W. D. W1LLL A Revision of

North American Epigean

Species of Asellus

Crustacea: Isopoda)

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • 1970 NUMBER 49
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SMITHSONIAN CONTRIBUTIONS TO

ZOOLOGY

NUMBER 49

w. D. wiiUam A Revision of

North American Epigean

Species of Asellus

(Crustacea: Isopoda)

SMITHSONIAN INSTITUTION PRESS

CITY OF WASHINGTON

I97O
ABSTRACT

Williams, W. D. A Revision of North American Epigean Species of Asellus (Crustacea: Isopoda). Smithsonian Contributions to Zoology, 49: 1-80,1970.—A taxonomic revision of North America epigean species of Asellus is given based almost

entirely upon a study of male material. Descriptions are given of A. communis Say, A.

brevicauda brevicauda Forbes, A. brevicauda bivittatus Walker, new combination, A.

intermedius Forbes, A. attenuatus Richardson, A. dentadactylus Mackin and Hubricht,

A. montanus Mackin and Hubricht, A. kenki Bowman, A. racovitzai racovitzai, new

species, A. racovitzai australis, new subspecies, A. forbesi, new species, A. obtusus, new

species, A. laticaudatus, new species, A. scrupulosus, new species, A. nodulus, new

species, and A. occidentalis, new species. Asellus militaris Hay is synonymized with A.

intermedius, and A. tomalensis Harford is regarded as a questionable name. It is

suggested that A. aquaticus is absent from the North American continent. A key for

the identification of males is given, and phylogenetic relationships are discussed, taking

into consideration the ideas of Hennig (1950).

Official publication date is handstamped in a limited number of initial copies and is recorded

in the Institution's annual report, Smithsonian Year.

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W. D. Williams A Revision of

North American Epigean

Species of Asellus

(Crustacea: Isopoda)

Introduction

Ten epigean species of Asellus have hitherto been described from North America: A. communis Say, A.

brevicauda Forbes, A. intermedius Forbes, A.

tomalensis Harford, A. militaris Hay, A. attenuatus

Richardson, A. dentadactylus Mackin and Hubricht,

A. montanus Mackin and Hubricht, A. bivittatus

Walker, and A. kenki Bowman. Of these only A.

dentadactylus, A. montanus, and A. kenki have been

described in sufficient detail in their original description to allow reasonable certainty of identification.

The remainder, which includes most of the widespread

species, has been inadequately known. This lack of

knowledge is perhaps excusable because many of the

specific descriptions were prepared before it was realized fully to what extent crustacean taxa should be

described, and before it was appreciated that certain

parts of the anatomy of Asellus, namely the male

genital pleopods, were of particular taxonomic importance. As species of Asellus are frequent members of

the fauna of North American freshwaters, sometimes

forming a considerable proportion of the biomass,

and as there is a continuing need for greater precision

in ecological and pollutional studies dealing with freshwater, the present paper sets out to place our knowledge of the North American surface-living species of

Asellus on a more precise footing.

Since this paper represents a revision and extension

of knowledge of epigean forms, it may be regarded as

complementing the papers of Steeves (1963a,b,

1964a,b, 1965, 1966) which deal with North American

W. D. Williams, Department of Zoology, Monash University, Clayton, Victoria 3168, Australia.

hypogean species on a more or less comprehensive basis.

It is not possible, however, to draw an absolutely distinct line between species occurring in surface waters

and those in underground waters. Thus, three species

which typically occur in hygopean situations have been

reported from surface waters: A. tridentatus (Hungerford) (Leonard and Ponder, 1949; Dexter, 1954);

A. conestogensis Levi (Levi, 1949); and A. stygius

(Packard) (Minckley, 1961). These species are not

discussed in this paper; only those species which

typically occur in surface waters are considered. Such

surface species always have eyes.

During this investigation females were treated only

cursorily, since as far as known they do not possess

specific characters as precise as do males. This paper,

therefore, is based almost entirely upon a study of male

specimens only. Females differ from males principally

in the structure of their first peraeopod and second

pleopod (the first pleopod is always absent), and only

these appendages are mentioned when reference is

made to female material. To avoid confusion, the second pleopod of females is herein referred to as the

"first" pleopod. Females are referred to only when type

material (allotype or paralectotype) is available.

Within males, the most important systematic characters are associated with the genital pleopods, particularly with the tip of the endopodite of the second

pleopod. The terminology here used for the various

structures of the endopodite tip follows Steeves

(1963a). Thus, a maximum of four terminal elements

are associated with the ventral terminal groove: a

mesial process arising from the medial edge of the

ventral groove; a cannula, essentially a tubular prolongation of the ventral groove; a lateral process arising

1
from the lateral edge of the ventral groove; and a

terminal caudal process. To aid interpretation and

comparison on the part of the reader, all drawings

of the endopodite tip in this paper are similarly

oriented and are from the right pleopod.

With regard to the actual examination of the morphology of the endopodite tip, it should be noted mat

variations from the descriptions given in this paper

may appear to occur according to the position of the

appendage when mounted for microscopical examination. It is important that endopodites are in undistorted positions when examined. Furthermore, the

morphology may be altered by clearing or by mounting

in a medium that includes a clearing agent; if the clearing is too severe it may cause contraction and distortion, particularly of the more delicate and unsclerotized parts, e.g., the cannula. The best media, though

temporary, appear to be water or 70 percent alcohol.

For the most part in the present study, material other

than type material was examined after mounting and

clearing in "Euparal" (George Gurr Ltd.). Type

specimens were examined in 70 percent alcohol, and

their various appendages and remains are preserved in

70 percent alcohol in microvials.

All drawings were made with a camera lucida.

Although the most important systematic characters,

that is morphological features associated with the male

second pleopod and particularly with the distal part

of the endopodite, remain relatively constant in males

of different sizes and from different localities, dissimilarities from a type description may occur with regard to both these and other morphological characters.

An indication of the extent of such variation follows

the type description of each species and is based upon

all available male material of the species in question. In

comparisons of unknown material with type descriptions, all segmental appendages from the first antennae

to the uropoda were usually examined.

Apart from that applying to A. communis, in the

type descriptions, details are omitted when these refer

to parts of the body that are similar in morphology to

A. communis (neotype). It should also be noted that:

(1) body length refers to the distance between the

anterior margin of the head and the posterior margin

of the telson, i.e., exclusive of the uropoda; (2) the

length of the second pleopod of males is always regarded as the distance between the proximal end of

the sympod and the distal tip of the endopodite (note

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

that in many species the exopodite extends beyond the

endopodite).

Abbreviations used in this paper referring to the

institutions from which material was borrowed are as

follows:

GLI Great Lakes Institute, Toronto

INHS Illinois Natural History Survey, Urbana

MCZ Museum of Comparative Zoology, Harvard

University

NMC National Museum of Canada, Ottawa

ROM Royal Ontario Museum, Toronto

USNM Smithsonian Institution, United States National

Museum

In the synonymies for each species, no attempt is

made to provide complete references to each name

because of the largely uncritical application of names

that has taken place; only the more important descriptive papers or papers otherwise of some importance

are listed.

Generic and Subgeneric Characters

All species examined during the present study were

clearly covered by the generic diagnosis of Asellus as

given by Birstein (1951, p. 51); the only other freshwater isopods encountered were referable to the genus

Lirceus. However, clear division of North American

species into the subgenera of Asellus reported from

North America—Conasellus Stammer, Mesasellus

Birstein, and Baicaloasellus Stammer—seems not

possible. The simple concept indicated by Birstein

(1951, p. 22) that central and eastern species belong

to the subgenus Conasellus, while western species belong to one or two other subgenera no longer seems

tenable. Thus, comparison of the diagnosis of the subgenus Conasellus as given by Stammer (1932, p. 130)

with the redescriptions and original descriptions of

species given herein and by Steeves (1963a, b, 1964a, b,

1965, 1966) reveals that none of the subgeneric characters is unique for all central and eastern species

other than those which, according to Bresson (1955),

apparently belong to Baicaloasellus. The only character with some constancy is the development of one or

more median processes on the posterior margin of

the propodus of the male first peraeopod. But even

this, while considerably developed in most epigean

species, is definitely absent in several hypogean species.

In view of this situation I, like Bowman (1967), am

inclined in this paper to the ideas of Chappuis (1955,

p. 168) who advised against the creation of subgenera

in the genus Asellus. At the same time, although no
NUMBER 49 5

subgeneric divisions are now attempted, I do not wish follow a further extension of our systematic knowledge

to deny that meaningful species groupings of sub- of epigean forms, especially perhaps those in the west,

generic status are possible for North American species and an integration of this with our knowledge of

of Asellus. Such groupings, however, will need to hypogean species groups.

Key to Males of Known North American Epigean Species of Asellus

(The terms mesial, lateral, and caudal process, ventral groove, and cannula, refer to structures

at the tip of the endopod of the second pleopod.)

1. Palm of propodus of first peraeopod lacking triangular process near midpoint; mesial and

caudal process not developed, but lateral process large, projecting beyond cannula, and

distally recurved (Figures 53D,E, 56) A. occidentalis, new species

Palm of propodus of first peraeopod usually with a triangular process (often large) near midpoint; lateral process either absent, or developed in conjunction with mesial process 2

2. First pleopod usually distinctly longer than second, and distal segment usually subovate, often

curved outward, and with few to several long plumose spines on distal margin 3

First pleopod usually subequal in length to second or distinctly shorter, and distal segment

subovate to subrectangular, without long plumose spines on distal margin 8

3. Endopod of second pleopod subject to torsion so that ventral groove is not visible in ventral

aspect 4

Endopod of second pleopod not subject to torsion; ventral groove clearly visible in ventral

aspect 5

4. Endopodial armature of second pleopod forming a terminal spiral structure (Figures 24D,E).

A. montanus Mackin and Hubricht

Endopodial armature of second pleopod consisting of two large, heavily sclerotized structures

showing only mild torsion (Figures 51E,F) A. nodulus, new species

5. Lateral process not developed, but mesial process large and bifid, and caudal process wide

and dentate (Figures 23D,E) A. dentadactylus Mackin and Hubricht

Lateral process well developed, caudal process either absent or broadly rounded 6

6. Uropoda about half length of telson (never more than 0.7 telson length); endopodial armature

consisting of a rounded mesial process (not dentate), and a nonsclerotized rounded lateral

process (Figures 12C,D, 15) A. brevicauda Forbes

(for separation of the two subspecies, see Table 3.)

Uropoda subequal in length to telson; endopodial armature not as described for

A. brevicauda 7

7. Mesial process dentate, lateral process sclerotized and pointed, caudal process not developed

(Figures 49D,E, 50) A. scrupulosus, new species

Mesial process not dentate, lateral process rounded, caudal process developed and broadly

rounded with a few rugosities (Figures 25D,E) A. kenki Bowman

8. Mesial process absent 9

Mesial process present 11

9. Caudal process absent (Figures 46D,E, 48) A. laticaudatus, new species

Caudal process present 10

10. Caudal process often with acutely pointed apex; cannula short and wide (Figures 16c,

17D,E, 20) A. intermedius Forbes

Caudal process usually broadly rounded; cannula long and narrow (Figures 5D,E, 10).

A. communis Say

11. Cannula relatively long and narrow 12

Cannula relatively short and wide 13

12. Caudal process usually with an acute apex (Figures 29D,E, 32, 33D,E, 36); first pleopod

subequal in length to second A. racouitxai, new species

(for separation of the two subspecies, see Table 4.)

Caudal process rounded (Figures 21D,E) ; first pleopod distinctly shorter than second.

A. attenuatus Richardson

13. Mesial process usually short and wide, and cannula very wide with a recurved outer lip

(Figures 44C,D, 45) A. obtusus, new species

Mesial process usually long and not very wide, and cannula of moderate width (Figures

37D,E, 41) A. forbesi, new species

(further differences between these two species are given in Table 5.)
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Asellus communis Say

FIGURES 1-6, 8-10

Asellus communis Say, 1818, pp. 427-428.

Not Asellus militaris Hay, 1878, p. 90.

Not Asellus communis Say.—Racovitza, 1920, pp. 79-95, figs.

52-73.

Asellus communis was the first species of North American Asellus to be described. The description was extremely brief and no details were given of the male

sexual pleopods; furthermore, no drawings were included. In view of the inadequacy of the original description, it is uncertain if any of the several subsequent redescriptions, none of which referred to original

type material, in fact applied to A. communis (cf.

Smith, 1874; Richardson, 1905; Racovitza, 1920; Van

Name, 1936).

The description by Racovitza (1920) is of some

importance since it was original in the sense that it

was not based on previous descriptions and was very

detailed. It also provided an extensive bibliography

up to 1920 for the species. The description, however,

was based on two male specimens and one ovigerous

female sent to Racovitza by the United States National Museum from a collection made by W. P. Hay

from the edge of the Potomac River in Virginia, a

locality some 125 miles from the region where A.

communis had apparently been collected by Say for

the original description. The decision to regard these

specimens as conspecific with A. communis appears

to have been quite arbitrary on the part of Racovitza;

indeed it seems that Racovitza did not even sight

Say's description, as indicated by his remarks (p. 79)

under the heading "Type de l'espece."

Unfortunately, no specimens identified by Say

appear now to exist. Say did not mention in the

original description that types had been set aside, but

there is a brief note following a comment on the habitat of the species (p. 427, "Cabinet of the Academy"),

from which we may reasonably conclude that identified

material had been placed in the collections of the

Academy of Natural Sciences of Philadelphia. None of

this material can now be found, according to information received from Mr. C. W. Hart, Jr., the Academy of Natural Sciences of Philadelphia (personal

communication, January 1966), who made a search

on my behalf.

In the absence of material named by Say, it is therefore impossible to determine with absolute certainty

the identity of A. communis or its conspecificity or

otherwise with the species described by Racovitza.

Despite this uncertainty, however, it is clear that the

name A. communis has been the most frequently used

of all specific names when referring to epigean freshwater isopods in North America. Van Name (1936,

p. 456), for example, states that it is "by far the

most abundant and widely distributed isopod in the

eastern half of the United States, also in southern

Canada."

In order to provide a solution to the identity of A.

communis, and as rather precise details were given by

Say of the area from which we may conclude he obtained his specimens, the decision was taken to create

a neotype. This decision, it is felt, is in accord with

the provisions of Article 75, Neotypes, of the International Code of Zoological Nomenclature Adopted

by the XV International Congress of Zoology (1961)

in that the neotype is designated in connection with revisory work and is essential for the identification of

one of a number of closely similar species. Confirmation has been received from four colleagues who work

on or are interested in the taxonomy of North American Asellus species that this procedure is not one

they object to (Drs. E. L. Bousfield, T. E. Bowman,

R. Prins, and H. R. Steeves III).

With reference to the distribution of A. communis, Say noted (p. 427) that it inhabits "small

streams of fresh water, under stones," and (pp. 427-

428) is "a very common species in our fresh water,

particularly in rivulets under stones. It is frequently

introduced with the Schuylkill water into Philadelphia." Bearing this information in mind, a collection

was made at Valley Forge, about 20 miles northwest

of Philadelphia, on 14 April 1967 from Valley Forge

Creek, a small, moderately fast-flowing, stony-bottomed tributary of the Schuylkill River. This locality

is proposed as the restricted type locality. Of the three

male specimens collected, the largest was selected and

designated the neotype.

Comparison of Racovitza's (1920) description with

the description given herein of the neotype of A. communis indicates that two species are involved, that is

the species described by Racovitza is different from

A. communis. The material from which Racovitza

received three specimens in 1920 and upon which

specimens he based his description is fortunately still

in existence and has been used as the type collection
NUMBER 49

for a new species A. racovitzai (see under this

species).

Asellus militaris was described by Hay in 1878. In

a later publication, however, he noted (1882, p. 241)

that the species should be synonymized with A. communis. Probable syntype material of A. militaris still

exists and this, on examination, proved to be conspecific with A. intermedius (see discussion under

this species).

TYPE MATERIAL.—Neotype: adult o*, catalog number 7300, labeled "Asellus communis Say Neotype

(o*)-" Topotypes: two adults o* cf, catalog number

7301, labeled "Asellus communis Say topotypes (2 cf)."

All specimens in the collection of the Academy of

Natural Sciences of Philadelphia and in jar labeled

"Asellus communis Say neotype and topotypic material

collected from Valley Forge Creek, near Philadelphia,

Pa., 14 April 1967 by W. D. Williams."

DESCRIPTION OF NEOTYPE.—Body: Length, 11.0

mm; maximum width, 4.0 mm. Color of live specimens

mottled pale and dark brown. Surface smooth.

Head (Figure 1A) : About twice as wide as long.

Front margin distinctly concave. Eyes moderately large

and quite distinct. Lateral margins of head with numerous simple spines of various lengths.

Thoracic terga: Roughly rectangular, posterior ones

slightly larger than anterior ones, all with short to

long spines on lateral and posterior margins. Second

to seventh terga with anterior angles forming small

lobes increasing in size posteriorly. First tergum (Figure

1B) without such lobes but coxa of first peraeopod

prominent.

First antenna (Figure lc): Flagellum 16-merous

and tip not quite reaching to distal end of last segment

of peduncle of second antenna; penultimate 3 segments bearing aesthetascs. Flagellum and peduncle

subequal in length. All segments of peduncle more or

less subequal in length. First peduncle segment about

twice as long as wide; second and third segments respectively 3 and 4 times as long as wide.

Second antenna (Figure ID) : Length (6.0 mm)

just over half (0.55) that of body. Flagellum 53-

merous and about twice length of peduncle. First, second, and third segments of peduncle stout, each with

several strong simple spines, and about as wide as

long; fourth segment as long as first three combined,

3 times as long as wide; fifth segment about 1.5 times

length of fourth, about 6 times as long as wide.

Lips: Upper lip (Figure 1E) subquadrate with dense

fringe of fine setae distally. Lower lip (Figure IF)

bilobed, each lobe more or less triangular and fringed

with long fine setae distally and marginally.

Mandibles: Each with a large, well-developed 3-

segmented palp, the last 2 segments of which form a

weak claw with its inner margins bearing many spines

each with a fine setose 'comb' distally. Left mandible

(Figure 2A) with 4-toothed incisor process and lacinia;

spine row beneath lacinia of 15 unilaterally plumose

spines. Right mandible of neotype missing, but that of a

topotype (Figure 2B) with a 4-toothed incisor and a

spine row beneath incisor of 16 finely pectinate to

unilaterally plumose spines.

First maxilla (Figures 2c, D) : Inner plate with 5

large plumose spines terminally and numerous fine,

small, simple spines laterally. Outer plate with 11 variously dentate stout spines on distal margin, one long,

fine, plumose spine near lateral distal angle, some small

spines on outer proximal margin, and a fringe of fine

setae on proximal part of inner margin.

Second maxilla (Figure 2E) : Outer plate of 2 subequal laminae; outer lamina with about 22 long to

short, pectinate or dentate spines on distal margin;

inner lamina with 15 such spines on distal margin.

Inner plate bearing a number of simple, plumose or

pectinate spines on distal edge and with a medial dorsal

row of about 36 long, simple spines.

Maxilliped (Figure 2F) : Palp large with many

slender spines on inner margins of segments and a few

strong spines on outer margins. Masticatory lobe with

several simple or plumose spines distally and 5

coupling hooks medially. Epipodite subquadrate, outer

basal angle almost a right angle.

First peraeopod (Figures 3A, B) : Relatively short

and stout, subchelate. Dactylus as long as palm of

propodus, with numerous teethlike spines on inner

margin and ending in a distinct claw. Propodus almost

as long as wide, subquadrate; palm with a single large

triangular projection as tall as width of opposing part

of dactylus and situated near midpoint, a smaller projection between larger projection and point of attachment of dactylus, 2 very strong teethlike spines proximally, and a submarginal row of spines on inner and

outer surfaces. Carpus small, as long as wide, triangular. Merus larger than carpus, slightly wider than long,

subtriangular. Ischium about twice as long as merus,

length about 1.5 times width. Basis subrectangular,
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 1.—Asellus communis, neotype: A, head; B, first tergum; c, first antenna; D, second

antenna; E, upper lip; F, lower lip.
NUMBER 49

FIGURE 2.—Asellus communis, A, C-F, ncotype; B, male topotype: A, left mandible; B, right

mandible; c, first maxilla; D, distal margin of outer plate of first maxilla; E, second maxilla

(dorsal surface); F, maxilliped.
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 3.—Asellus communis, neotype: A, dactylus and palm of first peraeopod; B, first peraeopod; c, second peraeopod; D, third peraeopod; E, fourth paraeopod.
NUMBER 49

about 1.5 times as long as ischium, and twice as long as

wide.

Second peraeopod (Figure 3c) : Longer than but not

as robust as first peraeopod; not subchelate. Dactylus

about half as long as propodus with 5 teethlike spines

on inner margin and a similar terminal spine. Propodus

about 4 times as long as wide, and bearing distally a

sclerotized triangular process. Carpus trapezoidal, twice

as long as greatest width. Merus subtriangular, almost

as long as wide, with some very long and strong spines

at anterodistal angle. Ischium subrectangular, twice as

long as merus and two-thirds as wide as long. Basis

subrectangular, 1.5 times as long as ischium, about

twice as long as wide.

Third peraeopod (Figure 3D) : Similar to second

peraeopod.

Fourth peraeopod (Figure 3E) : Slightly shorter than

second or third peraeopod. Dactylus half as long as

propodus and with 4 teethlike spines on inner margin.

Propodus 3 times as long as wide, notched at point onethird of length from distal end on inner margin with

several long spines proximal to notch and a single triangular projection on distal margin. Carpus bent in

long axis and forming with dactylus and propodus an

almost subchelate structure. Otherwise rather similar

to second peraeopod.

Fifth peraeopod (Figure 4A) : Longer than fourth

peraeopod. Dactylus about two-fifths as long as propodus and with 4 teethlike spines on inner margin.

Propodus about 5 times as long as wide; anterior margin not notched but with several long spines; distal

margin with triangular projection and anterodistal

angle with a strong spine. Carpus more or less straight

along long axis, about twice as long as wide, and threequarters length of propodus. Merus slightly longer than

wide, with a few robust spines at posterodistal angle.

Ischium three-fourths as wide as long, and as long as

carpus; posterior margin with several long spines.

Otherwise rather similar to second peraeopod.

Sixth peraeopod (Figure 4B) : Slightly longer than

fifth peraeopod. Propodus about 4 times as long as

wide. Carpus 2.5 times as long as greatest width.

Otherwise similar to fifth peraeopod.

Seventh peraeopod (Figure 4c): Slightly longer

than sixth peraeopod. Carpus about twice as long as

wide. Otherwise rather similar to sixth peraeopod.

First pleopod (Figure 5A) : Total length of appendage 1.26 times as long as second pleopod. Sympod

subrectangular, about three-fourths as wide as long,

inner margin with 5 hooklike protuberances for coupling. Distal segment also subrectangular, but outer

margin very slightly concave; twice as long as wide, and

about 1.33 as long as sympod; distal margin and distal

half of outer margin bearing numerous short and

simple spines; inner proximal angle with single spine.

Second pleopod (Figures 5B-E) : Sympod subsquare

with single spine near inner distal angle. Proximal segment of exopod with 3 setose and 1 simple spine on

outer margin. Distal segment of exopod ovate with 23

long setose spines marginally and also many very fine

setae arranged in groups of about 3 to 5 on surface

of segment near inner margin. Endopod narrow,

slightly curved medially, about as long as both segments of exopod, two-thirds length of sympod, and

about 3 times as long as greatest width; prominent

inner and outer apophyses occur basally. Cannula of

endopod long and simple, extending beyond caudal

process. Caudal process prominent, rounded, sclerotized, without associated hooks. Mesial process not

evident.

Third pleopod (Figure 6A) : Sympod small. Exopod

forming large operculum for remaining pleopods,

ovate; suture between proximal and distal segments

running obliquely and proximally; outer and distal

margins of distal segment with many relatively long

plumose spines, inner submargin with several short

simple spines; outer margin of proximal segment with

many simple spines, and short simple spines also present along suture with distal segment. Endopod small

and ovate.

Fourth pleopod (Figure 6B) : Sympod small. Exopod

ovate and with a row of relatively long simple spines

and very short fine setae along outer proximal margin.

Endopod ovate, smaller than exopod.

Fifth pleopod (Figure 6c) : Exopod subrectangular, about 1.5 times as long as wide, and with several

long simple spines (but no fine setae) along outer

proximal margin.

Uropod (Figures 4D, 6D) : Slightly shorter (0.89)

than telson. Peduncle about twice as long as greatest

width, with many marginal spines. Exopod two-thirds

(0.69) length of peduncle; endopod about as long as

(0.92) peduncle and 3 times as long as greatest width.

Telson (Figure 6D) :Subcircular, as long as wide;

apex obtusely pointed, and lateral and posterior margin with numerous simple and relatively short spines.

MATERIAL EXAMINED.—Apart from the neotype and

the two topotypes (in part), the following material
10

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 4.—Asellus communis, neotype: A, fifth peraeopod; B, sixth peraeopod; c, seventh peraeopod; D, uropod.
NUMBER 49 11

FIGURE 5.—AseUus communis, neotype: A, first pleopod; B, second pleopod; c, dorsal surface of

endopodite of second pleopod; D, E, respectively dorsal and ventral surfaces of tip of endopodite

of second pleopod.
12

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 6.—Asellus communis, neotype: A, third pleopod; B, fourth pleopod; c, fifth pleopod;

D, uropod and telson.
NUMBER 49 13

was examined and considered to be A. communis;

such differences as occurred from the neotype were

considered to be insignificant at the species level.

NOVA SCOTIA: Argyle stream, Yarmouth

County, 3c?cf, coll. E. L. Bousfield, 28.vi.1958

(NMC) ; stream near Doctor's Cove, Shelbourne

County, 1 <?, coll. E. L. Bousfield, 28.vi. 1950 (NMC);

Pubnico Lake, Yarmouth County, 5cf cf, coll. E. L.

Bousfield, 21.vi.1956 (NMC).

ONTARIO: Lynn River, lcf, coll. Ontario Dept.

P. & D., 10.vi.1955 (NMC); Chaffey's Locks, Leeds

County, Id1, coll. I. M. Smith, 4.ix.l965 (ROM).

COLORADO: Independent Reservoir, Boulder

County, 4cfcfj coll. S. J. Herrmann, 18.iv.1967;

Longmount Power Station Lake, Boulder County,

7 cf cf, coll. S. J. Herrmann, 18.iv.1967; Mirror Lake,

Larimore County, oo cf cf, coll. S. J. Herrmann, 26.iv.

1967; Kid's Lake, Larimore County, 30 cf cf, coll. S. J.

Herrmann, 26.iv.1967; Meadow Lake, Larimore

County, oo cf cf, coll. S. J. Herrmann, 26.iv. 1967; Rainbow Lake, Larimore County, oo cf cf, coll. S. J. Herrmann, 26.iv.1967; Sunset Lake, Boulder County,

oo cf cf, coll. S. J. Herrmann, 26.iv.1967; Willow Lake,

Larimore, oo cf cf, coll. S. J. Herrmann, 26.iv.1967.

MAINE: Bangor, 2cf cf, coll. J. Brower, 21.iv.1962.

MARYLAND: Hall's Creek, Dunkirk, Calvert

County, 2 cf cf, coll. R. H. Greenfield and W. H. Ball,

25.vi.1934 (USNM).

MASSACHUSETTS: Cambridge, 1 cf, coll. Wheatland, April 1860 (MCZ); Cambridge, 8cfcf, coll.

Wheatland, 21.iv.1860 (MCZ); (?) Cambridge,

2 cf cf, collector and date not marked (MCZ); Salem,

11 cf cf, coll. Boston Society of Natural History, date

not marked (MCZ); Beaver Brook, Danvers, oo cf cf,

coll. H. W. Winkley, date not marked (USNM); Red

Brook Pond, 3cf cf, coll. E. L. Bousfield, ll.ix.1963

(NMC); Witch Brook and Crocker Pond, 8cf cf, coll.

E. L. Bousfield, 24.ix.1965 (NMC).

NEW JERSEY: Swamp back of Orange Mountains, oocfcf, coll. E. G. Mitchell, 1906 (USNM);

Lakehurst, 1 cf, coll. D. Barr, 16.V.1962 (ROM); New

Lisbon, 3cf cf, coll. D. Barr, 16.V.1962 (ROM); Lakehurst, 2cf cf, coll. D. Barr, 17.V.1962 (ROM).

PENNSYLVANIA: Conestoga River Lancaster

County, 6cf cf, coll. H. W. Levi, June 1948 (MCZ).

VERMONT: Lake Champlain,* 2cf cf, coll. E. L.

Bousfield, 19.vi.1956 (NMC).

WASHINGTON: Echo Lake,* King County,

2cf cf, coll. E. L. Bousfield, 20.vii.1955 (NMC).

WEST VIRGINIA: Halltown, 6cfcf, coll. B.

Bryan, date not marked (USNM).

Collections marked by an asterisk contained more

than one species. Many of the collections in addition

to males included juveniles and nonovigerous and

ovigerous females, but since it is at present not possible

to identify such material, no note of their occurrence

is made. These two comments apply generally to all

collections referred to in subsequent pages of this

paper.

GEOGRAPHICAL DISTRIBUTION.—Figure 7 shows the

geographical distribution of all localities detailed

above (except those of uncertain position) as well

as the position of the restricted type locality. It indicates that the species mainly occurs in the northeastern part of the United States and the southeastern

part of Canada. There are two disjunct regions, however, where the species has also been recorded: Colorado, where it was recorded from eight different

localities in the Denver area; and the State of Washington, where the species was recorded together with

A. racovitzai in Echo Lake, King County. Material

from both regions was examined with particular care,

but as far as the present author could discern all specimens appeared clearly to be conspecific with material

of A. communis from the eastern part of North

America.

The material from Echo Lake was collected by Dr.

E. L. Bousfield, and his notes upon the locality are

of considerable interest; he wrote (personal communication, 1 September 1967):

Echo Lake is the type locality of Crangonyx richmondensis

occidentals H. & H., one of a species complex that is usually

found together with A. communis in the east. . . . Crangonyx

pseudogracilis Bousf., formerly thought to be endemic to

eastern North America, has also turned up in material from

Oregon and Washington [cf. Bousfield, 1961], and indicates

that fresh-water peracaridans may have much wider distributions than formerly believed.

In this connection, the records of "A. communis" by

Hatch (1947) are also of some interest; while no

certainty can be attached to his specific determinations, the mention of material from the Lake Washington drainage basin (p. 171) with a single prominent

tooth on the inner margin of the posterior surface of

the propodus of the male first peraeopod suggests that

he too might have been dealing with a "typically"

eastern species, for males of A. occidentalis, the only

widespread western species known, lack such a tooth.
14

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

• A. communis

A A. montanus

A A. dentadactylus

FIGURE 7.—Geographical distribution.

One cannot rule out in the case of the Washington

material missorting of labels (the material was not

sorted by Bousfield personally); but this eventuality

could hardly have occurred in the case of the material

from Colorado, which was collected only a short time

before my receipt of it. Artificial transference from the

eastern States cannot perhaps be ruled out for the

Colorado localities, since all are situated in a region

with extensive numbers of artificial water bodies and

reservoirs, and such waters are frequently recipients of

food stocking (invertebrates) on the part of angling

associations. Asellus is well known to be a nutritive fish

food, but appears naturally to be rare or absent in

most of the region to the north of Colorado. Thus, Dr.

W. N. Rosine of Augustana College, South Dakota,

wrote (personal communication, 11 May 1967):

I have collected amphipods rather extensively in South Dakota, Nebraska and Minnesota and have come across isopods

only once. .. . I must say that over the years I have been

rather surprised by the lack of isopods in this part of the

county. .. . it seems to me that if they were even occasionally present around here then I would have found them

at some time or another. Collecting in Colorado produced

the same experience. Visits in that State to literally hundreds

of lakes, springs and streams yielded only two collections in

the early 1950s.

ECOLOGY.—From the limited locality data upon

labels in the collections of material examined, it seems

that A. communis may occur in a wide variety of inland waters: from creeks, rivers, ponds, lakes, reservoirs, and, in one instance, from a swamp. At least

with regard to choice of macrohabitat the species

appears to be wide ranging. It does not, however, seem

to be present in any of the Great Lakes, as it was never

recorded in any of the numerous collections that I

have examined from these waters. Hatchett (1947)

commented upon the ecology of "A. communis" in

Michigan at length, but as the characters he used to

identify Michigan species of Asellus (number of segments in flagellum of first antenna, head shape) are

variable and show no well-defined specific differences,

the identity of his species remains uncertain. For the

same basic reason, several other reports containing ecological data on "A. communis" must also be ignored.

FURTHER DESCRIPTION ( 6* ).—This account, unless

specifically noted otherwise, is based only upon mate-
NUMBER 49 15

10

^ 30 5 0 100 150

Length of body (mm.)

190

FIGURE 8.—Asellus communis. Relationship between length

of second antenna and length of body: (•) eastern specimens;

(x) Colorado specimens; (o) specimens from Washington

State.

rial from the eastern part of North America, but

the variation recorded is nevertheless inclusive for

western material.

Body: The smallest male with well-developed secondary sexual characters was 4.0 mm long; the largest

male examined was 18.0 mm.

First antenna: Flagellum 6- to 17-merous, the number of articles depending to some extent upon the size

of the specimen; flagellum tip reaching to midpoint of

last peduncle segment of second antenna or almost to

distal end of this segment.

Second antenna: Length from just over half to

same length as body, the fraction showing a rough

inverse correlation with absolute body size. This relation is indicated in Figure 8 in which are plotted the

appropriate values for the largest male in each of 27

collections, including those from Colorado and

Washington (indicated differently). Flagellum 36- to

82-merous, the number of segments generally increasing with the length of the specimen.

Mouthparts: See Table 1.

First peraeopod: 2 to 4 (usually 3) very strong teethlike spines at proximal end of palm. Some variation

occurs in the shape of the palm and its triangular

process (cf. Figure 9).

First pleopod: Total length of appendage 1.0 to

1.47 (usually 1.1) times as long as second pleopod.

FIGURE 9.—Asellus communis, extent of variation in palm

shape of male first peraeopod: A, Leeds County, Ontario;

B, Lake Champlain, Vermont; c, Witch Brook and Crocker

Pond; D, Echo Lake, Washington; E, Yarmouth County, Nova

Scotia; F, Bangor, Maine; G, Meadow Lake, Larimore County,

Colorado; H, Kid's Lake, Larimore County, Colorado; i,

Salem, Massachusetts.

Inner margin of sympod with 3 to 6 coupling hooks.

Outer margin of distal segment straight to slightly

concave.

Second pleopod: One to a few simple spines near

inner distal angle of sympod. Proximal segment of exopod with 2 to 4 spines on outer margin, and distal

segment with 19 to 24 marginal spines. Although no

gross variations in the morphology of the tip of the

endopodite occur, there are nevertheless minor morphological variations occurring between specimens

from the same locality and also from different

localities; Figure 10 illustrates the range of such

variation. As indicated, the cannula may vary in length

and may not extend beyond the caudal process or may

distinctly do so. The caudal process itself may be no

more than a slightly rounded distal protuberance, or

may be quite prominent and even in some cases obtusely pointed. The typical morphology is as illustrated

in Figures 5D,E for the neotype. For purposes of comparison, Figure 10 also indicates the structure of the

endopoite tip of a specimen from Echo Lake, Washington, and Independent Reservoir, Colorado.

Uropod: See Table 2.

3T8-61S O - 70 - 2
16 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

-

S

.8

i

l

11

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I -3

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if

i

-y

tnptpou -y

stuojrufnjx ~

snsniqo -y

tstqjof-y

sipijsno

wijtaowi -y

-y

m

y

smpnujupti -y

vpnonanq -y

vpnvnaaq

V

swnunuos -y

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10

 2 5 1 4.

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CM —

CM —« 16-26 10-19 15-18 12-14 18-28 15-18

eo m

3-8 4-5 6-8

$?JJ *

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ill
NUMBER 49 17

FIGURE 10.—Asellus communis, extent of variation in morphology of endopodite tip of male

second pleopod: A, Lynn River, Ontario; B, Orange Mountains, New Jersey; c, Toronto, Ontario;

D, New Lisbon, New Jersey; E, F, Lakehurst, New Jersey; o, Hall's Creek, Maryland; H, Bangor,

Maine; i, K, Cambridge, Massachusetts; j , Pubnico Lake, Nova Scotia; L, Echo Lake, Washington; M, Independent Reservoir, Colorado.

TABLE 2.—Variation in certain features of uropod of North American epigean Asellus species

[Except where indicated, males only, and data from examination of all available material]

uropod length

telson length

Range

0. 86-1. 20

0.48-0.68

0. 36-0.44

0. 6 -1. 1

1.0

0. 95-1. 3

1.0 -1.5

1.1 -1.2

0. 70-1. 00

0. 80-1. 50

0. 67-1. 5

1.0 -2. 0

1.0 -1.2

0. 95-1. 28

0. 88-1. 21

0. 67-1. 25

M

1.01

0.52

0.41

0.87

_

_

_

_

0.90

1.12

1.16

1.48

1.08

1.04

1.03

0.88

±S.D.

0.08

0.07

0.03

0.14

_

_

_

_

0.11

0.19

0.20

0.32

0.06

0.12

0.12

0. 16

exopod length

peduncle length

Range

0. 55-1. 20

0. 68-1. 07

0. 64-0. 91

0. 62-1. 23

1.2

0. 63-0. 75

0. 39-0. 65

0. 54-1. 1

0. 58-1. 22

0. 57-1. 16

0.45-0. 95

0. 71-1. 31

0. 62-0. 68

0. 64-0. 85

0. 67-1. 07

1.00-1.50

M

0.75

0.86

0.76

0.84

_

_

-

-

0.84

0.73

0.69

0.91

0.66

0.75

0.90

1.27

±S.D.

0.18

0.13

0.09

0.16

-

_

-

-

0.17

0.15

0.10

0.15

0.02

0.04

0. 15

0.19

endopod length

peduncle length

Range

0.82-1.60

0. 90-1.21

0. 85-1.00 <

1.0 -1.6

1.3

0. 91-1.0

0.80-0.86

1.0-1.26

0.90-1.58

0. 89-1. 32

0. 72-1. 23

0.91-1. 52

0.95-1. 06

0.85-1. 03 (

1. 35-1. 87

1. 21-2. 00

M

1.08

1.05

X92

1.20

1.15

1.03

1.01

1.13

LOO

).96

1.52

.52

±S.D.

0.19

0.14

0.07

0.15

-

-

-

-

0.16

0.10

0.13

0.15

0.04

0. 11

0.23

0.25

A. communis

A. brevicauda brevicauda

A. brevicauda bivittatus

A. intermelius

A. attenuatus «

A. dentadac'ylus *>....

A. montanus b

A. kenki '

A. racovitzai racovitzai.

A. racovitzai australis..

A.forbesi

A. obtusus

A. laticaudatus

A. scrupulosus

A. nodulus

A. occidentals

• From paralectotype (cf).

» From text and drawing of Mackin and Hubricht (1938)

and lectotype (apparently applies to both sexes).

0

 From text and drawings of Bowman (1967) and original

(applies to both sexes).
18

Asellus brevicauda Forbes

Asellus brevicauda Forbes, 1876, pp. 8-10.—Richardson,

1905, pp. 423-425, figs. 477-479.—Van Name, 1936, pp.

462-463, fig. 290.

Asellus brevicaudus Mackin and Hubricht, 1938, pp. 631-

632.

Asellus bivittatus Walker, 1961, pp. 385-390, figs. 1-5.

Asellus brevicauda was described by Forbes in 1876,

but the description though rather lengthy did not include details of those parts of the body of most taxonomic significance; it did not, moreover, include drawings despite Richardson's indication (1905, fig. 477)

that it did, and it was obviously a composite description based on several specimens. A later description by

Richardson (1905) seems to be original in that it was

not based entirely on Forbes' description and contained additional (but relatively unimportant) descriptive material. It was based upon a single specimen, but Richardson made no comment as to where

this came from, and neither her description nor the

original one of Forbes' mentions deposition of type

material. In Richardson's redescription of A. intermedius in the same paper (pp. 422-423), however, she

mentions that she had been sent "types" [sic] of A.

intermedius from the Museum of Comparative Zoology

of Harvard University, and since this species was described by Forbes at the same time he described A.

brevicauda, it seems possible that Richardson was sent

similar material for A. brevicauda, although she does

not say so. At all events, inquiries to the curator at the

Museum of Comparative Zoology, Dr. H. W. Levi, revealed the presence in the collections of that institution

of a single male specimen of Asellus in a tube with the

label: "MCZ Illinois; Union Co., July 30, 1876; S. A.

Forbes coll. Asellus brevicauda Forbes." Bearing in

mind Forbes' only statement (1876, p. 10) about the

distribution of the species, namely that it is found in

Jackson and Union counties in southern Illinois, and

the fact that other crustaceans collected on 30 July

(Gammarus fasciatus Say, p. 6) and in 1876 (Eubranchipus serratus Forbes, pp. 13-14) were referred to in

the same paper, the circumstantial evidence is very

strong that this specimen is a syntype.

According to Dr. H. W. Levi (personal communication, 13 September 1967), the specimen was originally deposited in the^ Peabody Academy of Science

and later transferred. It could have been so deposited

by Forbes as a result of his contact with S. I. Smith

of Yale College (cf. Forbes, 1876, p. 3), although in

view of Forbes' position as curator of the Illinois

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Museum of Natural History deposition in his own institution would have been normal. The Illinois Natural

History Survey, although possessing syntype material

of A. intermedius, did not possess syntype material for

A. brevicauda (Dr. J. D. Unzicker, personal communication, 5 June 1967). The specimen from the Museum

of Comparative Zoology is accordingly now designated

as the lectotype of A. brevicauda. It is not certain that

this is the actual specimen examined in 1905 by

Richardson, but because its dimensions correspond to

those given by Richardson this seems likely.

Apparently under the impression that the specific

name brevicauda was adjectival, Mackin and

Hubricht (1938) altered it to brevicaudus to seem to

agree in gender with the genus name. It is, however,

a noun, and the original spelling is correct.

Asellus bivittatus was described by Walker (1961)

from a stream, Doe Run, in Meade County, Kentucky.

Unfortunately, although her description was very detailed in most respects, she omitted critical details concerning the morphology of the tip of the endopodite

of the male second pleopod, stating only (p. 388),

"pore at distal end giving appearance of bifurcation."

She provided a figure of the second pleopod of the

male, but it was at too small a scale to provide clarification. Her type material is deposited in the United

States National Museum, and reexamination of the

sexual pleopods of the holotype as well as male topotypic material kindly given me by Prof. H. B. N.

Hynes and Dr. L. A. Krumholz revealed that the morphology of the tip of the endopodite of the second

pleopod was almost identical with that of the lectotype

of A. brevicauda. Her taxon is therefore regarded as

conspecific with A. brevicauda. There seem to be,

nevertheless, differences between other parts of the

morphology of her taxon and the lectotype of A. brevicauda, and these are such that it is appropriate at

present to accord her taxon subspecific status.

It should be noted that both Walker's taxon and

what she regarded as "somewhat differentiated" A.

brevicauda occur in the same stream, although spatially

separated (see also Minckley, 1963, who regarded

such material as aberrant A. bivittatus). It is perhaps

possible that the differences displayed by her taxon are

no more than phenotypic variations of typical A.

brevicauda brought about by the physical nature of

the environment (upper reaches of Doe Run, associated

with the moss Fissidens). Some of the significant distinguishing criteria of Walker's taxon, according to
NUMBER 49 19

Walker, are small size and body color pattern. The

present author has been unable to examine a collection

of small males of A. brevicauda brevicada and unable

to compare the color patterns of live specimens from

the upper reaches of Doe Run and A. brevicauda brevicauda. Until such examination and comparison have

been made, preferably on material gathered entirely

from Doe Run, subspecific status for Walker's taxon is

appropriate. It may be added that through the courtesy

of Dr. L. A. Krumholz, University of Louisville, an attempt to examine live material from Doe Run was

made, but unfortunately the material did not survive

the postal journey.

Asellus brevicauda brevicauda Forbes

FIGURES 11, 12,14

Asellus brevicauda Forbes, 1876, pp. 8—10.

Asellus brevicaudus Mackin and Hubricht, 1938, pp. 631-632.

TYPE MATERIAL.—Lectotype, adult <S, deposited in

the Museum of Comparative Zoology; the reference

is the specific name (catalog number 6800) : Labels

read: "MCZ Illinois: Union Co., July 30, 1876; S. A.

Forbes coll. Asellus brevicauda Forbes" and

"hololectotype."

DESCRIPTION OF LECTOTYPE.—Body: Length, 13.0

mm.

Head (Figure 1 1A) : Eyes large and distinct; posterolateral lobes large, prominent and rounded, and with

numerous strong spines.

First antenna (Figure 11B): Flagellum 12-merous

and tip reaching to point about two-thirds distally

along last segment of peduncle of second antenna;

penultimate 2 segments bearing aesthetascs. Flagellum

about two-thirds length of peduncle. First segment of

peduncle slightly shorter than second; third segment

about half length of second. First segment of peduncle

about twice as long as wide and bearing distally a

circlet of short strong spines; second and third segments

respectively about 3 and 2.5 times as long as wide.

Second antenna: Length (8.0 mm) about threefifths (0.62) that of body. Flagellum 80-merous. Fourth

and fifth segments of peduncle respectively about 2.5

and 4.5 times as long as wide, but peduncle otherwise

similar to A. communis.

First peraeopod (Figure lie): Dactylus slightly

longer than palm with 8 teethlike spines on inner margin and ending in a long terminal claw. Propodus

about three-fifths (0.61) as wide as long, and subtrapezoidal in shape; palm with a small, low, conical

projection near midpoint, a very large toothlike spine

proximally, and a submarginal row of spines on inner

and outer surfaces.

Second to seventh peraeopoda: Similar in construction to A. communis; most noticeable minor difference

is occurrence of fewer teethlike spines on inner margin of each dactylus.

First pleopod (Figure 12A) : Total length of appendage slightly greater (1.15) than that of second pleopod.

Sympod subrectangular, about three-fifths as wide as

long; inner margin with 7 hooklike protuberances for

coupling. Distal segment also subrectangular, but distinctly curved outward so that the outer lateral margin

is deeply concave and the inner lateral margin is convex; proximal width slightly greater than distal width;

maximum width slightly less (0.47) than half maximum length; distal margin bearing 11 long plumose

spines and 9 shorter simple spines somewhat irregularly arranged; lateral distal angle with a row of short

strong spines arranged regularly; inner proximal angle

with 2 short simple spines.

Second pleopod (Figures 12B-D) : Sympod subrectangular, maximum length over one and a half

(1.65) times maximum width; medial and lateral margins more or less straight, and medial margin bearing

4 simple spines beneath attachment of endopodite.

Proximal segment of exopod with 7 simple spines on

outer margin, inner margin conspicuously sclerotized.

Distal segment of exopod subtriangular with 17 long

plumose spines marginally and conspicuously sclerotized near inner proximal angle. Endopod narrow and

gently curved outward in long axis, total length subequal to that of exopod; a prominent inner basal

apophysis and a less prominent outer basal apophysis

are present. Cannula short and wide and completely

overlapped ventrally by a flattened, expanded, and

rounded lateral process. Ventral groove prominent,

moderately long and wide. Mesial process large,

sclerotized, and expanded so that it wholly occupies

the inner lateral margin of the endopod tip; distally

its outer face is concave. Caudal process not developed,

but dorsal surface of distal tip of endopod with several

minute, short spinules.

Uropod (Figure 1 ID) : About half as long (0.48) as

telson. Peduncle about as wide as long and bearing

distally numerous short to moderately long spines; subtriangular in shape. Exopod as long as peduncle and

about twice as long as greatest width; endopod slightly
20

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 11.—Asellus brevicauda brevicauda, lectotype: A, head; B, first antenna; c, dactylus and

propodus of first peraeopod; D, uropod; E, telson.
NUMBER 49 21

E

F

G

H

FIGURE 12.—Asellus brevicauda brevicauda, A-D, lectotype; E-I, extent of variation in palm shape

of male first peraeopod in nontype material: A, first pleopod; B, second pleopod; c, D, respectively dorsal and ventral surfaces of tip of endopodite of second pleopod; E, Goose Creek,

Jefferson County, Kentucky; F, Harine, Jefferson County, Missouri; o, Boone County, Missouri;

H, near Fountains Gap, Monroe County, Illinois; i, Burkesville, Monroe County, Illinois.
22

longer than peduncle (1.13) and also about twice as

long as greatest width; both exopod and endopod

bear numerous strong and relatively short spines.

Telson (Figure HE ) : Subcircular, as long as wide;

uropodal sinuses prominent.

MATERIAL EXAMINED.—ILLINOIS: Fountain Gap,

Monroe County, oo cf cf, coll. L. Hubricht, 26.V.1937

(USNM); Burkesville, Monroe County, oo cf cf, coll.

L. Hubricht, 6.xi.l937 (USNM); Bluffside, St. Clair

County, cocfcf, coll. L. Hubricht, 16.L1938

(USNM); Burkesville, cocfcf, coll. Burk et al.,

24.i.l947 (INHS); Shawnee National Forest, Union

County, lcf, coll. R. L. Iippson, 7.iv.l967.

KENTUCKY: Goose Creek,* Jefferson County,

lcf, coll. G. A. Cole, 4.V.1955.

MISSOURI: Glencoe Creek, St. Louis County,

ootfcf, coll. L. Hubricht, l.iii.1936 (USNM);

Harine, Jefferson County, oo cf cf, coll. L. Hubricht,

21.V.1936 (USNM); Gray Summit, Franklin County,

oocfcf, coll. L. Hubricht, 29.V.1937 (USNM);

Antonia, Jefferson County; oo cf cf, coll. L. Hubricht,

6.vi.l937 (USNM); St. Louis, oocf cf, coll. L. Hubricht, 25.xi.1937 (USNM); Cave brook, Boone

County, oo cf cf, coll. C. Boll, 6.X.1956 (NMC).

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

localities detailed above, together with the type locality, are plotted in Figure 13. From some of the localities, A. brevicauda has been recorded by Mackin and

• A. brevicauda

o A. brevicauda

A A. laticaudatus

bivittatus

FIGURE 13.—Geographical distribution.

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Hubricht (1938); none of their additional records are

plotted. This procedure gives greater certainty to and

does not detract substantially from the conclusions that

may be drawn from Figure 13, since they recorded

A. brevicauda from only one additional State, Arkansas

(1 locality). From Figure 13 it is clear that A. brevicauda brevicauda occurs in a large but relatively restricted area of east-central United States, south of

Lake Michigan.

According to the data on labels in the collections

examined, A. brevicauda brevicauda is typically a

species associated with springs or spring-fed streams.

It has also been collected on a few occasions, however,

from cave streams, from which macrohabitat A. brevicauda was recorded also by Mackin and Hubricht

(1938).

FURTHER DESCRIPTION (cf).—Body: The largest

male examined was 17.0 mm long, and the smallest

8.5 mm.

First antenna: Flagellum 11- to 17-merous; flagellum tip reaching to midpoint or slightly beyond the

distal margin of the last segment of the peduncle of

the second antenna; penultimate 2 or 3 segments bear

aesthetascs.

Second antenna: Length 0.53 to 0.76 times that of

body. Flagellum 60- to 124-merous.

Mouthparts: See Table 1.

First peraeopod: Nearly always only one thick toothlike spine is present at proximal end of palm, but occasionally a smaller similar spine is also present. The

small, low conical process near the midpoint of the

palm, likewise, is almost invariably present; it was

absent, however, in one male specimen examined.

Dactylus with 8 to 14 teethlike spines on inner margin.

Propodus 0.5 to 0.72 times as wide as long, but about

two-thirds is the usual value. Figures 12E-I illustrate

the range of variation which may occur in the shape

of the palm. The typical shape is as shown by the

lectotype (Figure lie).

First pleopod: Total length of appendage 1.03 to

1.24 times as long as second pleopod. Inner margin of

sympod with 4 to 7 (usually 6 or 7) coupling hooks.

Maximum width of distal segment 0.43 to 0.52 times

maximum length; distal margin bearing 5 to 11 long

setose spines and 6 to 9 shorter simple spines somewhat

irregularly arranged; lateral distal angle with a row

of 7 to 11 short strong spines arranged more or less

regularly.
NUMBER 49 23

FIGURE 14.—Asellus brevicauda brevicauda, extent of variation in shape of sympod, endopod, and exopod of male second

pleopod: A, near Fountains Gap, Monroe County, Illinois;

B, Burkesville, Monroe County, Illinois; c, Goose Creek,

Jefferson County, Kentucky; D, Harine, Jefferson County,

Missouri; E, Franklin County, Missouri; F, Antonia, Jefferson

County, Missouri; o, St. Louis, Missouri.

Second pleopod: Maximum length of sympod from

1.37 to 2.00 times maximum width; medial and lateral

margins of sympod more or less straight to slightly convex. Proximal segment of exopod with 3 to 7 simple

spines on outer margin; distal segment with 12 to 17

long setose spines marginally, and subovate to elongate

triangular in shape. The morphology of the tip of the

endopodite displays very little variation. The greatest

variation that occurs in the second pleopod involves

the length/width ratio of the sympod, the shape of the

distal segment of the exopod, and the relative positions of the distal tips of the exopod and endopod.

Figure 14 illustrates the nature of this variation.

Uropod:SeeTable2.

Asellus brevicauda bivittatus Walker, new combination.

FIGURE 15

Asellus bivittatus Walker, 1961, pp. 385-390, figs. 1-5.

TYPE MATERIAL.—Walker (1961) gives the following information concerning the deposition and collection of the types of her taxon: Holotype: adult cf 4.3

mm in length, USNM 107465. Paratypes: a series of

100 specimens, USNM 107466. Type locality: Doe

Run, Meade County, Kentucky, approximately 3 miles

east and 0.4 miles north of Ekron. The type material

was collected 24 October 1959.

PARTIAL REDESCRIPTION OF HOLOTYPE.—As previously indicated, Walker's description of her taxon is

detailed, the only significant omission being information upon the morphology of the tip of the endopodite

of the male second pleopod (her omission of a description of the mouthparts is not significant). A reexamination of the holotype enables the description now to

be completed.

Second pleopod (Figure 15): Sympod subrectangular, maximum length 1.34 times maximum width.

FIGURE 15.—Asellus brevicauda bivittatus, holotype: dorsal

surface of right second pleopod.
24

Endopod rather wide, about half as wide as long.

Dorsal surface of endopod near distal margin lacking

minute spines, but otherwise morphology of tip of

endopodite closely similar to that of A. brevicauda

brevicauda (see Figures 12c, D) .

MATERIAL EXAMINED.—KENTUCKY: Doe Run,

Meade County, oocfd1, coll. W. L. Minckley,

4.viii.l962; Doe Run, Meade County, 10 cfcf, coll.

L. A. Krumholz, 22.viii.1967.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

only locality from which A. brevicauda bivittatus is

known is the type locality (Figure 13). This lies in the

southern part of the range of the nominate subspecies.

According to Minckley (1961), Doe Run is a large

spring-fed creek with an average flow of 50 cubic feet

per second. Only the upper 3 miles of the creek are

inhabited by A. brevicauda bivittatus. Minckley

(1963) provides a detailed description of the locality.

SEPARATION OF A. brevicauda bivittatus FROM THE

NOMINATE SUBSPECIES (cf o* only).—Comparison of

Walker's description of A. brevicauda bivittatus with

the description of A. brevicauda brevicauda given

in this paper indicates that the principal differences

between the two taxa are that A. brevicauda bivittatus

is shorter in total length, has fewer segments in the

flagella of its first and second antennae and fewer teethlike spines on the dactylus of its gnathopod, lacks a

triangular process near the midpoint on the palm of

the propodus of the gnathopod, has a propodus which

is only half as wide as long, bears fewer spines on the

distal segment of the first pleopod and on the exopod

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

of the second pleopod, and has a slightly shorter

uropod. A consideration of topotypic material of A.

brevicauda bivittatus negates one of these differences

but supports the remainder. The one it negates is that

relating to the width/length ratio of the propodus of

the gnathopod; this ratio in A. brevicauda bivittatus

(0.61 to 0.68) is similar to that displayed by A. brevicauda brevicauda. The principal differences between

the two subspecies, as indicated by the material at my

disposal, are shown in Table 3, which includes a further difference not apparent from the comparison of

Walker's paper, namely that the distal segment of the

first pleopod of A. brevicauda bivittatus is broader

relative to length than it is in the nominate subspecies.

Also the spines on the uropoda of A. brevicauda bivittatus are longer relative to the length of the rami than

they are in A. brevicauda brevicauda.

Asellus intermedius Forbes

FIGURES 16-18, 20

Asellus intermedius Forbes, 1876, pp. 10-11.—Richardson,

1905, pp. 422-423, figs. 474-476.—Van Name, 1936, pp.

456-457, fig. 286.—Ellis, 1961, pp. 80-102, figs. 1-4.

Asellus militaris Hay, 1878, pp. 90-92.—Mackin, 1940, pp.

17_18._Van Name, 1942, p. 317.

Although Forbes' original description in 1876 of A.

intermedius lacked drawings, it did give a rather complete description of the species except for critical details of the morphology of the tip of the endopodite

of the second pleopod; about this Forbes wrote only

TABLE 3.—Principal differences between Asellus brevicauda brevicauda and Asellus brevicauda bivittatus

[Males only]

A. brevicauda brevicauda A. brevicauda bivittatus

Maximum body length (mm)

Number of segments in flagdlum of first antenna

Number of segments in flagellum of second antenna

Number of teethlike spines on dactylus of gnathopod

Triangular process near midpoint of palm of propodus

Number of coupling hooks on sympod of first pleopod

Width/length ratio of distal segment of first pleopod

Number of setose spines on distal segment of first pleopod

Length/width ratio of sympod of second pleopod

Number of setose spines on distal segment of exopod of second pleopod

Uropod length/telson length ratio

17.0

11-17

60-124

6-14

presentb

4-7

0. 40-0. 50

5-11

1. 37-2. 00

12-17

0. 48-0. 68

5.5"

8-9

31-44

5-6

absent

3-4

0. 50-0. 62

4-6

1.25-1.60

5-10

0. 36-0.44

• Dr. L. A. Krumholz (personal communication, 23 August

1967) reports a maximum length of 7-8 mm.

» Rarely absent (one specimen noted).
NUMBER 49 25

(p. 11), "the outer terminal angle is prolonged into

an incurved process, the inner provided with a movable (?) excurved claw." Forbes did not mention

deposition of types, but in the redescription by Richardson (1905), which included drawings of the first and

second pleopoda, Richardson mentioned she had been

sent "types" [sic] from the Museum of Comparative

Zoology of Harvard University. Her redescription was

based on this material, but unfortunately, like Forbes,

she omitted details of the endopodite tip of the second

pleopod. Inquiries directed to Dr. H. W. Levi of the

Museum of Comparative Zoology revealed that this

institution possessed no collection clearly labeled as

the type of A. intermedius, but it did possess a collection consisting of three male specimens and one

female specimen of Asellus labeled "Asellus intermedius

Forbes S.A. Forbes Union Co. 111."

As the United States National Museum, with which

institution Richardson was associated, also does not

possess material labeled as the type of A. intermedius

(T. E. Bowman, personal communication, 9 March

1967), we may reasonably assume that the collection

examined by Richardson and referred to as type material was returned to the Museum of Comparative

Zoology and is the same collection as that referred to

above. Although no date of collection is given, the

indication that the material had been collected by

Forbes himself, and from an area within which he

had collected specimens for the original description

("hill country of southern Illinois"), provides strong

circumstantial evidence that the material is syntypic.

This material, however, if it is syntypic, is not the only

such material in existence. Inquiries to the Illinois

Natural History Survey revealed the presence of two

collections of Asellus, each one labeled "cotypes." One

was labeled, "Cotypes Asellus intermedius Forbes" and

"Callahan Cr. Cobden. 111. May 30,1876 S. A. Forbes"

and contained five males and six females. The other

was labeled, "cotypes Asellus intermedius Forbes" and

"Stoneft. Cr. Makanda 111. Jy 30, 1876. S. A. Forbes,"

and contained 13 males and 38 females; 2 of these

males belonged to the taxon A. brevicauda brevicauda,

whereas the other males belonged to a different taxon.

The first of the two collections contained males belonging to a single species only, and since it predates

the second collection, it is here regarded as consisting

of syntype material and from it a lectotype and paralectotypes have been designated.

Asellus militaris was described without drawings by

Hay in 1878. Shortly afterward (1882, p. 241) he

commented that his taxon was the same as A. communis and this synonymy was accepted by Richardson

(1905) and Van Name (1936). It was not accepted,

however, by Mackin (1940) who regarded A. militaris

as a valid species. Irrespective of the lengthy description given by Hay, his only comment on the morphology

of the tip of the endopodite of the second pleopod was,

"inner ramus navicular, notched at the distal extremity." It is thus impossible to be certain about the identity of this taxon from the original description alone.

No mention is made in Hay's paper of type material,

but there is in the collections of the Illinois Natural

History Survey a collection of Asellus with the label,

"111. State Lab. Nat. Hist. Abingdon 111. O.P. Hay 1878

S.A. Forbes." Part of this label is in faded handwriting,

namely "Abingdon 111. O.P. Hay 1878", while the rest

is printed. These locality data correspond closely with

the locality data given by Hay for his original material

(1878, p. 92: "near Abingdon, Knox county, Illinois"), suggesting that the material was that used by

Hay in the preparation of his description. Further

evidence for this was kindly provided by Dr. J. D.

Unzicker, taxonomist at the Illinois Natural History

Survey, who wrote (personal communication, 5 June

1967):

I believe that the vial of A. militaris Hay, which I sent to

you, is the type series for this species because (1) the collecting data correspond with that given in the original description, (2) the vial was in a rack labelled 'check for type

material,' and (3) since Hay described this species in a paper

published in our Bulletin series the type would ordinarily be

deposited in our collection.

The material consisted of several detached peraeopoda

and a detached pleon, two ovigerous females, the front

half of a male specimen, one male specimen broken

into two halves, and one almost complete male specimen. The last specimen was fully dissected and examined by the present author; only the genital pleopoda

of the other damaged male were examined. The

examinations revealed that the material was conspecific

with lectotype material of A. intermedius and accordingly A. militaris may now be synonymized with this

species. The first and second pleopod of the least damaged male are illustrated in Figure 16. The material

remains in the collections of the Illinois Natural History Survey where it has no number and is referred

to as "INHS (uncataloged)" (J. D. Unzicker, personal

communication, 10 August 1967).

TYPE MATERIAL.—Lectotype, adult tf. Paralectotypes, 4cf cf and 6 ? $ . All material is deposited in the
26

V

FIGURE 16.—Asellus intermedius, least damaged male specimen collected from Abingdon, Illinois, in 1878 by O. P. Hay:

A, first pleopod; B, second pleopod; c, ventral surface of tip

of endopodite of second pleopod.

Illinois Natural History Survey, Urbana; the material

is not numbered, the reference is "INHS (uncataloged)." Data on original label reads: "Callahan Cr.

Cobden. 111. May 30, 1876 S.A. Forbes" and "Cotypes

Asellus intermedius Forbes."

DESCRIPTION OF LECTOTYPE.—Body: Length, 4.5

mm.

Head: Eyes large and distinct. Anterolateral lobes

not prominent.

First antenna: Tip of flagellum broken off, flagellum

at least 5-merous and reaching to point one-third distally along last segment of peduncle of second antenna.

All segments of peduncle about twice as long as wide;

first segment longest, second about three-quarters

length of first, and third about three-quarters length of

second.

Second antenna: Tip of flagellum broken off, but

length of antenna (2.5 mm) at least half (0.55) body

length. Flagellum at least 31-merous.

First peraeopod (Figure 17A) : Dactylus slightly

longer than palm of propodus and with 6 teethlike

spines on palmar edge and a long terminal claw. Propodus about 1.5 times as long as wide, almost subtriangular; palm with a large obtuse triangular projection about half width of opposing dactylus situated

near midpoint, 1 large toothlike spine at proximal end,

and a submarginal row of spines on inner and outer

surfaces.

First pleopod (Figure 17B) : Total length of appendage 1.10 times as long as second pleopod. Sympod subSMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

circular, about as wide as long; inner margin with 3

hooklike protuberances for coupling. Distal segment

subovate but distal margin somewhat truncate and

distal part of segment distinctly narrower than proximal part; maximum width slightly greater (0.57) than

half maximum length; distal margin and adjacent

part of outer lateral margin with 9 simple spines of

moderate length.

Second pleopod (Figures 17C-E) : Sympod subsquare, maximum length equal to maximum width.

Proximal segment of exopod with a single spine on

outer margin. Distal segment of exopod ovate with 2

short and 11 long setose spines. Endopod subrectangular, rather wide (maximum width about half maximum

length), and total length subequal to that of exopod;

conspicuous basal apophyses not present. Cannula

prominent, wide, as long as wide, and subequal in

length to caudal process. Caudal process prominent,

sclerotized, and terminated by a sharp point. Mesial

process not developed.

Uropod (Figures 18A,B) : Slightly shorter (0.77)

than telson. Peduncle about twice as long as greatest

width. Exopod as long as peduncle, endopod rather

longer (1.3); both rami have a number of long fine

spines distally, and numerous shorter and stronger

spines laterally.

PARTIAL DESCRIPTION OF FEMALE PARALECTOTYPE.—

"First" pleopod (Figure 18c) : Approximately trapezoidal in shape, almost (2.3) two and a half times as

long as maximum width. Distal margin and distal half

of outer margin with 7 long and 3 shorter finely plumose spines; a short simple spine occurs near inner

proximal angle.

MATERIAL EXAMINED.—ONTARIO: Humber

River,* York County, 4 c? c?, coll. Ontario P. & D.,

12.vi.1946 (NMC) ; Underwood Creek, Collingwood,

7c? d\ coll. J. B. Sprague, 2.iv.l955 (ROM); Rideau

River, 4c?c?, coll. Macoun Field Club, 30.iv.1955

(NMC); Rideau River, 2 c? c?, coll. E. L. Bousfield,

7.V.1955 (NMC); stream east of Houghton, 2c?c?,

coll. Ontario P. & D., 7.vi.l955 (NMC); Little Otter

Creek, 2c?c?, coll. Ontario P. & D., 9.vii.l955

(NMC); Rideau River, Id1, coll. Macoun Field Club,

12.V.1956 (NMC); Underwood Creek, Collingwood,

5c? c?, coll. J. B. Sprague, ll.viii.1956 (NMC); Frazer

Dontile Quarry Pond, Ottawa, 8 c? c?, coll. E. L. Bousfield, 29.ix.1956 (NMC); Taylor's Hill Quarry, Ottawa, 4c? c?> coll. E. L. Bousfield, 13.iv.1957 (NMC);

Taylor's Hill Quarry, Ottawa, 3 c? c?, coll. E. L. Bous-
NUMBER 49 27

FIGURE 17.—Asellus intermedius, lectotype: A, dactylus and palm of first peraeopod; B, first

pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces of tip of endopodite of

second pleopod.
28

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

H

FIGURE 18.—Asellus intermedius, A, B, lectotype; c, female paralectotype; D-K, extent of variation

in palm shape of male first peraeopod in nontype material: A, uropod and telson; B, uropod;

c, "first" pleopod; D, F, I, Ottawa, Ontario; E, Cook County, Illinois; o, Shawnee National

Forest, Illinois; H, Swedesburg, Iowa; j , Jefferson County, Kentucky; K, Lake Mendota,

Wisconsin.
NUMBER 49 29

field, 4.v. 1957 (NMC); Cooksville, 5<?<f, coll. D.

Barr, 5.iv.l962 (ROM); Cooksville, 14<? <f, 5.iv.l962

(ROM); Ottawa, 5 c? d, coll. E. L. Bousfield, 21.v.

1962 (NMC); Cooksville, 14c? cf, coll. D. Barr, 14.vii.

1962 (ROM).

ILLINOIS: Golconda, 3c?c?, coll. B. D. Burks,

12.iii.1940 (INHS); Palas Hills, Cook County,

ooc?c?, coll. L. Hubricht, 2.V.1941 (USNM); Lemont, Cook County, oo c? cf, coll. L. Hubricht, 3.v.

1941 (USNM); Galesburg, Knox County, oo c? cf,

coll. L. Hubricht, 4.V.1941 (USNM); Glendale, lc?,

coll. Messrs. Ross and Burks, 18.iv.1942 (INHS);

Carbondale, 4c?cf, coll. R. L. Lippson, 6.iv.l967;

Hutchin's Creek, Union County, 4c? <?, coll. R. L.

Lippson, 7.iv.l965.

INDIANA: Wabash River, New Harmony, lcf,

coll. U.S. Dept. Interior, 29.ix.1965; Wabash River,

New Harmony, lc?, coll. U.S. Dept. Interior, 2O.xii.

1965.

IOWA: Swedesburg, Henry County, oo <? c?, coll.

L. Hubricht, 24.iv.1942 (USNM).

KENTUCKY: Fish Pond Creek, Jefferson County,

3c?c?, coll. G. A. Cole, 21.iii.1954; Pennsylvania

Creek, Jefferson County, 7 c? cf, coll. G. A. Cole, 21.iii.

1954; Cedar Creek, Jefferson County, lc?, coll. G. A.

Cole, 28.iii.1954; Fern Creek, Jefferson County,

7c?<?> coll. G. A. Cole, 4.iv.l954; Beargrass Creek,

Jefferson County, 2 c? c?, coll. G. A. Cole, 25.iv.1954;

Pennsylvania Run, Jefferson County, 1 c?, coll. G. A.

Cole, 23.V.1954; Spring, Oldham County, 3 c? c?, coll.

G. A. Cole, 17.iv.1955 (NMC); Goose Creek,* Jefferson County, 4c? cf, coll. G. A. Cole, 4.V.1955; Ace.

59-173, Jefferson County, lcf, coll. G. A. Cole, 1957

(NMC).

MICHIGAN: Wolf Lake Hatchery, Van Buren

County, lcf, coll. R. L. Lippson, 25.xi. 1965.

MISSOURI: Meramec State Park, Franklin

County, ooc?cf, coll. L. Hubricht, 25.vii.1937

(USNM).

WISCONSIN: Lake Mendota, 32c? <?, coll. H. W.

Levi, September 1948 (CMZ); Lake Superior, Ashland, 6 c? cf, coll. E. L. Bousfield, 26.vi.1957 (NMC);

Lake Mendota, oo c? c?, coll. H. B. N. Hynes, 15.viii.

1962; Milwaukee River, lcf, coll. U.S. Dept. Interior, 23.viii.1962.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

localities listed above, together with the type locality,

are plotted in Figure 19. From this it can be seen that

A. intermedius occurs within a large area of east-

• A. intermedius

FIGURE 19.—Geographical distribution.

central United States and southern Ontario. Over a

part of its range it is sympatric with A. brevicauda

brevicauda, but its range is more extensive than that

of this species and it extends farther northward.

Most of the collections examined, as indicated by the

data on labels, had been obtained from creeks, streams,

or rivers, so that we may assume that A. intermedius

is characteristically associated with running waters.

Some of the collections, however, were from springs,

lakes, ditches, or ponds, and it is clear that A. intermedius is by no means restricted to running waters.

The ecology of this species has been intensively studied

by Ellis (1961); certainly for his correct identification

of the species is provided by his drawings of the male

genital pleopods (1961, figs. 2-4), which are undoubtedly those of A. intermedius.

FURTHER DESCRIPTION (cf)-—Body: The largest

cf examined was 16.0 mm long, and the smallest

4.0 mm.

First antenna: Flagellum 7- to 17-merous; flagellum

tip reaching to one-third along or to distal end of

the last segment of the peduncle of the second antenna; penultimate 2 to 4 (unusually 3) segments

bear aesthetascs.

Second antenna: Length 0.48 to 0.79 times that of

body. Flagellum 32- to 93-merous, depending upon

size.

Mouthparts: See Table 1.

First peraeopod: Dactylus with 4 to 14 teethlikc

spines on palmar margin; in general, these spines are
30

large and few in small specimens, and small and many

in large ones. The shape of the palm shown in Figure

17A (lectotype) occurs only in young specimens, and

the shapes typically encountered in large adult males

are more like those illustrated in Figures 18D-K, which

indicate the range of variation that occurs. Thus, the

large triangular structure near the midpoint of the

palm is always large and quite prominent (often sharply

pointed and occasionally toothlike), and the proximal

end of the palm is also usually produced outward, this

projection bearing a blunt wide tooth (very occasionally 2 such teeth) and beyond this 1 to 4 but usually 2

stout spines.

First pleopod: Total length of appendage 0.88 to

1.22 times as long as second pleopod. Inner margin

of sympod with 3 to 5 (usually 3 or 4) coupling hooks.

Maximum width of distal segment 0.36 to 0.71 times

maximum length; marginal spines few to numerous,

but always simple and of moderate length. The typical

shape of the distal segment is subovate; only a little

variation occurs.

Second pleopod: Maximum length of sympod from

1.0 to 1.2 times maximum width. Proximal segment of

exopod with 1 to 6 spines on outer margin; distal

segment with 7 to 23 plumose spines on margin. Inner

basal angle of endopod obtuse, sharply angled,

or produced into a small acutely pointed apophysis.

The main features of the morphology of the tip of the

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

endopod are constant, the principal variation occurring only in the shape and extent of development of

the caudal process; this may be rounded, pointed, or

have a terminal claw; it is frequently produced at

approximately right angles to the main body of the

endopod, and may in some cases have pointed basal

protuberances, although this is not usually so and is

found only in very large specimens. Figure 20 indicates

the range of variation in the morphology of the endopod tip. The typical morphology is as illustrated for

the lectotype (Figures 17D, E).

Uropod: See Table 2.

Asellus attenuatus Richardson

FIGURES 21, 22

Asellus attenuatus Richardson, 1900, p. 297.—Richardson,

1901, pp. 552-553, figs. 26-28.—Richardson, 1905, pp.

426-428, figs. 482-485.—Van Name, 1936, pp. 461-462,

fig. 289.

The name Asellus attenuatus was first published as

part of an identification key for North American Asellidae, and the only distinguishing characters mentioned

were confined to the uropoda and propodus of the first

peraeopod (sex unstated) (Richardson, 1900). The

description sensu stricto was not published until the

following year (Richardson, 1901). This, while more

FIGURE 20.—Asellus intermedius, extent of variation in morphology of endopod tip of male second pleopod: A, E, Oldham County, Kentucky; B, D, Jefferson County, Kentucky; c, Meramec

State Park, Franklin County, Missouri; F, Lake Mendota, Wisconsin; o, Wabash River, Indiana;

H, Collingwood, Ontario.
NUMBER 49 31

complete and accompanied by some drawings, is insufficiently detailed to enable adequate identification

of Richardson's taxon; no mention is made, for example, of the form of any pleopoda. It is not surprising,

therefore, that no further material of this species has

been identified since the original type collection was

made (1899). Some additional descriptive details concerning the female genital pleopoda and the propodus

of the male first peraeopod were given by Richardson

in 1905, but these details likewise are insufficient to

clarify the species identity.

Fortunately, type material of A. attenuates was set

aside by Richardson, this being noted in her publications (1901, 1905) as: "Type [sic].—Cat. No. 23910,

U.S.N.M." Through the courtesy of Dr. T. E. Bowman, National Museum of Natural History, I have been

able to reexamine this material. It was contained in two

tubes in a jar labeled "23910 Asellus attenuates." One

tube contained 2 specimens (1 o*, 1 nonovigerous $ )

and the other 100 specimens (9cf cf, 90 nonovigerous

$ $, 1 juvenile). The material in the first tube had

obviously been withdrawn from the larger collection

at some time, for there is a note that it had been "given

to Hubricht in exchange and returned by Hubricht as

gift." Several labels were in the second tube, of which

the significant one read: "United States National

Museum 23910 Asellus attenuates Richardson Washington Ditch, Dismal Swamp, Va. June 9, 1899 Wm.

Palmer and Paul Bartsch for the Museum. Type 106

id. H. Richardson Ace. No. 35186." Two microvials

were also present in the jar, one containing the damaged posterior half of a specimen and the other a

detached peraeopod and maxilliped. All specimens

were damaged and no single complete male was present; the least damaged male lacked only uropoda, while

all remaining males lacked at least their second antennae. Of the females present only five possessed attached

second antennae. The least damaged male has been

designated lectotype, the remaining specimens as

paralectotypes.

TYPE MATERIAL.—Lectotype, adult d1- Paralectotypes, 9cf cT, 91 nonovigerous ? ? , 1 juvenile. All

material is deposited in the National Museum of

Natural History, USNM 23910.

DESCRIPTION OF LECTOTYPE.—Body: Length, 9.5

mm.

Head: Eyes large and distinct; posterolateral lobe

not prominent but bearing a single long and robust

spine.

First antenna: Flagellum 14-merous and tip reaching to midpoint of last segment of peduncle of second

antenna; penultimate 2 segments bear aesthetascs.

Flagellum subequal in length to peduncle. First and

second segments of peduncle subequal in length; third

segment about two-thirds length of second. First segment of peduncle about twice as long as wide; second

and third each 4 times as long as wide.

Second antenna: Length (10.5 mm) slightly longer

(1.11) than body. Flagellum 82-merous. First, second,

and third segments of peduncle stout, about twice as

wide as long; fourth segment twice as long as first

three combined, 4 times as long as wide; fifth segment

about 1.5 times as long as fourth, about 8 times as

long as wide.

Mouthparts: See Table 1.

First peraeopod (Figure 21A) : Dactylus about 1.5

times longer than palm, with 10 teethlike spines on

palmar margin and a distinct terminal claw. Propodus

slightly less than twice as long as wide, subovate; palm

with a single low blunt triangular projection near midpoint, a very long and strong tooth at proximal end, and

numerous short to long submarginal spines.

First pleopod (Figure 21B) : Total length of appendage only three-quarters length of second pleopod.

The division of the appendage into proximal and distal

segments is incomplete so that it appears somewhat

dumbell-shaped; the basal portion has 3 hooklike

coupling protuberances on its inner margin, and the

subovate distal portion has 11 short, simple (apparently) spines on its distal margin.

Second pleopod (Figures 21C,E) : Sympod subovate,

maximum length 1.44 times maximum width. Proximal segment of exopod with a single spine on outer

margin. Distal segment of exopod with 1 short and

simple spine and 17 long plumose spines on margin.

Endopod rather narrow, more or less straight in long

axis, and about 3.5 times central width; endopod threefifths total length of exopod, but distinctly shorter

(0.72) than distal segment of exopod; inner and outer

basal apophyses present but not well developed. Cannula long and tubular and extending beyond caudal

process. Mesial process long, subequal in length to cannula, sclerotized* and ending in a sharp point. Caudal

process present but not well developed and more or less

rounded in outline with no associated hooks or spines.

Uropod: Missing (seebelow).

PARTIAL DESCRIPTION OF MALE PARALECTOTYPE.—

Uropod (Figure 2IF) : Same length as telson. Peduncle

378-615 O - 70 - 3
32

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 21.—Asellus attenuates, A-C, E, lectotype; D, F, male paralectotype: A, dactylus and

propodus of first peraeopod; B, first pleopod; c, second pleopod; D, E, respectively dorsal and

ventral surfaces of tip of endopodite of second pleopod; F, uropod.
NUMBER 49 33

about 3 times as long as greatest width with several

marginal spines. Exopod and endopod respectively 1.2

and 1.3 times peduncle length; both rami narrow and

with a small group of very long fine spines at distal

tip as well as several stout marginal spines.

PARTIAL DESCRIPTION OF FEMALE PARALECTOTYPE.—

Body: Length, 11.0 mm; maximum width, 4.5 mm.

Second antenna: Length (13.0 mm) distinctly

greater (1.18) than body length.

First peraeopod (Figures 22A,B) : Relatively slender

and not subchelate. Dactylus about as long as palm of

propodus with 12 teethlike spines on margin and a

larger terminal spine. Propodus subovate, about twice

as long as greatest width. Carpus triangular, small.

Merus sub triangular, about as wide as long, with 2 long

and strong spines at anterodistal angle. Ischium subrectangular, not quite twice as long as merus, twice as

long as wide. Basis subtrapezoidal, about 1.5 times as

long as ischium, twice as long as wide.

"First" pleopod (Figure 22c): Shape almost subrectangular, distal width slightly greater than proximal width, length 2.5 times maximum width. Distal

margin with 17 long plumose spines and a single short

simple spine at outer distal angle.

DISCUSSION.—The damaged condition of the type

material, and especially the presence of only a few

specimens with attached second antennae, is rather unfortunate, for it appears that the ratio of the length

of the second antennae to the body length constitutes

one of the salient characters of this species, as indicated

by Richardson's name for it. In the five females with

attached second antennae, the ratio—length of second

antenna/body length—varied from 0.94 to 1.31.

The paucity of male specimens is also most unfortunate for it precludes the determination of the extent

of phenotypic variation in the genital pleopoda and

other critical parts of males of this species. At first it

was thought that the incomplete division and relatively

small size of the first pleopod was perhaps an aberration of the sort known to occur occasionally in single

specimens of Asellus (cf. Williams, 1962a), but the

same configuration was displayed by the first pleopod

of a male paralectotype. At all events, study of further

material is certainly needed to indicate the extent of

B

FIGURE 22.—Asellus attenuates, female paralectotype: A, first peraeopod; B, dactylus and

propodus of first peraeopod; c, "first" pleopod.

378-615 O - 70 - 4
34

morphological variation in A. attenuatus. It must be

recorded that no such material was encountered during the present revision, indicating perhaps that A.

attenuatus has a restricted range of distribution. The

only Dismal Swamp in Virginia known to the writer

lies in the extreme southeastern corner of the state just

west of Portsmouth (Figure 30).

In the morphology of the tip of the endopod of the

second male pleopod, A. attenuatus closely approaches

A. racovitzai, and the taxa may perhaps prove to be

no more than subspecifically separate. However, the

lack of a well-developed caudal process and the somewhat more elongated nature of the cannula and mesial

process, combined with other differences between the

taxa, indicate that until further study of material of

Richardson's taxon has been made it is appropriate

at present to retain specific status for it. The other

differences, as indicated by the study of lectotype material, are that in both sexes of A. attenuatus the second

antennae are longer (almost as long as or longer than

the body), and that in males the first pleopod is significantly shorter than the second and is incompletely

divided into a proximal portion and a subovate distal

portion, and the endopod of the second pleopod is

distinctly shorter than the distal segment of the corresponding exopod. Other apparent differences, such as

those in the proportions of the antennal segments and

the shape and armature of the first male peraeopod

and the uropod, are perhaps less significant for these

appendages in Asellus are known to be rather variable

in structure.

Asellus dentadactylus Mackin and Hubricht

FIGURE 23

Asellus dentadactylus Mackin and Hubricht, 1938, pp. 629-

630, figs. 3-6, 8.—Van Name, 1940, pp. 127-128, fig. 20.

The original description of A. dentadacytylus is certainly sufficient to allow identification of this species

with considerable confidence, as the morphology of the

tip of the endopodite of the male second pleopod is

described in some detail and figured. The accuracy

of the original description and figures was checked

by reexamination of the type material deposited by

Mackin and Hubricht in the United States National

Museum. This material consisted of specimens

distributed within two jars, one containing 24 specimens and labeled both "paratypes" and "cotypes," the

other containing 8 specimens and labeled only "coSMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

types." From the second jar one adult male has been

designated the lectotype; the remaining 4 o* o* and

3 ovigerous 9 9 in this jar, and all the specimens

in the other jar, have been designated paralectotypes.

A label in the second jar reads: "A 2659 April 11, 1936

Asellus dentadactylus Mackin and Hubricht Small

creek, /2 mile S. of Locust Cottage, Jefferson Co.,

Arkansas Leslie Hubricht coll. Cotype. Cat. No. 74841

USNM." Other labels in both jars gave the same

information.

Although Mackin and Hubricht's description supplies the more significant details concerning the morphology of A. dentadactylus, their description is incomplete, and at least with regard to the fine structure

of the endopodite tip of the male second pleopod

several differences are apparent between their drawings and my own based on the lectotype. Furthermore,

it is not possible to discern from their drawing (fig. 4)

the relationships of the various processes surrounding

the cannula, nor indeed to be certain of the position

of the cannula itself. Concerning the morphology of

the endopodite tip Mackin and Hubricht state only

(1938, p. 629), "truncate tip with wide opening." For

these reasons, a description of the lectotype is given

below. Van Name (1940) simply repeated the descriptive details given by Mackin and Hubricht (1938).

DESCRIPTION OF LECTOTYPE (O*)-—Body: Length,

7.5 mm; maximum width, 2.0 mm.

Head: Eyes distinct.

First antenna: Flagellum 10-merous and tip reaching to midpoint of last segment of peduncle of second

antenna. Flagellum three-quarters length of peduncle.

First segment of peduncle about three-quarters length

of second, second about twice as long as third. First

segment about twice as long as wide, second and third

each about 4 times as long as wide.

Second antenna: Length (6.0 mm) four-fifths body

length. Flagellum about 56-merous.

Mouthparts: See Table 1.

First peraeopod (Figure 23A) : Dactylus subequal

in length to palm, with 9 small denticles on palmar

margin and a large terminal claw. Propodus 1.3 times

as long as wide, subtriangular; palm with a large

acutely pointed triangular projection near midpoint,

one toothlike spine and 2 stout spines at proximal end,

and numerous short to long submarginal spines.

First pleopod (Figure 23B) : Total length of appendage distinctly longer (1.35) than second pleopod.

Sympod subrectangular, about 1.5 times as long as
NUMBER 49 35

FIGURE 23.—Asellus dentadactylus, A-F, lectotype; o, female paralectotype: A, dactylus and

propodus of first peraeopod; B, first pleopod; c, second pleopod; D, E, respectively dorsal and

ventral surfaces of tip of endopodite of second pleopod; F, uropod; o, "first" pleopod.
36

wide; inner margin with 5 hooklike protuberances for

coupling. Distal segment also subrectangular, but

gently curved outward so that the outer lateral margin

is distinctly concave and the inner lateral margin convex; proximal width slightly greater than distal width;

maximum width slightly less (0.46) than half maximum length; distal margin bearing 6 long sparsely

setose spines and 8 shorter simple spines somewhat

irregularly arranged; inner proximal angle with a short

simple spine.

Second pleopod (Figures 23C-E) : Sympod subquadrate, maximum length only slightly greater (1.2) than

maximum width; medial and lateral margins more or

less straight. Proximal segment of exopod cupulate,

outer margin with 5 short simple spines. Distal segment of exopodite subovate, about 1.5 times as long

as wide, and with 16 long plumose spines on outer

and distal margins and several fine short spines on

inner margin. Endopod about as long as exopod; prominent inner and outer apophyses occur basally. Cannula short and narrow. Ventral groove short. Mesial

process large and well developed, bifid, and extending

beyond cannula. Lateral process not prominent. Caudal

process wide, not protruding beyond cannula, and

irregularly dentate.

Fourth pleopod: Six plumose spines on outer distal

margin in addition to those spines occurring along outer

proximal margin.

Uropod (Figure 23F) : As long as telson. Peduncle

about twice as long as greatest width. Exopod twothirds (0.63) length of peduncle, endopod almost as

long (0.91) as peduncle; both rami have a number

of long fine spines distally, and numerous shorter and

stronger ones laterally.

PARTIAL DESCRIPTION OF FEMALE PARALECTOTYPE.—

First peraeopod: General shape and setation similar

to that described for a female paralectotype of A.

attenuatus but propodus has a single moderately long

and strong toothlike spine near proximal end of palm.

Palmar margin of dactylus with 4 teethlike spines.

"First" pleopod (Figure 23G) : Shape subtriangular,

but outer margin convex with 14 long plumose spines

on distal half.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—No

further material of this species was encountered during the present investigation, and I cannot add therefore to the two localities from which the species has

hitherto been recorded (Mackin and Hubricht, 1938).

The known localities are in Arkansas (type locality)

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

and Louisiana (Natchitoches Parish, 2 miles south of

Saline); their positions are indicated in Figure 7.

Concerning the ecology of this species, it can only

be said that specimens have been taken from a small

creek, and from among dead leaves in a small creek

below an artificial pond (Mackin and Hubricht, 1938).

Asellus montanus Mackin and Hubricht

FIGURE 24

Asellus montanus Mackin and Hubricht, 1938, pp. 630-631,

figs. 1, 2, 7, 9, 10.—Van Name, 1940, pp. 126-127, fig. 19.

Like A. dentadactylus discussed above, the original

description of A. montanus is certainly sufficient to

allow specific identification with considerable confidence; the morphology of the tip of the endopodite

of the male second pleopod of this species also is described in some detail and figured. The accuracy of the

original description and figures is supported by a reexamination of the type material deposited by Mackin

and Hubricht in the United States National Museum.

This material consisted of 14 specimens in a jar with

the label: "United States National Museum 74842

Asellus montanus Creek, Y-city, 4 miles S. of Boles,

Scott Co., Ark. L. Hubricht (coll. & don.) April 27,

1936 id. Mackin and Hubricht Ace. No. 145424 Cotypes." The specimens were actually in a tube inside

the jar and this tube had its own label which, however, gave the same information as the one in the jar.

The 14 specimens consisted of 7 o" o*} 5 ovigerous ? $ ,

and 2 nonovigerous ? $ . All males were damaged to

a greater or lesser extent; the least damaged male was

designated the lectotype and all other material was

designated paralectotypes.

As was the case for A. dentadactylus, although

Mackin and Hubricht's description gives the pertinent details concerning the morphology of A. montanus, it is incomplete, and with regard to the fine

structure of the tip of the endopod of the male second

pleopod minor differences are again apparent between

their drawing and my own based on the lectotype. For

these reasons a description of the lectotype is given

below. Van Name (1940) simply repeated the descriptive details given by Mackin and Hubricht (1938).

DESCRIPTION OF LECTOTYPE (o*) •—Descriptive details are omitted when these refer to parts of the body

that are similar in construction in A. communis (neo-
NUMBER 49 37

FIGURE 24.—Asettus montanus, A-F, lectotype; o, female paralectotype: A, distal segments of

first peraeopod; B, first pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces

of tip of endopodite of second pleopod; F, uropod; o, "first" pleopod.
38

type), or, where indicated, A. dentadactylus (lectotype).

Body: Length, 11.5 mm; maximum width, 2.5 mm.

Head: Eyes relatively large and distinct.

First antenna: Flagellum 13-merous. Otherwise

similar to A. dentadactylus.

Second antenna: Length (9.0 mm) four-fifths body

length. Flagellum 94-merous and about twice length

of peduncle. Fourth segment of peduncle about 1.5

times as long as first three segments combined, 4 times

as long as wide; fifth segment about 1.5 times length

of fourth, 6 times as long as wide.

Mouthparts: See Table 1.

First peraeopod (Figure 24A) : Dactylus slightly

shorter than palm, lacking spines or denticles on palmar margin but with a short and rather blunt terminal

claw. Propodus 1.5 times as long as wide, subquadrate;

palm with a large acutely pointed triangular projection near midpoint, 2 small but stout toothlike spines

at proximal end, and numerous short to long submarginal spines.

Second to seventh peraeopoda: Segments generally

more elongated than as described for A. communis,

and dactyli bear fewer teethlike marginal spines. The

proportions of the segments to each other in a given

peraeopod are nevertheless similar to those described

for A. communis.

First pleopod (Figure 24B) : Total length of appendage distinctly (1.32) longer than second pleopod.

Sympod subquadrate, about as long as wide; inner

margin with 5 hooklike protuberances for coupling.

Distal segment broadly ovate, widest about two-thirds

toward distal margin; maximum width half maximum

length; numerous short and simple spines occur on the

distal margin and the distal half of the outer margin,

and in addition 4 long plumose spines are present on

the distal margin.

Second pleopod (Figures 24C-E) : Sympod subquadrate, maximum length only slightly greater (1.2)

than maximum width; medial and lateral margins

more or less straight. Proximal segment of exopod irregularly subtriangular, marginal spines absent. Distal

segment of exopod subovate, twice as long as wide,

with 11 long plumose spines on outer and distal margins, and a row of very fine short spines on inner margin. Endopod a little longer (1.17) than exopod. The

body and associated structures of the endopod are arranged in a spiral fashion; thus, the main body appears to be twisted through 180° so that the terminal

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

groove, which lies ventrally in other species, here lies

dorsally. The terminal processes are subject to even

more twisting and appear to coil at least 1.5 times. The

actual processes involved in the coiling are difficult to

discern, but it appears that the caudal process is not

involved (and is not developed) and the lateral one is.

The cannula is not visible. Basally, the endopod has

an indistinct inner apophysis and a distinct outer rightangled apophysis.

Uropod (Figure 24F) : Slightly longer (1.1) than

telson. Peduncle about 3 times as long as greatest

width. Exopod slender, about half (0.46) length of

peduncle; endopod rather spathulate, four-fifths

length of peduncle; both rami have a number of long

fine spines distally (the endopod more than the exopod), and a few short ones laterally.

PARTIAL DESCRIPTION OF FEMALE PARALECTOTYPE.—

First peraeopod: General shape and setation similar to

that described for a female paralectotype of A. attenuatus but propodus has 2 strong teethlike spines

near proximal end of palm, one moderately long and

one shorter. Palmar margin of dactylus with 2 teethlike spines.

"First" pleopod (Figure 24o): Triangular, distal

two-thirds of outer margin more or less straight and

with 1 short simple spine and 13 long plumose spines.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—No

further material of this species was encountered during

the present study, and I cannot add therefore to the

5 localities from which the species has been recorded

(Mackin and Hubricht, 1938). The known localities

are in Arkansas (type locality, and near Minturn)

and Oklahoma (two localities in Leflore County and

one in Latimer County); their positions are indicated in

Figure 7. Mackin and Hubricht (1938) record the

species from a roadside slough and creeks or streams.

AseUus kenki Bowman

FIGURE 25, 26

Asellus kenki Bowman, 1967, pp. 131-140, figs. 1-44.

Asellus kenki was recently described by Bowman

(1967) in what is undoubtedly the best description of

a North American epigean species of Asellus that has

appeared. I need add nothing to this description and

there is certainly no point in reproducing it in entirety

here. The species is characterized principally by the

shape of the uropoda, the configuration of the first and
NUMBER 49 39

FIGURE 25.—Asellus kenki, male: A, first pleopod; B, distal margin of first pleopod; c, second

pleopod; D, E, respectively dorsal ( = posterior) and ventral ( = anterior) surfaces of tip of

endopodite of second pleopod. From Bowman (1967) with permission.

second pleopoda in males, and above all by the morphology of the tip of the endopodite of the male second

pleopod. For comprehensiveness and convenience,

Bowman's description of these features is reproduced

here, and they are again illustrated (Figures 25, 26).

The figures have been prepared entirely by selection

from the drawings given by Bowman.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult d, USNM 119808. Paratypes: numerous other

specimens from the type locality, USNM. Type locality: spring-fed pool located 0.91 km SSW of the

Nature Center, Rock Creek Park, Washington, D.C.

PARTIAL DESCRIPTION (reproduced from Bowman,

1967).—Body: Moderately small, largest male 14 mm

in length, but most mature males considerably shorter;

ovigerous females reaching 7-8 mm.
40

FIGURE 26.—Asellus kenki, right uropod or both uropoda and

telson, dorsal views: A, 3.5 mm male; B, 5.0 mm male; c, 6.5

mm male; D, 8.2 mm male; E, 6.5 mm ovigcrous female; F,

13.0 mm male. From Bowman (1967) with permission.

Eyes: Small, slightly longer than broad, composed of

few facets.

Second antenna: 0.75 to 0.8 as long as body (excluding uropoda); flagellum about 70-merous.

Male first pleopod (Figures 25A,B) : Peduncle

three-quarters as long as exopod, with 3 or 4 coupling

spines. Exopod about 1.6 times longer than wide, distal part with concave lateral margin, bent laterad, and

bearing 5 long plumose setae on broad apex and several

shorter setae proximal to apical setae; distal part of

lateral margin with row of setules.

Male second pleopod (Figures 25C-E) : Peduncle

about one-third longer than wide, with about 5 setae

on distomedial margin and 5 short setae on posterior

surface near proximolateral margin. Exopod about

three-quarters as long as peduncle; proximal segment

cupulate, inserted into peduncle by truncate base with

heavily sclerotized lateral margin, bearing rectangular

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

flap on posterior surface, distal part of segment widening into rounded lobes on each side; lateral lobe with

sclerotized margin continuous with that of base, bearing 4 or 5 short setae; medial lobe produced beyond

insertion of distal segment, margin sclerotized. Distal

segment of exopod narrowing apically, armed with

plumose setae on lateral margin and distal third of

medial margin; proximal third of medial margin with

broad sclerotization. Endopod shorter than exopod,

with well-developed medial apophysis in proximal

part; distal to apophysis endopod curves strongly

laterad and ends in 5 processes: a straight rounded

lateral process, a medial process consisting of a lobe

overriding medial process and a rugose lobe posterior

and proximal to it, a medially curving cannular posterior to lateral process, and a broadly rounded posterior process [? caudal process] with a few rugosities

[Bowman uses the terms anterior and posterior in place

of respectively ventral and dorsal; the latter terms are

to be preferred as they are a more accurate description

of the position of the appendages in life].

Uropod (Figures 26A-F) : In females and immature

males, exopod about 1.1 times longer than peduncle;

endopod 1.1 times longer than exopod; both rami

linear, armed with spines on margins and at apex.

Uropod of mature male modified: exopod shorter than

peduncle; endopod spatulate, much longer and broader

than exopod.

MATERIAL EXAMINED.—MARYLAND: Montgomery County, 3o"cf, 3 ovigerous? ? , 1 nonovigerous

? , col. G.R. Shoemaker, 28.V.1916 (USNM).

In all fundamental details this material agreed closely

with Bowman's description of A. kenki. However, the

second antennae of one specimen were as long as the

body, the first pleopod (male) lacked a notch on the

inner edge of the distal segment and more coupling

protuberances (6) were on the proximal segment, and

the broadly rounded posterior or dorsal process at the

tip of the endopodite of the second pleopod was by

no means as prominent as suggested by Bowman's

drawings.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—Bowman gives a long list of material examined by him.

This had been collected from various localities in the

District of Columbia, Maryland, Pennsylvania, and

Virginia. The additional material seen by me is therefore well within the known range of distribution of

this species. As a basis for comparison with the geographical distribution of other North American species
NUMBER 49 41

FIGURE 27.—Geographical distribution.

of Asellus, Bowman's records and the single new one

are combined in Figure 27. The figure indicates the

restriction of the species to a relatively small region in

the central part of the far eastern side of the United

States.

According to Bowman (1967), A. kenki is an inhabitant of springs and spring-fed streams and is not

found in large streams and ponds within its range of

distribution. The associated fauna in the type locality

and some further ecological remarks are also noted by

Bowman.

Asellus aquaticus (Linnaeus)

FIGURE 28

Oniscus aquaticus Linnaeus, 1758, p. 637.—Otho Fabricius,

1780, p. 251.

Asellus aquaticus (L.).—Geoffrey St. Hilaire, 1764, p. 672.—

Saw, 1899, p. 97.—Racovitza, 1919, pp. 31-41, figs. 1-6.—

Richardson, 1905, pp. 428-431, fig. 486.—Stephensen,

1917, pp. 239-240.—Van Name, 1936, pp. 458-459, fig.

287.—Birstein, 1951, pp. 57-60, figs. 18-26.—Williams,

1962b, pp. 78-80.

Asellus vulgaris Latreille, 1803, p. 359.—Not Gould, 1841, p.

337.

Asellus gronlandicus? Kreyer, 1838, p. 318—Not Packard,

1867, p. 296.—Hansen, 1888, p. 190.

A complete synonymy for Asellus aquaticus would be

extremely long and complex and is not needed here, as

this species is probably restricted to the Palaearctic and

more complete synonymies have been given elsewhere

(e.g., Bovallius, 1886; Gruner, 1965). The synonymies

and references given above cover the orginal description and generic transference, the most pertinent references to A. aquaticus in the Palaearctic, and all

references to the synonyms of the species in North

America.

Asellus aquaticus was first indicated as present in

North America by Otho Fabricius (1780) who recorded it from Greenland. A further Greenland record

was given by Kreyer (1838) who recorded what he said

was undoubtedly the same species as Fabricius, but who

tentatively gave it separate specific status (as A. gronlandicus), a separation of which Hansen (1888), who

referred to it as "A. grenlandicus" had great doubts.

Richardson (1905) gave yet another record of A.

aquaticus in Greenland based upon material sent her

by the Museum of Comparative Zoology at Harvard

and labeled "Asellus gronlandicus."

Stephensen (1917) summarized the old records of

A. aquaticus in Greenland, and on the basis of his

summary and a personal communication from Dr.

Ulrich Roen, who had examined many hundreds of

freshwater localities in Greenland, I came to the conclusion (Williams, 1962b) that A. aquaticus is probably absent from Greenland. It is now necessary to add,

however, that a collection of material in the Museum

of Comparative Zoology at Harvard and clearly

labeled "M C Z Greenland Asellus aquaticus (Linnaeus)" on examination proved to contain material

which is probably A. aquaticus. The material consisted

of two specimens, both of which had dried out and

were in very bad condition. Gentle warming in alcohol

helped to soften them, but unfortunately one was still

completely unrecognizable at the species level. The

other, however, though impossible to identify definitively to species, could be seen to possess many features

characteristic of A. aquaticus. The most important

features are indicated in Figures 28A-C. From these it

can be seen that the specimen (a male) possessed a

prominent basal spur on the endopod of the second

pleopod (a feature possessed by no other epigean species recorded from North America), its first pleopod

can reasonably be reconstructed to a shape similar to

that of the first pleopod of A. aquaticus, and the propodus of its first peraeopod lacked a triangular projection near the midpoint of its palm. This material would

seem to be that examined by Richardson in 1905, and

my reexamination of it, therefore, gives support to her

identification as A. aquaticus.

The reexamination although solving partly one of

the problems associated with records of A. aquaticus in
42

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 28.—A stilus ?aquaticus, least damaged specimen (male) labeled "MCZ Greenland

Asellus aquaticus (Linnaeus)": A, palm of propodus and part of dactylus of first peraeopod; B,

first pleopod; c, second pleopod.

North America, namely reliable identification, does not

really clarify the present status of the species. The conclusion remains, it seems reasonable to state, that A.

aquaticus is not present in Greenland, a conclusion

with which Dr. Reen (personal communication, 7 June

1967), who has examined many further Greenland

localities since his original communication to me (see

Reen, 1962), still agrees. The specimens belonging

to the Museum of Comparative Zoology may, as suggested by Roen (in Williams, 1962b, p. 80) for

older records, have come originally from Denmark in

ships' water tanks, have been introduced temporarily

to suitable waters in Greenland near ship bases there,

and then have been collected as a "native" species.

It should be added that A. aquaticus has not been

recorded for North America outside Greenland, and

no further material has been encountered during the

present study of North American collections. Packard's

(1867) record of A. aquaticus from Labrador related

in fact to a terrestial isopod (Johansen, 1926).

The name Asellus vulgaris advanced by Latreille in

1803 for European material has been consistently synonymized with A. aquaticus (see, for example, Birstein,

1951; Gruner, 1965), and there is little to gainsay this.

Gould recorded a taxon he referred to as "A. vulgaris?

Latr." from Massachusetts in 1841, but as he says only

that is was common, was larger than the two species

described by Say [1818, A. communis and A. lineatus

(=Lirceus lineatus) ], and that he could find no differences from "the foreign species," we are left in considerable doubt as to identity of his specimens. In view

of the almost certain absence of A. aquaticus from

North America apart from Greenland, it is most unlikely that Gould's specimens were A. aquaticus.

Through the courtesy of Dr. H. W. Levi and Miss A.

B. Bliss, I have examined all available material of

Asellus in the Museum of Comparative Zoology, the

principal institution for the deposition of zoological

material in Massachusetts, and did not encounter any

material that could have been seen by Gould. Gould's

species has been synonymized with A. communis by

Richardson (1905) and Van Name (1936), but neither

author advanced reasons for this synonymy. The identity of the species recorded by Gould must remain

unknown.

Asellus racovitzai, new species

Asellus communis Say.—Racovitza, 1920, pp. 79-95, figs.

52-73.

As indicated under A. communis, Racovitza (1920)

described fully a species, which he took to be A. com-
NUMBER 49 43

munis Say, on the basis of three specimens (2o*o"}

1 $ ) from the Potomac River, Virginia, a locality

some 125 miles from the place where we may presume

Say had collected his material of A. communis. Racovitza's assumption of conspecificity between this material

and A. communis appears to have been quite arbitrary.

As the neotype of A. communis is quite clearly a different species from the one described by Racovitza, a new

name now needs to be applied to the species described

by him. It is appropriate that this be A. racovitzai in

his honor.

There is no doubt of the identity of A. racovitzai or

of the fact that it is a species quite distinct from A.

communis; not only is Racovitza's description very

complete, but also there is still in existence the remains

of the collection from whence came the three specimens

sent to him. Examination of this confirmed the accuracy of his description.

During the examination of material referable to

A. racovitzai, it became clear that two minor taxa were

involved, one widespread in northeastern United

States and southeastern Canada but occurring also in

British Columbia and Washington State (see below),

and one confined to a smaller region (Georgia and

Florida) in southeastern United States. The differences

between these two taxa are considered to be of subspecific value. The taxon first described by Racovitza

is regarded as the nominate subspecies and its further

description given here and the selection of type material for it is based upon the remains of the collection

in the United States National Museum from which

Racovitza was sent 3 specimens; the taxon known thus

far only from the southeast United States is given the

name A. racovitzai australis.

Asettus racovitzai racovitzai, new subspecies

FIGURES 29, 31, 32

Asellus communis Say—Racovitza, 1920, pp. 79-95, figs. 52-

73.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult cf, USNM 122066. Allotype: adult nonovigerous ? , USNM 122067. Paratypes: 18 dd, 2 nonovigerous and 2 ovigerous $ $, USNM 122068. Type

locality (according to data on original label in type

collection) : edge of Potomac River just below aqueduct bridge [Washington, D.C.], Virginia side. The

collection was made 15 March 1896 by W. P. Hay.

DESCRIPTION OF HOLOTYPE.—Body: Length, 13.5

mm; greatest width, 5.0 mm.

Head: Eyes large and distinct.

First antenna: Flagellum 15-merous and tip reaching to point about two-thirds distally along last segment of peduncle of second antenna; penultimate 2

segments bear aesthetascs. First and third segments of

peduncle subequal in length, and about two-thirds

length of second segment. First peduncle segment about

1.5 times as long as wide; second and third segments

respectively 4 and 3 times as long as wide.

Second antenna: Length (8.0 mm) about threefifths (0.59) body length. Flagellum 67-merous.

First peraeopod (Figure 29A) : Propodus 1.3 times

as long as wide, almost sub triangular; palm with a

single large triangular projection about 1.5 times width

of opposing dactylus and about twice as long as basal

width situated near midpoint, a small projection between larger projection and point of attachment of

dactylus, 2 large and 1 small teethlike spines at proximal end, and a submarginal row of spines on inner

and outer surfaces.

First pleopod (Figure 29B) : Total length of appendage 1.1 times as long as second pleopod. Sympod

subrectangular, about three-fourths as wide as long;

inner margin with 2 hooklike protuberances for coupling. Distal segment also subrectangular, but distal

width less than proximal width; outer margin not concave; twice as long as wide and almost twice as long

as sympod; distal margin and distal two-thirds of

outer margin bearing numerous short to moderately

long simple spines; inner proximal angle with single

spine.

Second pleopod (Figures 29C-E) : Sympod subsquare, with 2 simple spines near inner distal angle.

Proximal segment of exopod with 6 simple spines on

outer margin. Distal segment of exopod ovate with 22

long plumose spines and 3 short simple spines marginally, some minute simple spines on inner margin,

and groups of fine setae on surface of segment near

inner margin. Endopod narrow, more or less straight

in long axis, and about 3 times as long as greatest

width; endopod about three-fourths total length of

exopod and also of sympod but slightly longer (1.1)

than distal segment of exopod; inner and outer apophyses occur basally. Cannula triangular in shape,

distal width about half basal width, and not reaching

beyond caudal process. Ventral groove wide and

prominent. Mesial process well developed, sclerotized,

acutely pointed, and almost as long as cannula. Lateral

process not developed. Caudal process large, ending

in prominent apex distally and bearing several groups
44

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 29.—Asellus racovitzai racovitzai, bolotype: A, dactylus and propodus of first peraeopod;

B, first pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces of tip of endopodite of second pleopod; F, uropod.
NUMBER 49 45

of 3 to 5 fine simple spines on dorsal surface, some of

which are visible on outer lateral margin.

Uropod (Figure 29F) : About the same length as

telson. Peduncle about 1.5 times as long as greatest

width with many marginal spines. Exopod almost as

long (0.83) as peduncle; endopod slightly longer (1.1)

than peduncle and about 3 times as long as wide.

PARTIAL DESCRIPTION OF ALLOTYPE ( $ ).—First

peraeopod: General shape and setation similar to that

described for a female paralectotype of A. attenuatus.

Palmar margin of dactylus with 8 teethlike spines.

"First" pleopod: Shape similar to that described for

a female paralectotype of A. intermedius, but distal

margin and distal half of outer margin with 16 finely

plumose spines, and inner proximal angle with 2 short

simple spines.

MATERIAL EXAMINED.—GREAT LAKES: Lake

Erie: Sta. G-25, 3 cfcf, coll. J. Hiltunen, 7.ix.l963;

Sta. 145,28 meters, 6cf cf, coll. J. Hiltunen, 10.ix.1963;

70 localities at various depths from 10.5-30 meters,

250 cfcf, all coll. Great Lakes Institute, 3.vi. 1963-16.

xi.1965 (GLI). Lake Huron: 4 localities at various

depths from 21-28 meters, 86* cf, all coll. Great Lakes

Institute, 16-24.xi.1964 (GLI). Lake Ontario: USB

GF Sta. 35, cocf cf, coll. J. Hiltunen, 16.ix.1964; 25

localities at various depths from 20-42 meters, 63

cf cf, all coll. Great Lakes Institute, 22.i.l964-6.i.l966

(GLI). Lake St. Clair: Sta. LS-13, oocfcf, coll. J.

Hiltunen, 5.V.1963. Lake Superior: Munising, Michigan, lcf, coll. E. L. Bousfield, 26.vi.1957; Batchawana Bay, Ontario, lcf, 29.viii.1959, lcf, 7.ix.l959,

2cf cf, 9.ix.l959, lcf, 25.ix.1959, 2cf cf, l.x.1959, all

coll. M.L.H. Thomas (NMC).

ONTARIO: Toronto, oo cf cf, coll. A. G. Huntsman, 18.X.1912 (ROM); Hamilton, 3cfcf, coll.

Messrs. Spragg and Dymond, 8.iv.l933 (ROM); Lake

Simcoe, lcf, coll. D. S. Rawson, no date (ROM);

Humber River,* York County, 4cf cf, coll. Ont. Dept.

P. & D., 12.vi.1946 (NMC); Moira River, Hastings

County, 2cf cf, coll. Ont. Dept P. & D., 8.viii.l947

(NMC); Moiia River, Hastings County, lcf, coll.

Ont Dept. P. & D., 27.viu.1947 (NMC); Port Dover,

2cf cf, coll. Ont. Dept. P. & D., June 1955 (NMC) ;

Port Rowan, lcf, coll. Ont. P. & D., 12.viii.1955

(NMC); Ottawa River, 6cf cf, coll. E. L. Bousfield,

4.v. 1957 (NMC); Moira River, Hastings County, 16

cf cf, coll. E. L. Bousfield, 28.V.1957 (NMC); Walpole Island, 12cf cf, coll. G. B. Wiggins, 6.V.1959

(ROM); Long Point, pond, 2cf cf, coll. D. Barr, 26.

v.1963 (ROM); Chaffey's Locks, Leeds County, 3

cfcf, coll. D. Barr, 21.vi.1964 (ROM); Rondeau

Province Park, lcf, coll. I. M. Smith, 3.vi.l965

(ROM); Dundas, oo cf cf, coll. N. Kaushik, November 1966; Port Credit, oo cf cf, coll. R. O. Brinkhurst,

29.iii.1967.

QUEBEC: Lievre River, oo cf cf, coll. F. Ide, 8.ix.

1928; Gatineau River, 3cfcf, coll. E. L. Bousfield,

November 1950 (NMC); Manikuagan, 4cf cf, coll.

E. L. Bousfield, 29.viu.1953 (NMC); Fairy Lake, Hull,

3cf cf, coll. E. L. Bousfield, 24.V.1957 (NMC).

DISTRICT OF COLUMBIA: Chain Bridge, 7

cfcf, coll. A. C. Weed, 13.xii.1908 (USNM).

INDIANA: Ohio River, Evansville, lcf, coll. U.S.

Dept. Interior, 16.vi.1965.

MARYLAND: Marshall Hall, 3cf cf, coll. A. Pizzini, 26.V.1934 (USNM).

MASSACHUSETTS: Amhurst, 3cf cf, coll. H. B.

N. Hynes, 23.ix.1960; Bull Hill, Montague, lcf, coll.

H. B. N. Hynes, September 1960.

MICHIGAN: Sugar Island, Chippewa County, 16

cf cf, coll. J. K. Hiltunen, 8.iii.l967.

VERMONT: Lake Champlain,* lcf, coll. E.L.

Bousfield, 19.vi.1956 (NMC).

WASHINGTON: Echo Lake,* King County,

5 cfcf, coll. E.L. Bousfield, 20.vi.1955 (NMC).

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

localities detailed above, together with the type locality, are plotted in Figure 30. In general and except

for its absence from Colorado, A. racovitzai racovitzai

has a somewhat similar distribution to A. communis,

its main area of distribution being in southeastern

Canada and northeastern United States. It seems,

however, not to extend so far east as does A. communis, although this may be the result of an inadequate number of collections. The occurrence of the

subspecies together with A. communis (the two taxa

occurred in the same collection) in Echo Lake, King

County, Washington, is of considerable interest, and

Bousfield's remarks on this locality, as well as the comment concerning the possibility of missorting of labels

and Hatch's (1947) key, are again pertinent.

The large amount of material examined from the

Great Lakes, especially Lakes Erie and Ontario, suggests that A. racovitzai racovitzai is the dominant, if

not the exclusive, species of Asellus in the Great Lakes.

The only other species encountered in these collections

was A. forbesi, and this, as indicated by a single specimen, occurs in Lake Huron. Within the Great Lakes,

A. racovitzai racovitzai obviously has a wide vertical

distribution, for it occurred in collections (GLI) from
46

A. racovitzai

racovitzai

A. attenuatus

A. racovitzai

australis

FIGURE 30.—Geographical distribution.

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

20 to 42 meters deep. Apart from large lakes, the data

on labels in collections examined show that the taxon

may also occur in creeks, rivers, ponds, small lakes, and

swamps. Like A. communis, it appears to be wide

ranging with regard to choice of macrohabitat.

FURTHER DESCRIPTION (o*)-—Body: The smallest

male with well-developed secondary sexual characteristics had a body length of 4.0 mm; the largest male

examined was 15.0 mm.

First antenna: Flagellum 7- to 15-merous, the number of segments depending to some extent upon the

size of the specimen; flagellum tip reaching to proximal third or to distal margin of the last segment of the

peduncle of the second antenna; penultimate 2 or 3

segments bear aesthetascs.

Second antenna: Length 0.44 to 0.8 times that of

body, the fraction showing a rough inverse correlation

with absolute body length (as indicated by plotting

the appropriate values for the largest male in each of

twenty-seven collections). Flagellum 26- to 92-merous,

the number of segments showing a rough direct correlation with body length.

Mouthparts: See Table 1.

First peraeopod: 2 or 3 (usually 2) very strong,

teethlike spines at proximal end of palm. Some variation occurs in the shape of the palm and its triangular

process (Figure 31). The typical shape is as illustrated

for the holotype.

FIGURE 31.—Asellus racovitzai racovitzai, extent of variation

in palm shape of male first peraeopod: A, Lake Opinicon,

Ontario; B, Amhurst, Massachusetts; c, Lake Superior; D,

Hull, Quebec; E, Echo Lake, Washington; F, Hamilton,

Ontario; o, Washington, O.C.; H, Sugar Island, Michigan.

H
NUMBER 49 47

FIGURE 32.—Asellus racovitzai racovitzai, extent of variation in morphology of endopodite tip of

male second pleopod: A, Lake Erie; B, Batchawana Bay, Lake Superior; c, j , Toronto, Ontario;

D, H, Ottawa, Ontario; E, Port Credit, Ontario; F, Sugar Island, Michigan; o, Rondeau Provincial

Park, Ontario; i, Echo Lake, Washington.

First pleopod: Total length of appendage 1.0 to 1.3

times as long as second pleopod. Inner margin of sympod with 2 to 5 (usually 2 or 3) coupling hooks. Maximum width of distal segment 0.41 to 0.56 times

maximum length; outer margin slightly concave to

straight.

Second pleopod: 0 to 4 (usually 2) simple spines

near inner distal angle of sympod. Proximal segment

of exopod with 2 to 6 spines on outer margin, and distal

segment with 13 to 24 marginal spines. Maximum

length of distal segment of exopod 0.96 to 1.91 times

maximum width. Endopod 1.1 to 1.9 times as long as

distal segment of exopod. No gross morphological variations occur in the morphology of the tip of the

endopodite, but minor variations occur both within

a single collection of specimens and between collections from different localities. The range of variation

is illustrated in Figure 32. The cannula may vary from

a wide triangular structure (the usual condition, as

displayed by Figures 29D,E for the holotype), to a

rather narrow tubular one. The mesial process displays

its greatest variation in the nature of its tip, which may

be acutely pointed or appear to be quite rounded. A

somewhat similar sort of variation is displayed by the

caudal process which, nevertheless, is always prominent and never reduced. The small spines on the outer

lateral edge of the caudal process may or may not be

visible according to the position of mounting of the

appendage. Figure 32 includes a drawing of the endopodite tip of a specimen collected from Echo Lake,

Washington.

Uropod: See Table 2.

Asellus racovitzai austratis, new subspecies

FIGURES 33-36

ETYMOLOGY.—From the Latin australis, southern.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult cf, USNM 122687. Allotype: adult nonovigerous?, USNM 122688. Paratypes: 17 dtf, 5 nonovigerous and 3 ovigerous ? $, USNM 122689. Type

locality: small spring run, Leon County, Florida (no

further data available). The collection was made 10

April 1963 by Dr. W. M. Beck.

DESCRIPTION OF HOLOTYPE.—Body: Length,

9.0 mm.

Head: Eyes large and distinct

First antenna: Flagellum 8-merous and tip reaching

to distal margin of last segment of peduncle of second

antenna. First and second segments of peduncle subequal in length; third, three-quarters length of second
48 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

or first. First peduncle segment twice as long as wide;

second and third respectively 3.5 and about 4 times as

long as wide.

Second antenna: Length (6.0 mm) two-thirds body

length. Flagellum 54-merous.

First peraeopod (Figure 33A) : Dactylus slightly

longer than palm of propodus. Propodus 1.41 times

as long as wide, subtriangular; palm with a large triangular projection near midpoint about twice as long as

basal width, a much smaller projection between larger

projection and point of attachment of dactylus, 1 large

and 2 smaller teethlike spines on a slightly raised proximal projection, and a submarginal row of spines on

inner and outer surfaces.

First pleopod (Figure 33B) : Total length of appendage 1.08 times that of second pleopod. Sympod

subrectangular, 1.4 times as long as wide; inner margin

with 4 hooklike protuberances for coupling. Distal segment also subrectangular, but distal corners rounded;

inner and outer lateral margins more or less parallel;

twice as long as wide and 1.65 times as long as sympod;

distal margin and distal half of outer margin with

numerous short to moderately long simple spines.

Second pleopod (Figures 33C-E) : Sympod subsquare, maximum length only slightly greater (1.12)

than maximum width; 2 small simple spines occur

near inner distal angle. Proximal segment of exopod

with 3 short plumose spines on outer margin. Distal

segment of exopod ovate, maximum length 1.66 times

maximum width, with 20 short to very long plumose

spines on margin. Endopod about three-quarters total

length of exopod, and slightly shorter (0.95) than

length of distal segment of exopod; endopod narrow,

about (2.4) two and a half times maximum width

(exclusive of apophyses); inner and outer apophyses

occur basally. Cannula wide, not markedly triangular

in shape, outer edge thickened and not membranous;

slightly shorter than caudal process. Caudal process

large, ending in acute point terminally, and bearing

groups of fine setae on dorsal surface; lateral margin

with some small spines. Mesial process well developed,

sclerotized, acutely pointed, and almost as long as

cannula.

Uropod (Figure 33F) : 1.23 times as long as telson.

Peduncle about 3.5 times as long as greatest width

with many marginal spines. Exopod about two-thirds as

long as peduncle; endopod slightly shorter (0.96) than

peduncle.

PARTIAL DESCRIPTION OF ALLOTYPE ( $ ).—First

peraeopod: Shape and setation similar to that described for a female paralectotype of A. attenuates.

Palmar margin of dactylus with 9 teethlike spines.

"First" pleopod (Figure 33G) : Shape almost subovate; distal margin and distal half of outer margin

with 12 finely plumose spines; 3 short simple spines

are present submarginally along the proximal half of

the inner margin.

MATERIAL EXAMINED.—FLORIDA: Perry Creek,

Taylor County, oo o* <f, coll. W. M. Beck, 21.vii.1953;

Lafayette County, 210*0", coll. W. M. Beck, 12.xi.

1953; Waddell's Mill Creek, Jackson County, 20*0*,

coll. W. M. Beck, 7.x. 1954; Withlacoochee River,

Madison County, 70*0", coll. W. M. Beck, 2O.vii.

1955; Lake Econlockhatchee River, Seminole County,

Id1, coll. W. M. Beck, 27.iii.1956; Lake Econlockhatchee River, Iron Bridge, Seminole County,

20*0", coll. W. M. Beck, 26.vi.1956; Waddell's

Mill Creek, Jackson County, 2o* cT, coll. W. M. Beck,

28.xi.1960; Torreya St. Park,* Liberty County, Id1,

coll. W. M. Beck, 10.xii.1960; Aucilla River, Taylor

County, 140*0", coll. W. M. Beck, 9.iii.l961; Depot

Creek, Gulf County, 1 o", coll. W. M. Beck, 19.ix.1961;

Econlockhatchee River, Seminole County, 260*0*,

coll. W. M. Beck, 5.iii.l962; Lake Econlockhatchee

River, Orange County, 1 o*, coll. W. M. Beck, 6.iii.

1962; Waddell's Mill Creek,* Jackson County, 3d1 o",

coll. W. M. Beck, 19.iii.1963.

GEORGIA: Darien,* lo*, coll. E. L. Bousfield,

2.iii.l963.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—This

subspecies appears to be confined to the southeast

United States (Figure 30). Within this region it has

been collected from creeks and rivers.

FURTHER DESCRIPTION (o") •—Body: The largest o*

examined was 11.0 mm long, and the smallest, 3.0 mm.

First antenna: Flagellum 10- to 16-merous; last 3

penultimate segments bear aesthetascs.

Second antenna: Length 0.67 to 1.0 (usually 0.8 to

1.0) times that of body. Flagellum 46- to 78-merous.

Mouthparts: See Table 1.

First peraeopod: 2 to 4 but usually 3 teethlike spines

at proximal end of palm. The range of variation in

palm shape is indicated in Figure 34.

First pleopod: Total length of appendage 1.0 to 1.2

times as long as second pleopod. Inner margin of sympod with 2 to 5 coupling hooks. Maximum width of

distal segment 0.35 to 0.65 times maximum length; the

shape of the distal segment is somewhat variable

(Figure 35), but the distal margin is always rounded.
NUMBER 49 49

FIGURE 33.—Asellus racovitzai australis, A-F, holotype; o, allotype: A, dactylus and propodus

of first peraeopod; B, first pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces of tip of endopodite of second pleopod; F, uropod; o, "first" pleopod.

S78-615 O - 70 - 5
50 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 34.—Asellus racovitzai australis, extent of variation

in palm shape of male first peraeopod: A, Madison County,

Florida; B, E, Jackson County, Florida; c, Seminole County,

Florida; D, Taylor County, Florida.

Second pleopod: 1 to 4 simple spines near inner distal angle of sympod. Proximal segment of exopod with

2 to 5 spines on outer margin, and distal segment with

14 to 23 marginal spines. Maximum length of

distal segment of exopod 1.48 to 2.47 times maximum width. Endopod 0.72 to 1.2 (usually 0.9 to

1.0) times as long as distal segment of exopod. The extent of variation in the morphology of the tip of the

endopodite is indicated in Figure 36. Although there

is less variation than displayed by A. racovitzai racoA R C D

FIGURE 35.—Asellus racovitzai australis, extent of variation in

shape of first pleopod of male: A, Leon County, Florida; B,

F, o, H, Taylor County, Florida; c, Lafayette County, Florida;

D, E, Seminole County, Florida.

FIGURE 36.—Asellus racovitzai australis, extent of variation in

morphology of endopodite tip of male second pleopod: A,

Taylor County, Florida; n, Lafayette County, Florida; c, F,

Seminole County, Florida; D, Darien, Georgia; E, Jackson

County, Florida.

vitzai (cf. Figure 32), nevertheless, the three main

components—the caudal process, the cannula, and

the mesial process—do display some variation. The

usual pattern displayed by these structures is as indicated for the holotype (Figure 33E) .

Uropod: See Table 2.

SEPARATION OF A. racovitzai australis FROM THE

NOMINATE SUBSPECIES ( o* cf only).—Asellus racovitzai australis is principally distinguished from A. racovitzai racovitzai in that: (1) the length of the second

antennae relative to body length is greater in A. racovitzai australis; (2) the shape of the distal segment of

the first pleopod is more rounded in A. racovitzai australis; (3) the distal segment of the exopod of the second pleopod is longer relative to the length of the

endopod in A. racovitzai australis, and in this subspecies it is also longer relative to maximum width; (4)

the endopod of the second pleopod is shorter relative

to maximum width in A. racovitzai australis; and (5)

the cannula at the tip of the endopod of the second

male pleopod is wider in A. racovitzai australis and its

outer lateral margin is thickened. The most important of these differences are quantified in Table 4, which

also indicates the level of significance of each of the

subspecific differences.

Asellus forbesi, new species

FIGURES 37, 38, 40-42

ETYMOLOGY.—Named for S. A. Forbes.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult d, USNM 122052. Allotype: adult nonoviger-
NUMBER 49 51

TABLE 4.—Principal differences between Asellus racovitzai racovitzai and Asellus racovitzai australis

[males only]

length of second antennae

body length

length of endopod ( p i copo d ^

length of distal segment of exopod

 vi#

 *" *~ "'

.~\ (distal segment of exopod, pleopod 2)

lcPf!h

 (endopod, pleopod 2)

width

Range

M«

±S.D.

Range

M-

±S.D.

Range

M«

±S.D.

Range

M«

±S.D.

A. racovitzai racovitzai

0.44-0.80

0.60

0.08

1. 05-1. 89

1.34

0.18

0. 96-2. 00

1.45

0.20

2. 34-3. 20

2.78

0.24

A. racovitzai australis

0. 67-1.00

0.80

0.09

0. 72-1. 20

0.96

0.11

1. 48-2.47

1.78

0.25

2. 15-2.80

2.49

0.17

<• Difference between means highly significant in all comparisons (by "t" test, P=<0.001).

ous ? , USNM 122053. Paratypes: 5 c? <?, 5 nonovigerous and 9 ovigerous $ $ , USNM 122054. Type locality: flood pool of Rappahannock River, Culpeper

County, Virginia. The type collection was made 28

March 1967 by Dr. A. Weaver.

DESCRIPTION OF HOLOTYPE.—Body: Length, 12.5

mm.

Head: Eyes large and distinct.

First antenna: Flagellum 14-merous and tip reaching to point about two-thirds along last segment of

peduncle of second antenna; penultimate 3 segments

bearing aesthetascs. Second segment of peduncle longest; first, three-quarters length of second; third, twothirds length of second. First peduncle segment about

1.5 times as long as wide; second and third respectively

4 and 3 times as long as wide.

Second antenna: Length (8.5 mm) about twothirds (0.68) body length. Flagellum 66-merous.

First peraeopod (Figure 37A) : Dactylus distinctly

longer than palm of propodus. Propodus 1.2 times as

long as wide, subovate; palm with a single large triangular projection near midpoint, a smaller blunt projection between larger projection and point of attachment of dactylus, a single toothlike spine on a low

proximal projection with 3 stout spines proximal to

this, and a submarginal row of spines on inner and

outer surfaces.

First pleopod (Figure 37B) : Total length subequal

(1.06) to that of second pleopod. Sympod subrectangular, about 1.33 times as long as wide; inner margin

with one hooklike protuberance for coupling. Distal

segment subovate, widest about one-third towards

distal margin; maximum width just over half (0.59)

maximum length; several simple short spines occur on

the distal margin.

Second pleopod (Figures 37C-E) : Sympod subquadrate, maximum length only slightly greater (1.17)

than maximum width; medial and lateral margins very

slightly convex. Proximal segment of exopod irregularly

subtriangular, with 3 short and simple spines on outer

margin. Distal segment of exopod ovate, almost twice

(1.87) as long as wide, with 13 long plumose spines

on margin of distal half of segment, and a row of very

fine short spines on inner proximal margin. Endopod

two-thirds total length of exopod, and about threequarters (0.77) length of distal segment of exopod;

endopod slightly less (1.86) than twice as long as maximum width (regarded in all specimens of A. forbesi

as the distance between the outer margin of the outer

basal apophysis and the inner proximal angle of endopod). Outer basal apophysis not well developed,

rounded in outline; inner basal apophysis scarcely present. Cannula short and wide. Ventral groove prominent. Mesial process sclerotized, large, wide, hooklike,

and as long as cannula. Lateral process not prominent.

Caudal process wide, margin broadly rounded and

sclerotized, without associated hooks or spines, and

not protruding far beyond cannula and mesial process.

Uropod (Figures 37F, G) : 1.33 times as long as telson. Peduncle about twice as long as maximum width.

Exopod two-thirds length of peduncle, endopod as

long as peduncle; both rami have several moderately
52

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 37.—AseUus forbed, holotype: A, dactylus and propodus of first peraeopod; B, first pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces of tip of endopodite of

second pleopod; F, uropod; o, uropod and telson.
NUMBER 49 53

TABLE 5.—Principal differences between Asellus forbesi and Asellus obtusus

[males only]

A. forbesi A. obtusus

Maximum body length (mm)

length of second antennae

body length

No. of marginal spines on proximal segment of exopod of second

pleopod

.~\~ (endopod, pleopod 2)

width

uropod length

telson length

Range

M«

+ S.D.

Range

M«

+ S.D.

Range

M«

+ S.D.

18.5

0. 5-1.0

0.75

0. 12

0-4

1. 65-2. 64

2.05

0.22

0. 67-1.5

1.16

0.20

12.5

0. 8-1. 5

1.03

0. 19

1. 39-1. 84

1.63

0. 15

1. 0-2.0

1.48

0.32

Difference between means highly significant in all comparisons (by "t" test, P=<0.001).

long and fine spines distally, and numerous stronger

ones laterally.

PARTIAL DESCRIPTION OF ALLOTYPE ( ? ).—First

peraeopod (FIGURES 38A, B) : Relatively slender, but

dactylus and propodus arranged in a subchelate manner. Dactylus distinctly longer than palm of propodus

and with 8 teethlike spines on inner margin and a long

terminal claw. Propodus subtriangular, about 1.5 times

as long as maximum width; palm with a low triangular

projection near midpoint, and at proximal end 2 long

teethlike spines. Otherwise as described for a female

paralectotype of A. attenuates.

"First" pleopod (Figure 38c): Almost subrectangular in shape. Distal margin with 14 long finely

plumose spines.

MATERIAL EXAMINED.—GREAT LAKES: Lake

Huron: Sta. 13, 15 meters, lcf, coll. Great Lakes Institute, 6.xi. 1963 (GLI).

ONTARIO: Go Home Bay, lo*, Coll. W. A.

Clemens, August 1912 (ROM); New Durham, Brant

County, 4o"cf, coll. R. F. Cain, 24.V.1929 (ROM);

Lake Nipissing, lo*, coll. J. Oughton, 8.vii.l929

(ROM); L. Nipissing, lo*, coll. J. Oughton,

8.viii.l930 (ROM); Laird, oo c* d\ coll. unmarked,

June 1931 (ROM); Beattie Point, Ottawa R., 5o* <?,

coll. Macoun Field Club, 28.iv.1955 (NMC); Spitler

Ck., Holbrook, 30*0*, coll. Ont. P. & D., l.vi.1955

NMC); Tillsonburg, 180*0", coll. E. L. Bousfield,

30.viii.1956 (NMC); Metcalfe, 30*0*, coll. W. Sinclair, 4.V.1957 (NMC); Spitler Cr., Norwich, 90*0*,

coll. E. L. Bousfield, 29.V.1957 (NMC); Long Point,

50*0*, coU. D. Barr, 26.V.1963 (ROM); Rondeau

Province Pk., Kent Co., 4<?d\ coll. I. M. Smith,

2.vi.l965 (ROM); Chalk River, 00 <? o*, coll. H. B. N.

Hynes, 27.V.1966; Perch Creek, 80* o", coll. J. Bishop,

2.V.1967; Pond near Laurel Creek Reservoir, 00 c* o",

coll. C. Patterson, 16.V.1967.

DISTRICT OF COLUMBIA: Carberry Meadows,

00 o* 0*, coll. W. P. Hay, 10.xu.1892 (USNM); Piney

Branch, 3o*o", coll. W.H. Ball, 7.iv.l930 (USNM);

Piney Branch, 000*0", coll. W. H. Ball, l.v.1930

(USNM); Georgetown, 000*0*, coll. L. Hubricht,

date unmarked (USNM).

INDIANA: Hammond, 4o* 0*, coll. V. E. Shelford,

25.iv.1908 (USNM); La Porte, La Porte County,

000*0*, coll. L. Hubricht, 2.V.1941 (USNM).

IOWA: Riverside, Washington County, 00 o* b",

coll. L. Hubricht, 24.iv.1942 (USNM).

KENTUCKY: Bullitt County, 20*0*, coll. G. A.

Cole, 7.iii.l954; Caperton Swamp, 4o* o*, coll. G. A.

Cole, 26.iii.1954; Jefferson County, lo*, coll. G. A.

Cole, 2.V.1954; Louisville, 9 o* O*, coll. G. A. Cole,

26.xii.1954; Jefferson County, 7o" 0*, coll. G. A. Cole,

24.iii.1956 (NMC).

MARYLAND: Great Falls, 70*0*, coll. W. D.

Appel, 9.xi.l912 (USNM); Linden, 00 c* d\ coll. J. E.

Benedict, 28.ii.1926 (USNM); Hyattsville, 000*0",

coll. R. Greenfield, 18.ii.1928 (USNM); Hyattsville,

000*0*, coll. R. Greenfield, 10.ii.1929 (USNM);

Ridge, St. Mary's County, lld"d\ coll. W. H. Ball,

26.iv.1930 (USNM); Point No Point, 1 d\ coll. W. H.

Ball, 27.iv.1930 (USNM); near Plummer's Island,

00 o* d\ coll. W. D. Appel, 5.V.1935 (USNM); near
54

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 38.—Asellus forbesi, allotype: A, dactylus and propodus of first peraeopod; B, first

peraeopod; c, "first" pleopod.

Plummer's Island, 5cT d1, coll. W. D. Appel, 19.V.1935

(USNM).

MICHIGAN: Ann Arbor, 000*0", coll. L.

Hubricht, 30.iv.1941 (USNM); Fenton, 00 d cf, coll.

L. Hubricht, 19.iv.1942 (USNM); Kalamazoo

County, 2 c? c?, coll. R. L. Lippson, 12.iv.1967.

MISSOURI: Benbush, St. Louis County, 000*0",

coll. L. Hubricht, 8.iii.l936 (USNM); St. Charles,

Ho* o*, coll. L. Hubricht, 24.iv.1937 (USNM); River

Kirkwood, St. Louis County, 00 c? o*, coll. L. Hubricht,

10.iv.1938 (USNM); Grimsby, oocfc?, coU. L.

Hubricht, 25.iv.1938 (USNM).

NORTH CAROLINA: Chapel Hill, Durham

County, 60" o", coll. A. Weaver, 4.xii.l966; Chapel

Hill, Durham County, 2 c? c?, coll. A. Weaver, 27.iii.

1967.

OHIO: Shreve, Wayne County, 2cf cf, coll. W. A.

Shear, 23.iii.1967.

SOUTH CAROLINA: Anderson County, 40*0*,

coll. R. Prinz, 6.U966.

VIRGINIA: Driver, 00 0*0*, coll. L. Hubricht,

26.iii.1944 (USNM); South Gap, Bland County,

60*0", coll. A. Weaver, 21.iii.1967; Prince William

County, 14 cf cf, coll. A. Weaver, 28.iii.1967; Keysville, 4 c? cf, coll. A. Weaver, 28.iii.1967; Culpepper

County, 7 c? c?, coll. A. Weaver, 28.iii.1967.

WEST VIRGINIA: Mercer County, 3c?c?, coll.

W. A. Shear, 16.iv.1966; Mercer County, lc?, coll.

A. Weaver, l.xii.1966.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

localities listed above, together with the type locality,

are plotted in Figure 39. This indicates that A. forbesi

is found over a very large area of east-central United

States and in southern Ontario. It is clearly one of the

most widespread species occurring in North America.
NUMBER 49 55

FIGURE 39.—Geographical distribution.

The most frequently mentioned sort of locality from

which collections have been made are temporary

ponds, flood pools, and sloughs. However, the species

has also been collected from marshes, small creeks, and

at least on a few occasions from lakes also. One of the

lakes from which it has been collected is Lake Huron

where the species was obtained from a depth of 15 m.

Like several other geographically widespread species

of Asellus in North America, A. forbesi is clearly able

to live in a variety of macrohabitats.

FURTHER DESCRIPTION (d1)-—Body: The largest cf

examined was 18.5 mm long, and the smallest 6.0 mm.

First antenna: Flagellum 10- to 17-merous; flagellum tip reaching to midpoint or to distal end of the

last segment of the peduncle of the second antenna;

penultimate 3 segments bear aesthetascs.

Second antenna: Length 0.5 to 1.0 times that of

body, but usual length between one-half and twothirds body length. Flagellum 40- to 87-merous depending upon size.

Mouthparts: See Table 1.

First peraeopod: Spine on proximal projection of

palm usually toothlike but sometimes relatively slenFIOURE 40.—Asellus forbesi, extent of variation in palm shape

of male first peraeopod: A, Kalamazoo, Michigan; B, Chalk

River, Ontario; c, Long Point, Ontario; D, Washington, D.C.;

E, Hyattsville, Maryland; F, St. Charles County, Missouri;

G, Jefferson County, Kentucky; H, Nansemond County,

Virginia.

der; proximal projection itself prominent to scarcely

developed, and with 1 to 5 relatively long spines on

proximal margin. Some variation occurs in the shape

of the palm (cf. Figure 40).

First pleopod: Total length of appendage 0.84 to

1.19 times as long as second pleopod. Inner margin of

sympod with 0 to 4 (usually 2 or 3) coupling hooks.

Maximum width of distal segment 0.48 to 0.69 times

maximum length. Distal spines few to numerous, but

always simple and of moderate length. The typical

shape of the distal segment is subovate, but a little

variation occurs.

Second pleopod: Maximum length of sympod from

1.10 to 1.60 (usually 1.2 to 1.4) times maximum width.

Proximal segment of exopod with 0 to 4 short and simple spines on outer margin; distal segment with 10 to

20 marginal spines. The shape of the distal segment

of the exopod varies from almost subcircular to elongate oval, the maximum length ranging from 1.48 to

2.54 times the maximum width; the usual shape, however, is ovate, and the maximum length is usually

about twice the maximum width. Endopod shape is

also rather variable, particularly concerning the extent

of development of the basal apophyses; an indication

of the range of variation is given in Figure 41. Considerable variation in endopod shape may occur even

within a single population, but the typical shape is that

shown for the holotype (Figure 37G). The maximum

length of the endopod is from 1.65 to 2.64 (usually 1.9
56 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 41.—Asellus forbesi, extent of variation in endopodite

shape of male second pleopod: A, Beattie Point, Ontario; B,

Laird, Ontario; c, D, j , Nansemond County, Virginia; E, O, H,

para types; F, Jefferson County, Kentucky; i, St. Charles

County, Missouri.

to 2.3) times the maximum width; the length in proportion to the length of the distal segment of the

exopod ranges from 0.60 to 1.04. The morphology of

the tip of the endopodite, while constant in fundamental characters, is subject to some variation particularly in the nature of the cannula and the mesial

process and the relationship these have to each other.

Figure 42 has been compiled to illustrate the range of

this variation. As may be seen, the mesial process may

appear to be much shorter than the cannula in some

specimens, subequal in length in others, and even in

some slightly longer; its shape, moreover, is rather variable and its tip may be blunt and rounded or acute

and narrow.

Depending to at least some extent it seems upon

the state and nature of preservation of the specimen

involved and the position of mounting of the pleopod

for examination, the cannula may appear as a prominent semitubular structure or as a scarcely visible and

almost flattened structure; it is always membranous.

The caudal process is always rounded, sometimes irregularly so, sclerotized, and lacks associated protuberances. With regard to the morphology of the tip of the

endopodite, A. forbesi appears to be one of the more

variable of North American epigean species of Asellus,

and the same can also be applied with respect to the

overall shape of the endopod. A study of the available

material did not indicate that any of this variation

had an obvious geographical basis, although this is not

to say of course that the variability is not correlated

with the very wide geographical distribution of the

species (the wide geographical distribution may be

a consequence of the variability).

Uropoda: See Table 2.

REMARKS.—Several collections from the United

States and belonging to the USNM had been collected

FIGURE 42.—Asellus forbesi, extent of variation in morphology of endopodite tip of male second

pleopod: A, Brant County, Ontario; B, O, Beattie Point, Ontario; c, Jefferson County, Kentucky;

D, Washington, D.C.; E, Hammond, Indiana; F, Chalk River, Ontario; H, Genesee County,

Michigan.
NUMBER 49 57

by L. Hubricht, and most of these but not all had associated labels indicating that Hubricht regarded the

material as belonging to the species "A. militaris." Several Canadian collections belonging to the ROM likewise were so labeled, but for these identification had

been carried out by J. G. Mackin. As indicated previously, the name A. militaris is a synonym for A. intermedius and the resurrection of the name by Mackin

(1940) following its synonymy with A. communis by

Hay (1882), Richardson (1905), and Van Name

(1936) has no validity. It seems clear, nevertheless,

that Mackin and Hubricht, who worked in close collaboration, should be credited with an awareness of the

separate identity of the taxon here referred to as A.

forbesi. In the case of Hubricht the awareness was by

no means exact, for some collections that are undoubtedly referable to A. forbesi are labeled as "A.

intermedius."

AseUus obtusus, new species

FIGURES 43-45

ETYMOLOGY.—From the Latin obtusus, blunt.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult o", USNM 122060. Allotype: adult ovigerous $ ,

USNM 122061. Paratypes: 9<? d, 1 ovigerous $ ,

USNM 122062. Type locality: temporary pond,

Florenville, St. Tammany Parish, Louisiana. The type

collection was made 26 February 1966 by Dr. W. G.

Moore.

DESCRIPTION OF HOLOTYPE.—Body: Length, 9.5

mm.

Head: Eyes large and distinct.

First antenna: Flagellum 17-merous and tip reaching to point about one-third along last segment of

peduncle of second antenna; penultimate three segments with aesthetascs. Flagellum slightly longer than

peduncle. Second segment of peduncle longest; first,

three-quarters length of second; third, half length of

second. First peduncle segment about twice as long

as wide; second and third respectively about 4 and

3.5 times as long as wide.

Second antenna: Length (10.5 mm) slightly greater

(1.1) than body. Flagellum 85-merous. Fourth and

fifth segments of peduncle respectively 5 and 9 times

as long as wide.

First peraeopod (Figure 43A) : Propodus 1.4 times

as long as wide, of irregular triangular shape; palm

with a single large triangular projection near midpoint,

a second blunter projection half height of larger projection and lying between this and point of attachment

of dactylus, a low proximal projection bearing apically

a long stout spine and proximally two smaller spines,

and a submarginal row of spines on inner and outer

surfaces.

Second to seventh peraeopoda: Segments generally

a little more elongated and setose than as described

for A. communis, and dactyli bear slightly more teethlike marginal spines. The proportions of the segments

to each other in a given peraeopod are nevertheless

similar to those described for A. communis. Figure

43B, which illustrates the fifth peraepod, serves as an

example of these differences (cf. Figure 4A).

First pleopod (Figure 44A) : Total length subequal

(1.1) to that of second pleopod. Sympod subsquare,

maximum length only slightly greater (1.14) than

maximum width; inner margin with 3 hooklike protuberances for coupling. Distal segment subovate, widest near midpoint; maximum width just over half

(0.59) maximum length; several simple short spines

occur on distal margin.

Second pleopod (Figures 44B-D) : Sympod subrectangular, maximum length 1.3 times maximum width;

medial and lateral margins more or less straight.

Proximal segment of exopod subrectangular, lacking

marginal spines. Distal segment of exopod ovate, maximum length slightly greater (2.1) than twice maximum width, and with 1 short and 13 long plumose

spines on margin of distal half of segment Endopod

two-thirds total length of exopod, and three-quarters

length of distal segment of exopod; endopod 1.73

times as long as maximum width (regarded in all

specimens of A. obtusus as the distance between the

apex of the outer basal bulge and the inner proximal

angle of the endopod). Basal apophyses not developed;

inner proximal angle almost a right angle. Cannula

very short and wide; outer margin forming a distinct

recurved lip. Ventral groove short and wide. Mesial

process sclerotized, large, very wide, blunt, and as long

as cannula. Lateral process not prominent. Caudal

process wide, margin broadly rounded and sclerotized,

without associated hooks or spines, and not protruding

far beyond cannula and mesial process.

Uropod (Figure 43c): One and three-quarters as

long as telson. Peduncle slightly more than twice as

long as maximum width. Exopod as long as peduncle,

endopod slightly longer (1.13) than peduncle. Both

rami and peduncle bear laterally very many long fine

and simple spines.
58

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 43.—Asellus obtusus, holotype: A, distal segments of first peraeopod (palm and dactylus

shown in greater detail); B, fifth peraeopod; c, uropod and telson.

Telson (Figure 43c): Lateral and distal margins

with numerous short and very long fine and simple

spines.

PARTIAL DESCRIPTION OF ALLOTYPE ( $ ).—First

peraeopod (Figure 44E) : Relatively slender, but dactylus and propodus almost subchelate. Dactylus about

as long as palm of propodus and with 10 stout spines

on inner margin and a terminal claw. Otherwise

similar to the description given for this appendage

in a female paralectotype of A. attenuatus.

"First" pleopod: Subtrapezoidal in shape, but broader distally than proximally; generally of similar outline to the "first" pleopod as described for a female

paralectotype of A. attenuatus (Figure 22c), but

width radier broader in proportion to length. Distal

margin with 18 long finely plumose spines.

MATERIAL EXAMINED.—FLORIDA: Torreya St.

Park,* Liberty County, Id1, coll. W. Beck, 10.xii.1960;

roadside ditch, Jefferson County, oo d d, coll. W.

Beck, 17.ix.1961; Waddell's Mill,* Jackson County,

10 c? d, coll. W. Beck, 19.iii.1963; Escambia River,

Escambia County, Id", coll. W. Beck, 19.xi.1963.

GEORGIA: Darien,* Id, coll. E. L. Bousfield,

2.iii.l963 (NCM).

LOUISIANA: Baton Rouge, Id1, coll. T. E. Simpson, 19.L1965 (NMC); St. Tammany Parish, lie? d1

,

coll. W. G. Moore, 2.ii. 1966; Florenvilk, St. Tammany

Parish, lid1 d, coll. W. G. Moore, 26.ii.1966; Bridge

City, Jefferson Parish, 8dd, coll. W. G. Moore,

19.iii.1966; Crown Point, Jefferson Parish, lo", coll.

W. G. Moore, 4.iii.l967; Bossier Parish, 6<?d, coll.

W. G. Moore, 29.iv.1967; Natchitoches Parish, lOd d,
NUMBER 49 59

FIGURE 44.—Asellus obtusus, A-D, holotype; E, allotype: A, first pleopod; B, second pleopod;

c, D, respectively dorsal and ventral surfaces of tip of endopodite of second pleopod; E, terminal

segments of first peraeopod.

coll. W. G. Moore, 29.iv.1967; Red River Valley,

Rapides Parish, 2<? d, coll. W. G. Moore, 29.iv.1967;

near Grand Bayou, Red River Parish, 2cfc?> coll.

W.G. Moore, 29.iv. 1967.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—As may

be seen from the map (Figure 39) in which the above

localities are plotted, A. obtusus is known only from a

relatively small region in the southeastern corner of the

United States. Within this region it seems to inhabit

a variety of waters and has been recorded from

swamps, roadside ditches, temporary ponds, and in

one case each a river and a small stream.

FURTHER DESCRIPTION (c?)-—Body: The largest o"

examined was 12.5 mm long, and the smallest 6.0 mm.

First antenna: Flagellum 12- to 23-merous; flagellum tip reaching one-third along or to distal margin

of the last segment of the peduncle of the second

antenna.

Second antenna: Length 0.81 to 1.5 times that of

body, but usual length subequal to body length. Flagellum 50- to 85-merous, depending on size.

Mouthparts: See Table 1.

First peraeopod: 2 to 4 spines may occur on the

proximal margin of the low proximal projection of the

palm; shape of palm shows little variation from that

illustrated for the holotype.

First pleopod: Total length of appendage 0.85 to

1.19 times as long as second pleopod. Inner margin of

sympod with 2 to 5 coupling hooks. Maximum width

of distal segment 0.52 to 0.66 times maximum length.

Distal spines few to numerous, but always simple and
60 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

of moderate length. The typical shape of the distal

segment is subovate.

Second pleopod: Maximum length of sympod from

1.07 to 1.50 (usually 1.1 to 1.3) times maximum

width. Proximal segment of exopod without marginal

spines; distal segment with 11 to 16 plumose marginal

spines. The shape of the distal segment is always ovate,

the maximum length, however, ranging from 1.42 to

2.19 (usually 1.6 to 1.9) times the maximum width.

Endopod shape is relatively constant (cf. A. forbesi),

the maximum length ranging from only 1.39 to 1.84

(usually 1.4 to 1.7) times the maximum width; the

length in proportion to the length of the distal segment

of the exopod varies from 0.64 to 1.06.

Although constant in fundamental construction, the

morphology of the tip of the endopod seems to provide

a variety of appearances depending upon the state of

preservation of the specimen, the position of the

endopod when examined, real differences between individuals, and perhaps other factors also. Figure 45

illustrates in part the extent of this variation; it is

based mainly on paratype material. As shown, the

outer lip of the cannula is developed to different degrees, the ventral groove may be relatively narrow or

broad and open, and the caudal outline (including the

caudal process) while always rounded exhibits some

variation in shape. The mesial process shows the most

variation of all; it may be relatively narrow and long,

wide and short, rounded or pointed. Like A. forbesi,

A. obtusus appears to be one of the more variable of

North American epigean species with regard to the

conformation of the tip of the endopod.

Uropoda: See Table 2. Peduncle and rami always

with many long fine lateral spines.

DISCUSSION.—The morphology of the tip of the endopod of the second male pleopod in typical specimens

of A. obtusus is sufficiently unlike that of any other

Asellus species to suggest that the taxon warrants

specific status on this criterion alone. Because this

morphology is basically similar in general plan to that

shown by A. forbesi for the same structure, however, it

is occasionally possible to be uncertain of the specific

identity using the morphology of the endopod tip by

itself. The two species can, nevertheless, always be

separated on a number of other characters: (1) A.

obtusus is a smaller species than A. forbesi; (2) the

second antennae are longer relative to body length in

A. obtusus; (3) the proximal projection on the palm

of the first cf peraeopod of A. obtusus bears apically a

long stout spine and never a toothlike spine as is usual

in A. forbesi; (4) the proximal segment of the exopod

of the second cf pleopod never has marginal spines in

A. obtusus, whereas it frequently does in A. forbesi; (5)

the endopod of the second cf pleopod in A. obtusus is

more squat, wider relative to length, always without a

developed outer basal apophysis, and with the inner

proximal angle almost a right angle; (6) the telson

and uropoda are much more spinose in A. obtusus than

A. forbesi (cf. Figures 43c, 37F, G) ; and (7) the

uropoda of A. obtusus relative to telson length are generally longer than those of A. forbesi. Many of these

differences are quantified in Table 5. Considered together with the differences in the morphology of the

FIGURE 45.—Asellus obtusus, extent of variation in morphology of endopodite tip of male second

pleopod: A, Jefferson County, Florida; B-E, O, H, paratypes; F, Red River Valley Parish,

Louisiana.
NUMBER 49 61

endopod tip of the second o* pleopod, they provide

firm grounds for the specific separation of the two

taxa.

Asellus laticaudatus, new species

FIGURES 46-48

ETYMOLOGY.—From the Latin latus, broad, and

caudatus, having a tail.

TYPE MATERIAL AND TYPE LOCALITY.— Holotype:

adult o", USNM 122055. Allotype: adult nonovigerous $. USNM 122056. Paratypes: 8o*cf, 1 nonovigerous and 1 ovigerous $, USNM 122057. Type

locality: roadside ditch near Haynes Boulevard, New

Orleans, Orleans Parish, Louisiana. The type collection was made 29 April 1961 by Dr. W. G. Moore.

DESCRIPTION OF HOLOTYPE.—Body: Length, 8.0

mm.

Head: Eyes large and distinct.

First antenna: Flagellum 10-merous and tip reaching to point about two-thirds along last segment of

peduncle of second antenna; last 3 segments bear

aesthetascs. Second segment of peduncle longest; first,

three-quarters length of second; third, two-thirds

length of second. First peduncle segment about 1.5

times as long as wide.

Second antenna: Length (5.0 mm) about two-thirds

(0.63) body length. Flagellum broken near tip; flagellum at least 61-merous and at least twice length of

peduncle.

First peraeopod (Figure 46A) : Propodus 1.2 times

as long as wide, subtriangular; palm with a broad and

large triangular projection near midpoint, a smaller

blunt projection between larger projection and point

of attachment of dactylus, 3 teethlike spines at proximal end, and a submarginal row of spines on inner

and outer surfaces.

First pleopod (Figure 46B) : Total length 1.34 times

that of second pleopod. Sympod subrectangular,

about 1.5 times as long as broad; inner margin with

5 (left) or 6 (right) hooklike protuberances for coupling. Distal segment also subrectangular, but distal

margin somewhat rounded; maximum width half

maximum length; distal margin and distal half of outer

lateral margin with numerous short to moderately long

simple spines rather irregularly arranged; inner distal

angle with a single simple spine.

Second pleopod (Figures 46C-E) : Sympod subquadrate, maximum length only slightly greater (1.20)

than maximum width; medial and lateral margins

slightly convex. Proximal segment of exopod subtrapezoidal, with 5 short and simple spines on outer margin. Distal segment of exopod ovate, 1.45 times as long

as wide, with 19 short to long plumose spines arranged

marginally, and a row of fine short spines on inner margin. Endopod four-fifths total length of exopod, and

the same length as the distal segment of the exopod;

endopod slightly greater (2.62) than two and a half

times as long as maximum width (regarded in all

specimens of A. laticaudatus as the distance between

the inner and outer margins of the endopod immediately distal to the basal apophyses). Both inner and

outer basal apophyses prominent and well developed.

Gannula long and wide and protruding prominently

at distal end of endopod. Ventral groove short, narrow,

and not prominent. Mesial, lateral, and caudal processes not developed, but distal part of mesial side of

ventral groove sclerotized and forming a flaplike structure. At the distal end of the endopod on the dorsal

surface numerous groups of about 3-6 minute setae

occur in the form of small combs.

Uropod (Figure 46F) : Slightly longer (1.11) than

telson. Peduncle twice as long as maximum width.

Exopod about two-thirds (0.62) length of peduncle,

endopod as long as peduncle; both rami are flat, lanceolate, and broad, the exopod being 3 times as long as

the maximum width, and the endopod 2.23 times.

Rami and peduncle bear numerous short to moderately

long spines on their lateral margins.

Telson (Figure 46o): Subsquare; lateral and distal

margins with numerous short and moderately long fine

and simple spines.

PARTIAL DESCRIPTION OF ALLOTYPE ( $ ).—First peraeopod (Figures 47A, B) : Relatively stout in general

proportions, and dactylus and propodus arranged in a

subchelate manner. Dactylus about same length as

palm of propodus and with 5 teethlike spines on inner

margin and a long terminal claw. Propodus broadly

subovate, 1.7 times as long as wide; palm with a single

long toothlike spine near midpoint, a very small triangular projection between long spine and point of

attachment of dactylus, and several long simple submarginal spines. Otherwise as described for a female

paralectotype of A. attenuatus.

"First" pleopod (Figure 47c): Shape similar to that

described for the allotype of A. forbesi, but setation
62

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 46.—Asellus laticaudatus, holotype: A, dactylus and propodus of first peraeopod; B, first

pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces of tip of endopodite of

second pleopod; F, uropod; o, uropod and telson.
NUMBER 49 63

FIGURE 47.—Asellus laticaudatus, allotype: A, dactylus and palm of first peraeopod; B, first

peraeopod; c, "first" pleopod; D, uropod and telson.

slightly different; inner margin with 6 short simple

spines, outer distal margin with 12 long plumose spines

and 2 short simple ones.

Uropod (Figure 47D) : Distinctly shorter (0.71)

than telson. Peduncle twice as long as maximum width.

Exopod about three-quarters (0.71) length of peduncle, endopod slightly longer (1.14) than peduncle;

both rami narrow and not markedly lanceolate.

MATERIAL EXAMINED.—KENTUCKY: Beargrass

Greek, Louisville, 14 d d1, coll. G. A. Cole, 15.ix.1955;

Louisville, 1 d, coll. G. A. Cole, December 1956.

LOUISIANA: Haynes Boulevard, New Orleans,

10 d d, coll. W. G. Moore, 29.iv.1961.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

above records together with the type locality are

plotted in Figure 13. The great distance between the

two regions from where the species is presently known

suggests that the species has a wide distribution in

southeast United States. Unfortunately no collections

of Asellus from the intermediate states of Alabama,

Mississippi, or Tennessee were available for study during the present investigation. A study of such collections is needed for confirmation or otherwise of this

distribution.

FURTHER DESCRIPTION (cf).—Body: The largest cf

examined was 11.5 mm long, and the smallest 6.0 mm.

First antenna: Flagellum 10- to 12-merous; last 3

segments bear aesthetascs.

Second antenna: Length 0.6 to 1.0 times that of

body. Flagellum about 65-merous.

Mouthparts: See Table 1.

First peraeopod: 2 or 3 spines at proximal end of

palm.

First pleopod: Total length of appendage 1.16 to

1.34 times as long as second pleopod. Inner margin of

sympod with 4 to 6 coupling hooks. Maximum width

of distal segment 0.49 to 0.58 times maximum length.

Second pleopod: Maximum length of sympod from

1.03 to 1.26 times maximum width. Proximal segment

of exopod with 2 to 5 short and simple spines on outer

margin; distal segment with 13 to 23 plumose, marginal

spines. The shape of the distal segment of the exopod

is always ovate, the maximum length, however, ranging from 1.23 to 1.63 times the maximum width.

Endopod shape is relatively constant, the maximum

length ranging from only 2.47 to 2.93 times the maximum width; the length in proportion to the length

of the distal segment of the exopod varies from 0.84 to
64

FIGURE 48.—Asellus laticaudatus, extent of variation in

morphology of endopodite tip of male second pleopod: A,

Beargrass Creek, Kentucky; B, D, Haynes Boulevard, Louisiana; c, Louisville, Kentucky; E, F, para types.

1.14. The morphology of the tip of the endopod is relatively constant, only minor differences being apparent

between individuals (Figure 48).

Uropoda: See Table 2. Both rami are always flat,

lanceolate, and broad; the endopod is from 2.23 to 2.5

times as long as maximum width.

Asellus scrupulosus, new species

FIGURES 49, 50

ETYMOLOGY.—From the Latin scrupulosus, rough

or jagged.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult cf, USNM 122069. Allotype: adult nonovigerous ? , USNM 122070. Paratypes: 25d* d1

, 21 nonovigerous and 4 ovigerous $ ° , USNM 122071. Type

locality: Lick Creek Road, Summers, 5 miles NE of

Athens, West Virginia. The type collection was made

19 March 1966 by Dr. W. A. Shear.

DESCRIPTION OF HOLOTYPE.—Body: length, 8.5 mm.

Head: Eyes distinct.

First antenna: Flagellum 10-merous and tip reaching to point about two-thirds along last segment of

peduncle of second antenna; penultimate 3 segments

bearing aesthetascs. Second segment of peduncle longest; first, three-quarters length of second; third, about

two-thirds length of second. First peduncle segment

about 1.5 times as long as wide; second and third respectively 3.5 and 3 times as long as wide.

Second antenna: Length (6.0 mm) about threequarters (0.71) body length. Number of segments in

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

flagellum unknown (impossible to count accurately)

but flagellum about 2.5 times length of peduncle.

First peraeopod (Figure 49A) : Dactylus slightly

longer than palm of propodus, with numerous very

small denticles on inner margin. Propodus 1.24 times

as long as wide, subtriangular; palm drawn out centrally into a very large triangular projection, and with

a much smaller projection between large projection

and point of attachment of dactylus, 1 large and 2

smaller teethlike spines at proximal end, and with a

submarginal row of spines on inner and outer surfaces.

First pleopod (Figure 49B) : Total length 1.18 times

that of second pleopod. Sympod subrectangular, about

1.5 times as long as wide; inner margin with 4 hooklike

protuberances for coupling. Distal segment subovate,

but slightly curved outward so that the distal part of

the outer lateral margin is shallowly concave and the

inner lateral margin convex; maximum width occurring about one-third toward distal margin and half

maximum length; distal margin with 5 very long

plumose spines and 5 very short simple submarginal

spines; inner distal angle with a single simple spine.

Second pleopod (Figures 49C-E) : Sympod subrectangular, maximum length 1.54 times maximum

width; medial and lateral margins more or less

straight. Proximal segment of exopod cupulate, with 3

short and simple spines on outer margin and a distinctly sclerotized inner margin. Distal segment of exopod subcircular, maximum length only 1.3 times maximum width, with 8 very long plumose spines on outer

and outer-distal margins, 4 shorter plumose and 3

shorter simple spines on inner-distal margin, numerous

minute setae on inner and inner-distal margins, and

with both proximal angles distinctly sclerotized. Endopod slightly longer (1.05) than total length of exopod,

and 1.4 times as long as the distal segment of the exopod; endopod about (2.44) two and a half times as

long as maximum width (exclusive of apophyses).

Both inner and outer basal apophyses prominent and

well developed. Cannula small and narrow. Ventral

groove distinct, but short and narrow. Mesial process

prominent, wide, long, and 4-toothed marginally.

Lateral process also prominent, but narrower and

hooklike. Caudal process not developed.

Uropod (Figure 49F) : As long as telson. Peduncle

slightly longer (2.28) than twice maximum width.

Exopod three-quarters length of peduncle, endopod

slightly shorter (0.91) than peduncle.
NUMBER 49 65

FIGURE 49.—Asellus scrupulosus, A-F, holotype; o, allotype: A, dactylus and propodus of first

peraeopod; B, first pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces of tip

of endopodite of second pleopod; F, uropod; o, "first" pleopod.
66

PARTIAL DESCRIPTION OF ALLOTYPE (?).—First

peraeopod: Relatively slender, but dactylus and propodus almost subchelate, as in the allotype of A. obtusns (cf. Figure 44E). Dactylus slightly longer than

palm of propodus and with 5 teethlike spines on inner

margin and a long terminal claw. Otherwise similar to

the description given for this appendage in a female

paralectotype of A. attenuatus.

"First" pleopod (Figure 49o): Shape subtriangular,

but outer margin gently convex with 1 short and

simple and 10 long and plumose spines on distal half.

Inner margin with a row of minute spinules near distal end and 3 short simple spines on proximal half.

MATERIAL EXAMINED.—WEST VIRGINIA: Summers County, 3 c? cf, coll. A. Weaver, l.xii.1966; Gamp

Creek State Forest, Mercer County, 3o* d\ coll. W. A.

Shear, 22.iii.1967; Hacker Valley, Webster County,

20*0", coll. A. Weaver, 25.iii.1967.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

species is known only from West Virginia (Figure 27),

where it has been collected from vernal and woodland

pools.

FURTHER DESCRIPTION (d1).—Body: The largest c?

examined was 11.5 mm long.

First antenna: Flagellum 10- to 15-merous; last 3

penultimate segments bear aesthetascs.

Second antenna: Length 0.58 to 0.71 times that of

body. Flagellum 59- to 71-merous.

Mouthparts: See Table 1.

First peraeopod: 2 or 3 teethlike spines at proximal

end of palm. The shape of the palm seems to display

little variation.

First pleopod: Total length of appendage 1.17 to

1.34 times as long as second pleopod. Inner margin

of sympod with 3 to 4 coupling hooks. Maximum width

of distal segment 0.4 to 0.5 times length; distal margin

with 3 to 6 very long plumose spines.

Second pleopod: Maximum length of sympod from

1.2 to 1.5 times maximum width. Proximal segment of

exopod with 3 or 4 short and simple spines on outer

margin; distal segment with 12 to 15 long and shorter

marginal spines, and maximum length 1.2 to 1.55 times

maximum width. Endopod shape is relatively constant,

but the maximum length varies from 2.4 to 3.3 times

the maximum width; the length in proportion to the

length of the distal segment of the exopod varies from

1.2 to 1.4. The morphology of the tip of the endopod

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 50.—Asellus scrupulosus, extent of variation in

morphology of endopodite tip of male second pleopod: A, B,

Summers County, West Virginia; c, Webster County, West

Virginia; D/E, F/O, two paratypes. A-C, E, O, ventral views;

D, F, dorsal views.

is quite constant, only minor differences being apparent

between individuals (Figure 50).

Uropoda: See Table 2.

Asellus nodulus, new species

Figures 51, 52

ETYMOLOGY.—From the Latin nodulus, nobbly.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult o*, USNM 122058. Allotype: adultovigerous $ ,

USNM 122059. Type locality: boggy ground in Gray's

Cypress Swamp, below Prince Frederick, Calvert

County, Maryland. The type collection was made 17

April 1938 by C.R. Shoemaker, and was formerly

labeled USNM "147/533."

DESCRIPTION OF HOLOTYPE.—Body: Length, 7.0

mm.

Head: Eyes small but distinct.

First antenna: Flagellum 13-merous and tip reaching to about midpoint of last segment of peduncle of

second antenna; penultimate 3 segments bearing

aesthetascs. Second segment of peduncle longest; first,

three-quarters length of second; third, two-thirds

length of second. First peduncle segment twice as long

as wide; second and third respectively 2.5 and 3 times

as long as wide.

Second antenna: Length (6.0 mm) slightly less

(0.86) than that of body. Flagellum 67-merous and

about 2.5 times as long as peduncle. Fifth segment of

peduncle about 5 times as long as wide.

First peraeopod (Figures 51A,B) : Dactylus with 4

teethlike spines on inner margin and a very long terminal claw. Propodus 1.78 times as long as wide, ovate;
NUMBER 49 67

FIGURE 51.—Asellus nodulus, holotypc: A, dactylus and palm of first peraeopod; B, first peraeopod; c, first pleopod; D, second pleopod; E, F, respectively dorsal and ventral surfaces of tip of

endopodite of second pleopod; o, uropod; H, uropod and telson.

378-615 O - 70 - 6
68 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

palm without triangular projections, but with 4 strong

teethlike spines on proximal half, and several short to

long spines in a submarginal row on inner and outer

surfaces.

First pleopod (Figure 51c): Total length 1.34

times that of second pleopod. Sympod subrectangular,

about 1.33 times as long as wide; inner margin with

4 large and 1 small hooklike protuberances for coupling. Distal segment subovate, but curved outward so

that the outer lateral margin is shallowly concave and

the inner lateral margin convex; maximum width

about one-third toward distal margin, and half maximum length; distal margin with 4 very long plumose

spines; distal half of outer distal margin with several

short and simple spines, and some similar spines also

occur submarginally near distal margin; inner distal

angle with 2 simple spines.

Second pleopod (Figures 51D-F) : Sympod subsquare, maximum length 1.28 times maximum width;

medial and lateral margins more or less straight. Proximal segment of exopod irregularly triangular, with 5

short and simple spines on outer margin. Distal segment of exopod broadly subtriangular, maximum

length only 1.19 times maximum width, with 7 long

plumose spines on outer margin, 1 long plumose spine

at apex, 6 moderately long plumose spines on distal

half of inner margin, a fringe of very short setae on

inner margin some setae of which extend submarginally in the form of small combs of 3-5 minute setae,

and a distinctly sclerotized inner proximal angle. Endopod same length as total length of exopod, and 1.5

times as long as the distal segment of the exopod;

endopod about (2.64) two and a half times as

long as maximum width (exclusive of apophyses).

Both inner and outer basal apophyses prominent and

well developed, particularly the outer which is subtriangular in side view. Cannula short, relatively narrow, and completely enclosed between prominent and

heavily sclerotized ventral and dorsal processes. The

total morphology is unique and difficult to homologize

with other North American species of Asellus; apparently the tip of the endopod has been subject to some

torsion, so that the ventral groove has come to lie near

the outer lateral margin; the prominent, broadly

rounded ventral process perhaps represents an enlarged

and slightly twisted (as indicated by striata) mesial

process, whereas the prominent, triangular, dorsal

process perhaps represents the caudal process.

Uropod (Figure 51c) : Almost (0.93) as long as

telson. Peduncle slightly longer (3.3) than three times

maximum width. Exopod as long as peduncle, endopod

1.33 times as long as peduncle; both rami with almost

parallel sides, several long fine setae on rounded distal

tips, and only sparsely spinose laterally.

Telson (Figure 51 H) : Subcircular, but maximum

length 1.2 times maximum width.

PARTIAL DESCRIPTION OF ALLOTYPE ( $ ).—First peraeopod: Relatively slender, but dactylus and propodus

almost subchelate, as in the allotype of A. obtusus (cf.

Figure 44E) . Dactylus about as long as palm of propodus and with 5 teethlike spines on inner margin and a

long terminal claw. Otherwise similar to the description given for this appendage in a female paralectotype of A. attenuatus.

"First" pleopod: Shape similar to that described for

the allotype of A. scrupulosus (cf. Figure 49o), but

setation rather different; 1 long and simple and 13 long

plumose spines present on distal lateral margin, 4 short

and simple spines irregularly arranged near inner proximal corner, and 1 short and simple spine at outer

proximal angle.

MATERIAL EXAMINED.—MARYLAND: Ridge, St.

Mary's County, 2^0", coll. W. H. Ball, 26.iv.1930

(USNM) ; Mechanicsville, St. Mary's County, lcf,

coll. W. H. Ball, ll.v.1937 (USNM); Bristol, 1 cf, coll.

A. Pizzini, 31.X.1937 (USNM).

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

species is known only from Maryland (Figure 27),

where it has been collected from a variety of habitats:

boggy ground in a swamp, rainwater in roadside ditch,

a woodland stream, and the outlet of a spring. All

known localities lie on the small peninsula southeast

of Washington, D.C., bounded by the Potomac River

and Chesapeake Bay.

FURTHER DESCRIPTION (cf)-—Body: The longest

o* examined was 10.5 mm long.

First antenna: Flagellum 13- or 14-merous; last 3

penultimate segments bear aesthetascs.

Second antenna: Length 0.67 to 0.89 times that of

body. Flagellum 61- to 85-merous.

Mouthparts: See Table 1.

First peraeopod: Considerable variation was apparent in the setation and palmar shape of the propodus

in the material examined. Thus referring to Figure

51A (holotype) and Figure 52 (all other known male

material), it can be seen that the extent of develop-
NUMBER 49 69

FIGURE 52.—Asellus nodulus, extent of variation in palm

shape of male first peraeopod: A, C, Ridge, St. Mary's County,

Maryland; B, Mechanicsville, St. Mary's County, Maryland;

D, Bristol, Maryland.

ment of triangular processes on the palm is variable,

as also is the number of proximal teethlike spines.

First pleopod: Total length of appendage 1.27 to

1.36 times as long as second pleopod. Inner margin of

sympod with 5 to 6 coupling hooks. Maximum width

of distal segment 0.48 to 0.52 times length; distal

margin with 3 to 5 very long plumose spines.

Second pleopod: Maximum length of sympod from

1.2 to 1.3 times maximum width. Proximal segment

of exopod with 5 or 6 short and simple spines on outer

margin; distal segment with 4 to 9 shorter and 8 to

10 longer plumose marginal spines (total: 12 to 17),

and maximum length 1.2 to 1.3 times maximum width.

Endopod shape is relatively constant, but the maximum

length varies from 2.5 to 3.0 times the maximum

width; the length in proportion to the length of the

distal segment of the exopod varies from 1.3 to 1.5.

The morphology of the tip of the endopod is quite

constant.

Uropod: See Table 2.

Telson: Maximum length 1.0 to 1.2 times maximum

length.

Asellus occidental**, new species

FIGURES 53, 55, 56

ETYMOLOGY.—From the Latin occidentalis, western.

TYPE MATERIAL AND TYPE LOCALITY.—Holotype:

adult d\ USNM 122063. Allotype: adult nonovigerous ? , USNM 122064. Paratypes: 9tf cf, 6 nonovigerous and 1 ovigerous $ ? , USNM 122065. Type

locality: Klamath River, near Falls between Lake

Ewuana and Upper Klamath Lake, Oregon. The type

collection was made 16 November 1965 by Mr. W.C.

Johnson and forwarded for study by Dr. J. B. Anderson, Federal Water Pollution Control Administration,

United States Department of Interior.

DESCRIPTION OF HOLOTYPE.—Body: Length, 7.0

mm.

Head: Eyes distinct.

First antenna: Flagellum 11-merous and tip reaching to midpoint of last segment of peduncle of second

antenna; penultimate 3 segments bearing aesthetascs.

Second segment of peduncle longest; first, three-quarters length of second; third, about two-third length of

second. First peduncle segment about 1.5 times as

long as wide; second and third about 3.5 times as long

as wide.

Second antenna: Length (6.5 mm) almost (0.93)

equal to that of body. Flagellum 55-merous and about

3 times as long as peduncle.

First peraeopod (Figure 53 A) : Dactylus with about

7 teethlike spines on inner margin. Propodus 1.76

times as long as wide, subovate; palm without triangular processes, with 4 prominent teethlike spines on

proximal half, and with numerous simple spines

submarginally.

First pleopod (Figure 53B) : Total length 1.34 times

that of second pleopod. Sympod subrectangular,

about 1.5 times as long as wide; inner margin with

3 hooklike protuberances for coupling. Distal segment

subovate, but inner margin more or less straight; maximum width occurring about two-thirds toward distal

margin, distinctly greater than width of sympod, and

about two-thirds maximum length; distal and outerdistal margins with several long plumose spines and

numerous shorter and simple spines somewhat

irregularly arranged.

Second pleopod (Figures 53C-E) : Sympod subrectangular, maximum length 1.23 times maximum

width; medial and lateral margins gently convex;

several moderately long simple spines occur near the

inner distal angle. Proximal segment of exopod irregularly triangular, without marginal spines. Distal

segment of exopod broadly subtriangular, maximum

length 1.5 times maximum width, with 17 long to

moderately long plumose spines on outer margin and

distal half of inner margin, a fringe of marginal setae

on distal two-thirds of inner margin, and a distinctly

sclerotized inner proximal margin. Endopod slightly

shorter (0.92) than total length of exopod, and 1.28

times as long as distal segment of exopod; endopod

about (2.57) two and a half times as long as maximum width. Endopod bent at approximately right
70 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 53.—Asellus occidentalis, holotype: A, dactylus and propodus of first peraeopod; B, first

pleopod; c, second pleopod; D, E, respectively dorsal and ventral surfaces of tip of endopodite of

second pleopod; F, uropod; o, uropod and telson.
NUMBER 49 71

angles near basal apophyses; outer basal apophysis

rounded, not well developed; inner basal apophysis

distinct, well developed, flaplike. Cannula short, moderately narrow, and completely hidden in ventral view

behind lateral process. Ventral groove prominent,

short, and wide. Mesial and caudal processes scarcely

developed. Lateral process well developed, large, subtriangular, bent dorsally at tip, and without associated

setae or spines.

Uropod (Figure 53F) : Not quite (0.83) as long as

telson. Peduncle about 2.5 times as long as wide.

Exopod distinctly longer (1.27) than peduncle, and

endoped slightly longer (1.03) than exopod; both

rami with several long fine spines on distal tips and

several stout long spines laterally.

Telson (Figure 53o) : Subcircular, but maximum

width greater (1.17) than maximum length; uropodal

sinuses distinct.

PARTIAL DESCRIPTION OF ALLOTYPE (?).—First peraeopod: General shape and setation similar to that

described for a female paralectotype of A. attenuatus,

but propodus with 2 long and stout teethlike spines

near middle of palm. Palmar margin of dactylus with

7 teethlike spines.

"First" pleopod: Shape similar to that described for

a female paralectotype of A. intermedius (cf. Figure

18c). Distal margin and distal half of outer margin

with 10 finely plumose spines.

MATERIAL EXAMINED.—BRITISH COLUMBIA:

Nanaimo, Vancouver Island, 3 o" o*, coll. E. L. Bousfield, 24.vii.1955 (NMC); Clayoquot Island, 10 c" d1

,

coll. E. L. Bousfield, 6.viii.l955 (NMC); Double Bay,

Vancouver Island, 6 c? d\ coll. E. L. Bousfield, 5.viii.-

1959 (NMC).

OREGON: Philomath, Benton County, 2<?d,

coll. G. B. Wiggins, 24.iv.1964 (ROM); Klamath

River, lOcTcf, coll. U.S. Dept. Interior, l.xii.1965;

Klamath River, 1 cf, coll. U.S. Dept. Interior, no date

marked.

WASHINGTON: Fort Simcoe, near Yakima,

3cfcT, coll. Margaret Anderson, 26.vi.1967.

GEOGRAPHICAL DISTRIBUTION AND ECOLOGY.—The

species is recorded only from the far northwestern

part of the United States and the extreme southwestern corner of British Columbia (Figure 54). Within

this area of distribution it has been collected from

spring-brooks, streams, rivers, and on one occasion

from the marshy edge of a lake.

A. occidentalis

FIGURE 54.—Geographical distribution.

FURTHER DESCRIPTION (cf)-—Body: The longest

c? examined was 11.0 mm long.

First antenna: Flagellum 9- to 12-merous; last 2 or

3 penultimate segments bear aesthetascs.

Second antenna: Length 0.68 to 0.93 times that of

body. Flagellum 42- to 60-merous.

Mouthparts: See Table 1.

First peraeopod: Palm of propodus always without

triangular process, with 3 to 5 prominent teethlike

spines variously arranged (Figure 55), and with

numerous simple spines submarginally.

First pleopod: Total length of appendage 1.15 to

1.45 times as long as second pleopod. Inner margin

of sympod with 2 to 4 coupling hooks. Maximum

width of distal segment 0.56 to 0.73 times length;

distal margin with 7 to 13 long plumose spines.

Second pleopod: Maximum length of sympod from

1.08 to 1.27 times maximum width. Proximal segment

of exopod with 0 to 1 short and simple spine on

outer margin; distal segment with 8 to 18 marginal

spines (apart from fringe of setae on inner margin),

and maximum length 1.06 to 1.57 times maximum

width. Endopod shape more or less constant in character, length 2.06 to 2.72 times maximum width, and

1.15 to 2.24 times length of distal segment of exopod.
72

A little variation is displayed by the terminal arrangement of the endopod (Figure 56).

Uropod: See Table 2.

FIGURE 55.—Asellus occidentalis, extent of variation in shape

and spinulation of propodus of male first peraeopod: A, Victoria Island, British Columbia; B, Clayoquot Island, British

Columbia; c, Klamath River, Oregon; D, Fort Simcoe, Washington; E, Nanaimo, British Columbia.

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Uncertain Name

The name Asellus tomalensis was first proposed by

Harford in 1877 (pp. 54-55) for a single specimen of

Asellus obtained from "Tomales Bay and vicinity."

The description was very short, unaccompanied by

drawings, and was impossible to use for the certain

identification of the taxon involved. Richardson (1900,

p. 297) was aware of this, and consequently only tentatively referred to A. tomalensis some material that had

been collected from Lake Washington, Seattle (1904a,

b). This material was actually compared (by Dr. W. E.

Ritter) with the single specimen of A. tomalensis identified by Harford, but the comparison was clearly

superficial as indicated by Richardson's report of it

(1904a, pp. 224-225). Richardson did provide a description of her material, but this description likewise

is insufficient for diagnostic purposes, and gives, for

example, no details for any pleopod (cf. Van Name,

1936, p. 406). Harford's type was redescribed in 1904

by Holmes, but the redescription, though more complete, provided no further clarification of the species

identity; moreover, it indicated that the specimen was

a female: "first pair of pleopods very small and oblong;

second pair not fused in the middle, and forming an

operculum over the succeeding ones" (1904, p. 322).

This specimen, which had been deposited in the California Academy of Sciences, Registration No. 2609,

was subsequendy destroyed by fire and earthquake in

FIGURE 56.—Asellus occidentalis, extent of variation in morphology of endopodite tip of male

second pleopod: A, B, Victoria Island, British Columbia; 3, Clayoquot Island, British Columbia;

D, Benton County, Oregon; E-H, paratypes. A-E, ventral views; F-H, dorsal views.
NUMBER 49 73

1906 according to D. Chivers and G. E. Lindsay, respectively staff member and director of the California

Academy of Sciences, San Francisco (personal communication, 27 July 1967).

In view of the certain destruction of the type, the

absence of an adequate description, the failure of colleagues (Drs. N. H. Anderson and G. E. Clothier) to

collect Asellus from the Tomales Bay area of California, and the occurrence of at least three distinct

epigean taxa of Asellus {A. racovitzai racovitzai, A.

communis, and A. occidentalis) in the western part of

North America, Asellus tomalensis is here regarded as

a name not certainly applicable to any known taxon.

The application of the name by several authors (e.g.

Carl, 1937; Hatch, 1947) to material examined by

them is without firm foundation. It is possible that the

new species described in this paper as A. occidentalis

is conspecific with Harford's taxon but this cannot be

verified, and the situation seems best resolved by the

course of action here adopted.

Species Originally Referred to Asellus

In addition to the names mentioned in this paper,

reference should also be made to species originally

described as species of Asellus but subsequently transferred to the genus Lirceus. The original names are

Asellus lineatus Say, Asellus tenax Smith, Asellus hoppinae Faxon, Asellus hoppiae Packard, and Asellus

incisus Van Name.

Lirceus lineatus was described by Say in 1818. The

description although exceedingly brief and without

figures did indicate that there was on the head "a

sinus each side in the middle" (p. 438); it may be presumed that this refers to a lateral incision of the head

margin, a feature of frequent occurrence in the genus

Lirceus but never present in Asellus. Its occurrence

provides firm support for the inclusion of the species

in the genus Lirceus (Hubricht and Mackin, 1949).

The name Asellus tenax was put forward by Smith

(in Smith and Verrill, 1871). Smith noted (see also

Smith, 1874) that his taxon lacked mandibular palpi,

and after transference to the genus Asellopsis by Harger

(1874) and then Mancasellus (Harger, 1876), it was

synonymized by Hubricht and Mackin (1949) with L.

lineatus. The lack of a mandibular palp certainly

excludes it from the genus Asellus.

Lirceus hoppinae was described by Faxon (in Garman, 1889) and was treated as a species of Asellus until

fairly recently (e.g., Van Name, 1936; Mackin and

Hubricht, 1938). It was transferred to the genus

Lirceus and redescribed by Hubricht and Mackin in

1949, although these authors did not state what specimens they used as a basis for their description and do

not mention type material. Through the courtesy of

Miss A. B. Bliss, Museum of Comparative Zoology,

original type material (three slightly damaged adult

males in alcohol) was located in that Museum, and

from the labels inside the container and the state of the

material itself it seems not to have been examined by

Hubricht and Mackin. There is no record that these

authors examined this material (Miss A. B. Bliss, personal communication, 11 December 1967). The labels

read: "Mus. Comp. Zool. Cambridge Mass. No. 4203

Coll. Miss Ruth Hoppin Asellus hoppinae Fax. Typus

Day's Cave, Mo.," "25: J^4," "Dave's Cave in mud under stones," and "4203." Examination of this material

confirmed the correctness of the generic transference

effected by Hubricht and Mackin and also of critical

details in their specific redescription. Thus, the specimens have the typical body outline fades of Lirceus,

and have 3-jointed mandibular palps, third pleopoda

with the exopodite divided by a diagonal suture into a

large proximal portion and a smaller moon-shaped distal portion, and in appearance of the telson, uropoda

and gnathopoda agree with the drawing given by

Hubricht and Mackin (1938; plate 3 A-C) forL. hoppinae hoppinae. Packard's (1894) name, Asellus hoppiae, was synonymized by Van Name (1936) with

Asellus hoppinae and accordingly becomes a synonym

of L. hoppinae hoppinae.

A further synonym of L. hoppinae, according to

Hubricht and Mackin (1949), is Asellus incisus described by Van Name (1936). The generic transference, at least, is undoubtedly warranted for Van

Name's original description includes a clear diagram

of the head (fig. 202), showing incised lateral margins

and the frontal shape typical for the anterior head

margin of Lirceus.

Coexistence of Species

The vast majority of collections examined during the

present investigation were unispecific, at least as far as

males were concerned. A few, however, were not, emphasizing the need for care in determining material.

The number of collections containing two species, and

the species involved, are indicated below:
74 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

A. communis -\-A. racovitzai racovitzai 2 collections

A. intermedius-\-A. racovitzai racovitzai 1 collection

A. intermedius-\-A. brevicauda brevicauda 1 collection

A. obtusus -\-A. racovitzai australis 3 collections

Phylogenetic Relationships

It is clear that any attempt to determine phylogenetic

relationships within the North American epigean species of Asellus must be based almost entirely upon the

structure of the male genital pleopods, and particularly

upon the morphology of the endopod tip of the male

second pleopod; apart from the shape of the palm of

the male first peraeopod, other parts of the body while

providing some characters of diagnostic use may be

more or less discounted in this respect. Steeves (1966),

who dealt with the evolution of North American troglobic Asellus, clearly recognized this and indeed based

his conclusions upon only the endopodial tip of the

male second pleopod. On other grounds, however, certain general criticisms can be raised against Steeves'

method of evolutionary analysis. Thus, his evolutionary

scheme was the result principally of a series of hypothetical derivations of increasing complexity from ancestors that to him appeared to have the simplest

( = most primitive) structure of endopod tip. Further,

it took no account of sister groups and involved multiple derivation of species from a single taxon ("alabamensis"), a concept which is, as emphasized generally

by Brundin (1966), unrealistic. Steeves' method of

evolutionary analysis, like all such methods, is therefore

open to the same type of criticism that Brundin (1966)

has leveled, justifiably for the most part in the opinion

of the present author, at the numerous "phylogenies"

purporting to indicate phylogenetic relationships but

which take no cognizance of the sort of strict phylogenetic principles first enunciated clearly by Hennig

(1950).

Hennig's ideas, which emphasize the relative importance of plesiomorphic (primitive) and especially apomorphic (derived) characters, and the importance of

sister group delimitation, provide a much more precise

basis for determining phylogenetic relationships, and

in the following discussion dealing with the relationships of North American epigean species of Asellus an

attempt is made to apply them. Although there are

many difficulties in such an application, resulting

mainly from the paucity of useful characters, and,

in part consequence of this, from varying degrees of

uncertainty as to whether a given character is plesiomorphic or apomorphic, it is felt that it is only by the

application of Hennig's ideas that true relationships

within Asellus can be ascertained.

It should perhaps first be stated that it seems valid

to deal with the evolution of the North American epigean asellids as a single entity without involving intercontinental relationships {A. aquaticus is not considered in this section), for only two phylogenetic groups

seem to be involved. One group, the largest and containing all but one species, seems to be of monophyletic

origin in that with two exceptions all included taxa

possess the undoubtedly synapomorphic character of a

large triangular projection on the palm of the propodus of the male first peraeopod. The exceptions, A.

brevicauda bivittatus and A. nodulus, may reasonably

be regarded as having secondarily lost the triangular

process; there can be no doubt of the close relationship

of A. brevicauda bivittatus to A. brevicauda brevicauda

which has the triangular process, and the triangular

process is in fact sometimes present in A. nodulus. Secondary loss of the triangular process cannot reasonably

be advanced to explain its absence in the western

species, A. occidentalism and we must therefore regard

this taxon as constituting a second phylogenetic group

of uncertain affinities with the first. No synapomorphic

characters seem to be possessed by these two groups

which set them apart as a single unit from Palaearctic

species of Asellus. The great extension of the lateral

process and the absence of either well-developed caudal or mesial processes on the endopod of the male second pleopod of A. occidentalis is also a structural pattern not displayed by any other North American

epigean species of Asellus and gives further support for

regarding A. occidentalis as part of a separate phylogenetic group.

In dealing with the relationships of the major phylogenetic group, we may take as an arbitrary starting

point the decidedly apomorphic species A. montanus.

It is difficult to equate the morphology of the endopod

tip of the male second pleopod of this species with any

other species, but there can be no doubt that the torsion of the endopod is an apomorphic character. The

only other species which displays torsion of the endopod is A. nodulus, and it is this species, therefore,

which must be regarded as the sister species of A. montanus. Parallel evolution may have been involved in

producing the torsion effect, but as pointed out by

Brundin (1966) unless there is proof to the contrary

synapomorphies must in the first instance be regarded
NUMBER 49 75

as indicating phylogenetic relationship and not used to

anticipate parallelism.

Both A. montanus and A. nodulus possess a first

pleopod that is distinctly longer than the second, and

which has an elongate distal segment with long plumose spines on its distal margin. The only other eastern

species to possess a similar first pleopod are A. brevicauda, A. scrupulosus, A. kenki, and A. dentadactylus;

the remaining species have a first pleopod that is

shorter or more or less subequal in length to the second

and lacks plumose distal spines. It is not possible to be

certain as to which of these two structural patterns is

apomorphic and which plesiomorphic, but the distinction between them is so clear and must surely involve

so many genie differences that it seems reasonable to

regard the distinction as of considerable phylogenetic

significance. Accordingly, the four species A. brevicauda, A. scrupulosus, A. kenki, and A. dentadactylus,

are here regarded as comprising the sister group to

A. montanus and A. nodulus. For present purposes, we

may regard all six species as related principally by their

synapomorphic first pleopods.

Apart from A. montanus and A. nodulus, the structure of the endopod tip of the male second pleopod in

all other North American species of Asellus may be

conceived as a series of developments of three main

structures associated with the ventral groove and terminal cannula: the mesial, lateral, and caudal processes. It seems reasonable to presume that any of these

structures that is highly or peculiarly developed constitutes an apomorphic character, and, conversely, that

absence or slight development indicates plesiomorphy.

The lateral process is variously developed in A.

brevicauda, A. scrupulosus, and A. kenki, but not in

A. dentadactylus, in which species, however, the caudal

process is well developed and dentate. The first three

species, therefore, may be regarded as the sister group

to A. dentadactylus. In A. kenki the mesial process,

according to Bowman (1967), is a simple rounded

structure, but in A. brevicauda and A. scrupulosus it is

sclerotized and either rugose or dentate. The latter

condition is probably the apomorphic one, and it

unites these two species as the sister group to A. kenki.

The basic structure of the endopod tip of the male

second pleopod in A. scrupulosus and A. brevicauda is

very similar, but in the former species the mesial process is dentate and the lateral process heavily sclerotized,

suggesting that of these two species A. scrupulosus is

the more apomorphic. It may be noted, however, that

the very short uropoda of A. brevicauda are certainly

apomorphic.

Turning now to those species that have a first pleopod of an apparently plesiomorphic nature, that is,

short and lacking plumose setae, two distinct sister

groups are clearly involved: one in which the mesial

process is well developed, and one, presumably more

plesiomorphic, in which it is not. Of the former group,

A. racovitzai appears to be the most apomorphic

species, showing relative prolongation of the cannula

and mesial process, and with a well developed and

pointed caudal process having a series of setal combs

on its dorsal surface. The sister species to A. racovitzai

is unquestionably A. attenuatus. Both A. forbesi and

A. obtusus have caudal processes of a simple and apparently plesiomorphic nature, and in both the cannula is short and wide; they probably represent, therefore, the more plesiomorphic sister group to the A.

racovitzai I A. attenuatus group. The relatively greater

development of the mesial process of A. forbesi suggests that it is more apomorphic with regard to its

endopodial armature than A. obtusus.

Of the three species without a well developed mesial

process, namely, A. communis, A. intermedius, and

A. laticaudatus, the former two appear to be related

by their possession of a more or less well-developed

caudal process, and they form, consequently, the sister

group to the more plesiomorphic species A. laticaudatus which lacks a caudal process.

The tentative phylogenetic relationships suggested

above are expressed in diagrammatic form in Figure

57.

Acknowledgments

The major part of the work reported in this paper was

carried out in the Department of Biology, University

of Waterloo, Canada, and was supported by the award

to me of a Canadian Government Research Fellowship.

It was completed and prepared for publication at the

Limnologische Flu/Jstation, Schlitz, Western Germany,

where I was a guest of the Max-Planck-Instituts fur

Limnologie. In Canada, Prof. H. B. N. Hynes, Chairman, Department of Biology, provided stimulation,

encouragement, and facilities and he is gratefully

acknowledged for these; in Germany, Prof. J. lilies,

Director, Limnologische Flu/Jstation, likewise showed

great interest in the work and is also thanked.

Without the cooperation of a very large number of

North American colleagues the extent of this work
76 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 57.—Tentative phylogenetic relationships of North American epigean species of Asellus,

arranged according to the ideas of Hennig (1950). Black squares indicate apomorphic grades,

empty squares plesiomorphic grades. Synapomorphies are indicated by darker stippling. The

following characters are referred to and are indicated by the number to the right of the linked

apomorphic and plesiomorphic grades (a, apomorphic grade; p, plesiomorphic grade. Cannula,

and lateral, caudal, and mesial processes refer to the endopodial armature of the male second

pleopod; endopod also refers to this appendage): 1, lateral process greatly extended (a) or not

(p); 2, propodus of male first peraeopod with large triangular process on palm or having

secondarily lost this (a) or primitively without such a process (p); 3, male first pleopod distinctly

longer than second, with an elongate distal segment having long plumose spines on distal margin

(a) or male first pleopod shorter or more or less subequal in length to second and lacking plumose

distal spines (p); 4, endopod displaying torsion (a) or not (p); 5, tip of endopod coiled spirally

(a) or not (p); 6, caudal process dentate (a) or not (p); 7, mesial process sclerotized and either

rugose or dentate (a) or simple and rounded (p); 8, mesial process dentate (a) or not (p);

9, lateral process heavily sclerotized (a) or not (p); 10, uropoda very short (a) or of moderate

length (p); 11, mesial process well developed (a) or not (p); 12, cannula long and narrow (a) or

short and wide (p); 13, caudal process well developed with associated setae on dorsal surface (a)

or not well developed and lacking such setae (p); 14, male first pleopod reduced (a) or not (p);

15, mesial process prominent (a) or less well developed (p); 16, caudal process present (a) or

absent (p); 17, cannula long and narrow (a) or short and wide (p).
NUMBER 49 77

would have been considerably less. I would like to extend my sincere appreciation to all the following who

either gave or loaned me specimens: Dr. J. B. Anderson, United States Department of the Interior; Dr.

N. H. and Margaret Anderson, Oregon State University; Dr. W. M. Beck, Jr., Florida State Board of

Health; Mr. J. Bishop, University of Waterloo; Miss

A. B. Bliss, Museum of Comparative Zoology, Harvard

University; Dr. R. O. Brinkhurst, University of Toronto; Dr. E. L. Bousfield, National Museum of Canada, Ottawa; Dr. T. E. Bowman, National Museum of

Natural History, Washington, D.C.; Dr. G. A. Cole,

Arizona State University; Prof. J. S. Dendy, Auburn

University; the Director, Great Lakes Institute, Toronto; Mr. S. Herrman, University of Colorado; Dr.

J. K. Hiltunen, United States Department of the Interior; Prof. H. B. N. Hynes, and Mr. N. Kaushik,

University of Waterloo; Dr. L. A. Krumholz, University of Louisville; Dr. G. H. Lauff, Kellogg Biological Station; Dr. H. W. Levi, Museum of Comparative

Zoology, Harvard University; Mr. R. L. Lippson,

Kellogg Biological Station; Dr. W. G. Moore, Loyola

University; Dr. C. G. Paterson, University of Waterloo; Dr. S. B. Beck, Museum of Comparative Zoology,

Harvard University; Prof. R. W. Pennak, University

of Colorado; Dr. R. Prins, Clemson University; Dr.

W. A. Shear, Concord College; Dr. J. D. Unzicker,

Illinois Natural History Survey; Dr. T. F. Waters,

University of Minnesota; Dr. A. A. Weaver, the College of Wooster; and Dr. G. B. Wiggins, Royal Ontario

Museum, Toronto. I would also like to thank the

following colleagues who provided information concerning the whereabouts of type material or other matters: Miss A. B. Bliss; Dr. E. L. Bousfield; Dr. T. E.

Bowman; Dr. G. E. Clothier, Sonoma State College;

Mr. C. W. Hart, the Academy of Natural Sciences of

Philadelphia; Prof. H. B. N. Hynes; Dr. L. A. Krumholz, Dr. H. W. Levi; Dr. G. E. Lindsay and Mr. D.

Chivers, both at the California Academy of Sciences

in San Francisco; Dr. R. Prins; Dr. Ulrich R0en,

University of Copenhagen; Dr. W. N. Rosine, Augustana College; Dr. E. H. Smith, Pacific Marine Station;

Dr. P. W. Smith, Illinois Natural History Survey;

Dr. R. I. Smith, University of California, Berkeley;

and Dr. J. D. Unzicker.

The manuscript was criticized by Dr. E. L. Bousfield and Dr. T. E. Bowman; my thanks are offered

for their helpful comments. I wish also to express my

appreciation to my wife and Mrs. T. McConnell who

were responsible for the typing of the manuscript.

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of North America. Proceedings of the United States

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727.

Roen, U. I.

1962. Studies on Freshwater Entomostraca in Greenland.

II. Meddelelser om Grenland, 170:1-249.

Sars, G. O.

1899. An Account of the Crustacea of Norway with Short

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Say, T.

1818. An Account of the Crustacea of the United States.

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Smith, S. I.

1874. The Crustacea of the Fresh Waters of the United

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Smith, S. I., and A. E. Verrill

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Index

[Names of new species in italics, page numbers of principal accounts in boldface]

Asellopsis, 73

Asellus, 1, 2, 3, 4, 14, 16, 17, 33, 34, 38, 41, 42, 45, 55, 56,

60, 63, 68, 73, 74, 75, 76

"alabamensis," 74

aquaticus, 1, 41, 42 (fig.), 74

attenuatus, 1, 3, 16, 17, 30, 31, 32 (fig.), 33 (fig.), 34,

36, 38, 45, 46 (fig.), 48, 53, 58, 61, 66, 68, 71, 75,

76 (fig.)

bivittatus, 1, 18, 23

brevicauda, 1, 3, 18, 19, 22, 75, 76 (fig.)

brevicauda bivittatus, 16, 17, 22 (fig.), 23 (fig.), 24, 74

brevicauda brevicauda, 16, 17, 19, 20 (fig.), 21 (fig.),

22 (fig.), 23 (fig.), 24, 25, 29, 74

brevicaudus, 18, 19

communis, 1, 2, 3, 4, 5, 6 (fig.), 7 (fig.), 8 (fig.), 10

(fig.), 11 (fig.), 12 (fig.), 13, 14 (fig.), 15 (fig.), 16,

17 (fig.), 19, 25, 36, 38, 42, 43, 45, 46, 57, 73, 74,

75, 76 (fig.)

conestogensis, 1

dentadactylus, 1, 3, 14 (fig.), 16, 17, 34, 35 (fig.), 36,

38, 75, 76 (fig.)

forbesi, 3, 16, 17, 45, 50, 52 (fig.), 53, 54 (fig.), 55

(fig.), 56 (fig.), 57, 60, 61, 75, 76 (fig.)

gronlandicus, 41

hoppiae, 73

hoppinae, 73

incisus, 73

intermedius, 1, 3, 5, 16, 17, 18, 24, 25, 26 (fig.), 27

(fig.), 28 (fig.), 29 (fig.), 30 (fig.), 45, 57, 71, 74, 75,

7C (fig.)

kenki, 1, 3, 16, 17, 38, 39 (fig.), 40 (fig.), 41 (fig.), 75,

76 (fig.)

laticaudatus, 3, 16, 17, 22 (fig.), 61, 62 (fig.), 63 (fig.),

64 (fig.), 75, 76 (fig.)

lineatus, 42, 73

militaris, 1,4,5,24,25,57

montanus, 1, 3, 14 (fig.), 16, 17, 36, 37 (fig.), 74, 75,

76 (fig.)

nodulus, 3, 16, 17, 41 (fig.), 66, 67 (fig.), 69 (fig.), 74,

75, 76 (fig.)

obtusus, 3, 16, 17, 53, 55 (fig.), 57, 58 (fig.), 59 (fig.),

60 (fig.),66, 68, 74, 75, 76 (fig.)

occidental, 3, 13, 16, 17, 69, 70 (fig.), 71 (fig.), 72

(fig.), 73, 74, 76 (fig.)

racovitzai, 3,5, 13, 34, 42,43, 75, 76 (fig-)

racovitzai australis, 16, 17, 43, 46 (fig.), 47, 49 (fig.),

50 (fig.), 51, 74

racovitzai racovitzai, 16, 17, 43, 44 (fig.), 45, 46 (fig.),

47 (fig.), 50, 51, 73, 74

scrupulosus, 3, 16, 17, 41 (fig.), 64, 65 (fig.), 66 (fig.),

68, 75, 76 (fig.)

stygius, 1

tenax, 73

tomalensis, 1, 72, 73

tridentatus, 1

vulgaris, 41,42

Baicaloasellus, 2

Conasellus, 2

Lirceus, 2, 73

hoppinae, 73

hoppinae hoppinae, 73

lineatus, 42, 73

Mancasellus, 73

Mesasellus, 2

Oniscus aquaticus, 41

o

80


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