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FIELDIANA rh"u*"y°"*

APR21*80

Botany

Published by Field Museum of Natural History

New Series, No. 1 September 28, 1979

Donrichardsia, a New Genus of Amblystegiaceae (Musci)

HOWARD CRUM

HERBARIUM

UNIVERSITY OF MICHIGAN

ANN ARBOR, MICH.

LEWIS E. ANDERSON

DEPARTMENT OF BOTANY

DUKE UNIVERSITY

DURHAM, N.C.

Outliers from the ancient flora of the Ozark Mountains are to be

found westward in the highlands of west-central Texas, in an area of

limestone habitats known as the Edwards Plateau. Bryologists

have not made a thorough search of that dry and forbidding area

for whatever rarities might occur there. Eula Whitehouse (1954)

recorded only a few mosses from the plateau. Paul Redfearn (1973,

1976) has collected there in recent years, but has thus far reported

only two records of interest (a new species of Isopterygium and a

variety of Trichostomum crispulum new to the flora of the United

States). His record of Erpodium acrifolium from the vicinity of

Austin, not far to the east, indicates a possibility of Mexican intru-

sion into the flora, perhaps from the San Carlos Mountains of north-

eastern Mexico where the bryophyte flora, though limited, is

decidedly like that of the Ozarks and presumably like that of the

Edwards Plateau.

Whitehouse, in 1932, found a most curious moss in limey spring

waters at Seven Hundred Springs in Edwards County, Texas.

Grout (1933) described it as a new species of Hygroamblystegium.

Because of its remarkably stout costa, he named it H. macroneuron.

Grout admitted that the generic affinities would remain uncertain

Library of Congress Catalog Card No.: 79-53901

ISSN 0015-0746

2 FIELDIANA: BOTANY

until sporophytes were found. It was because of the habit of growth,

on rocks in the water, and the general appearance of the plants that

he saw a resemblance to that genus and more specifically to H.

noterophilum. Both species are decidely calciphilic. They are coarse,

robust plants, often encrusted with lime, and their older portions

often appear bristly because of erosion of all but the stout midribs of

the leaves.

The leaf cells are unlike those of Hygroamblystegium, and noth-

ing about the structure of the plants gives clear indication of a rela-

tionship to that genus, other than the fact that the

pseudoparaphyllia are broadly orbicular. Pseudoparaphyllia are

common in the Amblystegiaceae but not in the Brachytheciaceae

(Ireland, 1971), including the genus Eurhynchium, which has some

aquatic members superficially similar to the Texan plant. It may be

that the only genus of Brachytheciaceae with pseudoparaphyllia is

Conardia, which has a considerable resemblance, in appearance and

habitat, possibly in structure, to the Amblystegiaceae (Robinson,

1965, 1976). Crum (1969) recognized the fact that Hygroamblyste-

gium macroneuron has little in common with other members of that

genus and purely as an interim solution attached it to the genus

Eurhynchium, owing to some similarities in habitat, appearance,

leaf shape, serrulation, and areolation to the Platyhypnidium

segregates from Eurhynchium, such as E. riparioides. The

availability of additional material clearly showing the nature of the

species as well as its considerable variation makes it possible to

assign the species to the Amblystegiaceae and to a new genus,

Donrichardsia, on the basis of positive rather than suggestive

evidence.

The genus is characterized by growth on rocks submerged by

lime-impregnated waters. The plants, coarse and robust, with the

appearance of a Hygroamblystegium or a Hygrohypnum, are made

unique by broad leaves with broad points (bluntly acute to rounded-

obtuse and commonly abruptly cuspidate); margins serrulate in the

upper half and often coarsely dentate near the base of the cuspidate

apex; costa very stout and single, though sometimes laterally spur-

red by thickened streaks of cells similar to those found elsewhere in

the lamina (and sometimes at or near the margins); upper median

cells linear-flexuose and minutely papillose at back owing to the

thickening of upper ends; and apical cells rather noticeably shorter

than the upper median cells.

CRUM & ANDERSON: DONRICHARDSIA 3

oooJ-^

The remarkable nature of this plant was well illustrated by Grout

(1933), although he did not show the considerable variability of the

leaves in shape and structure. Figures 1 and 2, prepared for our

forthcoming Mosses of Eastern North America, give some

characteristics not exhibited in the orginal collection, such as the

excurrency of the costa into a stoutly cuspidate point and the ir-

regular notching or coarse serration at the leaf tip. The papillosity

of the upper leaf cells, not previously given notice in the literature,

is shown in Figure 2. The magnification of Figure 2H is much like

that given by high power of the light microscope.

The Amblystegiaceae, in their evolution, have deployed into the

wet niches of the environment. The aspect of Hygroamblystegium

macroneuron, or Donrichardsia, as we propose to call it, is compati-

ble with that found in such amblystegiaceous genera as Hygrohyp-

num and Hygroamblystegium. The leaf shape and areolation show

resemblances to many members of the family, including Hygrohyp-

num, some species of which also show a costa varying from one leaf

to another. In Donrichardsia the costa is often branched laterally,

sometimes as mere spurs, sometimes conspicuously so. In

Hygrohypnum the costa may be single or forked from near the base

and thus essentially double, but in Calliergon the single costa may

be laterally spurred. The papillae are similar to those of some

species of Cratoneuron. The thickened longitudinal streaks of cells,

whether extending from the costa as spurs, isolated in the lamina, or

near the margins forming more or less distinct borders, hint at a

relationship to Sciaromium, with its distinctive border of differen-

tiated cells, or to Limbella, with a tricostate appearance. The latter

genera seem, however, to be much more closely allied to

Hygroamblystegium, as they have short leaf cells quite unlike those

of Donrichardsia or other genera more clearly related to Hygrohyp-

num.

There is no good reason to look for a relationship in the

Brachytheciaceae. That family has, for the most part, occupied drier

habitat niches than the Amblystegiaceae. Except for some super-

ficial resemblance to the aquatic species of Eurhynchium, as noted

above, and a development of papillae similar to those of Bryhnia,

there are no similarities worthy of consideration, at least in the

absence of sporophytes. And even between the Amblystegiaceae

and the Brachytheciaceae, the shape of the capsule and the color of

the peristome are not always as diagnostic as one might wish. The

Fig. 1. Donrichardsia macroneuron. A, Habit, X2. B, Cells at leaf tip, X238. C,

Cells at leaf base, X 249. D, Leaf outlines, X 33. E, Cross-section of a portion of the

leaf showing the costa and a pluristratose longitudinal streak in the lamina, X 106.

F, Cells at leaf tip, showing shortness of apical cells in comparison with the upper

median cells, X 238. G, Upper median cells of leaf, X 238.

a X

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6 FIELDIANA: BOTANY

presence of pseudoparaphyllia in Donrichardsia supports our argu-

ment for including it in the Amblystegiaceae, although we freely

grant that the evolutionary significance of pseudoparaphyllia is yet

untried.

Whitehouse & McAllister, in their 1954 account of the mosses of

Texas, cited three collections from wet rocks below springs at Seven

Hundred Springs, by Eula Whitehouse (January 1 and November

12, 1932) and Mrs. W.R. Eckert (April 1, 1933). They stated that a

dam constructed in more recent years had flooded the rocks at the

base of the springs. Ann Stoneburner and Robert Wyatt recently

obtained permission to visit the type locality at Seven Hundred

Springs, which is located on a large, privately owned ranch. They

found the species in abundance over boulders and on the sides of

rocks in the springs and apparently flourishing. They found no

evidence of damming or flooding at the site. They made further

searches, without success, at a large number of seemingly similar

calcareous springs there and elsewhere along the South Llano River.

Grout distributed as his North American Musci Pleurocarpi, Sup-

plement no. 43 "co-type" material of Hygroamblystegium macro-

neuron. It was material collected by Whitehouse in November 1931,

10 months after the collection of the holotype. It is thus no more

than a topotype, just as is the later collection by Stoneburner &

Wyatt.

We are glad to name so distinctive a genus for Donald Richards as

a mark of friendship. Now retired from business, Mr. Richards has

long been associated with Field Museum of Natural History.

Though not active in research, he has had an enduring interest in

bryology and an important influence on bryologists. He is, as far as

we know, the only Life Member of the American Bryological and

Lichenological Society.

DONRICHARDSIA new genus

Plantae permagnae, aliquando rigidiusculae, fusco-virides. Caules suberecti, dense

et fastigiate ramosi. Folia oblongo-lanceolata vel oblongo-ovato, late acuta vel ob-

tusa, saepe breviter cuspidata et aliquando abrupte ad apicem dentata; costa

latissima (plus minus 200 /zm lalitudine), saepe irregulariter ramosa, in parte

subapicale terminans vel in mucrone breviter excurrens; cellulae saepe in linearis

longitudinalis pluristratosae. in medio folii anguste oblongae vel lineari-flexuosae.

Caetera ignota.

Plants large and coarse, ca. 14 cm. long, fairly rigid, dull, dark-green to brownish,

in dense to loosely interwoven masses. Stems irregularly to fastigiately branched;

cortical cells small and thick-walled, surrounding 3-6 layers of larger, thick-walled

cells and an inner area of large, thin-walled cells; central strand small and in-

CRUM & ANDERSON: DONRICHARDSIA 7

conspicuous. Pseudoparaphyllia foliose, broad and suborbicular, broadly rounded at

the apex, entire to irregularly serrulate at the apex. Leaves loosely erect and ±

subsecund when dry, erect-spreading when moist, 1.5-1.8 mm. long, oblong-

lanceolate to oblong-ovate, bluntly acute to obtuse or rounded-obtuse and

sometimes abruptly cuspidate; margins plane, serrulate in the upper half, often in

cuspidate leaves abruptly notched or coarsely dentate on 1 or both sides of the cusp;

costa about one-third the width of the leaf base and about 1 60-200 fjim wide below,

only slightly tapered upward, ending somewhat below the apex to excurrent into a

stout cuspidate point, elliptical in section at the leaf middle and composed of

uniformly small cells except for a scattering of larger cells at the center; cells at the

apex ± rhombic, the upper median cells longer and linear-flexuose, minutely

papillose at back because of thickened upper ends, pluristratose in fairly con-

spicuous longitudinal streaks (sometimes as much as five layers thick), sometimes

as spurs from the costa and often at or near the margins; basal cells oblong-linear,

thick-walled, not differentiated in the alar regions. Inflorescences and sporophytes

unknown.

Donrichardsia macroneuron (Grout) new combination. Figures 1, 2.

Hygroamblystegium macroneuron Grout, Bryologist 36: 1. Figs.

1-5. 1933.

Eurhynchium macroneuron (Grout) Crum, Bryologist 72. 242.

1969.

Specimens examined.— Edwards Co., Texas: In springs along the

banks of Llano River, near Junction, Eula Whitehouse, January 1,

1932 (holotype, DUKE; isotype, MICH), November 12, 1932

(distributed as Grout's No. Amer. Musci Pleur. Suppl. no. 43,

DUKE, MICH, CANM, etc.); over boulders and sides of rocks in

springs, limestone cliff on the South Llano River, Seven Hundred

Springs, 20 miles SW of Junction, Ann Stoneburner & R. Wyatt

1485, March 4 1978 (DUKE).

SUMMARY

Donrichardsia is described as a new genus of the

Amblystegiaceae. It is known by its aquatic habitat and oblong-

lanceolate to oblong-ovate, broadly pointed to rounded-obtuse and

often abruptly cuspidate leaves. Leaf margins are serrulate above

the middle and often coarsely dentate at the base of the cusp. The

costa is very stout (about one-third the width of the leaf base), single

but often laterally spurred; the ending varies from being near the

leaf apex to being shortly excurrent. Leaf cells are linear-flexuose,

minutely papillose at the back because of thickened upper ends, and

pluristratose in longitudinal streaks. The genus is based on D.

macroneuron (Grout) n. comb., known from calcareous springs at a

single locality in Edwards County in central Texas. Originally

8 FIELDIANA: BOTANY

described as Hygroamblystegium, the species was later transferred,

by Crum, to Eurhynchium because of superficial resemblances to

the aquatic species sometimes segregated as Platyhypnidium.

REFERENCES

CRUM H.

1969. Nomenclatural notes on North American mosses. Bryologist 72: 240-246.

GROUT, A.J.

1933. Hygroamblystegium macroneuron n. sp. Bryologist 36: 1-2.

IRELAND, R.R.

1971. Moss pseudoparaphyllia. Bryologist 74: 312-330.

REDFEARN, P.L., Jr.

1973. Additions to the moss flora of Texas, and a new species of Isopterygium.

Bryologist 76: 440-442.

1976. A Trichostomum from Texas new to the United States. Bryologist 79: 80-82.

ROBINSON H.

1965. A small collection of bryophytes from Kashmir. Bryologist 68: 313-320.

1976. Conardia, a new moss genus for Hypnum compactum (Hook.) C. Mull.

Phytologia 33: 293-295.

WHITEHOUSE, EULA and F. MCALLISTER.

1954. The mosses of Texas. A catalogue with annotations. Bryologist 57: 63-146.

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UNIVERSITY OF ILLINOIS-URBANA