The Pan-Pacific Entomologist

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PAN-PACIFIC ENTOMOLOGIST

70(1): 1-102, (1994)

A REVISION OF THE APHID GENUS ESSIGELLA

(HOMOPTERA: APHIDIDAE: LACHNINAE):

ITS ECOLOGICAL ASSOCIATIONS WITH, AND

EVOLUTION ON, PINACEAE HOSTS

John T. Sorensen

Insect Taxonomy Laboratory,

California Department of Food & Agriculture,

Sacramento, California 95814

Abstract.— This revision recognizes 13 species, 2 subspecies, and 3 subgenera of Essigella aphids

of the lachnine subtribe Eulachnina. Essigella (Archeoessigella) NEW SUBGENUS, Essigella

(Lambersella) NEW SUBGENUS, E. (L.) eastopi NEW SPECIES, E. (L.) hillerislambersi NEW

SPECIES, E. (E.) critchfieldi NEW SPECIES, and E. (L.)fusca voegtlini NEW SUBSPECIES are

described. The taxonomic status is changed for E. ( E .) knowltoni braggi Hottes NEW STATUS,

E. agilis Hottes NEW SYNONYM, E. claremontiana Hottes NEW SYNONYM, E. cocheta

Hottes NEW SYNONYM, E. gillettei Hottes NEW SYNONYM, E. maculata Hottes NEW

SYNONYM, E. monelli Hottes NEW SYNONYM, E. oregonensis Hottes NEW SYNONYM,

E. palmerae Hottes NEW SYNONYM, E. patchae Hottes NEW SYNONYM, E. pergandi Hottes

NEW SYNONYM, E. pineti Hottes NEW SYNONYM, E. robusta Hottes NEW SYNONYM,

and E. swaini Hottes NEW SYNONYM. A phylogenetic tree for the genus is reviewed; that

estimate, which used Pseudessigella as a outgroup and employs evolutionary quantitative genetic

rationales, was produced using discriminant function analysis and a maximum-likelihood net¬

working algorithm, because conventional cladistic characters were inadequate within the genus.

The phylogeny is corroborated because it closely reflects the genetic relationships of the aphid’s

Pinaceae hosts, and their biogeographic origins. Essigella appear to have evolved with their

hosts, or in a resource-tracking fashion, and seem to display instances of character-displacement

among closely related species in (or near) sympatry, presumably as a result of competition of

their host pines as resources.

Key Words. — Insecta, phylogeny, host associations, character displacement, evolutionary quan¬

titative genetics

This study addresses the systematics, phylogeny and host associations of Es¬

sigella. The genus, one of three composing the subtribe Eulachnina (Lachninae:

Cinarini), is restricted to North America and is the only native Nearctic group of

the subtribe. Essigella are linear-bodied and feed on the needles of Pinaceae,

chiefly Pinus but also Pseudotsuga and Picea. They are solitary aphids that move

quite rapidly when disturbed; several may group facultatively near the base of a

needle, where they may be tended by ants. Cage studies of individual aphids

(unpublished data) on marked needles indicated that adult virginoparous apterae

of Essigella readily wander over pine branches.

Essigella is often most abundant early in the season (Burke 1937), and may

damage pines (Turpeau & Remaudiere 1990). However, its populations may lower

by summer, making the needle yellowing that it causes difficult to diagnose (Brown

& Eads 1967). In the southeastern U.S., Essigella density peaks between September

and March, and falls to its lowest level during June through August (Patti & Fox

1981a), although outbreaks have occurred in May and June (Hood & Fox 1980).

Essigella seem to occur most heavily on young trees, particularly on the lower

east side (Patti & Fox 1981b), which has afternoon shading. In the west, Essigella

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

occasionally damages Christmas tree plantations (California Department of Food

& Agriculture, unpublished data). Sampling (Flood & Fox 1978) and control

regimes (Hood & Fox 1980) have been developed for Essigella in southeastern

U.S. lumber plantations.

Eastop & Hille Ris Lambers (1976) list 21 species in the genus. Lachnus cali-

fornicus Essig (1909) was the first described species, but immediately thereafter

Del Guercio (1909) described the genus Essigella, with L. californicus Essig as its

type species. A second species, E. pini Wilson (1919), was described a decade

later, with two more, E. fusca Gillette & Palmer (1924) and E. hoerneri Gillette

& Palmer (1924), following shortly thereafter. The genus then sat taxonomically

dormant until its synopsis by Hottes (1957), in which 16 new names were created

[E. agilis Hottes, E. braggi Hottes, E. claremontiana Hottes, E. cocheta Hottes,

E. essigi Hottes, E. gillettei Hottes, E. knowltoni Hottes, E. maculata Hottes, E.

monelli Hottes, E. palmerae Hottes, E. patchae Hottes, E. pergandi Hottes, E.

pineti Hottes, E. robusta Hottes, E. swaini Hottes, E. wilsoni Hottes]; another

name, E. oregonensis Hottes (1958), was added a year later.

While working on aphids in California during the 1960s, D. Hille Ris Lambers

attempted to treat Essigella. He concluded (unpublished notes) that the only

available key (Hottes 1957) to Essigella did not work for numerous reasons, and

that the genus needed a major revision using similarly cleared and mounted

specimens. In 1978, he advised me (D. Hille Ris Lambers, personal communi¬

cation) that the systematics of Essigella was extremely difficult, and that he ranked

the genus as one of the most taxonomically problematic among aphids. Since

then, I have analyzed the biological groups in Essigella in relation to their hosts

(Sorensen 1983), suggested a phylogeny (Sorensen 1987a), described three new

species (Sorensen 1988), analyzed the cladistic placement of the genus among the

Eulachnina (Sorensen 1990), assessed phylogenetic changes in shape component

variance between Essigella and its sister group (Sorensen 1991), and presented

analyses deciphering the biological groupings of Essigella on Pinus contorta Doug¬

las (Sorensen 1992a).

The problems of Essigella' s systematics are due to the exceptional reduction

of morphological attributes, over that of an already neotinous subtribe (Sorensen

1990). Retained features in the genus are either extremely variable and overlapping

among species, represent reductions, or involve pigmentation suites, which often

run counter to morphology, and that grade from fully expressed to absent within

populations. In addition, several instances of character displacement seem to occur

among closely related species under sympatry, or near sympatry (Sorensen 1992a,

unpublished data). Discrete characters are unusual within the genus, which shows

many internal homoplasies and few conventional autapomorphies or reliable

synapomorphies (Sorensen 1987a). In Essigella, many characters have transfor¬

mations that are nebulous and unusually difficult to polarize. Traits that are

considered taxonomically meaningful in the genus are often more typical of in¬

traspecific variation in other lachnines, and the converse is also true. Therefore,

interspecific variance in Essigella seems to be antipodal to that encountered among

many other closely related aphids; traits that might be considered to be indicative

of close relationships within the genus, often turn out to show merely superficial

resemblance because of homoplasy, intraspecific variance or apparently faulty

ontogenic physiognomy.

1994

SORENSEN: A REVISION OF ESSIGELLA

Attempts to determine character plasticity in Essigella, by culturing under vari¬

able environmental conditions in the laboratory, failed for several reasons. These

aphids, in contrast to others, often could not be successfully transported to the

laboratory from field. Those Essigella brought to the laboratory alive were difficult

to rear and transfer among host plants. Their laboratory manipulation was ham¬

pered by their solitary, but mobile, habits; to be located, specimens often had to

be jarred from the needles of their host, and frequently did not reestablish on the

plants; a trait noted by Hottes (1957). Electrophoretic analysis of field collected

samples was also problematic: assessing potentially mixed field populations was

difficult because morphological differences among species were not yet understood,

and isozymic responses were unclear.

This revisionary research was based upon newly collected material with proper

host associations from throughout most of the range of the genus, following a

suggestion from D. Hille Ris Lambers (personal communication). In conjunction

with the more traditional approaches to aphid systematics, multivariate analyses

were necessary to determine intra- and intersample variation. Ultimately, pre¬

viously existing Essigella material was studied and fit into the derived taxonomic

scheme without incident. This approach allowed an unbiased initial view of the

genus, which I believe was a prerequisite to its successful revision.

Methods and Philosophy

Collection and Processing of Specimens. — All potential Essigella hosts, includ¬

ing all conifer genera, were sampled during 1977-1979 for this revision (Sorensen

1983). Collections were made from major geographic populations of the aphids’

hosts throughout western North America, north of Mexico (see Critchfield & Little

1966); of these, over 340 host/sites yielded Essigella. Over 7000 specimens, with

an average of over 20 per collection, were collected, processed and studied; ad¬

ditionally, existing material was borrowed from depositories. Elsewhere, I have

listed all locations, with host associations, where my sampling found Essigella

(Sorensen 1983: appendix Al), and have provided a distribution map of all sam¬

pling locations (Sorensen 1983: figs. 1.1, 1.2).

Hottes’ (1957) Essigella specimen processing was poor and resulted in the

obscuring of characters or their erroneous interpretation (e.g., Hottes 1957: 108,

key couplet 1, “tarsal claws not distinctly bifurcated”). As stressed by D. Hille

Ris Lambers (unpublished notes, personal communication), during this project I

have processed and mounted all Essigella specimens using standardized clearing

and mounting techniques. Preparation followed Hille Ris Lambers (1950), and

required sequential boiling in: (a) 95 percent ethanol [5 min], (b) 10 percent

potassium hydroxide [4 min], and (c) saturated chlorophenol until the body con¬

tents were translucent [ca. 7-8 minutes]. Treatment times are important for pres¬

ervation and standardization of subtle pigmentation differences. Processed spec¬

imens were mounted immediately (or rarely stored up to 1 week in chlorophenol)

in Hille Ris Lambers medium (gum arabic 12 g, concentrated glycerine 6.5 g,

chloralhydrate 20 g, distilled water 20 cc). Slides were thick (deep), thus mini¬

mizing common compression artifacts for body width measurements. Immedi¬

ately after mounting, collection numbers were etched into the slides to prevent

any mix-up of samples before labeling.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Analytical Methods.— In addition to conventional analytical techniques used

in aphid systematics, Sorensen (1983) conducted multivariate analyses to circum¬

scribe the biological groupings of Essigella. Those multivariate analyses were

restricted to adult viviparous apterae to limit the influence of seasonal polymor¬

phism and developmental trait variation. Inadequate availability prevented the

separate analysis of other morphs. Initially, only Essigella collected from natural

stands of native hosts were analyzed to limit potentially confusing environmentally

induced variation; later, Essigella from planted stands and nonnative hosts were

incorporated without incident.

For analysis, individuals from samples were first divided into initial groups by

host and geographic location. These initial groups were then circumscribed using

ordination analyses to establish common covariant character patterns among both

the individuals and groups, and to determine the interrelationships among the

initial groups. In the original, exploratory analyses (Sorensen 1983), several subset

combinations of up to 66 morphometric characters were employed; these were

later reduced to a 26 character subset (see Sorensen 1991: table 1) that was used

to circumscribe all final biological groups within the genus.

Quantitative analyses of the initial groupings involved the following steps: (1)

exploratory delimitation of relationships using principal component analysis

[Duncan & Phillips 1980: program PNCOMP] and clustering techniques [Duncan

& Phillips 1980: programs GRAPH and CLUST], followed by reassessment of

the groupings into biological groups; (2) bivariant plotting of various characters

for the deduced biological groups using extended data sets to determine the sim¬

plest character combinations that best allow their separation; (3) corroboration

of inter- and intragroup variance, using the deduced biological groups as “knowns”

in discriminant function analysis [Nie et al. 1975: SPSS, version 7, program

DISCRIMINANT, direct selection mode, Wilks-A criterion]. Sorensen (1992a)

details an example of the use of these procedures in deciphering biological group¬

ings in a species complex within Essigella. After the final biological groups were

assessed, they were cladistically verified, wherever possible, by establishing con¬

ventional autapomorphies or synapomorphies with reference to out-groups (see

Sorensen 1990). Ultimately, a phylogenetic tree was produced for Essigella (see

phylogenetic analysis section).

With respect to the ordinations used (Sorensen 1983), populations of parthen-

ogens can cause problems when assessing their demarcations into groups. Because

aphid clones within samples could not be practically ascertained, exemplars were

employed in this project. Normally, these were restricted to a single individual

per sample. This prevented reduction of effective statistical sample size ( n ); it

thus minimized the miscalculation of intragroup genetic variance, because only

environmental and error components are left to account for observed intragroup

dispersions around centroids as samples become saturated with identical geno¬

types. False low estimates of intragroup genetic variance cause overestimation of

intergroup divergence and phyletic anagenic distance (Sorensen 1987b).

Operational Species Concepts Employed. — Determining aphid species, in gen¬

eral, is often problematic because of their anholocyclic lineages, which often

survive indefinitely in noncontinental climates. I consider an operational aphid

species, sensu Doyen & Slobodchikoff (1974), to be those recombinant individuals

or parthenogenetic populations that share a unique phyletic lineage. This is pref-

1994

SORENSEN: A REVISION OF ESSIGELLA

erably recognized by a conventional autapomorphy. Alternatively, lineages may

be deduced from their congruity of conventional diagnostic synapomorphies or,

if necessary, plesiomorphies, provided they are genetically stable (not induced by

abiotic factors). If nonautapomorphies must be used to deduce a species, its popula¬

tions also must show common distributional and host coincidence; additionally,

species must be multivariately circumscribed following the evolutionary quan¬

titative genetic logic outlined in Sorensen & Foottit (1992), using principal com¬

ponent and discriminant function analyses (e.g., Sorensen 1992a: figs. 3 and 6).

Here, subspecies are recognized only when they impart ecologically or evolu-

tionarily relevant information; they denote divergent or distinct allopatric geo¬

graphic populations (sensu Mayr 1969). This differs from a common usage in

aphid systematics, where a subspecies is often named to denote the sympatric

variance shown by phenotypically deviant individuals, sometimes on the same

host. I consider an operational aphid subspecies to be allopatric and show either:

(a) tighter agglomeration in clustering analyses (e.g., Sorensen 1992a: GRAPH

analyses), or (b) a more restrictive distribution in the attribute space of ordinations,

than do their species within analyses of species-groups (e.g., Sorensen 1992a: fig.

3, as the SNV vs. CAS and RMT distribution in PCA-1).

Taxonomic Key Usage. — The key to Essigella species requires adult viviparous

apterae (subgenital plate present and entire, gonapophyses and siphunculi present)

and, in some instances, their ultimate stadium nymphs (subgenital plate and

gonapophyses absent, abdominal dorsum membranous with distinctly demarcated

plates at dorsal setal bases). Because Essigella species are exceptionally variable,

with overlapping interspecific variation in many traits, calculations of discrimi¬

nant functions (DF), based on several characters, are sometimes required for

morphologically based identification. The key appears to have a reliability of at

least 90%; host plant information is included for more positive identification.

Because of references to subtle pigmentation differences and DF calculations,

remounting of some existing slides may be necessary to use the key. Referral to

paleness or pigmentation in the keys, diagnoses or discussions throughout this

work are to slide mounted material. Slides must be properly cleared, noncom-

pressed, and mounted so that the sagittal plane of the aphids is oriented perpen¬

dicular to the slide. Intrapopulational variance in Essigella, or varying slide prep¬

arations, will require that you judge a circumstance in a key couplet to advance

by alternative routes. If you are unsure when asked about the degree of specimen

pigmentation or slide compression, elect the nonpigmented or compressed slide

option. Questions about pigmentation of the body dorsum refer to the background

intensity, exclusive of setal bases or muscle attachment plates. Slide compression

should be judged conservatively; it is most apparent as a distortion (widening) of

the outline of the head, anterad of the eyes, or the rostral base. (Although body

widths, especially head width, are important in Essigella, they are generally not

used, or are minimized [with warning], in the key due to compression or orien¬

tation faults in many slides.) When asked the number of setae on abdominal

tergum VIII, or the number and pattern of dorsal setae on abdominal terga III—

IV, compare several specimens and use the mode (the latter can be most easily

distinguished on ultimate stadium apterae nymphs, where each seta is on a

scleroite).

DFs are required for specimens whose trait variance occupies an interspecific

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

overlapping range; couplets requiring DFs occur only after those based on non¬

overlapping variation. DF calculation requires (a) the measurement of several

characters, (b) the multiplication of each by a given coefficient, (c) the summation

of all resulting products, and (d) the addition of a constant [for adjustment]. This

grand sum represents a discriminant score (D.S.), whose value represents a thresh¬

old figure for classification of an individual. Where DFs are required, for optimal

classification their scores must be calculated to five figures after the decimal, and

be based on measurements in mm to three figures after the decimal; the latter

may require magnifications of 300-400 x, and error of as little as 5% can result

in misclassifications.

Presentation of Taxonomic and Distributional Data. — The sequence of species

descriptions in this revision reflects their phylogenetic order. Variability and

phenotypic similarity among Essigella species preclude their illustration here,

except for a schematic topological map of dorsal setal positions on the abdominal

terga; my previous Essigella illustrations (i.e., Sorensen 1988: figs. 1-3; 1991: fig.

1) show only that these aphids are relatively linear, varying somewhat in width,

or that traits are variable (Sorensen 1991: fig. 2). The keys provided are the most

reliable means of identification.

I consider all taxonomic names indicated to be new as being legally and orig¬

inally described here; previously, they were considered to be manuscript nomens

in Sorensen (1983), a thesis that is unpublished for nomenclatural purposes under

nomenclatural rules (ICZN 1985: Articles 8-A1, 8-A3, 8-B, and presently 8-C,

9-2, 9-3, 9-4 and 9-6).

Distributional data are listed for each species: use of “JTS” under material

examined indicates J. T. Sorensen as the collector. Distributional maps for Es¬

sigella species depict data locales, differentiated as JTS vs. nonJTS collections,

superimposed over host ranges; the latter were derived from Critchfield & Little

(1966), Little (1971), and Griffin & Critchfield (1972).

Abbreviations and Depositories. — My coded references to Essigella taxa else¬

where (Sorensen 1983, 1987a, 1992a, b) are listed at the end of each of the sections

for each taxon. The U.S. National Museum of Natural History, Washington, D.C.,

is represented as NMNH. The Canadian National Collection, Agriculture Canada,

Ottawa, Ontario, is represented as CNC. Several of Essig’s types are deposited in

the Essig Museum of Entomology, at the Department of Environmental Sciences,

Management and Policy, University of California at Berkeley; in 1993, that de¬

partment was created through an amalgamation of several others, including the

Department of Entomological Sciences, which formerly housed the Essig Museum.

Character Discussion

Essigella are extremely variable aphids. Their normal character variation is

discussed under each species or subgenus, as are some transformations, synapo-

morphies and autapomorphies. This section concentrates on the definitions and

phylogenetic transformations of traits; diagnostic autapomorphies are not dis¬

cussed here unless they show intraspecific variation or represent an independent

state within a transformation series with multiple states.

Aberrations. — Rare Essigella individuals exhibit aberrant traits that are virtually

always expressions of plesiomorphic states that should not occur on their species

(e.g., the number of dorsal hairs on the abdomen). This probably reflects the

1994

SORENSEN: A REVISION OF ESSIGELLA

failure of regulatory genes that normally suppress plesiomorphic phenotypic ex¬

pressions, which is more likely than new creation of a derived state; the suppressed

plesiomorphy, already encoded in the genome, requires merely a gene failure for

expression. There also appear to be similar suppression failures involving onto-

genic phenotypes, where traits of one stage or morph show up erroneously on

another (e.g., allometric differences in relative appendage length). Hottes (1957)

sometimes erroneously considered such individuals to be new species.

Fusion of Terga.— Sorensen (1983 [data used in 1987a], 1988, 1990, 1991,

1992a) previously had misinterpreted the fusion of the meso- and metanota, and

demarcation of abdominal tergum I in Essigella. The correct interpretation of

fusion of the dorsum in Essigella is: head + pronotum fused, meso + metanota

fused, abdominal tergum I free (except E. essigi ), abdominal terga II-VII fused,

abdominal tergum VIII free. Previously, I thought the meso + metanotal fusion

was solely the mesonotum, abdominal tergum I was the metanotum, and abdom¬

inal terga I-VII, instead of II-VII, were fused. This error was discovered when

R. L. Blackman (personal communication) suggested that the autapomorphous

tergal fusion in E. ( E.) essigi involved abdominal tergum I, rather than the meta¬

notum. With the exception of species descriptions in Sorensen (1988), corrected

here, this reinterpretation does not affect the conclusions of any of those studies;

because only the relative definitions of characters, not data, were erroneous. It

does mean, however, that the meso + metanotal fusion in Essigella is an additional

synapomorphy for the genus, beyond those listed in Sorensen (1990); a meso-

metanotal demarcation line is evident in Pseudessigella.

The character definitions in error previously are corrected here, as: old ‘number/

[code] definition error ’ > correction ; but {comments} may be injected or substi¬

tuted for full definitions. Sorensen (1983, 1991: table 1): ‘12/[L2THOR] {length

of mesonotumY > fused meso + metanota; ‘13/[L3THOR] {length of metano-

tum} 9 > abdominal tergum 7; ‘15/[LVABSC],’ ‘16/[NHAB2DT]’ and ‘17/

[NHAB2M]’ {all on abdominal segments II-IV] > III-V. Sorensen (1990: table

1): ‘17/abdominal terga 7-7’ > 2-7. Sorensen (1992a: table 2): ‘ 3/mesothoracic

terg. 17 > fused meso + metathoracic ; ‘7 / metathoracic terg. 17 > abd. seg. 7; ‘10/

abdomen {segments 1-7} L, excluding seg. 8’ > abdomen seg. 2-1 L; ‘25/marginal

seta L on metathorax ’ and ‘54/W between most-mesal pair of dorsal (spinal) setae

on metanotum ’ > abd. terg. 7; ‘28/dorsal (spinal or pleural) seta L on abd. terg.

2’ and ‘29/marginal seta L on abd. terg. 2’ > 3; ‘30/ventral seta L on abd. seg.

2/ ‘41/spiracular plate L on abd. seg. 2’ and ‘57/spiracular plate W on abd. seg.

2’ > 3; ‘ 40/L of presiphuncular abd. {including segment 1}’ > {add} excluding

abd. seg. 7; ‘44/sagittal L of largest ventral abd. sclerite on seg. 2-4 7 ‘45/L of

dorsal (spinal or pleural) setae between dorsal muscle attachment plates on abd.

seg. 2-4, ’ ‘46/N of dorsal (spinal or pleural setae between dorsal muscle attachment

plates on abd. seg. 2-4 ’ and ‘58/largest ventral abd. sclerite W on seg. 2-4 ’ >

3-5.

Sclerotization.— Sclerotization is not equivalent to pigmentation, although

sclerotized areas usually are at least somewhat pigmented. Here, it is the color

independent distinctiveness or thickness of a body surface in comparison to an

adjacent membranous area, as is evident in Essigella' s tergal fusions.

The abdominal dorsum of adult viviparous apterae of Essigella is sclerotized,

in contrast to the other genera of the Eulachnina (Sorensen 1990). This scleroti-

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Vol. 70(1)

zation is universally present in all adults of that morph, although pigmentation

may be quite pale, making it sometimes virtually impossible to detect. When

adult viviparous apterae of Pseudessigella and Eulachnus are superficially com¬

pared to Essigella, they resemble the latter’s ultimate nymphal stadia, which lack

the dorsal sclerotization. In Essigella, the sclerotized dorsum is what should have

been referred to as the “cape” by Hottes (1957); he used the term with reference

to pigmentation for more melanic specimens, noting simply its presence or ab¬

sence, despite its actual gradation. The sclerotization of the abdominal dorsum

of Essigella seems to have occurred at the inception of the genus, and represents

a synapomorphy. It has been strengthened or reduced in various lineages within

the genus, and varies homoplasiously from faint to heavy within species groups.

Examination of the abdominal dorsum of later stadia nymphs of Essigella,

versus adult viviparous apterae, best reveals the latter’s abdominal sclerotization.

On adults, scleroites at the base of the dorsal setae of the abdomen have been

lost or reduced, probably due to incorporation into the general sclerotic field of

the abdominal dorsum; at most, the remnant scleroites appear as indistinctly

bordered darker areas at the setal bases (see pigmentation). In contrast, scleroites

are usually prominent, with well defined borders on the membranous abdomen

of nymphs and alates.

Pigmentation. —Pigmentation represents melanization, and, where quantified,

is expressed here as a density equivalent to the percentage of solid black in a

screen of 52 lines per centimeter (Sorensen 1983). Referral to paleness or pig¬

mentation in the keys, diagnoses or discussions throughout this work are to slide

mounted material. Although sometimes aphid taxonomists (in litt.) place little

weight on minor or trivial pigmentation patterns, in aphids certain pigmentation

suites—denoted here as a covariant series of patterns occurring within phyletic

lineages—are more stable within species, over their seasonal polymorphic changes,

than are simple length ratios for body segments (D. Hille Ris Lambers, personal

communication). Often, major pigmentation suites on viviparous apterae of Es¬

sigella are indicative of one or several species; these are considered to be taxo-

nomically important when they have genetic basis and are monophyletic. Unusual

environmental conditions can cause variation of pigmentation intensity in aphid

species, but not a change in a pigmentation suite. Consequently, reliable pigmen¬

tation is preferred here for identification, where feasible.

Unfortunately in Essigella, the expression of a reliable pigmentation suite that

is characteristic for a species or group, can vary from strongly pigmented to

completely pale within populations; whereas other Essigella species are always

pale. Furthermore, to hamper identification, faint pigmentation in slide mounted

material can be bleached by excessive clearing or prolonged exposure to sunlight.

Geographic variation can also occur in pigmentation suites. For example, many

minor pigmentation tendencies (e.g., subtle variations of shade or intensity of

melanin) recur as homoplasies within Essigella ; these are usually of little taxo¬

nomic interest, except in regard to intraspecific geographic variation.

Two categories of pigmentation suites can be recognized within Essigella for

pigmented individuals of adult viviparous apterae: the expression of shading

among the tibiae, and of the background of the dorsum of the abdomen or entire

body. Reference to body or abdominal pigmentation in the text and keys refers

only to background shading, not to darkened muscle attachment sites and setal

1994

SORENSEN: A REVISION OF ESSIGELLA

bases. The numerous pigmentation suites are discussed in the descriptions, di¬

agnoses and discussions of species.

A general darkening of the body dorsum, as a homoplasious apomorphy, occurs

in E. ( L .) eastopi, E. ( E .) essigi, E. (E.) critchfieldi and E. (E.) knowltoni knowltoni.

Of these taxa, the dorsum of E. ( L .) eastopi is considered to be an autapomorphy

because it shows a unique dorsomedial lightening of the thorax and abdomen

(state A). In contrast, the dorsum is evenly dark (state B) in E. (E.) essigi, E. (E.)

critchfieldi and some E. ( E .) knowltoni knowltoni (Cascade Range); however, other

E. ( E .) knowltoni knowltoni (Rocky Mountains) show a lightening of the frons

and head (state C), or of the entire dorsum. The evenly paler dorsum of E. ( E .)

knowltoni braggi (state D) is assumed to be a apomorphic reversal from state C.

The transformation for the trait is assumed to be A <— B —** C —» D.

The most useful tibial pigmentation suite involves the mesotibiae being at least

subtly, and usually substantially, paler than both the pro- and metatibiae. This

apomorphy is unique to E. (Lambersella), where it is present for pigmented

individuals of all morphs. It can be hard to detect on some darkly pigmented E.

(L.) eastopi, however, because their legs are quite lightened.

Hottes (1957) and Hille Ris Lambers (unpublished notes) erroneously regarded

the presence or absence of pigmented spots that often surround the bases of the

dorsal setae on the abdomen of adult viviparous apterae to be of taxonomic value.

Instead, the spots represent intraspecific or usually intrapopulational variation in

most species. They are seldom present, and then only subtly, in E. (Archeoessigella)

and E. (E.) wilsoni. Within most species, the spots usually occur only on mod¬

erately pigmented individuals, and I suspect their expression is a remnant of a

juvenile factor; they are no doubt homologous with the scleroites that are in¬

variably present in nymphs (see sclerotization).

Abdominal Chaetotaxy. — In Essigella, unlike Eulachnus (D. Hille Ris Lambers,

personal communication), the number and distributional pattern of setae on the

abdominal dorsum appear unaffected by environmental factors. In a principal

component analysis of all Essigella taxa (Sorensen 1983), the number of abdom¬

inal setae show variation that is subordinate only to general-size (component 1).

These setae can be divided into three categories: (a) dorsal setae on terga III-IV,

(b) marginal setae on terga III-IV, and (c) setae on tergum VIII. Within any

species, the characteristic state for each of these setal categories is stable among

all known morphs. Marginal setae, at least in more apomorphic states, do not

appear to show the same type of intraclonal variation as has been found to be

dependent upon the number of sequential generations after the fundatrix in other

aphids (see Crock & Shanks 1983, Blackman et al. 1987). In this study, such

variation would have been detectable as seasonally related variation within natural

populations, which would be in contrast to covariant patterns of other diagnostic

attributes for taxa; to date no such variation has been found.

The dorsal setae of the abdomen are defined here as those setae that occur

between (mesad to) the most sagittally-oriented pair of the three muscle attach¬

ment points on each side of the dorsum of each abdominal tergum. The dorsal

setae can be further broken into two groups: dorsal major setae, which occur

mesally, and dorsal minor setae, which occur more laterally. These subgroupings

(Fig. 1) become apparent when tracing the evolutionary transformations of the

dorsal setae in the genus. Although the setae may be difficult to see in some cases,

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

lateral pair of dorsal muscle

/' attachment plates

\ anterolateral-most

X dorsal minor seta

"0\ / o

•/ *

triangular set of

dorsal major setae

Q •

■ o •

■ ■ o •

□

Figure 1. Schematic maps of approximate positions of dorsal setae on an abdominal terga III and

IV. See comments under abdominal chaetotaxy in the character discussion section. Maps represent

typical relative setal positions, which can vary; the right and left half of each map shows the more

common possible positions. Large gray circles = dorsal muscle attachment plates; each: black square

= dorsal major seta, black circle = dorsal minor seta; white squares or circles (majors or minors,

respectively) show other possible setal positions that are usually absent. A .—Pseudessigella [also see

Sorensen (1991: fig. 3)]. B.— E. ( Archeoessigella ). C.—E. (Lambersella ) expression 1 [i.e., most often

E. ( L .) hillerislambersi]. D.—E. ( Lambersella ) expression 2 [i.e., most often E. (L.) fusca, E. (L.)

eastopi ] (note that a anterolateral-most dorsal minor may move posteromesally). E.—E. ( Essigella )

expression 1 [e.g., E. (E.) essigi, E. (E.) wilsoni, E. (E.) alyeska, E. (E.) critchfieldi, E. (E.) knowltoni].

E.—E. (Essigella) expression 2 (e.g., E. (E.) californica, E. (E.) hoerneri, E. (E.)pini\. Transformation:

A -»• B -> C/D —» E —> F.

1994

SORENSEN: A REVISION OF ESSIGELLA

they are usually well defined and easily traced in the later stadium nymphs of

viviparous apterae (and their adults in Pseudessigella ), where they occur on sclero-

ites in the membranous field of the abdominal dorsum.

In Pseudessigella (Fig. 1A; Sorensen 1991: fig. 3), the dorsal majors occur as

two bilateral, but mesal, groups of three triangularly-arranged setae that flank the

mid-line. Each triangular group has one setae to the anterior and two that flank

it to the posterior. The dorsal minors occur as one to several smaller setae that

are anterolaterad to the dorsal majors. They are posteromesad to the anterad plate

of the sagittally-oriented muscle attachment plates on each segment side (i.e., the

anterolaterad of the three plates). Apparently at least one dorsal minor seta remains

in this position, relative to that muscle attachment plate, throughout the trans¬

formations among the more plesiomorphic Essigella.

In E. ( Archeoessigella ) (Fig. IB), the dorsal major setae remain largely un¬

changed, although occasionally an anterad seta in either triangular set may be

absent. The dorsal minors, however, usually increase in number over their ex¬

pression in Pseudessigella, and several move posteromesally, coming nearer to

the lateral-most dorsal majors. This has the effect of creating what superficially

appears to be a band of setae in somewhat irregular positions across the tergum.

There is, however, usually a retained association between at least one dorsal minor

[the “lateral-most dorsal minor” in descriptions of species here] and the anterolat¬

erad muscle attachment plate.

In E. {Lambersella), the next evolutionary step, two transitional expressions

are found. In the more plesiomorphic arrangement (Fig. 1C), the dorsal majors

remain intact, as do the dorsal minors, although the latter may be reduced in

number. In the alternative state (Fig. ID), among the dorsal majors, an anterad

seta of either, or both, triangular set(s) may be lost; the dorsal minors may be

reduced to two, and the most anterolaterad of these may or may not move

posteriorly, away from its formerly associated position near the anterolaterad

muscle attachment plate. This can result in the occasional occurrence of an in¬

dividual (or population) with a series of only four dorsal (major + minor) setae

occurring in a roughly straight line across the dorsum [a condition that mimics

the first transition in E. ( Essigella ) mentioned below]; usually, however, when

these setae are reduced to four, one of the laterad dorsal minors retains its an¬

terolaterad position. These two expressions in E. {Lambersella) are not necessarily

sequential, and either may occur within populations of any species of that sub¬

genus.

Two expressions also occur within E. ( Essigella ), but these derived states are

sequential. The first (Fig. 1E) typifies all E. ( Essigella ) with eight (or more) dorsals

[i.e., E. ( E .) essigi, E. ( E .) wilsoni, E. (E.) alyeska, and the E. (E.) knowltoni

complex]: the anterad seta of each dorsal major set is lost, leaving only two per

set (four total). In very darkly pigmented specimens [e.g., E. ( E.) knowltoni knowl¬

toni] this is evident, under high magnification on slide mounted material, as a

light spot that is the remnant location of the lost anterad dorsal major. The dorsal

minors are also reduced to two on each side, and the lateral-most has moved back

into a straight line with the remaining dorsal majors. The second expression (Fig.

IF) in E. (Essigella ) occurs as only six (total) dorsals [i.e., E. ( E .) californica, E.

(. E .) hoerneri, E. (E.) pini ]. It is similar to that for the eight E. {Essigella) dorsals,

except the dorsal minors are reduced to one on each side. Aberrations occur for

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Vol. 70(1)

either of these expressions. In either the six or eight state, a suppressed dorsal

major may reappear ahead of the line of setae in its normal anterad position.

Also, in the eight setae state, one or more unsuppressed dorsal minors may occur,

raising the setal count; these may involve a reversion to expression of the anterolat-

erad position.

The marginal setae are defined here as those setae laterad of the sagittally-

oriented pair of muscle attachment points on the dorsum of each abdominal

tergum (see Fig. 1; or Sorensen 1991: fig. 3). Like the dorsals, they are most easily

seen on later nymphs. Among species, marginals may be expressed in a linear

transformation, as states: four to six setae per side, three to five setae per side, or

two setae per side. Their numbers are roughly correlated with the number of total

dorsals. For example, E. (Archeoessigella ) species, which have the most total

dorsals, have four to six marginals per side; in contrast, those E. (Essigella ) species

with only six total dorsals have only two marginals per side. Marginal setal patterns

show the greatest variation within species in more plesiomorphic states. The

marginals of each side may occur in one or two groups, with the latter when their

numbers are higher.

Setae on abdominal tergum VIII apparently have the same approximate trans¬

formation as the dorsals on segments III-IV. They vary among species in a linear

transformation, from: 10-16 setae in two rows; to 8-12 setae in one or two rows;

to 6, or occasionally 8 (rarely to 10), setae in one or occasionally two rows.

Dorsal Setae on the Metatibiae. —These setae often show considerable inter-

and intraspecific variation in Essigella. In a principal component analysis of all

Essigella taxa (Sorensen 1983), the length of dorsal setae on the metatibia, along

with all other setae, show variation that is subordinate to general-size (component

1) and the number of abdominal setae (component 2). Tentatively, the dorsal

setae of the metatibia are considered taxonomically useful only for apterous morphs.

Their variation in Essigella contrasts with that of Eulachnus and other Lachninae,

where their length appears to be more stable within species. This difference par¬

tially was responsible for the failure of previous attempts to circumscribe and key

Essigella species (see Hottes 1957).

Hille Ris Lambers (unpublished notes), criticizing Hottes (1957), suggested

“constant characters” within Essigella included “the length of tibial setae, but

not their being blunt”; he also stated “in the same species more or fewer of the

tibial setae may be blunt which accounts for a rather large variation in setal length

in some species.” I consider those statements to be erroneous. The retention of

incrassate tips regardless of setal length, along with other characters, unifies the

E. (E.) knowltoni group. Hottes (1957) erroneously defined his species on narrowly

restricted setal length ranges; Hille Ris Lambers thought Hottes’ use of setal length

confused blunt versus sharp tipped setae, which although Hille Ris Lambers

correctly viewed as a continuum, he unfortunately disregarded as being of any

taxonomic value in Essigella. I have studied variation of the tip structure among

the dorsal metatibial setae for Essigella, including scanning electron microscopy

work, and recognize several degrees of expression of bluntness among tips (un¬

published data); although of some taxonomic merit, this finer level delineation is

not presented, because it cannot be used pragmatically to discriminate among

most species.

Three aspects of the dorsal setae on the metatibiae are recognized and cate-

1994

SORENSEN: A REVISION OF ESS1GELLA

gorized here: (a) length dimorphism within individuals and species, (b) variability

in the range of setal length within species, and (c) variability in the condition of

setal tips within species. Only the characteristic patterns of expression of these

setae are considered valid synapomorphies within Essigella. Generally, these setae

are long in other Lachninae, and their length is obviously homoplasious within

the subfamily. Because of potential confusion concerning reference to particular

setae, only those setae on the central one-third of the metatibia are treated here;

reference is usually to only the longest of dorsal setae for that section (generally

the dorsal metatibial setae are shorter and more incrassate proximally, and longer

and sharper distally).

The plesiomorphic state (state A) for dorsal setae of the metatibia within Es¬

sigella is short (ca. 0.3-0.7 x tibial diameter) with incrassate tips; as in Pseudes-

sigella, E. (Archeoessigella ), and E. (E.) essigi. From this plesiomorphic “short,

incrassate” condition, three independent transformation series are hypothesized

within Essigella. The first involves elongation of setae to a continuous length

range of ca. 0.3-2.0+ x tibial diameter, with the tips of shorter setae incrassate

and longer setae sharp. This intermediate state (state B) represents the normal

relationship for setal length and tip expression in aphids. Transformation contin¬

ues to an ultimate apomorphic state (state C) for this series, which shows an

increase in the range of length variation to ca. 0.1-4.0+ x tibial diameter, and

an increase in length variability within populations that I suspect is genetic and

consider a weak synapomorphic character. This transformation is A —» B —» C.

The second independent transformation involves a single step elongation of the

setae (state D) to a continuous length range of ca. 0.3-2.0+ x tibial diameter,

but without the development of sharp tips. These setae are always incrassate,

regardless of length, and are considered a valid synapomorphy for the E. (E.)

knowltoni group. This transformation is: A -* D.

The third independent transformation involves setal elongation, to a dimorphic

length range spanning ca. 0.3-4.0+ x tibial diameter (state E). This dimorphism

can occur as a discrete length difference among different individuals of a popu¬

lation, or may be expressed on single aphids as an abrupt change in setal length

on the central part of the metatibiae; it is restricted to E. (Lambersella), and

appears to have ecological relevance between species of that subgenus in sympatry

as a character displacement (unpublished data). Absence of the dimorphism in

E. ( L .) hillerislambersi may be a secondary loss for this accommodation. This

transformation is A —* E. Potentially confusing variation occurs in E. ( Essigella )

californica, where a minor increase in length of the dorsal setae is rarely evident

on the distad one-third of the metatibiae; this is not considered homologous to

the condition in E. {Lambersella).

Ventral Abdominal Sclerites. —These sclerites represent attachment plates for

muscles on the abdominal venter. Their size and shape may, therefore, have a

functional relationship with the degree of sclerotization (not pigmentation) of the

abdominal dorsum. Due to the diminished size and irregular variation of these

ventral sclerites on more posterad abdominal segments, only segments III-IV are

considered for taxonomic (identification) use. The sclerites are measured at their

maximal length, along the anteroposterad axis, of the largest such sclerite occurring

on abdominal segments III or IV. Unfortunately, the relative shapes and variance

of these sclerites must be studied among species to be adequately comprehended.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

As with the dorsal setae on the metatibiae, it is the qualitative pattern of

expression of the ventral abdominal sclerites within populations, species, or spe¬

cies groups, that is considered taxonomically meaningful. In Pseudessigella (Sor¬

ensen 1991: figs. 2a-h), the ventral abdominal sclerites can be either uni-, bi-, or

tripartite; if broken, the posterad section is relatively large and irregularly ovate,

and the more anterad section(s) may be reduced and/or irregularly linear. In most

species of less derived Essigella, these sclerites are subcircular to subquadrate

[e.g., relative difference, Sorensen (1991: figs. 2e vs. 2f as bottom sclerite only of

each, respectively)] (state A); this state occurs in E. (Archeoessigella), E. ( Lam-

bersella ) and the more plesiomorphic species of E. {Essigella ). To achieve this

shape during evolution, it is unclear if a linear sclerite simply shortens, or if it

breaks into multiple subsclerites and loses the more anteriad of these. Alterna¬

tively, in E. (Lambersella) these sclerites can be relatively linear [e.g., Sorensen

(1991: figs. 2c-d)], which matches their most linear unbroken development in

Pseudessigella, or they can be nearly absent; these alternative expressions are

treated as state A here also.

Within E. {Essigella), several species show reduction of these sclerites, with

expression varying from (at most) irregular, small quasi-stellate shapes through

apparent absence (state B). This is considered homoplasious within the subgenus.

Within the clade involving the E. {E.) knowltoni group, these sclerites ultimately

become relatively enlarged and vary from subcircular or subquadrate to subellip¬

tical [e.g., latter, Sorensen (1991: fig. 2a)] (state D); an intermediate expression

(state C) exists for E. (E.) alyeska, however, in which the sclerites vary from

between states B and D within populations. The transformation is considered to

be A —» B —> C —> D, but it could be independent among the latter three states.

Body Widths.— Body shape differences occur within the genus and primarily

involve relative width. Width characters are usually unreliable on most slide

mounted material, due to compression artifacts. The standardized mounting tech¬

nique described earlier substantially reduces body distortion. Therefore, width

measurements were used in analysis, but are avoided in keys and diagnoses, which

must be applied to unstandardized slides.

Head width is measured between the most laterad rims of the bases of the

antennal sockets. This anterad measurement minimizes the effects of compression

that are more likely to occur posteriorly. It also enhances recognition of com¬

pression, because the measurement line is adjacent to the clypeal region and the

anterad outline of the frons; distortion of these regions is relatively noticeable

when they are compressed.

Relatively slight increases in width within species groups are homoplasious in

this genus. Only the discrete and statistically significant broad body shown by the

E. (E.) knowltoni group and E. (E.) alyeska is considered to be a valid synapo-

morphy. Although Moran (1986) warns against using such ecologically influenced

traits, it is interesting that E. (E.) hoerneri, a relatively broad Essigella whose

width correlates with its pinyon pine host’s needle width, is correctly placed with

E. (E.) californica, rather than the Series B E. {Essigella), in several discriminant

function analyses (e.g., Sorensen 1992b: figs. 2a-b, 3) of the genus. This dem¬

onstrates the acceptable multivariate use of body width for classification (but not

necessarily identification) within Essigella.

Lengths and Shapes of Appendage Segments. — Determination of the polarities

1994

SORENSEN: A REVISION OF ESSIGELLA

for transformations of antennal segment lengths in Essigella is difficult. The re¬

duction from six to five antennal segments is a synapomorphy for Essigella and

Pseudessigella, but is not unique in the Aphididae. In a principal component

analysis among all Essigella taxa (Sorensen 1983), antennal segments III, IV and

to a lesser extent V, load moderately on the second component. That vector orients

largely to setal number on the abdominal dorsum, where polarity is clear. On the

vector, however, the antennal segment lengths and abdominal setal numbers load

in opposition; consequently, an increase in the relative length of antennal segments

probably can be interpreted as apomorphic within the genus, as the abdominal

setal number decline (Sorensen 1991, Sorensen & Foottit 1992).

Allometric variation in the length of the metatibiae, which is associated with

different morphs and stages in Essigella, is confusing. Hottes (1957) and Hille

Ris Lambers (unpublished notes) regarded relative tibial lengths as constant among

species in the genus. In aphids generally, there is a tendency for alates, because

of their generally longer legs, to have relatively longer metatibiae in comparison

to body length than do adult viviparous apterae. The converse is often true of

later stadia nymphs of viviparous apterae, which generally have relatively shorter

metatibiae than do their apterous adults. Variation along this morph factor is

discordant in Essigella, however. In some E. (Archeoessigella) and E. ( Essigella ),

aberrant adult viviparous apterae exist that retain the relative metatibial length

characteristic of the juvenile stages of their species. Several of Hottes’ synonyms

can be attributed to this aberrant variation among adult apterae [see the discussion

of E. (E) californica\. Contrastingly in E. (Lambersella ), metatibial length is more

stable within species; in that subgenus, however, allometric shifts along ontogenic

factors, among species, sometimes differentiate the species in sympatry through

character displacement.

The comparative length of metatarsal segments varies in Essigella. In E. (Ar¬

cheoessigella), the metabasitarsus (first hind tarsus) is relatively short in regression

compared to the metadistitarsus (second hind tarsus); a plesiomorphy reflected

to a greater degree in Pseudessigella. Apomorphic elongation of the metabasitarsus

occurs as a homoplasy in E. (Essigella) and E. (Lambersella), but reliable trans¬

formation of this homoplasious bivariate is difficult to ascertain; see Sorensen

(1991) for a discussion of this trait.

In lateral view, the shape of the profemur of more primitive Essigella resembles

that of Pseudessigella. In the latter, the dorsoproximal base of the femur is strongly

swollen and arched. A similar, but less pronounced, swelling is evident in species

such as E. (A) kathleenae, and E. (E) pini, among others. In most Essigella,

however, the femur usually assumes a more cylindrical shape with elongation in

response to increases in body size in various lineages, no doubt as a allometric

size transformation. This trait is not employed in identification or phylogenetic

assessments, because its variation is inadequately known and is difficult to char¬

acterize; it cannot be measured satisfactorily on slides because it is usually oriented

in the dorsoventral axis.

Rostral Characters. — The rostrum of Essigella is retractile; consequently, rostral

length is measured as the length of the stylets, which are fixed. Unfortunately, on

slide mounted specimens the stylets can be withdrawn from the rostrum, and

curved, making accurate measurement difficult. Stylets are measured from the

sclerotic, basal apophyses in the clypeal region to their unbroken distal tips.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Essigella (E.) hoerneri shows the greatest apomorphic increase in stylet length in

response to the exceptional needle fascicle width of its piny on pine hosts. Mea¬

surement of the ultimate rostral segment includes the short, light-colored distal

cap and the basal apophyses. Univariate or bivariate use of the ultimate rostral

segment has not proven sufficiently reliable for consistent employment.

Caudal Protuberance. — Although Hottes (1957) used the median protuberance

on the cauda as a diagnostic character, I have avoided this due to its variation

and the potential for orientation artifacts on slides where the protuberance is

obscured when the cauda points up. The caudal projection shows undoubtedly

homoplasious reduction trends, but its transformation and polarity are confusing

among species groups. Essigella (E.) pini shows the greatest development of the

caudal protuberance, with the protrusion sometimes quite strongly pointed; this

undoubtedly accounts for the use of the character as an ultimate, but problematic,

diagnostic for that species in Hottes’ (1957) key.

Nymphs. — In later stadia nymphs of viviparous apterae (not prealatae), a pair

of bilateral sclerotized plates occur that surround the muscle attachment plates

on the mesonotum; these may be large or small, depending upon the species.

When large (e.g., their diameter approximates the length of the eye), the invasive

sclerotizations of these plates extend from the muscle attachment sites to engulf

neighboring setal bases. The mesonotal sclerotization on nymphs can be extremely

faint, especially in the E. (Archeoessigella ), where the enlarged plates can be

difficult to see because of their light pigmentation. This sclerotization probably

has a similar history to that of the abdominal dorsum of adult viviparous apterae.

Presence of the developed plates may be a synapomorphy unique to Essigella

among the Eulachnina. The enlargement of these plates is treated as a plesio-

morphy within the genus, however, and secondary losses of the plates are con¬

sidered to be weak synapomorphies. In E. (L.)fusca, where the plates are normally

enlarged, one late stadium nymph, within a large and otherwise normal sample,

shows the loss of this invasive sclerotization. With this exception, the character

appears quite stable among species; therefore, considering the loss state to be

plesiomorphic on the basis of that single occurrence (i.e., a suppression failure)

would require unacceptably strong homoplasy for the character. Nevertheless,

the loss of these invasive sclerotizations, so that neighboring setal bases are free,

appears to be a homoplasious apomorphy within E. (Essigella ) for E. ( E.) Cali¬

fornia, E. (E.) hoerneri, E. (E.) wilsoni and E. (E.) alyeska.

Alatae. —Essigella alates are poorly known, and in several instances they are

unknown. They appear to have few reliable diagnostic characters to identify them

beyond species group. Characters often used within other genera, such as the

number, shape or arrangement of secondary rhinaria on the antennae, usually

show more intra- than interspecific variance in Essigella. Although Essigella alates

normally have membranous abdominal terga, aberrants exist that show the normal

sclerotic patterns of abdomens for their respective viviparous apterae or oviparae.

Because knowledge of alate variation is poor, all statements concerning alate traits

are tentative.

Although venation is often of quite questionable taxonomic use in aphids (V.

Eastop, D. Hille Ris Lambers, personal communications), it may be used in

Essigella, with great caution. For instance, in Essigella the medius may have one

(or rarely two) furcation(s), or may be single. The furcation may arise on the

1994

SORENSEN: A REVISION OF ESSIGELLA

proximal, central or distal one-third of the vein. A single medius is most probably

apomorphic; if so, then the only synapomorphy appears to be for E. {E .) pini and

E. {E .) essigi. In both species, however, the vein can vary, uncommonly, to having

a furcation on its distal one-third. Moreover, the medius is also rarely expressed

as a single vein in aberrant alates of the E. (E.) knowltoni group; thus, polarity

remains questionable.

Other variation of the medius involves the strength of expression of this entire

vein system. Where the alates are known in E. (Lambersella), the medius is usually

only faintly present along its entire length. This reduction is considered a weak

synapomorphy. There are also differences involving the junctions of the anal and

cubital veins with the radius. These can be expressed by the distance between the

bases of the anal vein and the cubitus, along the radius, or by the truncated angle

between them. The character is variable and tentatively considered unreliable as

a diagnostic. An aberration displayed by several Essigella species is a darkened

band that posteriorly parallels the radius.

The epicranial suture may be of use taxonomically. The suture appears to be

most prominent and stable in E. (E.) californica and E. (E.) hoerneri, but varies

in presence and expression among other species.

Oviparae. — Although the oviparae of all Essigella species are not known, among

those that are, three conditions exist for the sclerotization/fusion of the abdominal

dorsum: (state A) terga II-VII are fused, but I and VIII are free; (state B) abdominal

terga II-VI are fused, but I, VII and VIII are free; and (state C) all abdominal

terga are free with independently banded sclerotizations. It is unclear whether

state A or B is the most plesiomorphic because both occur in E. ( Archeoessigella );

the transformation could be either A-^B^CorA^B— * C. State A occurs

in E. ( Archeoessigella) kathleenae, in the E. ( Essigella) knowltoni species-group,

and usually in E. {E.) pini. State B occurs in E. {Archeoessigella ) kirki, in E.

{Lambersella), and rarely in E. (E.) pini. Therefore, the character is necessarily

homoplasious, with state A either as a plesiomorphy, which requires a reversal

in E. {Essigella), or as an apomorphy, which requires it to be gained independently

in E. {Archeoessigella) and E. {Essigella). The complete loss of tergal fusion in

state C, for the E. {E.) calif ornica group, is considered a weak synapomorphy.

Uncommon oviparae of species with the banded abdominal terga of state C can

show near fusion of terga II-V or II-VI. This suggests an apparent plesiomorphic

aberration approaching state B; if so, it appears C is apomorphic to B. No re¬

versions from B or C to A are apparent; however, because E. {E.) pini usually

shows fusion of abdominal terga II-VII, but with VI rarely free, this may be

evidence for plesiomorphy in state B?

Key to the Eulachnina Genera

la. Antennae of adult virginoparous apterae 6-segmented.

. Eulachnus del Guercio

lb. Antennae of adult virginoparous apterae 5-segmented. 2

2a. (lb) Tarsal claws with single, simple tips. Adult apterae with tergum of

abdominal segments II-VII membranous.

. Pseudessigella Hille Ris Lambers

2b. Tarsal claws incised, with double tips. Adult apterae with tergum of

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

abdominal segments II-VII fused, very lightly to heavily sclerotized.

. Essigella del Guercio

Essigella Del Guercio, 1909

Essigella Del Guercio, 1909, Riv. patol. Veg., Padov, n.s. 3: 329.

Lachnus Burmeister, 1835 (in part), Hardbuch der Entomologie, Berlin, 2: 91

(genus attributed to Illiger); Essig, 1909, Pomona J. Entomol., 1: 1-4.

Type Species.— Lachnus californicus Essig, 1909, Pomona J. Entomol., 1: 1-4;

by monotypy.

Viviparous Apterae. — Body elongate, linear to linear-ovate. Antennae 5-segmented; processus ter-

minalis short; accessory rhinaria on terminal antennal segment proximad, not directly against primary

rhinarium. Head wider than long, fused with pronotum, or nearly so. Eyes without distinct triom-

matidia. Rostrum retractile; last rostral segment short, blunt, tip nonfunctionally articulated (if at all),

accessory setae absent. Meso- and metanota fused dorsally. Abdominal dorsum lightly to heavily

sclerotic; tergum I usually free; terga II-VII fused; tergum VIII free, represented by single, entire

sclerotized field not apparently formed from fused lateral sclerites associated with setal bases; pig¬

mentation variable; dorsal setae on segments III—IV in 1 or 2 often irregular rows. Siphunculi rep¬

resented as rimmed pores to short truncated cones, without setae, incorporated into dorsal sclerotic

field of abdomen. Cauda rounded, frequently with short, rounded to pointed, median protuberance.

Profemora cylindrical-tapering, to dorsoproximad base slightly swollen. Tarsal claws incised, bifid;

dorsal tip blunt, ventral tip sometimes slightly projecting, blunt to sharper.

Other Morphs.— Known fundatrices and males lacking siphunculi. Known oviparae and males

apterous. Known alatae with radial sector short, straight; forewing medius distinct to apparently absent,

single or with 1 furcation.

Diagnosis.— See the key to the Eulachnina genera and apomorphies section

below.

Taxonomic Placement. —Essigella, along with Pseudessigella Hille Ris Lam-

bers, 1966, and Eulachnus Del Guercio, 1909, comprise the subtribe Eulachnina

(Sorensen 1990) of the tribe Cinarini, subfamily Lachninae; the subtribe is con¬

sidered highly derived within the subfamily. The immediate sister-group of Es¬

sigella is Schizolachnus\ which Lampel & Burgener (1987) suggest placing, along

with the three eulachnine genera, in a single tribe, the Schizolachnini. Sorensen

(1990), however, places Schizolachnus in a separate subtribe, the Schizolachnina.

For commentary on the taxonomic relationships of related genera, and previous

tribal/subtribal assignments, see Sorensen (1990).

Distribution.—Essigella is the only native Nearctic representative within the

subtribe Eulachnina, although it has recently been introduced into Europe, in

France (Turpeau & Remaudiere 1990) and Spain (Seco Fernandez & Mier Durante

1992). The other eulachnines, Pseudessigella and Eulachnus, are native to the

Palaearctic; the former is known only from a single collection in the Himalayas

of Pakistan (Sorensen 1991), but the latter has been introduced to the Nearctic

where it occurs largely on cultivated Old World pines.

Apomorphies. — The three Eulachnina genera share these synapomorphies: body

form linear; triommatidia of compound eye undifferentiated; ultimate rostral

segment short and blunt, tip nonfunctionally articulated (if at all); accessory setae

on ultimate rostral segment absent; setae on siphunculi absent; primary rhinarium

without chitinous ring border; and accessory rhinaria on terminal antennal seg-

1994

SORENSEN: A REVISION OF ESSIGELLA

ment proximad and not directly against primary rhinarium. Essigella and Pseu-

dessigella share these synapomorphies: reduction from six to five antennal seg¬

ments; and abdominal tergum VIII represented by a single, entire sclerotized field

that is not apparently formed from fused lateral sclerites that are associated with

the dorsal setae bases.

Essigella is the most derived genus of the subtribe (Sorensen 1990) and has

these autapomorphies: tarsal claws bifid; entire dorsum sclerotized; head and

pronotum fused; meso- and metanotum fused dorsally; abdominal tergum I usu¬

ally free (but at least partially fused [laterally] to metanotum as an autapomorphy

in one species); abdominal terga II-VII fused. Another tentative autapomorphy

for Essigella is a complete loss of the siphunculi in both the fundatrix and male,

where these morphs are known; they are yet unknown for Pseudessigella and,

therefore, the trait could be synapomorphic at that level. All Essigella have def¬

initely incised tarsal claws, with the resultant presence of an endodontal lobe,

despite Hottes’ (1957) comments to the contrary; Hille Ris Lambers (personal

communication, unpublished data) correctly interpreted Hottes’ (1957: 108, key

couplet la) statement of “Tarsal claws with ends not distinctly bifurcated” as

erroneous, and due to over-processing in caustics during slide preparation.

Subgenera. — Three Essigella subgenera are recognized and described here; see

the phylogenetics section for commentary. Their compelling separation requires

discriminant function analysis of morphometric traits because considerable over¬

lap in univariate traits exists among Essigella species (Sorensen 1983). Demar¬

cation of these subgenera was made from an evolutionary perspective (see Sor¬

ensen 1992b) that includes Pseudessigella as an anagenic distance reference. Because

many other aphid subgenera can be distinguished by single characters, their dif¬

ferentiation may be under the control of a single, or fairly limited number of,

genes. As a result, such univariately defined subgenera probably display less genetic

divergence than do the Essigella subgenera, among which realignments have

occurred for large suites of genes (Falconer 1981, Sorensen 1991, Sorensen &

Foottit 1992) that are responsible for their multivariate divergence. See Sorensen

(1991) for a discussion of the multivariate evolution of the shape component

among traits between Pseudessigella and Essigella, and among some Essigella

groupings.

The phylogeny for the genus indicates Archeoessigella, the least derived sub¬

genus, is separated (as Fig. 13: node 1) from Pseudessigella by 18.9 o units (see

phylogenetics section). Lambersella is separated from Archeoessigella by 2.08 er

units (as Fig. 13: intemode 2-3). Essigella ( Essigella ), the most derived subgenus,

is separated from Lambersella by 4.22 a units (as Fig. 13: internode 3-7). All

three of these anagenic distances are significant, at a = 0.05, as evolutionary gaps

between genus-[or subgenus]-level species assemblages (see phylogenetics section).

Also, all three subgenera are phylogenetically convex (sensu Duncan 1980, Es-

tabrook 1986), with Lambersella and E. {Essigella) as monophyletic groups.

Although the Essigella subgenera are quite valid biologically and evolutionarily,

and their status as subgenera gives them the same nomenclatural rights as genera,

they are described here with relevance only for intrageneric hierarchy. Because

the anagenic distances among the Essigella subgenera are considerably shorter

than among the genera in the Eulachnina, I recommend that these subgenera never

be elevated to the status of full genera through taxonomic inflation.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Etymology. — The genus was named by Del Guercio (1909) after E. O. Essig,

who collected and described its first species as Lachnus californicus Essig.

Material Examined.— All taxa proposed here, plus all Eulachnina and Schizolachnina taxa listed

in Sorensen (1990: in Phylogenetic Construction sections Ingroup Material Examined and Outgroup

Selection).

Key to the Subgenera of Essigella

This key is intended only for properly cleared, slide-mounted virginoparous

apterae, and is meant for populations and species, rather than individuals. Key

intraspecific samples with several (preferably n = 10+) individuals to account for

variance. Individuals should be keyed using the key to Essigella species.

la. Abdominal terga III-IV with dorsal setae in a single [or at most a very

slightly staggered] row; lateral-most seta normally absent. Populational

mean for number of dorsal setae on abdominal terga III-IV normally

6 or 8, mean number on abdominal tergum VIII normally 6, sometimes

8, never 9 or more [if mean on terga III-IV is 8-10 and the mean for

tergum VIII is 8, then : (a) developed pigmentation suite for tibiae

described in couplet 2a (below) never occurs in any population; and

(b) populational mean for the ratio of length of the metadistitarsus to

metabasitarsus is 1.73:1 or less; and either (cj body relatively broad

with at least some populations with specimens whose longest dorsal

setae on the central one-third of the metatibiae exceed 1.5 x metatibial

diameter and remain incrassate regardless of length; or (c 2 ) metanotum

and abdominal tergum I fused at least laterally; or (c 3 ) mesonotum of

later stadia nymphs of apterae with area immediately surrounding mus¬

cle attachment sites membranous and bases of neighboring setae not

on a sclerotized plate contiguous with the muscle attachment sites; or

(c 4 ) mean number of marginal setae per side on each of abdominal

terga III-IV is 2; or (c 5 ) primary rhinarium on terminal antennal seg¬

ment exceptionally distad with distance from tip of processus terminalis

to distal face of rhinarial rim less than 0.5 x diameter of rhinarium,

and distal face of rhinarial rim usually perpendicular to longitudinal

axis of antennal segment, and rhinarial membrane usually conspicu¬

ously protuberant]. Essigella (Essigella ) del Guercio

lb. Abdominal terga III-IV with dorsal setae in a double [or strongly stag¬

gered] row; lateral-most seta normally present. Populational means for

number of dorsal setae on abdominal terga III-IV and tergum VIII

normally at least 8 or more, never 6 [if means on terga III-IV and

tergum VIII are 8-10, then either, (a) any developed pigmentation suite

described in couplet 2a (below) may or may not occur in any population;

or (b) populational mean for the ratio of length of the metadistitarsus

to metabasitarsus is 1.70:1 or greater; but (c) none of conditions Cj-c 5

in couplet la ever exist]. 2

2a. (2a) Populational mean for the ratio of length of the metadistitarsus to

metabasitarsus is 1.69:1 or less, but usually under 1.65:1. Intraspecific

pigmentation suites ranging from pale (unpigmented) to heavily pig¬

mented, often within populations, but if developed (even subtly) then

1994

SORENSEN: A REVISION OF ESSIGELLA

(a) pro-, meso- and metatibiae, respectively, pigmented relatively heavi¬

ly, lightly and heavily [in a dark-light-dark pattern], or (b) body dorsum

with darkened pigmentation but with lightened longitudinal stripe in

dorsomedial region of thorax and abdomen, or (c) thoracic and ab¬

dominal terga mottled with dorsal setal bases pigmented. In any pop¬

ulation, longest dorsal seta on central one-third of metatibia varying

from incrassate and short to long and either sharp or blunt tipped, but

if longer than 1.0 x metatibial diameter then they are not incrassate.

Populational means for number of dorsal setae: (a) on each of abdom¬

inal terga III-IV usually 10 or less [occasionaly 11], but if mean more

than 10 then at least some individuals with 9 or less; and (b) on ab¬

dominal tergum VIII usually 9 or less [occasionally 10], but if mean

more than 9 then at least some individuals with 9 or less.

. Essigella (Lambersella ) NEW SUBGENUS

2b. Populational mean for the ratio of length of the metadistitarsus to metaba-

sitarsus is 1.70:1 or greater, but usually over 1.75:1. Intraspecific pig¬

mentation suites ranging from pale (unpigmented) to very subtly pig¬

mented, but when pigmentation is subtly developed it is generally even

and never as in couplet 2a. In any population, longest dorsal seta on

central one-third of metatibia always incrassate and less than 1.0 x

metatibial diameter. Populational means for number of dorsal setae:

(a) on each of abdominal terga III-IV usually 11 or more, but if mean

less than 11 then at least some individuals with 13 or more; and (b)

on abdominal tergum VIII usually 10 or more, but if mean less than

10 then at least some individuals with 12 or more.

. Essigella (Archeoessigella) NEW SUBGENUS

Essigella (. Archeoessigella ), NEW SUBGENUS

“Essigella (Archoessigella )” Sorensen, 1983: 58 (unpublished manuscript name,

note different spelling) Ph.D. Thesis, University of California at Berkeley, Berke¬

ley, California. 605 p.

Type Species.—Essigella kathleenae Sorensen, 1988.

Viviparous Apterae. —Morphology: Body slender. Meso- and metanota fused dorsally; abdominal

tergum I free. Dorsal setae (majors and minors) between muscle attachment plates on abdominal

segments III-IV in 2 often irregular rows (see Fig. 1B); lateral-most minor dorsal setae on each side

anterad (rarely not) of its immediately mesad neighbor. Abdominal terga III-IV each with 10-16

dorsal (major + minor) and 4-6 (per side) marginal setae; tergum VIII with 10-14, rarely 7-9, setae.

Longest dorsal seta on central one-third of metatibiae less than tibial diameter, tips incrassate; these

setae of nearly equal length along metatibiae, not dimorphic. Ventral abdominal sclerites on segments

III-IV large, subquadrate or subcircular, not rudimentary. Species means for length ratio of metadisti¬

tarsus to metabasitarsus varying between 1.81:1 to 2.05:1. Pigmentation: Body dorsum unicolorously

pale; bases of dorsal setae of abdomen concolorous with surrounding terga. All tibiae equally pigmented,

usually pale to rarely subtly dusky.

Diagnosis.— See the key to the subgenera of Essigella.

Discussion.— This plesiomorphic subgenus is paraphyletic, but convex (sensu

Duncan 1980, Estabrook 1986); no qualitative synapomorphies exist that uniquely

define the group. It characteristically has a high ratio for the metabasitarsus:

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70 ( 1 )

metadistitarsus length, relatively many dorsal and marginal setae on abdominal

terga III-IV and VIII, metatibial dorsal setae that are short and incrassate, no

developed pigmentation suites, and species that are functionally monophagous

and restricted to pine species in Pinus (Strobus ), section Strobus, subsection Strobi.

Except for some minor differences in placements of certain dorsal setae on the

abdominal terga III-IV, intriguingly, all these characteristics are shared by Pseu-

dessigella to a great degree. Archeoessigella was named because it differs signifi¬

cantly from Lambersella in several respects, and the two each have distinctly

different host associations.

Similarities between the Archeoessigella species are relative plesiomorphies.

The phylogenetic tree (Fig. 13), based on all 15 available dimensions of discrim¬

inant space, shows E. {A.) kirki to branch from node 1 (distance = 0) as the most

primitive Essigella. However, when the multivariate shape-component differences

for traits between Essigella and Pseudessigella were analyzed on the more dom¬

inant shape vectors, Sorensen (1991) found E. {A.) kathleenae to be generally

more similar to Pseudessigella than to the remaining more derived Essigella, and

he found E. (A.) kirki to be intermediate between those groups; he noted each

Archeoessigella species was less similar to one another than either was to Pseu¬

dessigella or to the more derived Essigella. The closer proximity between Pseu¬

dessigella and E. (A) kathleenae is also reflected on the second-most dominant

minimum selective mortality vector (Fig. 14: DF2). A single, conventional, qual¬

itative trait, the fusion of the abdominal dorsum in oviparae, sheds only vague

light on the problem because its transformation and polarity are uncertain [see

oviparae under the character discussion section].

Coded References to this Taxon. — Sorensen (1983) referred to this taxon under

the manuscript name “ Essigella (Archoessigella ).” Sorensen (1987a) referred to

the assemblage that comprise this taxon as group “I” or, with reference to its

subcomponents, as “J-K”; in Sorensen (1992b), the latter refers to it.

Etymology. — “Archeo-” (Greek) = ancient; the name reflects the old and

primitive status of the subgenus; coincidentally, the compounded name includes

“-eoessig-” for E. O. Essig.

Material Examined.—Essigella (A.) kathleenae, E. (A.) kirki.

Essigella {Archeoessigella) kirki Sorensen, 1988

Essigella kirki Sorensen, 1988: 121, Pan-Pacif. Entomol., 64: 121-124.

Essigella “hottesi ” Sorensen, 1983: 60 (unpublished manuscript name) Ph.D.

Thesis, University of California at Berkeley, Berkeley, California. 605 p.

Type Series. — Holotype. vivip. apt.; on slide with 3 paratype vivip. apt., ho-

lotype at lower left (8 o’clock position); data: NEW MEXICO. SANTA FE Co.:

ca. 30kmNEofSantaFe, hwy475, 3100 m, 10 Aug 1978, J. T. Sorensen (78H55),

Pinus flexilis James. Holotype retained in Sorensen collection, eventually to be

deposited in The Natural History Museum, London. Paratypes (all same data as

holotype): 19 vivip. apt. on 5 slides including holotype slide. Paratype slides

deposited: 1 slide in NMNH, Washington, D.C.; 1 slide in CNC, Ottawa, Ontario;

2 slides in Sorensen collection.

1994

SORENSEN: A REVISION OF ESSIGELLA

Viviparous Apterae.—Morphology: Body length: 1.73-2.13 (1.92 ± 0.13) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 95-133 (117 ± 10) p, processus terminalis: 28-45 (37 ±

5) p; IV: 70-91 (82 ± 7) M ; III: 141-188 (157 ± 15) M ; H: 63-73 (68 ± 3) p. Length of longest setae

on frons: 10-43 (28 ± 9) p, tips incrassate. Head width: 245-316 (285 ± 19) p. Length of stylets:

530-694 (608 ± 55) p\ ultimate rostral segment: 68-83 (76 ± 5) p, rostral tip reaching abdominal

terga I or II in dorsal view through slide-mounted specimens. Head + pronotum fused, total length:

367-439 (399 ± 24) p. THORAX: Meso + metanota fused, total length: 296-388 (347 ± 28) p.

ABDOMEN: Tergum I free, length: 112-163 (138 ± 15) p\ terga II-VII fused, VIII free. Maximum

distal width of flange on siphunculi: 45-55 (50 ± 4) p; siphunculi nearly flush to truncated conical,

protruding to 1.0 x maximal distal width. Ventral abdominal sclerites on segments III-IV subquadrate,

subcircular to subelliptical; length: 50-68 (59 ± 6) p, 1.2-2.Ox diameter of metatibiae. Dorsal (major

+ minor) setae (see Fig. IB) on abdominal terga III-IV: 10-14 (11 ± 1), tips sharp, in 2 irregular

rows, lateral-most minor dorsal seta usually in anterad row; marginal setae 4-6 per segment each side.

Setae on abdominal tergum VIII: 10-14 (11 ± 1), length: 5-43 (23 ± 11) p, tips incrassate to rarely

sharp, in 2 irregular rows. Cauda rounded; caudal protuberance moderately developed to frequently

nearly absent; length of longest caudal setae: 70-103 (86 ± 10) p, tips sharp. LEGS: Length of

metafemora: 500-663 (578 ± 53) p ; metatibiae: 622-900 (755 ± 70) p; longest dorsal setae on central

one-third of metatibiae: 20-30 (24 ± 3) p, 0.1-0.6 x diameter of metatibiae, tips incrassate, approx¬

imately equal or very gradually increasing distally, no setal length dimorphism; longest ventral setae

on metatibiae: 13-28 (23 ± 4) p, tips sharp. Length of metabasitarsus: 93-118 (104 ± 7) p\ meta-

distitarsus: 165-213 (188 ± 13) p. Ratio of metadistitarsus to metabasitarsus averaging 1.81:1, usually

less than 1.9:1, rarely reaching 2.0:1 or slightly more. Pigmentation: Color in life: Gray-green, occa¬

sionally pale yellow throughout. Slide-mounted specimens: Background of body dorsum pale (to 10

percent pigment density), unicolorous. Terga at bases of setae on frons and dorsal (major + minor)

setae on abdomen concolorous with surrounding terga. Thoracic muscle attachment plates pale, in¬

conspicuous to conspicuous. Dorsal muscle attachment plates of abdomen conspicuous, pale, infre¬

quently dusky. Spiracular plates and ventral abdominal sclerites usually light brown, slightly darker

than background of abdominal terga, to pale. Siphunculi concolorous with surrounding terga. Cauda,

anal and subgenital plates concolorous with abdominal terga. Antennal segments V and IV slightly to

moderately dusky over entire segment, to moderately brown distally; III pale; II and I concolorous

with frons. Pro-, meso- and metatibiae usually pale, concolorous, equivalent to body dorsum; fre¬

quently tibiae subtly dusky at distal tip, rarely entire tibiae moderately dusky, slightly darker than

body dorsum. Distitarsi usually subtly dusky distally to moderate brown, varying with antennae,

infrequently entirely dusky with tibiae.

Ultimate Stadium Nymphs of Viviparous Apterae.— Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites. Mesonotum with 2 sclerotized plates extending from muscle attachment sites to

engulf neighboring setal bases; plates usually vague, faintly pigmented, diameter approximately equal¬

ing eye length.

Oviparae. -Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae ex¬

cept abdominal terga II-VI fused, lightly to moderately sclerotic, including pleural areas, but VII and

VII free; dorsal demarcations of anterad terga not evident; siphunculi usually incorporated into sclerotic

dorsum, to free; dorsal abdominal muscle attachment plates pale, unicolorous, except those between

terga VI-VII darker. Pseudorhinaria on metatibiae irregular, difficult to distinguish, 7-11.

Viviparous Alatae, Males, Fundatrices.— Unknown.

Diagnosis. —Essigella (A.) kirki can easily be confused with other pale individ¬

uals of Essigella. It can be separated from all Essigella, except E. (A.) kathleenae,

E. (L.) eastopi, E. ( L .) fusca, E. (L.) hillerislambersi, and odd specimens of E.

(E.) wilsoni and E. (E.) knowltoni braggi, by having 10 or more dorsal (major +

minor) setae on abdominal terga III-IV, in two rows, with the lateral-most minor

dorsal seta in the anterad row (e.g., Fig. IB). Essigella (A) kirki lacks the very

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Figure 2. Distribution of E. (A.) kirki [dots (JTS samples)], superimposed over the ranges of its

hosts, Pinus flexilis [lighter shading] and Pinus strobiformis [darker shading (AZ, NM and south)].

elongate metadistitarsus of E. (A.) kathleenae, having a metadistitarsus to meta-

basitarsus ratio of usually less than 1.9:1, but rarely to 2.0:1 [mean: 1.8:1 for E.

(A) kirki, 2.05:1 for E. (A.) kathleenae ]. It can be separated from other pale

Essigella, however, by having this ratio at over 1.7:1. Essigella (A.) kirki lacks

the protuberant, exceptionally distad primary rhinarium of E. {E.) wilsoni. It can

be further distinguished from pale E. ( L .) fusca and E. (L.) hillerislambersi, and

some pale E. ( L .) eastopi and E. ( E .) knowltoni braggi by having the longest dorsal

setae on the central part of the mesotibia less than 0.7 x tibial diameter. All

observed E. (E.) knowltoni braggi with 10 or more dorsal (major + minor) setae

on abdominal terga III-IV differ from E. {A.) kirki by having the longest dorsal

metatibial setae in excess of 1.0 x tibial diameter; however, rare, confusing E.

(E.) knowltoni braggi are anticipated, and these could be separated by their broad

1994

SORENSEN: A REVISION OF ESSIGELLA

head on noncompressed slides, and by usually longer setae on the frons [see

descriptions and E. ( E .) knowltoni diagnosis].

Range. —Rocky Mountains, Montana to Arizona and New Mexico; southern

Sierra Nevada (east slope) and White Mountains of California; presumably into

Mexico and Canada with its hosts (Fig. 2).

Hosts. —Pinus flexilis James and P. strobiformis Engelmann; the latter was pre¬

viously considered to be a variety [as P. flexilis var. reflexa Engelmann] of the

former. These pines split the higher elevation niche in the Rocky Mountains, with

P. flexilis in the north, P. strobiformis in the south, and some intergradation at

their contact in northern New Mexico (Critchfield & Little 1966). The only other

Essigella species on these pines is E. (E.) californica, which has secondarily in¬

vaded the niche, opportunistically, and is much less common in it than E. (A.)

kirki.

It is possible that E. (A.) kirki also occurs on P. ayacahuite Ehrenberg in central

Mexico and south, because that pine was formerly considered a variety of P.

strobiformis (as P. ayacahuite var. brachyptera Shaw); P. ayacahuite apparently

continues the P. flexilis to P. strobiformis morphological and geographic cline

(Critchfield & Little 1966), and although discontinuous with the latter, a single

isolated stand in western Jalisco, Mexico (Critchfield & Little 1966: map 9) is

morphologically intermediate with P. strobiformis (Martinez 1948).

Discussion. —Because of previous misinterpretation of meso- and metanotal

fusion in Essigella (see character discussion section), the description given here

for this species is more accurate than that in Sorensen (1988).

Essigella (A.) kirki is a common species that is relatively homogeneous, mor¬

phologically, and always pale, unlike several other Essigella species that can grade

from pale to fully pigmented; in these respects it resembles E. {A.) kathleenae.

Sorensen (1983) determined that it differs from the latter in bivariate plots of

head width, between the lateral rims of the antennal sockets, versus body length,

and of metadistitarsus versus metabasitarsus lengths; it also separates under prin¬

cipal component and discriminant function analyses (Sorensen 1983).

Coded References to This Taxon.—Essigella (A.) kirki has been referred to

previously by: the coding “Sp. K” (Sorensen 1983, 1987a, 1992b) and “HOTT”

(Sorensen 1983), and by the manuscript name E. “hottesi ” in Sorensen (1983).

Etymology and Common Name.— The species was named for my son, Kirk

Hale Sorensen. Common name: Kirk’s limber pine needle aphid.

Material Examined.— ARIZONA. APACHE Co.: Lake Harney Rd (hwy 473), nr McNary, 2440

m, 11 Sep 1978, JTS 78114, P. strobiformis, (apt.). COCHISE Co.: nr Rustler Park, Chiricahua Mts,

2500 m, 16 Sep 1978, JTS 78150, P. strobiformis, (apt.). CALIFORNIA. INYO Co.: Lake Sabrina,

nr Bishop, 2750 m, 1 Aug 1977, JTS 77H2, P. flexilis, (apt.); Onion Valley Cmpgd, 24 km W of

Independence, 2770 m, 4 Aug 1978, JTS 78H13, P. flexilis, (apt.). COLORADO. SAN JUAN Co.: 20

km N of Purgatory, 3020 m, 8 Aug 1978, JTS 78H47, P. flexilis, (apt.). MONTANA. CARBON Co.:

Red Lodge, 1770 m, 20 Aug 1978, JTS 78H115, P. flexilis, (apt.). NEVADA. WHITE PINE Co.:

Wheeler Peak, 3140 m, 26 Aug 1978, JTS 78H147, P. flexilis, (apt., ovip.). NEW MEXICO. OTERO

Co.: 3 km W of Cloudcroft on hwy 82, 2560 m, 13 Sep 1978, JTS 78122, P. strobiformis, (apt., ovip.).

SANTA FE Co.: (type series) 30 km NE of Santa Fe on hwy 475, 3100 m, 10 Aug 1978, JTS 78H55,

P. flexilis, (apt.). SIERRA Co.: Emory Pass on hwy 90, W of Kingston, 2470 m, 14 Sep 1978, JTS

78134, P. strobiformis, (apt.). UTAH. DUCHESNE Co.: 19 km NE of Castle Gate on hwy 33, 2770

m, 25 Aug 1978, JTS 78H144, P. flexilis, (apt.). WYOMING. ALBANY Co.: 5 km SW of Woods

Landing on hwy 230, 2560 m, 15 Aug 1978, JTS 78H92, P. flexilis, (apt.).

THE PAN-PACIFIC ENTOMOLOGIST

Yol. 70(1)

Essigella ( Archeoessigella ) kathleenae Sorensen, 1988

Essigella kathleenae Sorensen, 1988: 115, Pan-Pacif. Entomol., 64: 115-118.

Essigella “ kathleeni ” Sorensen, 1988: 124 (lapsus), Pan-Pacif. Entomol., 64: 124.

Essigella “ kathleenae ” Sorensen, 1983: 67 (unpublished manuscript name) Ph.D.

Thesis, University of California at Berkeley, Berkeley, California. 605 p.

Type Series. — Holotype, vivip. apt.; on slide with 3 paratype vivip. apt., ho-

lotype at upper left (11 o’clock position); data: CALIFORNIA. SAN BERNAR¬

DINO Co.: 3 km S of jet hwy 38 & Jenks Lake Rd, San Bernardino Mts, 2200

m, 16 Sep 1977, J. T. Sorensen (77138), Pinus lambertiana Douglass. Holotype

retained in Sorensen collection, eventually to be deposited in The Natural History

Museum, London. Paratypes (all same data as holotype): 30 vivip. apt. on 7 slides

including holotype slide. Paratype slides deposited: 1 slide in NMNH, Washing¬

ton, D.C.; 1 slide in CNC, Ottawa, Ontario; 8 slides in Sorensen collection.

Viviparous Apterae.—Morphology: Body length: 1.35-2.01 (1.67 ± 0.18) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 85-113 (102 ± 7) p, processus terminalis: 28-43 (40 ±

4) M ; IV: 60-90 (75 ± 9) p\ III: 98-135 (118 + 11) m; H: 55-68 (62 ± 4) p. Length of longest setae

on frons: 8-25 (17 ± 6) p, tips incrassate. Head width: 215-258 (242 ± 11) p. Length of stylets: 428-

653 (581 ± 64) p\ ultimate rostral segment: 55-78 (66 ± 5) p, rostral tip reaching metanotum to

abdominal terga III in dorsal view through slide-mounted specimens. Head + pronotum fused, total

length: 286-377 (334 ± 31) p. THORAX: Meso + metanota fused, total length: 214-306 (280 ±31)

p. ABDOMEN: Tergum I free, length: 93-133 (119 ± 12) p; terga II-VII fused, VIII free. Maximum

distal width of flange on siphunculi: 23-38 (32 ± 4) p\ siphunculi flush to truncated conical, protrusion

to 0.5 x maximum distal width. Ventral abdominal sclerites on segments III-IV subcircular, subquad¬

rate to subelliptical; length: 36-60 (48 ± 8) p, 1.3-2. lx diameter of metatibiae. Dorsal (major +

minor) setae (see Fig. IB) on abdominal terga III-IV: 11-14 (12 ± 1), tips sharp, in 2 irregular rows;

marginal setae 4-5 per segment each side. Setae on abdominal tergum VIII: 7-13 (10 ± 2), length:

5-40 (14 ± 10) p, tips incrassate to sharp, in 2 irregular rows. Cauda rounded; caudal protuberance

moderately developed, to infrequently nearly absent; length of longest caudal setae: 40-93 (61 ± 16)

p, tips sharp. LEGS: Length of metafemora: 316-541 (448 ± 67) p; metatibiae: 428-704 (569 ± 77)

p\ longest dorsal setae on central one-third of metatibiae: 5-23 (13 ± 6) p, 0.1-0.8 x diameter of

metatibiae, tips incrassate; approximately equal or very gradually increasing distally, no setal length

dimorphism; longest ventral setae on metatibiae: 10-25(19 ± 5)^, tips sharp. Length of metabasitarsus:

60-95 (79 ± 10) p\ metadistitarsus: 135-180 (162 ± 12) p. Ratio of metadistitarsus to metabasitarsus

averaging 2.05:1, greater than 1.9:1, and usually greater than 2.0:1. Pigmentation: Color in life: Pale

yellow throughout. Slide-mounted specimens: Background of body dorsum pale (usually to 10, some¬

times to 30, percent pigment density), unicolorous. Terga at bases of setae on frons and dorsal (major

+ minor) setae on abdomen concolorous with surrounding terga. Thoracic muscle attachment plates

and dorsal muscle attachment plates of abdomen, pale, inconspicuous. Spiracular plates and ventral

abdominal sclerites pale. Siphunculi concolorous with surrounding terga. Cauda, anal and subgenital

plates pale, concolorous with abdominal terga, to slightly darker. Antennal segments V and IV pale,

only very subtly darker than body dorsum; III very pale to distal one-third pale as V and IV; II

concolorous with proximal III; I concolorous with frons. Pro-, meso- and metatibiae usually pale,

concolorous with body dorsum, to very subtly darker. Distitarsi entirely pale to subtly dusky on distal

one-third.

Ultimate Stadium Nymphs of Viviparous Apterae. — Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites. Mesonotum with 2 sclerotized plates extending from muscle attachment sites to

engulf neighboring setal bases; plates usually vague, faintly pigmented, diameter approximately equal¬

ing eye length.

1994

SORENSEN: A REVISION OF ESSIGELLA

Oviparae.— Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae, ab¬

dominal terga II-VII fused, lightly to moderately sclerotic, including pleural areas, tergum VIII free;

dorsal demarcations of anterad terga not evident; siphunculi incorporated into sclerotic dorsum; dorsal

abdominal muscle attachment plates pale, unicolorous. Pseudorhinaria on metatibiae irregular, difficult

to distinguish, 5-9.

Viviparous Alatae, Males, Fundatrices.— Unknown.

Diagnosis.—Essigella (A.) kathleenae is consistently pale, and usually can be

identified by the unique, exceptionally long metadistitarsus and short metabasi-

tarsus. The length ratio of the metadistitarsus to metabasitarsus usually exceeds

2.0:1, and only rarely approaches 1.9:1, the upper value for all other Essigella,

except occasional E. (A.) kirki.

Range. —California and southwestern Oregon (Fig. 3).

Hosts. —Pinus lambertiana Douglass; questionable single occurrences on P. jef-

freyi Greville & Balfour, P. sabiniana Douglass and P. monticola Douglass. A

single specimen attributed to P. jejfreyi (77166) is probably a beating tray contam¬

ination from a preceding collection (77164) from P. lambertiana, which occurred

at dusk. A single specimen from P. sabiniana (77G17) is probably also similarly

accidental, following a preceding collection on P. lambertiana (77G16). My col¬

lection from P. monticola (78G7) is a questionable host determination; that col¬

lection is from an isolated, low elevation stand of pines that W. B. Critchfield

(personal communication) believes to be P. monticola, but that I believe is possibly

P. lambertiana on the basis of its ecological, geographic and elevational circum¬

stances [P. monticola replaces P. lambertiana at higher elevations in the Sierra

Nevada, and the P. monticola niche is opportunistically occupied by E. {E.)

californica .]

Discussion.— Because of previous misinterpretation of meso- and metanotal

fusion in Essigella (see character discussion section), the description given here

for this species is more accurate than that in Sorensen (1988).

Essigella (A.) kathleenae is a common, morphologically homogeneous species.

Its elongate metadistitarsus and very shortened metabasitarsus represent a ple-

siomorphy within Essigella ; this is shared with Pseudessigella, which has a much

higher tarsal ratio and differing metatarsal regression. Essigella (A.) kirki nearly

shares the same metatarsal regression with E. (A.) kathleenae, but is displaced

along the regression by its slightly longer metabasitarsus. Essigella {A.) kathleenae

may have no conventional apomorphies beyond those defining the genus; the

confusing polarity for the fused abdominal terga of oviparae, which differs between

E. (A) kathleenae and E. {A.) kirki, is discussed in the character discussion section.

Coded References to This Taxon.—Essigella (A.) kathleenae has been referred

to previously by: the coding “Sp. J” (Sorensen 1983, 1987a, 1992b) and “KATH”

(Sorensen 1983), and by the manuscript name E. “kathleenae ” in Sorensen (1983).

Etymology and Common Name. — The species is named for my wife, Kathleen

Hale Sorensen, who served as my field botanist during this study. Common name:

Kathleen’s sugar pine needle aphid.

Material Examined. — CALIFORNIA. CALAVERAS Co.: 18 km E of Arnold on hwy 4, 1680 m,

17 Jul 1977, JTS 77G45, P. lambertiana, (apt.). DEL NORTE Co.: Panther Flat Cmpgd, Six Rivers

Natl Forest, at Pioneer Rd & hwy 199, E of Gasquet, 4 Jul 1978, JTS 78G7, P. monticola, (apt.). EL

DORADO Co.: Lake Tahoe, Emerald Bay, 1980 m, 16 Jul 1977, JTS 77G30, P. lambertiana, (apt.).

FRESNO Co.: jet of hwy 180 & Sequoia Lake turnoff, nr Pinehurst, 1710 m, 13 Aug 1977, JTS

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Figure 3. Distribution of E. (A.) kathleenae [dots (JTS samples)], superimposed over the range of

its host, Pinus lambertiana [shaded].

77H10, P. lambertiana, (apt.). KERN Co.: Tiger Flat Rd, N of hwy 155, nr Alta Sierra, 1890 m, 20

Sep 1977, JTS 77164, P. lambertiana, (apt.); same but JTS 77166, P. jeffreyi, (apt.). LOS ANGELES

Co.: 3 km SE of Big Pines on hwy 2, E of Blue Ridge Summit, 2200 m, 17 Sep 1977, JTS 77148, P.

lambertiana, (apt., ovip.). MARIPOSA Co.: Yosemite Natl Park, 13 km W of Crane Flat on hwy 120,

2140 m, 1 Aug 1977, JTS 77H6, P. lambertiana, (apt.). MENDOCINO Co.: Fish Rock Rd, 27 km E

of hwy 1, 490 m, 23 Jul 1977, JTS 77G49, P. lambertiana, (apt.). MONTEREY Co.: Cone Peak Rd,

13 km N of jet with Nacimento-Fergusson Rd, Los Pardes Natl Forest, 1310 m, 4 Sep 1977, JTS

77110, P. lambertiana, (apt.). PLACER Co.: 5 km SW of Whitmore on hwy 80, 1430 m, 25 Jun 1977,

JTS 77F2, P. lambertiana, (apt.). PLUMAS Co.: hwy 36, 6 km W of jet with hwy 89, 1460 m, 10 Jul

1977, JTS 77G22, P. lambertiana, (apt.); 8 km E of Chester on hwy 36, 1520 m, 4 Jul 1977, JTS

77G16, P. lambertiana, (apt.). RIVERSIDE Co.: South Ridge Rd, nr Idyllwild, 1770 m, 9 Sep 1977,

JTS 77121, P. lambertiana, (apt.). SAN BERNARDINO Co.: (type series) San Bernardino Mts, 3 km

S of jet of hwy 38 & Jenks Lake Rd, 2200 m, 16 Sep 1977, JTS 77138, P. lambertiana, (apt.); same

but 3 km S of Lake Gregory, 1490 m, 17 Sep 1977, JTS 77145, P. lambertiana, (apt.). SISKIYOU

Co.: Mt Shasta Ski Bowl Rd, 2450 m, 2 Jul 1977, J. T. Sorensen & D. J. Voegtlin, JTS 77G8, P.

lambertiana, (apt.). TEHAMA Co.: Lanes Valley Rd, nr jet with hwy 36, 490 m, 4 Jul 1977, JTS

1994

SORENSEN: A REVISION OF ESSIGELLA

77G17, P. sabiniana, (apt.). TRINITY Co.: East County Line Rd, 5 km S of Buckhom Summit on

hwy 299, W of Tower, 1530 m, 20 Aug 1977, JTS 77H19, P. lambertiana, (apt.). TUOLUMNE Co.:

2 km E of Groveville on hwy 120, 910 m, 30 Jul 1977, JTS 77G62, P. lambertiana, (apt.); same but

JTS 77G63, P. ponderosa, (apt.). VENTURA Co.: Reyes Peak Rd, 10 km E of Pine Mt Summit on

hwy 33, 2200 m, 19 Sep 1977, JTS 77158, P. lambertiana, (apt.). OREGON. JACKSON Co.: 15 km

S of Union Creek on hwy 62, 850 m, 5 Jul 1978, JTS 78G17, P. lambertiana, (apt.).

Essigella ( Lambersella ), NEW SUBGENUS

“Essigella ( Lambersella )” Sorensen, 1983: 73 (unpublished manuscript name)

Ph.D. Thesis, University of California at Berkeley, Berkeley, California. 605 p.

Type Species.—Essigella fusca Gillette & Palmer, 1924, Ann. Entomol. Soc.

Am., 17: 6-9.

Viviparous Apterae.— Morphology: Body not relatively broad. Meso- and metanota fused dorsally;

abdominal tergum I free. Dorsal setae (majors and minors) between muscle attachment plates on

abdominal segments III-IV in 2 (rarely 1) often irregular rows (see Figs. 1C-D); lateral-most dorsal

minor seta on each side anterad (rarely not) of its immediately mesad neighbor. Abdominal terga III-

IV each with 8-12 dorsal (major + minor) and 3-5 (per side) marginal setae; tergum VIII with 8-11,

rarely 12, setae. Longest dorsal seta on central one-third of metatibiae to nearly 4x tibial diameter,

tips incrassate to sharp, sometimes reflexed; these setae sometimes dimorphic in length or with abrupt

length transition, nearly doubling, centrally on the metatibiae. Ventral abdominal sclerites on segments

III-IV reduced (rudimentary), irregular stellate to large, subquadrate to sublinear, often broken into

linearly separated parts. Species means for length ratio of metadistitarsus to metabasitarsus varying

between 1.39:1 to 1.54:1. Pigmentation: Body dorsum variable, pale to dark brown, background

unicolorous or not, often mottled; bases of dorsal setae of abdomen concolorous with surrounding

terga to substantially darker. Tibiae varying from entirely pale to nearly black, but when darkened

mesotibiae at least subtly to usually substantially paler than pro- and metatibiae.

Diagnosis. — See the key to the subgenera of Essigella.

Discussion.—Lambersella is monophyletic and convex (sensu Duncan 1980,

Estabrook 1986), and represents the sister clade of E. (Essigella ). The major

nonhomoplasious, qualitative synapomorphy for this subgenus is its “dark-light-

dark” tibial pigmentation suite for the pro-, meso- and metatibiae, respectively.

Also, unlike any other Essigella, there is also a tendency for the ventral abdominal

sclerites on segments III-IV to often be linear; that trait is problematic, however,

because it is shared by Pseudessigella (e.g., Sorensen 1991: figs. 2b-e). I consider

a length dimorphism of the dorsal setae on the metatibiae [except E. (L.) hilleris-

lambersi ] and the usually faint, to absent, forewing medius of alates [morph

unknown for E. (L.) eastopi ] to be apomorphies that are unique to Lambersella,

but that are not found in, or known from, all its species. Of the Lambersella

species, the phylogenetic analysis (Fig. 13) shows E. ( L .) eastopi to be the least

derived (closest to the ancestral node 3) and E. ( L .) hillerislambersi the most, in

anagenic distance from node 3.

Ecologically, Lambersella has invaded the genetically distinct subsection Pon-

derosae of the diploxylon pines (subgenus Pinus)\ only E. ( L .) eastopi feeds chiefly

on a subsection Sabinianae pine, perhaps reflecting its relatively primitive status

in the subgenus. Sorensen (1983: section 2) analyzed the relationships among the

taxa within this subgenus; see the discussion under E. (L.) eastopi for a summary.

An apparent case of character displacement has occurred under sympatry in

California between E. (L.) fusca voegtlini and E. ( L .) hillerislambersi, with respect

to bivariant regressions of the length of dorsal setae on the metatibia versus

metatibial length (unpublished data); see discussion of E. (L.) fusca voegtlini. This

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

suggests that Lambersella species compete for their pine hosts as resources, as

apparently do species in the E. ( E .) knowltoni group of E. (Essigella ) (Sorensen

1992a), where a similar form of character displacement also occurs.

Coded References to This Taxon. — Sorensen (1983) referred to this taxon under

the manuscript name “ Essigella (Lambersella) Sorensen (1987a) referred to the

assemblage that comprises this taxon as group “II” or, with reference to its sub¬

components, as “O-N-M-L” [or entire permutations therefore]; in Sorensen (1992b),

the latter refers to it.

Etymology. — The subgenus is named for Dirk Hille Ris Lambers, who pointed

out the tibial pigmentation synapomorphy.

Material Examined.—Essigella (L.) eastopi, E. ( L .) fusca fusca, E. (L.) fusca voegtlini, E. (L.)

hillerislambersi.

Essigella (Lambersella) eastopi, NEW SPECIES

Essigella “eastopi ” Sorensen, 1983: 76 (unpublished manuscript name) Ph.D.

Thesis, University of California at Berkeley, Berkeley, California. 605 p.

Type Series. — Holotype, vivip. apt.; on slide with 1 paratype vivip. apt., ho-

lotype on top (12 o’clock position); data: CALIFORNIA. SAN DIEGO Co.: 8 km

N of Mt Laguna, hwy SI, 1700 m, 12 Sep 1977, J. T. Sorensen (77132), Pinus

coulteri D. Don. Holotype deposited in The Natural History Museum, London.

Paratypes (all same data as holotype): 17 vivip. apt. on 5 slides including holotype

slide. Paratype slides deposited: 1 slide in NMNH, Washington, D.C.; 1 slide in

CNC, Ottawa, Ontario; 2 slides in Sorensen collection. (The type series represents

smaller, darker specimens with short setae; these are the more distinctive form

of E. (L.) eastopi.)

Viviparous Apterae.— Morphology: Body length: 1.65-1.98 (1.84 ± 0.09) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 105-133 (118 ± 8) g, processus terminalis: 30-40 (34 ±

3) ix- IV: 73-88 (82 ± 5) m; HE 133-183 (146 ± 13) II: 65-73 (69 ± 2) ix. Length of longest setae

on frons: 45-66 (52 ± 8) ix, tips incrassate to sharp. Head width: 270-306 (286 ± 11) ix. Length of

stylets: 714-836 (766 ± 39) ix: ultimate rostral segment: 65-90 (81 + 8) ix, rostral tip reaching abdominal

terga I—III in dorsal view through slide-mounted specimens. Head + pronotum fused, total length:

357-428 (385 ± 21) ix. THORAX: Meso + metanota fused, total length: 316-388 (348 ± 21) g.

ABDOMEN: Tergum I free, length: 133-184 (158 ± 21) terga II-VII fused, VIII free. Maximum

distal width of flange on siphunculi: 33-45 (40 ± 3) siphunculi truncated conical, protrusion 0.2-

0.6 x maximal distal width. Ventral abdominal sclerites on segments III-IV subquadrate, subelliptical

to sublinear; length: 44-59 (52 ± 5) ix, 1.3-2.Ox diameter of metatibiae. Dorsal (major + minor)

setae (see Figs. 1C-D) on abdominal terga III-IV: 8-10 (9 ± 1), tips blunt to sharp, in 2 (rarely 1)

rows with setae in regular positions, lateral-most minor dorsal seta in anterad row (rarely not); marginal

setae 3-4 per segment each side. Setae on abdominal tergum VIII: 8-11 (9 ± 1), length: 45-73 (55 ±

9) ix, tips incrassate to sharp, in 1 or 2 irregular rows. Cauda rounded; caudal protuberance absent to

poorly developed; length of longest caudal setae: 75-103 (91 + 9) ix, tips sharp. LEGS: Length of

metafemora: 490-704 (578 ± 59) m; metatibiae: 612-908 (699 ± 84) ix\ longest dorsal setae on central

one-third of metatibiae: 23-83 (53 ± 17) n, 0.3-2.3 x diameter of metatibiae, tips incrassate to sharp;

length variable, either approximately equal to gradually increasing distally, or abruptly doubling in

length on central tibiae with setal length dimorphism present; longest ventral setae on metatibiae: 23-

43 (34 ± 7) ix, tips sharp. Length of metabasitarsus: 104-128 (115 ± 7) /x; metadistitarsus: 163-195

(177 ± 11) ix. Ratio of metadistitarsus to metabasitarsus less than 1.9:1, mean 1.54:1. Pigmentation:

Color in life: Yellow throughout to body brown with yellow frons, legs and longitudinal stripe on

1994

SORENSEN: A REVISION OF ESSIGELLA

dorsomedial thoracic and abdomen. Dark specimens with tibiae usually yellow, to infrequently pro-

and metatibiae as dark as dorsum, mesotibiae yellow; yellow specimens with tibiae concolorous with

body to pro- and metatibiae brown, mesotibiae yellow. Slide-mounted specimens: Background of body

dorsum variable, unicolorously pale to dark brown with paler frons and longitudinal area on dorso¬

medial terga of thorax and anterad of abdomen; dark pigmentation homogeneous to mottled (to 80

percent pigment density), when latter the pigmentation is density centers around each of the mesal

pair of muscle attachment plates on the abdominal dorsum. Terga at bases of setae on frons and dorsal

(major + minor) setae on abdomen concolorous with surrounding terga, to very subtly darker. Thoracic

muscle attachment plates and dorsal muscle attachment plates of abdomen pale, vaguely conspicuous,

to dark brown, reticulate with well defined borders, conspicuous. Spiracular plates and ventral ab¬

dominal sclerites light to dark brown, conspicuous. Siphunculi concolorous with surrounding terga.

Cauda, anal and subgenital plates concolorous with abdominal terga, to slightly darker. Antennal

segments V dusky; IV usually dusky on distal one-half or central one-third, frequently entirely dusky;

III usually pale, infrequently subtly dusky on distal extreme when IV is entirely dusky; II very pale;

I concolorous with frons. Tibiae variable, usually concolorously pale, despite dorsal pigmentation,

often to moderate brown with pro- and metatibiae darker than mesotibiae; when metatibiae dark,

rarely proximal one-third and ventrodistal tip subtly paler, or rarely pigmentation increasing evenly

distally. Distitarsi dusky on distal one-half to three-quarters, when tibiae pale, to entirely brown with

tibiae.

Ultimate Stadium Nymphs of Viviparous Apterae. — Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distant scleroites. Mesonotum with 2 sclerotized plates extending from muscle attachment sites to

engulf neighboring setal bases; plates usually heavily, to faintly, pigmented, diameter approximately

equaling eye length.

Viviparous Alatae, Oviparae, Males, Fundatrices.— Unknown.

Diagnosis. —Essigella (L.) eastopi consists of pale to dark brown individuals.

Dark specimens usually can be distinguished from other Essigella by having a

dark brown body dorsum with a paler, longitudinal area on the dorsomedial region

of the thoracic and anterad abdominal dorsum. The tibial pigmentation of E. (L .)

eastopi is similar to that of E. (L.) fusca and E. (L.) hillerislambersi, and varies

from all tibiae concolorously pale to a pigmentation suite in which the pro- and

metatibiae are subtly to substantially darker than the mesotibiae; the latter is less

prevalent in those E. ( L .) eastopi with a dark body dorsum. When pale, the three

Lambersella species can be difficult to separate. Some E. ( L .) eastopi with short

dorsal setae on the metatibiae (less than 1.2 x tibial diameter) and E. (L .) fusca

with long setae (greater than 3.0 x tibial diameter) are exclusive. Essigella (L.)

hillerislambersi is larger and can be separated from E. ( L .) eastopi if antennal

segment III exceeds 0.190 mm. Most morphometric characters overlap in these

three species; reliable separation requires application of the discriminant functions

in the key to the viviparous apterae [couplets 20 and 21, in that order].

Pale E. ( L .) eastopi also can be confused with most other pale Essigella. They

differ from E. (E.) californica, E. (E.) hoerneri and E. ( E .) pini by having eight

or more (see Figs. 1C-D), rather than six (Fig. IF), dorsal (major + minor) setae

on abdominal terga III-IV. Essigella (L.) eastopi lacks: the abdominal tergum I

fusion of E. ( E.) essigi\ the protuberant, unusually distad primary rhinarium of

E. (E.) wilsoni; and the exceptionally long metadistitarsus and short metabasi-

tarsus of E. (A.) kathleenae. Essigella (L.) eastopi differs from E. (E.) alyeska by

having three to five, rather than two, marginal setae on abdominal terga III-IV,

and having large invasive, rather than small noninvasive, muscle attachment

plates on the mesonotum of later stadia nymphs of apterae. Pale E. (L.) eastopi

differ from pale E. ( E.) knowltoni by being narrower, with sometimes sharply

THE PAN-PACIFIC ENTOMOLOGIST

Yol. 70(1)

Figure 4. Distribution of: A. E. (L.) eastopi [dots (JTS samples)], superimposed over the range of

its host, Pinus coulteri [shaded]. B. E. ( L .) hillerislambersi [dots (JTS samples), squares (nonJTS

samples)], superimposed over the range of its host, Pinus jeffreyi [shaded].

tipped dorsal metatibial setae that frequently have an abrupt increase in length

on the central part of the metatibiae. Pale E. (L.) eastopi with short dorsal metatib¬

ial setae (less than 0.7 x tibial diameter) can be especially similar to E. (A.) kirki,

but have a metadistitarsus to metabasitarsus ratio of less than 1.70:1.

Range. —Coastal ranges of California, south of San Francisco Bay, to Mexico.

The geographic range of E. ( L .) eastopi is the most restricted of the genus (Fig.

4 A).

Host.—Pinus coulteri D. Don. Essigella ( L .) eastopi, on a subsection Sabinianae

pine, is the only E. (Lambersella ) that does not feed primarily on subsection

Ponderosae pines, although P. coulteri does hybridize with P. jeffreyi of subsection

Ponderosae.

Discussion. —Essigella (L.) eastopi is a relatively common species that is fairly

1994

SORENSEN: A REVISION OF ESSIGELLA

variable in morphology, especially in the length of the dorsal setae on the metatib¬

iae. There are two semi-discrete, but intergrading, pigmentation morphs for its

viviparous apterae. The general darkening of the background of the body dorsum

on the darker morph can be considered a homoplasy with that of E. {.Essigella );

however, that morph’s longitudinal, lightened dorsomedial area on the thorax

and abdomen is an autapomorphy for E. {L .) eastopi.

Essigella ( L .) eastopi is evolutionarily close to E. (L.) fusca, with which it shares

several bivariate morphometric regressions. However, it appears to be morpho¬

logically closest to allopatric, rather than sympatric, populations of that species

(see below). Dark individuals of E. {L .) eastopi generally have shorter setae than

do paler specimens, which can approach E. (L.) fusca in appearance. Bivariant

plotting of the longest dorsal seta on the central part of the metatibiae, versus

metatibial length (unpublished data), suggests that E. {L.) eastopi may be a di¬

minutive of E. {L .) fusca voegtlini, with respect to that derived regression line; it

differs in this respect, however, from allopatric E. (L.) fusca fusca, which has

relatively longer metatibiae. The isozymes and nucleic acids of populations of

species in E. (Lambersella) should be examined, especially in the Tehachapi, San

Gabriel and San Bernardino mountains of southern California; there, one large

collection (D. J. Voegtlin 17; Running Springs, San Bernardino Co., on P. coulteri)

is troublesome and may obscure clear separation of E. {L .) eastopi from E. {L .)

fusca voegtlini.

Sorensen (1983) analyzed the relationships among taxa within E. {Lambersella)

using principal component and discriminant function analyses on 35 morpho¬

metric traits. The principal component analysis (Sorensen 1983: section 2 PCA-

1) showed that E. {L.) eastopi differed from E. (L.) fusca, as a species, in general-

size, as represented as the first vector (which had uniformly high trait loadings

and correlations). It was partially displaced from E. (L.) fusca on that vector,

which gave the greatest separation to E. (L.) hillerislambersi. Essigella (L.) eastopi

differed from sympatric E. (L.) fusca voegtlini on the second principal component

vector, which chiefly involved the length of dorsal setae on the metatibiae; how¬

ever, allopatric E. {L.) fusca fusca was intermediate between those two taxa on

that vector. Essigella (L.) eastopi chiefly occupied the same size-independent

principal component attribute space, defined by vectors 2 and 3 after size removal,

as did sympatric E. (L.) hillerislambersi.

The discriminant function analysis (Sorensen 1983: section 2 DFA) echoed the

findings of the principal component analysis, but with better group resolution and

refined intergroup anagenic distances, as expected. Function 1 showed E. (L.)

eastopi had greatest separation from E. (L.) hillerislambersi, with sympatric E.

{L.) fusca voegtlini intermediate between those two, and allopatric E. (L.) fusca

fusca yet intermediate between E. (L.) eastopi and E. (L.) fusca voegtlini. Dis¬

criminant function 2 showed E. ( L .) fusca voegtlini separated from E. (L.) eastopi,

E. (L.) fusca fusca and E. (L. ) hillerislambersi, the three of which overlapped.

These analyses indicate a form of character displacement occurs among the

three E. {Lambersella) species in California under sympatry (unpublished data).

Coded References to This Taxon.—Essigella {L.) eastopi has been referred to

previously by: the coding “Sp. L” (Sorensen 1983 [but not section 2], 1987a,

1992b), “group B” (Sorensen 1983: section 2) and “EAST” (Sorensen 1983); and

by the manuscript name E. “ eastopi ” in Sorensen (1983).

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Etymology and Common Name.— The species is named for the aphidologist

V. F. Eastop, who introduced me to the use and interpretation of bivariate plotting

in aphid taxonomy. Common name: Eastop’s Coulter pine needle aphid.

Material Examined. —CALIFORNIA. LOS ANGELES Co.: hwy 2, 7 km NE of jet with Mt Wilson

Rd, San Gabriel Mts, 1530 m, 18 Sep 1977, JTS 77151, P. coulteri, (apt.). MONTEREY Co.: Cone

Peak Rd, 2 km N of jet with Nacimento-Fergusson Rd, Los Padres Natl Forest, 910 m, 4 Sep 1977,

JTS 7719, P. coulteri, (apt.). ORANGE Co.: above Santiago Peak Rd, 10 km N of jet with hwy 74,

Cleveland Natl Forest, 1220 m, 10 Sep 1977, JTS 77122, P. coulteri, (apt.). RIVERSIDE Co.: Keen

Camp Summit on hwy 74, 3 km N of Mountain Center, San Bernardino Natl Forest, 1500 m, 9 Sep

1977, JTS 77120, P. coulteri, (apt.). SAN BERNARDINO Co.: “view” Picnic Area on hwy 18, W of

Rimforest, San Bernardino Natl Forest, 1620 m, 17 Sep 1977, JTS 77144, P. coulteri, (apt.); 7 km W

of Barton Flat on hwy 38, 1950 m, 16 Sep 1977, JTS 77136, P. coulteri, (apt.). SAN DIEGO Co.: 5

km S of Julian, Harrison Springs Rd, 1460 m, 12 Sep 1977, JTS 77129, P. coulteri, (apt.); (type series)

8 km N of Mt Laguna on hwy SI, 1700 m, 12 Sep 1977, JTS 77132, P. coulteri, (apt.); Mt Palomar

Rd (S6), 3 km S of Mt Palomar, 1530 m, 11 Sep 1977, JTS 77127, P. coulteri, (apt.). SAN LUIS

OBISPO Co.: Cuesto Ridge Botanical Area, nr La Cuesta Summit on hwy 101, N of San Luis Obispo,

730 m, 5 Sep 1977, JTS 77114, P. coulteri, (apt.).

Essigella ( Lambersella ) fusca fusca Gillette & Palmer 1924,

NEW STATUS

Essigella fusca Gillette & Palmer, 1924: 6, Ann. Entomol. Soc. Am., 17: 6-9.

Essigella agilis Hottes, 1957: 71, Proc. Biol. Soc. Wash., 70: 71-73. NEW SYN¬

ONYM.

Essigella palmerae Hottes, 1957: 96, Proc. Biol. Soc. Wash., 70: 96-98. NEW

SYNONYM.

Primary Types. — Lectotype, vivip. apt., on slide alone; slide data: “Essigella

fusca, apt. viv., Holotype, C. P. Gillette & M. A. Palmer, Mt’d. in Damar in

xylene/U.S. Nat. Mus., No. 41953/On Pinus ponderosa var. scopulorum, Rocky

Mt. Nat. Park (Grags Hill [sic], near Bald Pate Inn) Colo., 7-18-23, Coll. M. A.

Palmer, Colo. Agr. Exp. Ac. No. 3422/[on back] lectotype, J. T. Sorensen, 1982.”

Lectotype deposited in the U.S. National Museum of Natural History, Washing¬

ton, D.C.

There is a problem regarding type designation; Hottes (1957: 88) confusingly

mentions both a lectotype and holotype for this species. A slide marked “holotype”

exists. In the original description, Gillette & Palmer (1924: 6-9) do not designate

a primary type, but later (Gillette & Palmer 1931: 840) state “Types in the U.S.

Nat. Mus., Cat. No. 41953; Paratypes in collection of Colo. Agr. Exp. Sta.” Palmer

(1952: 15) under the heading “Type” also lists that number. In addition, 2 slides

(alio- and morphotypes) bear the number, precluding identification of any indi¬

vidual as lectotype, based on the number alone. Because I cannot tell from Hottes’

publication (1957) that he clearly was designating a lectotype, I presently designate

the “holotype” specimen as lectotype, following Hottes’ mention of it. I have

added the lectotype label listed above to the back of that slide. Unfortunately,

the specimen lacks metalegs and is obscured by debris, but it is recognizable as

E. ( L .) fusca.

Viviparous Apterae.—Morphology: Body length: 1.79-2.39 (2.09 ± 0.18) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

1994

SORENSEN: A REVISION OF ESSIGELLA

protuberant. Length of antennal segment V: 118-145 (130 ± 7) ju, processus terminalis: 30-48 (37 ±

4) ix\ IV: 73-100 (88 ± 8) n; III: 135-180 (159 ± 12) /u,; II: 65-95 (76 ± 7) n. Length of longest setae

on frons: 35-80 (58 ± 11) tips incrassate to sharp. Head width: 245-316 (293 ± 17) ji. Length of

stylets: 602-867 (756 ± 62) ultimate rostral segment: 78-98 (90 ± 5) rostral tip reaching abdominal

terga I—II, infrequently III, in dorsal view through slide-mounted specimens. Head + pronotum fused,

total length: 383-479 (424 ± 25) p. THORAX: Meso + metanota fused, total length: 326-459 (400

± 31) ii. ABDOMEN: Tergum I free, length: 138-184 (162 ± 14) p; terga II—VII fused, VIII free.

Maximum distal width of flange on siphunculi: 38-50 (45 ± 3) p\ siphunculi truncated conical,

protrusion 0.2-0.6 x maximum distal width. Ventral abdominal sclerites on segments III-IV subquad¬

rate, subelliptical to sublinear, often centrally constricted; length: 48-90 (73 ± 10) p, 1.2-2.6 x diameter

of metatibiae. Dorsal (major + minor) setae (see Figs. 1C-D) on abdominal terga III-IV: 8-12 (11 ±

1), tips sharp, in 2 (rarely 1) rows with setae in regular position, lateral-most minor dorsal seta in

anterad row; marginal setae 3-5, usually 4 per segment each side. Setae on abdominal tergum VIII:

8-11 (10 ± 1), length: 40-80 (64 ± 9) p, tips incrassate to sharp, in 1-2 rows. Cauda broadly rounded;

caudal protuberance absent to poorly developed; length of longest caudal setae: 83-128 (102 ± 13)

P, tips sharp. LEGS: Length of metafemora: 581-898 (762 ± 95) p\ metatibiae: 755-1132 (971 ±

104) p\ longest dorsal setae on central one-third of metatibiae: 50 (rarely 15)—120 (76 ± 18) p, 0.5-

3.6, usually 1.2-2.8,x diameter of metatibiae, tips usually incrassate to blunt, occasionally sharp;

length variable, either approximately equal along tibiae, gradually increasing distally, or abruptly

doubling in length on central tibiae with setal length dimorphism present; longest ventral setae on

metatibiae: 29-68 (41 ± 9) p, tips sharp. Length of metabasitarsus: 130-170 (148 ± 12) /u; meta-

distitarsus: 170-233 (205 ± 16) p. Ratio of metadistitarsus to metabasitarsus less than 1.9:1, mean

1.39:1. Pigmentation: Color in life: Head and thorax yellow-brown, abdomen green, pro- and meta¬

tibiae light to dark brown with mesotibiae yellow-brown, dorsal spots brown; or frequently green-

yellow to straw yellow, rarely gray throughout. Slide-mounted specimens: Background of body dorsum

pale to moderate brown, often mottled, rarely dark brown (usually to 30, rarely to 80, percent pigment

density). Terga at bases of setae on frons and dorsal (major + minor) setae on abdomen subtly to

substantially darker than surrounding terga. Thoracic muscle attachment plates and dorsal muscle

attachment plates of abdomen varying from moderate to dark brown, conspicuous, often reticulate,

sometimes with surrounding tergum more heavily mottled than elsewhere, to pale, inconspicuous.

Spiracular plates and ventral abdominal sclerites usually moderate to dark brown, conspicuous, to

pale, inconspicuous. Siphunculi concolorous with surrounding terga. Cauda, anal and subgenital plates

concolorous with abdominal terga, to slightly darker. Antennal segments V and IV moderate to dark

brown, usually concolorous, but frequently paler proximally, infrequently also paler distally; III usually

moderate to dark brown on distal one-third, rarely one-half, remainder pale, often entirely pale; II

usually subtly darker than proximal III, seldom conspicuously darker, rarely concolorous with proximal

III; I usually concolorous with frons, to conspicuously darker. Tibiae variable, usually pro- and

metatibiae evenly light to dark brown with mesotibiae substantially paler, sometimes dark pro- and

metatibiae paler on proximal and distal tips to one-fourth; commonly all tibiae concolorously pale

when body dorsum pale. Distitarsi usually evenly light to dark brown with pro- and metatibiae, to

dusky with paler proximal tip when tibiae pale.

Ultimate Stadium Nymphs of Viviparous Apterae.— Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites. Mesonotum with 2 sclerotized plates extending from muscle attachment sites to

engulf neighboring setal bases; plates usually distinct, moderately to darkly pigmented, diameter

approximately equaling eye length.

Viviparous Alatae. - Slide-mounted specimens: Nonmorphometrics as described for viviparous ap¬

terae except lacking body dorsum pigmentation suite; abdominal terga normally membranous, dorsal

(major + minor) setae between muscle attachment plates frequently arising from distinct scleroites;

antennal segments often as dark as tibiae, except proximal one-fifth of III pale. Antennal segment III

with 0-5, IV with 0-1, secondary rhinaria. Epicranial suture absent. Forewing medius with single

furcation arising on proximad one-third of vein; cubital base usually arising distad, infrequently

proximad, on subcosta with distance between anal and cubital bases on subcosta usually relatively

large, ca. 30-40 percent or more of anal vein length; usually medius, sometimes cubitus and anal veins

faint, vague to absent. Abdominal terga frequently with irregular sclerites that engulf or join muscle

attachment plates and dorsal (major + minor) setal bases or scleroites.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Oviparae.— Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae ex¬

cept abdominal terga II-VI fused, lightly to moderately sclerotic, including pleural areas, but VII and

VIII free; dorsal demarcations of anterad terga rarely evident; siphunculi usually incorporated into

sclerotic dorsum, to free; dorsal abdominal muscle attachment plates unicolorous. Pseudorhinaria on

metatibiae irregular, 9-27.

Males. — Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae except

body slightly smaller, with slightly longer antennae and tibiae; dorsal demarcations of abdominal terga

evident. Antennal segment III with 13-15, IV with 8-10, secondary rhinaria.

Fundatrices. — Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae

except siphunculi absent; longest dorsal setae on central part of metatibiae 0.8-1. Ox tibial diameter.

Diagnosis. — Pigmented Essigella (X.) fusca can be distinguished from all Es-

sigella, except E. (L.) hillerislambersi and E. (X.) eastopi, by the tibial pigmentation

suite in which the pro- and metatibiae are often substantially darker than the

mesotibiae. Essigella (X.) fusca lack the completely developed pigmentation for

the body dorsum shown by some E. ( L .) eastopi, but cannot be separated reliably

from E. ( L .) hillerislambersi by pigmentation. Pale E. (X.) fusca, E. (X.) eastopi

and E. (X.) hillerislambersi can be separated from other pale Essigella by the

diagnostics given for pale E. (X.) eastopi. Pale E. ( L .) fusca have longer dorsal

setae on the metatibiae (greater than 1.2 x tibial diameter) than some E. ( L .)

eastopi, and a shorter antennal segment III than E. (X.) hillerislambersi ; but these

differences are indiscrete. Reliable separation of these Lambersella species requires

application of the discriminant functions in the key to the viviparous apterae

[couplets 20 and 21, in that order].

As subspecies, E. (X.) fusca fusca and E. (X.) fusca voegtlini are morphologically

indiscrete, with clinal univariate characters; their separation is locality dependent,

but they can be classified using the discriminant function in the key to the vivip¬

arous apterae [couplet 22]. In Essigella (X.) fusca fusca, the metatibiae and an¬

tennal segment V are generally longer, and the dorsal setae on the metatibiae are

generally shorter, than in E. (X.) fusca voegtlini.

Synonyms. —Essigella agilis Hottes, NEW SYNONYM: holotype, vivip. apt.,

on slide with 4 other specimens, holotype shown by arrow (7-8 o’clock position);

data: COLORADO. MESA Co.: Glade Park, 26 Jun 1956, F. C. Hottes, Pinus

ponderosa Lawson. Essigella agilis holotype deposited in NMNH.

Essigella palmerae Hottes, NEW SYNONYM: holotype, vivip. alat., on slide

with morphotype vivip. apt.; data: ARIZONA. PIMA Co.: Summerhaven, 13 Jun

1954, F. C. Hottes, Pinus ponderosa. Essigella palmerae holotype deposited in

NMNH.

Range.— Southern British Columbia, south: (in the east) through the Rocky

Mountains to Arizona, New Mexico and into Mexico; (in the west) to northern

and eastern Oregon, but not California or southwestern Oregon (Fig. 5). [For

species, see E. (X.) f. voegtlini also.]

Hosts. — Subsection Ponderosae pines, principally Pinus ponderosa Lawson, but

also P. ponderosa var. arizonica Engelmann, P. engelmannii Carriere, and P.

leiophylla Schiede & Deppe (latter, subsection Leiophyllae). Assuming the iden¬

tification is correct, a reputed collection from Callitris drummondii Betham &

Hooker f. ex F. Mueller (Cupressaceae), listed in Blackman & Eastop (in press)

as “BMNH colln, leg. H. G. Walker” [R. L. Blackman, personal communication],

and in Walker et al. (1978: 588) under that host as “31/1/71 Moderate (VFE),”

is undoubtedly from a nonresident host in one of Walker’s many Los Angeles

1994

SORENSEN: A REVISION OF ESSIGELLA

Arboretum samples; most identifications of Essigella to species that are listed in

Walker et al. (1978) are questionable, because only Hottes’ (1957) key was avail¬

able at the time. [For species, see E. (L.) f voegtlini also.]

Discussion.—Essigella (L.) fusca is a common and morphologically variable

species. Sorensen (1983) analyzed the E. (Lambersella) species; see the discussion

of E. (L.) eastopi for a brief summary. That study also analyzed E. ( L .) fusca

itself, after breaking it further into geographic subunits for other principal com¬

ponent analyses (Sorensen 1983: section 2 PCA-2, PCA-3). Within E. (L.) fusca,

general-size variance (Sorensen 1983: section 2 PCA-2, vector 1) dominated any

difference among populations. There was, however, a general east-west gradient

(Sorensen 1983: section 2 PCA-2, vector 2) with longer dorsal setae on the metatib¬

iae, and shorter metatibiae occurring in the west [E. ( L.) f voegtlini ], and the

opposite combination in the more eastern portions of the range [E. (L.) f. fusca].

The next most dominant vector (Sorensen 1983: section 2 PCA-2, vector 3) in

that analysis suggested a very rough north-south morphocline among non-

Californian populations [E. (L .) f fusca], which the Californian material [E. (L .)

f voegtlini] spanned.

When material from California was omitted from those analyses to improve

resolution further, general-size variance (Sorensen 1983: section 2 PCA-3, vector

1) still dominated interpopulational differences among the nonCalifomian pop¬

ulations. However, subordinate to that, nonCalifomian populations [E. ( L .) f

fusca] showed a general north-south gradient (Sorensen 1983: section 2 PCA-3,

vector 2) that involved the length of dorsal setae on the metatibiae and lateral

setae on the body, plus the number of dorsal (major + minor) setae on the

abdomen; this vector, in the absence of interference from E. ( L .) f voegtlini,

oriented to, and improved the resolution of, the variance revealed in the second

vector of the previous analysis (Sorensen 1983: section 2 PCA-2, vector 3). The

third vector (Sorensen 1983: section 2 PCA-3, vector 3) for the nonCalifomian

populations showed mostly intrapopulational variance.

With respect to qualitative traits, E. (L.) fusca fusca populations from Arizona

and New Mexico frequently are slightly paler, with slightly darker metatibiae that

sometimes show both their distal and proximal ends to be paler. This southwestern

material, however, is not considered sufficiently distinct to warrant recognition

with subspecific status on the basis of either quantitative or qualitative traits.

Coded References to This Taxon.—Essigella (L.) fusca fusca has been referred

to previously by: the coding “Sp. M” (Sorensen 1983 [but not section 2], 1987a,

1992b), “group D” (Sorensen 1983: section 2) and “FUSC” (Sorensen 1983); and

by the name E. fusca fusca in Sorensen (1983).

Etymology and Common Name.—“Fusca,” from the Latin “ fuscus ,” meaning

“dusky,” “dark” or “swarthy” (Brown 1978); apparently with reference to “. . .

having dorsum of abdomen dark in color in apterous virgogenia” (Gillette &

Palmer 1924: 8). Common name: the dusky ponderosa pine needle aphid; although

Palmer (1952:14) refers to this species as “The Brown and Green Pine needle

Aphid,” the common name indicated here is more appropriate and less confusing

because other Essigella are brown and green.

Material Examined. — [E. (L.) fusca fusca only :] ARIZONA. APACHE Co.: 10 km N of Lupton

on hwy 12 (= 166), 2070 m, 11 Sep 1978, JTS 78118, P. ponderosa, (apt.). COCHISE Co.: nr Rustler

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Figure 5. Distribution of E. (L.) fusca fusca [black dots (JTS samples), black squares (nonJTS

samples)] and E. ( L.) fusca voegtlini [white triangles (JTS samples), white squares (nonJTS samples)],

superimposed over the range of its principal host, Pinus ponderosa [shaded].

Park, Chiricahua Mts, 2500 m, 16 Sep 1978, JTS 78147, P. ponderosa, (apt.). COCONINO Co.: 9 km

W of Williams on hwy 66, 2070 m, 9 Sep 1978, JTS 7815, P. ponderosa, (apt.). GILA Co.: Pine, 17

May 1978, C. F. & C. S. Smith, CFS 78-31, Pinus sp., (apt.). GRAHAM Co.: SW of Stafford on hwy

366, 1830 m, 15 Sep 1978, JTS 78136, P. leiophylla, (apt.); same but 1980 m, JTS 78137, P. ponderosa

var. arizonica, (apt.). NAVAJO Co.: Mogollon Rim Rd, 8 km SW of Showlow, 2070 m, 10 Sep 1978,

JTS 78113, P. ponderosa, (apt.). PIMA Co./Summerhaven, 13 Jun 1954, F. C. Hottes, (alat.). COUNTY

UNCERTAIN: Sitgreaves Natl Forest, 18 Jun 1969, D. T. Jennings, P. ponderosa, (alat.). COLORADO.

ARCHULETA Co.: 25 km W of Pagosa Springs on hwy 160, 2140 m, 8 Aug 1978, JTS 78H50, P.

ponderosa, (apt.). GUNNISON Co.: 16 km NW of Kebler Pass, 2440 m, 13 Aug 1978, JTS 78H75,

P. ponderosa, (apt.). LARIMER Co.: (lectotype) Bald Pate Inn, nr Craig’s Hill, Rocky Mt Natl Park,

12 Jul 1923, M. A. Palmer, CAES 3420, P. ponderosa, (apt.); (paratype) Craigs, Estes Park, 27 Jul

1923, M. A. Palmer, CAES 3430, P. ponderosa, (alat.); (type) Craigs, nr twin Sisters Mt, 27 Jul 1923,

M. A. Palmer, CAES 3430/USNM 41953, P. ponderosa, (alat.); Estes Park, 1 Sep 1922, F. C. Hottes,

CAES 3312/USNM 41953, P. ponderosa, (ovip., male); same but 24 Jul 1921, C. P. Gillette, CAES

2804, (apt.). MESA Co.: Glade Park, 26 Jun 1956, F. C. Hottes, P. ponderosa, (apt.); Carson Hole,

3/8 Aug 1956, (apt.). SAN MIGUEL Co.: 6 km NE of Placerville on hwy 62, 2320 m, 7 Aug 1978,

1994

SORENSEN: A REVISION OF ESSIGELLA

JTS 78H43, P. ponderosa, (apt.). IDAHO. IDAHO Co.: Deep Creek, nr Old Warrior’s Face, Bitteroot

Natl Forest, 16 Aug 1979, D. J. Voegtlin, DJV 691, P. ponderosa, (apt.). VALLEY Co.: McCall, 23

Sep 1956, M. J. Forsell, P. ponderosa, (apt., alat., ovip., male). MONTANA. MISSOULA Co.: Big

Larch Cmpgd, Seeley Lake, Lola Natl Forest, NE of Missoula, 20 Aug 1979, D. J. Voegtlin, DJV 713,

P. ponderosa, (apt.). NEVADA. WHITE PINE Co.: Wheeler Peak, 2750 m, 26 Aug 1978, JTS 78H153,

P. ponderosa, (apt.). NEW MEXICO. BERNALILLO Co.: 2 km NW of San Antinito on hwy 44, 2290

m, 12 Sep 1978, JTS 78120, P. ponderosa, (apt.). OTERO Co.: Cloudcroft, hwy 82, 2710 m, 13 Sep

1978, JTS 78125, P. ponderosa, (apt.). SANTA FE Co.: 20 km NE of Santa Fe on hwy 475, 2680 m,

10 Aug 1978, JTS 78H59, P. ponderosa, (apt.). SIERRA Co.: 3 km W of Kingston on hwy 90, 2140

m, 14 Sep 1978, JTS 78132, P. ponderosa, (apt., alat.). COUNTY UNCERTAIN: Gila Natl Forest, 19

Jul 1965, H. G. Kinzer, P. ponderosa, (alat.); same but 1 Nov 1967, (apt.). OREGON. BAKER Co.:

11 km W of Unity on hwy 26, 20 Jul 1978, JTS 78G112, P. ponderosa, (alat.). HARNEY Co.: 20 km

N of Bums on hwy 395, 20 Jul 1978, JTS 78G117, P. ponderosa, (apt.). SOUTH DAKOTA. LAW¬

RENCE Co.: 20 km S of Deadwood on hwy 385, 1650 m, 18 Aug 1978, JTS 78H98, P. ponderosa,

(apt.). UTAH. DAGGETT Co.: 21 km S of Manila on hwy 44, 2350 m, 24 Aug 1978, JTS 78H135,

P. ponderosa, (apt.). KANE Co.: 50 km SE of Cedar City on hwy 14, 2560 m, 5 Aug 1978, JTS 78H28,

P. ponderosa, (apt.). WYOMING. ALBANY Co.: hwy 287, 2 km N of state border, 15 Aug 1978, JTS

78H93, P. ponderosa, (apt.). CROOK Co.: 6 km W of Devil’s Tower Jet on hwy 14, 1100 m, 19 Aug

1978, JTS 78H104, P. ponderosa, (apt.). CANADA. BRITISH COLUMBIA: Fairmont Hotsprings,

hwy 93, 17 Jul 1978, JTS 78G91, P. ponderosa, (apt.). MEXICO. PUEBLA: Puebla, km 43 Corn

Fed., 11 Jun 1983, A. L. Munuz, 267, Pinus sp., (apt.). STATE UNCERTAIN: Sierra Largo, at El

Passo, 12 Jun 1966, Eads & Rood, Pinus sp., (apt.).

Essigella (Lambersella) fusca voegtlini, NEW SUBSPECIES

Essigella “ fusca voegtlinr Sorensen, 1983: 89 (unpublished manuscript name)

Ph.D. Thesis, University of California at Berkeley, Berkeley, California. 605 p.

Type Series. — Holotype, vivip. apt., on slide with 2 paratype vivip. apt., the

holotype is only complete specimen on the slide, at top (1 o’clock position); data:

CALIFORNIA. FRESNO Co.: jet hwys 180 & 245, 1620 m, 13 Aug 1977, J. T.

Sorensen (77H9), Pinus ponderosa. Holotype deposited in The Natural History

Museum, London. Paratypes (all same data as holotype): 18 vivip. apt., on 5

slides including holotype slide. Paratype slides deposited: 1 slide in NMNH,

Washington, D.C.; 1 slide in CNC, Ottawa, Ontario; 2 slides in Sorensen collec¬

tion.

Viviparous Apterae.— Morphology: As E. (L.) fusca fusca, except as follows: Body length: 1.88-2.21

(2.04 ± 0.09) mm. HEAD: Length of antennal segment V: 105-135 (121 ± 8) p, processus terminalis:

30-40 (36 ± 3) m; IV: 70-100 (85 ± 7) p\ III: 128-178 (147 ± 14) p; II: 65-85 (73 ± 5) p. Length of

longest setae on frons: 44-88 (59 ± 12) p. Head width: 275-311 (289 ± 10) p. Length of stylets: 551—

857 (732 ± 66) p; ultimate rostral segment: 84-95 (89 ± 3) p. Total length of fused head + pronotum:

377-449 (419 ± 16) p. THORAX: Total length of fused meso + metanota: 347-428 (389 ± 19) p.

ABDOMEN: Tergum I length: 138-179 (157 ± 10) p. Maximum distal width of flange on siphunculi:

30-48 (39 ± 5) p. Ventral abdominal sclerite length: 44-80 (69 ± 9) p. Dorsal (major + minor) setae

(see Figs. 1C-D) on abdominal terga III-IV: 8-12 (10 ± 1); marginal setae 4-5 per segment each side.

Setae on abdominal tergum VIII: 8-10 (8 ± 1), length: 45-100 (69 ± 14) p. Length of longest caudal

setae: 80-120 (98 ± 9) p. LEGS: Length of metafemora: 612-831 (732 ± 62) p\ metatibiae: 806-1061

(941 ± 75) p\ longest dorsal setae on central one-third of metatibiae: 58-135 (103 ± 19) p\ longest

ventral setae on metatibiae: 38-83 (52 ± 11) p. Length of metabasitarsus: 128-155 (141 ± 9) p\

metadistitarsus: 173-223 (198 ± 11) p. Mean ratio of metadistitarsus to metabasitarsus: 1.40:1.

Pigmentation: As E. (L.) fusca fusca.

Diagnosis.—See the E. (L.) fusca fusca diagnosis, and couplet 22 in the key to

the viviparous apterae.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Range.— California, southwestern Oregon, extreme western Nevada (Fig. 5).

[For species, see E. ( L .) f fusca also.]

Hosts. — Subsection Ponderosae pines, principally Pinus ponderosa Lawson, but

also P. jeffreyi Greville & Balfour and P. coulteri D. Don (latter, subsection

Sabinianae); single collections from P. sabiniana Douglass (77F15), P. monophylla

Torrey & Fremont (77H3), P. contorta murrayana Greville & Balfour (R. Luck

sample) and P. quadrifolia Parlatore (77119) are probably not resident. [For spe¬

cies, see E. ( L .) f. fusca also.]

Discussion. —Essigella (L.) fusca voegtlini, although a gradient subspecies [see

discussion under E. ( L .) f. fusca], is named to recognize the morphometric prob¬

lems of E. (L.) fusca in sympatry with E. (L.) eastopi, and especially E. (L.)

hillerislambersi. Essigella (.L.)f. voegtlini [and E. (L.) f. fusca to a very much lesser

extent] shows a common dimorphism of length for the dorsal setae on the meta¬

tibiae. The dimorphism is evident in either of two forms: (a) on a given individual,

as an abrupt transition from shorter to longer setae along the central portion

of the dorsum of the metatibia; or (b) among various individuals in, or among,

populations as the length of the longest setae on the central portion of the dorsum

of the metatibia.

This dimorphism causes a gap along a regression line of length of these setae

when plotted against metatibial length (Sorensen 1983). Interestingly, the length

of the dorsal setae of the metatibiae on E. ( L.) hillerislambersi correspond to this

gap, indicating a character displacement in sympatry. These setal lengths do not

appear to be influenced by host on E. ( L.) f voegtlini.

Coded References to This Taxon. —Essigella (L.)fusca voegtlinih.?iS been referred

to previously by: the coding “Sp. N” (Sorensen 1983 [but not section 2], 1987a,

1992b), “group C” (Sorensen 1983: section 2) and “VOEG” (Sorensen 1983); and

by the manuscript name E. ‘ fusca voegtlini ” in Sorensen (1983).

Etymology and Common Name.— The California subspecies is named for

aphidologist D. J. Voegtlin, and his ever-present beard. Common name: Voegtlin’s

dusky ponderosa pine needle aphid.

Material Examined. — [E. (L.) fusca voegtlini only :] CALIFORNIA. BUTTE Co.: Feather River

Cyn, 5 km NE of jet of hwy 70 & Cherokee Rd, 26 Jun 1977, JTS 77F15, P. sabiniana, (apt.).

CALAVERAS Co.: 18 km E of Arnold on hwy 4, 1680 m, 17 Jul 1977, JTS 77G46, P. ponderosa,

(apt.); 2 km NE of Murphys on hwy 4, 670 m, 17 Jul 1977, JTS 77G47, P. ponderosa, (apt.). EL

DORADO Co.: Georgetown, 29 May 1977, J. T. Sorensen, P. ponderosa, (apt.). FRESNO Co.: (type

species) jet of hwys 180 & 245, 1620 m, 13 Aug 1977, JTS 77H9, P. ponderosa, (apt.). INYO Co.: jet

of Lake Sabrina Rd & Southern Calif. Edison Plant 2 Rd, nr Bishop, 2130 m, 1 Aug 1977, JTS 77H3,

P. monophylla, (apt.). KERN Co.: Tehachapi Mtn Park, S of Tehachapi, 1980 m, 19 Sep 1977, JTS

77160, P. ponderosa, (apt., ovip.); same but JTS 77161, P. jeffreyi, (apt.); Tiger Flat Rd, N of hwy 155,

nr Alta Sierra, 1890 m, 20 Sep 1977, JTS 77165, P. ponderosa, (apt.). LAKE Co.: 5 km S of Lake

Pillsbury, Elk Mt Rd, 640 m, 24 Jul 1977, JTS 77G56, P. jeffreyi, (apt.). LASSEN Co.: 1 km SW of

Susanville on hwy 36, 1460 m, 4 Jul 1977, JTS 77G13, P. jeffreyi, (apt.). LOS ANGELES Co.: Camp

Baldy, 5 Dec 1956, J. MacSwain, “on fir,” (apt.); hwy 2, 7 km NE of jet with Mt Wilson Rd, San

Gabriel Mts, 1530 m, 18 Sep 1977, JTS 77151, P. coulteri, (apt.). MONTEREY Co.: Plaskett Ridge

Rd, Los Padres Natl Forest, 1040 m, 4 Sep 1977, JTS 77111, P. ponderosa, (apt.). PLUMAS Co.: 2

km SE of Graeagle on hwy 89, 1310 m, 26 Jun 1977, JTS 77F10, P. ponderosa, (apt.); Halsted Cmpgd,

Plumas Natl Forest, 19 km NE of Beldon on hwy 70, 790 m, 26 Jun 1977, JTS 77F13, P. ponderosa,

(apt.). RIVERSIDE Co.: 2 km N of Paradise Valley on hwy 74, 1500 m, 9 Sep 1977, JTS 77119, P.

quadrifolia, (apt.). SAN BERNARDINO Co.: 7 km W of Barton Flat on hwy 38, 1950 m, 16 Sep

1977, JTS 77136, P. coulteri, (apt.); San Bernardino Natl Forest, “view” Picnic Area on hwy 18, W

of Rimforest, 1610 m, 17 Sep 1977, JTS 77143, P. ponderosa, (apt.); same but 1620 m, JTS 77144,

1994

SORENSEN: A REVISION OF ESSIGELLA

P. coulteri, (apt., alat.); same but Barton Flat, 29 Aug 1972, D. J. Voegtlin, DJV 67, (apt.); same but

Camp Angeles, 29 Aug 1972, D. J. Voegtlin, DJV 66, P. ponderosa, (apt.); same but Dogwood, 28

Aug 1972, DJV 25, (apt.); same but Snow Valley, DJV 69, P.jejfreyi, (apt.); same but Running Springs,

4 Aug 1973, DJV 77, P. coulteri, (apt.); San Bernardino Mts, nr jet of Jenks Lake Rd & hwy 38, 2010

m, 16 Sep 1977, JTS 77135, P. ponderosa, (apt.); same but 2 km S of jet of hwy 38 & Jenks Lake Rd,

2200 m, JTS 77139, P. jeffreyi, (apt.). SAN DIEGO Co.: 2 km E of Mt Palomar on hwy S6, 1650 m,

11 Sep 1977, JTS 77128, P. attenuata, (apt.); 5 km S of Julian, Harrison Springs Rd, 1460 m, 12 Sep

1977, JTS 77129, P. coulteri, (apt.); lake Cuyamaca, nr Cuyamaca State Park, 1800 m, 12 Sep 1977,

JTS 77130, P. ponderosa, (apt.); Mt Palomar Rd (S6), 3 km S of Mt Palomar, 1530 m, 11 Sep 1977,

JTS 77127, P. coulteri, (apt.). SHASTA Co.: 2 km W of Fall River Mills on hwy 299, 21 Jul 1978,

JTS 78G123, P. ponderosa, (apt.); Hat Creek, 24 Jun 1955, E. O. Essig, P. ponderosa, (apt.). SISKIYOU

Co.: Edson Creek access Rd, Shasta Natl Forest, 8 km W of Bartel on hwy 89, 1160 m, 3 Jul 1977,

JTS 77G10, P. jeffreyi, (apt.). TUOLUMNE Co.: 2 km E of Groveville on hwy 120, 910 m, 30 Jul

1977, JTS 77G63, P. ponderosa, (apt.); Yosemite Natl Park, 17 May 1938, E. O. Essig, P. ponderosa,

(fund.). VENTURA Co.: Mt Pinos Summit, 2680 m, 18 Sep 1977, JTS 77155, P. jeffreyi, (apt.); Reyes

Peak Rd, 10 km E of Pine Summit on hwy 33, 2200 m, 19 Sep 1977, JTS 77159, P. jeffreyi, (apt.).

COUNTY UNCERTAIN: Lake Tahoe, 16 Jul 1969, R. Luck, P. contorta murrayana, (apt.); same but

17 Jul 1969, P. jeffreyi, (apt.). NEVADA. CLARK Co.: Charleston Mts, Lee Canyon Ski Area, 2590

m, 4 Aug 1978, JTS 78H18, P. ponderosa, (apt.). OREGON. JACKSON Co.: 21 km S of Union Creek

on hwy 62, 5 Jul 1978, JTS 78G15, P. ponderosa, (apt., alat.). JOSEPHINE Co.: Grant’s Pass, 2 Sep

1914, H.F.W., P. ponderosa, (apt.). LAKE Co.: 28 km N of Lakeview on hwy 395, 20 Jul 1978, JTS

78G119, P. ponderosa, (apt.).

Essigella (Lambersella) hillerislambersi, NEW SPECIES

Essigella “ hillerislambersi ” Sorensen, 1983: 99 (unpublished manuscript name)

Ph.D. Thesis, University of California at Berkeley, Berkeley, California. 605 p.

Type Series. — Holotype, vivip. apt.; on slide with 1 paratype vivip. apt., ho-

lotype at bottom (6 o’clock position) and mounted inverted; data: CALIFORNIA.

PLUMAS Co.: jet hwys 36 & 89, 1340 m, 19 Jul 1977, J. T. Sorensen (77G23),

Pinus jeffreyi. Holotype deposited in The Natural History Museum, London. Para-

types (all same data as holotype): 8 vivip. apt. on 6 slides including holotype slide;

4 paratype slides with 1 adult vivip. apt. and 1 nymph, only the adults are

paratypes. Paratype slides deposited: 1 slide in NMNH, Washington, D.C.; 1 slide

in CNC, Ottawa, Ontario; 3 slides in Sorensen collection.

Viviparous Apterae.— Morphology: Body length: 2.10-2.64 (2.29 ± 0.14) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 113-145 (132 ± 8) p, processus terminalis: 35-45 (38 ±

3) p\ IV: 90-139 (116 ± 16) p; III: 183-230 (201 ± 13) p\ II: 83-90 (87 ± 2) p. Length of longest

setae on frons: 48-88 (71 ± 10) p, tips incrassate to sharp. Head width: 265-357 (329 ± 20) p. Length

of stylets: 622-969 (821 ± 81) p; ultimate rostral segment: 88-108 (101 ± 5) p , rostral tip reaching

abdominal terga I—II in dorsal view through slide-mounted specimens. Head + pronotum fused, total

length: 428-500 (470 ± 20) p. THORAX: Meso + metanota fused, total length: 400-510 (446 ± 32)

p. ABDOMEN: Tergum I free, length: 158-204 (183 ± 14) m; terga II-VII fused, VIII free. Maximum

distal width of flange on siphunculi: 40-60 (49 ± 5) p\ siphunculi truncated conical, protruding 0.3-

0.6 x maximal distal width. Ventral abdominal sclerites on segments III-IV subquadrate to sublinear,

often centrally constricted; moderate to large, length: 50-90 (67 ± 11) p, 1.2-2.3x diameter of

metatibiae. Dorsal (major + minor) setae (see Fig. 1C) on abdominal terga III-IV: 8-11 (10 ± 1),

tips sharp, in 2 rows with regular positions, lateral-most minor dorsal seta in anterad row; marginal

setae 4-6 each side. Setae on abdominal tergum VIII: 8-11 (9 ± 1), length: 55-98 (70 ± 12) p, tips

incrassate to sharp, in 1-2 rows. Cauda broadly rounded; caudal protuberance absent to poorly

developed; length of longest caudal setae: 93-130 (108 ± \2) p, tips sharp. LEGS: Length of meta-

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

femora: 836-1142 (948 ± 87) /x; metatibiae: 1061-1561 (1276 ± 130) u', longest dorsal setae on central

one-third of metatibiae: 60-113 (92 ± 16) n, 1.5-2.8x diameter of metatibiae, tips blunt to sharp;

approximately equal or very gradually increasing distally, no setal length dimorphism; longest ventral

setae on metatibiae: 33-68 (49 ± 10) n, tips sharp. Length of metabasitarsus: 140-200 (168 ± 15) /z;

metadistitarsus: 208-275 (240 ± 22) p. Ratio of metadistitarsus to metabasitarsus less than 1.9:1,

mean 1.43:1. Pigmentation: Color in life: Body straw yellow, frequently with dark spots; head con-

colorous to orange-brown; tibiae variable, entirely concolorous yellow, to pro- and metatibiae nearly

black, mesotibiae yellow. Slide-mounted specimens: Background of body dorsum very pale to rarely

light brown (usually less than 10, rarely to 30 percent pigment density), unicolorous. Terga at bases

of setae on frons and dorsal (major + minor) setae on abdomen concolorous with surrounding terga,

to subtly darker. Thoracic muscle attachment plates light to moderate brown, often spotted, conspic¬

uous. Dorsal muscle attachment plates of abdomen pale to dark brown, conspicuous. Spiracular plates

and ventral abdominal sclerites light to dark brown, conspicuous, rarely pale, inconspicuous. Siphun-

culi concolorous with surrounding terga, to subtly darker. Cauda, anal and subgenital plates pale,

concolorous with abdominal tergum, to substantially darker. Antennal segments V and IV dark brown,

concolorous, to V and distal one-half of IV dusky; III entirely pale to distal one-third dark brown,

remainder pale; II pale; I concolorous with frons, to subtly darker. Tibiae variable, pro- and metatibiae

usually uniformly light to dark brown, often nearly black, mesotibiae pale; commonly all tibiae

concolorously pale. Distal four-fifths of distitarsi dusky to nearly black with tibiae.

Ultimate Stadium Nymphs of Viviparous Apterae.— Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites. Mesonotum with 2 sclerotized plates extending from muscle attachment sites to

engulf neighboring setal bases; plates usually distinct, faintly to darkly pigmented, diameter approx¬

imately equaling eye length.

Viviparous Alatae.— Slide-mounted specimens: Nonmorphometrics as described for viviparous ap¬

terae except lacking body dorsum pigmentation suite; abdominal terga normally membranous, dorsal

(major + minor) setae between muscle attachment plates infrequently arising from distinct scleroites;

antennal segments often as dark as tibiae, except proximal one-fifth of III pale. Antennal segment III

with 0-2, IV with 0-1, secondary rhinaria. Epicranial suture absent. Forewing medius with single

furcation arising on proximad one-third of vein; cubital base usually arising distad, infrequently

proximad, on subcosta with distance between anal and cubital bases on subcosta usually relatively

large, ca. 30-40 percent or more of anal vein length; usually medius, sometimes cubitus and anal veins

faint, vague to absent. Abdominal terga infrequently with irregular sclerites that engulf or join muscle

attachment plates and dorsal (major + minor) setal bases or scleroites.

Oviparae.— Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae ex¬

cept abdominal terga II-VI fused, lightly to moderately sclerotic, including pleural areas, but VII and

VIII free (rarely VII not free); dorsal demarcations of anterad terga not evident; siphunculi usually

incorporated into sclerotic dorsum, to free; dorsal abdominal muscle attachment plates unicolorous.

Pseudorhinaria on metatibiae irregular, 5-19.

Males, Fundatrices. — Unknown.

Diagnosis.— Essigella ( L .) hillerislambersi and E. (L.)fusca are difficult to dis¬

tinguish. Darker individuals of both can be separated from other Essigella, except

E. (L.) eastopi, by their tibial pigmentation suite [see E. ( L .) eastopi diagnosis].

Dark E. (L.) hillerislambersi usually have a paler background on the body dorsum

than, and lack the developed body dorsum pigmentation of, E. (L.) eastopi. All

three Lambersella species grade into completely pale individuals that can be

differentiated from other pale Essigella by the diagnostics given for E. (L.) eastopi.

Although E. (L.) hillerislambersi is a larger species, with an often longer antennal

segment III, than either E. ( L .) fusca or E. ( L .) eastopi, overlapping morphometric

variation in these species requires that reliable separation use the discriminant

function in the key to the viviparous apterae [couplet 20].

Range. —California, southwestern Oregon, extreme western Nevada (Fig. 4B).

Hosts. —Pinus jejfreyi Greville & Balfour; a single occurrence on P. attenuata

1994

SORENSEN: A REVISION OF ESSIGELLA

Lemmon is a questionable host determination; that sample (77142), which in¬

cluded oviparae, was from a host tree that was very small and lacked cones, but

was among mature P. attenuata.

Discussion. —Essigella ( L.) hillerislambersi is the largest Essigella, and is a rea¬

sonable common species. It is the most multivariately divergent within the sub¬

genus, and appears to be involved in a character displacement phenomenon with

the other E. (Lambersella ) taxa in sympatry. See the discussions of E. (L.) eastopi,

E. (L.) fusca fusca and E. (L.) fused voegtlini for its relationships, unrepeated here.

Coded References to This Tdxon.—Essigelld (L.) hillerisldmbersi has been re¬

ferred to previously by: the coding “Sp. O” (Sorensen 1983 [but not section 2],

1987a, 1992b), “group A” (Sorensen 1983: section 2)and“HRL” (Sorensen 1983);

and by the manuscript name E. “hillerisldmbersi ” in Sorensen (1983).

Etymology dnd Common Nome. — This species is named for the aphidologist

Dirk Hille Ris Lambers, who served as a mentor during my early aphid taxonomy

studies. Common name: Hille Ris Lambers’ Jelfrey pine needle aphid.

Material Examined.— CALIFORNIA. ALPINE Co.: Upper Cascade Creek, E side of Ebbett’s Pass

on hwy 4, 5 km E of summit, 2350 m, 17 Jul 1977, JTS 77G40, P. jeffreyi, (apt.); W side of Monitor

Pass on hwy 89, 2 km E of jet with hwy 4, 1830 m, 17 Jul 1977, JTS 77G38, P. jeffreyi, (apt.). EL

DORADO Co.: Lake Tahoe, Meek’s Bay, 1980 m, 16 Jul 1977, JTS 77G29, P. jeffreyi, (apt.); South

Lake Tahoe, 1950 m, 16 Jul 1977, JTS 77G32, P. jeffreyi, (apt.). INYO Co.: jet of Lake Sabrina Rd

& Southern Calif. Edison Plant 2 Rd, nr Bishop, 2130 m, 1 Aug 1977, JTS 77H4, P. jeffreyi, (apt.).

LOS ANGELES Co.: 3 km SE of Big Pines on hwy 2, E of Blue Ridge Summit, 2200 m, 17 Sep 1977,

JTS 77149, P. jeffreyi, (apt., ovip.). MONO Co.: Deadman Summit on hwy 395, nr Crestview, 2440

m, 31 Jul 1977, JTS 77G72, P. jeffreyi, (apt., alat.); E side of Monitor Pass on hwy 89, 2070 m, 17

Jul 1977, JTS 77G37, P. jeffreyi, (apt.). NEVADA Co.: Prosser Lake Recreation Area, hwy 89, 25 Jun

1977, JTS 77F5, P. jeffreyi, (apt.). PLUMAS Co.: hwy 36, 8 km W of jet with hwy 89, 1460 m, 10

Jul 1977, JTS 77G25, P. jeffreyi, (apt.); (type series) jet of hwys 36 & 89, 1340 m, 10 Jul 1977, JTS

77G23, P. jeffreyi, (apt.). RIVERSIDE Co.: 2 km N of Paradise Valley on hwy 74, 1500 m, 9 Sep

1977, JTS 77118, P. jeffreyi, (apt.). SAN BERNARDINO Co.: San Bernardino Natl Forest, Heart Bar,

30 Aug 1972, D. J. Voegtlin, DJV 73, P. jeffreyi, (apt.); same but Keller Peak Cmpgd, 2200 m, 17

Sep 1977, JTS 77142, P. attenuata, (apt., ovip.); same but JTS 77141, P. jeffreyi, (apt., ovip.); San

Bernardino Mts, 2 km S of jet of hwy 38 & Jenks Lake Rd, 2200 m, 16 Sep 1977, JTS 77139, P.

jeffreyi, (apt.). SAN DIEGO Co.: Pioneer Mail Trail Picnic Area, Cleveland Natl Forest, 3 km N of

Mt Laguna on hwy SI, 1740 m, 12 Sep 1977, JTS 77131, P. jeffreyi, (apt.). SIERRA Co.: 18 km S of

Sierraville on hwy 89, 26 Jun 1977, JTS 77F7, P. jeffreyi, (apt.). TEHAMA Co.: 5 km E of Childs

Meadows on hwy 89, 1460 m, 10 Jul 1977, JTS 77G21, P. jeffreyi, (apt.). TULARE Co.: E of Big

Meadows Cmpgd, Sierra Natl Forest, 2320 m, 13 Aug 1977, JTS 77H13, P. jeffreyi, (apt., alat.).

TUOLUMNE Co.: Yosemite Natl Park, nr Porcupine Rat-Porcupine Creek, 2500 m, 30 Jul 1977,

JTS 77G67, P. jeffreyi, (apt., alat.). VENTURA Co.: Mt Pinos Summit, 2680 m, 18 Sep 1977, JTS

77155, P. jeffreyi, (apt.); Reyes Peak Rd, 10 km E of Pine Summit of hwy 33, 2200 m, 19 Sep 1977,

JTS 77159, P. jeffreyi, (apt.). COUNTY UNCERTAIN: Eagle Peak, Stanislaus Natl Forest, 8 Jul 1979,

D. J. Voegtlin, DJV 558, P. jeffreyi, (apt.); Lake Tahoe, 17 Jul 1969, R. Luck, P. jeffreyi, (apt.).

NEVADA. ORMSBY Co.: E side of Spooner Summit on hwy 50, 1770 m, 16 Jul 1977, JTS 77G33,

P. jeffreyi, (apt.).

Essigella ( Essigella ) Del Guercio, 1909, NEW STATUS

Ldchnus Burmeister, 1835 (in part), Handbuch der Entomologie, Berlin, 2: 91

(genus attributed to Illiger); Essig, 1909, Pomona J. Entomol., 1: 1-4.

“Essigella (.Essigella )” Sorensen, 1983: 73 (unpublished manuscript name) Ph.D.

Thesis, University of California at Berkeley, Berkeley, California. 605 p.

Type Species. — Ldchnus cdlifornicus Essig, 1909, Pomona J. Entomol., 1: 1-4.

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Vol. 70(1)

Viviparous Apterae. —Morphology: Body relatively broad to narrow. Meso- and metanota fused

dorsally; abdominal tergum I usually free but may be fused with meso + metanota, especially laterally.

Dorsal setae (majors and minors) between muscle attachment plates on abdominal segments III-IV

in 1 rarely irregular row with mesad (spinal) setae occasionally slightly anterad or posterad of others

(see Figs. 1E-F); lateral-most dorsal minor seta on each side not anterad (very rarely so) of the

immediately mesad neighbor. Abdominal terga III-IV each with 5-10, rarely to 12, dorsal (major +

minor) and 2-5 (per side) marginal setae; tergum VIII with usually 6, frequently to 8, rarely to 10,

setae. Longest dorsal seta on central one-third of metatibiae to nearly 4 x tibial diameter, tips incrassate

to sharp; these setae not dimorphic in length but sometimes exceptionally variable among specimens,

with nearly equal length, or gradually increasing, along metatibiae. Ventral abdominal sclerites on

segments III-IV reduced (rudimentary), irregular stellate to large, subquadrate, subcircular or subel¬

liptical. Species means for length ratio of metadistitarsus to metabasitarsus varying between 1.47:1

to 1.69:1. Pigmentation: Body dorsum variable, pale to nearly black, unicolorous or variable, but not

strongly mottled; bases of dorsal setae of abdomen concolorous with surrounding terga to substantially

darker. Tibiae varying from entirely pale to nearly black; when darkened, all concolorous or pro- and

mesotibiae paler than metatibiae.

Diagnosis.— See the key to the subgenera of Essigella.

Discussion. — This clade has ecologically transferred to diploxylon pines of the

subgenus Pinus (Sorensen 1987a). The transfer is exclusive of subsection Pon-

derosae pines, although E. (E.) californica, which is relatively polyphagous within

Pinus, feeds on that subsection also. Some E. (.Essigella ) taxa have moved to

Pinaceace hosts other than Pinus [i.e., E. (E.) wilsoni, E. (E.) alyeska]. Some have

partially reinvaded haploxylon pines in the subgenus Strobus, through their rel¬

atively polyphagous feeding habits [i.e., E. (E.) californica, E. (E.) pini\. Others

[i.e., E. ( E .) hoerneri ] have entirely reinvaded subgenus Strobus, in the unoccupied

niches of section Parrya subsection Cembroides. Sorensen (1983) examined the

relationships among the E. (Essigella ) species with discriminant function and

principal component analyses, using morphometric data, and with principal co¬

ordinate analysis, multidimensional scaling and various UPGMA and single¬

linkage clustering algorithms, using coded quantitative and qualitative data.

The phylogenetic analyses here indicate that Essigella (. Essigella ) can be divided

into two series with historical biogeographic relevance: series A, which contains

E. (E.) californica, E. (E.) essigi, E. (E.) hoerneri, E. (E.) pini, and E. (E.) wilsoni;

and series B, which contains E. (E.) alyeska, E. (E.) critchfieldi, E. (E.) knowltoni

braggi, and E. (E.) knowltoni knowltoni. Series A is paraphyletic, and shares hosts

suspected of having an austral origin during the Tertiary [i.e., Madro-Tertiary

geoflora] (Axelrod 1958, 1967; Raven & Axelrod 1978). Essigella (E.) californica,

and E. (E.) hoerneri, however, clearly form a monophyletic species group within

this series. Essigella ( E .) essigi is the least derived species in the subgenus, and

its immediate ancestral node (Fig. 13: node 7) on the phylogenetic tree is shared

by all other E. (Essigella ), making it the functional sister-group for the remainder

of the subgenus.

Series B is monophyletic, with a synapomorphy as a relatively broad head width

[see discussion of E. ( E .) alyeska ]. Members of Series B occur on Pinus contorta

Douglass ex Loudon, Pinus banksiana Lambert and Picea glauca (Moench) Voss;

hosts that have relatively northern distributions in North America (Critchfield &

Little 1966, Little 1971), and are of boreal origin during the Tertiary [i.e., Arcto-

Tertiary geoflora]. Sorensen (1992a) has analyzed the biological groupings and

host associations within the E. ( E .) knowltoni complex, and has found its species,

subspecies and populations to closely overlay the geographic and terpene variance

1994

SORENSEN: A REVISION OF ESSIGELLA

in Pinus contorta and its subspecies [see the discussions under E. (E.) critchfieldi

and E. (E.) knowltoni]. He also notes the presence of character displacement in

both qualitative and multivariate quantitative traits among the taxa in this species

group.

Note that Sorensen (1983) reversed the letters for series A and B, as manuscript

references; in that unpublished work, series A and B were paraphyletic and mono-

phyletic groups, respectively.

Coded References to This Taxon. —Sorensen (1983) referred to this taxon under

the manuscript name “ Essigella (. Essigella ).” Sorensen (1987a) referred to the

assemblage that comprise this taxon as group “III” or, with reference to its sub¬

components, as “I-H-B-A-C-D-E-F-G” [or entire permutations therefore]; in Sor¬

ensen (1992b), the latter refers to it.

Material Examined.—Essigella (E.) alyeska, E. (E.) calif or nica, E. (E.) critchfieldi, E. (E.) essigi,

E. (E.) hoerneri, E. ( E .) knowltoni braggi, E. (E.) knowltoni knowltoni, E. (E.) pini, E. (E.) wilsoni.

Series A

Essigella ( Essigella) essigi Hottes, 1957

Essigella essigi Hottes, 1957: 84, Proc. Biol. Soc. Wash., 70: 84-85.

Primary Type. — Holotype, vivip. alat., on slide with 5 other alat. and 7 apt.,

holotype shown by arrow (near center position among all specimens, 9 o’clock

among alat.); slide data: “ Pinus radiata, Redwood City, California, June 10, 1939,

L. Blanc/Paratype, Essigella holotype essigi F. C. Hottes, Essig.” (Redwood City

is in San Mateo Co.). Holotype deposited in the Essig Museum of Entomology,

University of California at Berkeley, Berkeley, California.

Viviparous Apterae.— Morphology: Body length: 1.33-1.93 (1.62 ± 0.18) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 90-125 (109 ± 11) p, processus terminalis: 23-43 (36 ±

5) m; IV: 60-93 (78 ± 10) p\ III: 110-153 (133 ± 14) p- II: 56-68 (63 ± 4) p. Length of longest setae

on frons: 13-65 (29 ± 13) p, tips incrassate. Head width: 228-275 (249 ± 13) p. Length of stylets:

541-755 (621 ± 56) p\ ultimate rostral segment: 50-78 (63 ± 7) p, rostral tip reaching abdominal

terga I—III in dorsal view through slide-mounted specimens. Head + pronotum fused, total length:

245-388 (324 ± 39) p. THORAX: Meso + metanota fused, combined total length when dorsally

demarcated from abdominal tergum I: 250-377 (312 ± 36) p. ABDOMEN: Tergum I fused with

metanotum, completely so across dorsum (pale individuals) to fused laterally only (dark individuals),

length when dorsally demarcated: 92-143 (123 ± 19) p; terga II-VII fused, VIII free. Maximum distal

width of flange on siphunculi: 15-29 (21 ±4) p\ siphunculi flush with tergum. Ventral abdominal

sclerites on segments III-IV subquadrate, subcircular to subelliptical; length: 35-60 (50 ± 7) p, 1.1-

2.0 x diameter of metatibiae. Dorsal (major + minor) setae (see Fig. IE) on abdominal terga III-IV:

8, very rarely 7 or 9, tips sharp, in 1 row, infrequently with mesad pair of setae posterad; marginal

setae 3, infrequently 2, per segment each side. Setae on abdominal tergum VIII: 6 to rarely 8, length:

5-48 (23 ± 14) p, tips incrassate to sharp, in 1 row. Cauda rounded to broadly rounded; caudal

protuberance moderately developed to nearly absent; length of longest caudal setae: 20-92 (60 ± 19)

p, tips sharp. LEGS: Length of metafemora: 367-581 (476 ± 66) p\ metatibiae: 418-694 (567 ± 87)

p; longest dorsal setae on central one-third of metatibiae: 3-43 (18 ± 11) p, 0.1-1.3 x diameter of

metatibiae, tips incrassate; approximately equal or very gradually increasing distally, no setal length

dimorphism; longest ventral setae on metatibiae: 5-35 (24 ± 9) p, tips sharp. Length of metabasitarsus:

65-98 (85 ± 11) p\ metadistitarsus: 118—163 (144 ± 15) p. Ratio of metadistitarsus to metabasitarsus

less than 1.9:1, mean 1.69:1. Pigmentation: Color in life: Black to green throughout or green with

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Figure 6. Distribution of E. ( E .) essigi [dots (JTS samples), squares (nonJTS samples)], superim¬

posed over the range of its hosts, Pinus attenuata [lighter shading] and Pinus radiata [darker shading

(coastal Santa Cruz, Monterey and San Luis Obispo Counties)].

yellow-green head; frequently with dark dorsal spots when body not dark. Slide-mounted specimens:

Background of body dorsum pale to dark brown or nearly black (to nearly 100 percent pigment

density), unicolorous. Terga at bases of setae on frons and dorsal (major + minor) setae on abdomen

concolorous with surrounding terga, to subtly darker. Thoracic muscle attachment plates and dorsal

muscle attachment plates of abdomen pale, inconspicuous to dark brown, conspicuous. Spiracular

plates and ventral abdominal sclerites pale to nearly black. Siphunculi concolorous with surrounding

terga. Cauda, anal and subgenital plates subtly to substantially darker than abdominal terga. Antennal

segments V and IV dusky to moderate brown, concolorous; III entirely pale to dusky on distal one-

third, remainder pale; II concolorous with proximal III, to subtly darker; I concolorous with frons.

Pro-, meso- and metatibiae concolorous, and usually equivalent to abdominal terga, sometimes subtly

lighter (dark individuals), rarely darker. Distitarsi evenly moderate brown, sometimes subtly paler at

proximal tip.

Ultimate Stadium Nymphs of Viviparous Apterae. - Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

1994

SORENSEN: A REVISION OF ESSIGELLA

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites; meso- and metathorax not fused. Mesonotum with 2 sclerotized plates extending

from muscle attachment sites to engulf neighboring setal bases; plates usually heavily, to faintly,

pigmented, diameter approximately equaling eye length.

Viviparous Alatae. -Slide-mounted specimens: Nonmorphometrics as described for viviparous ap-

terae except lacking body dorsum pigmentation suite, and meso- and metathorax not fused; abdominal

terga normally membranous, dorsal (major + minor) setae between muscle attachment plates fre¬

quently arising from distinct scleroites; antennal segments often as dark as tibiae, except proximal

one-fifth of III pale. Antennal segment III with 2-3, IV with 0-1, secondary rhinaria. Epicranial suture

usually strongly developed, to absent. Forewing medius usually single, infrequently single furcation

arising on distad one-third of vein; cubital base usually arising distad, infrequently proximad, on

subcosta with distance between anal and cubital bases on subcosta usually relatively large, ca. 30-40

percent or more of anal vein length; medius, especially cubitus and anal veins usually distinct, except

infrequently proximad 10-15 percent vague. Abdominal terga infrequently with irregular sclerites that

engulf or join muscle attachment plates and dorsal (major + minor) setal bases or scleroites.

Oviparae, Males, Fundatrices.— Unknown.

Diagnosis. — Adult viviparous apterae of E. (E.) essigi can be identified by the

unique additional fusion of abdominal tergum I to fused meso + metanota. They

vary from entirely pale to dark brown [like E. ( E.) critchfleldi and some E. ( E .)

knowltoni knowltoni], and the fusion of abdominal tergum I varies inversely with

pigmentation: it extends entirely across the dorsum in pale individuals, but is

restricted to the lateral edges of the dorsum in dark specimens. The forewing

medius of alates usually is single, or occasionally 1-branched with the furcation

distad and closer to the posterad margin of the wing than to the subcosta. This

alate character is similar in E. (E.) pini [see that diagnosis] and potentially can

be confused in E. (E.) knowltoni knowltoni and E. (E.) alyeska.

Range. —California and southwestern Oregon (Fig. 6).

Hosts.—Pinus radiata D. Don and P. attenuata Lemmon, both subsection

Oocarpae pines that hybridize (W. Libby, personal communication). Although E.

(E.) essigi is commonly found on closed-cone pines, it has not been found on P.

muricata D. Don, despite extensive collecting; its appearance on that pine would

not be surprising, however. Also, one collection (77G12) exists from P. ponderosa,

at a site about 50 mi east, by air, of the nearest stand of P. attenuata, near the

southern Modoc-Siskiyou county border (Critchfield & Little 1966: map 58) in

northwest California. Another collection (7718) exists from P. sabiniana, possibly

a contaminant, at the same location and immediately after a collection (7717)

from P. attenuata. I suspect that the locations where E. (E.) essigi can be found

in California have probably increased substantially in recent years because of the

extensive landscape planting of Pinus radiata.

Discussion.—Essigella (E.) essigi is relatively homogeneous in morphology,

although specimens from southwest Oregon and the northern Californian coast

tend to be very slightly more linear than those near the San Francisco Bay area

and south. The autapomorphic fusion of abdominal tergum I in this species is

incomplete dorsally on darker specimens, probably due to an increased scleroti-

zation of the body dorsum; the break may be necessary for articulation (?) of the

more rigid tergum on those individuals. Subtle differences between coastal pop¬

ulations on P. radiata, and inland populations on P. attenuata should be examined

in more detail with isozyme or nucleic acid techniques.

Hottes (1957: 85) stated “I am sure that specimens of this species [E. (E.) essigi ]

were part of the original material from which Essig described Lachnus californicus,

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Vol. 70(1)

although there is no actual proof in the remaining cotype material.” He based

this supposition on Essig’s illustration (Essig 1909: fig. 2), which failed to indicate

long tibial setae. Unfortunately, Hotte’s reliance upon length of the dorsal setae

on the tibia was entirely misguided. I have found no evidence to support his

supposition.

The phylogenetic position of E. ( E.) essigi within the subgenus is problematic.

Clustering analyses on qualitative coded characters (Sorensen 1983) suggest it is

probably primitive within E. {Essigella) because its similarities to other taxa are

mostly plesiomorphies at the level of the subgenus. Ordinations on morphometric

data indicate that it is close to E. ( E .) pini and E. (E.) wilsoni in ordinant space;

the evolutionary aspects of this are discussed in Sorensen (1992b). Cladistic anal¬

ysis of coded data (unpublished data) suggest that E. (E.) essigi is either para-

phyletically one of the more primitive E. (Essigella ), along with E. (E.) pini, or

that it potentially forms a monophyletic subgroup, which is the sister-group to

the remainder of the subgenus, with E. (E.) pini.

Intuitively, I consider E. (E.) essigi to be closest to E. ( E .) pini, but I am uncertain

of the exact relationship between them. Both share reduction of the alate medius

to a single vein, but I am reluctant to accept the trait as a convincing, nonhomo-

plasious synapomorphy. I also suspect the genetic compatibility of subsection

Oocarpae and Australes pines [the latter chiefly hosts E. (E.) pini ] suggests a

potentially common biogeographic origin; see the section on ecological collabo¬

ration of phylogenetic hypotheses for comments.

Coded References to This Taxon. —Essigella (E.) essigi has been referred to

previously by: the coding “Sp. I” (Sorensen 1983, 1987, 1992b) and “ESSG”

(Sorensen 1983), and by the name E. essigi in Sorensen (1983).

Etymology and Common Name. — Hottes (1957) apparently named this species

for the aphidologist E. O. Essig, presumably because he described the first Essi¬

gella, E. ( E.) calif or nica, albeit as a Lachnus. Common name: Essig’s closed-cone

pine needle aphid [see etymology for E. (E.) californica ].

Material Examined.— CALIFORNIA. ALAMEDA Co.: Berkeley, 10 Nov 1935, E. O. Essig, P.

radiata, (apt.); same but 15 Feb 1982, J. T. Sorensen, P. radiata, (apt.). DEL NORTE Co.: 16 air km

NWW of Crescent City on hwy 199, Six Rivers Natl Forest, 4 Jul 1978, JTS 78G6, P. attenuata, (apt.,

alat.). LAKE Co.: 21 km N of Upper Lake, Elk Mt Rd, 1030 m, 24 Jul 1977, JTS 77G60, P. attenuata,

(apt., alat.); same but 23 km N of Upper Lake, 1160 m, JTS 77G59, (apt.); same but 26 km N of

Upper Lake, JTS 77G58, (apt.). MODOC Co.: E side of Cedar Pass, 29 km E of Alturas, 1890 m, 3

Jul 1977, JTS 77G12, P. ponderosa, (apt.). MONTEREY Co.: 3 km N of Point Lobos State Park

Reserve on hwy 1, 29 Dec 1978, JTS 78L1, P. radiata, (apt.); Carmel, 16 Jun 1973, D. J. Voegtlin,

DJV 25, P. radiata, (apt.); Lockwood-San Ardo Rd, 13 km SW of jet with Paris Valley Rd, 550 m,

4 Sep 1977, JTS 7717, P. attenuata, (apt.); same but JTS 7718, P. sabiniana, (apt.); Monterey, 18 Jun

1973, D. J. Voegtlin, DJV 24, P. radiata, (apt.); same but 19 Feb 1974, T. Kono, CDFA 79B20-10-

2, (apt.). NAPA Co.: 3 km N of Angwin, Howell Mt Rd, 4 Feb 1978, JTS 79B2, P. attenuata, (apt.).

PLACER Co.: 6 km W of Dutch Flat on hwy 80, 2 Aug 1978, JTS 78H2, P. attenuata, (apt.). SAN

LUIS OBISPO Co.: Cambria Pines, 5 Sep 1977, JTS 77112, P. radiata, (apt.). SAN MATEO Co.:

(paratype) Redwood City, 10 Jun 1939, L. Blanc, P. radiata, (apt., alat.). SANTA CLARA Co.: (paratype)

Palo Alto, Stanford Univ., 30 Mar 1938, E. O. Essig, P. radiata, (apt.,); (paratype) same but 25 Apr

1930, P.S.B., (apt.); Morgan Hill, 14 Oct 1942, Bell, CDFA 42J10, P. attenuata, (apt.). SISKIYOU

Co.: Snowman Hill Summit on hwy 89, 8 km E of jet with hwy 5, 1360 m, 2 Jul 1977, JTS 77G3,

P. attenuata, (apt.). TRINITY Co.: Junction City, 11 km of Weaverville on hwy 299, 430 m, 20 Aug

1977, JTS 77H23, P. attenuata, (apt.). OREGON. JOSEPHINE Co.: 2 km N of O’brien on hwy 199,

4 Jul 1978, JTS 78G11, P. attenuata, (apt.).

1994

SORENSEN: A REVISION OF ESSIGELLA

Essigella ( Essigella) pini Wilson, 1919

Essigella pini Wilson, 1919: 2, Entomol. News, 30: 2-3.

Essigella patchae Hottes, 1957: 98, Proc. Biol. Soc. Wash., 70: 98-100. NEW

SYNONYM.

Primary Type. — Lectotype, vivip. alat., on slide alone; data: “(Lectotype)/82-

14/11, Essigella pini Wilson, Cotype, Pinus virginiana, Plummer’s Is., Md., May

27, 1914.” Lectotype deposited in the Granovsky Collection, Department of

Entomology, Fisheries & Wildlife, University of Minnesota, St. Paul, Minnesota.

Hottes (1957: 103) designated a vivip. alat., from the Granovsky collection as

lectotype. A slide that is so labeled does exist, although I doubt that Hottes

personally labeled it because the printing does not match his, and he did not label

other lectotypes in this genus; I have seen this specimen and consider it the

lectotype.

Viviparous Apterae.— Morphology: Body length: 1.57-2.03 (1.79 ± 0.15) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 98-133 (115 ± 9) p, processus terminalis: 25-38 (31 ±

4) m; IV: 73-100 (84 ± 8) HI: 110-158 (136 ± 16) p\ II: 63-79 (68 ± 4) p. Length of longest setae

on frons: 15-73 (29 ± 16) p, tips incrassate. Head width: 245-316 (276 ± 19) p. Length of stylets:

541-663 (572 ± 34) p\ ultimate rostral segment: 55-75 (67 ± 5) p, rostral tip reaching abdominal

terga I—II in dorsal view through slide-mounted specimens. Head + pronotum fused, total length:

326-454 (400 ± 36 ) /x. THORAX: Meso + metanota fused, total length: 265-367 (327 ± 33) p.

ABDOMEN: Tergum I free, length: 112-163 (134 ± 15) p\ terga II-VII fused, VIII free. Maximum

distal width of flange on siphunculi: 15-35 (28 ± 5) p; siphunculi usually flush to slightly protruding

to 0.3 x maximal distal width. Ventral abdominal sclerites on segments III-IV usually subcircular,

subquadrate to subelliptical, sometimes irregular, asterisk-shaped, or constricted anteriorly; length:

40-75 (54 ± 8) p, 1.0-2.Ox diameter of metatibiae. Dorsal (major + minor) setae (see Fig. IF) on

abdominal terga III-IV: 6, infrequently 7, tips sharp, in 1 row; marginal setae 2 per segment, each

side. Setae on abdominal tergum VIII: 6, length: 8-25 (13 ± 5) p, tips incrassate to sharp, in 1 row.

Cauda rounded; caudal protuberance well developed, often pointed, to moderately developed; length

of longest caudal setae: 43-120 (75 ± 20) p, tips sharp. LEGS: Length of metafemora: 398-581 (486

± 57) p ; metatibiae: 561-831 (675 ± 79) p\ longest dorsal setae on central one-third of metatibiae:

11-33 (17 ± 6) p, 0.3-1.Ox diameter of metatibiae, tips usually incrassate, infrequently sharp; ap¬

proximately equal or very gradually increasing distally, no setal length dimorphism; longest ventral

setae on metatibiae: 23-68 (35 ± 11) p, tips sharp. Length of metabasitarsus: 79-103 (89 ± 6) p\

metadistitarsus: 138-163 (147 ± 9) p. Ratio of metadistitarsus to metabasitarsus less than 1.9:1, mean

1.65:1. Pigmentation: Color in life: Green with yellow-orange to red-orange head (from notes on C.

F. Smith slides). Slide-mounted specimens: Background of body dorsum pale (to 10 percent pigment

density), unicolorous. Terga at bases of setae on frons and dorsal (major + minor) setae on abdomen

concolorous with surrounding terga. Thoracic muscle attachment plates and dorsal muscle attachment

plates of abdomen pale, inconspicuous. Spiracular plates and ventral abdominal sclerites pale, to

moderate brown, conspicuous. Siphunculi concolorous with surrounding terga. Cauda, anal and subgenital

plates pale, concolorous with, to subtly dusky and slightly darker than abdominal terga. Antennal

segments V and IV pale to light brown, concolorous; III entirely pale to distal one-third concolorous

with V and IV; II concolorous with proximal III; I concolorous with frons. Pro-, meso- and metatibiae

usually pale, concolorous and equivalent to body dorsum, infrequently entire tibiae slightly dusky,

subtly darker than dorsum. Distitarsi entirely pale to subtly dusky on distal one-third.

Ultimate Stadium Nymphs of Viviparous Apterae. — Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites. Mesonotum with, very rarely lacking, 2 sclerotized plates extending from muscle

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

attachment sites to engulf neighboring setal bases; plates faintly to heavily pigmented, diameter ap¬

proximately equaling eye length.

Viviparous Alatae. -Slide-mounted specimens: Nonmorphometrics as described for viviparous ap-

terae except lacking body dorsum pigmentation suite; abdominal terga normally membranous, dorsal

(major + minor) setae between muscle attachment plates occasionally arising from distinct scleroites;

antennal segments often as dark as tibiae, except proximal one-fifth of III pale. Antennal segment III

with 2-3, IV with 0, secondary rhinaria. Epicranial suture vaguely to strongly developed. Forewing

medius usually single, infrequently single furcation arising on distad one-third of vein; cubital base

usually arising distad on subcosta with distance between anal and cubital bases on subcosta usually

relatively large, ca. 30-40 percent or more of anal vein length; medius, especially cubitus and anal

veins distinct, except infrequently proximad 10-15 percent vague. Abdominal terga infrequently with

irregular sclerites that engulf or join muscle attachment plates and dorsal (major + minor) setal bases

or scleroites.

Oviparae. -Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae, ab¬

dominal terga II-VII fused, moderately sclerotic, including pleural areas, tergum VIII free (uncom¬

monly tergum VII free, demarcations of II-VI evident laterally); dorsal demarcations of anterad terga

sometimes evident; siphunculi incorporated into sclerotic field, to free; dorsal abdominal muscle

attachment plates unicolorous. Pseudorhinaria on metatibiae irregular, 8-15.

Males, Funda.trices. — Unknown.

Diagnosis. — This species is pale and may be confused with other pale Essigella-,

it requires the combination of several characters for identification. Essigella (E.)

pini can be separated from all Essigella, except E. (E.) californica and E. (E.)

hoerneri, by having six (Fig. IF), instead or eight or more, dorsal (major + minor)

setae on abdominal terga III-IV. It differs from E. (E.) calif ornica and E. ( E .)

hoerneri by having usually large subcircular-subquadrate, rather than usually small

irregular, ventral abdominal sclerites on abdominal segments III-IV, and by hav¬

ing usually large invasive, instead of small noninvasive, mesonotal muscle at¬

tachment plates on later stadia nymphs of apterae. The mean lengths of antennal

segments III and the metatibiae are shorter, but overlapping, in proportion to

body length in E. (E.) pini than in either E. (E.) calif ornica or E. ( E .) hoerneri.

The caudal protuberance of E. ( E .) pini also is often abnormally long and pointed,

but the trait is not an entirely satisfactory discriminator. Alates of E. ( E.) pini

differ from other species, except E. (E.) essigi, in having the medius usually single,

or infrequently 1-branched with the furcation exceptionally distad; but E. (E.)

knowltoni knowltoni has also rarely shown this condition. Although the relative

stability of the trend to a single medius for E. {E.) pini and E. (E.) essigi seems

a reasonable partial diagnostic for those species, unknown alate morphs and

interspecific variance in several Essigella species make discriminatory use of

venation potentially questionable.

Synonyms. —Essigella patchae Hottes, NEW SYNONYM: holotype, vivip. alat.,

as a single fragmented specimen on the slide; data: MAINE. PENOBSCOT Co.:

Stillwater, 4 Jul 1909, Pinus strobus L. Essigella patchae holotype deposited in

the NMNH.

Range. —Eastern U.S.; one record from southern Quebec (Fig. 7).

Hosts. —Notably Pinus virginiana P. Miller, P. taeda L., P. strobus L.; presum¬

ably many species of Pinus subsection Australes; subsection Sylvestres pines also

recorded as hosts. Note that because E. (E.) pini is the only Essigella that I have

not personally collected, during extensive sampling of the western Nearctic (Sor¬

ensen 1983), I cannot attest to the accuracy of determination of its hosts, as with

other Essigella. Indeed, because the aphid occurs only in the eastern U.S., and it

1994

SORENSEN: A REVISION OF ESSIGELLA

Figure 7. Distribution of E. ( E .) pini [squares (nonJTS samples)], superimposed over the ranges

of its hosts, Pinus strobus [darker + moderate shading] and an amalgamation of subsection Australes

plus eastern subsection Contortae pines [lighter + moderate shading] (moderate shading indicates the

distributional overlap of hosts).

could not often be successfully identified until now (see discussion), many western

pine species attributed as its hosts are in error.

Discussion.—Essigella ( E .) pini, known from the eastern Nearctic only, has

been the most confused Essigella with regard to misidentifications. This is, no

doubt, due in large part to Hottes’ (1957) erroneous key. Using that key, it is

conceivable that at least some individuals (albeit, small and pale in several in¬

stances) of all species, except E. ( L .) hillerislambersi, might key out to Hottes’

“is. pint”

References to Essigella “pini” from the western U.S. and Canada (i.e., Knowlton

1930, Gillette & Palmer 1931, Palmer 1952, Smith & Parron 1978) are in error

and clearly do not represent that species. I cannot determine exactly to what they

correctly refer, because adequate diagnostics are not mentioned. Such references

evoke potential confusion with E. ( E .) californica, E. (is.) hoerneri, E. (is.) wilsoni,

E. (L.) fusca fusca, E. (is.) knowltoni knowltoni and E. (A.) kirki, due to the

geography involved and the earlier erroneous diagnostic fixation on the length of

the dorsal setae of the metatibiae. A single alate from Quebec, captured in a

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Vol. 70(1)

Malaise trap (F. W. Quednau, personal communication), appears to be the only

Canadian record of this species. Patti & Fox (1981a, b) discuss the seasonal

occurrence and intratree distribution of E. (E .) pini in South Carolina.

Essigella ( E .) pini appears to be relatively homogeneous morphologically. Be¬

cause it was not extensively sampled over its range during this study, however,

knowledge of its variation is drawn only from collections by others, which have

relatively limited geographic spread and continuity. It shows infrequent variability

in reduction of the ventral abdominal sclerites on segments III-IV, but this trait

is paralleled within other species.

Placement of E. (E.) pini within the subgenus was confusing during analysis;

for comments, see the discussion of E. ( E .) essigi. It shows several qualitative

loss-reduction apomorphies that are considered to be homoplasious with E. (E.)

californica and E. (E.) hoerneri, and a few others with E. ( E .) wilsoni and E. ( E.)

alyeska. The fusion of abdominal terga on its oviparae is also problematic [see

character discussion section].

Coded References to This Taxon. —Essigella (E.) pini has been referred to pre¬

viously by: the coding “Sp. H” (Sorensen 1983, 1987a, 1992b) and “PINI” (Sor¬

ensen 1983), and by the name E. pini in Sorensen (1983).

Etymology and Common Name. —Wilson (1919) presumably named this spe¬

cies with reference to the host genus, Pinus. Common name: the eastern pine

needle aphid; although Palmer (1952: 16) refers to this species as “The Speckled

Pine Needle Aphid,” the common name indicated here is more appropriate and

less confusing because many Essigella are speckled.

Material Examined. — ALABAMA. BARBOUR Co.: Eufaula, 10 Feb 1876, Pinus sp., (apt.). FLOR¬

IDA. ALACHUA Co.: Gainesville, 23 Mar 1928, A. Tissot, ANT F323-28, P. taeda, (apt., alat.); same

but no date, ANT F886-32, (apt., alat.). COLUMBIA Co.: 22 Mar 1973, G. Hertel, P. elliottii En-

gelmann, (apt.); 26 May 1972, G. Hertel, P. elliottii, (alat.). SAINT JOHNS Co.: St. Augustine, 10

May 1945, D. & B. Darry, P. taeda, (apt.); same but 24 May 1945, D. & B. Darry, (alat.). SEMINOLE

Co.: Sanford, 23 Feb 1929, A. Tissot, ANT F480-29, P. taeda, (alat.). MAINE. PENOBSCOT Co.:

Stillwater, 4 Jul 1909, E. M. Patch, MAES 46-09, P. strobus, (alat.). MARYLAND. BALTIMORE

Co.: Sheppard Pratt, 3 Aug 1974, A. Scarbough, (alat.). PRINCE GEORGES Co.: Beltsville, 19 Jun

1978, W of Cantelo, yellow pan trap, (alat.). COUNTY UNCERTAIN: (lectoype) Plummer’s Island,

27 Apr 1914, P. virginiana, (apt., alat.). NORTH CAROLINA. ALLEGANY Co.: Gladesville, 17 Jun

1959, D. A. Young, Pinus sp., (apt.). BANCOMBE Co.: Twin Tunnels, (Blue Ridge) Parkway, 29 Jul

1958, C. F. Smith, CFS 58-347, Pinus sp., (apt.). CHEROKEE Co.: N of Andrews, 24 Jul 1958, C.

F. Smith, CFS 58-309, Pinus sp., (apt., alat.). DURHAM Co.: Durham, 10 Jan 1978, D. Whitman,

P. lambertiana, (apt.); same but 22 Oct 1959, S.S.T.,P. taeda, (apt.); same but 8 Jan 1979, J. Richmond,

(apt.). MACON Co.: Highlands, Mt Satulah, 29 Sep 1970, C. F. Smith C. S. Smith & C. Sullivan, P.

rigida P. Miller (alat.). MOORE Co.: West End, 30 Oct 1958, S.S.T., Pinus sp., (apt., alat.). RICH¬

MOND Co.: Norman, 30 Oct 1958, S.S.T., Pinus sp., (apt.). WAKE Co.: McCullers, 18 May 1967,

C. F. Smith, CFS 67-28b, P. taeda, (apt.); Umstead Park, 30 May 1960, C. F. Smith, CFS 60-303, P.

taeda, (apt., alat.). WASHINGTON Co.: Roper, 10 Feb 1975, C. G. Livingston, P. taeda, (apt.).

WILKES Co.: McGrady, 14 Oct 1963, C. F. & C. S. Smith, CFS 63-166, (alat.). YANCEY Co.: 2.4

km (1.5 mi) E of Mt Mitchell State Park entrance, 23 Jul 1970, G. Fedde, P. pungens Lambert (apt.,

alat.). Crabtree Meadows, (Blue Ridge) Parkway, 12 Oct 1958, S.O.T., P. strobus, (apt., ovip.); same

but Pinus sp., (apt.). OKLAHOMA. LATIMER Co.: Robber’s Cave State Park, 19 Sep 1957, Van

Cleave, P. echinata P. Miller (apt., alat.). McCURTAIN Co.: Broken Bow, 13 Sep 1960, Van Cleave,

P. echinata, (apt.). PENNSYLVANIA. CENTRE Co.: State College, 3 Oct 1959, J. Pepper, P. sylvestris

L., P. resinosa Aiton, P. strobus, (apt., alat.). SOUTH CAROLINA. OCONEE Co.: Seneca, 26 May

1962, R. Eikenbarry, Pinus sp., (apt.). PICKENS Co.: Clemson, 4 Apr 1973, K. Griffith, Pinus sp.,

(apt., alat.); same but 6 Jun 1977, W of Hood, P. taeda, (alat.). VIRGINIA. MONTGOMERY Co.:

Blacksburg, 6 Feb 1967, W. A. Allen, P. taeda, (apt.). CANADA. QUEBEC: Mt St. Hilaire, Cte

Rouville, Meteo, 5 Jul 1979, R. Roy, Malaise trap (alat.).

1994

SORENSEN: A REVISION OF ESSIGELLA

Essigella ( Essigella) californica (Essig), 1909

Lachnus californicus Essig, 1909: 1, Pomona J. Entomol., 1: 1-4.

Essigella californica Del Guercio, 1909: 328, Rivista di Patologia Vegetale, Anno

III Num. 20-21: 328-329.

Essigella claremontiana Hottes, 1957: 79, Proc. Biol. Soc. Wash., 70: 79-81.

NEW SYNONYM.

Essigella cocheta Hottes, 1957: 82, Proc. Biol. Soc. Wash., 70: 82-84. NEW

SYNONYM.

Essigella monelli Hottes, 1957: 95, Proc. Biol. Soc. Wash., 70: 95-96. NEW

SYNONYM.

Essigella pineti Hottes, 1957: 101, Proc. Biol. Soc. Wash., 70: 101-102. NEW

SYNONYM.

Essigella swaini Hottes, 1957: 105, Proc. Biol. Soc. Wash., 70: 105-106. NEW

SYNONYM.

Primary Type. — Lectotype, vivip. alat., on slide alone; data: “Monterey pine,

Claremont, Cal., Feb. 14, 1909, E.O.E./type/Cotype, Lachnus californicus Essig,

Essig/[on back] Lectotype of Hottes, J. T. Sorensen ‘82” (Claremont is in Los

Angeles Co.). Lectotype deposited in the Essig Museum of Entomology, University

of California at Berkeley, Berkeley, California.

The extent of the original type series is somewhat confused; but the [1909]

series must have involved an ovipara (see discussion). The series was scattered

and possibly adulterated by the addition of material collected in 1911 (“47” slides),

which may be involved with Essig’s (1912) redescription (see Hottes 1957: 78).

Hottes (1957: 78) mentions a lectotype and describes the slide as thick, but the

apparent slide merely bears a small label stating “type” below the coverslip. The

label is asymmetrically placed, and could have had a prefix “lecto” removed.

There are also, however, two other slides, deposited in the NMNH, bearing “type”

in blue ink on the right-hand label that are part of the 1911 “47” series. I deduced

what must be Hottes’ lectotype based upon his description of the slide and its

location, and I have labeled the slide as lectotype.

Viviparous Apterae.— Morphology: Body length: 1.30-2.38 (1.90 ± 0.24) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 103-155 (128 ± 11) /x, processus terminalis: 30-48 (37

± 5) p\ IV: 88-138 (109 ± 14) p; III: 135-250 (194 ± 31) u; II: 63-88 (77 ± 8) p. Length of longest

setae on frons: 6-73 (39 ± 18) p, tips incrassate to sharp. Head width: 214-347 (270 ± 26) p. Length

of stylets: 551-806 (688 ± 71) /u.; ultimate rostral segment: 70-98 (83 ± 8) p, rostral tip reaching

abdominal terga I—II, occasionally III, in dorsal view through slide-mounted specimens. Head +

pronotum fused, total length: 316-510 (393 ± 42) p. THORAX: Meso + metanota fused, total length:

245-571 (365 ± 57) p. ABDOMEN: Tergum I free, length: 82-194 (131 ± 23) p; terga II-VII fused,

VIII free. Maximum distal width of flange on siphunculi: 25-45 (36 ± 5) p\ siphunculi flush to truncated

conical, protrusion to 0.7 x maximal distal width. Ventral abdominal sclerites on segments III-IV

usually irregular, to subcircular when small (length less than 0.6 x metatibial diameter), subquadrate

when large (length greater than 1.0 x metatibial diameter); length: 8-63 (23 ± 14) p, 0.3-1 . 1 x diameter

of metatibiae. Dorsal (major + minor) setae (see Fig. IF) on abdominal terga III-IV: 6, rarely 7, tips

incrassate to sharp, in 1 row; marginal setae 2 each side. Setae on abdominal tergum VIII: 6, occasionally

7, infrequently 8, length: 8-85 (36 ± 20) p, tips incrassate to sharp, in 1 row. Cauda rounded; caudal

protuberance moderately to poorly developed, sometimes absent; length of longest caudal setae: 48-

103 (75 ± 12) p, tips sharp. LEGS: Length of metafemora: 469-938 (718 ± 126) p\ metatibiae: 653-

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

1397 (1042 ± 195) fx; longest dorsal setae on central one-third of metatibiae: 8-118 (58 ± 33) n, tips

0.1-3.0 x diameter of metatibiae, tips incrassate to sharp; approximately equal or very gradually

increasing distally, no setal length dimorphism, but very rarely with dorsal setae breaking on proximad

one-third of metatibiae to a ca. 30-50 percent increase in length; longest ventral setae on metatibiae:

14-73 (35 ± 14) n, tips sharp. Length of metabasitarsus: 84-148 (122 ± 16) u; metadistitarsus: 148—

230(191 ± 20) /i. Ratio of metadistitarsus to metabasitarsus less than 1.9:1, mean 1.57:1. Pigmentation:

Color in life: Thorax gray-green, abdomen lime green, legs light to dark brown, or straw yellow

throughout; dorsal spots absent to brown. Slide-mounted specimens: Background of body dorsum

pale to moderate brown (usually to 20, infrequently to 40 percent pigment density), unicolorous. Terga

at bases of setae on frons and dorsal (major + minor) setae on abdomen concolorous with surrounding

terga, to conspicuously darker. Thoracic muscle attachment plates and dorsal muscle attachment plates

of abdomen, spiracular plates and ventral abdominal sclerites pale, inconspicuous, to dark brown,

conspicuous. Siphunculi concolorous with surrounding terga, to substantially darker. Cauda, anal and

subgenital plates concolorous with abdominal terga, to substantially darker. Antennal segments V and

IY subtly dusky distally, pale proximally, to entirely dusky; III entirely very pale to subtly dusky on

distal one-third, remainder pale; II concolorous with proximal III, to subtly darker; I concolorous

with frons. Pro-, meso- and metatibiae usually concolorous, evenly pale or pale with subtly dusky

distal tip, to evenly dark brown; or metatibiae subtly to substantially darker than pro- and mesotibiae.

Distitarsi dusky on distal one-third, pale proximally, to evenly dark brown with tibiae.

Ultimate Stadium Nymphs of Viviparous Apterae.— Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites. Mesonotum lacking 2 sclerotized plates extending from muscle attachment sites to

engulf neighboring setal bases; area surrounding muscle attachment sites membranous.

Viviparous Alatae.— Slide-mounted specimens: Nonmorphometrics as described for viviparous ap¬

terae except lacking body dorsum pigmentation suite; abdominal terga normally membranous, dorsal

(major + minor) setae between muscle attachment plates occasionally arising from distinct scleroites;

antennal segments often as dark as tibiae, except proximal one-fifth of III pale. Antennal segment III

with 0-5, IV with 0-3, secondary rhinaria. Epicranial suture strongly developed. Forewing medius

with single furcation arising on proximad, very rarely on central, one-third of vein; cubital base arising

proximad, rarely distad, on subcosta with distance between anal and cubital bases on subcosta usually

relatively small, ca. 20-30 percent or less of anal vein length; medius, especially cubitus and anal veins

usually distinct, except infrequently proximad 10-15 percent vague. Abdominal terga lacking irregular

sclerites that engulf or join muscle attachment plates and dorsal (major + minor) setal bases or

scleroites.

Oviparae. — Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae ex¬

cept abdominal dorsum membranous with irregular transverse sclerites containing dorsal (major +

minor) setae, occasionally dorsal muscle attachment plates, on each tergum; marginal setae usually

on separate scleroites, occasionally engulfed by dorsal sclerites on posterad terga; siphuncular cones

sclerotized, regular, separated from other dorsal sclerotic fields; dorsal abdominal muscle attachment

plates unicolorous. Rarely with abdominal II-VI sclerotic/fused, terga VII and VIII free; dorsal de¬

marcations of anterad terga then evident and siphuncular cones surrounded closely by, sometimes

engulfed by, sclerotic fields. Pseudorhinaria on metatibiae irregular, 12-21; also on procoxa and pro-

and metafemora (Essig 1909: figs. 2a-b, 2d).

Males.— Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae except

body slightly smaller, with slightly longer antennae and tibiae; dorsal demarcations of abdominal terga

evident. Antennal segment III with 13-15, IV with 8-10, secondary rhinaria.

Fundatrices. -Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae

except siphunculi absent; longest dorsal setae on central part of metatibiae 0.5-1.5x tibial diameter.

Diagnosis. —Essigella (E. ) californica requires the combination of several char¬

acters for identification; individuals usually are pale and may be confused with

other pale Essigella. Essigella (E. ) californica can be separated from all Essigella,

except E. (E .) hoerneri and E. ( E .) pini by having six (Fig. IF), instead of eight

or more, dorsal (major + minor) setae on abdominal terga III-IV. Essigella (E.)

californica differs from E. (E.) pini by having usually small and irregular, rather

1994

SORENSEN: A REVISION OF ESSIGELLA

than large, ventral abdominal sclerites on abdominal segments III—IV, and also

small and noninvasive, rather than large and'invasive, muscle attachment plates

on the mesonotum of later stadia nymphs of apterae. Alates differ from those of

E. (E.) pini by having the forewing medius always 1-branched with the furcation

proximad, near the subcosta, instead of usually unbranched or occasionally

1-branched but with the furcation no more distad than half way between the

subcosta and the posterad margin of the wing, as in E. (E.) pini. Oviparae of E.

( E .) californica and E. (E.) pini differ in the sclerotic pattern of the abdominal

dorsum; in E. ( E .) pini, usually all terga, except terga I and VIII, are fused; in E.

(. E .) californica, usually all terga are separate (as independent sclerotic bands), or

infrequently segments II-VI are (sometimes only partially) united, with evident

segmental demarcations, but terga VII and VIII remain independent [E. ( E .) pini

rarely shows the latter condition].

Essigella (E.) californica and E. (E.) hoerneri are difficult to distinguish; the

qualitative characters listed above for alates, oviparae and nymphs are identical

between them. Although E. (E.) californica has a shorter rostrum, narrower head

and longer antennal segment IV than does E. ( E .) hoerneri, these differences are

indiscrete and reliable separation requires application of the discriminant function

in the key to the viviparous apterae [couplets 27 or 28, see 26].

Synonyms. —Essigella claremontiana Hottes, NEW SYNONYM: holotype, vi-

vip. apt., on slide with 5 other apt., holotype shown by arrow (11 o’clock position);

data: CALIFORNIA. LOS ANGELES Co.: Claremont, 14 Feb 1909, Pinus ra-

diata. Essigella claremontiana holotype deposited in the NMNH.

Essigella cocheta Hottes, NEW SYNONYM: holotype, vivip. apt., on slide with

9 other apt. (including the holotype of E. monelli), E. cocheta holotype shown by

circle (7 o’clock position); data: CALIFORNIA. MENDOCINO Co.: Fort Bragg,

8 May 1936, E.O.E[ssig]., Pinus “ tuberculata ” [= P. muricata]. Essigella cocheta

holotype is deposited in the Essig Museum of Entomology, University of Cali¬

fornia at Berkeley, Berkeley, California.

Essigella monelli Hottes, NEW SYNONYM: holotype, vivip. apt., on same

slide as holotype of E. cocheta (see above), E. monelli holotype shown by circle

(12 o’clock position). Essigella monelli holotype data and depository same as E.

cocheta, above.

Essigella pineti Hottes, NEW SYNONYM: holotype vivip. alat., on slide with

fundatrix of E. (L.) fusca voegtlini; data: CALIFORNIA. MARIPOSA Co.: Yo-

semite, 1218 m (4000 ft), 17 May 1938, E.O.E.[ssig]., Pinus ponderosa. Essigella

pineti holotype is deposited in the Essig Museum of Entomology, University of

California at Berkeley, Berkeley, California.

Essigella swaini Hottes, NEW SYNONYM: holotype, vivip. alat., on slide with

6 other specimens, holotype shown by circle (12 o’clock position); data: CALI¬

FORNIA. LAKE Co.: Kelseyville, 12 Apr 1936, P. Schulthess, Pinus sabiniana.

Essigella swaini holotype is deposited in the Essig Museum of Entomology, Uni¬

versity of California at Berkeley, Berkeley, California.

Range. — Southern British Columbia and Alberta, throughout the western U.S.

(exclusive of Alaska), to southern Mexico (Fig. 8); extensive sampling (Sorensen

1983) has most commonly collected it west of the Cascade-Sierra Nevada ranges

and through Arizona and New Mexico. One confirmed record from Miami, Flor¬

ida suggests it may occur in the Caribbean and have a Pan-Mexican distribution.

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Vol. 70(1)

Figure 8. Distribution of E. (E.) californica [dots (JTS samples), squares (nonJTS samples)], su-

perimposd over an amalgamation of the ranges of its hosts. Collections (not shown) also exist in

southern Florida, central Mexico, France and Spain.

Recently (Turpeau & Remaudiere 1990), I have identified it as having been

introduced into France, in Pinus radiata plantations; since then, it has also been

found in Spain (Seco Fernandez & Mier Durante 1992).

Hosts. —Pinus and Pseudotsuga. Frequently found on: Pinus albicaulis Engel-

mann, P. monticola, P. flexilis, P. leiophylla, P. ponderosa, P. ponderosa var.

arizonica, P. jeffreyi, P. engelmannii, P. sabiniana, P. coulteri, P. torreyana Parry,

P. radiata, P. attenuata, P. muricata\ infrequently found on: Pinus strobiformis,

P. Iambertiana, P. contorta latifolia Engelmann ex S. Watson, P. washoensis Mason

& Stockwell, Pseudotsuga menziesii (Mirbel) Franco, Pseudotsuga macrocarpa

(Vasey) Mayr; not found on: Pinus cembroides Zuccagni, P. edulis Engelmann, P.

1994

SORENSEN: A REVISION OF ESSIGELLA

monophylla, P. quadrifolia, P. balfouriana Greville & Balfour, P. aristata Engel-

mann, P. contorta contorta, P. contorta murrayana, P. contorta bolanderi (Sor¬

ensen 1983). During a recent introduction in France, Turpeau & Remaudiere

(1990) report P. rigida, P. strobus, P. taeda, P. virginiana and P. griffithi McClelland

as additional hosts.

Essigella (E.) californica is frequently abundant on nonnative pines in the central

valley of California, and also on native pines, especially subsection Sabinianae,

in the surrounding foothills and in southern California. Although it is quite po-

lyphagous within Pinus, it is notably absent on piny on pines [see discussion of

E. ( E .) hoerneri ]. It occasionally feeds on Pseudotsuga, but apparently not in the

presence of E. (E.) wilsoni. Although E. (E.) calif ornica may occur on hosts that

are occupied by other, more restricted Essigella species, it is generally less nu¬

merous (i.e., relative abundance on an individual tree) on such hosts than are the

species that are restricted to that niche; this is especially true when both occur on

an individual tree.

Note that with reference to “Sp. A” [= E. (. E .) calif ornica ], Sorensen (1987a:

255, lines 27, 28) mentioned Pseudotsuga as a “(secondary host capture)”; this

unfortunate wording refers to opportunistic capture of a host species as a primary

host, not a secondary (i.e., summer) host in the sense of the life cycle of the

aphidines.

Discussion. — This species, together with E. ( E .) hoerneri, forms the E. ( E .)

calif ornica complex. Essigella (E.) calif ornica is the commonest Essigella in the

western Nearctic and appears to be the species [followed closely by E. (E.) hoerneri]

that is most prone to produce alates, as determined by their frequency among

and within collection samples. This species is operationally defined and may

actually represent a series of sibling entities on different host groups; however, I

am comfortable with considering it to be a single taxon, because the range of its

morphological variance does not appear to significantly exceed that shown by

other, less polyphagous Essigella species. Further taxonomic division, beyond the

current operational level, seems unwarranted unless biological and genetic anal¬

yses are carried out.

Essigella (E.) calif ornica and E. (E.) hoerneri share several nonexclusive apo-

morphies, although I have no doubt that they form a monophyletic group: re¬

duction of the dorsal (major + minor) setae to six [shared with E. (E.) pini] and

the marginal setae to two [with E. (E.) pini, E. (E.) wilsoni and E. ( E .) alyeska]

on abdominal terga III-IV; reduction of the ventral abdominal sclerites on seg¬

ments XII-IV to small, irregular plates [with E. (E.) wilsoni and, in part, E. ( E .)

alyeska, E. (L.) fusca, E. (L.) hillerislambersi and (rarely) E. (E.) pini]; and the

reduction of the mesonotal muscle attachment plates on the latter stadia apterae

nymphs to noninvasive [with E. ( E .) wilsoni, E. ( E .) alyeska, and (very rarely)

E. ( E .) pini].

I have analyzed character variation among and within populations of the E.

( E.) calif ornica complex, in comparison to the E. ( L.) fusca and E. (E.) knowltoni

complexes, using principal component analyses (unpublished data). In those anal¬

yses, the body setal lengths of the former generally loaded uniformly and heavily

on the second principal component vector, with the first vector representing

general-size. The extent of that setal loading was generally much more uniform

for the E. ( E .) calif ornica complex, than it was for these other complexes, indicating

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Vol. 70(1)

that setal lengths vary more, in unison, in the E. (E.) californica complex than in

either of the others. In other analyses (unpublished data), when only E. (E.)

calif ornica and E. (E.) hoerneri were subjected to principal component analysis,

where general-size was again represented by vector 1, they diverged on combi¬

nations of vectors 2 versus 3. The loadings of those vectors indicated that their

separation was chiefly on the basis of body widths and stylet length. In contrast,

Hottes (1957: 109, key couplet 11) used 0.030 mm as a threshold value for the

length of the dorsal setae on the metatibia (his “hairs on the mid region of outer

margin of metathoracic tibiae”) to separate his E. “ calif ornica” and E. “ hoerneri ”;

clearly Hottes’ approach was erroneous.

Essigella (E.) calif ornica and E. ( E .) hoerneri show extreme variation of the

length of the setae on the frons and dorsal setae on the metatibiae. This population

attribute could be considered synapomorphic, as a mutation that allows greater

phenotypic plasticity of setal length in response to environmental conditions, but

the mechanism of expression is not understood. Essigella (E.) wilsoni also shows

a similar tendency, but to a lesser degree; the number of incidences of extreme

setal length reduction (i.e. , < 0.3 x tibial diameter) is much less in it.

Other variation shared by both E. {E.) calif ornica and E. ( E .) hoerneri entails

the relative length of the metatibiae on adult viviparous apterae. On occasion,

aberrant individual viviparous apterae retain the relatively shorter metatibiae that

is characteristic of the ultimate stadium of their nymph (i.e., the holotype of E.

“cocheta ”). This trait also occurs in other Essigella species, but it seems to be

less frequently expressed than in the E. (E.) calif ornica complex. I suspect that

such aberrantly short tibiae result from the failure of a regulatory gene that controls

physiognomic transitions between nymphal versus adult (or alate versus aptera)

allometries.

With the exception of E. ( E.) pini, E. ( E .) californica has caused the greatest

confusion in the genus. Hottes did not have adequate samples to reflect its vari¬

ability, and used poor preparatory techniques. Among his synonyms, E. “monelli ”

and E. “ cocheta ” were stated to lack distinctly bifid tarsal claws, but their types

actually have them; excessive clearing in potassium hydroxide obscures this char¬

acter when viewed through only low power magnification. Other synonyms, E.

“ claremontiana” and E. “ swainif were previously separated on the basis of setal

lengths, which vary continuously. In fact, based upon setal length, Hottes (1957:

85) believed that the series from which Essig originally described “Lachnus cal-

ifornicus ” must have had specimens of E. “ essigi ” in it [see discussion of that

species], Wilson’s (1919: 1) (re)description of “Essigella californica (Essig),” from

material on Pseudotsuga “ douglassi ” [= P. menziesii], “Pinus ponderosaT ’ and

specimens sent to him by Essig, most probably incorporates species other than

E. ( E.) californica ; if so, E. ( E .) wilsoni and E. ( L.) fusca might presumably be

involved, but I cannot determine this.

Ironically, even Essig (1909) had some trouble recognizing the different morphs

when originally describing E. ( E .) californica. For example, Essig’s illustration of

an aptera of the species (Essig 1909: fig. 2a-b, 2d) clearly shows the legs with

sensoria, which he mentions in the description, but the description is labeled

“Apterous Vivivarous Female”; these are pseudorhinaria of the ovipara morph,

however.

Coded References to This Taxon.—Essigella (E.) californica has been referred

1994

SORENSEN: A REVISION OF ESSIGELLA

to previously by: the coding “Sp. A” (Sorensen 1983, 1987a, 1992b) and “CALF”

(Sorensen 1983), and by the name E. californica in Sorensen (1983).

Etymology and Common Name.— Essig named this species for California, the

state in which its original collection occurred, and where it is most commonly

encountered (e.g., Fig. 8). Common name: the Californian pine needle aphid;

although Essig (1936: 229), Doane et al. (1936: 360), Palmer (1952: 14), and

Furniss & Carolin (1977: 99) refer to this species as the “Monterey Pine Aphid,”

the common name indicated here is more appropriate and less confusing because

Pinus radiata, Monterey pine, as a niche is occupied much more representatively

by E. (E.) essigi, whereas E. (E.) californica is quite polyphagous within Pinus.

Material Examined. — ARIZONA. COCHISE Co.: Amer. Mus. Nat. Hist. Southwest Research

Station, Chiricahua Mts, 1700 m, 16 Sep 1978, JTS 78143, P. engelmannii, (apt.); Carr Canyon Rd,

Huachuca Mts, 2070 m, 17 Sep 1978, JTS 78155, P. engelmannii, (apt.); Miller Canyon Rd, Huachuca

Mts, 1700 m, 17 Sep 1978, JTS 78152, P. leiophylla, (apt.); nr Steward Camp, Chiricahua Mts, 1530

m, 16 Sep 1978, JTS 78142, P. leiophylla, (apt., alat.). COCONINO Co.: 9 km W of Williams on hwy

66, 2070 m, 9 Sep 1978, JTS 7815, P. ponderosa, (apt.). GILA Co.: 16 km E of Kohles Ranch on hwy

260, 1700 m, 9 Sep 1978, JTS 78111, P. ponderosa, (apt.). GRAHAM Co.: SW of Stafford on hwy

366, 1830 m, 15 Sep 1978, JTS 78136, P. leiophylla, (apt.); same but 1980 m, JTS 78137, P. ponderosa

var. arizonica, (apt.). MARICOPA Co.: Phoenix, 13 Jan 1972, D. Carver, P. canariensis, (apt.); Sun

City, 27 Jan 1972, D. Carver, P. taeda, (apt.). NA VAJO Co.: Mogollon Rim Rd, 8 km SW of Showlow,

2070 m, 10 Sep 1978, JTS 78113, P. ponderosa, (apt.). PIMA Co.: Bear Canyon Picnic Area, Santa

Catalina Mts, 1830 m, 18 Sep 1978, JTS 78157, P. leiophylla, (apt., alat.); same but JTS 78160, P.

ponderosa var. arizonica, (apt.). COUNTY UNCERTAIN: Sitgreaves Natl Forest, 19 Jun 1969, D. T.

Jennings, P. ponderosa, (apt.). CALIFORNIA. ALAMEDA Co.: Berkeley, 23 Apr 1947, E. O. Essig,

P. radiata, (apt., alat.); same but 10 Nov 1935, (apt.); same but 28 Oct 1952, trap pan, (alat.). ALPINE

Co.: E. side of Ebbett’s Pass on hwy 4, 3 km E of summit, 2440 m, 17 Jul 1977, JTS 77G41, P.

monticola, (apt.); same but W side, 5 km W of summit, 2500 m, JTS 7 7 G4 3, P. jeffreyi, (gcpi). AMADOR

Co.: 13 km N of Plymouth, 29 May 1977, J. T. Sorensen, P. sabiniana, (apt., alat.). BUTTE Co.:

Chico, 27 Oct 1949, H. T. Osborn, CDFA 40-K-5, P. yunnanensis Franchet [?], (apt., alat.); Feather

River Cyn, 22 km NE of jet of hwy 70 & Cherokee Rd, 26 Jun 1977, JTS 77F14, P. ponderosa, (apt.).

CALAVERAS Co.: 18 km E of Arnold on hwy 4, 1680 m, 17 Jul 1977, JTS 77G46, P. ponderosa,

(apt.); 2 km NE of Murphys on hwy 4, 670 m, 17 Jul 1977, JTS 77G47, P. ponderosa, (apt.); 7 km

NE of Angel’s Camp on hwy 4, 460 m, 17 Jul 1977, JTS 77G48, P. sabiniana, (apt., alat.). COLUSA

Co.: W of William on hwy 20, 18 Apr 1979, T. Kono & P. Crane, CDFA 79D19-35, P. sabiniana,

(apt.). CONTRA COSTA Co.: Mt Diablo, 23 Apr 1939, E. O. Essig, P. sabiniana, (alat.); Orinda, 29

Sep 1961, E. I. Schlinger, EIS 61-9-30b, Pinus sp., (apt., alat.). DEL NORTE Co.: Gasquet, 21 Sep

1966, P. Allen, CDFA 66-116-14, Pseudotsuga menziesii, (alat.). EL DORADO Co.: Blodgett Exper¬

imental Forest (Univ. Calif.), E of Georgetown, 26 Jul 1973, D. J. Voegtlin, DJV 55, P. ponderosa,

(apt., alat.); same but 28/29 May 1977, J. T. Sorensen, P. lambertiana, P. ponderosa, (alat.); George¬

town, 29 May 1977, J. T. Sorensen, P. sabiniana, (apt., alat.); Lake Tahoe, Meek’s Bay, 1980 m, 16

Jul 1977, JTS 77G29, P. jeffreyi, (apt.); Mutton Cyn, 3 Oct 1961, T. Kono, Pinus sp., (alat.); S Fork

of American River, 5 Jul 1973, D. J. Voegtlin, DJV 35, P. sabiniana, (apt.). FRESNO Co.: 22.4 km

(14 mi) W of Coalinga on hwy 145, 25 Apr 1979, D. Taylor, CDFA 79D27-8, P. sabiniana, (apt.,

alat.); Clovis, 7 Apr 1965, Dunnegan, CDFA 65D9-21, P. canariensis, (apt.); Trimmer, Pine Flat

Lake, 13 Aug 1977, JTS 77H8, P. sabiniana, (apt.); jet of hwys 180 & 245, 1620 m, 13 Aug 1977,

JTS 77H9, P. ponderosa, (apt.). HUMBOLT Co.: nr Little River State Beach, 17 km N of Areata on

hwy 101, 4 Jul 1978, JTS 78G3, P. muricata, (apt., alat.). KERN Co.: Caliente-Bodhsh Rd, S of

Bodhsh, 820 m, 20 Sep 1977, JTS 77167, P. sabiniana, (apt.); Heritage Park, 19 Jun 1967, K. Hench,

P. canariensis C. Smith, (apt.); Keene, 760 m, 20 Sep 1977, JTS 77162, P. sabiniana, (apt.); Kemville,

22 May 1978, C. F. & C. S. Smith, CFS 78-76, Pinus sp., (apt., alat.); Lebec, 25 Mar 1958, E. I.

Schlinger, EIS 58-3-259, P. sabiniana, (apt.); Tehachapi Mtn Park, S of Tehachapi, 1980 m, 19 Sep

1977, JTS 77160, P. ponderosa, (apt.); same but JTS 77161, P. jeffreyi, (apt.); Tiger Flat Rd, N of hwy

155, nr Alta Sierra, 1890 m, 20 Sep 1977, JTS 77164, P. lambertiana, (ovip.); same but JTS 77166,

P. jeffreyi, (apt.). LAKE Co.: 10 km S of Lake Pillsbury, Elk Mt Rd, 930 m, 24 Jul 1977, JTS 77G57,

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

P. ponderosa, (apt., alat.); same but 5 km S, 640 m, JTS 77G56, P. jejfreyi, (apt.); 21 km N of Upper

Lake, Elk Mt Rd, 1030 m, 24 Jul 1977, JTS 77G60, P. attenuata, (alat.); Kelseyville, 12 Apr 1936,

P. Schulthess, P. sabiniana, (apt.); same but 15 Jul 1935, E. Doybell, (alat.); W of Lake Pillsbury, Eel

River Rd, 340 m, 24 Jul 1977, JTS 77G54, P. sabiniana, (apt., alat.). LASSEN Co.: 7 km SW of

Susanville on hwy 36, 1460 m, 4 Jul 1977, JTS 77G13, P. jejfreyi, (apt., alat.); Lassen Natl Park,

summit area, 2440 m, 10 Jul 1977, JTS 77G18, P. monticola, (apt.); hwy 89 (nr Lassen Natl Park),

6 km N of jet with hwy 36, 2013 m, 10 Jul 1977, JTS 77G20, P. monticola,(apt.). LOS ANGELES

Co.: (lectotype) Claremont, 14/18 Feb 1909, E. O. Essig, P. rndiata, (apt., alat.); Lake Hughes, 22 May

1959, E. I. Schlinger, EIS 59-5-23k, P. ponderosa, (alat.); same but 2 km NE on hwy N2, 1000 m, 18

Sep 1977, JTS 77152, P. sabiniana, (apt.); 3 km SE of Big Pines on hwy 2, E of Blue Ridge Summit,

2200 m, 17 Sep 1977, JTS 77149, P. jejfreyi, (alat.); Azuza, 4 Nov 1969, McHom & Weber, CDFA

69K7-8, P. canariensis, (apt.); Camp Baldy, 5 Dec 1956, J. MacSwain, “on fir,” (apt., alat.); hwy 2,

7 km NE of jet with Mt Wilson Rd, San Gabriel Mts, 1530 m, 18 Sep 1977, JTS 77151, P. coulteri,

(apt.). MARIN Co.: San Rafael, 18 May 1967, C. Schmid, P. radiata, (apt.). MARIPOSA Co.: Feliciana

Mt, 25 Jul 1946, H. Chandler, P. “ tuberculata ” [= muricata!], (apt.); Yosemite Natl Park, Camp

Foresta, 1340 m, 30 Jul 1977, JTS 77G64, P. ponderosa, (apt., alat.); same but JTS 77G65, P.

lambertiana, (apt.). MENDOCINO Co.: 10 km W of Laytonville, Branscomb Rd, 580 m, 24 Jul 1977,

JTS 77G53, P. ponderosa, (apt.); Albion-Little River Rd, 5 km E of hwy 1, 210 m, 23 Jul 1977, JTS

77G52, P. muricata, (apt., alat.); Fish Rock Rd, 7 km E of Anchor Bay, 23 Jul 1977, JTS 77G51, P.

muricata, (apt.); Fort Bragg, 8 May 1936, E. O. Essig, P. “ tuberculata ” [= muricata!], (apt.). MODOC

Co.: 1 km W of Adin Pass on hwy 299, 21 Jul 1978, JTS 78G120, P. ponderosa, (apt.); E side of

Cedar Pass, 29 km E of Alturas, 1890 m, 3 Jul 1977, JTS 77G12, P. ponderosa, (apt.). MONO Co.:

Deadman Summit on hwy 395, nr Crestview, 2440 m, 31 Jul 1977, JTS 77G72, P. jejfreyi, (apt.);

Saddlebag Lake, 3050 m, 31 Jul 1977, JTS 77G69, P. albicaulis, (apt., fund.). MONTEREY Co.: Cone

Mt, 9 Aug 1962, E. I. Schlinger, EIS 62-8-9a, Pinus sp., (apt.); Cone Peak Rd, 2 km N of jet with

Nacimento-Fergusson Rd, Los Padres Natl Forest, 910 m, 4 Sep 1977, JTS 7719, P. coulteri, (apt.);

Lockwood-San Ardo Rd, 13 km SW of jet with Paris Valley Rd, 550 m, 4 Sep 1977, JTS 7717, P.

attenuata, (apt.); same but JTS 7718, P. sabiniana, (apt.); Monterey, 16 Feb 1979, T. Kono, CDFA

79B20-10-3, P. radiata, (apt.); same but 18 Jun 1973, D. J. Voegtlin, DJV 24, P. radiata, (apt., alat.).

NAPA Co.: 16 km NE of Angwin, jet of Howell Mt Rd & Pope Canyon Rd, 4 Feb 1978, JTS 79B1,

P. sabiniana, (apt.). ORANGE Co.: Anaheim, 9 Feb 1965, J. Seapy, CDFA 65B15-26-2, P. radiata,

(apt.); above Santiago Peak Rd, 10 km N of jet with hwy 74, Cleveland Natl Forest, 1220 m, 10 Sep

1977, JTS 77122, P. coulteri, (apt.); same but JTS 77123, P. attenuata, (apt.). PLACER Co.: 5 km SW

of Whitmore on hwy 80, 1430 m, 25 Jun 1977, JTS 77F1, P. ponderosa, (apt.); 6 km W of Dutch

Flat on hwy 80, 2 Aug 1978, JTS 78H2, P. attenuata, (apt.); same but 27 Aug 1978, JTS 78H160,

(apt.). PLUMAS Co.: 13 km E of Chester on hwy 36, 1520 m, 4 Jul 1977, JTS 77G15, P. jejfreyi,

(apt., alat.); hwy 36, 6 k W of jet with hwy 89, 1460 m, 10 Jul 1977, JTS 77G22, P. lambertiana,

(apt.); same but JTS 77G25, P. jejfreyi, (apt.); Jackson Creek Cmpgd, Plumas Natl Forest, 2 km SE

of Cromberg on hwy 70/89, 1280 m, 26 Jun 1977, JTS 77F12, P. ponderosa, (apt.); Keddie, 18 Oct

1966, Swanson, CDFA 66J24-27, Pseudotsuga menziesii, (apt.). RIVERSIDE Co.: Idyllwild, 1 Jun

1940, C. Michner, P. ponderosa, (apt., alat.); Keen Camp Summit on hwy 74, 3 km N of Mountain

Center, San Bernardino Natl Forest, 1500 m, 9 Sep 1977, JTS 77120, P. coulteri, (apt.); Riverside, 28

Nov 1961, C. Lagace, EIS 61-2-28a, P. canariensis, (apt., alat.); same but 9 Mar 1960, E. I. Schlinger,

EIS 60-3-9a, P. canariensis, (apt., alat.). SACRAMENTO Co.: Wm. Land Park, Sacramento, 26 Aug

1961, T. Kono, Pinus sp., (apt., alat.). SAN BENITO Co.: Clear Creek Rd, 10 km SE of jet with

Coalinga Rd, 1000 m, 3 Sep 1977, JTS 7714, P. coulteri, (apt.); same but 14 km SE of that jet, 1370

m, JTS 7715, (apt., alat.); same but Clear Creek Recreation Area entrance, 2600 m, JTS 7716, P.

sabiniana, (apt.); Coalinga Rd, 2 km SE of jet with hwy 25, 550 m, 3 Sep 1977, JTS 7713, P. sabiniana,

(apt.); Gloria-Bickmore Rd, 14 km W of jet with hwy 25, 580 m, 3 Sep 1977, JTS 7711, P. sabiniana,

(apt.); same but JTS 7712, P. coulteri, (apt.); Pinnacles Natl Monument, 24 Apr 1948, J. MacSwain,

Pinus sp., (apt.). SAN BERNARDINO Co.: 7 km W of Barton Rat on hwy 38, 1950 m, 16 Sep 1977,

JTS 77136, P. coulteri, (apt., alat.); San Bernardino Natl Forest, Keller Peak Cmpgd, 2200 m, 17 Sep

1977, JTS 77142, P. attenuata, (apt.); same but Dogwood, 28 Aug 1972, D. J. Voegtlin, DJV 72, P.

ponderosa, (alat.); same but Running Springs, 4 Aug 1973, DJV 77, P. coulteri, (alat.); same but Snow

Valley, 28 Aug 1972, DJV 69, P. jejfreyi, (alat.); Redlands, 22 Dec 1978, CDFA 78L26-28, P. radiata,

(apt.). SAN DIEGO Co.: 2 km E of Mt Palomar on hwy S6, 1650 m, 11 Sep 1977, JTS 77128, P.

attenuata, (apt.); Mt Palomar Rd (hwy S6), 5 km S of Mt Palomar, 1370 m, 11 Sep 1977, JTS 77126,

Pseudotsuga macrocarpa, (apt.); 5 km S of Julian, Harrison Springs Rd, 1460 m, 12 Sep 1977, JTS

1994

SORENSEN: A REVISION OF ESSIGELLA

77129, P. coulteri, (apt.); La Jolla, Univ. Calif, campus, 11 Sep 1977, JTS 77125, P. torreyana, (apt.,

alat.); San Diego, 10 May 1967, R. Roberson, CDFA 67E15-68, P. radiata, (apt.); same but 29 Jun

1961, O. Beck, CDFA 61F29-53, (apt., alat.); same but 11 Dec 1957, W. Radcliffe, P. canariensis,

(apt., alat.); Torrey Pines State Reserve, 10 Sep 1977, JTS 77124, P. torreyana, (apt.); Valley Center,

18 Apr 1975, G. Gordun, CDFA 75D24-34, Pinus sp., (apt.). SAN FRANCISCO Co.: San Francisco,

28 Apr 1967, M. Stufflebeam, CDFA 67E1-10, P. radiata, (apt., alat.). SAN LUIS OBISPO Co.: 2

km E of Santa Margarita on hwy 58, 300 m, 5 Sep 1977, JTS 77113, P. sabiniana, (apt.); Cuesta Ridge

Botanical Area, nr La Cuesta Summit on hwy 101, N of San Luis Obispo, 730 m, 5 Sep 1977, JTS

77114, P. coulteri, (apt., alat.); Ragged Point, 21 Jul 1973, D. J. Voegtlin, DJV 56, P. radiata, (alat.).

SANTA BARBARA Co.: Happy Canyon Rd, 16 km NE of jet with hwy 154, Los Padres Natl Forest,

370 m, 6 Sept 1977, JTS 77116, P. sabiniana, (apt., alat.); Purissima Hills, 10 km N of jet of hwys 1

& 246, 6 Sept 1977, JTS 77115, P. muricata, (apt., alat.); San Marcos Pass, 740 m, 14 Apr 1960, E.

I. Schlinger & J. Hall, EIS 60-4-15c, P. “ monticola’' [?], (apt., alat.); Santa Barbara, 1 May 1939, G.

Woodham, Pinus sp., (apt., alat.); Santa Cruz Island, Prisoner’s Harbor, 25 Sep 1978, JTS 78164, P.

muricata, (apt.); Santa Ynez, 23 Apr 1975, B. Jarvis, CDFA 75D24-39, Pinus sp., (apt.); Tequepis

Cyn, 17 May 1957, M. Cravens, CDFA 57E21-14, P. radiata, (apt.). SANTA CLARA Co.: Campbell,

19 Apr 1967, G. Prole, CDFA 67E5-34, Pinus sp., (apt.); Palo Alto, Stanford Univ., 25 Apr 1930,

P.S.B., P. radiata, (apt.); same but 7 Apr 1912, H. Morrison, P. “maritima ” [?], (apt., alat.). SANTA

CRUZ Co.: Santa Cruz, 20 Jul 1966, J. Bauer, CDFA 66G26-3, Pinus sp., (alat.). SHASTA Co.: 24

km (15 mi) E of Redding, nr Bella Vista, 29 Mar 1979, D. Henry, CDFA 79C29-19, P. sabiniana,

(apt.); 16 km S of Castella on hwy 5, 400 m, 2 Jul 1977, JTS 77G1, P. sabiniana, (apt.); 2 km W of

Fall River Mills on hwy 299, 21 Jul 1978, JTS 78G121, P. sabiniana, (apt., alat.); same but JTS

78G123, P. ponderosa, (apt.); 3 km N of hwy 299 on Rock Creek Rd, W of Redding, 300 m, 20 Aug

1977, JTS 77H14, P. attenuata, (apt.); Whiskeytown Lake, 370 m, 20 Aug 1977, JTS 77H15, P.

attenuata, (apt.); same but JTS 77H16, P. sabiniana, (apt., alat.). SISKIYOU Co.: Edson Creek access

Rd, Shasta Natl Forest, 8 km W of Bartel on hwy 89, 1160 m, 3 Jul 1977, JTS 77G10, P. jeffreyi,

(apt., alat.); Mt Shasta Ski Bowl Rd, 2450 m, 2 Jul 1977, J. T. Sorensen & D. J. Voegtlin, JTS 77G8,

P. lambertiana, (apt.); same but JTS 77G6, P. ponderosa, (apt., alat.); same but JTS 77G4, P. albicaulis,

(apt., fund.); Snowman Hill Summit on hwy 89, 8 km E of jet with hwy 5, 1360 m, 2 Jul 1977, JTS

77G2, P. ponderosa, (apt., alat.). SOLANO Co.: Green Valley, 29 Oct 1939, N of Frazier, (alat.).

SONOMA Co.: hwy 101, at Sonoma-Mendocino Co. line, 3 Jul 1978, JTS 78G1, P. sabiniana, (apt.,

alat.). TEHAMA Co.: 29 km E of Dales on hwy 36, 910 m, 10 Jul 1977, JTS 77G27, P. sabiniana,

(apt., alat.); same but 970 m, JTS 77G28, P. ponderosa, (apt., alat.); Lanes Valley Rd, nr jet with hwy

36, 490 m, 4 Jul 1977, JTS 77G17, P. sabiniana, (apt.). TRINITY Co.: Big Flat, 1 Jun 1978, C. F.

Smith, P. sabiniana, (apt.); Buckhom Summit on hwy 299, W of Tower House, 980 m, 20 Aug 1977,

JTS 77H17, P. ponderosa, (apt., alat.); Weaverville, 550 m, 20 Aug 1977, JTS 77H20, P. sabiniana,

(apt., alat.); same but JTS 77H21, P. ponderosa, (apt., alat.). TULARE Co.: E of Big Meadows Cmpgd,

Sierra Natl Forest, 2320 m, 13 Aug 1977, JTS 77H13, P. jeffreyi, (apt.); same but JTS 77H12, P.

monticola, (apt.); Visalia, 9 Apr 1971, J. Gilley, CDFA 71D12-11, Pinus sp., (apt., alat.). TUOLUMNE

Co.: 2 km E of Groveville on hwy 120, 910 m, 30 Jul 1977, JTS 77G63, P. ponderosa, (apt., alat.);

7 km W of Big Oak Flat on hwy 120, 550 m, 30 Jul 1977, JTS 77G61, P. sabiniana, (apt.); Kennedy

Meadows, 12 Jul 1951, W. Lange, P. ponderosa, (alat.); Mocassin, 14 Jun 1973, D. J. Voegtlin, DJV

37, P. sabiniana, (apt., alat.); Strawberry, 26 Apr 1951, J. MacSwain, Pinus sp., (alat.); Yosemite Natl

Park, 1330 m, 17 May 1938, E. O. Essig, P. ponderosa, (alat.). VENTURA Co.: 4.8 km (3 mi) S of

Pine Mt Summit, 16 May 1961, R. Van den Bosch, RVdB 61 -V-19j, P. sabiniana, (apt., alat.); Mt

Pinos Summit, 2684 m, 18 Sep 1977, JTS 77154, P. flexilis, (apt., ovip., male); Santa Paula, 26 Jun

1911, E. O. Essig (USNM type 16243, P. radiata, (apt., alat.). YOLO Co.: Davis, 1 Mar 1979, R.

Harris, CDFA 79C2-1-2, P. sabiniana, (apt., alat.); Davis, 19 May 1979, T. & C. Kono, CDFA 79E21-

42, P. sabiniana, (apt.). COLORADO. LARIMER Co.: Stove Prairie Hill, nr Bellvue, 16 Jun 1922,

M. A. Palmer, CAES 3118, P. “ murraryana" [= contorta latifoliaP. ], (alat.); Estes Park, 22 Jul 1922,

M. A. Palmer, CAES 3152, P. flexilis, (apt.). SAN JUAN Co.: 20 km N of Purgatory, 3020 m, 8 Aug

1978, JTS 78H47, P. flexilis, (apt.). FLORIDA. DADE Co.: Opa Locka, 29 Feb 1956, C. Shepard &

L. Daigle, Pinus sp., (apt.). IDAHO. BONNER Co.: 6 km E of Colburn on hwy 95, 18 Jul 1978, JTS

78G102, P. monticola, (apt.); 6 km S of Cocolalla on hwy 95, 18 Jul 1978, JTS 78G105, P. ponderosa,

(apt., alat.). CLEAR WATER Co.: 5 km EofOrofino on hwy 12, 18 Jul 1978, JTS 1&G10&, P. ponderosa,

(apt.). MONTANA. CARBON Co.: E side of Beartooth pass on hwy 212, 2780 m, 20 Aug 1978, JTS

78H118, P. albicaulis, (apt., ovip.). FLATHEAD Co.: 5 km W of MacGregor Lake on hwy 2, E of

Happy Inn, 18 Jul 1978, JTS 78G101, P. ponderosa, (apt., alat.); hwy 93, nr Olney, 17 Jul 1978, JTS

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

78G99, P. monticola, (apt.). NEBRASKA. THOMAS Co.: Halsey, 14 Sep 1958, R. Henzlik, (alat.).

NEVADA. CLARK Co.: Charleston Mts, Lee Canyon Ski Area, 2590 m, 4 Aug 1978, JTS 78H16, P.

flexilis, (apt., alat.). WASHOE Co.: Mt Rose Summit Cmpgd, Toiyabe Natl Forest, 2 Aug 1978, JTS

78H8, P. albicaulis, (apt., fund.); same but JTS 78H9, P. monticola, (apt.); Mt Rose, Slide Mountain

Ski Area, 2 Aug 1978, JTS 78H6, P. washoensis, (apt.). NEW MEXICO. BERNALILLO Co.: 2 km

NW of San Antinito on hwy 44, 2290 m, 12 Sep 1978, JTS 78120, P. ponderosa, (apt.). CATRON

Co.: Apache Natl Forest, 11 May 1978, C. F. & C. S. Smith, CFS 78-24, (apt., alat.). OREGON.

BAKER Co.: 11 km W of Unity on hwy 26, 20 Jul 1978, JTS 78G112, P. ponderosa, (apt., alat.).

CLACKAMAS Co.: Timberline Lodge, Mt Hood, 1770 m, 6 Jul 1978, JTS 78G35, P. albicaulis,

(fund.). DESCHUTES Co.: Sisters, 23 May 1968, C. F. Smith & B. Zak, CFS 68-115, P. ponderosa,

(apt.). HARNEY Co.: 20 km N of Bums on hwy 395, 20 Jul 1978, JTS 78G117, P. ponderosa, (apt.,

alat.). JACKSON Co.: 21 km S of Union Creek on hwy 62, 5 Jul 1978, JTS 78G15, P. ponderosa,

(apt., alat.); same but 3 km E, 110 m, JTS 78G18, (apt). JOSEPHINE Co.: O’brien, 4 Jul 1978, JTS

78G9, P. jeffreyi, (apt.). KL AMATH Co.: 16 km S of LaPine on hwy 97, 5 Jul 1978, JTS 78G26, P.

ponderosa, (apt., alat.). LAKE Co.: 28 km N of Lakeview on hwy 395, 20 Jul 1978, JTS 78G119, P.

ponderosa, (apt.). WASCO Co.: 21 km SE of Government Camp on hwy 26, 970 m, 6 Jul 1978, JTS

78G34, P. monticola, (apt.); same but 46 km SE, 670 m, JTS 78G32, P. c. murrayana, (apt., alat.);

jet of Mills Creek & hwy 26, 35 km NW of Madras, 6 Jul 1978, JTS 78G29, P. ponderosa, (apt., alat.).

UTAH. CACHE Co.: Bearlake Summit on hwy 89, 8 km W of Garden City, 2350 m, 24 Aug 1978,

JTS 78H132, P. flexilis, (apt.). DUCHESNE Co.: 19 km NE of Castle Gate on hwy 33, 2770 m, 25

Aug 1978, JTS 78H144, P. flexilis, (apt.); W of Duchesne, 29 Jun 1958, G. F. Knowlton, (alat.). IRON

Co.: 32 km SE of Cedar City on hwy 14, 3020 m, 5 Aug 1978, JTS 78H27, P. flexilis, (apt.). PIUTE

Co.: Marysville Cyn, 11 Jun 1943, G. F. Knowlton, P. ponderosa, (alat.). WASHINGTON. CHELAN

Co.: 8 km SW of Chelan on hwy 97, 12 Jul 1978, JTS 78G68, P. ponderosa, (apt., alat.); Washington

Pass on hwy 20, 1700 m, 12 Jul 1978, JTS 78G75, P. albicaulis, (apt., fund.). CLALLAM Co.: Olympic

Natl Park, Hurricane Ridge, 9 Jul 1978, JTS 78G51, P. monticola, (apt., fund.). GRAYS HARBOR

Co.: 16 km W of Amanda Park on hwy 101, 10 Jul 1978, JTS 78G54, P. monticola, (apt.). KING

Co.: Seattle, 16 Jun/20 Oct 1955, M. Forsell, Pinus sp., (apt.). KITSAP Co.: 8 km S of Hood Canal

bridge on hwy 3, 9 Jul 1978, JTS 78G49, P. monticola, (apt.). OKANOGAN Co.: 17 km NW of

Winthrop on hwy 20, 550 m, 12 Jul 1978, JTS 78G71, P. ponderosa, (apt., alat.). WHITMAN Co.:

Pullman, 26 Sep 1956, F. C. Hottes, P. ponderosa, (alat.). YAKIMA Co.: 16 km W of Naches on hwy

410, 11 Jul 1978, JTS 78G65, P. ponderosa, (apt.); E side of Chinook Pass on hwy 410, 1310 m, 11

Jul 1978, JTS 78G63, P. monticola, (apt.); Union Gap, 22/26 Sep 1952, E. Davies, trap pan, (alat.).

WYOMING. CROOK Co.: 6 km W of Devil’s Tower Jet on hwy 14, 1100 m, 19 Aug 1978, JTS

78H104, P. ponderosa, (apt.). PLATTE Co.: S of Glendo on hwy 25, 1920 m, 17 Aug 1978, JTS

78H94, P. ponderosa, (apt.). TETON Co.: Hoback Jet, 19 km S of Jackson on hwy 89, 1860 m, 23

Aug 1978, JTS 78H128, P. flexilis, (apt., male); nr Togwotee Pass on hwy 287, 2800 m, 23 Aug 1978,

JTS 78H125, P. albicaulis, (apt., fund., ovip.). WASHAKIE Co.: 19 km NE of Tensleep on hwy 16,

2350 m, 19 Aug 1978, JTS 78H107, P. flexilis, (apt.); Tensleep Cyn, Bighorn Mts, 1580 m, 20 Aug

1978, JTS 78H111, P. ponderosa, (apt.). CANADA. BRITISH COLUMBIA: 21 km N of Cache Creek

on hwy 97, 13 Jul 1978, JTS 78G81, P. ponderosa, (apt.); 21 km S of Lytton on hwy 1, 13 Jul 1978,

JTS 78G78, P. ponderosa, (apt.); 5 km N ofSpuzzum on hwy 1, 13 Jul 1978, JTS 78G77, P. monticola,

(apt., male); 7 km S of Canal Flats on hwy 93, 17 Jul 1978, JTS 78G95, P. c. latifolia, (apt.); Fairmont

Hotsprings, hwy 93, 17 Jul 1978, JTS 78G91, P. ponderosa, (apt.). MEXICO. DISTRITO FEDERAL:

Ajusco, 2800 m, 2 Apr 1981, G. Remaudiere, Pinus sp., (apt., alat.). STATE UNCERTAIN: Chapingo,

27 Oct 1980, G. Remaudiere, Pinus sp., (apt., alat.). FRANCE. PROVINCE UNCERTAIN: Rennesle

Rheu, 30 Jun 1989, “R 42,” piege, (alat.); Landemeau Finistere, 6 Sep 1989, E. Turpeau, 16580, “P.

radiatalfl (apt.).

Essigella ( Essigella ) hoerneri Gillette & Palmer, 1924

Essigella hoerneri Gillette & Palmer, 1924: 5, Ann. Entomol. Soc. Am., 17: 5-6.

Essigella gillettei Hottes, 1957: 88, Proc. Biol. Soc. Wash., 70: 88-90. NEW

SYNONYM.

Essigella maculata Hottes, 1957: 93, Proc. Biol. Soc. Wash., 70: 93-95. NEW

SYNONYM.

1994

SORENSEN: A REVISION OF ESSIGELLA

Primary Type. — Lectotype, vivip. apt., on slide with 6 other specimens, lec-

totype in upper right; slide data: “ Essigella hoerneri n. sp., lectotype (vivip. apt.)

(type—others paratypes) C. P. Gillette & M. A. Palmer/U.S. Nat. Mus. No. 41952/

On Pinus edulis, 9-25-21, Owl Canon [sic] Larimer Co., Colo., Coll. J. L. Hoemer,

Colo. Agr. Exp. Sta. Ac. 2894/[on back] lectotype, Essigella hoerneri Gillette &

Palmer, J. T. Sorensen 1981.” Lectotype deposited in the U.S. National Museum

of Natural History, Washington, D.C.

There is confusion concerning the lectotype designation. In the original de¬

scription, Gillette & Palmer (1924: 5-6) list no primary type, but later (Gillette

& Palmer 1931: 841) state “Types in U.S. Nat. Mus., Cat. No. 41952; Paratypes

in collection of Colo. Agr. Exp. Sta.” Palmer (1952:16) again refers to that museum

number under the heading Type. There is a second “type” slide, containing one

ovipara with four other specimens, that also bears the U.S. Nat. Mus. number

41952. Consequently, the slide cannot be identified from that number alone.

Hottes (1957: 92) mentions a lectotype and gives the slide data (as above), but

does not tell the position of the designated individual on the slide. Although there

is a “map” of position of the “type” on the slide, I am uncertain that this represents

the lectotype mentioned by Hottes. Because the “type” individual on that slide

was incomplete, I have designated a different, intact specimen from the slide

(upper right corner, 2 o’clock position) as lectotype.

Viviparous Apterae.— Morphology: Body length: 1.49-2.36 (1.86 ± 0.22) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) not exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim greater than 0.5 x diameter of rhinarium; distal face of rhinarial

rim usually oblique to longitudinal axis of antennal segment; rhinarial membrane not conspicuously

protuberant. Length of antennal segment V: 110-148 (130 ± 10) p, processus terminalis: 30-43 (37

± 4) p- IV: 75-120 (101 ± 12) p\ III: 118-238 (175 ± 29) p\ II: 59-88 (70 ± 7) p. Length of longest

setae on frons: 13-88 (48 ± 24) p, tips incrassate to sharp. Head width: 245-329 (291 ± 22) p. Length

of stylets: 714-1130 (860 ± 107) p\ ultimate rostral segment: 58-100 (80 ± 9) p, rostral tip reaching

abdominal terga III-V in dorsal view through slide-mounted specimens. Head + pronotum fused,

total length: 316-459 (385 ± 37) p. THORAX: Meso + metanota fused, total length: 275-439 (371

± 46) p. ABDOMEN: Tergum I free, length: 102-148 (123 ± 13) p\ terga II-VII fused, VIII free.

Maximum distal width of flange on siphunculi: 28-45 (35 ± 5) p; siphunculi flush to truncated conical,

protrusion to 0.7 x maximal distal width. Ventral abdominal sclerites on segments III-IV usually

irregular, subcircular or sublinear when small (length less than 0.6 x metatibial diameter), subquadrate

when large (length greater than 1.0 x metatibial diameter); length: 5-51 (22 ± 11) p, 0.3-1.1 x diameter

of metatibiae. Dorsal (major + minor) setae (see Fig. IF) on abdominal terga III-IV: 6, very rarely

7, tips sharp, in 1 row; marginal setae 2 per segment, each side. Setae on abdominal tergum VIII: 6,

rarely 7, length: 13-60 (31 ± 15) p, tips incrassate to sharp, in 1 row. Cauda rounded; caudal pro¬

tuberance moderately to poorly developed, occasionally absent; length of longest caudal setae: 43-

105 (78 ± 17) p, tips sharp. LEGS: Length of metafemora: 388-857 (596 ± 106) p\ metatibiae: 561-

1275 (908 ± 179) p\ longest dorsal setae on central one-third of metatibiae: 10-113 (38 ± 26) p, 0.1-

2.9 x diameter of metatibiae, tips incrassate to sharp; approximately equal or very gradually increasing

distally, no setal length dimorphism; longest ventral setae on metatibiae: 18-50 (34 ± 10) p, tips

sharp. Length of metabasitarsus: 93-148 (118 ± 15) p\ metadistitarsus: 148-223 (187 ± 18) p. Ratio

of metadistitarsus to metabasitarsus less than 1.9:1, mean 1.58:1. Pigmentation: Color in life: Thorax

gray-green, abdomen lime green, legs yellow-brown. Slide-mounted specimens: Background of body

dorsum usually pale to rarely light brown (to 20 percent pigment density), usually unicolorous, oc¬

casionally abdominal terga dorsomedially dusky to entire abdomen evenly moderate brown (to 50

percent pigment density) in contrast to pale head and thorax. Terga at bases of setae on frons and

dorsal (major + minor) setae on abdomen concolorous with surrounding terga, to rarely subtly darker.

Thoracic muscle attachment plates and dorsal muscle attachment plates of abdomen usually pale,

inconspicuous, to rarely light brown, vaguely evident. Spiracular plates and ventral abdominal sclerites

pale, inconspicuous, to moderate brown, conspicuous. Siphunculi concolorous with surrounding terga.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Cauda, anal, and subgenital plates concolorous with abdominal terga to subtly darker. Antennal

segments Y and IV subtly dusky distally, pale proximally, to entirely dusky, infrequently to moderate

brown; III entirely very pale to subtly dusky on distal one-third, remainder pale; II as pale as proximal

III to subtly darker; I concolorous with frons. Pro-, meso- and metatibiae concolorous, usually evenly

pale, equivalent to thoracic tergum or slightly darker, to subtly dusky on distal and occasionally

proximal tip, rarely entirely dusky. Distitarsi usually dusky on distal one-half, pale proximally, to

entirely dusky with distal tip of tibiae.

Ultimate Stadium Nymphs of Viviparous Apterae. — Slide-mounted specimens: Nonmorphometrics

as described for viviparous apterae except lacking body dorsum pigmentation suite; abdominal terga

membranous with dorsal (major + minor) setae, between muscle attachment plates, arising from

distinct scleroites. Mesonotum lacking 2 sclerotized plates extending from muscle attachment sites to

engulf neighboring setal bases; area surrounding muscle attachment sites membranous.

Viviparous Alatae. - Slide-mounted specimens: Nonmorphometrics as described for viviparous ap¬

terae except lacking body dorsum pigmentation suite; abdominal terga normally membranous, dorsal

setae between muscle attachment plates very rarely arising from distinct scleroites; antennal segments

often as dark as tibiae, except proximal one-fifth of III pale. Antennal segment III with 0-5, IV with

0-3, secondary rhinaria. Epicranial suture strongly developed. Forewing medius with single furcation

arising on proximad one-third of vein; cubital base arising proximad on subcosta with distance between

anal and cubital bases on subcosta relatively small, ca. 20-30 percent or less of anal vein length;

medius, especially cubitus and anal veins usually distinct, except infrequently proximad 10-15 percent

vague. Abdominal terga lacking irregular sclerites that engulf or join muscle attachment plates and

dorsal (major + minor) setal bases or scleroites.

Oviparae. — Slide-mounted specimens: Nonmorphometrics as described for viviparous apterae ex¬

cept abdominal dorsum membranous with irregular transverse sclerites containing dorsal (major +

minor) setae on each tergum; marginal setae usually on separate scleroites; siphuncular cones scler¬

otized, regular, separated from other dorsal sclerotic fields; dorsal abdominal muscle attachment plates

unicolorous. Rarely with abdominal terga II-VI sclerotic/fused, terga VII and VIII free; then dorsal

demarcations of anterad terga evident and siphuncular cones surrounded closely by, sometimes en¬

gulfed by, sclerotic fields. Pseudorhinaria on metatibiae irregular, 11-23.

Males, Fundatrices.— Unknown.

Diagnosis. —Essigella (E.) hoerneri requires the combination of several char¬

acters for identification; individuals usually are pale and may be confused with

other pale Essigella. Essigella (E.) hoerneri can be separated from all Essigella,

except E. (E.) californica and E. (E.) pini by having six (Fig. IF), instead of eight

or more, dorsal (major + minor) setae on abdominal terga III-IV. Diagnostics

for all morphs of E. ( E .) hoerneri that separate it from E. ( E .) pini are the same

as for E. (E.) californica [see that diagnosis].

Essigella (E.) hoerneri and E. (E.) californica are difficult to distinguish. Al¬

though E. ( E .) hoerneri has a longer rostrum, wider head and shorter antennal

segment IV than does E. ( E .) californica, these differences are indiscrete, and

reliable separation requires application of the discriminant function in the key to

the viviparous apterae [couplets 27 or 28, see 26].

Synonyms.—Essigella gillettei Flottes, NEW SYNONYM: holotype, vivip. alat.,

on slide alone; data: COLORADO. LARIMER Co.: Stove Prairie Hill, Bellevue,

16 Jun 1922, M. A. Palmer, P. murrayana [= P. contorta latifolial ]. Essigella

gillettei holotype deposited in the NMNH.

Essigella maculata Hottes, NEW SYNONYM: holotype, vivip. alat., on slide

alone; data: COLORADO. MESA Co.: Grand Junction, 2 Sep 1956, Pinus edulis.

Essigella maculata holotype deposited in the NMNH.

Range. — Great Basin, from the Sierra Nevada to the Rocky Mountains, south

of Idaho and Wyoming to Arizona, New Mexico and southern California; pre¬

sumably into Mexico following its hosts (Fig. 9).

1994

SORENSEN: A REVISION OF ESSIGELLA

Figure 9. Distribution of is. ( E .) hoerneri [dots (JTS samples), squares (nonJTS samples)], super¬

imposed over the range of its hosts, Pinus monophylla [darker shading] and Pinus edulis [lighter

shading (UT, AZ and east)].

Hosts. —Pinus section Parrya, subsection Cembroides: P. edulis Engelmann, P.

monophylla Torrey & Fremont, P. cembroides Zuccagni and P. quadrifolia Par-

latore [see discussion]. Essigella ( E .) hoerneri is the only Essigella regularly on

piny on pines [E. (L .) fusca has rarely been taken on pinyons, but is considered

nonresident]. References to E. (E.) hoerneri on P. flexilis and P. ponderosa are

probably erroneous, or at least nonresident; although I have not yet seen the slides,

I suspect they represent E. (E .) californica, or in the case of ponderosa pine possibly

E. (. L .) fusca.

Discussion. —Essigella (E.) hoerneri is closely related to E. (E.) californica\ see

the discussion of that species, where most comments apply equally to E. (E.)

hoerneri ]. The long rostrum and styli of E. (E.) hoerneri are autapomorphic;

although, within other Essigella species complexes, some species may have these

features slightly lengthened in comparison to their close relatives, that lengthening

is not in the same class as here. In E. ( E .) hoerneri, this appears to be an adaptation

to feeding on pinyons, whose needles are relatively thick. Their needle thickness

results from a failure to split into the multiple needles (Mirov 1967) that normally

arise from a needle fascicle (e.g., Pinus monophylla). There is an east-west gradient

for stylet length in this aphid, which appears to roughly reflect the needle diameter

of the hosts. The more eastern populations of E. (. E.) hoerneri (Colorado, New

Mexico) have a relatively shorter rostrum, and the rostrum reaches maximal

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

relative length in the populations of the Owens Valley area of California, and

western Nevada. This reflects their host pine geography and needle diameter:

Pinus monophylla, a single-needled pinyon with a large diameter needle, occurs

west of the Nevada-Utah border; whereas P. edulis, a double-needled pinyon with

needles of proportionately less diameter, occurs to the east. The exact species

status of these two pines may be questionable (W. B. Critchfield, personal com¬

munication).

Essigella (E.) hoerneri has apparently split (Fig. 13: node 10) from the E. (E.)

californica lineage to ecologically reinvade Pinus (Strobus ), on subsection Cem-

broides pines. These section Parrya pine niches are unoccupied by other Essigella.

The Archeoessigella species feed monophagously within Pinus (Strobus), but in

section Strobus, subsection Strobi; E. (E.) californica and E. (E.) pini also feed

in that subsection in polyphagy; further, E. (E.) californica occurs on P. albicaulis,

the sole Nearctic representative of Pinus (Strobus) section Strobus, subsection

Cembrae. Interestingly, the other section Parrya subsections are not occupied by

Essigella : subsection Gerardianae is Asian, but the Nearctic subsection Balfour-

ianae probably predates Essigella (see Ecological Corroboration of tl).

Coded References to This Taxon. —Essigella (E.) hoerneri has been referred to

previously by: the coding “Sp. B” (Sorensen 1983, 1987a, 1992b) and “HOER”

in (Sorensen 1983), and by the name E. hoerneri in Sorensen (1983).

Etymology and Common Name.— This species was apparently named after J.

L. Hoerner, who collected the series upon which the original description was based

(Gillette & Palmer 1924: 5). Common name: Hoemer’s pinyon pine needle aphid;

although Palmer (1952: 15) refers to this species as “The Immaculate Pine Needle

Aphid,” the common name indicated here is more appropriate and less confusing

because other Essigella are immaculate, in the sense of lacking “speckles” [see

etymology for E. (E.) pini].

Material Examined.— ARIZONA. APACHE Co.: 5 km W of Eagar on hwy 273, 2140 m, 11 Sep

1978, JTS 78115, P. edulis, (apt.); 6 km N of Lupton on hwy 12 (= 166), 1980 m, 11 Sep 1978, JTS

78116, P. edulis, (apt., alat.). COCHISE Co.: Miller Canyon Rd, Huachuca Mts, 1700 m, 17 Sep 1978,

JTS 78153, P. cembroides, (apt.). COCONINO Co.: 22 km N of Williams on hwy 64, 2070 m, 9 Sep

1978, JTS 7817, P. edulis, (apt.); 32 km S of Grand Canyon Village on hwy 180, 2070 m, 9 Sep 1978,

JTS 7819, P. edulis, (apt.); 8 km W of Grand Canyon Caverns on hwy 60, 1700 m, 9 Sep 1978, JTS

7813, P. edulis, (apt.). CALIFORNIA. INYO Co.: Bristlecone Pine Forest entrance on hwy 168, Inyo

Natl Forest, W of Westgard Pass, 2230 m, 31 Jul 1977, JTS 77G74, P. monophylla, (apt.); jet of Lake

Sabrina Rd & Southern Calif. Edison Plant 2 Rd, nr Bishop, 2130 m, 1 Aug 1977, JTS 77H3, P.

monophylla, (apt., alat.). KERN Co.: Valle Vista Cmpgd, 13 km W of Apache Saddle Ranger Station,

1500 m, 18 Sep 1977, JTS 77156, P. monophylla, (apt.); W side of Walker Pass on hwy 178, 26 km

E of Oyx, 1530 m, 20 Sep 1977, JTS 77163, P. monophylla, (apt., alat.). MONO Co.: Cedar Flat, nr

White Mt, 15 Jul 1961, E. I. Schlinger, EIS 61-7-15h, “Pinon pine,” (apt.); E side of Monitor Pass

on hwy 89, 2070 m, 17 Jul 1977, JTS 77G36, P. monophylla, (apt., alat.); Lee Vining Cmpgd, Inyo

Natl Forest, W of Tioga Pass on hwy 120, 2290 m, 31 Jul 1977, JTS 77G70, P. monophylla, (apt.);

Sherwin Summit, 17 Jul 1972, D. J. Voegtlin, DJV 47, P. monophylla, (apt.); Topaz Lake, 1680 m,

5 Jul 1979, S. Paulaitis, DJV 541, P. monophylla, (apt.). RIVERSIDE Co.: 2 km N of Paradise Valley

on hwy 74, 1500 m, 9 Sep 1977, JTS 77119, P. quadrifolia, (apt.); Alpine Village, 21 km S of Palm

Desert on hwy 74, 1160 m, 9 Sep 1977, JTS 77117, P. monophylla, (apt.); Joshua Tree Natl Monument,

Key’s View, 1530 m, 12 Sep 1977, JTS 77133, P. monophylla, (apt.). SAN BERNARDINO Co.: 16

km W of Barton Flat on hwy 38, 2140 m, 16 Sep 1977, JTS 77140, P. monophylla, (apt.); Pipes Cyn,

NW of Yucca Valley & Pioneer Town, 8 km NW of jet of Pioneertown Rd & Pipes Canyon Rd, 1530

m, 15 Sep 1977, JTS 77134, P. monophylla, (apt., alat.); Sheep Cyn, 2 km NW of Mountain Top Jet

on hwy 138, 1525 m, 17 Sep 1977, JTS 77147, P. monophylla, (apt.); nr Ivanpah, New York Mts,

1994

SORENSEN: A REVISION OF ESSIGELLA

1600 m, 8 Sep 1978, JTS 7812, P. monophylla, (apt.); same but 1700 m, JTS 7811, P. edulis, (apt.).

VENTURA Co.: Cuyama Valley, 22 May 1959, E. I. Schlinger, EIS 59-5-23i, P. “ cembroides ” [?],

(apt., alat.); Lake of the Woods, 10 km W of Tejon Pass, 1556 m, 18 Sep 1977, JTS 77153, P.

monophylla, (apt., alat.). COUNTY UNCERTAIN: Frazier Park, 22 May 1959, E. I. Schlinger, EIS

59-5-23d, P. “ cembroides ” [?], (apt., alat.) (slide is labeled “Los Angeles” Co., but Frazer Park is in

Kern Co.; however, main roads in NW L.A. Co. are less than ~5 km away and Ventura Co. is also

immediately adjacent). COLORADO. CHAFFE Co.: Poncha Springs, 2440 m, 12 Aug 1978, JTS

78FI69, P. edulis, (apt.). LARIMER Co.: (lectotype) Owl Cyn, 25 Sep 1921, C. P. Gillette & J. Hoemer,

CAES 2894, P. edulis, (apt.); (paratype) same but 10 Oct 1921, C. L. Corkins, CAES 3028/USNM

41952, (apt., ovip.); (paratype) same but 6 Nov 1921, J. Hoemer, CAES 3035, (ovip.). MESA Co.:

Grand Junction, 2 Sep 1956, P. edulis, (alat.); same but 3 Oct 1956, F. C. Hottes, (alat.). SAN MIGUEL

Co.: 6 km NE of Placerville on hwy 62, 2320 m, 7 Aug 1978, JTS 78H41, P. edulis, (apt.). COUNTY

UNCERTAIN: Refe, 17 Aug 1956, P. edulis, (apt.). NEVADA. CLARK Co.: Charleston Mts, Lee

Canyon Rd (hwy 52), 2290 m, 4 Aug 1978, JTS 78H14, P. monophylla, (apt.); same but Lee Canyon

Ski Area, 2590 m, JTS 78H18, P. ponderosa, (alat.); W of Las Vegas, 20 Apr 1978, C. F. Smith, CFS

78-56, P. monophylla, (apt., alat.). DOUGLAS Co.: hwy 395, 16 km NW of jet with hwy 3, Pine Nut

Mts, 1650 m, 16 Jul 1977, JTS 77G35, P. monophylla, (apt.). LANDER Co.: Scott Summit on hwy

50, 11 km E of Austin, 2230 m, 26 Aug 1978, JTS 78H158, P. monophylla, (apt., alat.). WASHOE

Co.: Mt Rose, Slide Mountain Ski Area, 2 Aug 1978, JTS 78H6, P. washoensis, (alat.). WHITE PINE

Co.: Leyland Cave Natl Monument, 2074 m, 26 Aug 1978, JTS 78H156, P. monophylla, (apt.); Little

Antelope Summit on hwy 50, 56 km E of Eureka, 2260 m, 26 Aug 1978, JTS 78H157, P. monophylla,

(apt.). NEW MEXICO. BERNALILLO Co.: Crest View, hwy 14, 2280 m, 12 Sep 1978, JTS 78121,

P. edulis, (apt., alat., ovip.). RIO ARRIBA Co.: 8 km S of Tierra Amarilla on hwy 84, 2410 m, 8 Aug

1978, JTS 78H52, P. edulis, (apt., alat.). SANTA FE Co.: 20 km NE of Santa Fe on hwy 475, 2680

m, 10 Aug 1978, JTS 78H57, P. edulis, (apt.). SIERRA Co.: 2 km E of Kingston on hwy 90, 1860

m, 14 Sep 1978, JTS 78131, P. edulis, (apt.). OKLAHOMA. CIMARRON Co.: Kenton, 16 May 1961,

Van Cleave, “Pinon pine,” (apt., alat.). UTAH. DAGGETT Co.: Flaming Gorge Dam, Dutch John,

22 Jun 1978, C. S. Smith, CFS 78-238, “pinyon pine,” (apt., alat.) (slides of this series marked Butch

John and Dutch John, Wyoming). DUCHESNE Co.: Starvation lake, hwy 40, 1800 m, 25 Aug 1978,

JTS 78H140, P. edulis, (apt.). GARFIELD Co.: hwy 20, 5 km W of jet with hwy 89, 2040 m, 6 Aug

1978, JTS 78H32, P. edulis, (apt.). SEVIER Co.: 35 km E of Salina on hwy 70, 2130 m, 6 Aug 1978,

JTS 78H33, P. edulis, (apt., alat.). WASHINGTON Co.: 43 km SW of Cedar City on hwy 15, 1220

m, 5 Aug 1978, JTS 78H22, P. monophylla, (apt.). WAYNE Co.: 2 km NE of La Sal on hwy 46, 2230

m, 6 Aug 1978, JTS 78H36, P. edulis, (apt.).

Essigella (Essigella) wilsoni Hottes, 1957

Essigella wilsoni Hottes, 1957: 106, Proc. Biol. Soc. Wash., 70: 106-108.

Essigella pergandei Hottes, 1957: 100, Proc. Biol. Soc. Wash., 70: 100. NEW

SYNONYM.

Essigella oregonensis Hottes, 1958: 155, Proc. Biol. Soc. Wash., 71: 155-156.

NEW SYNONYM.

Primary Type. — Holotype, vivip. apt., on slide with 6 other specimens, holotype

shown by arrows (12 o’clock position); data: “Douglas Fir, Whitby Isd., Seattle,

Wash., Aug 29, 1955, M. J. Forsell, Coll./Holotype, Essigella wilsoni F.C. Hottes”

(reference to “Whitby Isd.” may be to “Whidbey Island” in Island Co.; Seattle

is in King Co.). Holotype deposited in the Essig Museum of Entomology, Uni¬

versity of California at Berkeley, Berkeley, California.

Viviparous Apterae.—Morphology: Body length: 1.24-2.03 (1.49 ± 0.22) mm. HEAD: Primary

rhinarium on terminal antennal segment (V) exceptionally distad, distance from tip of processus

terminalis to distal face of rhinarial rim less than 0.5, usually 0.3, x diameter of rhinarium; distal face

of rhinarial rim usually perpendicular to longitudinal axis of antennal segment; rhinarial membrane

usually conspicuously protuberant. Length of antennal segment V: 83-113 (101 ± 8) n, processus

terminalis: 20-40 (31 ± 5) ju; IV: 66-95 (82 ± 9) n\ III: 83-183 (133 ± 23) n\ II: 55-80 (66 ± 6) fi.

THE PAN-PACIFIC ENTOMOLOGIST

Vol. 70(1)

Figure 10. Distribution of E. ( E .) wilsoni [dots (JTS samples), squares (nonJTS samples)], super¬

imposed over the range of its hosts, Pseudotsuga menzeisii [darker shading] and Pseudotsuga macro¬

carp a [lighter shading (Santa Barbara Co. and south in CA)].

Length of longest setae on frons: 13-35 (22 ± 6) g, tips incrassate to sharp. Head width: 225-286

(248 ± 14) g. Length of stylets: 408-653 (525 ± 64) /x; ultimate rostral segment: 43-73 (64 ± 7) g,

rostral tip reaching abdominal terga I—II, infrequently III, in dorsal view through slide-mounted

specimens. Head + pronotum fused, total length: 281-428 (332 ± 37) g. THORAX: Meso + metanota

fused, total length: 204-357 (265 ± 35) g. ABDOMEN: Tergum I free, length: 71-153 (99 ± 20) g\

terga II-VII fused, VIII free. Maximum distal width of flange on siphunculi: 31-48 (38 ± 5) g;

siphunculi flush to truncated conical, protruding to 0.5 x maximal distal width. Ventral abdominal

sclerites on segments III-IV usually irregular, subcircular when small (length less than 0.6 x metatibial

diameter), to subquadrate when large (length greater than 1.0 x metatibial diameter); length: 5-53 (27

± 15) m, 0.1-1.3 x diameter of metatibiae. Dorsal (major + minor) setae (see Fig. IE) on abdominal

terga III-IV: usually 8, occasionally 10, very rarely 12, tips sharp, when 8 setae then in 1 row,

infrequently single mesad or lateral-most minor dorsal seta anterad, when 10 or more then in 2

irregular rows, usually with lateral-most minor dorsal seta on each side anterad to its next mesad

neighbor; marginal setae 2 per segment, each side. Setae on abdominal tergum VIII: 6, rarely to 8,

length: 8-28 (12 ± 5) g, tips incrassate to sharp, in 1 row. Cauda rounded; caudal protuberance

1994

SORENSEN: A REVISION OF ESSIGELLA

moderately to poorly developed, infrequently absent; length of longest caudal setae: 45-88 (58 ± 11)

li, tips sharp. LEGS: Length of metafemora: 393-592 (466 ± 52) metatibiae: 561-836 (682 ± 78)

m; longest dorsal setae on central one-third of metatibiae: 10-35 (18 ± 7) u, 0.05-1.5 x diameter of

metatibiae, tips incrassate to sharp; approximately equal or very gradually increasing distally, no setal

length dimorphism; longest ventral setae on metatibiae: 15-38 (24 ± 6) p, tips sharp. Length of

metabasitarsus: 79-110 (94 ± 8) ju; metadistitarsus: 125-180 (155 ± 16) p. Ratio of metadistitarsus

to metabasitarsus less than 1.9:1, mean 1.65:1. Pigmentation: Color in life: Lime green throughout.

Slide-mounted specimens: Background of body dorsum pale (to 10 percent pigment density), unico-

lorous. Terga at bases of setae on frons and dorsal (major + minor) setae on abdomen concolorous

with surrounding terga. Thoracic muscle attachment plates and dorsal muscle attachment plates of

abdomen pale, inconspicuous. Spiracular plates and ventral abdominal sclerites pale to infrequently

light brown. Siphunculi concolorous with surrounding terga. Cauda, anal and subgenital plates pale,

concolorous with abdominal terga, to subtly darker. Antennal segments V and IV dusky, concolorous;

III entirely pale, to distal one-half dusky, remainder pale; II concolorous with proximal III; I con¬

colorous with frons, to subtly darker. Pro-, meso- and metatibiae usually pale, concolorous and

equivalent to body dorsum, infrequently entire tibiae slightly dusky, subtly darker than body dorsum.

Distitarsi entirely pale to subtly dusky on distal one-third.