WATER POLLUTION CONTROL RESEARCH SERIES • 18050 ELDO5/72
BIOTA OF FRESHWATER
ECOSYSTEMS

Identification
Manual
FRESHWATER
ISOPODS
(ASELUDAE)
OF NORTH
AMERICA
U.S. ENYmOHMEKWI PROTECTION AGENCY

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         Biota of Freshwater Ecosystems


           Identification Manual No. 7
FRESHWATER ISOPODS  (ASELLIDAE) OF  NORTH AMERICA
                        by

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

          ENVIRONMENTAL  PROTECTION AGENCY
                 Project  #  18050 ELD

                 Contract # 14-12-894
                      May 1972
For sale by the Superintendent of Documents, U.S. Government Printing Office
              Washington, D.C. 20402 - Price $2.50
                  Stock Number 5501-0390

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                    EPA Review Notice

      This report has been reviewed  by  the  Environ-
      mental Protection Agency, and  approved  for
      publication.  Approval does  not signify that
      the contents necessarily reflect  the  views
      and policies of the EPA, nor does mention of
      trade names or commercial products  constitute
      endorsement or recommendation  for use.
          WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Series describes the
results and progress in the control and abatement of pollution
in our Nation's waters.  They provide a central source of
information on the research, development, and demonstration
activities in the water research program of the Environmental
Protection Agency, through inhouse research and grants and
contracts with Federal, State, and local agencies, research
institutions, and industrial organizations.

Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Chief, Publications Branch
(Water),  Research Information Division, R&M, Environmental
Protection Agency, Washington, DC  20460.
                            11

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                           FOREWORD
"Freshwater Isopods (Asellidae) of North America" is the
seventh of a series of identification manuals for selected
taxa of invertebrates occurring in freshwater systems.  These
documents, prepared by the Oceanography and Limnology Program,
Smithsonian Institution for the Environmental Protection
Agency will contribute toward improving the quality of the
data upon which environmental decisions are based.

Additional manuals will include but not necessarily be lim-
ited to, freshwater representatives of the following groups:
amphipod crustaceans (Gammaridae), branchiuran crustaceans
(Argulus*), decapod crayfish crustaceans (Astacidae), leeches
(Hirudinea), polychaete worms (Polychaeta), freshwater plan-
arians (Turbellaria), aquatic dryopoid beetles (Dryopoidea)
and freshwater clams (Sphaeriacea).
                             ill

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                                ABSTRACT
A key is given to the North American genera (Asellus and Lirceus') of
asellid isopods.  Another key is provided for the surface-living species
of Asellus but lack of clear, published morphological distinctions in
the genus L-ivoeus prevents the construction of a key for that genus.
Notes on ecology, collection, preservation and identification are also
included.

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                                 CONTENTS






Section                                                              Page




 I     Introduction                                                    1




          Collecting and Preservation                                  3




          Identification                                               4




 II    Species List and Distribution                                  13




 III   Key to Genera of North American Freshwater Asellidae           17




 IV    Key to North American Surface-living Species of Asellus        19




 V     References                                                     43




 VI    Index of Scientific Names                                      45
                                   VII

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                                 FIGURES
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
Dorsal view of male Asellus oomrunis and Lirceus sp.
Anterior head appendages of A. oommunis
Posterior head appendages of A. communis
Peraeopod 1 of A. oommun-is
Peraeopods 2-7 of A. aommunis
Pleopods 1 and 2 of A. communes
Pleopods 3-5, uropod and telson of A. communis
Dorsal view of head of Liroeus sp. and Asellus sp.
Pleopod 3 of Liraeus sp. and Asellus sp.
Various appendages of A. oaaidentalis
Endopod of pleopod 2 of. A.  ocaidentalis
                   of A. latieaudatus
                   2 of. A.  laticaudatus
                     of A.  Gommunis
                         intermedius
                     of A.  intermedius
                         attenuatus
                         raoovitzai racowitzai
                           raaovitzai racovitzai
                           racovitzai
Various appendages
Endopod of pleopod 2
Endopod of pleopod 2
Various appendages of A
Endopod of pleopod 2
Various appendages
Various appendages of A.
Endopod of pleopod 2 of A.
Pleopod 1 of A.  raoovitzai
of A.
Various appendages of A. raoovitzai australis
Endopod of pleopod 2 of A. raaovitzai australis
Various appendages of A. forbesi
Endopod of pleopod 2 of A. forbesi
Endopod of pleopod 2 of A. forbesi
Peraeopod 1 of A. obtusus
Various appendages of A. obtusus
Endopod of pleopod 2 of. A. obtusus
Various appendages of A. montanus
Various
Various
        appendages
        appendages
of A.
of A.
Various appendages of A.
nodulus
dentadaotylus
brevicauda breviaauda
Pleopod 2 of A. brevioauda brevioauda
Various appendages of A. sorupulosus
Endopod of pleopod 2 of. A. scrupulosus
Various appendages of A. kenki
Page

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                                   Vlll

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                                 TABLES


                                                                    Page

1   Differences between Asellus raoovitzai raoovitzai and A.
       racovitzai australis                                          28

2   Differences between Asellus forbesi and A.  obtusus               34

3   Differences between Asellus bvevloauda brevioauda and A.
       bvevioauda bivittatus                                         40

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                                 SECTION I

                               INTRODUCTION

The Asellidae are the most important surface-living freshwater isopods
in North America.  The other isopod families which occur in North Ameri-
ca,  Bopyridae, Sphaeromatldae (formerly Sphaeromidae), and Cirolanidae,
are much less important.  The Bopyridae are parasitic forms, and the
Cirolanidae are spring or underground forms occurring in Mexico, areas
immediately to its north, and Virginia.  The Sphaeromatidae, otherwise a
predominantly marine family^ includes several species found in fresh to
brackish waters near the coast and in hot springs.  Sphaeromatids and
cirolanids are easily recognised by their uropods which are attached
anterolaterally to the abdomen, and not, as in asellids, posteriorly or
posterolaterally.  None of these additional isopod families, all of
whose representatives are only rarely or occasionally encountered in sur-
face fresh waters of North America, is considered further in this publi-
cation.

The North American fauna of the Asellidae is not well-known, but Williams
(1970) has revised the systematics of the surface-living species of
Asellus, the principal genus, and the ecology of some asellids of known
identity has also been studied recently (e.g. Ellis, 1961, 1971; Clifford,
1966; Styron, 1968; Seidenberg, 1969).

For the purposes of this report, North American asellids are considered
to be represented by two genera, Liroeus and Asellus.  Other generic
names that have been applied include Asellops-is, Manoaselluss and
Caeci-dotea.  All species of these are now regarded as either species of
LiToeus (j=Asellopsis3 Mancasellus') or Asellus (^CaeQ-tdotea).  It has re-
cently been proposed (Henry and Magniez, 1968, 1970) that North American
Asellus species be divided between the genera Conasellus, Asellus (of
restricted definition), and Pseudobaioalasellus.  Of these, the first
two represent the elevation of former 'subgenera'  to generic rank, and
the latter a newly proposed genus.  It may well be that North American
asellids will prove to be a group that should legitimately be regarded
as representing several genera, but as the proposals of Henry and Magniez
were published before adequate taxonomic consideration had been given
surface-living species of North American asellids, and before systematic
knowledge of surface-living and underground species has been integrated,
such proposals seem decidedly premature to the present author.  In order
not to perpetuate at generic level the sort of confusion that has exis-
ted in part at 'subgeneric' level in North American asellids (see
Williams, 1970, p. 2), the most practical procedure for the moment is to
regard all North American species as referable to two genera only,
Asellus as defined by Birstein (1951, p. 51), and Lireeus.  The former
contains both surface-living and underground species;  species of the
latter typically live in surface waters only.

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Lirceus was revised taxonomically by Hubricht and Mackin (1949) who in-
cluded a key, but the revision is not entirely satisfactory in that con-
siderable emphasis was placed upon a number of apparently diagnostic
characters which in fact are subject to great variation and intergrada-
tion between species (Styron, 1969).  The genus, according to Hubricht
and Mackin (1949), lacks the sort of singular characters provided for
Asellus by the structure of the male sexual pleopods (see below), and
species recognition is based upon the evaluation of many characters.  In
the interests of providing some useful indications of the ecological and
geographical distributions of Livoeus species as described, a summary of
relevant data, abstracted mainly from Hubricht and Mackin (1949), has
been compiled and is given following the similar summary for Asellus com-
piled from Williams (1970) (see Species List and Distribution below), but
no attempt is made to provide a key for their identification here.

The ecological status of Asellus in North America is not clear.  In most
of Europe, Asellus (as A. aquatious L.) is characteristically present
within given sections of organically polluted rivers.  Kolkwitz and Mar-
sson (1909) noted that it is one of the organisms abundant in the so-
called a-mesosaprobic polluted zone in particular but also occurs in the
g-mesosaprobic zone (the 'a- and g-mesosaprobic zone' proposed by
Kolkwitz and Marsson (1909)  may be regarded as roughly equivalent to the
 'recovery zone' of several American water pollution biologists), and
Hynes (1960)  noted that Asellus is a member (with tubificids and chiron-
omids)  of the 'pollution fauna' in the badly polluted zone of rivers
affected by organic wastes.   Many investigators of North American pollu-
ted rivers make no reference to the genus in published accounts of results,
whereas others do indicate its occurrence in organically polluted rivers;
Bartsch (1948) and Bartsch and Ingram (1959), for example,  indicated that
it is characteristic of the 'zone of recovery'.  In part, some of this
ecological uncertainty may be a reflection of the formerly unclear syste-
matic position of surface-living forms.

Because this key to Asellus has been prepared for use by biologists con-
cerned with investigating pollution of inland waters, only surface-living
forms are discussed.   Neither this key nor the more detailed account of
Williams (1970) should be regarded as definitive;  undoubtedly much re-
mains to be discovered concerning the systematics of North American asel-
lids.  It is felt, nevertheless, that the key does deal with those species
that are most likely to be encountered.

North American species alone are considered, i.e. species occurring in the
United States and Canada.  Asellids are known from Mexico (Cole and
Minckley, 1968),  but are not considered here.

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                        COLLECTING AND PRESERVATION

A variety of methods may be used to collect specimens for qualitative
purposes.  None requires elaborate apparatus or an involved technique;
freshwater asellids are easily-seen, macroscopic animals that are rela-
tively slow-moving, do not swim, and dwell amongst submerged vegetation
and bottom detritus.  They are not conspicuous burrowers, although they
may often occur on the undersurfaces of submerged stones.

The most straightforward method is the direct removal by the investiga-
tor of small amounts of submerged vegetation or bottom material either
by hand or using a fine-meshed (scrim) dipnet or pondnet followed by the
searching of this material for specimens.  If asellids occur they may be
handled by gripping the middle of their body with a pair of blunt forceps
held at right-angles to the long axis of the body.  Searching may be
facilitated by placing the vegetation or other material to be examined
into a white, shallow dish or tray containing water to a depth of about
one inch.  A tray normally used by the author measures 8 x 10 x 3 inches.
If the material is slightly teased apart after being placed in the tray
and is then undisturbed for a minute or so, specimens often become con-
spicuous by their slow movements amongst the material or by their move-
ment from the material towards clear areas of water in the tray.  Such
specimens may also be removed by forceps, but a better, less damaging
method is to suck them gently with some water into a glass tube (diameter
about 3/8 inch) in which suction is maintained by a rubber bulb attached
to one end.  A little practice on the part of the operator is required
with this tube method of handling specimens for satisfactory performance.
Asellids may also often be collected by removal of submerged stones and
the examination of their lower surfaces.

Specimens are best killed and preserved by directly placing them in 70-
80% ethyl alcohol.  Transference to fresh alcohol after a few days is re-
commended.  Care should be exercised to ensure that crowding of preserved
specimens does not occur, and that tubes are adequately labelled.  The
maintenance of live specimens is not required for species identification.

It should be stressed that reasonably large collections are necessary for
adequate systematic examination since species identification (for both
Asellus and L-irceus} is based on adult males only, and more than one
species may occur in the same collection.  Liraeus and Asellus may also
occur together.  It is suggested that 25 specimens be regarded as the min-
imal adequate number for one collection, although, of course, smaller
collections will often be useful also.

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                              IDENTIFICATION

For generic separation of Lirceus and Asellus and for species identifica-
tion of Asellus it will be necessary in using this publication to be
familiar with the conformation of and the terminology applied to at least
certain parts of the external structure of asellids.  For confirmation of
species identity by reference to the original description or to a complete
description given elsewhere, a similar familiarity will be required with
regard to most of the remaining body parts.   Before discussing the actual
technique of specimen examination, it is appropriate therefore to describe
briefly the morphology of a typical species.  Asellus eommunis has been
selected for this purpose.
   Fig. 1.  A, dorsal view of male Asellus communis;  B,  dorsal view
   of male Lirceus sp.  Drawn from preserved specimens.   Original.
   a.=abdomen, h.=head, t.=thorax.

There are three major body regions, the head,  thorax,  and abdomen (Fig.  1)
The head and abdomen appear unsegmented, whereas the  thorax is divided
into seven segments.  Each region bears a number of appendages projecting
either anteriorly, posteriorly, ventrally or laterally.

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   Fig. 2.  A. aommun-Ls: A, first antenna; B, second antenna; C, upper
   lip; D, lower lip.  From Williams  (1970).

Anteriorly, the head bears a pair of  short antennae (first antennae or
antennules) and a pair of much longer ones (second antennae or, simply,
antennae)  (Fig. 2A, B).  Ventrally the head bears a mouth which has an
upper  (or  anterior) lip or flap and a bilobed, lower (or posterior) lip
(Fig.  2C,  D).  Posterior to the mouth  is a paired series of small
appendages used in feeding;  from front to back these are respectively
the mandibles, first maxillae (or maxillules), second maxillae (or-
simply, maxillae), and maxillipeds (Fig. 3A-F).  In addition the head
has a pair of small eyes;  these occur dorsally, one on each side
(Figs  1A,  8B).

Each segment of the thorax is dorsoventrally flattened and bears lat-
erally a leg or peraeopod (pereiopod or pereopod);  in all there are
seven pairs (Fig. 1A).  There are some differences in structure between
each pair of legs, but these are not great, and only the structure of
the first pair of legs of adult males is distinctly different in that
the two most distal leg segments are expanded to form a claw-like appa-
ratus  (Figs 4A,B; 5A-F).  The palm of this usually bears near its mid-
point a prominent triangular projection and proximally a few tooth-like
setae  (Fig. 4A).  Each leg consists of six apparent segments, termed
respectively the dactylus, propodus, carpus, merus, ischium and basis
of which the dactylus is the most distal.  A seventh leg segment, the

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Fig. 3.  A.  oommunis: 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.  From Williams  (1970).

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   Fig. 4.  A. oomrmn-Ls: A, dactylus and palm of first peraeopod; B,
   first peraeopod.  From Williams (1970).

coxa, is not distinct from the thorax.  Dorsally, the thorax is covered
by a tergal plate, which in the second to seventh segments is expanded
to a small lobe at each anterolateral angle.  Breeding females bear
ventrally a series of flaps, oostegites, which arise from near the in-
side of the base of the anterior legs and form a brood-pouch or marsu-
pium.  In non-breeding females, their place is taken by small, club-
shaped structures.  In males, a pair of tube-like penes arise from the
posterior, ventral margin of the last thoracic segment;  the penes pro-
ject backwards.

The abdomen is conspicuously dorsoventrally flattened.  In males, five
pairs of pleopods are borne ventrally, of which the anterior two pairs
are small and serve a sexual function (Fig. 6A, B).   The remaining pleo-
pod pairs (3-5, Fig. 7A-C) are large, plate-like, and serve a respira-
tory function;  each of these pleopods consists of a larger, more robust
and variously setose lower plate (exopod), and a smaller, fragile, non-
setose  upper (or inner) plate (endopod).  In females, only four pairs
of pleopods occur (the true first pair are always absent) of which the
most anterior pair consists of small and simple triangular plates,
whilst the remaining three pairs are similar to those in males.

Of greatest importance in the identification of Asellus species is the
structure of the first and second male pleopods, and of critical impor-
tance is the conformation and shape of the tip of the endopod of the
second pleopod;  especially marked variation between species is dis-
played in the structure of the endopod tip.  It is for this reason that
these appendages are discussed further below firstly for A. communis in
particular, and secondly, with respect to the conformation of the tip of
the endopod of the second pleopod alone, for all North American species
of Asellus in general.

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   Fig. 5.  A.  eommuniSf peraeopods:   A, second; B, third; C, fourth;
   D, fifth; E, sixth; F, seventh.  From Williams (1970).

The first pleopod of the male (Fig. 6A)  consists of two segments, a basal
sympod and a distal segment.  The second pleopod (Fig. 6B) consists of a
large sympod bearing distally a two-segmented exopod (outermost structure)
and an unsegmented endopod (innermost structure) (Fig. 6C).   The endopod
has two laterally projecting lobes basally; inner and outer apophyses.

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From near the distal tip of the endopod (Fig. 6D, E) projects a tube-like
cannula, whilst the distal edge of the endopod itself gives rise to a
rounded lobe, the caudal process.  This conformation of endopod tip is
unique to A. eommunis.  It, and that for other North American species of
                                                      v. g.
               D
   Fig. 6.  A.  cormunis:  A, first pleopod; B, second pleopod;  C,  dorsal
   surface of endopod of second pleopod; D,E, respectively dorsal  and
   ventral surfaces of tip of endopod of second pleopod.   (After Williams,
   1970).
   can.=cannula, c.p.=caudal process, v.g.=ventral groove.

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Fig. 7.  A.  communis:  A, third pleopod; B, fourth pleopod;  C,  fifth
pleopod; D,  uropod; E, uropod and telson.   From Williams (1970).

                                10

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Ase11us3 appears to be derivable from a structure consisting in principle
of a terminal ventral groove associated with which are four terminal ele-
ments:  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 from the lateral edge of the groove;
and a terminal caudal process.  Loss or modification <^f. these elements,
it has been suggested, can produce the conformation unique for each species
of Asellus.

A final pair of abdominal appendages project backwards from the posterior
border of the abdomen;  these appendages are the uropods.  Each (Fig. 7D)
consists of a basal segment, the peduncle, and two distal segments or rami,
an inner one, the endopod, and an outer one, the exopod.  The upper sur-
face of the region referred to here as the abdomen in effect constitutes
the telson, also referred to as the pleotelson (Fig. 7E).

EXAMINATION TECHNIQUE.  A stereoscopic and a compound microscope, a pair
of fine forceps, a mounted needle, a petri-dish (or similar container) and
microscope slides and coVerslips are equipment needed for species identifi-
cation.  Preliminary examination and dissection should be made using the
stereoscopic microscope with the specimens immersed in 70-80% ethyl alcohol
and illuminated by reflected light against a dark background.  Further
identification is carried out by removing appropriate appendages or body
parts, mounting these on a microscope slide in a small amount of the alco-
hol from which they were withdrawn, and examining by transmitted or re-
flected light as appropriate.  Such preparations are temporary;  more per-
manent ones may be made using one of several mounting reagents now com-
mercially available which do not require passage of specimen material through
a series of other reagents.  The author uses "Euparol" (George Gurr Ltd.,
U.K.).  Readers are warned, however, that many such mounting reagents also
include clearing agents and if their action is too severe distortion and
contraction of mounted material (particularly of the endopod tip of the
second pleopod of male Asellus specimens) may occur.  It is important that
this does not happen.  Readers are also warned that endopod tips of the
second pleopod of male Asellus specimens should be viewed in a variety of
positions so that a better appreciation of the arrangement of terminal
parts is gained.
                                     11

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                             SECTION II

                   SPECIES LIST AND DISTRIBUTION

It is stressed that our knowledge of species distributions is still in-
complete so that the notes below on this subject are to be regarded as
summaries of known distributions not actual distributions.

                          Genus Asellus

Asellus attenuatus Richardson, 1900.  Known only from one locality,
     Dismal Swamp, Virginia  (see Richardson, 1901).
Asellus brevieauda brevicauda Forbes, 1876.  Springs and spring-fed
     streams in large but relatively restricted area of east-central
     United States:  Arkansas, Illinois, Kentucky, Missouri.
Asellus brevicauda bivittatus Walker, 1961.  Known only from one
     locality, Doe Run, a spring-fed creek in Kentucky.
Asellus eorrmmis Say- 1818.  Creeks, rivers, ponds, lakes, reser-
     voirs, occasionally in  swamps.  Not present in the Great Lakes.
     Mainly distributed in northeastern United States and south-
     eastern Canada, but has also been recorded from Colorado and
     Washington,  Complete list of States and Provinces:  Colorado,
     Maine, Maryland, Massachusetts, New Jersey; Pennsylvania,
     Vermont, Washington, West Virginia; Nova Scotia, Ontario.
Asellus dentadaatylus Mackin and Hubricht, 1938.  Small creeks in
     Arkansas and Louisiana.
Asellus forbesi Williams, 1970.  Typically in temporary ponds, flood
     pools, and sloughs, but also in marshes, small creeks, and
     occasionally lakes.  Has been collected from Lake Huron at a
     depth of 15 meters.  Distributed over very large area of east-
     central United States and in southern Ontario.  Complete list
     of States and Provinces:  District of Columbia, Indiana, Iowa,
     Kentucky, Maryland, Michigan, Missouri, North Carolina, Ohio,
     South Carolina, Virginia, West Virginia, Ontario.
Asellus intermedius Forbes,  1876.  Typically in running waters (creeks,
     streams and rivers), but also in springs, ditches, ponds, lakes.
     Large area of east-central United States and southern Ontario:
     Illinois, Indiana, Iowa, Kentucky, Michigan, Missouri, Wisconsin;
     Ontario.
Asellus kenki Bowman, 1967.  Springs and spring-fed creeks (not in
     large streams and ponds) in small area near Washington, D. C.:
     District of Columbia, Maryland, Pennsylvania, Virginia.
Asellus lat-Leaudatus Williams, 1970.  Small creeks and ponds in south-
     eastern United States:  Kentucky, Louisiana.
Asellus montanus Mackin and Hubricht, 1938.  Creeks, streams, sloughs
     in Arkansas and Oklahoma.
Asellus nodulus Williams, 1970.  Swamps, roadside ditches, streams, and
     spring outlets in Maryland.
                                    13

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Asellus obtusus Williams, 1970.  Swamps, roadside ditches, temporary ponds,
     rivers, small streams in small region of southeastern United States:
     Florida, Georgia, Louisiana.
Asellus occidentalis Williams, 1970.  Spring-brooks, streams, rivers,
     marshy edges of lakes in far northwestern United States and extreme
     southwestern Canada:  Oregon, Washington; British Columbia.
Asellus racovitzai racovitzai Williams, 1970.  Creeks, rivers, ponds,
     swamps, small lakes, and great Lakes down to 42 meters.  Mainly dis-
     tributed in northeastern United States and southeastern Canada, but
     has also been recorded from Washington.   Complete list of States
     and Procinces:  District of Columbia, Indiana, Maryland, Massachusetts,
     Michigan, Vermont, Washington; Ontario,  Quebec.  It is the dominant
     Great Lakes species except for Lake Michigan from where it is still
     unrecorded (see Racovitza, 1920)
Asellus racovitzai australis Williams,  1970.   Creeks and rivers in south-
     eastern United States:   Florida, Georgia.
Asellus scrupulosus Williams, 1970.  Vernal and woodland pools in West Vir-
     ginia.

                              Genus Lirceus

Lirceus alabamae Hubricht and Mackin, 1949.  Seeps and springs in Alabama.
Lirceus bicuspidatus Hubricht and Mackin, 1949.  Springs, seeps, creeks,
     and streams in Arkansas.
Lirceus bidentatus Hubricht and Mackin, 1949.  Known only from a seep in
     Arkansas.
Lirceus brachyurus (Harger,  1876).  Springs and small streams of Atlan-
     tic drainage from northeastern Pennsylvania to northern Virginia:
     Pennsylvania, Virginia.
Lirceus fontinalis Rafinesque, 1820.  Typically in springs but also in
     drain outlets, seeps and streams:   Georgia, Illinois, Indiana, Ken-
     tucky, Ohio, Tennessee.
Lirceus garmani Hubricht and Mackin, 1949.  Springs, seeps, creeks,
     streams (sometimes temporary) and ponds  (also sometimes temporary)
     in Arkansas, Kansas, Missouri, Oklahoma.
Lirceus hargeri Hubricht  and Mackin, 1949.  Springs in Tennessee and
     Virginia.
Lirceus hoppinae hoppinae (Faxon, 1889).  Springs in Missouri (see
     Carman, 1889) .
Lirceus hoppinae ozarkensis Hubricht and Mackin, 1949.  Springs and
     sometimes streams in Missouri and northern Arkansas.
Lirceus hoppinae ouachitaensis (Mackin and Hubricht, 1938).  River tri-
     butaries in Oklahoma.
Lirceus lineatus (Say, 1818).  Rivers,  creeks, sloughs, swamps, lakes
     including Great Lakes.   Distributed in Great Lakes region and
     southeastern United States from Virginia to Florida and Alabama.
     Complete list of States and Provinces:  Alabama, Florida, Georgia,
     Illinois, Indiana, Michigan, New York, South Carolina, Tennessee,
     Virginia; Ontario.
                                   14

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Lireeus louisianae (Mackin and Hubricht, 1938).  Spring-fed marshes,
     temporary pools, sloughs, roadside ditches, small streams, seeps:
     Arkansas, Illinois, Louisiana, Missouri.
LiToeus megapodus Hubricht and Mackin, 1949.  Springs in Missouri.
Liraeus riahardsonae Hubricht and Mackin, 1949.  Known only from a drain
     outlet in Ohio.
        tr-ilobus Hubricht and Mackin, 1949.  Known only from woodland
     pools in Oklahoma.
                                    15

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                               SECTION  III

          KEY TO GENERA OF NORTH AMERICAN FRESHWATER ASELLIDAE
   Lateral margin  of head produced  to  form  thin plate  covering or over-
     hanging base of mandible,  this plate  frequently  but not always
     incised  (Fig. 8A) .  Anterior  margin of head with pointed median
     protuberance (carina)  between bases of antennules  (Fig. 8A).
     Distal segment of exopod  of pleopod 3 (outer gill  operculum)
     approximately hemispherical in shape, with division between it
     and proximal segment running  obliquely backwards from  inner
     distal angle (Fig. 9A) :                          Livaeus Rafinesque
     (species  not identified here; see Introduction)
   Lateral margin  of head not produced to cover or overhang  base of man-
     dible  (Fig.  8B).   Anterior margin of  head without  a median protu-
     berance between bases  of  antennules  (Fig. 8B).   Distal segment of
     exopod of pleopod 3  (outer gill  operculum) sub-quadrangular in
     shape, division between it and proximal  segment  running approxi-
     mately at right-angles to long axis of specimen  and commencing
     well anterior to  inner distal angle of appendage (Fig. 9B):
                                           Asellus St.  Hilaire  (page 19)
Fig. 8.  Dorsal view of
head:  A, Liraeus sp.;
B, Asellus sp. Original
ca.=carina, e.=eye.
Fig. 9.  Third pleopod:  A, Liroeus
sp.; B, Asellus sp.  Original.
                                   17

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Fig. 10.  A,  oooidentdlis.   A, dactylus and propodus of first peraeo-
pod;  B, first pleopod;  C, second pleopod;  D, E, respectively dar-
sal and ventral surfaces of tip of endopod of second pleopod;  F, uropod;
G, uropod and telson.  (After Williams, 1970).
can.= cannula, l.p.= lateral process, v.g.= ventral groove.
                                   18

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                                SECTION IV

          KEY TO NORTH AMERICAN SURFACE-LIVING SPECIES OF ASELLUS


The following key is of use only for adult male specimens;  as indicated
in the text above, it is the males which in Asellus provide the diagnos-
tic characters for the species separation.  Females cannot be identified
at present.  In the key, the terms mesial process, lateral process,
caudal process, ventral groove, and cannula refer to structures at the
tip of the endopod of the second pleopod.  All drawings of the first and
second pleopods, unless contraindicated, are of right pleopods.  With
respect to the surface of these, ventral=anterior, and dorsal=posterior.
All principal distinguishing characters have been used in compiling the
key, and are illustrated in the accompanying figures (no direct refer-
ence may be made to such characters in the final part of the couplet for
each species) .  In certain cases, to aid identification some quantitative
data are given in tabular form.

1     Palm of propodus of peraeopod 1 lacking triangular process near
         midpoint, but with 3-5 teeth-like spines variously arranged
         (Fig. 10A).  Pleopod 1 distinctly longer than pleopod 2, dis-
         tal segment with numerous long plumose setae (Fig. 10B).  Pleo-
         pod 2 with mesial and caudal processes not developed, but lat-
         eral process large, projecting beyond cannula, and distally
         recurved (Figs 10D, E, 11A-E);  endopod shape and relative pro-
         portions of segments as in Fig. IOC.  Both exopod and endopod
         of uropod longer than peduncle (Fig. 10F, G):    A.  oocidentalis
      Palm of propodus of peraeopod 1 usually (not always) with both
         a large triangular process near midpoint and some teeth-like
         spines variously arranged.  Pleopod 1 either longer than
         pleopod 2 and distal segment with numerous long plumose
         setae,  or shorter to subequal in length to pleopod 2 and
         lacking distal plumose  setae.   Lateral process of pleopod 2
         either absent or developed in conjunction with mesial process
         (i. e. not as shown in Figs 10D, E, 11A-H);  endopod shape
         and relative proportions of segments more or less dissimilar
         to those shown in Fig. IOC.  Exopod of uropod typically
         shorter than peduncle, endopod usually subequal in length
         to peduncle (but sometimes longer) 	 2

2(1)  Pleopod 1 usually subequal in length to pleopod 2 or distinctly
         shorter, distal segment subovate to subrectangular without
         long plumose setae on distal margin but with few to numerous
         short simple setae.   Pleopod 2 with prominent cannula,
         often wide, never hidden ventrally by lateral or mesial
         processes 	 3
      Pleopod 1 usually distinctly longer than pleopod 2, distal
         segment usually subovate, often curved outward, and with
         few to numerous long plumose setae on distal margin.  Pleopod
         2 with small, narrow cannula sometimes hidden ventrally by
         lateral or mesial processes 	 10

                                    19

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   Fig. 11.   A.  oocidentalis.   Variation in morphology of tip of
   endopod of second pleopod.   A-E,  ventral views;  F-H,  dorsal
   views.   From Williams (1970).

3(2)   Pleopod 2 with neither mesial  nor caudal  processes developed,
         only cannula projects distally from endopod tip (Figs 12D,
         E,  13A-F);   dorsal surface  of distal end of endopod with
         numerous minute comb-like structures (Fig.  12D);   endopod
         shape and proportion  of segments as in Fig.  12C.   Both rami
         of uropod always flat, lanceolate and  broad (Fig.  12F, G):
                                                         A.  lat-ioaudatus
      Caudal process of pleopod 2 always more or less developed, mesial
         process either developed or not, cannula never only process
         to project distally from endopod tip;   dorsal surface of dis-
         tal end of endopod usually  lacking minute comb-like struc-
         ture (if present, these extend on to caudal process);  endo-
         pod shape and proportions of segments  more or less dissimilar
         to drawings of Fig. 12C.  Rami of uropod either flat, lance-
         olate and broad or linear and narrow 	 4

4(3)   Mesial process of pleopod 2 scarcely or not present 	 5
      Mesial process of pleopod 2 present and well-developed 	 6

5(4)   Inner and outer basal apophyses of endopod of pleopod 2 distinct
         (Fig. 6B, C);  caudal process usually broadly rounded, cannula
         long and narrow (Figs 6D, E, 14A-M);  shape of endopod and
         proportions of segments as  in Fig. 6B:              A. eommunis
      Inner basal angle of endopod of pleopod 2 obtuse, sharply angled,
         or produced into small, acutely pointed apophysis, outer basal
         apophysis not distinct (Fig. 15C);  caudal process often with
         acutely pointed apex, cannula short and wide (Figs 15D, 16A-
         H);  shape of endopod and proportions  of segments as in Fig.
         15C:                                             A. i-ntermedius

6(4)   Cannula of pleopod 2 long and narrow or triangular 	 7
      Cannula of pleopod 2 relatively short and wide 	 9
                                  20

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Fig, 12.  A. lati-oaudatus.   A, dactylus and propodus of first perae-
opod;  B, first pleopod;  C, second pleopod;  D, E, respectively dor-
sal and ventral surfaces of endopod of second pleopod;  F, uropod;  G,
uropod and telson.  (After Williams, 1970).
can.= cannula.
                                21

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Fig. 13.  A.  latioaudatus.
endopod of second pleopod.
Variation in morphology of tip of
A-F, ventral views.  From Williams  (1970)
Fig. 14.  A. oommun-Ls.  Variation in morphology of tip of endopod
of second pleopod.  A-M, ventral views; A-K, specimens from eastern
States and southeastern Canada;  L, specimen from Washington;  M,
specimen from Colorado.  From Williams (1970).
                                22

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Fig. 15.  A. intermedius.   A, dactylus and propodus of first perae-
opod;  B, first pleopod; C, second pleopod;  D, E, respectively dor-
sal and ventral surfaces of tip of endopod of second pleopod.
(After Williams, 1970).
can.= cannula, c.p.= caudal process, v.g.= ventral groove.
                                 23

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   Fig.  16.   A.  intermedius.   Variation in morphology of tip of endo-
   pod of second pleopod.   A-H,  ventral views.   From Williams (1970).

7(6)  Antenna 2 slightly longer  than body.   Pleopod 1 distinctly
         shorter than pleopod 2, division of distal and proximal
         segments incomplete (Fig.  17B).   Caudal process of pleopod
         2 rounded,  not well-developed (but clearly present), and
         lacking associated hooks and setae;  cannula and subequal
         mesial process extending beyond caudal  process (Fig. 17D,
         E);   shape  of endopod and proportions of segments as in
         Fig. 17C.   Rami of uropod linear,  narrow and subequal in
         length to each other (endopod only slightly longer) (Fig.
         17F):                                               A.  attenuatus
      Antenna 2 usually shorter  than body but sometimes subequal.
         Pleopod 1 subequal in length to or slightly longer than
         pleopod 2,  division between distal and  proximal segments
         more or less complete (Figs 18B, 20A-H, 21B).  Caudal pro-
         cess of pleopod 2 distinctly developed, large, terminating
         in prominent apex, usually with several fine comb-like struc-
         tures on dorsal surface and some lateral  setose  processes;
         cannula and mesial process usually not  extending distally
         beyond caudal process (Figs 18D, E, 19A-J, 21D, E, 22A-F);
         shape of endopod and proportions of segments more or less
         dissimilar  to Fig. 17C.  At least endopod of uropod lanceo-
         late, distinctly longer than exopod (Figs 18F, 21F) 	
         	 A.  racowitzai- 	 8
                                   24

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Fig. 17.  A. attenuatus.  A, dactylus and propodus of first peraeopod;
B, first pleopod;  C, second pleopod;  D, E, respectively dorsal and
ventral surfaces of tip of second pleopod;  F, uropod. (After Williams,
1970).
can.= cannula, m.p.= mesial process, v.g.= ventral groove.
                                 25

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Fig. 18.  A.  raaovitsai raeovitsai.   A, dactylus and propodus of first
peraeopod;  B, first pleopod;   C, second pleopod;   D, E,  respectively
dorsal and ventral surfaces of tip of endopod of second pleopod;  F,
uropod.   (After Williams, 1970).
can.= cannula, c.p.= caudal process,  m.p.= mesial  process,  v.g.= ventral
groove.
                                   26

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8(7)  Distal segment of pleopod 1 more or less subrectangular  (Fig.
         18B).   Cannula of pleopod 2 triangular in shape, not markedly
         thickened on outer margin (Figs 18D, E, 19A-J);  shape of end-
         opod and proportions of segments as in  Fig. 18C. (Table 1):
                                                A.  vacovi-tza-L raoov-itza-i
      Distal segment of pleopod 1 more or less subovate (Fig. 20A-H).
         Cannula of pleopod 2 not conspicuously triangular in shape,
         and outer margin thickened (Figs 21D, E, 22A-F);  shape of
         endopod and proportions of segments as in Fig. 21C.    (Table 1) :
                                                 A.  vaaovitzai australis
  Fig. 19.  A. vacovitzai racovitzai.  Variation in morphology of tip of
  endopod of second pleopod.  A-J, ventral views;  A-H, J, specimens
  from eastern States and southeastern Canada;  I, specimen from Washing-
  ton.  From Williams (1970).
                                     27

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   Fig. 20.  A.  racovitzai racovitzai.   Variation in shape of first
   pleopod.

                                TABLE 1

     SOME DIFFERENCES BETWEEN TWO SUBSPECIES OF ASELLUS RACOVITZAI
                             (males only)
                                           (From Williams 1970, Table 4)

length of antenna 2
body length
Pleopod 2
length of endopod
length of distal segment of exopod
Pleopod 2-distal segment of exopod
length
width
Pleopod 2 -endopod
length
width

Range
M*
± S.D.
Range
M*
+ S.D.
Range
M*
± S.D.
Range
M*
+ S.D.
A. raeovitzai
vaeowitza-i
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. racovitzcci
australi-s
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)
                                  28

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Fig. 21.  A. raoovitzai australis.  A, dactylus and propodus of first
peraeopod;  B, first pleopod;  C, second pleopod;  D, E, respectively
dorsal and ventral surfaces of tip of endopod of second pleopod;  F,
uropod.  (After Williams, 1970).
can.= cannula, c.p.= caudal process, m.p.= mesial process, v.g.=
ventral groove.

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                    Proximal pro-
                   with long stout
                     Mesial process
   Fig. 22.  A.  racovitzai australis.   Variation in morphology of tip
   of endopod of second pleopod.   A-F,  ventral views.   From Williams
   (1970).

9(6)     Antenna 2 usually shorter than  body length.   Proximal pro-
           jection on palm of propodus  of peraeopod 1  typically with
           tooth-like  seta  (Fig. 23A).   Mesial process of pleopod 2
           usually long and not very wide; cannula of moderate width
           (Figs 23D, E, 24A-G);   endopod shape and/or proportions of
           segments as in Figs 23C,  25A-J;  proximal segment of exopod
           frequently with marginal  setae  (Fig. 23C).   Uropods mostly
           subequal in length to telson.   Both telson and uropods only
           moderately  setose  laterally (Fig.  23F, G)  (Table 2):
                                                              A.  fovbesi
        Antenna 2 usually subequal in length to body.
           jection on palm of propodus  of peraeopod 1
           seta  (never a tooth-like  seta)  (Fig.  26),
           of pleopod 2 usually short and wide, cannula very wide with
           recurved outer lip (Figs  27C,  D,  28A-H);   endopod shape and
           proportions of segments as in  Fig.  27B;  proximal segment of
           exopod without marginal setae  (Fig. 27B).   Uropods distinct-
           ly longer than telson and both telson and uropods very
           setose  laterally (Fig. 27E) (Table  2):             A.  obtusus

10(2)    Body of endopod and associated  terminal processes of pleopod
           2 arranged in spiral fashion so that 'ventral1 groove
           actually lies dorsally (Fig.  29C,  D, E);   cannula not
           visible;  endopod shape and  proportions of segments as in
           Fig.  29C.   Endopod of uropod shorter than peduncle (Fig.
           29F) :                                              A.  montanus
        Body of endopod of pleopod 2 not  spirally arranged although
           some torsion may be displayed  by terminal processes (i.e.
           not as indicated in Fig.  29C,  D,  E);  cannula (at least tip)
           visible from ventral or dorsal view;  endopod shape and
           proportions of segments more or less dissimilar to Fig.
           29C.   Endopod of uropod typically longer than or subequal
           in length to peduncle 	 11
30

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                                                                 m. p.
                                                                    v.g.
Fig. 23.  A. forbesi.  A, dactylus and propodus of first peraeopod;
B, first pleopod;  C, second pleopod;  D, E, respectively dorsal and
ventral surface of tip of endopod of second pleopod;  F, uropod;  G,
uropod and telson.   (After Williams, 1970).
can.= cannula, c.p.= caudal process, m.p.= mesial process, v.g.=
ventral groove.
                                  31

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Fig. 24.  A. forbesi.   Variation in morphology of tip of endopod
of second pleopod.  A-H, ventral views.  From Williams (1970).
Fig. 25.  A. forbesi.   Variation in shape of endopod of second
pleopod.  From Williams (1970).
Fig. 26.  A.  obtusus.  Distal segments
of first peraeopod with dactylus and
palm of propodus shown in greater de-
tail.  From Williams (1970).
                                32

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Fig. 27.  A. obtusus.  A, first pleopod;  B, second pleopod;  C, D,
respectively dorsal and ventral surfaces of endopod of second pleopod;
E, uropod and telson.  (After Williams, 1970).
can.= cannula, c.p.= caudal process, m.p.= mesial process, v.g.=
ventral groove.
                                 33

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   Fig. 28.  A.  obtusus.   Variation in morphology of tip of endopod
   of second pleopod.  A-H, ventral views.  From Williams (1970).

                                TABLE 2

      SOME DIFFERENCES BETWEEN TWO SPECIES OF ASELLUS (males only)
                                           (From Williams 1970, Table 5)

Maximum body length (mm)
length of antenna 2
body length
Pleopod 2-proximal segment
Number of marginal setae
Pleopod 2-endopod
length
width
uropod length
telson length


Range
M*
+ S.D.
of exopod
Range
M*
± S.D.
Range
M*
+ S.D.
A. forbesi-
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
A. obtusus
12.5
0.8-1.5
1.03
0.19
0
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)
                                   34

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Fig. 29.  A. montanus;  A, dactylus and propodus of first peraeopod;
B, first pleopod;  C, second pleopod; D, E, respectively dorsal and
ventral surfaces of tip of endopod of second pleopod;  F, uropod.
(After Williams, 1970).
'v.g.'= 'ventral* groove.
                                 35

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Fig. 30.  A.  nodulus.   A, dactylus and palm of first peraeopod;   B,
first peraeopod;   C, first pleopod;  D, second pleopod;   E,  F, respec-
tively dorsal and ventral surfaces of tip of endopod of second pleopod;
G, uropod;  H,  uropod and telson.   (After Williams,  1970).
'd.p.'= dorsal  process, 'v.p.'= ventral process.
                                 36

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11(10)  Cannula of pleopod 2 completely enclosed between two promin-
           ent, heavily sclerotized, non-dentate, broadly rounded
           'ventral'and 'dorsal' processes (Fig. 30E, F);  distal end
           of endopod with small degree of torsion so that 'ventral'
           groove lies laterally;  endopod shape and proportions of
           segments as in Fig. 30D.  Endopod of uropod distinctly
           longer than peduncle (Fig. 30G, H):                 A. nodulus
        Cannula of pleopod 2 not enclosed between two processes as des-
           cribed above (i.e. not as indicated in Fig. 30E, F);   dis-
           tal end of endopod not displaying any obvious sign of
           torsion;  ventral groove distinct;  endopod shape and pro-
           portions of segments more or less dissimilar to drawing
           of Fig. 30D.  Endopod of uropod typically only slightly
           longer than or subequal in length to peduncle 	 12

12(11)  Cannula of pleopod 2 visible from ventral view, lateral  pro-
           cess not (or only slightly) developed, mesial process prom-
           inent and bifid, caudal process wide and irregularly dentate
           (Fig. 31D, E);  endopod shape and proportions of segments
           as in Fig. 31C:                              A,  dentadaetylus
        Cannula of pleopod 2 often hidden by lateral process in ventral
           view, lateral process well-developed, mesial process  prom-
           inent but with either rounded or dentate distal margin (not
           bifid), caudal process absent or rounded (not dentate);
           endopod shape and proportions of segments more or less dis-
           similar to Fig. 31C 	 13

13(12)  Caudal process of pleopod 2 absent, distal dorsal surface of
           endopod with numerous minute setae,  lateral process  non-
           sclerotized with rounded margin, mesial process obtusely
           dentate (Fig. 32C, D);  endopod shape and proportions of
           segments with some variation but typically as shown in
           Figs 32B, 33A-G.  Uropods about half as long as telson
           (always<0.7), peduncle about as wide as long (Fig. 32E):
                                                A.  brewioauda brevioauda
           [Pending a further examination of specimens, two subspecies
           of A. bTevioauda have tentatively been proposed by Williams
           (1970), A.  bvevi.cau.da brevieauda Forbes, 1876, and A. brevi-
           occuda bivittatus Walker- 1961.   The differences between them
           are small and mainly involve slight differences in setation,
           segment proportions, and number of segments in antennal fla-
           gella.  Table 3 details the principal differences.]
        Distal endopodial processes of pleopod 2 (considered as  a
           whole) of shape and arrangement other than as described
           for A. bvevioauda bveviaauda, distal dorsal surface of
           endopod lacks minute  setae;   endopod shape and proportions
           of segments more or less dissimilar to drawings of Figs
           32B, 33A-G.  Uropods subequal to or slightly longer than
           telson, peduncle always longer than wide	 14
                                    37

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Fig. 31.  A. dentadaotylus.   A, dactylus and propodus of first perae-
opod;  B, first pleopod;  C, second pleopod;  D,  E, respectively dor-
sal and ventral surfaces of tip of endopod of second pleopod;  F,
uropod.  (After Williams, 1970).
can.= cannula, c.p.= caudal process, m.p.= mesial process, v.g.=
ventral groove.
                                 38

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 Fig. 32.  A. brewicauda brevieauda.  A, first pleopod;  B, second
 pleopod;  C, D, respectively dorsal and ventral surfaces of tip of
 endopod of  second pleopod;  E, uropod.  (After Williams, 1970).
 can.= cannula,  l.p.=  lateral process, m.p.= mesial process, v.g.=
 ventral groove.

14(13)   Cannula of pleopod 2 small and narrow,  lateral process  pointed,
           mesial process obtusely dentate,  caudal  process  absent  (Figs
           34D,  E,  35A-G);   endopod shape and proportions of segments
           as in Fig.  34C:                                A.  serupulosus
        Cannula of pleopod 2 not small  and  narrow,  lateral  process
           rounded,  mesial process not  dentate (but with rugose pos-
           terior lobe), caudal  process present,  broadly rounded with
           some rugosities (Fig.  36D,  E);   endopod  shape and propor-
           tions of segments as  in Fig.  36C:                     A.  keriki.
                                    39

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Fig. 33.  A.  brevicauda brevicauda.   Variation in shape and pro-
portions of segments of second pleopod.   From Williams (1970).
                             TABLE 3

PRINCIPAL DIFFERENCES BETWEEN TWO SUBSPECIES OF ASELLUS BEEVICAUDA
                          (males only)
                                        (From Williams 1970, Table 3)

                                       A.  brevioauda   A.  brevioauda
                                          brewioauda      bivittatus

Antenna 1
Antenna 2
Peraeopod 1
Pleopod 1
Pleopod 2

Maximum body length (mm)
No. segments in flagellum
No. segments in flagellum
No. teeth-like setae on
dactylus
Triangular process near mid-
point of palm of propodus
No. coupling hooks on sympod
width
length 6
No. plumose setae on distal
segment

width "^P°d
No. plumose setae on distal
segment of exopod
uropod length
telson length
17.0
11-17
60-124
6-14
present
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 ^6 0 4.4

                               40

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Fig. 34.  A. serupulosus.  A, dactylus and propodus of first peraeopod;
B, first pleopod; C, second pleopod; D, E, respectively dorsal and ven-
tral surfaces of tip of endopod of second pleopod;  F, uropod.  (After
Williams, 1970).
can.= cannula, l.p.= lateral process, m.p.= mesial process, v.g.=
ventral groove.
Fig. 35.  A. sorupulosus.   Variation in morphology of endopod tip of
second pleopod.  A-C, E, G, ventral views;  D, F, dorsal views.
From Williams  (1970).
                                  41

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Fig. 36.  A.,  kenki.   A, first pleopod;  B, distal margin of first
pleopod;  C,  second left pleopod;  D, E, respectively dorsal and ventral
surfaces of tip of endopod of second left pleopod.  (After Bowman, 1967)
can.= cannula, c.p.= caudal process, l.p.= lateral process, m.p.= mesial
process, v.g,= ventral groove.

                                 42

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                                SECTION V

                               REFERENCES

Bartsch, A. F. 1948.  Biological aspects of stream pollution.  Sewage
     Works Journal, 20:292-302.
Bartsch, A. F. and W. M. Ingram, 1959.  Stream life and the pollution
     environment.  Public Works, 90:104-110.
Birstein, Ya. A. 1951.  Freshwater Isopods (Asellota). Fauna S.S.S.R.,
     7(5), 148pp.[English translation by Israel Program for Scientific
     Translations, 1964]
Bowman, T. E. 1967.  Asellus kenki, a new isopod crustacean from springs
     in the eastern United States.  Proceedings of the Biological
     Society of Washington, 80:131-140.  [A.  kenki described]
Clifford, H. F. 1966.  The ecology of invertebrates in an intermittent
     stream.  Investigations of Indiana Lakes and Streams, 7(2):57-98.
Cole, G. A. and W. L. Minckley, 1968.  A new species of aquatic isopod
     crustacean (genus Asellus] from the Pueblo plateau, central
     Mexico.  Proceedings of the Biological Society of Washington, 81:
     775-60.
Ellis, R. J. 1961.  A life-history study of Asellus intermedius Forbes.
     Transactions of the Americari Microscopical Society, 80(1) : 80-102.
	 1971.  Notes on the biology of the isopod Asellus tomalensis
     Harford in an intermittent pond.  Transactions of the American
     Microscopical Society, 90(1):51-61. [synonym of A.  occidentalis
     Williams, 1970]
Forbes, S. A. 1876.  List of Illinois Crustacea, with descriptions of
     new species.  Bulletin of the Illinois Museum of Natural History,
     1:3-25.  [A. brevicauda brevicauda and A. intermedius described]
Carman, S. 1889.  Cave animals from southwestern Missouri.  Bulletin of
     the Museum of Comparative Zoology at Harvard University, 17(6):225-
     39.   [L. hoppinae hoppinae described by Faxon]
Harger, 0. 1876.  Description of Mancasellus brachyurus, a new fresh-
     water isopod.  American Journal of Science and Arts, 11(3):304-5.
     [L. brachyurus described]
Henry, J. -P. and G. Magniez, 1968.  Sur la systematique et la biogeo-
     graphique des Asellides.  Comptes rendus des seances de I'Academie
     des Sciences, Paris,  267:87-9.
	 1970.  Contribution a la systematique des Asellides (Crustacea
     Isopoda).  Annales de Speleologie, 25(2):335-67.
Hubricht, L. and J. G. Mackin, 1949.  The freshwater isopods of the
     genus Lirceus (Asellota, Asellidae).  American Midland Naturalist,
     42(2):334-49.  [L. hargeri, L. alabamae, L. richardsonae,
     L. megapodus, L. hoppinae ozarkensis, L. bidentatus, L* bicuspida-
     tus, L. garmani, L. trilobus described]
Hynes, H. B. N. 1960.  "The biology of Polluted Waters."  Liverpool Uni-
     versity Press, Liverpool, 202 pp.
Kolkwitz, R. and M. Marsson, 1909. Okologie der tierische Saprobien.
     Beitrage zur Lehre von der biologische Gewasserbeurteilung.
     Internationale Revue der gesampten Hydrobiologie und Hydrographie,
     2:126-152.
                                   43

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Mackin, J. G. and L. Hubricht, 1938.  Records of distribution of species
     of isopods in central and southern United States, with descriptions
     of four new species of Manoasellus and Asellus (Asellota, Asellidae).
     American Midland Naturalist, 19:628-37.  [A. dentadactylus, A. mon-
     tanus, L. louisianae, L.  hoppinae ouachitaensis described]
Racovitza, E. G. 1920.  VII.   Notes sur les isopodes.  6,  Asellus
     communis Say.  7,  Les pleopodes I and II des^Asellides;  Morpholo-
     gic et development.  Archives de Zoologie experimental et generale.
     Notes et Revue, 58:79-115.
Rafinesque, C. S. 1820.  Annual synopsis of new genera and species of
     animals, plants etc. discovered in North America.  Annals of Nature,
     1:1-16.  [L. fontinalis described]
Richardson, H. 1900.  Synopses of North American invertebrates. VIII. The
     Isopoda. Part II.  American Naturalist, 34:295-309.
	 1901.  Key to the isopods of the Atlantic coast of North America
     with descriptions of new and little known species.  Proceedings of
     the United States National Museum, 23:494-579.  [A. attenuatus
     described]
Say, T. 1818.  An account of the Crustacea of the United States.  Journal
     of the Academy of Natural Sciences of Philadelphia, 1:374-401, 423-33.
     [A. communis, L.  lineatus described]
Seidenberg, A. J. 1969.  Studies on the biology of four species of fresh-
     water isopods (Crustacea, Isopoda, Asellidae) in east-central Illin-
     ois. Ph. D. dissertation, University of Illinois.
Styron, C. E. 1968.  Ecology of two populations of an aquatic isopod,
     Lirceus fontinalis Raf., Ecology,  49:629-36.
	 1969.  Taxonomy of two populations of an aquatic isopod, Lirceus
     fontinalis  Raf.,  American Midland Naturalist, 82:402-16.
Walker, B. A. 1961.  Studies  on Doe Run, Meade County, Kentucky, IV.   A
     new species of isopod crustacean (genus Asellus}  from Kentucky.
     Transactions of the American Microscopical Society, 80:385-90. [A.
     brevicauda  bivittatus described]
Williams, W. D.  1970.   A revision of North American epigean species of
     Asellus (Crustacea:Isopoda).  Smithsonian Contributions to Zoology,
     49:1-80.  [A.  racovitzai racovitzai,  A. racovitzai australis, A.
     forbesi, A.  obtusus, A.  laticaudatus,  A.  scrupulosus, A. nodulus,
     A. occidentalis described]
                                   44

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                                 SECTION  VI

                          INDEX  OF  SCIENTIFIC  NAMES

alabamae  (Liroeus) 3  14                garmani  (Liroeus) 3  14
aquations  (Asellus) 3  2                hargeri  (Liroeus) 3  14
Asellidae, 1                          hoppinae hoppinae  (Liroeus )3  14
Asellopsis3 1                         _ ouaohitaensis  (Liroeus) 3  14
Asellus,  1,2,3,4,7,11,13,17           _ ozarkensis  (Liroeus), 14
_ aquatiaus,  2                      intermedius  (Asellus),  13,20,23,24
_ attenuatus, 13,24,25              kenki  (Asellus),  13,40,42
_ brevioauda  bivittatus,  13,37,40   latioaudatus  (Asellus) 3  13,20,21,22
__ brevioauda,  13,37,39,40      lineatus (Liroeus),  14
_ oommunis, 4,5,6,7,8,9,10,13,20,   Liroeus3  1,2,3,4,14,17
    22                                _ alabamae,  14
_ dentadaetylus 3 13,37,38           _ biauspidatus ^  14
_ forbes-i,  13,30,31,32              _ bidentatus3 14
_ -inteYmedius , 13,20,23,24          _ braehyurus, 14
_ kenki-j 13,40,42                   _ fontinalis, 14
_ lat-i-caudatus j 13,20,21,22         _ garman-i,  14
_ montanuSj 13,30,35                _ hargeri^  14
_ noduluSj  13,36,37                _ hoppinae hoppinae 3  14
_ obtusus3  14,30,32,33,34           __ ouaehitaensis 3  14
_ oooidentalis 3 14,18,19,20         __ ozarkensis3  14
_ racovitzai  australis3  14,27,28,   _ lineatus 3  14
    29,30                            _ 1ouisianae3 15
__ racovitzai3  14,26,27,28      _ megapodus3  15
                j 14,40                _ richardsonae 3  15
_                                  _
attenuatus  (Asellus) 3  13,24,25       _ trilobus,  15
bicuspidatus  (Livoeus) 3  14           louisianae (Liroeus) ,15
bidentatus  (Liroeus )3  14            Manoasellus3  1
Bopyridae,  1                         megapodus  (Liroeus )3  15
braohyuvus  (Liroeus )3  14            montanus  (Asellus) 3  13,30,35
brevioauda  bivittatus  (Asellus)3  13, nodulus  (Asellus)3  13,36,37
    37,40                            obtusus  (Asellus) 3  14,30,32,33,34
_ brevioauda  (Asellus), 13,37,39,  oooidentalis  (Asellus) 3 14,18,19,20
    40                               Pseudobaioalasellus 3  1
Caeoidotea3 1                        raoovitzai australis (Asellus),,  13,
Cirolanidae,  1                            27,28,29,30
oommunis  (Asellus) 3 4,5,6,7,8,9,10,  _ raoovitzai (Asellus) 3  13,26,27,
    13,20,22                              28
Conasellus3 1                        richardsonae  ( Liroeus )3 15
dentadaotylus  (Asellus),  13,37,38   sorupulosus (Asellus) 3  14,40,41
fontinalis  (Liroeus) 3  14            Sphaeromatidae, 1
forbesi  (Asellus), 13,30,31,32       Sphaeromidae ,  1
                                     trilobus  (Liroeus) 3  15
                                     45

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  SELECTED WATER
  RESOURCES ABSTRACTS
  INPUT TRANSACTION FORM
                      I. Report Wo.
                         3. Accession No.
                         w
  4.  Title  BIOTA  OF FRESHWATER ECOSYSTEMS   IDENTIFICATION MANUAL   5.  Report Date
     NO.  7.  Freshwater Isopods (Asellidae)  of North America,     6
  9.  Organization Monash University,
                Clayton, Victoria,
                Australia
  12. Sponsoring Of sanitation

  IS. Supplementary Notes
                                                                      8.  Performing Organization
                                                                         Report No.

                                                                      10.  P
                                           11. Contract/Grant No.
                                                 14-12-894

                                          '13'. Type of Report and
                                              Period Covered
  16. Abstract    A key is given to- the North American genera (Asellus  and Liroeus')  of
               asellid isopods.   Another  key is provided for the surface-living species
               of Asellus but lack of clear, published morphological distinctions in
               the genus Liroeus prevents the construction of a key  for that genus.
               Notes on ecology, collection, preservation and identification are  also
               included.
  17 a. Descriptors
                *Aquatic fauna,  *Isopods,  Distribution,  Preservation,
  17b.identifiers   *Identification Manual,  illustrated key, *Asellidae,  *North America,
                Species List,  Collection,
  lJc.CO WRR Field A Group j QA
  18. Availability
19. Security Class.
   (Report)

20. Security Class.
   (Page)
21. No. of
   Pages

22. Price
                                                          Send To:
                                                          WATER RESOURCES SCIENTIFIC INFORMATION CENTER
                                                          U.S. DEPARTMENT OF THE INTERIOR
                                                          WASHINGTON, D. C. ?Q2<»Q
  Abstractor *•  D-  Williams
             {institution Monash University, Victoria,  Australia.
WRSIC 102 (REV. JUNE 1971)
                                                           4 U. S. GOVERNMENT PRINTING OFFICE : 1672 O - 468-267

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