on the dorsal surface, the legs and palpi being slightly lighter. The plaques

are small, indistinctive ovals at the posterior 0.20 of the metasternum. Males have the protibiae

expanded in the distal 0.50; the metatibiae are very slender, their greatest width being less than

that of the protibiae.

Description. — Form: Elongate. Size: Holotype 1.80 mm long, 0.76 mm wide. Color: Dorsal surface dark brown.

Maxillary palpi and antennae testaceous. Ventral surface dark brown except legs, elytral epipleurae and inflexed margin

of pronotum brown. Head: Length 0.24 mm. Width 0.42 mm. Frons microreticulate, punctation coarse, punctures

separated by 0.50 puncture diameter, or less; surface moderately dull. Frontoclypeal suture weakly arcuate to rear.

Clypeus finely microreticulate at sides, very shiny in middle. Labroclypeal suture arcuate in dorsal aspect. Labrum

bilobed, microreticulate, each lobe symmetrical arc; median emargination ended slightly above midlength of labrum.

Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.28/0.12/0.20; palpomere 2 bent

outward at approximately midlength; palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight in basal 0.33, arcuate in apical 0.66, median surface arcuate; palpomere 4 widest near apical 0.33. Mentum wider

than long, surface moderately shining, microreticulate. Submentum microreticulation similar to mentum. Genae shining;

lateral area of each gena with well developed foveola; posterior ridge slightly developed. Postgena with microreticulation

similar to that of submentum. Last five antennomeres pubescent. Eyes 0.20 interocular distance in width. Thorax:

Pronotum length at midline 0.42 mm; maximum width (at approximately midlength) 0.56 mm; sides margined,

denticulate; sides moderately produced at middle, slightly arcuate and convergent to anterior angle, sinuate and

convergent to posterior; anterior border 0.44 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

moderately arcuate to rear in middle 0.50; posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal foveolae

well developed; punctures in foveola closer together than those on disc, some confluent. Anteroexternal and posteroexternal

foveolae confluent, producing explanate sides of pronotum; microreticulation in this area well developed. Transversal

foveola moderately developed, punctures closer together than punctures on disc. Disc moderately dull, microreticulate,

punctures separated by one-two times puncture diameter, microreticulation extremely lightly impressed on interstices,

reflections interrupted; each puncture with distinctive seta extended above cuticle in dry specimens. Scintilla distinct, flat,

impunctate shelf with arcuate hind margin. Prosternum carinate, carina produced anteriorly as very short spine; coxae

separated by thin, median carina, latter sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively

broad, sides nearly parallel, apex blunt, width at apex 0.66 distance between internal and median carinae. Metasternum

with low ridge posterior to intercoxal process; plaques small ovals at posterior 0.20. Elytra: Length 1.18 mm. Maximum

width (at midlength) 0.76 mm. Surface dull, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures with irregular margins, microreticulate within punctures; surface uneven, reflections interrupted;

intervals not elevated, width slightly greater than puncture diameter, interstices between adjacent punctures of row

generally smaller; each puncture with seta. Explanate margin quite narrow, ended near posterior 0.20, with prominent

Quaest. Ent., 1980, 16 (1,2)

124

Perkins

serrations near anterior angles. Elytral apices, in dorsal aspect gradually rounded; in posterior aspect, elytral margin

elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than

long, posterior margin straight. Glabrous segments at apex moderately produced. Segment 7 with deep, oblique

meargination on left side near apex. Legs: Profemur with oblique carina on inner surface at base. Protibia enlarged on

inner surface in apical 0.50. Metatibia gradually enlarged from base to apex. Genitalia: Aedeagus as illustrated

(Fig. 39A)(1 examined).

Distribution. - (Fig. 167). Presently known only from the type-locality near Huinco in the

department of Lima, Peru.

Etymology. - Latin, pavicula (rammer). Named in reference to the ram-like appearance of

the aedeagus (lateral view).

32. Hydraena costiniceps new species

(Figs. 39B,167)

Type-locality. - Salta, Salta, Argentina.

Type-specimen. - The holotype male (unique) is deposited in USNM. Paul and Phyllis

Spangler collected this specimen, May 18, 1969.

Diagnosis. - Males of H. costiniceps are distinguished from those of other species which

have a pronotal scintilla by the unmodified legs, densely punctate pronotum, plaque shape and

aedeagal form (Fig. 39B). The pronotum is densely punctate, most punctures separated by less

than puncture diameter; the surface is relatively shiny, however, due to the very smooth, flat

interstices. The plaques are triangular, the anterior ends being ill-defined, not well demarcated.

Description. — Form: Elongate. Size: Holotype 1.60 mm long, 0.72 mm wide. Color: Head with dorsal surface and

labrum dark brown; maxillary palpi and antennae testaceous. Pronotum testaceous at anterior and posterior 0.25, dark

brown in center 0.50; sides slightly lighter than center. Elytra brown approximately midway in color between extremes of

pronotum. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head:

Length 0.20 mm. Width 0.40 mm. Frons moderately punctured, interstices equal to or slightly greater than puncture

diameter; setae quite distinctive; surface shining; posterior margin emarginate in midline to receive scintilla. Surface

posterior to emargination with transverse ridges. Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal

suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended

at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4,

respectively: 0.30/0.12/0.22; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not

especially expanded; palpomere 4 with lateral surface slightly expanded at apical 0.33, median surface arcuate;

palpomere 4 widest slightly past midlength. Mentum wider than long, surface moderately shining, microreticulate.

Submentum microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge nearly

imperceptible. Postgena with microreticulation slightly larger than that of submentum. Last five antennomeres pubescent.

Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width

(at approximately midlength) 0.54 mm; sides margined, denticulate; sides relatively weakly produced at middle, slightly

arcuate and slightly convergent to anterior angle, very slightly sinuate and slightly convergent to posterior; anterior border

0.44 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50;

posterior border 0.48 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in

foveola similar to those on disc. Posteroexternal foveola delimited by a very shallow depression with punctation somewhat

closer than that of disc. Interfoveolar depression absent. Area between external foveolae weakly elevated. Anteroexternal

foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior

region of pronotum. Transverse foveola not developed, punctures in this area somewhat closer together than punctures on

disc. Disc shining, punctures close together and fine, separated by less than puncture diameter to thin walls; punctures

each with distinctive seta extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate

anterior and posterior margins. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by

thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from

anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides

parallel, apex blunt, width 0.66 distance between internal and median carinae. Metasternum with plaques moderately

developed, triangular, median margins divergent moderately from posterior to anterior; plaques nearly 0.50 length of

metasternum in midline; width of each plaque at posterior 0.66 width of intercoxal process; plaques flat in cross section.

Elytra: Length 1.07 mm. Maximum width (at midlength) 0.72 mm. Surface shining, disc with 10 rows of punctures

between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately

equal to 0.66 puncture diameter, as are interstices between adjacent punctures of a row; punctures each with a seta.

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125

Figs. 39A - D, Aedeagi of Hydraena holotypes. (A) H. pavicula. (B) H. costiniceps. (C) H. zapatina. (D) H. colombiana.

Explanate margin quite narrow, ended near posterior 0.10, with extremely fine serrations near apices. Elytral apices, in

dorsal aspect, moderately truncate; in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle

with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin arcuate. Glabrous segments

at apex moderately produced. Apical segment semi-circular, slightly emarginate at apex. Legs: Without apparent

modification. Genitalia: Aedeagus as illustrated (Fig. 39B)(1 examined).

Distribution. - (Fig. 167). Presently known only from the type-locality, Salta, Argentina.

Etymology. - Latin, costa (ridge) plus ina (diminutive) plus ceps (head). I refer to the very

small ridges on the occipital region of the head, above which is the scintilla.

Quaest. Ent., 1980, 16 (1,2)

126

Perkins

33. Hydraena germaini d’Orchymont

(Fig. 167)

Hydraena germaini d’Orchymont, 1923:38. (holotype depository uncertain; type-locality: Cochabamba, Bolivia).

According to d’Orchymont (1923) the holotype is deposited in the Museum National

d’Histoire Naturelle, Paris. Through the courtesy of that institution I have received for study a

single female paratype from the type-locality. There is a distinct possibility that further search

may result in finding the holotype, consequently I am not designating a lectotype at this time.

Diagnosis. - Adults are very similar to those of H. costiniceps, differing primarily in less

dense pronotal punctation. A more definitive diagnosis must await discovery of males and

description of the aedeagus.

Description. — Form: Elongate. Size: Paratype female studied 1.64 mm long, 0.74 mm wide. Color: Head with

dorsal surface dark brown except almost black areas near eyes; labrum dark brown; maxillary palpi testaceous; antennae

testaceous. Pronotum testaceous except transverse, rectangular, brown (lighter than head) macula on disc approximately

0.20 mm long, 0.38 mm wide; macula at borders blended into surrounding testaceous areas. Elytra brownish, intermediate

in darkness between pronotal macula and pronotal lateral areas. Ventral surface dark brown except maxillae, legs, elytral

epipleura and inflexed margin of pronotum light brown. Head: Length 0.23 mm. Width 0.41 mm. Frons moderately

punctured, interstices equal to or slightly greater than puncture diameter; surface shining. Frontoclypeal suture arcuate to

rear. Clypeus microreticulate. Labroclypeal suture straight across middle when in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.29/0.1 1/0.21; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight in basal 0.33, arcuate in apical 0.66, median surface evenly, extremely slightly arcuate; palpomere 4 widest at

distal 0.33. Mentum wider than long, surface moderately shining, microreticulate. Submentum microreticulate. Genae

shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with microreticulation

slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance

in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately midlength) 0.56 mm; sides

margined, denticulate; sides relatively weakly produced at middle, slightly arcuate and slightly convergent to posterior;

anterior border 0.46 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in

middle 0.50; posterior border 0.54 mm wide, slightly arcuate to rear. Posterointernal foveolae slightly developed; punctures

in foveola slightly closer together than those on disc. Posteroexternal foveola delimited by very shallow depression with

punctation somewhat closer than that of disc. Interfoveolar depression absent. Anteroexternal foveolae well developed,

each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum.

Transverse foveola not developed, punctures in this area somewhat closer together than punctures on disc. Disc shining,

punctures fine and deeply impressed, separated by one-two times puncture diameter; most punctures with distinctive seta

extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin. Prosternum

carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in

lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina

extended to base of intercoxal process; intercoxal process relatively narrow, sides nearly parallel, apex blunt, width at apex

0.66 distance between internal and median carinae. Metasternum with plaques well developed, straight, parallel, tapered

from posterior to anterior; plaques 0.50 length of metasternum in midline; greatest width of each plaque subequal to width

of intercoxal process at its midlength; plaques separated posteriorly by twice plaque width; plaques separated anteriorly by

approximately six times plaque width; plaques flat in cross section. Elytra: Length 1 .06 mm. Maximum width (at

midlength) 0.74 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width approximately equal to 0.66 puncture diameter, interstices

between adjacent punctures of row generally smaller; each puncture with seta. Explanate margin quite narrow, ended near

posterior 0.20, with serrations near anterior angles and in posterior 0.33. Elytral apices, in dorsal aspect, truncate; in

posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen:

Intercoxal segment flat, wider than long, posterior margin arcuate. Legs: Protibia weakly arcuate in apical 0.50. Genitalia:

Male unknown.

Distribution. - (Fig. 167). Presently known only from the type-locality, Cochabamba,

Bolivia.

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127

34. Hydraena colombiana new species

(Figs. 39D,167)

Type-locality. - 1 1 km. N. Bogota, Cundinamarca, Colombia.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. Paratypes with same data are in USNM(2) and PDP(2). These specimens were

collected by Paul and Phyllis Spangler, March 1-8, 1969.

Diagnosis. - Plaques are narrow, slightly arcuate, tapered to an acute apex anteriorly;

basally they are separated by about four times the width of a plaque. Males have the pronotal

scintilla slightly developed, the legs lacking modifications. The scintilla of females is extremely

narrow, nearly imperceptible. The aedeagus (Fig. 39D) is very distinctive.

Description. — Form: Elongate. Size: The holotype is 1.60 mm long, 0.64 mm wide. Color: Head with dorsal

surface dark brown; labrum dark brown; maxillary palpi brown; antennae brown. Pronotum brown at anterior and

posterior 0.25, dark brown in center 0.50. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and

inflexed margin of pronotum brown. Head: Length 0.20 mm. Width 0.38 mm. Frons moderately punctured, interstices

equal to or slightly greater than puncture diameter; surface shining, posterior margin emarginate to receive scintilla.

Frontoclypeal suture straight. Clypeus microreticulate at sides, sparsely in midline. Labroclypeal suture arcuate in dorsal

aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at approximately

midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.26/0.10/0.20; palpomere 2 bent outward at approximately midlength; apices palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface nearly straight in basal 0.33, arcuate in apical 0.66, median surface evenly,

extremely slightly arcuate; palpomere 4 widest near midlength. Mentum wider than long, surface moderately shining,

finely microreticulate. Submentum microreticulate. Genae moderately shining; lateral area of each gena with well

developed foveola; posterior ridge nearly imperceptible. Postgena with punctation slightly larger than that of submentum.

Last five antennomeres pubescent. Eyes slightly less than 0.20 interocular distance in width. Thorax: Pronotum length at

midline 0.38 mm; maximum width (at approximately midlength) 0.52 mm; sides margined, denticulate; sides relatively

slightly produced at middle, slightly arcuate and slightly convergent to anterior angle, very slightly sinuate and slightly

convergent to posterior; anterior border 0.42 mm wide, straight and nearly perpendicular to midline in lateral 0.25;

moderately arcuate to rear in middle 0.50; posterior border 0.48 mm wide, slightly arcuate to rear. Posterointernal foveolae

weakly developed; punctures in foveola somewhat closer together than those on disc. Posteroexternal foveola delimited by

very shallow depression with punctation somewhat closer than that of disc. Interfoveolar depression shallow and broad.

Area between foveolae not elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped,

extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures

in this area somewhat closer together than punctures on disc. Disc shining, punctures fine, separated by 0.50 puncture

diameter near anterior and posterior borders by puncture diameter in middle; punctures each with distinctive seta extended

above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin. Prosternum carinate,

carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to base of

intercoxal process; intercoxal process relatively narrow, sides nearly parallel, apex rounded, width slightly less than 0.50

distance between internal and median carinae. Metasternum with plaques well developed, slightly arcuate, triangular,

converging strongly from posterior to anterior; plaques 0.50 length of metasternum in midline; greatest width of each

plaque subequal to width of intercoxal process at its midlength; plaques separated posteriorly by approximately four times

greatest width of a plaque; plaques separated anteriorly by twice plaque width; plaques flat in cross section. Elytra: Length

1.06mm. Maximum width (at midlength) 0.64 mm. Surface shining, disc with 10 rows of punctures between suture and

humeral callus, some rows quite irregular, some punctures random at most anterior, most punctures round; intervals not

elevated, width approximately equal to puncture diameter, as are interstices between adjacent punctures of a row;

punctures each with a seta. Explanate margin quite narrow, ended near posterior 0.20, with extremely fine serrations near

apices. Elytral apices, in dorsal aspect, slightly truncate; in posterior aspect, elytral margin elevated obliquely toward

suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin

straight. Glabrous segments at apex moderately produced. Segment 7 emarginate at apex. Legs: Without apparent

modification. Genitalia: Aedeagus as illustrated (Fig. 39D)(3 examined).

Distribution. - (Fig. 167). Presently known only from the type-locality near Bogota,

Colombia.

Etymology. - Latin, colombiana , in reference to the geographical distribution.

Quaest. Ent., 1980, 16 (1,2)

128

Perkins

35. Hydraena paraguayensis Janssens

(Fig. 167)

Hydraena paraguayensis Janssens, 1972:259 (lectotype female deposited in 1SNB, here designated; type-locality: Acaray

waterfall, Puerto Presidente Stroessner, Alto Parana, Paraguay).

Diagnosis. - Among the South American species of the leechi group whose adults possess a

pronotal scintilla, H. paraguayensis adults are distinguished by the prosternum, which has a

small shelf between the procoxae and the median carina. Males are not yet known for this

species.

Description. — Form: Elongate-oval. Size: Lectotype 1.40 mm long, 0.62 mm wide. Color: Head with dorsal

surface dark brown; labrum brown; maxillary palpi and antennae testaceous. Pronotum light brown except macula

extended as transverse band from side to side from anterior 0.42 to posterior 0.14, macula lighter at margins. Elytra

midway in color between lighter and darker areas of pronotum. Ventral surface dark brown except legs, elytral epipleura

and inflexed margin of pronotum, brown. Head: Length 0.24 mm. Width 0.36 mm. Frons moderately punctured,

interstices equal to or slightly less than puncture diameter; surface moderately shining. Frontoclypeal suture straight.

Clypeus microreticulate. Labroclypeal suture slightly arcuate when in dorsal aspect. Labrum bilobed, microreticulate,

each lobe asymmetrical arc; median emargination ended slightly above midlength of labrum. Maxillary palpus with

following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.24/0.08/0.16; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight in basal 0.33, arcuate in apical 0.66, median surface arcuate; apical segment widest near distal 0.33. Mentum

nearly quadrangular, surface shining, finely and sparsely punctulate. Submentum microreticulate. Genae shining; lateral

area of each gena with well developed foveola; posterior ridge absent. Postgena with microreticulation slightly larger than

that of submentum. Last five antennomeres pubescent. Eyes 0.16 interocular distance in width. Thorax: Pronotum length

at midline 0.32 mm; maximum width (at approximately midlength) 0.48 mm; sides margined, denticulate; sides

moderately produced at middle, slightly arcuate and slightly convergent to anterior angle, sinuate and convergent to

posterior; anterior border 0.40 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate

to rear in middle 0.50; posterior border 0.44 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately

developed; punctures in foveola similar to those on disc. Posteroexternal foveola delimited by very shallow depression with

punctation somewhat closer than that of disc. Interfoveolar depression very slightly developed. Area between external

foveolae not elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across

slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area

somewhat closer together than punctures on disc. Disc shining, punctures fine, separated by puncture diameter near

anterior and posterior borders, and by twice puncture diameter in middle; most punctures with seta extended above cuticle

in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin. Prosternum carinate, carina produced

anteriorly into short spine; coxae separated from median carina by thin shelf; carina sinuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to base of

intercoxal process; intercoxal process relatively broad, sides nearly parallel, apex blunt, width at apex equal distance

between internal and median carinae. Metasternum with plaques moderately developed, straight, convergent moderately

from posterior to anterior; each plaque subtriangular, widest at base; plaques 0.43 length of metasternum in midline;

greatest width of each plaque 0.33 width of intercoxal process at its midlength; plaques separated posteriorly by

approximately three times plaque width; plaques flat in cross section. Elytra: length 0.88 mm. Maximum width (at

midlength) 0.62 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width approximately equal to puncture diameter, as are interstices

between adjacent punctures of row; each puncture without seta. Explanate margin quite narrow, ended near posterior 0.20,

with extremely fine, well separated serrations along entire margin; serrations somewhat closer near apices. Elytral apices,

in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle

with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Legs: Protibia very

slightly arcuate; other legs without apparent modification. Genitalia: Males unknown.

Distribution. - (Fig. 167). Known only from the type-locality near Puerto Presidente

Stroessner in the Department of Alto Parana, Paraguay.

Remarks. - The holotype and two paratypes of H. paraguayensis were requested from the

Institut royal des Sciences Naturelles de Belgique (through E. Janssens). When the shipping

box arrived, however, it was found to contain the pin with holotype label and locality labels, but

the specimen was no longer glued to the card. A search of the box proved fruitless. Therefore,

one of the paratypes was selected to serve as the lectotype, and is herein so designated.

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129

36. Hydraena plaumanni d’Orchymont

(Fig. 167)

Hydraena plaumanni d’Orchymont, 1937:457. (holotype female in 1SNB; type-locality: Nova Teutonia, Santa Catarina,

Brazil).

Diagnosis. - Distinguished from other Brazilian members of the leechi Group which have a

pronotal scintilla by form of the metasternal plaques, which are arcuate and separated

posteriorly by three times the width of a plaque. Males are not yet known for this species.

Description. — Form: Elongate. Size: Holotype 1.44 mm long, 0.56 mm wide. Color: Head with dorsal surface and

labrum dark brown; maxillary palpi and antennae testaceous. Pronotum testaceous except for transverse, rectangular,

brown (lighter than head) macula on disc approximately 0.10 mm long, 0.30 mm wide; macula at anterior and posterior

borders abruptly disappearing, at sides blended into surrounding testaceous areas. Elytra same color as pronotal macula.

Ventral surface dark brown except maxillae, legs, plaques, elytral epipleura and inflexed margin of pronotum testaceous.

Head: Length 0.20 mm. Width 0.35 mm. Frons coarsely punctured, interstices less than puncture diameter; surface dull.

Frontoclypeal suture straight. Clypeus finely punctulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.26/0.08/0.20; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight, medial surface arcuate, widest slightly past midlength. Mentum wider than long, surface shining, punctures fine,

sparse. Submentum microreticulate. Genae moderately shining, punctulate; lateral area of each gena with well developed

foveola; posterior ridge absent. Postgena with microreticulation similar to that of submentum. Last five

antennomeres pubescent. Eyes 0.17 interocular distance in width. Thorax: Pronotum length at midline 0.34 mm;

maximum width (at approximately midlength) 0.47 mm; sides margined, denticulate; sides relatively weakly produced at

middle, slightly arcuate and slightly convergent to anterior angle, slightly sinuate and slightly convergent to posterior;

anterior border 0.39 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in

middle 0.50; posterior border 0.42 mm wide, slightly arcuate to rear. Posterointernal foveolae very slightly developed;

punctures in foveola closer together than those on disc. Posteroexternal foveola delimited by very shallow depression with

punctation somewhat closer than that of disc. Interfoveolar depression absent. Area between external foveolae flat.

Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33

width of anterior region of pronotum. Transverse foveola not developed, although punctures in this area are somewhat

closer together than punctures on disc. Disc moderately shining, punctures fine and deeply impressed, separated by narrow

walls near anterior and posterior borders, and by 0.5- 1.0 times puncture diameter in middle; most punctures with seta

extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin. Prosternum

carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in

lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina

extended to base of intercoxal process; intercoxal process relatively narrow, sides nearly parallel, apex blunt, width at apex

0.50 distance between internal and median carinae. Metasternum with plaques well developed, slightly arcuate, with

concave side toward midline; 0.50 length of metasternum in midline; greatest width of each plaque subequal to width of

intercoxal process at its midlength; plaques separated posteriorly by approximately twice plaque width; plaques separated

anteriorly by basal width of a plaque; plaques flat in cross section. Elytra: Length 0.92 mm. Maximum width (at

midlength) 0.60 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width 0.50 puncture diameter, as are interstices between adjacent

punctures of row; each puncture with seta. Explanate margin quite narrow, ended near posterior 0.20, with extremely fine,

well separated serrations along entire margin; serrations somewhat closer near apices. Elytral apices, in dorsal aspect,

gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite

elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous segments at apex

moderately produced. Legs: Without apparent modification. Genitalia: Males unknown.

Distribution. - (Fig. 167). Known only from the type-locality at Nova Teutonia in the state

of Santa Catarina, Brazil.

Remarks. - The holotype is the only specimen I have studied.

37. Hydraena sordida Sharp

(Fig. 167)

Hydraena sordida Sharp, 1882:94 (lectotype female in BMNH, here designated; type-locality: San Joaquin, Baja

Verapaz, Guatemala).

Quaest. Ent., 1980, 16 (1,2)

130

Perkins

Diagnosis. - The finely, densely punctate pronotum with its well developed scintilla, plus

shape of plaques, which are reduced to small ovals at the posterior 0.20 of the metasternum,

must serve as the characteristics, albeit rather unsatisfactory, to distinguish H. sordida adults.

A more complete diagnosis must await discovery of males.

Description. — Form: Elongate. Size: Lectotype 1 .67 mm long, 0.74 mm wide. Color: Head with dorsal surface

brown; labrum brown; maxillary palpi brown; antennae testaceous. Pronotum brown, lighter toward lateral areas. Elytra

brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length

0.24 mm. Width 0.42 mm. Frons moderately punctured, most interstices less than puncture diameter; surface moderately

shining. Frontoclypeal suture arcuate to rear. Clypeus microreticulate. Labroclypeal suture arcuate in dorsal aspect.

Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of

labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.28/0.11/0.19;

palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4

with lateral surface nearly straight, medial surface arcuate, widest near midlength. Mentum wider than long, surface

moderately shining, microreticulate. Submentum microreticulation similar to mentum. Genae shining; lateral area of each

gena with well developed foveola; posterior ridge absent. Postgena with microreticulation slightly larger than that of

submentum. Last five antennomeres pubescent. Eyes slightly less than 0.17 interocular distance in width. Thorax:

Pronotum length at midline 0.40 mm; maximum width (at approximately midlength) 0.57 mm; sides margined,

denticulate; sides moderately produced at middle, slightly arcuate and convergent to anterior angle, sinuate and

convergent to posterior; anterior border 0.46 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

moderately arcuate to rear in middle 0.50; posterior border 0.46 mm wide, slightly arcuate to rear. Posterointernal foveolae

well developed; punctures in foveola closer together than those on disc. Posteroexternal foveola well developed.

Interfoveolar depression well developed, disc elevated. Area between external foveolae elevated. Anteroexternal foveolae

well developed, each foveola somewhat crescent shaped, occupying slightly less than 0.33 width of anterior region of

pronotum. Transverse foveola slightly developed, punctures closer together than punctures on disc. Disc moderately dull,

punctures fine, deeply impressed, separated by puncture diameter to nearly confluent; most punctures with seta extended

above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin. Prosternum carinate,

carina produced anteriorly into very short spine; coxae separated by thin, median carina; carina sinuate line in lateral

aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to

base of intercoxal process; intercoxal process relatively broad, sides nearly parallel; apex blunt, width at apex nearly 0.66

distance between internal and median carinae. Metasternum with plaques very small ovals at posterior 0.20. Elytra:

Length 1.07 mm. Maximum width (at midlength) 0.74 mm. Surface shining, disc with 10 rows of punctures between

suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal to

0.50 puncture diameter, as are interstices between adjacent punctures of a row; each puncture with a seta. Explanate

margin quite narrow, ended near posterior 0.14, with extremely fine, well separated serrations along entire margin;

serrations slightly closer near apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin

elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than

long, posterior margin straight. Legs: Protibiae very slightly arcuate; other legs without apparent modification. Genitalia:

Males unknown.

Distribution. - (Fig. 167). Baja Verapaz, Guatemala.

Remarks. - Other than the lectotype I have seen only four females, two from the

type-locality, and two from San Geronimo. These four specimens are herein designated

paralectotypes.

38. Hydraena puncticollis Sharp

(Fig. 167)

Hydraena puncticollis Sharp, 1882:93 (lectoype female in BMNH, here designated; type-locality: Paso Antonio, 400 feet,

Guatemala).

Diagnosis. - Small size (1.46 mm long), coarse pronotal punctation, and elytral apices,

which do not form an angle with one another in posterior aspect, serve as the diagnostic

features available at this time. Males are unknown. Refer to the remarks section for futher

comments.

Description. — Form: Elongate-oval. Size: Lectotype 1.46 mm long, 0.66 mm wide. Color: Head with dorsal

surface and labrum dark brown; maxillary palpi and antennae brown. Pronotum dark brown except for transverse,

rectangular, black macula on disc approximately 0.16 mm long, 0.34 mm wide; macula at borders blended into

surrounding brownish areas. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin

Western Hemisphere Hydraenidae

131

of pronotum, brown. Head: Length 0.19 mm. Width 0.35 mm. Frons coarsely punctured, interstices less than puncture

diameter; surface shining. Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture arcuate when

viewed from above. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4,

respectively: 0.26/0.10/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not

especially expanded; palpomere 4 with lateral surface nearly straight; median surface evenly, extremely slightly arcuate;

palpomere 4 widest slightly past midlength. Mentum longer than wide, surface moderately shining, finely punctulate.

Submentum evenly, finely microreticulate. Genae shining; lateral area of each gena with well developed foveola;

posterior ridge absent. Postgena with microreticulation slightly larger than that of submentum. Last five

antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at midline

0.35 mm; maximum width (at approximately midlength) 0.48 mm; sides margined, denticulate; sides moderately

produced at middle, slightly arcuate and slightly convergent to anterior angle, arcuate and slightly convergent to

posterior; anterior border 0.40 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately

arcuate to rear in middle 0.50; posterior border 0.44 mm wide, slightly arcuate to rear. Posterointernal foveolae well

developed; punctures in foveola similar to those on disc. Posteroexternal foveola delimited by very shallow depression

with punctation somewhat closer than that of disc. Anteroexternal foveolae well developed, each foveola somewhat

crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not

developed, punctures in this area somewhat closer together than punctures on disc. Disc shining, punctures fine,

separated by puncture diameter; each puncture with seta extended above cuticle in dry specimens. Scintilla distinct, flat,

impunctate shelf with arcuate hind margin. Prosternum carinate, carina produced anteriorly as very short spine; coxae

separated by thin median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively

narrow, sides nearly parallel, apex blunt, width at apex 0.50 distance between internal and median carinae.

Metasternum with plaques well developed, slightly arcuate, convergent moderately from posterior to anterior; plaques

separated posteriorly by approximately three times plaque width; plaques separated anteriorly by plaque width; plaques

slightly rounded in cross section. Elytra: Length 0.92 mm. Maximum width (at midlength) 0.68 mm. Surface shining,

disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures round; intervals

not elevated, width approximately equal to puncture diameter, as are interstices between adjacent punctures of a row;

each puncture with a seta. Explanate margin quite narrow, ended near posterior 0.10, with extremely fine, well

separated serrations along entire margin; serrations somewhat closer near apices. Elytral apices, in dorsal aspect,

gradually rounded; in posterior aspect, elytral margin does not elevate obliquely toward suture, not in form of angle

with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle, posterior margin straight.

Glabrous segments at apex moderately produced. Segment 7 emarginate at apex. Legs: Protibia slightly concave on

inner surface. Other legs without apparent modification. Genitalia: Males unknown.

Distribution. - (Fig. 167). Guatemala.

Remarks. - Among specimens I collected in the summer of 1974 are more than 200

Hydraena from various localities in Guatemala, Honduras and Mexico, some of which I believe

may be conspecific with H. puncticollis. Although these specimens make up series from many

localities and several different types of streams, all of the series include females only. Further

study is necessary to determine whether absence of males is a sampling artifact or a result of

parthenogenesis. These specimens appear to represent more than one species, based upon

pronotal sculpture and body size, but without males I am unwilling to assign any of them to H.

puncticollis or to describe them as new. A more precise diagnosis of H. puncticollis must await

further material.

39. Hydraena zapatina new species

(Figs. 39C,167)

Type-locality. - Seven miles S. Mazamitla, Jalisco, Mexico.

Type-specimens. - The holotype male and allotype with identical data are deposited in

USNM. My wife Maureen and I collected these specimens, August 15, 1974.

Diagnosis. - Combination of absence of a pronotal scintilla and random (non-serial)

punctures on the elytral disc serve as diagnostic features for this species. The dorsal surface is

very shiny, the pronotum being sparsely punctate and with a dark brown fascia which contrasts

Quaest. Ent., 1980, 16 (1,2)

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well with the surrounding testaceous area. The plaques are well developed, convergent slightly

anteriorly, separated at their bases by about plaque width; each plaque is about 0.50 the length

of the metasternum and as wide as the mesosternal process. The metatibiae of males are

expanded, but very slightly so, at midlength to form a small point, then tapered to the apex to

form a slight indentation; within the indentation there are some stiff spines which contact the

leg.

Description. — Form: Elongate. Size: Holotype 1.46 mm long, 0.62 mm wide. Color: Head with dorsal surface dark

brown; labrum testaceous; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and posterior

0.25, dark brown in middle 0.50. Elytra brown. Ventral surface dark brown except legs, elytral epipleura, mentum and

inflexed margin of pronotum testaceous. Head: Length 0.20 mm. Width 0.34 mm. Frons moderately punctured, interstices

equal to or slightly greater than puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus finely

microreticulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc;

median emargination ended slightly above midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.24/0.12/0.20; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface slightly arcuate, median surface evenly

arcuate; palpomere 4 widest near midlength. Mentum wider than long, surface shining, finely punctulate. Submentum

microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with

microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes 0.25 interocular

distance in width. Thorax: Pronotum length at midline 0.32 mm; maximum width (at approximately midlength) 0.44 mm;

sides margined, denticulate; sides moderately produced at middle, slightly sinuate and convergent to anterior angle,

sinuate and convergent to posterior; anterior border 0.36 mm wide, straight and nearly perpendicular to midline in lateral

0.25, moderately arcuate to rear in middle 0.50; posterior border 0.38 mm wide, slightly arcuate to rear. Posterointernal

foveolae moderately developed; punctures in foveola similar to those on disc. Posteroexternal foveola delimited by very

shallow depression with punctation somewhat closer than that of disc. Interfoveolar depression moderately developed. Area

between external foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent

shaped, extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed,

punctures in this area somewhat closer together than punctures on disc. Disc shining, punctures fine, separated by two to

four times puncture diameter; each puncture with distinctive seta which extended cuticle in dry specimens. Scintilla

absent, although this region very shiny. Prosternum carinate, carina produced anteriorly as very short spine; coxae

separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively

broad, sides nearly parallel, apex blunt, width at apex 0.66 distance between internal and median carinae. Metasternum

with plaques well developed, straight, convergent moderately from posterior to anterior; plaques 0.50 length of

metasternum in midline; width of each plaque subequal to width of intercoxal process; plaques separated posteriorly by

slightly less than plaque width; plaques flat in cross section. Elytra: Length 0.88 mm. Maximum width (at midlength)

0.64 mm. Surface shining, disc with punctures somewhat serial near suture, randomly arranged on most of disc; most

punctures separated by puncture diameter; punctures each with seta. Explanate margin quite narrow, ended near posterior

0.20. with extremely fine serrations near anterior angles. Elytral apices, in dorsal aspect, gradually rounded; in posterior

aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal

segment flat, longer than wide, posterior margin straight. Glabrous segments at apex moderately produced. Segment 7

slightly emarginate at apex. Legs: Protibia slightly expanded on inner surface near midlength. Metatibiae gradually

enlarged from base to midlength, then gradually tapered to apex, hence widest at midlength; posterior 0.50 with small stiff

spines on inner surface in contact with leg. Genitalia: Aedeagus as illustrated (Fig. 39C)(1 examined).

Natural History. - Refer to H. scopula.

Distribution. - (Fig. 167). Presently known only from the type-locality near Mazamitla in

the state of Jalisco, Mexico.

Etymology. - zapatina , from Spanish in reference to the shoe-shaped process of the

aedeagus (lateral view).

40. Hydraena campbelli new species

(Figs. 37B,167)

Type-locality. - Junction of highways 190 and 195, Chiapas, Mexico.

Type-specimens. - The holotype male and allotype with identical data are deposited in

CNC. J. M. Campbell collected these specimens, June 11, 1969. Paratypes from the same

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133

locality are deposited in CNC (12), USNM (2) and PDP (2).

Diagnosis. - The only totally satisfactory characteristic to distinguish males of this species is

aedeagal form (Fig. 37B), which is quite singular. H. campbelli adults are moderately small,

about 1.45 mm long, with well developed scintilla in both sexes, and males lack a metatibial

brush of hairs. The plaques are oval, occupy about the posterior 0.33 of the metasternum, and

are very slightly convergent anteriorly.

Description. — Form: Elongate. Size: Holotype 1.44 mm long, 0.64 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and posterior

0.25, dark brown in middle 0.50; sides lighter than middle, Elytra brown. Ventral surface dark brown except legs, elytral

epipleura, mentum and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width 0.38 mm. Frons moderately

punctured, interstices equal to or slightly greater than puncture diameter; surface moderately shining; posterior margin

weakly emarginate to receive scintilla. Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture arcuate

when viewed from above. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.26/0.10/0.16; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface nearly straight in basal 0.33, arcuate in apical 0.66, median surface evenly,

slightly arcuate; palpomere 4 widest slightly past midlength. Mentum wider than long, surface moderately shining, finely

punctulate. Submentum microreticulate. Genae moderately shining; lateral area of each gena with well developed foveola;

posterior ridge nearly imperceptible. Postgena with microreticulation slightly larger than that of submentum. Last five

antennomeres pubescent. Eyes slightly greater than 0.20 interocular distance in width. Thorax: Pronotum length at

midline 0.36 mm; maximum width (at approximately midlength) 0.52 mm; sides margined, denticulate; sides moderately

produced at middle, slightly arcuate and slightly convergent to anterior angle, sinuate and moderately convergent to

posterior; anterior border 0.42 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate

to rear in middle 0.50; posterior border 0.44 mm wide, slightly arcuate to rear. Posterointernal foveolae very slightly

developed; punctures in foveola somewhat closer together than those on disc. Posteroexternal foveola delimited by very

shallow depression with punctation somewhat closer than that of disc. Interfoveolar depression slightly developed. Area

between external foveolae rather noticeably elevated. Anteroexternal foveolae well developed, each foveola somewhat

crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not

developed, punctures in this area somewhat closer together than punctures on disc. Disc moderately shining, punctures

separated by thin walls near anterior and posterior borders, by 0.50 puncture diameter in middle; punctures without

distinctive seta extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate hind margin.

Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina

sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median

carina extended to base of intercoxal process; intercoxal process relatively narrow, sides nearly parallel, apex round, width

nearly 0.50 distance between internal and median carinae. Metasternum with plaques moderately developed, somewhat

oval, convergent moderately from posterior to anterior; plaques 0.33 length of metasternum in midline; greatest width of

each plaque slightly less than width of intercoxal process at its midlength; plaques separated posteriorly by approximately

twice plaque width; plaques flat in cross section. Elytra: Length 0.98 mm. Maximum width (at midlength) 0.64 mm.

Surface moderately shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most

punctures round; intervals not elevated, width approximately 0.50 puncture diameter, as are interstices between adjacent

punctures of a row; most punctures with a seta. Explanate margin quite narrow, ended near posterior 0.20, with fine

serrations near anterior angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral

margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly

an equilateral triangle, posterior margin arcuate. Glabrous segments at apex moderately produced. Segment 7 without

emargination at apex. Legs: Protibia slightly arcuate. Metatibia very slightly arcuate. Genitalia: Aedeagus as illustrate

(Fig. 37B)(4 examined).

Distribution. - (Fig. 167). Known only from the type-locality in the mountains of Chiapas,

Mexico.

Etymology. - I am pleased to dedicate this species to J. M. Campbell, who collected the only

known specimens.

41. Hydraena exilipes new species

(Figs. 41D, 167)

Type-locality. - Two miles SW Ciudad Victoria, Tamaulipas, Mexico.

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Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. These specimens plus two male and three female paratypes (PDP) from the same

locality were collected by my wife Maureen and I, July 27, 1974.

Diagnosis. - Distinguished from adults of other species of the leechi Group, which also lack

a scintilla and do not have the anteromedian region of the metasternum elevated, by the small,

oval plaques. The plaques are widely separated, the distance being about equal to four times the

width of a plaque. The pronotum is distinctively produced at the sides, being nearly equally

convergent to the anterior and posterior angles. The legs are exceptionally long and slender.

Description. — Form: Elongate. Size: Holotype 1.74 mm long, 0.74 mm wide. Color: Dorsal surface dark brown,

except border of pronotum slightly lighter; maxillary palpi brown; antennae brown. Ventral surface dark brown except

legs; elytral epipleura, mentum and inflexed margin of pronotum brown. Head: Length 0.24 mm. Width 0.40 mm. Frons

moderately punctured, interstices equal to or slightly less than puncture diameter; setae quite prominent; surface dull.

Clypeus microreticulate. Labroclypeal suture nearly straight across middle in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.30/0.14/0.20; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight, median surface arcuate; palpomere 4 widest slightly past midlength. Mentum wider than long, surface dull,

microreticulate. Submentum microreticulate. Genae moderately shining; lateral area of each gena with well developed

foveola; posterior ridge moderately developed at sides, absent from midline. Postgena with microreticulation slightly

smaller than that of submentum. Last five antennomeres pubescent. Eyes 0.50 interocular distance in width. Thorax:

Pronotum length at midline 0.40 mm; maximum width (at approximately midlength) 0.58 mm; sides margined,

denticulate; sides rather markedly produced at middle, slightly arcuate and markedly convergent to anterior angle, sinuate

and convergent to posterior; anterior border 0.42 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

moderately arcuate to rear in middle 0.50; posterior border 0.48 mm wide, slightly arcuate to rear. Posterointernal foveolae

well developed; punctures in foveola similar to those on disc. Posteroexternal foveola well developed. Interfoveolar

depression slightly developed. Area between external foveolae slightly elevated. Anteroexternal foveolae well developed,

each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum.

Transverse foveola slightly developed, with punctures separated by thin walls. Disc dull, punctures moderately large,

generally separated by puncture diameter or less; each puncture with very distinctive seta extended above cuticle in dry

specimens. Scintilla apparently absent; thin, much longer than wide, transparent shelf present in this region, but posterior

margin indistinctly defined. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin,

median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from

anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides

nearly parallel, apex blunt, width at apex 0.66 distance between internal and median carinae. Metasternum with plaques

weakly developed, oval in shape, approximately three times as long as wide, located at posterior 0.17, convergent

moderately from posterior to anterior; plaques 0.17 length of metasternum in midline; plaques separated by about four

times plaque width; plaques flat in cross section. Elytra: Length 1.14 mm. Maximum width (at midlength) 0.74 mm.

Surface dull, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures round;

intervals not elevated, width approximately equal to 0.50 puncture diameter, as are interstices between adjacent punctures

of a row; each puncture with a distinctive seta. Explanate margin rather well developed, ended near apices, with serrations

near anterior angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin not

elevated obliquely toward suture, not in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than

long, posterior margin weakly arcuate. Glabrous segments at apex moderately produced. Segment 7 somewhat conical;

apex slightly emarginate. Legs: Profemur with tubercle on inner surface near basal 0.33. Protibia expanded on inner

surface near apical 0.33, lateral surface straight. Metafemur relatively thin. Metatibia straight, gradually enlarged from

base to apex, relatively long and thin. Genitalia: Aedeagus as illustrated (Fig. 41D)(3 examined).

Natural History. - These beetles were collected at the sand-gravel margin of a semi-arid

stream. Limnebius angustulus adults were also found at this locality.

Distribution. - (Fig. 167). Presently known only from the type-locality near Ciudad Victoria

in the state of Tamaulipas, Mexico.

Etymology. - Latin, exilis (thin) plus ipes (foot). This species has very slender legs.

Western Hemisphere Hydraenidae

135

Figs. 40A - F, Hydraena ozarkensis. (A) head of <3, dorsal aspect. (B) head of 9, dorsal aspect. (C) occipital ridges of 6.

(D) 6 pronotum. (E) metasternum. (F) prosternum and venter of head.

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42. Hydraena ozarkensis new species

(Figs. 40A-F,41 A-B,42B, 1 67)

Type-locality. - Rush Creek, 2 miles E. Jane, McDonald Co., Missouri.

Type-specimens. - The holotype male and allotype with same locality data are deposited in

USNM. I collected these specimens, August 8, 1972. Paratypes (61) are listed in the appendix.

Diagnosis. - Random, non-serial arrangement of punctures on the elytral disc plus small

size, about 1.36 mm long, serve to readily distinguish H. ozarkensis adults from all other

members of the leechi Group which have a pronotal scintilla, except H. maureenae. From this

latter species H. ozarkensis is distinguished by broader form (with the sides of the elytra being

rounded, not parallel), distribution (Fig. 42B), and aedeagus (Figs. 41 A-C).

Description. — Form: Elongate-oval. Size: Holotype 1.36 mm long, 0.60 mm wide. Color: Head with dorsal surface

dark brown, nearly black; labrum dark brown; maxillary palpi and antennae testaceous. Pronotum testaceous at anterior

and posterior 0.33, reddish brown in center 0.33; elevated areas between external foveolae somewhat lighter than disc.

Elytra brown. Ventral surface brown except legs, elytral epipleura, and inflexed margin of pronotum, light brown. Head:

Length 0.20 mm. Width 0.36 mm. Frons moderately punctured, interstices equal to or slightly greater than puncture

diameter; surface shining; Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture nearly straight

across middle in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.24/0.12/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface nearly straight in basal 0.33, arcuate in apical 0.66, median surface arcuate;

palpomere 4 widest slightly past midlength. Mentum wider than long, microreticulate. Submentum microreticulate. Genae

shining; lateral area of each gena with well developed foveola; posterior ridge nearly imperceptible. Postgena with

microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly greater than

0.20 interocular distance in width. Thorax: Pronotum length at midline 0.36 mm; maximum width (at approximately

midlength) 0.46 mm; sides margined, denticulate; sides moderately produced at middle, very slightly sinuate and slightly

convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.38 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.40 mm wide, slightly

arcuate to rear. Posterointernal foveolae well developed; punctures in foveola closer together than those on disc.

Posteroexternal well developed. Interfoveolar depression moderately developed. Area between external foveolae

moderately elevated. Anteroexternal foveolae well developed, each foveola some what crescent shaped, extended across

slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area

somewhat closer together than punctures on disc. Disc shining, punctures well impressed, separated by puncture diameter;

many punctures with seta extended above cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate

hind margin. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated from median carina by

thin shelf; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to

posterior; median carina extended to base of intercoxal process; intercoxal process relatively broad, sides tapered, apex

blunt, width at apex nearly 0.66 distance between internal and median carinae. Metasternum with plaques well developed,

somewhat triangular, convergent moderately from posterior to anterior; plaques 0.40 length of metasternum in midline;

greatest width of each plaque slightly less than width of intercoxal process at its apex; plaques separated posteriorly by

approximately twice plaque width; plaques flat in cross section (Fig. 40E). Elytra: Length 0.88 mm. Maximum width (at

midlength) 0.60 mm. Surface shining, disc with well impressed randomly arranged puncture; sutural and second row of

punctures somewhat serial, other punctures randomly arranged; punctures rather well impressed; most punctures with

seta. Explanate margin rather well developed, ended near posterior 0.10, with extremely fine serrations near anterior

angles and apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely

toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin

arcuate. Glabrous segments at apex moderately produced. Segment 7 without emargination at apex. Legs: Protibia very

slightly excavate on inner surface in apical 0.33. Metatibia nearly parallel in apical 0.66. Genitalia: Aedeagus as

illustrated (Figs. 41 A-B) (20 examined).

Variation. - Males from Indiana have the apex of the aedeagus shaped slightly differently

from that of the holotype. I have illustrated an example (Fig. 40B).

Natural History. - The stream at the type-locality is very small, the beetles being taken

from the sand at the margin. Consocies included Limnebius ozapalachicus and Paracymus sp.

H.S. Dybas has collected adults during their dispersal flight, between 4:45 and 5:15 pm,

August 14, 1971.

Western Hemisphere Hydraenidae

137

Figs. 41 A - D, Aedeagi of Hydraena species. (A) H. ozarkensis, holotype. (B) H. ozarkensis, variant from Monroe

County, Indiana. (C) H. maureenae , holotype. (D) H. exilipes , holotype.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Distribution. - (Figs. 42B,167). Ozark Plateau of Missouri, Tennessee, Indiana and

Oklahoma.

Etymology. - Latin, ozarkensis, in reference to the geographical distribution.

43. Hydraena maureenae new species

(Figs. 41C,42B, 167)

Type-locality. - Twelve miles S. Williamsville, Bath County, Virginia.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. I collected these specimens, October 6, 1973. The following seven paratypes (PDP)

were taken at the same locality: 1 female, April 21, 1974; 1 male, June 4, 1974; 1 male, 4

females, April 21, 1975.

Diagnosis. - H. maureenae adults are readily distinguished from all other members of the

lee chi Group which have a scintilla, except H. ozarkensis , by the random, non-serial

arrangement of the punctures on the elytral disc plus its small size, about 1.46 mm long. From

H. ozarkensis adults, those of H. maureenae are distinguished by slightly greater length,

narrower body form, distribution (Fig. 42B), and aedeagus (Figs. 41 A-C).

Description. — Form: Elongate. Size: Holotype 1.46 mm long, 0.58 mm wide. Color: head with dorsal surface and

labrum dark brown; maxillary palpi and antennae testaceous. Pronotum testaceous at anterior and posterior 0.25, reddish

brown in center 0.33; elevated areas between external foveolae somewhat lighter than disc. Elytra testaceous, slightly

darker than testaceous areas of pronotum. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of

pronotum testaceous. Head: Length 0.20 mm. Width 0.38 mm. Frons moderately punctured, interstices equal to or slightly

greater than puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus finely microreticulate.

Labroclypeal suture nearly straight across middle in dorsal aspect. Labrum bilobed, microreticulate, each lobe

symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.28/0.12/0.20; palpomere 2 bent outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight in basal

0.33; arcuate in apical 0.66, median surface similarly shaped; palpomere 4 widest at apical 0.33. Mentum wider than long,

surface moderately shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of each gena with

well developed foveola; posterior ridge nearly imperceptible. Postgena with microreticulation slightly larger than that of

submentum. Last five antennomeres pubescent. Eyes slightly less than 0.17 interocular distance in width. Thorax:

Pronotum length at midline 0.36 mm; maximum width (at approximately midlength) 0.50 mm; sides margined,

denticulate; sides well produced at middle, very weakly sinuate and convergent to anterior angle, sinuate and convergent to

posterior; anterior border 0.40 mm. wide, straight and nearly perpendicular to midline in lateral 0.20, moderately arcuate

to rear in middle 0.60; posterior border 0.40 mm wide, slightly arcuate to rear. Posterointernal foveolae well developed;

punctures in foveola closer together than those on disc. Posteroexternal foveolae well developed. Interfoveolar depression

well developed. Area between external foveolae clearly elevated. Anteroexternal foveolae well developed, each foveola

somewhat crescent shaped, occupying slightly less than 0.33 width of anterior region of pronotum. Transverse foveola

slightly developed, punctures separated by thin walls. Disc shining, punctures well impressed, separated by 0.50 puncture

diameter near anterior and posterior borders, by puncture diameter in middle; some punctures with seta extended above

cuticle in dry specimens. Scintilla distinct, flat, impunctate shelf with arcuate anterior and posterior margins. Prosternum

carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in

lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior median carina

extended to base of intercoxal process; intercoxal process relatively broad, sides nearly parallel, apex blunt, width at apex

nearly 0.66 distance between internal and median carinae. Metasternum with plaques well developed, triangular, medial

margins parallel; plaques 0.40 length of metasternum in midline; greatest width of each plaque 0.66 width of intercoxal

process at its midlength; plaques separated posteriorly by approximately twice plaque width; plaques flat in cross section.

Elytra: Length 0.94 mm. Maximum width (at midlength) 0.58 mm. Surface shining, disc with sutural, second, third and

fourth rows of punctures somewhat serial, other punctures randomly arranged; most punctures with seta. Explanate

margin narrow, ended near posterior 0.10; with extremely fine serrations near anterior angles and apices. Elytral apices, in

dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with

opposite elytron. Abdomen : Intercoxal segment flat, width twice length; anterior angle rounded; posterior margin arcuate.

Glabrous segments at apex moderately produced. Segment 7 without emargination at apex. Legs: Protibia with arcuate

lateral surface, nearly straight medial surface. Metatibia very slightly wider at midlength than at apex. Genitalia:

Aedeagus as illustrated (Fig. 41C)(3 examined).

Western Hemisphere Hydraenidae

139

Figs. 42A - B, Geographical distributions of Hydraena species. (A) H. cuspidicollis • , H. prieto ★ and H. mexicana

A (B) H. ozarkensis • , H. maureenae ★ , H. punctata A and H. youngi ■ .

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Natural History. - The substratum at the margin of the small stream at the type-locality

(Fig. 193B) consisted of small to moderately large, smooth slate fragments. Consocies included

a very large population of Limnebius ozapalachicus plus a few specimens of L. discolor and L.

richmondi.

Distribution. - (Figs. 42B,167). Presently known only from the type-locality in the

Appalachian Mountains of Virginia.

Etymology. - I am very pleased to dedicate this species to my wife Maureen Ellen, who has

assisted me in collecting aquatic Coleoptera throughout North and Central America, and who

has been a constant source of encouragement during the course of this study.

The particeps Subgroup

Members of the particeps Subgroup lack a pronotal scintilla and do not have the

anteromedial region of the metasternum elevated to form a ridge (cf. the argutipes Subgroup).

Adults of most of the nine species presently known for this subgroup are quite small.

Geographically, this group ranges from Brazil northward through Central America and the

Antilles to southern Mexico and the eastern United States as far north as Massachusetts.

44. Hydraena orcula new species

(Figs. 43D,168)

Type-locality. - Ria Chim, Mosquito, Goias, Brazil.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. Harley P. Brown collected these specimens, June 17, 1968.

Diagnosis. - Small size, about 1.16 mm long, and plaque shape serve to distinguish H.

orcula adults from adults of other species of the leechi Group which lack a scintilla and have

well developed posterointernal foveolae. The plaques are narrow, about 0.33 the length of the

metasternum; the distance separating the plaques being four times the width of a plaque, and

equal to the length of a plaque. The aedeagus (Fig. 43D) is unique.

Description. — Form: Ovate. Size: Holotype 1.16 mm long, 0.50 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and posterior

0.25, dark brown in center 0.50; sides slightly lighter than center. Elytra brown, approximately midway in color between

extremes of pronotum. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum

testaceous. Head: Length 0.16 mm. Width 0.32 mm. Frons moderately punctured, interstices equal to or slightly greater

than puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture

arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpi missing from holotype, allotype with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.22/0.08/0.16; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral and median surfaces slightly arcuate; palpomere 4

widest at apical 0.33. Mentum wider than long, surface moderately shining, microreticulate. Submentum microreticulate.

Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with

microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25

interocular distance in width. Thorax: Pronotum length at midline 0.28 mm; maximum width (at approximately

midlength) 0.40 mm; sides margined, denticulate; sides relatively slightly produced at middle, slightly arcuate and slightly

convergent to anterior angle, slightly sinuate and slightly convergent to posterior; anterior border 0.34 mm wide, straight

and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.36 mm

wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola closer together than

those on disc, some confluent. Posteroexternal foveola delimited by very shallow depression with punctation somewhat

closer than that of disc. Interfoveolar depression slightly developed. Area between external foveolae weakly elevated.

Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33

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141

width of anterior region of pronotum. Transverse foveola slightly developed, with punctures closer together than

punctures on disc. Disc shining, punctures moderately fine, separated by 0.25 puncture diameter near anterior and

posterior borders, by puncture diameter in middle; punctures each with distinctive seta extended above cuticle in dry

specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by

thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent

from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow,

sides parallel, apex rounded, width 0.66 distance between internal and median carinae. Metasternum with plaques well

developed, somewhat triangular, median margins nearly parallel; plaques 0.33 length of metasternum in midline;

plaques separated posteriorly by approximately plaque length, which is equal to four times plaque width; plaques flat in

cross section. Elytra: Length 1.16 mm. Maximum width (at midlength) 0.50 mm. Surface shining, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width

approximately equal to puncture diameter, as are interstices between adjacent punctures of a row; punctures each with

seta. Explanate margin quite narrow, ending near posterior 0.20, with extremely fine serrations at anterior angles.

Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated very slightly, obliquely

toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle,

posterior margin weakly arcuate. Glabrous segments at apex weakly produced. Apical segment without emargination at

apex. Legs: Without apparent modification. Genitalia: Aedeagus as illustrated (Fig. 43D)(1 examined).

Distribution. - (Fig. 168). Known only from the type-locality in the state of Goias, Brazil.

Etymology. - Latin, orca (whale) plus ula (diminutive). Named in reference to the shape of

the aedeagus.

45. Hydraena sahlbergi d’Orchymont

(Fig 168)

Hydraena sahlbergi d’Orchymont, 1923:40 (holotype female in HM; type-locality: Santa Rita, Minas Gerais, Brazil).

Diagnosis. - Readily distinguished from other members of the leechi Group found in the

same geographical area, (mountains of southeastern Brazil), by absence of a pronotal scintilla.

Refer to the diagnosis of H. spangleri for additional comments.

Description. — Form: Elongate. Size: Holotype 1 .57 mm long, 0.68 mm wide. Color: Head with dorsal surface dark

brown; labrum brown; maxillary palpi and antennae testaceous. Pronotum dark brown except testaceous band at anterior

and posterior borders; width of band about 0.17 length of pronotum. Elytra brown. Ventral surface brown except legs,

elytral epipleura and indexed margin of pronotum testaceous. Head: Length 0.27 mm. Width 0.39 mm. Frons shiny,

moderately punctate, interstices one-two times puncture diameter. Frontoclypeal suture straight. Clypeus microreticulate.

Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median

emargination ended at about midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4

respectively: 0.26/0.09/0.19; palpomere 2 bent outward at about midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface nearly straight, medial surface arcuate, widest near midlength. Mentum wider

than long, surface moderately shining, microreticulate. Submentum microreticulation similar to mentum. Genae shining,

finely punctulate; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with

microreticulation similar to that of submentum. Last five antennomeres pubescent. Eyes 0.17 interocular distance in

width. Thorax: Pronotum length at midline 0.41 mm; maximum width (at approximately midlength) 0.51 mm; sides

margined, denticulate; sides relatively slightly produced at middle, nearly straight and convergent to anterior angle, very

slightly sinuate and convergent to posterior; anterior border 0.44 mm wide, straight and nearly perpendicular to midline in

lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.48 mm wide, slightly arcuate to rear.

Posterointernal foveolae weakly developed; punctures in foveola closer together than those on disc. Posteroexternal foveola

delimited by very shallow depression with punctation somewhat closer than that of disc. Interfoveolar depression absent.

Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extneded across slightly less than 0.33

width of anterior region of pronotum. Transverse foveola not developed, punctures in this area somewhat closer together

than punctures on disc. Disc dull, punctures moderately sized, very deeply impressed, separated by narrow walls near

anterior and posterior borders, and by 0.50 puncture diameter in middle; most punctures without distinctive seta extended

above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine; coxae

separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively

narrow, sides nearly parallel, apex blunt, width at apex 0.66 distance between internal and median carinae. Metasternum

with plaques well developed, slightly arcuate, convergent moderately from posterior to anterior; each plaque tapered from

posterior to anterior; plaques 0.50 length of metasternum in midline; greatest width of each plaque 0.66 width of intercoxal

process at its midlength; plaques separated posteriorly by approximately three times plaque width; plaques flat in cross

section. Elytra: Length 1.02 mm. Maximum width (at midlength) 0.68 mm. Surface shining, disc with 10 rows of

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markedly impressed punctures between suture and humeral callus; puncture shape irregular; intervals not elevated,

width approximately equal to 0.25 puncture diameter, somewhat irregular due to displacement by punctures; interstices

between adjacent punctures of row approximately 0.25 puncture diameter; each puncture with seta. Explanate margin

quite narrow, ended near posterior 0.20 with extremely fine, well separated serrations along entire margin. Elytral

apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form

of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Legs:

Without apparent modification. Genitalia: Males unknown.

Distribution. - (Fig. 168). Known only from the type-locality, Santa Rita, Minas Gerais,

Brazil.

Remarks. - Other than the holotype I have seen only a single female from the type-locality

(BMNH).

46. Hydraena particeps new species

(Figs. 43A-B,59,168)

Type-locality. - Calabozo, 32 km. SW, Guarico, Venezuela.

Type-specimens. - The holotype male, which was collected by Paul J. Spangler, February

11, 1969, is deposited in USNM. The allotype, from Albrook Forest Site, Canal Zone, Panama,

is also deposited in USNM. Paratypes (22) are listed in the appendix.

Diagnosis. - The plaques are moderately long and narrow, separated by about four times

the width of a plaque. Additionally, the pronotum lacks a scintilla and has well developed

posterointernal foveolae, and the metasternum does not have the anteromedial region elevated.

These features, plus the distinctive aedeagus (Figs. 43A-B), serve as the diagnostic

characteristices for H. particeps.

Description. — Form: Elongate. Size: Holotype 1.40 mm long, 0.48 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and posterior

0.25, dark brown in center 0.50; sides slightly lighter than center. Elytra brown, approximately midway in color between

extremes of pronotum. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of pronotum brown.

Head: Length 0.20 mm. Width 0.38 mm. Frons moderately punctured, interstices equal to or slightly less than puncture

diameter; surface moderately shining; posterior margin very slightly emarginate in midline. Frontoclypeal suture straight.

Clypeus microreticulate. Labroclypeal suture nearly straight across middle in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.26/0.10/0.18; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral and median

surfaces slightly arcuate, widest near midlength. Mentum wider than long, surface moderately shining, microreticulate.

Submentum microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent.

Postgena with microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes 0.25

interocular distance in width. Thorax: Pronotum length at midline 0.38 mm; maximum width (at approximately

midlength) 0.50 mm; sides margined, denticulate; sides moderately produced at middle, slightly sinuate and convergent to

anterior angle, slightly sinuate and convergent to posterior; anterior border 0.42 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.46 mm wide, slightly

arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola similar to those on disc.

Posteroexternal foveola delimited by very shallow depression with punctation somewhat closer than that of disc.

Interfoveolar depression weakly developed. Area between external foveolae nearly flat. Anteroexternal foveolae well

developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of

pronotum. Transverse foveola weakly developed, with punctures somewhat closer together than punctures on disc. Disc

shining, punctures fine, separated by 0.50 puncture diameter near anterior and posterior borders, by puncture diameter in

middle; punctures each with distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum

carinate, carina produced anteriorly into very short spine; coxae separated by a thin, median carina; carina sinuate line in

lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior ; median carina

extended to base of intercoxal process; intercoxal process relatively narrow, sides nearly parallel, apex blunt, width at apex

0.50 distance between internal and median carinae. Metasternum with plaques well developed, straight, convergent

moderately from posterior to anterior; plaques 0.36 length of metasternum in midline: width of each plaque 0.66 width of

intercoxal process; plaques separated posteriorly by approximately four times plaque width; plaques flat in cross section.

Elytra: Length 1.00 mm. Maximum width (at midlength) 0.48 mm. Surface shining, disc with 10 rows of punctures

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143

Figs. 43 A - D, Aedeagi of Hydraena species. (A) H. particeps , holotype. (B) H. particeps variant from Honduras. (C) H.

decui , holotype. (D) H. orcula, holotype.

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Perkins

between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width

approximately equal to puncture diameter, interstices between adjacent punctures of a row slightly smaller; punctures

each with seta. Explanate margin quite narrow, ended near posterior 0.20, with extremely fine serrations near apices.

Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture,

in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin arcuate.

Glabrous segments at apex moderately produced. Apical segment without emargination at apex. Legs: Protibia with

slight emargination on inner surface near midlength. Other legs without apparent modification. Genitalia: Aedeagus as

illustrated (Figs. 43A-B) (13 examined).

Natural History . - The notation, “pocket of damp leaves in dry streambed”, is the only

microhabitat information presently available.

Distribution. - (Figs. 59,168). From Honduras south to Panama and east through

Venezuela to Trinidad and Grenada.

Variation. - The single male I have seen from Honduras, the northernmost locality known to

date, has an aedeagus (Fig. 43B) of slightly different form than the other males studied

(Fig. 43 A). Externally this specimen is noticably more densely punctate on the pronotum, but

agrees quite well in other respects. This specimen might represent another species, but I prefer

to treat it as an aedeagal morph until more material from Central America becomes available

for study.

Etymology. - Latin, particeps (comrade, partner, sharing). Named in reference to the

phylogenetic relationship of this species to H. decui, as indicated by the aedeagus.

47. Hydraena decui Spangler

(Figs. 43C,168)

Hydraena decui Spangler, 1980:329 (holotype male in USNM; type-locality: Arroyo de la Poa, Sabanilla, Cuba).

Diagnosis. - Transverse pronotum, widely separated plaques and aedeagal form serve as

diagnostic characteristics for adults of this small, rather broad Cuban species.

Description. — Form: Ovate, moderately broad. Size: Holotype 1.18 mm long, 0.52 mm wide. Color: Entirely

testaceous except for dark brown frons and light brown, indistinct pronotal macula. Head: Length 0.18 mm, width

0.30 mm. Frons finely, moderately densely punctate, interstices shiny. Frontoclypeal suture slightly arcuate. Clypeus

finely punctulate, faintly microreticulate laterally. Labroclypeal suture straight. Labrum microreticulate, bilobed, median

emargination ending near midlength. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4 respectively:

0.20/0.08/0. 1 5; palpomere 4 unusually slender, widest near midlength, outer edge straight. Mentum wider than long, dull,

microreticulate. Submentum microreticulate. Genae shiny, foveolate laterally. Postgena microreticulate. Thorax:

Pronotum length at midline 0.29 mm; maximum width (at midlength) 0.43 mm; sides margined, very finely denticulate,

distinctly produced at middle, slightly arcuate and convergent to anterior angles, sinuate and convergent to posterior

angles; anterior border 0.34 mm wide, straight and perpendicular to midline in lateral 0.25, slightly arcuate to rear in

posterior 0.50; posterior border 0.35 mm wide, very slightly arcuate to rear. Posterointernal and posteroexternal foveolae

absent. Anteroexternal foveolae well developed, each somewhat crescent shaped, extended across slightly less than 0.33

width of anterior region of pronotum. Transverse foveola absent. Disc shiny, finely moderately densely punctate, punctures

separated by one-two times puncture diameter; punctures without apparent setae. Scintilla absent. Prosternum carinate;

carina between coxae, sinuate in lateral view. Mesosternum with internal and external carinae divergent from anterior to

posterior; median carina extended to base of intercoxal process; intercoxal process of moderate width, apex blunt, width at

apex 0.50 distance between internal and median carinae. Metasternum with plaques small, narrow, length about equal to

width of intercoxal process, width 0.50 length; plaques separated by about five times plaque width. Elytra: Length

0.73 mm. Maximum width (at midlength) 0.52 mm. Disc shiny, with 10 rows of small, close-set punctures between suture

and humeral callus; intervals not elevated, width less than puncture diameter, as are interstices between punctures of a

row; most punctures with very fine seta. Explanate margin well developed, ending near posterior 0.20, finely serrate.

Elytral apices very slightly dehiscent, in posterior aspect elytral margin elevated obliquely toward suture, in form of angle

with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Legs: Profemur with

low carina on inner surface near base. Protibia slightly arcuate. Other legs moderately slender, unmodified. Genitalia:

Aedeagus as illustrated (Fig. 43C)(1 examined).

Distribution. - (Fig. 168). Cuba.

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145

48. Hydraena guadelupensis d’Orchymont

(Figs. 44D,59,168)

Hydraena guadelupensis d’Orchymont, 1923:37 (holotype male in 1SNB; type-locality: Guadeloupe). - d’Orchymont,

1945a: 1-4.

Diagnosis. - Small size, about 1.30 mm long, and the elytral apices which, when viewed

posteriorly, do not turn upwards toward the suture serve to distintuish H. guadelupensis adults

from other members of the leechi Group occupying the same geographical area (Fig. 59). Refer

to the diagnosis of H. spangleri for further comments.

Description. — Form: Elongate-oval. Size: Holotype 1.30 mm long, 0.55 mm wide. Color: Head with dorsal surface

dark brown; labrum brown; maxillary palpi and antennae testaceous. Pronotum testaceous except for transverse,

rectangular brown (lighter than head) macula on disc approximately 0.18 mm long, 0.30 mm wide; macula at borders

blended into surrounding testaceous areas. Elytra same color as pronotal macula. Ventral surface dark brown except legs,

plaques, elytral epipleurae and inflexed margin of pronotum brown. Head: Length 0.19 mm. Width 0.32 mm. Frons finely

and sparsely punctate, interstices one to three times puncture diameter; surface shining. Frontoclypeal suture arcuate to

rear. Clypeus microreticulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe

symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.23/0.10/0.16; palpomere 2 bent outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight in basal

0.33, arcuate in apical 0.66, median surface arcuate; apical segment widest near distal 0.33. Mentum wider than long,

surface moderately shining, microreticulate. Submentum microreticulation similar to mentum. Genae shining; lateral area

of each gena with a well developed foveola; posterior ridge absent. Postgena with microreticulation similar to that of

submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax:

Pronotum length at midline 0.32 mm; maximum width (at approximately midlength) 0.55 mm; sides margined,

denticulate; sides moderately produced at middle, arcuate and convergent to anterior angle, sinuate and convergent to

posterior; anterior border 0.37 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate

to rear in middle 0.50; posterior border 0.40 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately

devloped; punctures in foveola similar to those on disc. Posteroexternal foveola delimited by very shallow depression with

punctation somewhat closer than that of disc. Interfoveolar depression weakly developed. Area between external foveolae

not elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across less than

0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area somewhat closer

together than punctures on disc. Disc shining, punctures fine, separated by twice puncture diameter; most punctures with

seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very

short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and

external carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal

process relatively narrow, sides nearly parallel; apex blunt, width at apex 0.50 distance between internal and median

carinae. Metasternum with plaques well developed, straight, convergent moderately from posterior to anterior; plaques

0.43 length of metasternum in midline; width of each plaque subequal to width of intercoxal process at its midlength;

plaques separated posteriorly by approximately twice plaque width; plaques separated anteriorly by 1.50 plaque width;

plaques flat in cross section. Elytra: Length 0.83 mm. Maximum width (at midlength) 0.55 mm. Surface shining, disc with

10 rows of punctures between suture and humeral callus, rows quite Regular; most punctures round; intervals not elevated,

width approximately equal to puncture diameter, as are interstices between adjacent punctures of a row; most punctures

without perceptible seta. Explanate margin quite narrow, ended near posterior 0.20, with extremely fine, well separated

serrations along entire margin; serrations slightly closer near apices. Elytral apices, in dorsal aspect, gradually rounded; in

posterior aspect, elytral margin not elevated obliquely toward suture, not in form of angle with opposite elytron. Abdomen:

Intercoxal segment flat, wider than long, posterior margin straight. Glabrous segments at apex only moderately produced.

Segment 7 without emargination at apex. Legs: Protibia slightly arcuate; other legs without apparent modification.

Genitalia: Aedeagus as illustrated (Fig. 44D)(21 examined).

Variation. - The aedeagus of the single male I have seen from Costa Rica has the apex

slightly different from that of other specimens (Fig. 44D). Length and general proportions of

this aedeagus are virtually identical to aedeagi of specimens from Guadeloupe and Jamaica.

Externally, this beetle is very slightly smoother than those from the remainder of the

distribution. I have examined 59 specimens (see appendix).

Natural History. - The only microhabitat notations present in the locality data are “sifted

from swamp litter” and “ex small pool in narrow gully”.

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Perkins

Distribution. - (Figs. 59,168). Guadeloupe, Jamaica and Costa Rica.

49. Hydraena spangleri new species

(Figs. 44C,56B,168)

Type-locality. - Plummer’s Island, Montgomery County, Maryland.

Type-specimens. - The holotype male and allotype with identical data are deposited in

USNM. Paul J. Spangler collected these specimens, November 1, 1960. Paratypes (150) are

listed in the appendix.

Diagnosis. - Small size, about 1.30 mm long, and lack of a distinct pronotal scintilla readily

distinguish adults of H. spangleri from those of all other species of the leechi Group which

occupy the same geographical area (Fig. 56B). H. spangleri adults are externally very similar

to those of the putative sister-species, H. guadelupensis from the Antilles and Costa Rica. H.

guadelupensis adults are slightly narrower, generally less densely punctate and do not have the

elytral margins turned upwards toward the suture, in posterior aspect. Aedeagi of males of the

two species (Figs. 44C-D) are distinct, but obviously markedly similar. Adults of these two

species are similar to those of H. sahlbergi in that all three species have (1) serial elytral

punctures, (2) lack a median metasternal ridge posterior to the mesosternal process, and (3)

have the metasternal plaques convergent anteriorly. H. sahlbergi adults however, are larger

(about 1.57 mm long), with narrower elytral intervals and are known only from southeastern

Brazil.

Description. — Form: Elongate-oval. Size: Holotype 1.30 mm long, 0.55 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and

posterior 0.25, brown in middle 0.50, sides slightly lighter than center. Elytra brown. Ventral surface dark brown except

legs, elytral epipleura, apex of abdomen and inflexed margin of pronotum, testaceous. Head: Length 0.16 mm. Width

0.32 mm. Frons moderately punctate, interstices equal to or slightly greater than puncture diameter; surface shining.

Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3, and 4, respectively: 0.20/0.08/0.16; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral and medial

surfaces slightly arcuate. Mentum longer than wide, surface moderately shining, finely punctulate. Submentum

microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with

microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly greater than

0.25 interocular distance in width. Thorax: Pronotum length at midline 0.32 mm; maximum width (at approximately

midlength) 0.46 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate and slightly

convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.36 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.40 mm wide, slightly

arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola closer together than those on disc.

Posteroexternal foveola delimited by very shallow depression with punctation somewhat closer than that of disc.

Interfoveolar depression slightly developed. Area between external foveolae nearly flat. Anteroexternal foveolae well

developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of

pronotum. Transverse foveola slightly developed, with punctures separated by thin walls. Disc shining, punctures fine and

close, separated by less than puncture diameter; most punctures with seta extended above cuticle in dry specimens.

Scintilla absent, represented by narrow, reflective, impunctate area. Prosternum carinate, carina produced anteriorly as

very short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal

and external carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal

process relatively narrow, sides parallel, apex somewhat rounded, width near apex 0.50 distance between internal and

median carinae. Metasternum with plaques well developed, straight, convergent from posterior to anterior; plaques 0.50

length of metasternum in midline; plaques separated posteriorly by approximately twice plaque width; plaques separated

anteriorly by approximately plaque width; plaques flat in cross section. Elytra: Length 0.86 mm. Maximum width (at

midlength) 0.58 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width approximately equal to puncture diameter; interstices between

adjacent punctures of row 0.50 puncture diameter; punctures each with seta. Explanate margin quite narrow, ended near

posterior 0.20, with extremely fine serrations near anterior angles and apices. Elytral apices, in dorsal aspect, gradually

Western Hemisphere Hydraenidae

147

Figs. 44A - D, Aedeagi of Hydraena holotypes. (A) H. oblio. (B) H. punctata. (C) H. spangleri. (D) H. guadelupensis

(inset: specimen from Costa Rica).

rounded; in posterior aspect, elytral margin not elevated obliquely toward suture, not in form of angle with opposite

elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle, posterior margin very weakly arcuate.

Glabrous segments at apex moderately produced. Segment 7 without emargination at apex. Legs: Protibia arcuate,

enlarged gradually from base to apex. Metatibia straight, gradually enlarged from base to apex. Genitalia: Aedeagus as

illustrated (Fig. 44C)(72 examined).

Natural History. - H. spangleri appears to be primarily a pond species. Habitat notations in

the locality data include “pothole”, “pond”, “debris at swamp edge”, “hardwood hammock”,

“Palmetto-Mahogany swamp”, “under water hyacinth”, “grassy compost mixed with Cypress

Quaest. Ent., 1980, 16 (1,2)

148

Perkins

needles”, “litter in sinkhole”, and “sphagnum”. Adults of H. spangleri are frequently collected

in association with H. atlantica adults in Maryland and with those of H. marginicollis in

Florida. In one locality record provided by W. Suter, adults were found living in sphagnum with

H. ancylis adults in Hardin County, Texas.

Distribution. - (Figs. 56B,168). Generally found in, but not restricted to, coastal areas;

eastern United States, Maryland to Texas.

Etymology. - It is with pleasure that I dedicate this species to Paul J. Spangler in

recognition of his significant contributions to the knowledge of aquatic Coleoptera.

50. Hydraena punctata LeConte

(Figs. 42B,44B,168)

Hydraena punctata LeConte, 1855:362 (holotype male in MCZ; type-locality: Pennsylvania).

Hydraena needhami d’Orchymont, 1929:79 (holotype female in ISNB; type-locality: Ithaca, New York; new synonomy).

D’Orchymont’s type-specimen does not differ significantly from LeConte’s type-specimen.

Refer to the remarks section for additional comments.

Diagnosis. - Among those species of the leechi Group whose adults lack a scintilla, lack a

median, anterior ridge on the metasternum, and have the elytral punctures in series, H.

punctata adults are distinguished by moderately elongate, widely separated plaques. The

plaques converge slightly with one another anteriorly, being separated anteriorly by about four

times the width of a plaque. H. punctata is distinct also in its distribution, being the only

member of the leechi Group living in northeastern United States (Fig. 42B).

Description. — Form: Elongate. Size: Holotype 1.48 mm long, 0.70 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous except apices brown; antennae testaceous. Pronotum testaceous

except for transverse, rectangular, brown (lighter than head) macula on disc which occupies approximately middle 0.56 of

pronotum; macula lighter near sides of pronotum and blended into anterior and posterior testaceous areas. Elytra same

color as testaceous areas of pronotum. Ventral surface dark brown except legs, elytral epipleura and indexed margin of

pronotum brown. Head: Length 0.20 mm. Width 0.40 mm. Frons punctation coarse, deeply impressed, interstices equal to

puncture diameter or less; surface moderately shining. Frontoclypeal suture straight. Clypeus microreticulate.

Labroclypeal suture arcuate when viewed from above. Labrum bilobed, microreticulate, each lobe symmetrical arc;

median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.28/0.10/0.20; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight in basal 0.33, arcuate in

apical 0.66, median surface arcuate; apical segment widest near distal 0.33. Mentum wider than long, surface moderately

shining, microreticulate laterally. Submentum microreticulate. Genae shining, finely microreticulate, lateral area of each

gena with well geveloped foveola; posterior ridge absent. Postgena with microreticulation similar to that of submentum.

Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at

midline 0.40 mm; maximum width (at approximately midlength) 0.52 mm; sides margined, denticulate; sides moderately

produced at middle, sinuate and convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.44 mm

wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior

border 0.46 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola similar

to those on disc. Posteroexternal foveola moderately developed. Interfoveolar depression moderately developed. Area

between external foveolae moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent

shaped, extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola slightly developed,

punctures closer together than punctures on disc. Disc moderately shining, punctures fine and close together, separated by

thin walls near anterior and posterior borders, and by puncture diameter in middle; most punctures with seta extended

above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine; coxae

separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively

narrow, sides nearly parallel, apex blunt, width at apex 0.50 distance between internal and median carinae. Metasternum

with plaques moderately developed, straight, convergent from posterior to anterior; plaques slightly less than 0.50 length of

metasternum in midline; width of each plaque subequal to width of intercoxal process at its midlength; plaques separated

anteriorly by approximately four times plaque width; plaques flat in cross section. Elytra: Length 1.10 mm. Maximum

width (at midlength) 0.55 mm. Surface moderately shining, disc with 10 rows of punctures between suture and humeral

callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal to 0.50 puncture

Western Hemisphere Hydraenidae

149

diameter, as are interstices between adjacent punctures of a row; each puncture with seta. Explanate margin quite

narrow, ended near posterior 0.17, with extremely fine, well separated serrations along entire margin; serrations

somewhat closer near apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin

elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen : Intercoxal segment flat, wider than

long, posterior margin straight. Glabrous segments at apex moderately produced. Segment 7 without emargination at

apex. Legs: Metatibia gradually enlarged from base to apex. Genitalia: Aedeagus as illustrated (Fig. 44B)( 1 3

examined).

Distribution. - (Figs. 42B,168). Northeastern United States: Massachusetts, Connecticut,

New York, New Jersey and Pennsylvania.

Remarks. - In the original description of H. punctata , LeConte (1855) gives the length of

his specimen as “Long. .95”, which is equivalent to about 2.40 mm. This is apparently a

typographical error, as the specimen is actually only 1.48 mm long. D’Orchymont (1923) in his

early paper on American Hydraena comments that he had not seen the type-specimen of H.

punctata , and states further, “Je n’ai vu aucune Hydraena americaine de taille ausse grande.”

This probably explains why d’Orchymont later (1929) mistakenly described a specimen of H.

punctata as H. needhami. Including the two types, a total of 26 specimens were examined (see

appendix).

5 1 . Hydraena oblio new species

(Figs. 44A,59,168)

Type-locality. - Four miles S. Rabinal, Baja Verapaz, Guatemala.

Type-specimens. - The holotype male and allotype with same data are deposited in USNM.

My wife Maureen and I collected these specimens, June 10, 1974. Paratypes (13) are listed in

the appendix.

Diagnosis. - Small size and ovate body form (about 1.24 x 0.56 mm), plus pronotal

sculpture, which lacks a scintilla and has the interstices microreticulate, serve as diagnostic

characteristics for this distinctive species. The pronotum is very dull due to the

microreticulation.

Description. — Form: Ovate. Size: Holotype 1.24 mm long, 0.56 mm wide. Color: Dorsal surface dark brown

except head and disc of pronotum nearly black; maxillary palpi and antennae brown. Ventral surface dark brown except

legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width 0.34 mm. Frons

microreticulate, punctures separated by less than their own diameters, microreticulation more evident in punctures than on

interstices; surface dull. Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture nearly straight when

viewed from above. Labrum bilobed, microreticulate, each lobe slightly asymmetrical; median emargination ending at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.20/0.08/0.14; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface very slightly arcuate, median surface moderately arcuate; palpomere 4 widest

slightly past midlength. Mentum wider than long, surface moderately shining, microreticulate. Submentum

microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge very slightly

developed. Postgena with punctation slightly smaller than that of submentum. Last five antennomeres pubescent. Eyes

0.17 interocular distance in width. Thorax: Pronotum length at midline 0.32 mm; maximum width (at approximately

midlength) 0.46 mm; sides margined, denticulate; sides moderately produced at middle, very slightly sinuate and slightly

convergent to anterior angle, markedly sinuate, and convergent to posterior; anterior border 0.36 mm wide, straight and

nearly perpendicular to midline in lateral 0.17, moderately arcuate to rear in middle 0.50; posterior border 0.40 mm wide,

slightly arcuate to rear. Posterointernal foveolae well developed; punctures in foveola less distinct than those on disc.

Posteroexternal foveola well developed. Interfoveolar depression moderately developed. Area between external foveolae

moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across

slightly less than 0.33 width of anterior region of pronotum. Transverse foveola moderately developed, punctures similar to

those on disc. Disc dull, microreticulate, punctures separated by 0.50 puncture diameter or less, some punctures with seta

extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short

spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and

external carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal

process relatively narrow, sides nearly parallel; apex round, width 0.50 distance between internal and median carinae.

Quaest. Ent., 1980, 16 (1,2)

150

Perkins

Metasternum with plaques weakly developed, consisting of small ovals at posterior 0.20. Elytra: Length 0.82 mm.

Maximum width (at midlength) 0.56 mm. Surface dull, disc with 10 rows of punctures between suture and humeral

callus, rows quite regular; most punctures round but limits difficult to discern, surface uneven; intervals not elevated,

width approximately equal to 0.50 puncture diameter, as are interstices between adjacent punctures of row; each

puncture with seta. Explanate margin quite narrow, ended near posterior 0.12, with fine serrations near anterior angles.

Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture,

in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle, posterior

margin straight. Glabrous segments at apex moderately produced. Segment 7 without emargination at apex. Legs:

Protibia arcuate, very slightly expanded in apical 0.33. Metatibia with straight inner surface, outer surface very slightly

arcuate. Genitalia: Aedeagus as illustrated (Fig. 44A)(6 examined).

Natural History. - The stream at the type-locality is in a transition xeric-tropical zone, the

beetles being collected at the sand-gravel margins (Figs. 191 B-C).

Distribution. - (Figs. 59,168). Inhabits the mountains of Guatemala and Chiapas, Mexico.

Etymology. - oblio , a miscellaneous assemblage of letters.

52. Hydraena youngi new species

(Figs. 42B,45B,168)

Type-locality. - San Felasco Hammock, Alachua County, Florida.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CFMNH. Paratypes with same data (12) are deposited in FNY, USNM, and PDP. Frank

N. Young collected these specimens, October 28, 1947. One additional male paratype (PDP)

has the following data: Maryland, Worcester County, Pokomoke City, October 16, 1977, H. E.

Sprance. One additional female paratype (PDP), collected by Hubbard and Schwarz, is from

Ft. Monroe, Virginia.

Diagnosis. - Immediately distinguished from other Western Hemisphere Hydraena adults

by narrow body form (1.96 x 0.56 mm) and rugulose, dull pronotum. The aedeagus (Fig. 45b)

is extremely unusual.

Description. — Form: Narrow, elongate. Size: Holotype 1.96 mm long, 0.56 mm wide. Color: Head with dorsal

surface dark brown; labrum brown; maxillary palpi and antennae testaceous. Pronotum with an indistinctly defined, brown

macula on disc, remainder testaceous. Elytra brown. Ventral surface brown except legs, elytral epipleurae and inflexed

margins of pronotum ochraceous. Head: Length 0.20 mm. Width 0.34 mm. Frons moderately finely and closely punctured;

interstices equal to or slightly less than puncture diameter, surface dull, extremely uneven, limits of punctures difficult to

see with light reflected from surface. Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture arcuate

in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc, median emargination ended at

approximately midlength of labrum. Maxillary palpus with follqwing lengths (mm) of palpomeres 2, 3 and 4, respectively:

O. 26/0.12/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface nearly straight in basal 0.33, arcuate in apical 0.66, median surface arcuate;

palpomere 4 widest past midlength. Mentum wider than long, surface dull, microreticulate. Submentum microreticulate.

Genae dull, lateral area of each gena with well developed foveola; posterior ridge nearly imperceptible. Postgena with

microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.20

interocular distance in width. Thorax: Pronotum length at midline 0.38 mm; maximum width (at approximately

midlength) 0.48 mm; sides margined, denticulate; sides relatively weakly produced at middle, very slightly arcuate and

slightly convergent to anterior angle, markedly sinuate and slightly convergent to posterior; anterior border 0.40 mm wide,

straight and nearly perpendicular to midline in lateral 0.14, markedly arcuate to rear in middle 0.71; posterior border

0.44 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in foveola similar to

those on disc. Posteroexternal foveola delimited by very shallow depression with punctation somewhat closer than that of

disc. Interfoveolar depression very slightly developed. Area between external foveolae not elevated. Anteroexternal

foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior

region of pronotum. Transverse foveola not developed, punctures in this area somewhat closer together than punctures on

disc. Disc dull, punctures fine, separated by 0.50 puncture diameter near anterior and posterior borders, by puncture

diameter in middle; interstices extremely uneven, limits of punctures difficult to see with light reflected from surface;

punctures with distinctive setae extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina

produced anteriorly as very short spine; coxae separated by thin, median carina; carina arcuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to base of

Western Hemisphere Hydraenidae

151

B

Figs. 45 A - B, Aedeagi of fiydraena holotypes. (A) H. cuspidicollis. (B) H. youngi (inset: specimen from Worcester

County, Maryland).

intercoxal process; intercoxal process relatively narrow, tapered from base to apex, apex blunt, width at apex slightly

less than 0.50 distance between internal and median carinae. Metasternum with plaques well developed, triangular,

median margins parallel; plaques nearly 0.50 length of metasternum in midline; plaques flat in cross section. Elytra:

Length 1.04 mm. Maximum width (at midlength) 0.56 mm. Surface dull, disc with 10 rows of punctures between

suture and humeral callus, rows 2-5 (from suture) somewhat irregular; most punctures round; intervals not elevated,

width approximately equal to puncture diameter, as are interstices between adjacent punctures of a row; surface of

interstices somewhat uneven; punctures each with seta. Explanate margin quite narrow, ended near posterior 0.20, with

fine serrations near anterior angles. Elytral apices, in dorsal aspect, somewhat produced; in posterior aspect, elytral

margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat,

nearly an equilateral triangle, posterior margin arcuate. Glabrous segments at apex well produced, somewhat flat on

ventral surface. Apical segment without emargination at apex. Legs: Profemur with a small tubercle on inner surface at

midlength. Protibia very slightly arcuate. Genitalia: Aedeagus as illustrated (Fig. 45B)(7 examined).

Variation. - The aedeagus of the single male known from Maryland (Fig. 45B, inset) differs

slightly from that of specimens from Florida. Externally, this specimen agrees well with the

Floridian individuals.

Distribution. - (Figs. 42B,168). Known only from the type-locality in Florida and one

locality in Maryland.

Etymology. - I am pleased to dedicate this species to Frank N. Young, in recognition of his

many contributions to the knowledge of way of life and systematics of aquatic Coleoptera.

The argutipes Subgroup

Adults of this subgroup are characterized by absence of a pronotal scintilla, absence of a

brush of hairs on the metatibiae of males, and the presence of an elevated ridge, more or less

Quaest. Ent., 1980, 16 (1,2)

152

Perkins

developed, on the anteromedial region of the metasternum (e.g .H. cuspidicollis ), (Fig. 48D).

Adults of several of the eight included species have the pronotum distinctively incised on the

sides in the posterior 0.50. Two of the species, H. bractea and H. bractoides , have the male

metatibiae arcuate and expanded.

As is currently known, the subgroup is restricted to montane areas of Mexico from Oaxaca

to Durango.

53. Hydraena oaxaca new species

(Figs. 46D,169)

Type-locality. - One mile N. Ixtlan de Juarez, Oaxaca, Mexico.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. Paratypes consist of two specimens, one of each sex, from the same locality (PDP).

These specimens were collected by my wife Maureen and I, July 5, 1974.

Diagnosis. - The metasternal plaques are well developed, subtriangular, separated by

slightly more than the greatest width of a plaque. This characteristic plus the well developed

median ridge on the anterior portion of the metasternum and the moderately large size, about

1.70 mm long, serve to distinguish H. oaxaca adults from the other members of the leechi

Group which have serial punctures on the elytra and lack a pronotal scintilla.

Description. — Form: Elongate. Size: Holotype 1.70 mm long, 0.72 mm wide. Color: Dorsal surface dark brown

except border of pronotum, slightly lighter. Maxillary palpi testaceous; antennae testaceous. Ventral surface dark brown

except legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.22 mm. Width 0.40 mm. Frons

moderately punctured, interstices equal to or slightly less than puncture diameter; surface shining. Frontoclypeal suture

straight. Clypeus microreticulate, Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, each lobe symmetrical

arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.28/ 0.10/0.22; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface straight, median surface arcuate; apical

segment widest near midlength. Mentum wider than long, surface moderately shining, microreticulate. Submentum

microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with

microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25

interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately

midlength) 0.56 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate and slightly

convergent to anterior angle, slightly sinuate and convergent to posterior; anterior border 0.44 mm wide, straight and

nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.48 mm wide,

slightly arcuate to rear. Posterointernal foveolae weakly developed; punctures in foveola similar to those on disc.

Posteroexternal foveola delimited by very shallow depression with punctation somewhat closer than that of disc.

Interfoveolar depression moderately developed. Area between external foveolae moderately elevated. Anteroexternal

foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior

region of pronotum. Transverse foveola slightly developed, with punctures somewhat closer together than punctures on

disc. Disc shining, punctures moderately large and deeply impressed, separated by thin walls near anterior and posterior

borders, by puncture diameter or slightly less in middle; each puncture with distinctive seta extended above cuticle in dry

specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin,

median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from

anterior to posterior; median median carina extended to base of intercoxal process; interocoxal process relatively broad,

sides parallel, apex blunt, width at apex subequal to distance between internal and median carinae. Metasternum with

ridge posterior to intercoxal process; plaques well developed, somewhat triangular, parallel; plaques 0.50 length of

metasternum in midline, greatest width of each plaque subequal to width of intercoxal process; plaques separated

posteriorly by approximately 1.50 times plaque width; plaques flat in cross setion. Elytra: Length 1.08 mm. Maximum

width (at midlength) 0.72 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows

quite regular; most punctures round; intervals not elevated, width approximately equal to puncture diameter, interstices

between adjacent punctures of row generaly smaller than puncture diameter; punctures each with seta. Explanate margin

quite narrow, ended near posterior 0.20, with extremely fine, well separated serrations along entire margin; serrations

somewhat closer near apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin

elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an

equilateral triangle, posterior margin straight. Glabrous segments at apex only moderately produced. Segment 7

Western Hemisphere Hydraenidae

153

emarginate at apex. Legs: Profemur with small tubercle on inner surface at basal 0.50. Protibia arcuate in basal 0.50,

expanded on inner surface near apical 0.33. Metatrochanter with small tubercle. Metatibia gradually enlarged from

base to apex; basal 0.25 slightly arcuate. Genitalia: Aedeagus as illustrated (Fig. 46D)(2 examined).

Natural History. - The type-series was removed from leaves and other debris which had

become trapped behind rocks in a moderately large stream. This stream was in a pine-oak

transition area (Fig. 195B). Consocies included H. scintilla and H. cuspidicollis.

Distribution. - (Fig. 169). Known only from the type-locality at the base of the mountains

just north of the small village of Ixtlan de Juarez. This village is approximately 25 miles north

of the city of Oaxaca.

Etymology. - Latin-like noun in apposition, oaxaca, in reference to the type-locality.

54. Hydraena scolops new species

(Figs. 46C,169)

Type-locality. - Real de Arriba, Temescaltepec, Mexico, Mexico.

Type-specimen. - The holotype male (unique) is deposited in BMNH. This specimen was

collected by H. E. Hinton and R. L. Usinger in 1932.

Diagnosis. - Differentiated from other species in the leechi Group whose adults also lack a

pronotal scintilla, have a low ridge on the metasternum posterior to the mesosternal intercoxal

process, have a relatively broad intercoxal process, and have the elytral punctures in series, by

shape and size of the plaques, which are shaped as elongate triangles. The inner margins are

parallel, while the outer margins converge anteriorly so that the anterior extreme of each

plaque is acute. The plaques are separated by slightly less than the basal width of a plaque.

Males have a very small, pointed process on the posterior margin of the metatrochanter.

Description. — Form: Elongate-oval. Size: Holotype 1.48 mm long, 0.64 mm wide. Color: Head with dorsal surface

dark brown; labrum dark brown; maxillary palpi brown; antennae brown. Pronotum brown at anterior and posterior 0.50,

dark brown in center 0.50; sides slightly lighter than center. Elytra brown. Ventral surface dark brown except legs, elytral

epipleura and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width 0.36 mm. Frons moderately punctured,

most interstices slightly greater than puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus

microreticulate. Labroclypeal suture nearly straight across middle in dorsal aspect. Labrum bilobed, microreticulate, each

lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.26/0.12/0.20; palpomere 2 bent outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight in basal

0.33, arcuate in apical 0.66, median surface arcuate; apical segment widest near midlength. Mentum wider than long,

surface moderately shining, microreticulate. Submentum microreticulate. Genae shining; lateral area of each gena with

well developed foveola; posterior ridge absent. Postgena with microreticulation slightly larger than that of submentum.

Last five antennomeres pubescent. Eyes slightly less than 0.20 interocular distance in width. Thorax: Pronotum length at

midline 0.36 mm; maximum width (at approximately midlength) 0.48 mm; sides margined, denticulate; sides moderately

produced at middle, slightly arcuate and convergent to anterior angle, slightly sinuate and convergent to posterior; anterior

border 0.38 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle

0.50; posterior border 0.42 mm wide, slightly arcuate to rear. Posterointernal foveolae moderately developed; punctures in

foveola closer together than those on disc. Posteroexternal foveola delimited by very shallow depression with punctation

somewhat closer than that of disc. Interfoveolar depression slightly developed. Area between foveolae weakly elevated.

Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33

width of anterior region of pronotum. Transverse foveola slightly developed, with punctures closer together than punctures

on disc. Disc shining, punctures fine, separated by 0.50 puncture diameter near anterior and posterior borders by puncture

diameter or slightly greater in middle; punctures each with seta extended above cuticle in dry specimens. Scintilla absent.

Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina

sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median

carina extended to base of intercoxal process; intercoxal process relatively broad, sides nearly parallel, apex round, width

slightly less than distance between internal and median carinae. Metasternum with prominent ridge immediately posterior

to intprcoxal process; plaques well developed, triangular, medial surfaces parallel; plaques nearly 0.50 length of

metasternum in midline; greatest width of each plaque subequal to width of intercoxal process; plaques separated by

approximately greatest width of plaque; plaques flat in cross section. Elytra: Length 0.96 mm. Maximum width (at

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Perkins

Figs. 46A - D, Aedeagi of Hydraena holotypes. (A) H. crystallina. (B) H. mazamitla. (C) H. scolops. (D) H. oaxaca.

midlength) 0.64 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width slightly less than puncture diameter, as are interstices

between adjacent punctures of a row; punctures each with seta. Explanate margin quite narrow, ended near posterior

0.20, with extremely fine serrations near apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect,

elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment

flat, nearly an equilateral triangle, posterior margin straight. Glabrous segments at apex moderately produced. Segment

7 without emargination at apex. Legs: Profemur with minute tubercle on inner surface at midlength. Protibia expanded

on inner surface near apical 0.33. Metatrochanter with acute tubercle on posterior margin. Metatibia parallel sided in

Western Hemisphere Hydraenidae

155

apical 0.66. Genitalia: Aedeagus as illustrated (Fig. 46C)(1 examined).

Distribution. - (Fig. 169). Known only from the type-locality near Temescaltepec in the

state of Mexico, Mexico.

Etymology. - Greek, skolops (thorn). This name refers to the small, pointed process on the

hind margin of the metatrochanters.

55. Hydraena crystallina new species

(Figs. 46A,169)

Type-locality. - Seven miles S. Mazamitla, Jalisco, Mexico.

Type-specimens. - The holotype male and allotype with identical data are deposited in

USNM. These specimens were collected by my wife Maureen and I, July 15, 1974. Paratypes

consist of one male and two females (PDP) with same data as holotype plus five males and

eight females (CAS) collected by Hugh B. Leech at the type-locality, December 1, 1948.

Diagnosis. - Among those species of the leechi Group whose adults have an anterior median

ridge on the metasternum and have the mesosternal intercoxal process relatively broad, adults

of H. crystallina are distinguished by the plaques, which are narrow, non-elevated and

separated by more than twice the width of a plaque.

Description. — Form: Elongate. Size: Holotype 1 .38 mm long, 0.60 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and posterior

0.25, dark brown in middle 0.50; sides slightly lighter than center. Elytra brown. Ventral surface dark brown except legs,

elytral epipleura mentum and inflexed margin of pronotum testaceous. Head: Length 0.20 mm. Width 0.34 mm. Frons

moderately punctured, interstices equal to or slightly greater than puncture diameter; surface shining. Frontoclypeal

suture straight. Clypeus finely punctulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed; surface

punctulate; each lobe symmetrical arc; median emargination ended above midlength of labrum. Maxillary palpus with

following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.26/0.10/0.20; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface very

slightly arcuate; median surface evenly arcuate; palpomere 4 widest slightly past midlength. Mentum wider than long,

surface moderately shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of each gena with

well developed foveola; posterior ridge absent. Postgena with microreticulation slightly larger than that of submentum.

Last five antennomeres pubescent. Eyes slightly greater than 0.25 interocular distance in width. Thorax: Pronotum length

at midline 0.34 mm; maximum width (at approximately midlength) 0.48 mm; sides margined, denticulate; sides

moderately produced at middle, slightly arcuate and convergent to anterior angle, slightly sinuate and convergent to

posterior; anterior border 0.38 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate

to rear in middle 0.50; posterior border 0.42 mm wide, slightly arcuate to rear. Posterointernal foveolae weakly developed;

punctures in foveola closer together than those on disc. Posteroexternal foveola delimited by very shallow depression with

punctation somewhat closer than that of disc. Interfoveolar depression slightly developed. Area between external foveolae

slightly elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly

less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area somewhat

closer together than punctures on disc. Disc shining, punctures fine, separated by approximately puncture diameter;

punctures each with distinctive seta extended above cuticle in dry specimens. Scintilla absent, margin very slightly

produced in this area. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin,

median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from

anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively broad, sides nearly

parallel in apical 0.50, apex blunt, width at apex subequal distance between internal and median carinae. Metasternum

with ridge posterior to intercoxal process; plaques well developed, somewhat triangular, convergent slightly from posterior

to anterior; plaques 0.41 length of metasternum in midline; width of each plaque 0.33 width of intercoxal process at its

midlength; plaques separated posteriorly by approximately three times plaque width; plaques flat in cross section. Elytra:

Length 0.90 mm. Maximum width (at midlength) 0.60 mm. Surface shining, disc with 10 rows of punctures between

suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal to

-puncture diameter, as are interstices between adjacent punctures of a row; punctures each with seta. Explanate margin

quite narrow, ended near posterior 0.10, with extremely fine, well separated serrations along entire margin; serrations

somewhat closer near apices. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin

elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an

equilateral triangle, posterior margin straight. Glabrous segments at apex moderately produced. Segment 7 emarginate at

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Perkins

apex. Legs: Profemur with minute tubercle on inner surface near midlength. Protibia slightly expanded on inner surface

near apical 0.33. Metatibia slightly wider at middle than at apex. Genitalia: Aedeagus as illustrated (Fig. 46A)(7

examined).

Natural History. - Refer to H. scopula.

Distribution. - (Fig. 169). Known only from the type-locality near Mazamitla in the state of

Jalisco, Mexico.

Etymology. - Latin, crystallina (of crystal). Named in reference to the transparency of the

aedeagus.

56. Hydraena mazamitla new species

(Figs. 46B,169)

Type-locality. - Seven miles S. of Mazamitla, Jalisco, Mexico.

Type-specimens. - The holotype male and allotype with same data are deposited in CAS.

Hugh B. Leech collected these specimens, December 1, 1948.

Diagnosis. - Small size, about 1.36 mm long, moderately shiny pronotum, lack of a scintilla,

weakly elevated anteromedial ridge on the metasternum, and plaque form are the primary

differentiating external features of this species. The plaques are well developed, convergent

anteriorly, separated posteriorly by nearly twice plaque width, and rounded in cross-section.

The aedeagus (Fig. 46B) is very distinctive.

Description. — Form: Elongate. Size: Holotype 1.36 mm long, 0.60 mm wide. Color: Head with dorsal surface

brown, darker near eyes; labrum brown; maxillary palpi testaceous; antennae testaceous. Pronotum with brown macula on

disc, surrounding areas testaceous. Elytra brown. Ventral surface brown except legs, elytral epipleura and inflexed margin

of pronotum light brown. (This specimen appears to be slightly teneral.) Head: Length 0.20 mm. Width 0.34. Frons

moderately punctured, interstices equal to or slightly greater than puncture diameter; surface shining. Frontoclypeal

suture straight. Clypeus microreticulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate,

each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with

following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.24/0.12/0.18; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight in basal 0.33, arcuate in apical 0.66, median surface evenly arcuate; palpomere 4 widest slightly past midlength.

Mentum wider than long, surface shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of

each gena with well developed foveola; posterior ridge absent. Postgena with microreticulation slightly larger than that of

submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax:

Pronotum length at midline 0.32 mm; maximum width (at approximately midlength) 0.48 mm; sides margined,

denticulate; sides moderately produced at middle, slightly arcuate and slightly convergent to anterior angle, slightly

sinuate and convergent to posterior; anterior border 0.38 mm wide, straight and nearly perpendicular to midline in lateral

0.25; moderately arcuate to rear in middle 0.50; posterior border 0.42 mm wide, slightly arcuate to rear. Posterointernal

foveolae slightly developed; punctures in foveola closer together than those on disc. Posteroexternal foveola delimited by

very shallow depression with punctation somewhat closer than that of disc. Interfoveolar depression slightly developed.

Area between external foveolae weakly elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent

shaped, occupying slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed,

punctures in this area somewhat closer together than punctures on disc. Disc shining, punctures fine, separated by

puncture diameter near anterior and posterior borders, and by twice puncture diameter in middle; most punctures with

seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very

short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and

external carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal

process relatively narrow, sides nearly parallel, apex blunt, width at apex 0.66 distance between internal and median

carinae. Metasternum with median, anterior ridge; plaques well developed, triangular, convergent very slightly from

posterior to anterior; plaques nearly 0.50 length of metasternum in midline, greatest width of each plaque subequal to

width of intercoxal process; plaques separated posteriorly by slightly greater than plaque width; plaques slightly rounded in

cross section. Elytra: Length 0.84 mm. Maximum width (at midlength) 0.60 mm. Surface shining, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width

approximately equal to 0.50 puncture diameter, as are interstices between adjacent punctures of a row; punctures each

with a seta. Explanate margin quite narrow, ended near posterior 0.20, with extremely fine serrations near apices. Elytral

apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of

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157

angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous

segments at apex moderately produced. Segment 7 without emargination at apex. Legs: Profemur with tubercle on inner

surface near basal 0.33. Protibia slightly expanded on inner surface near apical 0.33. Mesotibia flattened on inner

surface near apex. Metatibia nearly parallel sided in apical 0.50. Genitalia: Aedeagus as illustrated (Fig. 46B)(1

examined).

Natural History. - Refer to Hydraena scopula.

Distribution. - (Fig. 169). Known only from the type-locality near Mazamitla, Jalisco,

Mexico.

Etymology. - Latin-like noun in apposition, mazamitla , in reference to the type-locality.

57. Hydraena prieto new species

(Figs. 42A,47A,169)

Type-locality. - One mile W. Los Bancos, Durango, Mexico.

Type-specimens. - The holotype male and allotype with same data are deposited in USNM.

My wife Maureen and I collected these specimens, July 17, 1974. Paratypes (29) are listed in

the appendix.

Diagnosis. - The metasternal plaques are very narrow, slightly elevated, and widely

separated, the distance being about five times the width of a plaque. Form of the plaques plus

the shiny, moderately sparsely punctate pronotum serve to distinguish H. prieto adults from

other members of the leechi Group which lack a scintilla and have the anteromedial region of

the metasternum elevated.

Description. — Form: Elongate. Size: Holotype 1.50 mm long, 0.66 mm wide. Color: Dorsal surface dark brown,

nearly black, except narrow brownish border around pronotum; maxillary palpi testaceous; antennae testaceous. Ventral

surface dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.22 mm. Width

0.40 mm. Frons finely and sparsely punctured, interstices two-three times puncture diameter; surface shining,

Frontoclypeal suture straight. Clypeus finely microreticulate, shiny. Labroclypeal suture arcuate when viewed from above.

Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of

labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.24/0.12/0.20;

palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4

with lateral surface nearly straight, median surface evenly arcuate; palpomere 4 widest near midlength. Mentum wider

than long; surface moderately shining, finely microreticulate. Submentum microreticulate. Genae shining; lateral area of

each gena with well developed foveola; posterior ridge absent. Postgena with microreticulation slightly larger than that of

submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax:

Pronotum length at midline 0.36 mm; maximum width (at approximately midlength) 0.54 mm; sides margined,

denticulate; sides moderately produced at middle, slightly arcuate and convergent to anterior angle, sinuate and

convergent to posterior; anterior border 0.44 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

moderately arcuate to rear in middle 0.50; posterior border 0.46 mm wide, slightly arcuate to rear. Posterointernal foveolae

moderately developed; punctures in foveola similar to those on disc. Posteroexternal foveola moderately developed, with

punctation somewhat closer than that of disc. Interfoveolar depression moderately developed. Area between external

foveolae weakly elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across

slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed. Disc shining, punctures fine,

separated by two-three times puncture diameter; punctures each with distinctive seta extended above cuticle in dry

specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly into very short spine; coxae separated by thin,

median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from

anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively broad, sides nearly

parallel; apex blunt, width at apex slightly less than distance between internal and median carinae. Metasternum with

ridge posterior to intercoxal process; plaques moderately developed, thin, very slightly carinate, convergent moderately

from posterior to anterior; plaques 0.50 length of metasternum in midline; width of each plaque 0.33 width of intercoxal

process at its midlength; plaques separated posteriorly by nearly four times plaque width; plaques located on sides of

median depression, therefore sloped toward midline. Elytra: Length 0.96 mm. Maximum width (at midlength) 0.66 mm.

Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most punctures

round; intervals not elevated, width approximately equal to puncture diameter or slightly greater, as are interstices

between adjacent punctures of a row; punctures each with a seta. Explanate margin quite narrow, ended near posterior

0.20, with extremely fine, well separated serrations near anterior angles and apices. Elytral apices, in dorsal aspect,

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gradually rounded; viewed posteriorly, elytral margin rises obliquely towards suture, forming an angle with opposite

elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous segments at apex

moderately produced. Segment 7 apparently not emarginate at apex (obscured by pubescence). Legs: Protibia expanded

on inner surface at apical 0.33. Mesotibia flattened on inner surface at apex. Metatibia gradually expanded from base

to apex. Genitalia: Aedeagus as illustrated (Fig. 47A)(19 examined).

Natural History. - The stream at the type-locality is rather rapid, flowing through a pine

forest. The beetles were taken at the sand-gravel margin, as were a few specimens of

Ochthebius mexcavatus. Adults of this species were also found in association with Hydraena

alternata, “ex under stones in a small creek in the mountains”.

Distribution. - (Figs. 42A,169). Found in the mountains of Durango and Jalisco, Mexico.

Etymology. - prieto, in reference to Prieto Mountain in the mountains of Durango near the

type-locality. The name also refers to the dark coloration of this species.

Remarks. - Los Bancos is a small village near the type-locality, which is about 100 miles

west of Durango, on highway MEX. 40.

58. Hydraena argutipes new species

(Figs. 47B,169)

Type-locality. - Two miles E. of Durango-Sinaloa boundary on highway MEX. 40, 7000

feet, Durango, Mexico.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. These specimens plus 10 paratypes (8 CAS; 2 PDP) from the same locality were

collected by D. E. Breedlove and J. F. Copp, December 30, 1962.

Diagnosis. - The metasternal plaques are well developed, have the lateral margins elevated

slightly, and are separated by slightly more than the width of a plaque. This feature, plus the

ochraceous legs and palpi serve to distinguish H. argutipes adults from those of other species of

the leechi Group which also lack a pronotal scintilla and have the anteromedial region of the

metasternum elevated.

Description. — Form: Elongate. Size: Holotype 1.46 mm long, 0.64 mm wide. Color: Dorsal surface dark brown,

nearly black, except narrow brownish border around pronotum; maxillary palpi testaceous, nearly yellow; antennae

testaceous. Ventral surface dark brown except legs, elytral epipleura, mentum and inflexed margin of pronotum,

brownish-orange. Head: Length 0.20 mm. Width 0.36 mm. Frons sparsely punctured, interstices twice puncture diameter;

surface shining. Frontoclypeal suture straight. Clypeus microreticulate. Labroclypeal suture arcuate when viewed from

above. Labrum bilobed, microreticulate, each lobe a symmetrical arc; median emargination ended at approximately

midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.28/0.12/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface slightly arcuate, median surface much more arcuate; apical segment widest

near midlength. Mentum wider than long, surface shining, finely microreticulate. Submentum microreticulate. Genae

shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with microreticulation

slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance

in width. Thorax: Pronotum length at midline 0.36 mm; maximum width (at approximately midlength) 0.50 mm; sides

margined, denticulate; sides moderately produced at middle, slightly arcuate and convergent to anterior angle, slightly

sinuate and convergent to posterior; anterior border 0.40 mm wide, straight and nearly perpendicular to midline in lateral

0.25, moderately arcuate to rear in middle 0.50; posterior border 0.44 mm wide, slightly arcuate to rear. Posterointernal

foveolae moderately developed; punctures in foveola closer together than those on disc. Posteroexternal foveola delimited

by very shallow depression with punctation somewhat closer than that of disc. Interfoveolar depression weakly developed.

Area between external foveolae weakly elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent

shaped, extended across slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed,

punctures in this area somewhat closer together than punctures on disc. Disc shining, punctures moderately fine, separated

by thin walls near anterior and posterior borders, and by puncture diameter or less in middle; many punctures with seta

extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as short spine;

coxae separated by thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external

carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process

Western Hemisphere Hydraenidae

Figs. 47A - D, Aedeagi of Hydraena holotypes. (A) H. prieto. (B) H. argutipes. (C) H. bractea. (D) H. bractoides.

Quaest. Ent., 1980, 16 (1,2)

160

Perkins

relatively broad, sides nearly parallel in apical 0.50, apex blunt, width at apex subequal to distance between internal

and median carinae. Metasternum with prominent ridge posterior to intercoxal process; plaques well developed,

somewhat triangular, remarkably reflective, medial margins parallel; plaques 0.50 length of metasternum in midline;

greatest width of each plaque 0.66 width of intercoxal process at its midlength; plaques separated posteriorly by slightly

less than twice plaque width; plaque lateral margin elevated, each plaque sloped toward midline. Elytra: Length

0.94 mm. Maximum width (at midlength) 0.64 mm. Surface shining, disc with 10 rows of punctures between suture

and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal to

puncture diameter, as are interstices between adjacent punctures of a row; punctures each with a seta. Explanate

margin narrow, ended near posterior 0.20, with extremely fine serrations near apices. Elytral apices, in dorsal aspect,

gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite

elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous segment at apex

moderately produced. Segment 7 emarginate at apex. Legs: Profemur with small tubercle on inner surface near

midlength. Protibia expanded on inner surface near apical 0.33. Mesotibia flattened on inner surface at apex. Metatibia

gradually expanded from base to apex. Genitalia: Aedeagus as illustrated (Fig. 47 B)(3 examined).

Distribution. - (Fig. 169). Known only from the type-locality in the mountains of Durango,

Mexico.

Etymology. - Latin, arguta (bright) plus ipes (foot). This name refers to the brightly

colored, ochraceous legs which contrast attractively with the dark brown dorsum and venter.

59. Hydraena brae tea new species

(Figs. 47C,169)

Type-locality. - Two miles E. of Durango-Sinaloa boundary on highway MEX. 40,

Durango, Mexico.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in CAS. One female paratype with same data is in PDP. These specimens were collected by D.

E. Breedlove and J. F. Copp, December 30, 1962.

Diagnosis. - The metasternal plaques of adults of this species are very distinctive due to

their large size and very smooth, extremely shiny surfaces. They lie on the sides of a shallow

median depression, occupying about 0.20 of the posterior part of the metasternum. Each plaque

is slightly wider than the distance separating them, much wider than the mesosternal process,

and tapers slightly anteriorly. The mesosternal process is very narrow, the width of its apex

being about 0.20 the distance separating the internal and median carinae. There is a sharp

elevated ridge on the metasternum posterior to the mesosternal process, and the pronotum lacks

a scintilla. Externally, H. bractea males are very similar to those of H. bractoides, but the

aedeagi are quite dissimilar (Figs. 47C-D). Refer to the diagnosis of H. bractoides for further

comments.

Description. — Form: Ovate. Size: Holotype 1.36 mm long, 0.64 mm wide. Color: Dorsal surface very dark brown,

nearly black, except anterior 0.25 and posterior 0.12 of pronotum brown. Maxillary palpi brown; antennae brown. Ventral

surface dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width

0.36 mm. Frons coarsely punctate, interstices less than puncture diameter; surface shining. Frontoclypeal suture straight.

Clypeus microreticulate. Labroclypeal suture straight in dorsal aspect. Labrum bilobed, microreticulate, each lobe

symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.24/0.12/0.16; palpomere 2 bent outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface arcuate in basal 0.25,

nearly straight in apical 0.75, median surface arcuate; palpomere 4 widest slightly past midlength. Mentum wider than

long, surface moderately shining, microreticulate. Submentum microreticulate. Genae shining; lateral area of each gena

with a well developed foveola; posterior ridge absent. Postgena with microreticulation similar to that of submentum. Last

five antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at

midline 0.36 mm; maximum width (at approximately midlength) 0.50 mm; sides margined, denticulate; sides moderately

produced at middle, slightly arcuate and slightly convergent to anterior angle, sinuate and rather markedly convergent to

posterior; anterior border 0.40 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate

to rear in middle 0.50; posterior border 0.42 mm wide, slightly arcuate to rear. Posterointernal foveolae well developed;

Western Hemisphere Hydraenidae

161

punctures in foveola closer together than those on disc, some confluent. Posteroexternal foveolae well developed, with

punctation closer than that of disc. Interfoveolar depression moderately developed. Area between external foveolae

moderately elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, occupying slightly

less than 0.33 width of anterior region of pronotum. Transverse foveola well developed. Disc dull, punctures of moderate

size and deeply impressed; interstices with surfaces somewhat uneven varied from thin walls to puncture diameter; most

punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina

produced anteriorly as very short spine: coxae separated by thin, median carina; carina a sinuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina continued to base

of intercoxal process; intercoxal process extremely narrow, sides tapered, apex somewhat carinate, width at apex 0.20

distance between internal and median carinae. Metasternum with median keel posterior to intercoxal process; plaques

markedly developed, straight, median margins parallel; plaques 0.54 length of metasternum in midline; width of each

plaque four-five times width of intercoxal process at its apex; plaques separated by approximately 0.66 plaque width;

plaques highly reflective. Elytra: Length 0.92 mm. Maximum width (at midlength) 0.64 mm. Surface shining, disc with

10 rows of punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not

elevated, width approximately equal to 0.50 puncture diameter, as are interstices between adjacent punctures of a row;

each puncture with a seta. Explanate margin moderately developed, ended near apices, without perceptible serrations

along margin. Elytral apices, in dorsal aspect, gradually rounded; in posterior aspect, elytral margin not elevated

obliquely toward suture, not in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an

equilateral triangle, posterior margin straight. Glabrous segments at apex missing from specimen. Legs: Protibia

arcuate; apical 0.33 expanded on inner surface. Metatrochanter with carina. Metafemur broad, lateral surface arcuate,

medial surface sinuate. Metatibia arcuate; apical 0.50 expanded. Genitalia: Aedeagus as illustrated (Fig. 47C)(1

examined).

Distribution. - (Fig. 169). Known only from the type-locality in the mountains of Durango,

Mexico.

Etymology. - Latin, bractea (thin metal plate, gold leaf). This name refers to the smooth,

very reflective plaques.

60. Hydraena bractoides new species

(Figs. 47D,169)

Type-locality. - 24 miles W. La Ciudad, Durango, Mexico.

Type-specimens. - The holotype male (unique) is deposited in CNC. This specimen was

collected by H. F. Howden, June 15, 1964.

Diagnosis. - H. bractoides adults are very similar to those of H. bractea in habitus

appearance and form of the metasternal plaques (refer to the diagnosis of H. bractea for a

description of the plaques). Additionally, they share the following features: (1) absence of a

pronotal scintilla, (2) very thin mesosternal process, its width being about 0.20 the distance

separating the internal and median carinae, and (3) presence of an anteromedial ridge on the

metasternum. H. bractoides adults differ from those of H. bractea in their more deeply

impressed posterointernal foveolae, less rounded elytral sides, and, in males, the more strongly

expanded hind tibiae. These differences are very minor indeed when compared to the

differences in aedeagi (Figs. 47C-D).

Description. — Form: Ovate. Size: Holotype 1.34 mm long, 0.60 mm wide. Color: Dark brown. Head: Length

0.24 mm; width 0.34 mm. Frons coarsely punctate; interstices equal to or less than puncture diameter; shining.

Frontoclypeal suture arcuate. Clypeus finely punctulate in middle, microreticulate laterally. Labroclypeal suture straight.

Labrum bilobed, microreticulate; median emargination ending at about midlength. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.20/ 0.10/0.14; palpomere 4 with medial surface more markedly

arcuate than lateral. Mentum width equal length, moderately shiny, finely microreticulate. Submentum microreticulate.

Genae shiny, lateral area of each gena with well developed foveola; posterior ridge absent. Postgena microreticulate.

Thorax: Pronotum length at midline 0.34 mm; maximum width (slightly before midlength) 0.48 mm; sides margined,

denticulate, moderately produced at middle, slightly arcuate and slightly convergent to anterior angles, sinuate and rather

markedly convergent to posterior angles; anterior border 0.38 mm wide, straight and nearly perpendicular to midline in

lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.40 mm wide, slightly arcuate to rear.

Posterointernal foveolae well developed, deep; punctures in foveola closer together than those on disc, some confluent.

Quaest. Ent., 1980, 16 (1,2)

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Perkins

Posteroexternal foveolae well developed, punctation similar to that on disc. Interfoveolar depression moderately

developed. Area between external foveolae moderately elevated. Anteroexternal foveolae well developed, each extended

slightly less than 0.33 width of anterior region of pronotum. Transverse foveola well developed, punctures closer

together than those on reliefs. Disc moderately dull, densely, moderately coarsely punctate, most punctures with

distinctive seta; interstices shiny. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine;

coxae separated by thin median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external

carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process

narrow, carinate, width at apex 0.33 distance between internal and median carinae. Metasternum with low median

carina behind intercoxal process; plaques large, parallel, very shiny, in slight depression; each plaque width three times

that of intercoxal process, length 0.60 that of metasternum in midline; plaques separated by 0.66 plaque width. Elytra:

Length 0.88 mm. Maximum width (at midlength) 0.60 mm. Surface dull, disc with 10 rows of punctures between

suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width about equal to 0.50

puncture diameter, as are interstices between adjacent punctures of a row; each puncture with an indistinct seta.

Explanate margin rather well developed, ended near apices, without perceptible serrations along margin. Elytral apices,

in dorsal aspect, gradually rounded; in posterior aspect, elytral margin not elevated obliquely toward suture, not in form

of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle, posterior margin

straight. Glabrous segments at apex not distinctively produced. Legs: Protibia arcuate, apical 0.33 expanded on inner

surface. Metafemur moderately broad, lateral surface arcuate, median surface sinuate. Metatibia arcuate, apical 0.50

expanded. Genitalia: Aedeagus as illustrated (Fig. 47D)(1 examined).

Distribution. - (Fig. 169). Known only from the type-locality near La Ciudad in the state of

Durango, Mexico.

Etymology. - Latin, bractoides , in reference to the similarity to Hydraena bractea.

61. Hydraena cuspidicollis new species

(Figs. 42A,45 A,48 A-I,6 1 E-H, 1 69)

Type-locality. - One mile N. Ixtlan de Juarez, Oaxaca, Mexico.

Type-specimens. - The holotype male and allotype with identical data are deposited in

USNM. My wife Maureen and I collected these specimens, July 5, 1974. Paratypes (72) are

listed in the appendix.

Diagnosis. - Immediately distinguished from adults of other Western Hemisphere

Hydraena by the broad, depressed body form and pronotal shape, with anterior angles

produced (Figs. 48 A, C).

Description. — Form: Ovate. Size: Holotype 1.60 mm long, 0.80 mm wide. Color: Dorsal surface dark brown,

except pronotum with faint testaceous border. Maxillary palpi testaceous; antennae testaceous. Ventral surface dark

brown except legs, elytral epipleura and inflexed margin of pronotum orange-brown. Head: Length 0.20 mm. Width

0.42 mm. Frons moderately punctured, interstices equal to or slightly greater than puncture diameter; surface moderately

shining, setae quite prominent. Frontoclypeal suture straight. Clypeus finely punctulate. Labroclypeal suture nearly

straight across middle in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination

ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4,

respectively; 0.24/0.10/0.16; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not

especially expanded; palpomere 4 with lateral surface nearly straight, median surface arcuate; palpomere 4 widest near

midlength. Mentum wider than long, surface moderately shining, finely microreticulate. Submentum microreticulate.

Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with punctation

similar to that of submentum. Last five antennomeres pubescent. Eyes 0.20 interocular distance in width. Thorax:

Pronotum length at midline 0.36 mm; maximum width (at approximately midlength) 0.62 mm; sides with furrow,

denticulate at sides, upper surface finely, extremely densely punctured; rather markedly produced at middle, slightly

arcuate and slightly convergent to anterior angle, markedly sinuate and markedly convergent to posterior; anterior border

0.48 mm wide, angles produced anteriorly, lateral 0.20 arcuate to rear, in form of recessed area, receptacle for posterior

margin of eye, middle 0.60 slightly arcuate to rear; posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal

foveolae markedly developed; punctures in foveola similar to those on disc. Posteroexternal foveola well developed, with

punctation somewhat less distinct than that of disc. Interfoveolar depression moderately developed. Area between external

foveolae well elevated. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, occupying 0.33

width of anterior region of pronotum. Transverse foveola moderately developed, with punctures somewhat closer together

than punctures on disc. Disc shining, punctures moderately large and deeply impressed, separated by puncture diameter;

most punctures with distinctive seta extended above cuticle in dry specimens, scintilla absent. Prosternum carinate, carina

Western Hemisphere Hydraenidae

163

Figs. 48 A - I, Hydraena cuspidicollis, 9. (A) dorsal habitus. (B) ventral habitus. (C) pronotum (arrows indicate pronotal

sensilla). (D) metasternum (arrow indicates ridge posterior to intercoxal process). (E) head, ventral aspect. (F) labrum,

dorsal aspect. (G) protibia. (H) pro- and mesosternum. (1) detail of inflexed pronotal margin.

Quaest. Ent., 1980, 16 (1,2)

164

Perkins

produced anteriorly as very short spine; coxae separated from median carina by thin shelf; carina sinuate line in lateral

aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to

base of intercoxal process; intercoxal process relatively broad, sides nearly parallel, apex blunt, width at apex 0.66

distance between internal and median carinae. Metasternum with median ridge posterior to intercoxal process; plaques

well developed, somewhat triangular, nearly parallel; plaques 0.41 length of metasternum in midline; greatest width of

each plaque subequal to width of intercoxal process; plaques separated posteriorly by approximately twice plaque width;

plaques on sides of median depression, sloped toward midline. Elytra: Length 1.08 mm. Maximum width (at midlength)

0.80 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite regular; most

punctures round; intervals not elevated, width slightly greater than puncture diameter, interstices between adjacent

punctures of row generally smaller than puncture diameter; each puncture with seta. Explanate margin relatively broad,

extended nearly to apices, with fine serrations near anterior angles. Elytral apices, in dorsal aspect, gradually rounded;

in posterior aspect, elytral margin elevated extremely slightly, obliquely toward suture, in form of slight angle with

opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle, posterior margin arcuate. Glabrous

segments at apex slightly produced. Segment 7 without emargination at apex. Legs: Protibia arcuate, enlarged in apical

0.50. Metatrochanter with small tubercle. Metatibia arcuate in basal 0.50, enlarged and with brush of hairs in apical

0.50 (Figs. 61E-H). All tarsi with prominent setae. Genitalia: Aedeagus as illustrated (Fig. 45A)(3 examined).

Natural History. - Refer to Hydraena scintilla for notes concerning the type-locality. Refer

also to the natural history notes of Hydraena scopula and Spanglerina ingens.

Distribution. - (Figs. 42A,169). Central Mexico, in the states of Jalisco, Nayarit, Mexico,

Veracruz and Oaxaca.

Etymology. - Latin, cuspidis (pointed end) plus collis (neck). This epithet refers to the

produced anterior angles of the pronotum.

Remarks. - Of the 73 specimens known to date, only three are males.

The marginicollis Group

Adults of marginicollis Group are quite similar to those of the lee chi Group in many

respects, but lack the posterointernal foveolae of the pronotum seen in the latter.

Many species in this group are comprised of quite small members that are very similar to

one another externally. The aedeagi, however, are very complex in many instances, and

generally differ greatly between species.

The group is very widespread, found from northern Argentina to the southern United States

(Fig. 160).

The marginicollis Subgroup

Adults of species included in the marginicollis Subgroup have the procoxae separated by a

thin carina and the mesosternal process is relatively narrow compared to that of adults of the

geminya Subgroup (cf. Figs. 54B,I,63A-B,F). Except for a very few species, such as H.

anisonycha , H. d-destina and H. barricula, the metatibiae of males are unmodified. Male

protibiae, however, are usually modified in some manner, generally with an excavation on the

inner surface near the apex (Figs. 54G-H). Males of many species have the last abdominal

segments greatly produced (e.g. Fig. 63B).

Many of the species included in this subgroup are small and very similar to one another

externally. The aedeagus, however, shows remarkable differences between species, and should

be examined when members of this Subgroup are studied. The species complexes used herein

are based upon aedeagal affinities. Most of these complexes are quite consistent with

biogeographical data (see section on phylogeny).

Western Hemisphere Hydraenidae

165

The marginicollis Subgroup, which currently consists of 30 species, ranges from the eastern

United States south through Mexico, Central America and the Antilles to northern Argentina.

The greatest species diversity is in the mountains of southern Mexico (Chiapas) and

Guatemala, where eight species are found. This statistic should be viewed with some scepticism,

however, since this geographical area has seen more specialized collecting than some other

areas, especially the highlands of South America.

The mexicana Complex

62. Hydraena tucumanica new species

(Figs. 49A,170)

Type-locality. - 20 kilometers S. Tucuman, Tucuman Province, Argentina.

Type-specimens. - The holotype male, allotype and one female paratype, all with identical

locality data, are deposited in USNM. Paul and Phyllis Spangler collected these specimens,

May 23, 1969.

Diagnosis. - The aedeagus must be used to reliably distinguish H. tucumanica males from

those of other species of the marginicollis Subgroup which also have serial elytral punctures

and small oval plaques.

Description. — Form: Elongate. Size: Holotype 1.40 mm long, 0.60 mm wide. Color: Dorsum of head black;

pronotum brown at margins, diffuse black macula on disc; elytra brown. Venter dark brown, nearly black. Legs with basal

0.50 of femur brown, remainder testaceous. Maxillae, antennae, inflexed margin of pronotum, and elytral epipleura

testaceous. Head: Length 0.22 mm; width 0.36 mm. Frons closely, moderately coarsely punctate, punctures separated by

about 0.50 puncture diameter, interstices shiny. Frontoclypeal suture slightly arcuate. Clypeus punctate in midline,

microreticulate laterally. Labroclypeal suture straight. Labrum bilobed, microreticulate, median emargination ended at

about midlength. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4 respectively: 0.22/0.10/0.18;

palpomere 4 asymmetrical, widest near distal 0.33. Mentum width equal length, densely, finely punctulate. Submentum

microreticulate. Genae shiny, foveolate laterally; posterior ridge absent. Postgena microreticulate. Thorax: Pronotum

length at midline 0.36 mm; maximum width (at midlength) 0.46 mm; sides margined, denticulate, slightly produced at

middle, slightly arcuate and slightly convergent to anterior angles, very slightly sinuate and slightly convergent to posterior

angles; anterior border 0.38 mm wide, straight and nearly perpendicular to midline in lateral 0.17, moderately arcuate to

rear in middle 0.66; posterior border 0.42 mm wide, very slightly arcuate to rear. Posterointernal foveolae absent.

Posteroexternal foveolae extremely shallow, nearly imperceptible. Interfoveolar depression shallow. Anteroexternal

foveolae well developed, each somewhat crescent shaped, extended across 0.25 width of anterior region of pronotum.

Transverse foveola absent. Disc moderately shiny, densely, deeply, moderately coarsely punctate, most punctures

separated by less than puncture width; each puncture with fine seta. Scintilla absent. Prosternum carinate, coxae separated

by thin carina, carina sinuate in lateral view. Mesosternum with internal and external carinae divergent from anterior to

posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow, apex blunt, width at

apex 0.50 distance between internal and median carinae. Metasternum with small oval plaques at posterior 0.20. Elytra:

Length 0.88 mm. Maximum width (at midlength) 0.60 mm. Disc moderately shiny, with 10 slightly irregular rows of deep,

moderately large punctures between suture and humeral callus; intervals not elevated, width about 0.50 puncture width;

interstices between punctures of row about 0.25 puncture width; each puncture with seta. Explanate margin narrow, ended

near posterior 0.20. Elytral border very finely serrate. Elytral apices slightly truncate in dorsal view; in posterior aspect

elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat,

nearly an equilateral triangle, posterior margin straight. Glabrous segments at apex produced. Tergum 7 emarginate at

apex. Legs: Protibia slightly arcuate, gradually increased in size from base to apex. Other legs without apparent

modification, slender. Genitalia: Aedeagus as illustrated (Fig. 49A)(1 examined).

Distribution. - (Fig. 170). Known only from the type-locality near Tucuman, Tucuman

Province, Argentina.

Etymology. - Latin, tucumanica , in reference to the known distribution.

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Perkins

63. Hydraena quechua new species

(Figs. 49B,50B,170)

Type-locality. - Babahoyo, Los Rios Province, Ecuador.

Type-specimens. - The holotype male and allotype with identical data are deposited in

USNM. Paratypes (8 males, 7 females) from the same locality, collected by A. Langley and J.

Cohen, June 21, 1975, are deposited in USNM and PDP. Additional paratypes (10 males, 11

females) are deposited in USNM: 5.5 miles N. Nobel, Guayas Province, Ecuador, January 12,

1978, P. J. Spangler collector.

Diagnosis. - Readily distinguished from Hydraena jivaro, the only other Hydraena now

known from Ecuador, by smaller size (1.22 vs 1.48 mm) and black labrum of its adults. The

labrum of Hydraena jivaro is testaceous. The aedeagus must be studied to reliably distinguish

males of Hydraena quechua from other similarly sized and sculptured members of the

marginicollis Subgroup.

Description. — Form: Elongate. Size: Holotype 1.22 mm long, 0.54 mm wide. Color: Dorsum with labrum, clypeus

and frons black; pronotum with transverse black macula occupying area from anterior 0.28 to posterior 0.14, remainder

testaceous; elytra brown. Venter dark brown. Legs with basal 0.50 of femur brown, remainder testaceous. Maxillae,

inflexed. margin of pronotum, and elytral epipleura testaceous. Head: Length 0.20 mm; width 0.32 mm. Frons moderately

punctate, most punctures separated by puncture diameter, interstices shiny. Frontoclypeal suture slightly arcuate. Clypeus

shiny in midline, microreticulate and dull laterally. Labroclypeal suture straight. Labrum bilobed, median emargination

ending at midlength, microreticulate. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4 respectively:

0.22/0.10/0.16; palpomere 4 asymmetrical, greatest width near apical 0.33. Mentum width equal length, shiny, finely

punctulate. Submentum microreticulate. Genae shiny, foveolate laterally; posterior ridge absent. Postgena microreticulate.

Thorax: Pronotum length at midline 0.30 mm; maximum width (at midlength) 0.42 mm; sides margined, denticulate,

slightly produced at middle, slightly sinuate and slightly convergent to posterior angles; anterior border 0.36 mm wide,

straight and nearly perpendicular to midline in lateral 0.17, moderately arcuate to rear in middle 0.66; posterior border

0.38 mm wide, very slightly arcuate to rear. Posterointernal foveolae absent. Posteroexternal foveolae extremely shallow,

nearly imperceptible. Interfoveolar depression very shallow. Anteroexternal foveolae well developed, each somewhat

crescent shaped, extended across about 0.25 width of anterior region of pronotum. Transverse foveola absent. Disc shiny,

punctures slightly elongate, separated by puncture diameter near anterior and posterior borders, by twice this distance in

middle; punctures without apparent setae. Scintilla absent. Prosternum carinate; coxae separated by thin median carina,

carina sinuate line in lateral view. Mesosternum with internal and external carinae divergent from anterior to posterior;

median carina extended to base of intercoxal process; intercoxal process relatively narrow, apex blunt, width at apex 0.50

distance between internal and median carinae. Metasternum with well developed parallel plaques, separated by about

three times plaque width, 0.33 length of metasternum; each plaque about as wide as apex of intercoxal process. Elytra

Length 0.78 mm. Maximum width (at midlength) 0.54 mm. Disc shiny, with 10 rows of moderate sized punctures between

suture and humeral callus; intervals not elevated, width slightly less than puncture width, as are interstices between

punctures of a row; punctures with very fine seta. Explanate margin slightly developed, ended near posterior 0.20. Elytral

border from posterior 0.20 to apices finely serrate. Elytral apices somewhat truncate in dorsal view; viewed posteriorly,

elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat,

nearly an equilateral triangle, posterior margin straight. Glabrous segments at apex produced. Tergum 7 emarginate at

apex. Legs: Protibia slightly arcuate, increased gradually in size from base to apex. Other legs slender, apparently

unmodified. Genitalia: Aedeagus as illustrated (Fig. 49B)( 10 examined).

Natural History. - The specimens from Babahoyo were taken at ultraviolet light and most

are teneral, indicating pupation occurs in June, at least. The specimens from Nobol were

collected from a roadside pool (January).

Distribution. - (Figs. 50B,170). Presently known from Los Rios and Guayas Provinces,

Ecuador.

Etymology. - Noun in apposition, Latin in form, in reference to the Quechua Indians of

Ecuador.

Figs. 49A - D, Aedeagi of Hydraena holotypes. (A) H. tucumanica. (B) H. quechua. (C) H. limpidicollis. (D) H.

newtoni.

64. Hydraena limpidicollis new species

(Figs. 49C,170)

Quaest. Ent., 1980, 16 (1,2)

168

Perkins

Type-locality. - Rio Frijoles, 4.1 miles NW Gamboa, Canal Zone, Panama.

Type-specimens. - The holotype male and allotype with identical data are deposited in

USNM. Paratypes (6 males, 7 females) from same locality are deposited in MCZ, USNM and

PDP. These specimens were collected by A. F. Newton, February 19, 1976.

Diagnosis. - Testaceous pronotum, small size, metasternal depression shape and aedeagus

serve as diagnostic features. Adults differ from those of Hydraena newtoni, the only other

species characterized by a testaceous pronotum, by the unicolorous elytra, smaller size, smaller

metasternal depression and aedeagal form.

Description. — Form: Ovate. Size: Holotype 1.00 mm long, 0.48 mm wide. Color: Pronotum testaceous, contrasting

markedly with dark brown head and elytra; legs, maxillae, deflexed margin of pronotum and elytral epipleura testaceous;

venter dark brown. Head: Length 0.18 mm; width 0.28 mm. Frons finely sparsely punctate, interstices one-two times

puncture diameter, shining. Frontoclypeal suture straight. Clypeus transversely depressed, shiny in middle, microreticulate

laterally. Labroclypeal suture arcuate. Labrum bilobed, median emargination ended at about midlength. Maxillary palpus

with following lengths (mm) of palpomeres 2, 3 and 4 respectively: 0.18/0.06/0.14; palpomere 4 very slightly

asymmetrical. Mentum wider than long, shiny, very finely punctulate. Submentum shiny, finely sparsely punctulate.

Genae shiny, foveolate laterally; posterior ridge absent. Postgena microreticulate. Thorax: Pronotum length at midline

0.24 mm; maximum width (at midlength) 0.34 mm; sides margined, denticulate, straight in middle, arcuate to anterior

angles, slightly sinuate to posterior angles; anterior border 0.30 mm wide, straight and nearly perpendicular to midline in

lateral 0.17, slightly arcuate to rear in middle 0.66; posterior border 0.30 mm wide, slightly arcuate to rear. Posterointernal

and posteroexternal foveolae absent. Anteroexternal foveolae well developed, crescent shaped, each occupying about 0.25

width of anterior region of pronotum. Transverse foveola absent. Disc shiny, finely, moderately sparsely punctate. Scintilla

absent. Prosternum carinate; coxae separated from carina by very thin shelf; carina sinuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina absent; intercoxal

process broad, width at apex equal distance between internal carina and midline. Metasternum with triangular depression

extended across posterior 0.50 in midline; plaques small, thin, on sides of triangular depression. Elytra: Length 0.62 mm.

Maximum width (at midlength) 0.48 mm. Disc shiny, with 10 indistinct rows of shallow punctures between suture and

humeral callus; intervals not elevated, width one-two times puncture diameter, like interstices between punctures of row;

punctures with very fine seta. Explanate margin narrow, ended near posterior 0.20; without apparent serrations. Elytral

apices, in dorsal aspect, rounded; in posterior aspect, elytral margin not elevated obliquely toward suture, not in form of

angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle; posterior margin straight.

Glabrous segments not produced. Legs: Protibia very slightly arcuate, other legs apparently unmodified, very slender.

Genitalia: Aedeagus as illustrated (Fig. 49C)(7 examined).

Natural History. - These specimens were extracted (using a Berlese funnel) from wet leaves

and flood debris collected at the margin of the Rio Frijoles.

Distribution. - (Fig. 170). Known only from the type-locality near Gamboa in the Canal

Zone, Panama.

Etymology. - Latin, limpid (transparent) plus collis (neck). Specimens of Hydraena

limpidicollis, when in alcohol, have the pronotum very transparent, so much so that the front

legs and posterior part of the head are visible through the marginal areas. The pronotum

becomes more opaque upon drying.

65. Hydraena newtoni new species

(Figs. 49D,170)

Type-locality. - Rio Frijoles, 4.1 miles NW Gamboa, Canal Zone, Panama.

Type-specimens. - The holotype male and allotype with identical data are deposited in

USNM. Paratypes (6 males, 10 females) from same locality are deposited in MCZ, USNM,

and PDP. These specimens were collected by A. F. Newton, February 19, 1976.

Diagnosis. - Distinguished from all Western Hemisphere Hydraena , except Hydraena

limpidicollis, by the testaceous pronotum; differs from the latter by (1) slightly larger size, (2)

presence of a diffuse light brown area on elytral disc, (3) broader, deeper, U-shaped

metasternal depression, (4) presence of a protibial tooth in males, and (5) aedeagal form

Western Hemisphere Hydraenidae

169

(Fig. 49D).

Description. — Form: Ovate. Size: Holotype 1.12 mm long, 0.50 mm wide. Color: Pronotum testaceous, head and

elytra dark brown except for diffuse light brown area on disc; venter dark brown; legs, palpi, mentum and apex of abdomen

testaceous. Head: Length 0.20 mm; width 0.29 mm. Frons finely moderately sparsely punctate, interstices 0. 5-2.0 times

puncture diameter, shining. Frontoclypeal suture straight. Clypeus transversely depressed, shiny in middle, microreticulate

laterally. Labroclypeal suture arcuate. Labrum bilobed, median emargination ended at about midlength. Maxillary palpus

with following lengths (mm) of palpomeres 2, 3 and 4 respectively: 0.19/ 0.08/0.16; palpomere 4 very slightly

asymmetrical. Mentum wider than long, shiny, very finely punctulate. Submentum shiny, finely sparsely punctulate.

Genae shiny, foveolate laterally; posterior ridge absent. Postgena microreticulate. Thorax: Pronotum length at midline

0.30 mm; maximum width (at midlength) 0.35 mm; sides margined, denticulate, parallel just before middle, arcuate to

anterior angles, slightly sinuate and convergent to posterior angles; anterior border 0.32 mm wide, straight and nearly

perpendicular to midline in lateral 0.17, slightly arcuate to rear in middle 0.66; posterior border 0.33 mm wide, slightly

arcuate to rear. Posterointernal and posteroexternal foveolae absent. Anteroexternal foveolae well developed, cresent

shaped, each extended across about 0.25 width of anterior region of pronotum. Transverse foveola absent. Disc shiny,

finely, moderately sparsely punctate. Scintilla absent. Prosternum carinate; coxae separated from carina by very thin shelf;

carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior;

median carina absent; intercoxal process broad, width at apex equal distance between internal carina and midline.

Metasternum with deep, wide U-shaped depression extended across posterior 0.50 in midline; plaques small, thin, at border

of U-shaped depression. Elytra: Length 0.70 mm; maximum width (at midlength) 0.50 mm. Disc moderately convex,

shiny, with 10 indistinct rows of shallow punctures between suture and humeral callus; intervals not elevated, width

one-two times puncture diameter as are interstices between punctures of row; punctures with very fine but quite evident

seta. Explanate margin narrow, ending near posterior 0.20; without apparent serrations. Elytral apices, in dorsal aspect,

rounded; viewed posteriorly, elytral margin not elevated obliquely toward suture, not in form of angle with opposite

elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle; posterior margin straight. Glabrous segments

not produced. Legs: Protibia slightly arcuate, inner surface slightly enlarged and with tooth near apical 0.33; other legs

very slender, apparently unmodified. Genitalia: Aedeagus as illustrated (Fig. 49D)(7 examined).

Natural History. - These specimens were extracted (using a Berlese funnel) from wet leaves

and flood debris collected at the margin of the Rio Frijoles. Also found in this material were

specimens of Hydraena limpidicollis and H. pontequula.

Distribution. - (Fig. 170). Known only from the type-locality near Gamboa in the Canal

Zone, Panama.

Etymology. - I am pleased to dedicate this attractive and unusual new species to Alfred F.

Newton, Jr., who collected the only specimens known to date.

66. Hydraena guatemala new species

(Figs. 51A,170)

Type-locality. - 17 miles E. Escuintla, Escuintla, Guatemala.

Type-specimen. - The holotype male (unique) is deposited in USNM. Paul J. Spangler

collected this specimen, July 8, 1965.

Diagnosis. - The aedeagus should be used to distinguish Hydraena guatemala males from

those of other species of the marginicollis Subgroup which also have small oval plaques and are

relatively small in body length (about 1.26 mm).

Description. — Form: Elongate Size: Holotype 1 .26 mm long, 0.52 mm wide. Color: Head with dorsal surface dark

brown, nearly black; labrum dark brown; maxillary palpi and antennae testaceous. Pronotum testaceous at anterior and

posterior 0.20, dark brown in middle 0.60; sides slightly lighter than disc. Elytra brown. Ventral surface dark brown except

legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.18 mm. Width 0.34 mm. Frons moderately

punctate, interstices equal to or slightly less than puncture diameter; surface shining. Frontoclypeal suture straight.

Clypeus microreticulate at sides, shiny in middle. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.24/0.10/0.16; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface slightly

arcuate, median more markedly arcuate; palpomere 4 widest near apical 0.33. Mentum wider than long, surface shining,

finely and sparsely punctulate. Submentum finely, rather sparsely punctulate. Genae shining; lateral area of each gena

with well developed foveola; posterior ridge absent. Postgena with punctation slightly larger than that of submentum. Last

Quaest. Ent., 1980, 16 (1,2)

170

Perkins

Figs. 50A - B, Geographical distributions. (A) Gymnochthebius peruvianus • , G. bartyrae ★ and Parhydraenida

pentatenkta ■ . (B) Hydraena quechua • , H. premordica ★ , H. jivaro A and H. anisonycha ■ .

five antennomeres pubescent. Eyes slightly less than 0.33 interocular distance in width. Thorax: Pronotum length at

midline 0.32 mm; maximum width (at approximately midlength) 0.42 mm; sides margined, denticulate; sides relatively

slightly produced at middle, straight and very slightly convergent to anterior angle, very slightly concave and slightly

convergent to posterior; anterior border 0.38 mm wide, straight and nearly perpendicular to midline in lateral 0.25,

moderately arcuate to rear in middle 0.50; posterior border 0.40 mm wide, slightly arcuate to rear. Posterointernal

foveolae absent. Posteroexternal foveola absent. Interfoveolar depression absent. Anteroexternal foveolae well developed,

each foveola somewhat crescent shaped, extended across slightly less than 0.33 width of anterior region of pronotum.

Transverse foveola absent. Disc shining, punctures fine, separated by one-three times puncture diameter; most punctures

with seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as

very short spine; coxae separated by thin, median carina, latter sinuate line in lateral aspect. Mesosternum with internal

and external carinae divergent from anterior to posterior ; median carina extended to base of intercoxal process;

intercoxal process relatively narrow, sides tapered, apex blunt, width at apex 0.33 distance between internal and median

carinae. Metasternum with plaques slightly developed, of small ovals at posterior 0.20; width of each plaque subequal to

width of intercoxal process at its apex; plaques separated posteriorly by approximately twice plaque width; plaques flat

in cross section. Elytra: Length 0.78 mm. Maximum width (at midlength) 0.52 mm. Surface shining, disc with 10 rows

of punctures between suture and humeral callus; most punctures round; intervals not elevated; width approximately

equal to puncture diameter, as are interstices between adjacent punctures of row; each puncture with seta. Explanate

margin quite narrow, ended near posterior 0.20, with fine serrations in posterior 0.33; serrations closer near apices.

Elytral apices, in dorsal aspect, truncate; in posterior aspect, elytral margin extended obliquely toward suture, in form

of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous

segments at apex moderately produced. Segment 7 emarginate at apex. Legs: Profemur with minute tubercle on inner

surface near midlength. Protibia enlarged gradually from base to apex, slightly arcuate, very slightly expanded on inner

surface near base. Metatibia nearly parallel sided in apical 0.66. Genitalia: Aedeagus as illustrated (Fig. 5 1 A)( 1

examined).

Distribution. - (Fig. 170). Presently known only from the type-locality near Escuintla,

Guatemala.

Etymology. - Noun in apposition, Latin in form, guatemala, in reference to the known

distribution.

Western Hemisphere Hydraenidae

171

67. Hydraena haitensis new species

(Figs. 5 IB, 170)

Type-locality. - Etang Lachaux, SW peninsula, under 1000 feet, Haiti.

Type-specimen. - The holotype male (unique) is deposited in MCZ. P.J. Darlington

collected this specimen, October 26-27 , 1934.

Diagnosis. - The geographical distribution (Haiti), small size (about 1.28 mm), and

moderately developed plaques, which are separated by the greatest width of a plaque, are of

some aid in assigning specimens to this species. The aedeagus must be used to reliably

distinguish males of this species from others in the marginicollis Subgroup which are of

approximately the same body size and plaque configuration.

Description. — Form: Elongate. Size: Holotype 1.28 mm long, 0.52 mm wide. Color: Head with dorsal surface dark

brown, nearly black; labrum dark brown; maxillary palpi brown; antennae brown. Pronotum dark brown, nearly black,

except for narrow, testaceous border at anterior and posterior margins. Elytra brown. Ventral surface dark brown except

legs, elytral epipleura, apex of abdomen and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width 0.34 mm.

Frons moderately punctured, interstices equal to or slightly greater than puncture diameter; surface shining. Frontoclypeal

suture straight. Clypeus finely microreticulate at sides, shining in midline. Labroclypeal suture arcuate in dorsal aspect.

Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of

labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively; 0.20/0.08/0.16;

palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4

with lateral suface nearly straight, median surface rather markedly arcuate; palpomere 4 widest slightly past midlength.

Mentum wider than long, surface shining, finely and sparsely punctulate. Submentum microreticulate. Genae shining:

lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with fine, contiguous punctation.

Last five antennomeres pubescent. Eyes slightly less than 0.20 interocular distance in width. Thorax: Pronotum length at

midline 0.34 mm; maximum width (at anterior 0.33 mm) 0.44 mm; sides margined, denticulate; sides relatively weakly

produced at anterior 0.33, slightly arcuate and slightly convergent to anterior angle, sinuate and convergent to posterior;

anterior border 0.38 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in

middle 0.50; posterior border 0.42 mm wide, slightly arcuate to rear. Posterointernal foveolae absent. Posteroexternal

foveola absent. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly

less than 0.33 width of anterior region of pronotum. Transverse foveola absent. Disc shining, punctures fine, separated by

puncture diameter; most punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent.

Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina; carina

sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median

carina extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered; apex blunt, width at apex

0.50 distance between internal and median carinae. Metasternum with plaques well developed, triangular; plaques 0.33

length of metasternum in midline; width of each plaque subequal to width of intercoxal process at its apex; plaques

separated posteriorly by approximately plaque width; plaques flat in cross section. Elytra: Length 0.84 mm. Maximum

width (at midlength) 0.52 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows

quite regular; most punctures round; intervals not elevated, width approximately equal to 0.50 puncture diameter, as are

interstices between adjacent punctures of a row; each puncture with seta. Explanate margin quite narrow, ended near

posterior 0.20, with fine, well separated serrations in apical 0.33; serrations closer near apices. Elytral apices, in dorsal

aspect, gradually rounded; in posterior aspect, elytral margin elevated obliquely toward suture in form of angle with

opposite elytron. Abdomen: Intercoxal segment flat, longer than wide, posterior margin straight. Glabrous segments at

apex moderately produced. Segment 7 emarginate at apex. Legs: Protibia arcuate. Genitalia: Aedeagus as illustrated

(Fig. 5 1 B)( 1 examined).

Distribution. - (Fig. 170). Presently known only from Haiti.

Etymology. - Latin, haitensis , in reference to the known geographical distribution.

68. Hydraena mexicana new species

(Figs. 42A,51C,170)

Type-locality. - Four miles N. Bochil, Chiapas, Mexico.

Type-specimens. - The holotype male is deposited in USNM. My wife Maureen and I

collected this specimen, May 28, 1974. The allotype, collected by Hugh B. Leech, is deposited

Quaest. Ent., 1980, 16 (1,2)

172

Perkins

with the holotype and has the following data: Clear stream at Palitla, 5 mi. N. of

Tamazunchale, 22-XII-1948, San Lusi Potosi, Mexico. Paratypes (5) are listed in the

appendix.

Diagnosis. - The plaques are elongate, parallel, separated from one another by two-three

times the width of a plaque. The aedeagus must be studied to reliably discriminate males of

Hydraena mexicana from others in the marginicollis Subgroup with similar plaque

configuration.

Description. — Form: Elongate. Size: Holotype 1.42 mm long, 0.58 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum with subquadrate, dark brown

macula; lateral areas testaceous. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed

margin of pronotum brown. Head: Length 0.18 mm. Width 0.34 mm. Frons moderately punctured, interstices equal to or

slightly greater than puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus finely punctulate.

Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median

emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.24/0.14/0.16; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface very slightly arcuate, median surface

moderately arcuate; palpomere 4 widest near midlength. Mentum length equal width, surface markedly shining, punctures

fine and sparse. Submentum punctation similar to mentum. Genae moderately elevated, shining; lateral area of each gena

with well developed foveola; posterior ridge absent. Postgena with punctation much finer and closer than that of

submentum. Last five antennomeres pubescent. Eyes slightly greater than 0.25 interocular distance in width. Thorax:

Pronotum length at midline 0.36 mm; maximum width (at approximately midlength) 0.44 mm; sides margined,

denticulate; sides relatively slightly produced at middle, slightly arcuate and slightly convergent to anterior angle, slightly

sinuate and slightly convergent to posterior; anterior border 0.38 mm wide, straight and nearly perpendicular to midline in

lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.40 mm wide, slightly arcuate to rear.

Posterointernal foveolae absent. Posteroexternal foveola delimited by very shallow depression with punctation somewhat

closer than that of disc. Interfoveolar depression slightly developed. Area between external foveolae weakly elevated.

Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.33

width of anterior region of pronotum. Transverse foveola slightly developed, with punctures closer together than punctures

on disc. Disc shining, punctures fine, separated by one-two times puncture diameter; most punctures with distinctive seta

extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short

spine; coxae separated by thin, median carina, latter sinuate line in lateral aspect. Mesosternum with internal and external

carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process

moderately broad, sides tapered, apex blunt, width at apex slightly greater than 0.50 distance between internal and median

carinae. Metasternum with plaques moderately developed, straight, parallel; plaques 0.40 length of metasternum in

midline; width of each plaque subequal to width of intercoxal process at its apex; plaques separated posteriorly by

approximately twice plaque width; plaques on side of median depression, sloped very slightly toward midline. Elytra:

Length 0.86 mm. Maximum width (at midlength) 0.58 mm. Surface shining, disc with 10 rows of punctures between

suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal to

nearly twice puncture diameter, as are interstices between adjacent punctures of a row; punctures each with seta.

Explanate margin quite narrow, ended near posterior 0.12, with prominent serrations in posterior 0.33; serrations smaller

near apices. Elytral apices, in dorsal aspect, weakly truncate; in posterior aspect, elytral margin elevated obliquely toward

suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle, posterior

margin straight. Glabrous segments at apex moderately produced. Tergum 7 emarginate at apex; sternum with small,

circular excavation on inner surface. Legs: Protibia with inner surface straight, lateral surface slightly arucate. Metatibia

markedly enlarged in basal 0.17, gradually enlarged for remainder of length. Genitalia: Aedeagus as illustrated

(Fig. 51C)(5 examined).

Natural History. - Refer to H. splecoma .

Distribution. - (Figs. 42A,170). Presently known from the Mexican states of San Luis

Potosi, Veracruz and Chiapas.

Etymology. - Adjective, Latin form, mexicana , in reference to the geographical

distribution.

69. Hydraena perkinsi Spangler

(Figs. 51D,170)

Hydraena perkinsi Spangler, 1980:331 (holotype male in USNM; type-locality: Quenado de Pineda, Cuba).

Western Hemisphere Hydraenidae

173

Diagnosis. - Adults are moderately large, about 1 .48 mm long, with plaques subtriangular

in shape. The aedeagus must be used to differentiate Hydraena perkinsi males from those of

other members of the marginicollis Subgroup of similar body size and plaque configuration.

Figs. 51 A - D, Aedeagi of Hydraena holotypes. (A) H. guatemala. (B) H. haitensis. (C) H. mexieana. (D) H. perkinsi.

Quaest. Ent., 1980, 16 (1,2)

174

Perkins

Description. — Form: Elongate. Size: Holotype 1.48 mm long, 0.64 mm wide. Color: Head with dorsum black,

venter dark brown, palpi and antennae testaceous. Pronotum with anterior and posterior 0.25 testaceous, middle 0.50 with

black macula, macula lighter near sides. Elytra brown. Venter dark brown. Legs, inflexed margin of pronotum and elytral

epipleura testaceous. Head: Length 0.22 mm, width 0.36 mm. Frons moderately densely, moderately coarsely punctate,

most punctures separated by less than puncture diameter. Frontoclypeal suture slightly arcuate. Clypeus shiny, very finely

punctulate in middle, microreticulate laterally. Labroclypeal suture straight. Labrum microreticulate, bilobed, median

emargination ended near midlength. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4 respectively:

0.26/0.12/0.18; palpomere 4 asymmetrical, widest near distal 0.33. Mentum width equal length, punctulate,

microreticulate. Submentum microreticulate. Genae shiny, foveolate laterally. Postgena microreticulate. Thorax:

Pronotum length at midline 0.36 mm; maximum width (slightly before midlength) 0.48 mm; sides margined, finely

denticulate, very slightly produced, straight and slightly convergent to anterior angles, slightly sinuate and slightly

convergent to posterior angles; anterior border 0.40 mm wide, straight and nearly perpendicular to midline in lateral 0.20,

slightly arcuate in middle 0.60; posterior border very slightly arcuate to rear. Posterointernal and posteroexternal foveolae

absent. Anteroexternal foveolae well developed, each extended across 0.25 width of anterior region of pronotum. Disc

shiny, moderately densely, moderately coarsely punctate, most punctures separated by less than puncture diameter;

punctures without apparent seta. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine;

coxae separated by thin median carina, latter sinuate in lateral view. Mesosternum with internal and external carinae

divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively

narrow, apex blunt, width at apex 0.50 distance between internal and median carinae. Metasternum with plaques well

developed, flat, 0.50 length of metasternum, median margins parallel, lateral margins slightly convergent anteriorly; each

plaque tapered from posterior to anterior, width at base subequal width of intercoxal process; plaques separated at base by

twice plaque width. Elytra: Length 0.94 mm; Maximum width (at midlength) 0.64 mm. Disc shiny, with 10 rows of

moderately large punctures between suture and humeral callus; intervals not elevated, width subequal puncture diameter,

interstices between punctures of row slightly less. Explanate margin slightly developed, ended near posterior 0.20, border

finely serrate in posterior 0.33. Elytral apices slightly dehiscent in dorsal view; viewed posteriorly, elytral margin elevated

obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral

triangle; posterior margin straight. Glabrous segments at apex produced. Tergum 7 emarginate at apex. Legs: Protibia

slightly expanded and with two rows of short spines in distal 0.33. Other legs slender, unmodified. Genitalia: Aedeagus as

illustrated (Fig. 5 1 D)( 1 examined).

Variation. - Females lack the protibial modifications seen in males.

Distribution. - (Fig. 170). Cuba.

The jivaro Complex

70. Hydraena grouvellei d’Orchymont

(Figs. 52A.171B)

Hydraena grouvellei d’Orchymont, 1923:35 (holotype depository uncertain; type-locality: “Mexique (tabacs)”).

According to d’Orchymont (1923) the holotype is in the Paris Museum. Through the

courtesy of that institution I have been able to study a male paratype. There is a possibility that

further search will reveal the holotype, therefore I am not designating a lectotype at this time.

Diagnosis. - Distinguished from other members of the marginicollis Subgroup by the

extremely shiny dorsum and the arcuate, carinate plaques. The punctures on the pronotum are

very fine and widely spaced, interstices being three-six times puncture diameter. The elytra are

truncate in males (I have not seen females).

Description. — Form: Elongate-oval. Size: The paratype male 1 have studied is 1.43 mm long, 0.64 mm wide.

Color: Head with dorsal surface dark brown, black near eyes; labrum brown; maxillary palpi and antennae testaceous.

Pronotum dark brown except narrow testaceous anterior and posterior border. Elytra brown. Ventral surface dark brown

except legs, elytral epipleura and inflexed margin of pronotum, light brown. Head: Length 0.19 mm. Width 0.36 mm.

Frons finely and sparsely punctate, interstices two-four times puncture diameter; surface shining. Frontoclypeal suture

slightly arcuate to rear. Clypeus finely microreticulate at sides, impunctate and shining in midline. Labroclypeal suture

arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

Western Hemisphere Hydraenidae

175

0.28/0.12/0.20; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface straight, median surface arcuate; palpomere 4 widest at anterior 0.33.

Mentum wider than long, surface shining, finely punctulate. Submentum microreticulate. Genae shining; lateral area of

each gena with well developed foveola; posterior ridge absent. Postgena microreticulate. Last five

antennomeres pubescent. Eyes 0.20 interocular distance in width. Thorax: Pronotum length at midline 0.42 mm;

maximum width (at approximately midlength) 0.52 mm; sides margined, not denticulate in anterior 0.50, extremely

finely denticulate in posterior 0.50; sides relatively slightly produced at middle, very slightly arcuate and slightly

convergent to anterior angle, very slightly arcuate and slightly convergent to posterior; anterior border 0.44 mm wide,

straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border

O. 50 mm wide, slightly arcuate to rear. Posterointernal foveolae absent. Posteroexternal foveola absent. Anteroexternal

foveolae well developed, each foveola somewhat crescent shaped, extended across slightly less than 0.20 width of

anterior region of pronotum. Transverse foveola absent. Disc brilliantly shining, punctures extremely fine, separated by

three-six times puncture diameter; punctures without distinctive setae extended above cuticle in dry specimens. Scintilla

absent. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina;

carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to

posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered, apex

blunt, width at apex 0.50 distance separating internal and median carinae. Metasternum with plaques well developed,

carinate, markedly arcuate, 0.50 length of metasternum in midline; plaques separated posteriorly by approximately six

times plaque width. Elytra: Length 0.93 mm. Maximum width (at midlength) 0.64 mm. Surface shining, disc with 10

rows of punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated,

width approximately equal to twice puncture diameter, as are interstices between adjacent punctures of a row;

punctures without perceptible setae. Explanate margin moderately developed, ended near posterior 0.10, with extremely

fine, well separated serrations along anterior 0.66, quite large and distinct in posterior 0.33; serrations obsolete near

apices. Elytral apices, in dorsal aspect, truncate; in posterior aspect, elytral margin elevated obliquely toward suture, in

form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly an equilateral triangle, posterior margin

straight. Glabrous segments at apex well produced. Tergum 7 emarginate at apex; sternum with oval excavation on

inner surface in midline. Legs: Profemur with minute tubercle on inner surface near midlength. Protibia excavate on

inner surface near apex. Metatibia enlarged gradually from base to apex. Genitalia: Aedeagus as illustrated

(Fig. 52A)(2 examined).

Distribution. - (Fig. 17 IB). Exact location within Mexico uncertain. The single specimen I

have seen in addition to the paratype described above is also labelled “Mexique, tabacs”, which

is the only information given by d’Orchymont (1923) in the original description.

7 1 . Hydraena premordica new species

(Figs. 50B,52B,171B)

Type-locality. - Mayaro, Trinidad.

Type-specimens. - The holotype male is deposited in MCZ. This specimen was collected by

P. J. Darlington, April 28, 1929. The allotype, which is deposited in BMNH, has the following

data: British Guiana, Kanuku Mts., Rupununi, 61-2-21, T. Clay. Paratypes (24) have the same

data as the allotype and are deposited in BMNH, USNM and PDP.

Diagnosis. - Males are instantly recognized by the markedly truncate elytra; each elytron

has the posterior margin sinuate. Both sexes have a few punctures on the elytral disc random,

not in serial rows as are the remaining punctures. The elytra of females are slightly angulate on

the sides in the posterior, but the apices are not truncate. Plaques are well developed,

non-carinate.

Description. — Form: Elongate-oval. Size: Holotype 1.76 mm long, 0.76 mm wide. Color: Head with dorsal surface

brown, dark brown near eyes; labrum brown; antennae testaceous. Pronotum testaceous at anterior and posterior 0.20,

dark brown in middle 0.60. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed margin of

pronotum brown. Head: Length 0.20 mm. Width 0.42 mm. Frons moderately punctured, interstices generally less than

puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus finely punctulate. Labroclypeal suture straight

in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpi missing from specimen. Mentum wider than long, surface moderately

shining, microreticulate. Submentum microreticulate. Genae shining; lateral area of each gena with well developed

foveola; posterior ridge absent. Postgena with microreticulation similar to that of submentum. Last five

Quaest. Ent., 1980, 16 (1,2)

176

Perkins

antennomeres pubescent. Eyes slightly less than 0.20 interocular distance in width. Thorax: Pronotum length at midline

0.46 mm; maximum width (at approximately midlength) 0.58 mm; sides margined, denticulate; sides moderately

produced at middle, slightly arcuate and convergent to anterior angle, slightly sinuate and convergent to posterior;

anterior border 0.44 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear

in middle 0.50; posterior border 0.52 mm wide, slightly arcuate to rear. Posterointernal foveolae absent. Posteroexternal

foveola absent. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly

less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area closer

together than punctures on disc. Disc moderately shining, punctures fine, separated by thin walls near anterior and

posterior borders, by puncture diameter in middle; most punctures with distinctive seta extended above cuticle in dry

specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by

thin, median carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent

from anterior to posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow,

sides nearly parallel, apex blunt, width at apex 0.33 distance between internal and median carinae. Metasternum with

plaques well developed, straight, convergent moderately from posterior to anterior; plaques 0.50 length of metasternum

in midline; width of each plaque subequal to width of intercoxal process at its apex; plaques separated posteriorly by

approximately twice plaque width; plaques flat in cross section. Elytra: Length 1.04 mm. Maximum width (at

midlength) 0.76 mm. Surface shining, anterior 0.66 with random punctures gradually arranged into rows in posterior

0.33 of elytra; most punctures round; interstices generally less than puncture diameter; most punctures with seta.

Explanate margin quite narrow, ended at apices, with extremely fine, well separated serrations along entire margin.

Elytral apices, in dorsal aspect, truncate, apex of each elytron sinuate line; in posterior aspect, elytral margins together

in form of a half oval. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight. Glabrous segments

at apex moderately produced. Tergum 7 emarginate at apex; sternum with oval excavation on inner surface in midline.

Legs: Profemur with oblique carina on inner surface near basal 0.33. Protibia weakly arcuate; posterior surface with

prominent, tooth-like expansion at apical 0.33. Metafemur relatively narrow. Metatibia thin, parallel sided. Genitalia:

Aedeagus as illustrated (Fig. 52B)(2 examined).

Natural History. - Specimens from the Kanuku Mountains of Guyana have the label

notation: “debris edge of forest creek”.

Distribution. - (Figs. 50B,171B). Presently known from Trinidad and Guyana.

Etymology. - Latin, premordica (bitten off at the end). This name refers to the truncate

elytra of males.

72. Hydraena jivaro new species

(Figs. 50B,52C,171B)

Type-locality. - 3 kilometers S. Tena, Napo Province, Ecuador.

Type-specimens. - The holotype male, allotype and one female paratype are deposited in

USNM. These specimens were collected by P. J. Spangler and D. R. Givens, May 13, 1977.

Diagnosis. - Readily distinguished from Hydraena quechua adults, the only other

Hydraena now known from Ecuador, by larger size (1.48 vs 1.22 mm) and testaceous labrum.

The labrum of Hydraena quechua adults is black. Separation from other similarly sized and

sculptured members of the marginicollis Subgroup, however, must be based on the aedeagus.

Description. — Form: Elongate. Size: Holotype 1.48 mm long, 0.64 mm wide. Color: Dorsum with labrum

testaceous; clypeus brown in middle, testaceous laterally; frons black; pronotum with transverse black macula extended

from anterior 0.28 to posterior 0.14, remainder testaceous; elytra brown. Venter dark brown. Legs with basal 0.50 of femur

brown, remainder testaceous. Maxillae testaceous. Head: Length 0.22 mm; width 0.36 mm. Frons moderately punctate,

most punctures separated by puncture diameter, interstices shining. Frontoclypeal suture slightly arcuate. Clypeus shiny in

midline, microreticulate and dull laterally. Labroclypeal suture straight. Labrum bilobed, median emargination ended at

midlength, microreticulate. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4 respectively:

0.27/0.10/0.18; palpomere 4 asymmetrical, greatest width near apical 0.33. Mentum width equal length, shiny, finely

punctulate. Submentum microreticulate. Genae shiny, foveolate laterally; posterior ridge absent. Postgena microreticulate.

Thorax: Pronotum length at midline 0.40 mm; Maximum width (at midlength) 0.50 mm; sides margined, denticulate,

slightly produced at middle, slightly arcuate and slightly convergent to anterior angles, very slightly sinuate and slightly

convergent to posterior angles; anterior border 0.40 mm wide, straight and nearly perpendicular to midline in lateral 0.17,

moderately arcuate to rear in middle 0.66; posterior border 0.46 mm wide, very slightly arcuate to rear. Posterointernal

foveolae absent. Posteroexternal foveolae extremely shallow, nearly imperceptible. Interfoveolar depression shallow.

Anteroexternal foveolae well developed, each somewhat crescent shaped, extended about 0.25 width of anterior region of

Western Hemisphere Hydraenidae

Figs. 52 A - D, Aedeagi of Hydraena species. (A) H. grouvellei, paratype. (B) H. premordica , holotype. (C) H.

holotype. (D) H. anaphora , holotype.

Quaest. Ent., 1980, 16 (1,2)

178

Perkins

pronotum. Transverse foveola absent. Disc shiny, punctures slightly elongate, separated by thin walls near anterior and

posterior borders, by two-three times puncture width in middle; punctures without apparent setae. Scintilla absent.

Prosternum carinate; coxae separated by thin median carina, latter sinuate in lateral aspect. Mesosternum with internal

and external carinae divergent from anterior to posterior; median carina extended to base of intercoxal process;

intercoxal process relatively narrow, apex blunt, width at apex 0.50 distance between internal and median carinae.

Metasternum with well developed parallel plaques, separated by twice plaque width, 0.50 length of metasternum; each

plaque about as wide as apex of intercoxal process. Elytra: Length 0.96 mm; maximum width (at midlength) 0.64 mm.

. Disc shiny, with 10 rows of moderate sized punctures between suture and humeral callus; intervals not elevated, width

slightly less than puncture width, as are interstices between punctures of a row; punctures with very fine seta. Explanate

margin moderately developed, ended near posterior 0.20. Elytral border from posterior 0.20 to apices finely serrate.

Elytral apices nearly truncate in dorsal view; viewed posteriorly, elytral margin elevated obliquely toward suture, in

form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly equilateral triangle, posterior margin

straight. Glabrous segments at apex produced. Tergum 7 emarginate at apex. Legs: Profemur with small carina on inner

surface near basal 0.33. Protibia excavate on inner surface from basal 0.25 to apex, small tooth at base of excavation.

Other legs apparently unmodified. Genitalia: Aedeagus as illustrated (Figure 52C) (1 examined).

Distribution. - (Figs. 50B,171B). Known only from the typelocality near Tena in Napo

Province of Ecuador.

Etymology. - Noun in apposition, Latin in form, jivaro, in reference to the Jivaro Indians of

Ecuador.

73. Hydraena anaphora new species

(Figs. 52D.171B)

Type-locality. - Cuyaba, Matto Grosso, Brazil.

Type-specimen. - The holotype male (unique) is deposited in CMP. The collector and date

are unknown.

Diagnosis. - The arcuate plaques which are elevated in the anterior, plus non-modified

metatibiae of males serve to distinguish H. anaphora adults from other members of the

marginicollis Subgroup. Plaques are widest at their bases, about as wide as the mesosternal

process; three times this distance separates the plaques at their bases. Each plaque narrows

anteriorly to form an elevated, subcariniform prominence.

Description. — Form: Elongate. Size: Holotype 1 .60 mm long, 0.64 mm wide. Color: Head with dorsal surface dark

brown, nearly black adjacent to eyes; labrum testaceous; maxillary palpi brown; antennae testaceous. Pronotum testaceous

at anterior and posterior 0.20, dark brown in middle 0.60; sides slightly lighter than disc. Elytra brown. Ventral surface

dark brown except legs, elytral epipleura and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width

0.36 mm. Frons moderately punctured, interstices equal to or slightly greater than puncture diameter; surface shining.

Frontoclypeal suture straight. Clypeus finely punctulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed,

microreticulate, each lobe symmetrical arc; median emargination ended slightly above midlength of labrum. Maxillary

palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.26/ 0.12/0.20; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly

straight in basal 0.33, arcuate in apical 0.66, median surface more markedly arcuate; tarsomere 4 widest slightly past

midlength. Mentum wider than long, surface moderately shining, finely and sparsely punctulate. Submentum

microreticulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with

microreticulation slightly larger than that of submentum. Last five antennomeres pubescent. Eyes slightly greater than

0.25 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm; maximum width (at approximately

midlength) 0.48 mm; sides margined, denticulate; sides moderately produced at middle, slightly arcuate and slightly

convergent to anterior angle, sinuate and convergent to posterior; anterior border 0.40 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.44 mm. wide,

slightly arcuate to rear. Posterointernal foveolae absent. Interfoveolar depression moderately developed. Posteroexternal

foveolae absent. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended across slightly

less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area somewhat

closer together than punctures on disc. Disc shining, punctures fine, separated by one-three times puncture diameter; most

punctures without distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina

produced anteriorly as very short spine; coxae separated by thin, median carina; carina sinuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to base of

intercoxal process; intercoxal process relatively narrow, sides nearly parallel in apical 0.50, apex blunt, width at apex 0.33

Western Hemisphere Hydraenidae

179

distance between internal and median carinae. Metasternum with plaques well developed, slightly arcuate, convergent

from posterior to anterior; plaques 0.50 length of metasternum in midline; greatest width of each plaque subequal to

width of intercoxal process at its apex; plaques separated posteriorly by approximately three times plaque width; each

plaque narrowed to thin elevated, subcariniform prominence at anterior. Elytra: Length 0.96 mm. Maximum width (at

midlength) 0.64 mm. surface shining, disc with 10 rows of punctures between suture and humeral callus, rows

somewhat irregular; most punctures round; intervals not elevated, width approximately equal to puncture diameter, as

are interstices between adjacent punctures of row; each puncture with seta. Explanate margin quite narrow, ended near

posterior 0.20, with extremely fine, well separated serrations along entire margin; serrations somewhat closer near

apices. Elytral apices, in dorsal aspect, truncate; in posterior aspect, elytral margin elevated obliquely toward suture, in

form of angle with opposite elytron. Abdomen: Intercoxal segment flat, wider than long, posterior margin straight.

Glabrous segments at apex moderately produced. Tergum 7 emarginate at apex; sternum with a round excavation on

inner surface in midline. Legs: Profemur with oblique, cariniform protuberance on inner surface near basal 0.33.

Protibia very slightly arcuate; inner surface expanded in apical 0.33. Metafemur broad; anterior surface markedly

arcuate; posterior sinuate. Metatibia slender, nearly parallel sided in apical 0.66. Genitalia: Aedeagus as illustrated

(Fig. 52D) (1 examined).

Distribution. - (Fig. 17 IB). Presently known only from the type-locality in Matto Grosso,

Brazil.

Etymology. - Latin, anaphora (a rising). Named in reference to the raised anterior region

of the plaques.

74. Hydraena hyalina new species

(Figs. 64A,92A,171B)

Type-locality. - 32 km. SW Calabozo, Guarico, Venezuela.

Type-specimens. - The holotype male is deposited in USNM. The allotype, also deposited in

USNM, has the following data: 15 km. S. Calabozo, Guarico, Venezuela. These specimens

were collected by Paul and Phyllis Spangler, February 9-11, 1969. Paratypes (70) are listed in

the appendix.

Diagnosis. - This species cannot be adequately characterized on the basis of external

features at this time. The aedeagus must be studied to reliably distinguish males of Hydraena

hyalina from others in the marginicollis Subgroup. The pronotum is relatively coarsely

punctate and has very shallow posterointernal foveolae, which would indicate that this species

should be placed in the lee chi Group. The aedeagus, however, appears to be most similar to

males of the marginicollis Group, hence its placement here.

Description. — Form: Elongate. Size: Holotype 1.44 mm long, 0.56 mm wide. Color: Head with dorsum and

labrum black; maxillary palpi and antennae testaceous. Pronotum testaceous at anterior and posterior 0.25, black in

middle 0.50; black of disc blending into brown at sides. Elytra brown. Ventral surface dark brown except legs, elytral

epipleura and inflexed margin of pronotum brown. Head: Length 0.20 mm. Width 0.36 mm. Frons moderately punctured,

interstices equal to or slightly less than puncture diameter; surface shining. Frontoclypeal suture, straight. Clypeus finely

punctulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical arc;

median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively: 0.20/0.08/0.16; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface weakly arcuate, median surface more

markedly arcuate; palpomere 4 widest slightly past midlength. Mentum wider than long, surface shining, moderately and

sparsely punctulate. Submentum microreticulate. Genae shining; lateral area of each gena with well developed foveola;

posterior ridge absent. Postgena with microreticulation similar to that of submentum. Last five antennomeres pubescent.

Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at midline 0.32 mm; maximum width

(at approximately midlength) 0.46 mm; sides margined, denticulate; sides relatively slightly produced at middle, slightly

arcuate and slightly convergent to anterior angle, very slightly sinuate and slightly convergent to posterior; anterior border

0.40 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50;

posterior border 0.44 mm wide, slightly arcuate to rear. Posterointernal foveolae very shallow. Posteroexternal foveola

absent. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended slightly less than 0.33

width of anterior region of pronotum. Transverse foveola slightly developed, punctures separated by thin walls. Disc

moderately shining, punctures fine, close and rather deeply impressed, separated by 0.50 puncture diameter near anterior

and posterior borders, by puncture diameter in middle; most punctures with seta extended above cuticle in dry specimens.

Quaest. Ent., 1980, 16 (1,2)

180

Perkins

Scintilla absent. Prosternum carinate, carina produced anteriorly as very short spine; coxae separated by thin, median

carina; carina sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to

posterior; median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides tapered; apex

rounded, width near apex 0.33 distance between internal and median carinae. Metasternum with plaques moderately

developed, straight, convergent very slightly from posterior to anterior; plaques 0.43 length of metasternum in midline;

width of each plaque subequal to width of intercoxal process at its midlength; plaques separated posteriorly by

approximately twice plaque width; plaques flat in cross section. Elytra: Length 0.88 mm. Maximum width (at

midlength) 0.56 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width approximately equal to 0.50 puncture diameter, as are

interstices between adjacent punctures of a row; each puncture with seta. Explanate margin quite narrow, ending near

posterior 0.20, with extremely fine, well separated serrations along entire margin; serrations somewhat closer near

apices. Elytral apices, in dorsal aspect, almost truncate; viewed posteriorly, elytral margin elevated obliquely toward

suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly equilateral triangle, posterior

margin straight. Glabrous segments at apex well produced. Tergum 7 emarginate at apex; sternum with round

excavation on inner surface in midline. Legs: Protibiae rather markedly arcuate. Metatibia gradually enlarged to apex.

Genitalia: Aedeagus as illustrated (Fig. 64A)(37 examined).

Distribution. - (Figs. 92A,171B). Presently known from southeastern Brazil, Guyana, and

Venezuela.

Etymology. - Latin, hyalina (glassy, transparent). This name refers to the major process of

the aedeagus.

The trinidensis Complex

75. Hydraena browni new species

(Figs. 53A-B,92A,172A)

Type-locality. - San Fernando, Guarico, Venezuela.

Type-specimens. - The holotype male and allotype with identical locality data are deposited

in USNM. One male and one female paratype, same data as holotype, are also deposited in

USNM. Paul and Phyllis Spangler collected these specimens, February 12, 1969. One male

and two female paratypes (PDP) are from Para, Brazil.

Diagnosis. - The aedeagus must be used to reliably differentiate H. browni males from

other members of the marginicollis Subgroup of similar size, about 1.16 mm, and with plaques

elongate, separated by three times plaque width.

Description. — Form: Elongate. Size: Holotype 1.16 mm long, 0.50 mm wide. Color: Head with dorsal surface

black, with vague purple reflections; labrum black; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous

at anterior and posterior 0.25, black in middle 0.50; black blending into brown at sides. Elytra brown. Ventral surface dark

brown except legs, elytra epipleura and inflexed margin of pronotum brown. Head: Length 0.18 mm. Width 0.32 mm.

Frons finely and sparsely punctured, interstices twice puncture diameter; surface shining. Frontoclypeal suture straight.

Clypeus finely punctulate. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe

symmetrical arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following

lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.20/0.08/0.16; palpomere 2 bent outward at approximately

midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface slightly arcuate, median

surface more markedly arcuate. Mentum wider than long, surface shining, finely and sparsely punctulate. Submentum

sparsely, finely punctulate. Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent.

Postgena with punctation slightly smaller than that of submentum. Last five antennomeres pubescent. Eyes slightly less

than 0.25 interocular distance in width. Thorax: Pronotum length at midline 0.30 mm; maximum width (at approximately

midlength) 0.42 mm; sides margined, denticulate; sides relatively slightly produced at middle, slightly arcuate and slightly

convergent to anterior angle, very slightly sinuate and slightly convergent to posterior; anterior border 0.36 mm wide,

straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border

0.38 mm wide, slightly arcuate to rear. Posterointernal foveolae absent. Posteroexternal foveola absent. Anteroexternal

foveolae well developed, each foveola somewhat cresent shaped, extended slightly less than 0.33 width of anterior region of

Western Hemisphere Hydraenidae

181

Figs. 53A - D, Aedeagi of Hydraena species. (A) H. browni, holotype. (B) H. browni variant from Para, Brazil. (C) H.

trinidensis, holotype. (D) H. insular is, holotype.

Quaest. Ent., 1980, 16 (1,2)

182

Perkins

pronotum. Transverse foveola absent. Disc shining, punctures fine, separated by one-three times puncture diameter;

most punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate,

carina produced anteriorly as very short spine; coxae separated by thin, median carina, latter sinuate line in lateral

aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to

base of intercoxal process; intercoxal process relatively narrow, sides tapered, apex blunt, width at apex 0.50 distance

between internal and median carinae. Metasternum with plaques moderately developed, straight, convergent moderately

from posterior to anterior; plaques 0.57 length of metasternum in midline; width of each plaque subequal to width of

intercoxal process at its apex; plaques separated posteriorly by approximately three times plaque width; plaques flat in

cross section. Elytra: Length 0.76 mm. Maximum width (at midlength) 0.50 mm. surface shining, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width

approximately equal to 0.50 puncture diameter, as are interstices between adjacent punctures of a row; each puncture

with a seta. Explanate margin quite narrow, ending near posterior 0.20, with extremely fine serrations in posterior 0.33.

Elytral apices, viewed from above, truncate; in posterior aspect, elytral margin rises obliquely toward suture, in form of

angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly equilateral triangle, posterior margin straight.

Glabrous segments at apex moderately produced, directed ventrad. Tergum 7 emarginate at apex; sternum with oval

excavation on inner surface at apex. Legs: Protibia excavate on inner surface at apex. Metafemur gradually enlarged

from base to apex. Genitalia: Aedeagus as illustrated (Figs. 53A-B)(16 examined).

Variation. - I have illustrated the aedeagus of a male from Para, Brazil (Fig. 53B), which

differs slightly from specimens from Venezuela. Externally, specimens from the two areas

compare very well.

Distribution. - (Figs. 92A,172A). Presently known from San Fernando, Venezuela, which is

in the Orinoco drainage system, and Para (Belem), Brazil, at the mouth of the Amazon River.

Etymology. - I am pleased to dedicate this species to Harley P. Brown in recognition of his

contributions to this study and to the study of aquatic Coleoptera in general.

76. Hydraena trinidensis new species

(Figs. 53C,172A)

Type-locality. - St. Augustine, Trinidad.

Type-specimens. - The holotype male is deposited in MCZ. The allotype and four female

paratypes from Mayaro, Trinidad, are also deposited in MCZ. These specimens were collected

by P. J. Darlington, April, 1929.

Diagnosis. - Difficult to differentiate from other members of the marginicollis Subgroup

which are about the same size (1.34 mm) and have the plaques moderately developed. The

aedeagus (Fig. 53C) must be studied to reliably assign males to this species.

Description. — Form: Elongate. Size: Holotype 1.34 mm long, 0.56 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and posterior

0.25, dark brown in middle 0.50; sides slightly lighter than middle. Elytra brown. Ventral surface dark brown except legs,

elytral epipleura and inflexed margin of pronotum testaceous. Head: Length 0.18 mm; width 0.34 mm. Frons moderately

punctured, interstices one-two times puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus finely

microreticulate at sides, shining in midline. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate,

each lobe symmetrical arc; median emargination ending at approximately midlength of labrum. Maxillary palpus with

following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.24/0.08/0.16; palpomere 2 bent outward at

approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface slightly

arcuate, median surface rather markedly arcuate; palpomere 4 widest slightly past midlength. Mentum wider than long,

surface shining, finely and sparsely punctulate. Submentum finely punctulate, many punctures contiguous. Genae shining;

lateral area of each gena with well developed foveola; posterior ridge absent. Postgena microreticulate. Last five

antennomeres pubescent. Eyes slightly less than 0.25 interocular distance in width. Thorax: Pronotum length at midline

0.36 mm; maximum width (at approximately midlength) 0.44 mm; sides margined, denticulate; sides relatively slightly

produced at middle, slightly arcuate and slightly convergent to anterior angle, very slightly sinuate and slightly convergent

to posterior; anterior border 0.38 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately

arcuate to rear in middle 0.50; posterior border 0.40 mm wide, slightly arcuate to rear. Posterointernal foveolae absent.

Posteroexternal foveola absent. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended

slightly less than 0.33 width of anterior region of pronotum. Transverse foveola not developed, punctures in this area

somewhat closer together than punctures on disc. Disc shining, punctures fine, separated by one-three times puncture

Western Hemisphere Hydraenidae

183

diameter; most punctures with distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum

carinate, carina produced anteriorly as very short spine; coxae separated by thin, median carina, latter sinuate line in

lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior; median carina

extended to base of intercoxal process; intercoxal process relatively narrow, sides nearly parallel; apex blunt, width at

apex 0.50 distance between internal and median carinae. Metasternum with plaques moderately developed, triangular,

convergent moderately from posterior to anterior; plaques 0.43 length of metasternum in midline; greatest width of each

plaque subequal to width of intercoxal process at its apex; plaques separated posteriorly by approximately twice plaque

width; plaques on sides of median depression, sloped slightly toward midline. Elytra: Length 0.84 mm. Maximum width

(at midlength) 0.56 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

regular; most punctures round; intervals not elevated, width approximately equal to puncture diameter, as are interstices

between adjacent punctures of a row; most punctures with a seta. Explanate margin quite narrow, ended near posterior

0.20, with extremely fine, well separated serrations in apical 0.33. Elytral apices, in dorsal aspect, almost truncate; in

posterior aspect, elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen:

Intercoxal segment flat, longer than wide, posterior margin straight. Glabrous segments at apex moderately produced.

Tergum 7 emarginate at apex; sternum with oval excavation on inner surface in midline. Legs: Protibia slightly arcuate,

excavate on inner surface near apex. Genitalia: Aedeagus as illustrated (Fig. 53C)(1 examined).

Distribution. - (Fig. 172A). Presently known only from the island of Trinidad.

Etymology. - Latin adjective, trinidensis, in reference to the geographical distribution.

77. Hydraena insularis d’Orchymont

(Figs. 53D,172A)

Hydraena insularis d’Orchymont, 1945a:2 (holotype depository uncertain; type-locality: Guadeloupe).

Through the courtesy of the Institut Royal des Sciences Naturelles de Belgique, Brussels, I

have studied a male paratype of H. insularis. I am of the opinion that additional search may

reveal the holotype; therefore a lectotype is not designated herein.

Diagnosis. - Plaques of adults are well developed, triangular, separated at their bases by

about twice the greatest width of a plaque. Positive identifications of males must be based upon

the aedeagal form (Fig. 53D).

Description. — Form: Elongate. Size: Paratype 1.54 mm long, 0.68 mm wide. Color: Head with dorsal surface dark

brown; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior and posterior

0.25, dark brown in middle 0.50. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed

margin of pronotum brown. Head: Length 0.22 mm. Width 0.38 mm. Frons finely and sparsely punctured, interstices

one-three times puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus finely microreticulate at sides,

shining in midline. Labroclypeal suture arcuate in dorsal aspect. Labrum bilobed, microreticulate, each lobe symmetrical

arc; median emargination ended at approximately midlength of labrum. Maxillary palpus with following lengths (mm) of

palpomeres 2, 3 and 4, respectively; 0.28/0.12/0.18; palpomere 2 bent outward at approximately midlength; apices of

palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral surface nearly straight, median surface arcuate,

widest slightly past midlength. Mentum wider than long, surface moderately shining, punctures fine, separated by

puncture diameter. Submentum microreticulate. Genae shining; lateral area of each gena with well developed foveola;

posterior ridge absent. Postgena with punctation slightly larger than that of submentum. Last five

antennomeres pubescent. Eyes 0.25 interocular distance in width. Thorax: Pronotum length at midline 0.40 mm;

maximum width (at approximately midlength) 0.50 mm; sides margined, denticulate; sides relatively slightly produced at

middle, slightly arcuate and slightly convergent to anterior angle, slightly sinuate and slightly convergent to posterior;

anterior border 0.42 mm wide, straight and nearly perpendicular to midline in lateral 0.25, moderately arcuate to rear in

middle 0.50; posterior border 0.46 mm wide, slightly arcuate to rear. Posterointernal and posteroexternal foveolae absent.

Transverse foveola not developed, punctures in this area closer together than punctures on disc. Disc shining, punctures

fine, separated by puncture diameter near anterior and posterior borders, and by two-three times puncture diameter in

middle; punctures without distinctive setae extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate,

carina produced anteriorly as short spine; coxae separated by thin, median carina, latter sinuate line in lateral aspect.

Mesosternum with internal and external carinae divergent from anterior to posterior; median carina extended to base of

intercoxal process; intercoxal process relatively broad, sides nearly parallel, apex blunt, width at apex nearly 0.66 distance

separating internal and median carinae. Metasternum with plaques well developed, triangular, straight; plaques 0.50

length of metasternum in midline; greatest width of each plaque slightly greater than width of intercoxal process at its

midlength; plaques separated posteriorly by approximately twice plaque width; each plaque tapered from posterior to

anterior; plaques on sides of median depression, sloped slightly toward midline. Elytra: Length 1 .00 mm. Maximum width

(at midlength) 0.68 mm. Surface shining, disc with 10 rows of punctures between suture and humeral callus, rows quite

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Perkins

regular; most punctures round; intervals not elevated, width slightly greater than puncture diameter, as are interstices

between adjacent punctures of row; punctures without perceptible setae. Explanate margin quite narrow, ended near

posterior 0.20, with extremely fine, well separated serrations along entire margin; serrations somewhat closer near

apices. Elytral apices, in dorsal aspect, nearly truncate; in posterior aspect, elytral margin extended obliquely toward

suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment flat, nearly equilateral triangle, posterior

margin straight. Glabrous segments at apex moderately produced. Tergum 7 emarginate at apex; sternum with oval

excavation on inner surface to left of midline. Legs: Protibiae with a very small excavation on inner surface at apex.

Metatibiae gradually enlarging from base to apex. Genitalia: Aedeagus as illustrated (Fig. 53D)(2 examined).

Distribution. - (Fig. 172A). Presently known from Guadeloupe and Dominica (1 specimen

from the latter; see appendix).

Remarks. - The aedeagus I have illustrated from a paratype agrees well with the partial

illustration presented by d’Orchymont (1945). The aedeagus appears flattened because it had

been mounted on a microslide by a previous worker.

The marginicollis Complex

78. Hydraena marginicollis Kiesen wetter

(Figs. 54A-I,55A,56A,172B)

Hydraena marginicollis Kiesenwetter, 1849:177 (neotype deposited in USNM, herein designated; type-locality: three

miles S. Sopchoppy, Wakulla County, Florida). - d’Orchymont, 1923:36. - d’Orchymont 1945:1 Young, 1954:204.

Attempts to determine the location of the holotype of H. marginicollis have been

unsuccessful. I believe that this specimen has been destroyed. To insure taxonomic stability a

neotype is designated herein.

Diagnosis. - H. marginicollis is the only member of the marginicollis Group now known

from eastern North America (Fig. 56 A). H. marginicollis adults are distinguished from most

members of the marginicollis Subgroup by the moderate body size, about 1 .48 mm long, and

absence of metasternal plaques; the aedeagus must be used to differentiate males of this species

from others, such as H. pulsatrix, which also lack plaques.

Description. — Form: Elongate. Size: Neotype 1.48 mm long, 0.60 mm wide. Color: Head with dorsal surface dark

brown, nearly black; labrum dark brown; maxillary palpi testaceous; antennae testaceous. Pronotum testaceous at anterior

and posterior 0.19, dark brown in middle 0.66; testaceous areas slightly larger at anterior and posterior angles; macula

slightly lighter at sides of pronotum. Elytra brown. Ventral surface dark brown except legs, elytral epipleura and inflexed

margin of pronotum testaceous. Head: Length 0.20 mm. Width 0.32 mm. Frons finely and sparsely punctured, interstices

one-two times puncture diameter; surface shining. Frontoclypeal suture straight. Clypeus finely punctulate. Labroclypeal

suture arcuate when viewed from above. Labrum bilobed, each lobe symmetrical arc; median emargination ended at

approximately midlength of labrum. Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively:

0.24/0.12/0.16; palpomere 2 bent outward at approximately midlength; apices of palpomeres 2 and 3 not especially

expanded; palpomere 4 with lateral surface straight, median surface arcuate; palpomere 4 widest near midlength. Mentum

width equal length, surface shining, finely and sparsely punctulate. Submentum finely punctulate, surface somewhat

irregular. Genae shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with

punctation much closer than those of mentum, contiguous. Last five antennomeres pubescent. Eyes 0.25 interocular

distance in width. Thorax: Pronotum length at midline 0.36 mm. maximum width (at approximately midlength) 0.46 mm;

sides margined, denticulate; sides relatively slightly produced at middle, slightly arcuate and slightly convergent to

anterior angle, very slightly sinuate and slightly convergent to posterior; anterior border 0.40 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.42 mm wide, slightly

arcuate to rear. Posterointernal foveolae absent. Posteroexternal foveola absent. Anteroexternal foveolae well developed,

each foveola somewhat crescent shaped, extended slightly less than 0.25 width of anterior region of pronotum. Transverse

foveola absent. Disc shining, punctures fine, separated by puncture diameter near anterior and posterior borders, and by

twice puncture diameter in middle; punctures without distinctive setae extended above cuticle in dry specimens. Scintilla

absent. Prosternum carinate, carina produced anteriorly into very short spine; coxae separated by thin, median carina,

latter sinuate line in lateral aspect. Mesosternum with internal and external carinae divergent from anterior to posterior;

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Figs. 54A - I, Hydraena marginicollis, <3. (A) dorsal habitus. (B) ventral habitus. (C) pronotum. (D) head, ventral aspect.

(E) elytra, posterior aspect. (F) metatibia. (G) prothoracic leg. (H) apex of protibia. (I) prosternum with leg removed.

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Perkins

median carina extended to base of intercoxal process; intercoxal process relatively narrow, sides nearly parallel, apex

blunt, width at apex 0.50 distance between internal and median carinae. Metasternum with plaques absent. Elytra:

Length 0.89 mm. Maximum width (at midlength) 0.60 mm. Surface shining, disc with 10 rows of punctures between

suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width approximately equal

to puncture diameter, as are interstices between adjacent punctures of a row; most punctures with perceptible seta.

Explanate margin quite narrow, ended near posterior 0.20, with extremely fine, well separated serrations along entire

margin; serrations somewhat closer near apices. Elytral apices, in dorsal aspect, almost truncate; in posterior aspect,

elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment

flat, nearly equilateral triangle; anterior angle rounded; posterior margin straight. Glabrous segments at apex greatly

produced. Tergum 7 emarginate at apex; sternum with oval excavation on inner surface to left of midline. Legs:

Profemur with small tubercle on inner surface near midlength. Protibia excavate on inner surface near apex. Metatibia

nearly parallel sided in apical 0.66. Genitalia: Aedeagus as illustrated (Fig. 55A)(60 examined).

Natural History. - H. marginicollis is primarily a lowland pond species (Fig. 194C). It is

quite common in Florida, being collected in such areas as, “emergent vegetation at lake shore”,

“small pools adjacent to reservoir”, “litter under water hyacinth at creek”, and “debris, lake

shore”. There is also some indication that it may be slightly salt tolerant. I have examined 177

specimens (see appendix).

Distribution. - (Figs. 56A,172B). Eastern North America, primarily coastal, from New

Jersey south to Louisiana.

79. Hydraena turrialba new species

(Figs. 55B,172B)

Type-locality. - Turrialba, Costa Rica.

Type-specimens. - The holotype male, allotype and one female paratype with same locality

data are deposited in USNM. Paul J. Spangler collected these specimens, July 15, 1965.

Diagnosis. - Aedeagal form is the only reliable means of distinguishing males of H.

turrialba from those of other species of the marginicollis Subgroup which have small, oval

plaques and are of approximately the same body size (1.40 x 0.64 mm).

Description. — Form: Elongate. Size: Holotype 1.40 mm long, 0.64 mm wide. Color: Head with dorsal surface

black except for brown area near eyes; labrum dark brown; maxillary palpi and antennae testaceous. Pronotum testaceous

at anterior and posterior 0.25, black in middle 0.50; black blending into dark brown at sides. Elytra brown. Ventral surface

dark brown except legs, elytral epipleura and indexed margin of pronotum brown. Head: Length 0.20 mm. Width

0.36 mm. Frons finely punctured, interstices one-three times puncture diameter; surface shining. Frontoclypeal suture

straight. Clypeus finely microreticulate at sides, shining in middle. Labroclypeal suture arcuate in dorsal aspect. Labrum

bilobed, microreticulate, each lobe symmetrical arc; median emargination ended at approximately midlength of labrum.

Maxillary palpus with following lengths (mm) of palpomeres 2, 3 and 4, respectively: 0.24/0.10/0.16; palpomere 2 bent

outward at approximately midlength; apices of palpomeres 2 and 3 not especially expanded; palpomere 4 with lateral

surface slightly arcuate, median surface more markedly arcuate; palpomere 4 widest slightly past midlength. Mentum

wider than long, surface shining, finely and sparsely punctulate. Submentum finely and sparsely punctulate. Genae

moderately shining; lateral area of each gena with well developed foveola; posterior ridge absent. Postgena with punctation

slightly smaller than that of submentum. Last five antennomeres pubescent. Eyes slightly less than 0.25 interocular

distance in width. Thorax: Pronotum length at midline 0.38 mm; maximum width (at approximately midlength) 0.48 mm;

sides margined, denticulate; sides relatively weakly produced at middle, slightly arcuate and slightly convergent to anterior

angle, very slightly sinuate and slightly convergent to posterior; anterior border 0.40 mm wide, straight and nearly

perpendicular to midline in lateral 0.25, moderately arcuate to rear in middle 0.50; posterior border 0.44 mm wide, slightly

arcuate to rear. Posterointernal foveolae absent; punctures in foveola similar to those on disc. Posteroexternal foveola

absent. Anteroexternal foveolae well developed, each foveola somewhat crescent shaped, extended slightly less than 0.33

width of anterior region of pronotum. Transverse foveola absent. Disc shining, punctures fine, separated by puncture

diameter near anterior and posterior borders, and by two-three times puncture diameter in middle; most punctures with

distinctive seta extended above cuticle in dry specimens. Scintilla absent. Prosternum carinate, carina produced anteriorly

as very short spine; coxae separated by thin, median carina, latter sinuate line in lateral aspect. Mesosternum with internal

and external carinae divergent from anterior to posterior; median carina extended to base of intercoxal process; intercoxal

process relatively narrow, sides tapered, apex blunt, width at apex 0.33 distance between internal and median carinae.

Metasternum with plaques very slightly developed, small ovals at posterior 0.20; width of each plaque 0.50 width of

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intercoxal process at its apex; plaques separated posteriorly by approximately four times plaque width; plaques flat in

cross section. Elytra: Length 0.92 mm. Maximum width (at midlength) 0.64 mm. Surface shining, disc with 10 rows of

punctures between suture and humeral callus, rows quite regular; most punctures round; intervals not elevated, width

approximately equal to puncture diameter, as are interstices between adjacent punctures of row; each puncture with

seta. Explanate margin quite narrow, ended near posterior 0.20, with fine serrations near anterior angles and in

posterior 0.33; serrations somewhat closer near apices. Elytral apices, in dorsal aspect, truncate; in posterior aspect,

elytral margin elevated obliquely toward suture, in form of angle with opposite elytron. Abdomen: Intercoxal segment

flat, wider than long, posterior margin straight. Glabrous segments at apex clearly produced, arched ventrad. Tergum 7

emarginate at apex; sternum with small, oval excavation on inner surface distinctly to left of midline. Legs: Profemur

with tubercle on inner surface near midlength. Protibia slightly arcuate, excavate at apex. Metatibia nearly