WATER POLLUTION CONTROL RESEARCH SERES 180BO ELDO4/72
ESHWATER
ECOSYSTEMS
Identification
Manual
THE FRESHWATER
AMPHIPOD CRUSTACEAN:
(GAMMARIDA
OF NORTH
AMERICA
U.S. ENVIRONMENTAL PROTECTION AGENCY
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Biota of Freshwater Ecosystems
Identification Manual No. 5
THE FRESHWATER AMPHIPOD CRUSTACEANS (GAMMARIDAE) OF NORTH AMERICA
by
John R. Holsinger
Department of Biology,
Old Dominion University
Norfolk, Virginia 23508
for the
ENVIRONMENTAL PROTECTION AGENCY
Project # 18050 'ELD
Contract # 14-12-894
April 1972
For'sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402 - Price $2.75
Stoc'k Number 5501-0369
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EPA Review Notice
This report has been reviewed by the Environmen-
tal Protection Agency and approved for publication.
Approval does not signify that the contents nec-
essarily reflect the views and policies of the EPA,
nor does mention of trade names or commercial pro-
ducts constitute endorsement or recommendation for
use.
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11
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FOREWORD
'/The Freshwater Amphipod Crustaceans (Ganunaridae) of North
America" is the.fifth 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 Environ-
mental 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
limited to, freshwater representatives of the following
groups: branchiuran crustaceans (Argulus}, isopod crusta-
ceans (Asellidae), decapod crayfish crustaceans (Astacidae),
leeches (Hirudinea), polychaete worms (Polychaeta), fresh-
water planarians (Turbellaria), aquatic dryopoid beetles
(Dryopoidea) and freshwater clams (Sphaeriacea).
ill
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ABSTRACT
The amphipod crustacean family Gammaridae is represented in the fresh-
waters of North America by eight genera and 81 described species;
numerous other species are still undescribed. These eight genera,
with the number of described North American freshwater species in
parentheses, include: Gammarus (9), Crangonyx (18), Synurella
(4), Apoorangonyx (6), Stygoneetes (29), Stygobromus (10), Baatrurus
(3), and Alloorangonyx (2). Ecologically, the freshwater gammarids
are an important group of aquatic invertebrates, with species found in
a variety of biotopes, including lakes, streams, ponds, swamps, springs,
and subterranean waters.
The identification of amphipods is rather difficult, especially because
accurate determinations often depend on the recognition of diagnostic
character combinations and the study of the whole morphology of the
animals. In order to facilitate the identification of genera and the
determination of species, analytical keys with accompanying illustrations
are presented. Of further assistance are the inclusion of distributional
maps showing the ranges of many of the species. A brief synopsis of
pertinent ecological information and the type locality for each species
are also given.
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CONTENTS
Section Page
I Introduction 1
Ecology 3
Collecting and Preservation 5
Identification 6
Morphology 7
II Family Gammaridae 11
Key to Genera of the Family Gammaridae in North America 13
Gammca>us Group 17
Genus Gammarus 17
Key to the North American Species of Gammarus 19
Annotated List of the Species 21
CTangonyx Group 28
Genus Crangonyx 28
Key to the North American Species of CTangonyx 28
Annotated List of the species 33
Genus SynuTella 48
Key to the North American Species of Symcrella 48
Annotated List of the Species 48
Genus Apoorangonyx 53
Key to the Species of Apoovangonyx 53
Annotated List of the Species 54
Genus Stygoneotes 55
Key to the Species Groups of Stygoneotes 55
Annotated List of the Species 59
Genus Stygobrorms 65
Key to the North American Species of Stygobromus 65
Annotated List of the Species 68
Genus Baotrurus 73
Key to the Species of Bactpurus 73
Annotated List of the Species 73
Alloorangonyx Group 77
Genus Allocrangonyx 77
Key to the Species of Alloarangonyx 77
Annotated List of the Species 77
III Acknowledgments 79
IV References 81
V Glossary 85
VI Index of Scientific Names 87
vi-i
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FIGURES
1 Generalized
2 Structure of
3 Structure of
4 Structure of
5 Structure of
6 Structure of
7 Structure of
8 Distribution
9 Distribution
10 Distribution
11 Structure of
12 Structure of
13 Distribution
14 Distribution
15 Distribution
16 Distribution
17 Distribution
18 Distribution
19 Distribution
20 Distribution
21 Structure of
22 Distribution
23 Structure of
24 Structure of
25 Structure of
26 Structure of
27 Distribution
28 Distribution
29 Distribution
30 Structure of
31 Distribution
32 Structure of
freshwater gammarid amphipod
freshwater Gammaridae
freshwater Gammaridae
freshwater Gammaridae
freshwater Gammaridae
Gammarus
Gammarus
of species of Garmarus in North America
of species of Gammarus in North America
of species of Gammarus in North America
Crangonyx
Crangonyx
of species of Crangonyx in North America
of species of Crangonyx in North America
of species of Crangonyx in North America
of species of Crangonyx in North America
of species of Crangonyx in North America
of species of Crangonyx in North America
of species of Crangonyx in North America
of species of Crangonyx in North America
Synurella
of species of Synurella in North America
Apoorangonyx
Stygonectes
Stygonectes
Stygobromus
of species of Stygobromus in North America
of species of Stygobromus in North America
of species of Stygobromus in North America
Bactrurus
of species of Baetrurus in North America
AIlocrangonyx
Page
7
10
12
14
16
18
20
22
24
26
29
32
35
37
38
39
40
42
45
47
49
50
52
56
58
66
69
70
72
74
76
78
Vlll
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SECTION I
INTRODUCTION
The major purpose of this manual is to assist in the recognition and
determination of the freshwater species of amphipod crustaceans of the
family Gammaridae in North America north of Mexico and to provide some
useful information on their distribution and ecology. Amphipods
belong to the order Amphipoda of the class Crustacea. Amphipoda is
further classified in the superorder Peracarida of the subclass
Malacostraca and is subdivided into four suborders consisting of
Gammaridea, Hyperiidea, Caprellidea, and Ingolfiellidea. The family
Gammaridae is one of about 57 families contained within the suborder
Gammaridea (see Barnard, 1958, for a list of the families). Caprellidea
and Hyperiidea are exclusively marine groups while Gammaridea and
Ingolfiellidea have representatives in freshwater. Ingolfiellids are
unknown from North America, however, thus only the gammarideans are
represented in the freshwater environment of the continent.
Amphipod crustaceans are one of the largest and most prominent groups
of freshwater invertebrates. Five families, including Corophiidae,
Haustoriidae, Hyalellidae (superfamily Talitroidea), Pontogeneiidae, and
Gammaridae, are represented in the freshwaters of North America. The
first four families are represented by only four genera and five species,
however, and only two of these species (Hyalella azteea and Pontoporeia
affi-nis] are strictly freshwater forms. In contrast, Gammaridae is
represented by nine genera and numerous species; seven genera are ex-
clusively freshwater and five of these are known only from subterranean
habitats (Holsinger, 1967). The other two genera, Gammcacus and
AnisogammaruSj occur in marine, brackish, and fresh waters, but
Anisogammarus is found in freshwater only on a marginal basis (three
species along the Pacific coast) and is primarily a brackish and marine
group. Eight genera, including Gccmmaxus, CrangonyXj Synurellaj
ApocrangonyXj Stygoneotes3 Stygot>romus3 Bao-trurus, and Alloopangonyxf are
considered in this manual.
Prior to the papers of Hubricht and Mackin (1940), Hubricht (1943), and
Shoemaker (1940, 1942a, 1942b), very little detailed information was
available on the freshwater amphipod fauna of North America. In compari-
son with Europe, where papers on freshwater amphipods have been published
steadily since the 1800's, the extent and distribution of the North
American fauna was very poorly known. Although a few significant papers
on the group were published around the turn of the century (late 1800's
and early 1900's) and in the 1930's, it wasn't until the 1940's that a
concerted effort to describe the freshwater fauna was initiated. Since
1940, approximately 25 major taxonomic papers have been published, six of
them as recently as 1970-71. References to most of the pertinent liter-
ature dealing with the group are found in the bibliography of this manual
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Currently, thanks largely to the proliferation of taxonomic and ecologi-
cal studies in recent years, 81 valid freshwater species of Gammaridae
are now described and at least 100 more are recognized but as yet
undescribed. Descriptions of many of the undescribed forms are at the
moment in various stages of preparation (see remarks throughout this
manual). Within this taxonomic framework, it was possible to prepare
what are hoped to be reliable analytical keys to the eight genera and
most of the described species. Since the group is still imperfectly
known and new data are rapidly accumulating on taxonomy, distribution,
and ecology, the writer actively solicits comments and criticisms from
workers in the field on the utility of these keys. Refinements can
undoubtedly be made, especially after the keys are put to the test of
active use. Revisions, incorporating both corrections and new infor-
mation, will certainly be needed in the not too distant future.
With the exception of Stygonectes, keys to individual species in each
genus are included. A key to the species groups of Stygoneotes was
prepared but a key to the individual species was not. Following the
keys are annotated lists incorporating pertinent information of the
geographic distribution and ecology of each species. Also included are
range maps of all but three species of Garmavus, CTangonyx, Syniupella,
Stygobromus, and Baetma>us. Since maps showing the distribution of
species of ApooTangonyx, Allocvangonyx, and Stygonectes were recently
published (Holsinger, 1967, 1969a, 1969b, 1971), they were not repeated
here.
The keys and annotated lists are based both on the taxonomic literature
and the writer's examination of material. Leading up to the preparation
of this manual, approximately 2700 collections of amphipods were exam-
ined. Whenever possible, data relative to ecology were also compiled
and analyzed. While some of the distributional information is based on
the published literature, a significant percentage of it is being pub-
lished here for the first time. Species ranges on the distribution maps
are shown by continuous shading where locality records were more or less
geographically contiguous. Where large gaps or disjunctions occurred in
the ranges, they are so noted.
The continuous collecting and study of freshwater amphipods will doubt-
less result in the extension of many of the plotted ranges. In some
instances, however, a more critical examination and statistical evalu-
ation of some of the species will lead to considerable refinement and
closer circumscription of other ranges. Clearly, as shown in the
annotated lists, a great deal remains to be learned about the ecology
and other aspects of the biology of the species concerned. This is espe-
cially true of the subterranean forms, where detailed information is
presently available on the life history of only two or three species.
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ECOLOGY
Very general notes on the ecology of each species are included in the
annotated lists, therefore only a broad summary is necessary at this
point. Freshwater amphipods occupy numerous niches within the realm
of the aquatic environment. Although many observations are available
on the broader adaptive zones filled by these animals, very little is
known about species interactions, community roles, and niche sepa-
ration. Recent studies by Culver (1970, 1971) on the relationship of
amphipod species in the cave stream communities of southern West Vir-
ginia, however, are rapidly adding to our knowledge of this long
neglected field. Similar studies have been made by Hynes (1955) on
some British gammarids and by Clemens (1950) and Minckley and Cole
(1963) on various species of Gconmarus.
A number of works contain general discussions on the ecology of fresh-
water Gammaridae. A few of the recent papers treating the broader
aspects of this subject are those by Pennak (1953), Bousfield (1958),
and Holsinger (1967, 1969a). The European species have been treated
more thoroughly and in greater detail (see for instance Ginet, 1960a,
1960b). In general, freshwater gammarids are cold-stenothermal,
photonegative, and thigmotactic. The majority of species are found in
smaller bodies of water. Few species inhabit large rivers or the open
water of larger lakes; most species are associated with the substrate
in one or another. Amphipods are often abundant in small streams,
sloughs, swamps, ditches, ponds (temporary and permanent), drains,
seeps, springs, and cave streams and pools. The greatest number of
species (ca. 65-70 percent of the total North American amphipod fauna)
inhabit subterranean habitats, where many forms have been described
from caves, wells, seeps, outlets of drains, and sometimes springs.
Undoubtedly the interstitial environment, which is still poorly known
in North America outside of what has been learned mostly through the
indirect investigations of biospeleologists, contains numerous species
that have yet to be discovered.
Many of the cavernicolous species are not restricted to caves per se
but are also found in other nearby groundwater habitats such as wells
and seeps. Moreover, dispersal through the interstitial medium between
caves is strongly indicated by the distributional patterns of many
cavernicolous species (Holsinger, 1967, 1969a). Not all subterranean
species are restricted to cave and karst areas but some are found ex-
clusively in groundwater seeps, wells, drains, etc. outside of such
areas. While showing the same morphological specializations as true
cave forms (i.e., loss of eyes and pigment and sometimes attenuation
of appendages), these species are, strictly speaking, phreatobites
and not troglobites. Since some species are found in caves as well as
related goundwater habitats, these ecological categories overlap to
some extent and are often correctly used interchangeably. While many
species are troglobites and/or phreatobites, other species, such as
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Gammams minus, G, troglophilusj Cvangonyx flom-danus and C. forbesi,
occur in caves with regularity but are also as common in springs and
show very little morphological change from one biotope to another.
Aside from morphological differences that are apparently closely
correlated with different adaptive zones, there are striking differ-
ences in the reproductive biology and population control among species
adapted to different biotopes. Many of the species which occupy surface
ponds, swamps, sloughs, and ditches, such as species of Synurella and
Crangonyx in particular, have abbreviated life spans of about one year,
produce large numbers of small eggs, and have sharp seasonal reproductive
peaks. In contrast, the subterranean and cold-water spring forms have
longer life spans (especially the cave species), produce fewer and larger
eggs, and either breed continuously at a very gradual rate or do not have
sharp seasonal reproductive peaks.
The abundance of amphipods in a given habitat is quite variable. With
some notable exception, the subterranean habitats are characterized by
having very sparse faunas, while in contrast, certain epigean habitats
(especially ponds, ditches, sloughs, and swamps in the spring of the year)
may often contain tremendous numbers of animals. Even spring and spring-
run populations are sometimes quite large. Garmarus minus, for example,
is sometimes represented by thousands of animals per square meter in
springs. In aquatic habitats in general, amphipods are usually found
under gravels, dead leaves, grass, and other kinds of debris, or in
masses of vegetation.
In mud-bottomed cave pools, amphipods are often observed "walking" or
scuttling along on the bottom substrate. A number of the cave pool
species have been observed to burrow into the mud or clay substrate,
sometimes spending considerable time beneath the surface. In addition
to receiving nutrients from the clay, these animals are apparently able
to survive periods of drought by migrating deep within their burrows
below the zone of saturation (Ginet, 1960a; Holsinger, unpublished data).
Although observations are rare for this kind of behavior in epigean
species, a similar means of survival is almost certainly used by those
forms which inhabit temporary ponds that dry up during the summer months.
Much of the other information available on freshwater amphipod ecology,
such as coloration, feeding, mating behavior, and development, has been
usefully summarized by Pennak (1953) and will not be repeated here.
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COLLECTING AND PRESERVATION
The collecting of freshwater amphipods is relatively simple but varies
somewhat from one kind of biotope to another. For species which occur
in streams, lakes and larger bodies of water, a fine-meshed dipnet is
useful, especially if swept through masses of aquatic vegetation or
debris. For quantitative sampling, the Surber bottom sampler for
streams and the Ekman dredge for lakes or ponds are recommended.
In small bodies of water, amphipods can usually be removed directly
from the substrate, particles of debris or aquatic vegetation by
forceps or small art brushes (camel's-hair brush). These animals can
also sometimes be removed from masses of vegetation by rinsing or
shaking over a container. Where amphipods are found swimming or
walking in the open on the bottom of pools, they can be sucked up into
a syringe, then passed into a tea strainer (fine mesh) and finally re-
moved to a container with a small brush. Procedures for collecting
subterranean amphipods were described in some detail by the writer in
a recent paper (Holsinger. 1967).
Amphipods as well as most other small crustaceans are best preserved
in 70 to 75 percent ethyl alcohol. Commercial rubbing alcohol (either
ethyl or isopropyl) can be used in emergencies but is not recommended
for permanent storage. Amphipods can be stored indefinitely in 70
percent ethyl alcohol, although crowding should be avoided. Because
the integumentary pigments of amphipods are based on various carotenoid-
protein complexes, even the most darkly pigmented specimens lose most
of their coloration after a short time in alcohol. Therefore, if
color patterns are important for identification, they should be recorded
while the animals are still alive or immediately after preservation.
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IDENTIFICATION
The problems inherent in the specific determination of gammarid amphi-
pods have been emphasized by Bousfield (1958), Holsinger (1967). and
Cole (1970a). The major difficulties with making accurate identifi-
cations are the: (a) lack of systematic significance associated with
the genitalia, (b) variation between size classes and successive
instars, (c) pronounced sexual dimorphism in some species, (d) vari-
ation in size and proportion of a number of taxonomically important
characters in older animals, and (e) overlapping ecology and geographic
distribution of many species.
In contrast to some groups of crustaceans, where reliance on only a few
morphological characters is necessary for the separation of closely
related species, taxonomic discrimination of amphipod species frequent-
ly demands that much of the "whole morphology" of the animals be
considered. Diagnostic character combinations are also useful, if not
mandatory, in many instances. One of the most reliable means of sepa-
rating morphologically closely related species is the use of the
"yardstick of difference" derived from a knowledge of morphological
differences between closely related sympatric or syntopic species.
For routine identification to generic level and often to specific
level, specimens can be studied under a dissecting microscope without
previous preparation of material. Watch glasses with black dissecting
wax on the bottoms, small brushes, watchmaker's forceps, and fine
needles are necessary for manipulation and dissection of amphipods.
For more refined study and often for the positive determination of
species, the preparation of slide-mounted appendages and other external
body parts is required. Temporary slide mounts can be made with glycer-
in. The advantage of using this method is that it allows the
investigator a great deal of flexibility in manipulating appendages for
observation in different planes. The disadvantage is that small append-
ages must be returned to a microvial for permanent storage and then re-
moved and remounted for further study. The risk of losing one or more
of these critical structures is compounded by each subsequent exami-
nation. Permanent slide mounts can be made with one of several
commercially available mounting media, such as Hoyers, "Turtox GMC-10",
and glycerin jelly. This method has the disadvantage of limiting
flexibility of manipulation, but it has the advantage of bringing
together in one place a permanent assemblage of appendages for continued
reference. The adoption of a satisfactory method, however, should be
left to the individual investigator, who, after some trial and error,
will arrive at a technique that best suits his purpose. Further refer-
erence to equipment, techniques, and procedures which have been satisfac-
torily used in the study of amphipods and related crustacean groups are
found in Pennak (1953) and Holsinger (1967).
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MORPHOLOGY
The illustration of a representative gammarid araphipod shown in Figure
1 has been prepared to facilitate the recognition of diagnostic
morphological structures. The use of the keys will be made much
easier if the reader is familiar with external morphology. Although
many of the important morphological differences between genera and
species have been illustrated piecemeal at different places in the
keys, the necessity of having the proper perspective of how the "pieces"
fit into the makeup of the whole animals should be emphasized.
2_
-10
Figure 1.-- Generalized freshwater gammarid amphipod, showing
principal external structures. 1, head; 2, antenna 1; 3, an-
tenna 2; 4, mouth parts (shown in detail in Fig. 2); 5, pereonites
1-7; 6, pereopods 1-7 (including gnathopods 1 and 2); 7, pleonites
1-3; 8, pleopods 1-3; 9, uronites 1-3; 10, uropods 1-3; 11, telson.
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In order to further familiarize the reader with the morphological struct-
ures used in the taxonomy of freshwater gammarid amphipods, each basic
structure, beginning anteriorly, will be defined briefly. Since, in the
past, morphological nomenclature has not always been consistent and
different terms have been employed to designate the same appendage or
external part, a standard usage has been adopted and applied consistently
throughout the following keys. For comparison and further reference, the
reader is referred to an excellent diagnosis of the morphological struc-
tures of the families of marine Gammaridea by Barnard (1969) .
Head region: The head is composed of six completely fused segments (
head segments and the first thoracic segment) and bears one pair of
sessile compound eyes. The latter are often greatly reduced or absent in
the subterranean forms. The interantennal lobe is the small, variously
rounded part of the head situated laterally on either side between the
peduncles of the first and second antennae.
Antenna 1 (one pair): This appendage, sometimes called the antennule in
other crustacean groups, consists of a three -segmented peduncle, followed
by a multisegmented, primary flagellum. The accessory flagellum arises at
the distal end of the third peduncular segment and has several tiny seg-
ments or articles. Small, linear-shaped calceoli are often found on many
of the primary flagellar segments in the subterranean forms.
Antenna 2_ (one pair) : This appendage is made up of five unequal peduncular
segments, followed by a multisegmented flagellum. The second antenna is
typically shorter than the first antenna, and in Crangonyx, Synurella,
and Gamncarus it often bears conspicuous paddle-shaped sensory structures
(calceoli) which are common in males but usually lacking in females.
Mouth parts : Six different structures make up the mouth parts as follows --
the upper lip, one pair of mandibles, two pairs of maxillae (maxilla 1 and
2) , one pair of maxillipeds , and the lower lip.
Pereonites : These are the seven free thoracic segments of the body
making up the pereon and bearing one pair of pereopods each. The first
thoracic segment (not a pereonite) is fused with the head and bears the
maxillipeds of the mouth parts.
Pereopods : Seven pairs of thoracic appendages including the first two pairs
called gnathopods . The gnathopods differ from the other pereopods by being
subchelate. Some workers number the gnathopods separately from the other
pereopods, i.e., gnathopods 1 and 2 and pereopods 1-5. This writer, how-
ever, numbers the pereopods successively from 1 to 7 but refers to the first
two pairs as gnathopods 1 and 2. The spelling of pereopod has been modified
from other spellings, vis., peraeopod or pereiopod. The seven segments or
articles of the pereopods are referred to by number with the following
exceptions: dactyl (s) for segment 7, propod(s) for segment 6, basis (es) for
the expanded second segments of pereopods 5, 6, and 7, and coxa(e) for seg-
ment 1 .
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Brood plates: Four pairs of ventral plates or lamellae arise from in-
side and near the base of the first segment (coxa) of pereopods 2-5.
These structures are characteristic of females and become fringed with
setae at sexual maturity. They are sometimes called oostegites,
marsupial plates, or brood lamellae. During the brooding of eggs,
these plates become interlocked by their marginal setae to form the
brood pouch.
Coxal plates: Seven pairs of lateral plates which are actually exten-
sions of the coxae and which extend downward to cover the coxae and
usually part of the bases.
Coxal gills: These are usually flattened, oblong to subovate struct-
ures, attached to the inside and near the base of the coxae and occur
on pereonites 2-6 and sometimes on 7.
Sternal processes: These structures are usually present in species of
the CTangonyx group but are absent in species of Gammarus and
Allocrangonyx. Sternal processes are sometimes referred to as sternal
gills but whether or not they function as accessary respiratory struct-
ures in all species is debatable. When present, sternal processes
occur as follows: one, two, or three single, slender processes (often
finger-like) on pereonites 2, 3, and 4; a single pair of slender proc-
esses on the first pleonite; and two pairs of laterally placed, simple
or bifurcate processes (often sickle-shaped or lanceolate) on the
ventral surface of pereonites 6 and 7.
Pleonites: The first three segments of the abdominal region containing
laterally placed abdominal side plates (see below) and bearing one pair
of pleopods each.
Abdominal side plates: These occur as paired, lateral plates or
pleurites of the three pleonites and are fused to the body dorsally but
are generally free posteriorly and ventrally. These structures are also
called epimera (singular = epimeron).
Pleopods: Paired, biramous appendages borne by each of the three
pleonites. Two or more small coupling spines (hooks) are found on the
inside distal margin of the peduncles and are used for engaging the
pairs of pleopods.
Uronites: The last three body segments of the abdominal region making
up the urosome and sometimes called urosomites or urosome segments.
These segments, along with pleonites 1-3, are sometimes referred to as
the pleon or metasome. In Gammarus these segments are often humped
mid-dorsally and bear small medial and lateral spines. In Stygoneotes,
Apoorangonyx, and one species of Synwcella they are partially fused or
coalesced.
Uropods: Three pairs of somewhat modified biramous appendages borne by
the uronites and extending posteriorly, or in the case of the third,
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semi-dorsally. Uropod 3 varies considerable intergenerically and is
susceptible to radical modification. In the freshwater Gammaridae-,
uropod 3 varies from a biramous structure with two well developed
rami in Gammarus to a greatly reduced structure that consists of only
a peduncular remnant in some species of Apoerangonyx.
Telson: This flap-like structure is attached to the third uronite a-
bove the anus. It undergoes considerable change from genus to genus
and varies from a deeply cleft, bilobed structure in Gammarus to a
single flap with a complete apical margin in some species of
Stygonectes and Stygobromus.
Figure 2. -- Structure of freshwater Gammaridae. Mouthparts of
Apoorangonyx spp. (modified from Holsinger. 1969b) : a, maxilliped;
b, upper lip; c, right mandible; d, dentate part of left mandible;
e, maxilla 1; f, lower lip; g, maxilla 2. ApocTangonyx araeus:
h, gnathopod 2 (in part) showing attachment of brood plate (BP)
and coxa gill (G).
10
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SECTION II
FAMILY GAMMARIDAE
The family Ganraiaridae is the largest and most widespread member of the
suborder Gammaridea and is represented by numerous genera (ca. 130)
and species. Although the family is found in both marine and fresh
water habitats, it is the only group of amphipods that has invaded
continental freshwaters on such a broad, cosmopolitan basis. Many
genera are exclusively freshwater (ca. 100) and some of these are
exclusively subterranean (ca. 25).
During recent years amphipodologists have designated groups (some-
times called phyletic lineages) within the family. These groups reflect
closely related genera or generic clusters rather than taxonomic cat-
egories in the strict sense. Some workers have suggested that some of
these groups be elevated to subfamilial rank or, in some instances, to
familial rank. Admittedly, the family is somewhat heterogeneous in com-
position and perhaps quite diverse in comparison with other families of
the suborder. But it is the writer's opinion that these groups be re-
tained, at least for the time being, as informal evolutionary catagories
rather than be designated families or even subfamilies.
In North America (north of Mexico), three familial groups have been
recognized. The eight genera of North American Gammaridae with fresh-
water species are arranged within these groups as follows: Gammarus
group -- Gammarus; Crangonyx group -- Cvangonyx, Synuvella, Apoorangonyx,
Stygoneetesj StygobpomuSj and Baotruvus; Alloerangonyx group -.* Alto*-
ovangonyx.
Keys to the various families with freshwater species in North America
have been published by Shoemaker (1942a) and Bousfield (1958). With-
out reference to these keys, however- Gammaridae is easily distinguished
from other families by the following combination of characters (illustra-
ted by Figs 1 and 2).
Body laterally compressed. Antenna 1 usually longer than antenna 2;
accessory flagellum of antenna 1 with 2 to 7 small segments. Mandible
usually with a palp (present in all North American genera north of
Mexico); maxilla 1 with 2-segmented palp. Gnathopods subchelate; per-
eopods 5, 6, and 7 alike in structure but different in length; pereopod
7 about equal to pereopod 6 in length but often a little longer or a
little shorter. Uropod 3 with or without rami, but outer ramus usually
present although often greatly reduced; outer ramus longer than inner
ramus when both rami are present. Telson entire or variously cleft.
11
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Figure 3. -- Structure of freshwater Gammaridae: a, uropod 3 of
Gammapus minus; b, accessory flagellum of G. minus; c, telson of
CTccngonyx antennatus; d, gnathopodal propod of G. minus; e,
uronites of Gammarus acherondytes (based on Bousfield, 1958); f,
telson of G. minus.
12
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Key to Genera of the Family Gammaridae in North America
1 Accessory flagellum of antenna 1 with 2 to 7 segments (usually
3 or more)(Fig. 3b); gnathopodal propod palmar margins with-
out distally notched spine teeth in either sex (Fig. 3d);
uronites with prominent dorsal spines (Fig. 3e); uropod 3
biramous (Fig. 3a), rami well developed] telson cleft nearly
to base (Fig. 3f) : Garmarus (p. 17)
Accessory flagellum of antenna 1 with never more than 2 seg-
ments; gnathopodal propod palmar margins with distally
notched spine teeth in males and usually in females (Fig. 41);
uronites without prominent dorsal spines; uropod 3, inner
ramus reduced to a small scale or absent; telson cleft or
not, if cleft then no more then 3/4 way to base (Fig. 3c) .... 2
2(1) Outer plate of maxilla 1 with 9 apical spines (Fig. 4d); dactyls
of pereopods 6 and 7 with ventral spines (Fig. 4c); sternal
processes absent; uronite 2 with 1 pair of very small dorso-
lateral spines; uropod 3 biramous, outer ramus elongate and
2-segmented: AllooTccngonyx (p. 77)
Outer plate of maxilla 1 with 7 apical pectinate spines (Fig. 2e);
dactyls of pereopods 6 and 7 without ventral spines; sternal
processes usually present (Fig. 4a,b); uronite 2 without
spines; uropod 3 biramous or uniramous, outer ramus not
elongate but reduced to 1 segment or vestigial or absent
(Fig. 4e,f,g) 3
3(2) Antenna 2 of mature male with paddle-shaped calceoli (Fig. 4h);
eyes usually present and pigmented; gnathopodal propod 2
usually larger than 1; pereopod 6 longer than 7; apical margin
of telson distinctly cleft (Fig. 3c) 4
Antenna 2 of mature male without paddle-shaped calceoli; eyes
never present (of subterranean facies); gnathopodal propod
2 smaller, equal to, or larger than, 1; pereopod 7 sometimes
longer than 6; apical margin of telson entire or with a shallow
cleft (Fig. 4i) 5
4(3) Dactyls of pereopods 5, 6, and 7 with 4 to 5 stiff setae or
small spines on inner margins (Fig. 4j); uronites fused or
not; outer ramus of uropod 2 of mature male normal (not
deflected or curled); uropod 3 uniramous, outer ramus not
exceeding length of peduncle (Fig. 4k): Synuvella (p. 49)
Dactyls of pereopods 5, 6, and 7 with typically 1 stiff seta on
inner margins (Fig. 5a) (excepting Crangonysc setodactylus which
has 2 to 3 such setae); uronites not fused (Fig. 1); outer
ramus of uropod 2 of mature male curled or deflected laterally
(Fig. 5b); uropod 3 biramous, outer ramus longer than peduncle,
inner ramus vestigial (Fig. 5d): Cvangonyx (p. 29)
13
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Figure 4. -- Structure of freshwater Gamraaridae: a, bifurcate lateral
sternal process of Apoarangonyx araeus; b, simple lateral sternal process
of Crangonyx paakca'di; c, dactyl of pereopod 7 of Allocpangonyos
pelluaidus; d, maxilla 1 of A. pellucidus; e, uropod 3 of A. araeus;
f, uropod 3 of Apoepangonyx pa^vus; g, uropod 3 of Stygoneotes
aldbamensi-s h, male antenna 2 (showing calceoli) of Crangonyx antennatus;
i, telson of Stygoneotes emarg^natus;j, 7th pereopod dactyl of Synurella
dentata; k, uropod 3 of S. dentata; 1, 1st gnathopodal propod of
Stygonectes allegheniensis.
14
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5(3) Outer lobe of maxilliped with a row of small, blade-like spines
on inner margin (Fig. 5e); pereopod 7 longer than 6; lateral
sternal processes simple, not bifurcate; uropod 1 of mature
male without distal peduncular process; uropod 3 biramous,
inner ramus vestigial; outer ramus about as long as peduncle
(Fig. 5f): Bactruvus (p. 73)
Outer lobe of maxilliped with stiff setae only on inner margin
(Fig. 2a); pereopod 7 longer, equal to, or shorter than 6;
lateral sternal processes bifurcate or not (Fig. 4a); uropod
1 of mature male often with distal peduncular process (Fig. 5c);
uropod 3 uniramous, outer ramus shorter than peduncle and
occasionally absent (Fig. 4e,f,g) 6
6(5) Gnathopodal propod 2 about equal to or usually larger than 1;
pereopod 6 usually longer than 7; lateral processes simple,
not bifurcate (with exception of 1 undescribed species);
uronites not fused: Stygobromus* (p. 65)
Gnathopodal propod 1 often larger, but sometimes equal to or
smaller than 2; pereopod 7 longer than 6; lateral sternal
processes usually bifurcate (with a number of exceptions);
uronites fused or nearly so 7
7(6) Gnathopodal propod 2 equal to or larger than 1; outer ramus of
uropod 3 vestigial or absent (Fig. 4e,f); size range of adults
2.0 to 7.0 mm: Apocrangonycc* (p. 52)
Gnathopodal propod 1 usually larger than 2; outer ramus of uropod
3 small but neither vestigial nor absent; size range of adults,
4.5 to 20.0 mm: Stygonectes* (p. 55)
* These three genera are often difficult to key out because a
number of characters overlap in certain species. With one or two
exceptions, however- Stygobromus and Stygonectes are easily sep-
arated on the basis of diagnostic character combinations. In com-
parison, Apoarangonyx is less distinct and there is some question
as to whether this genus as presently defined is a natural group
or an artificial one (see Holsinger, 1969a, 1969b, and below for
further comments on this problem).
15
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e
figure 5. -- Structure of freshwater Gammaridae: a, dactyl of
pereopod 7 of Crangonyx antennatus; b, male uropod 2 of (7.
antennatus; c, male uropod 1 of Stygoneates indentatus; d, uropod
3 of CTongonyx forbesi; e, maxilliped of Baatviams muovonatus;
£, uropod 3 of B. mueronatus.
16
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GAMMARUS Group
Genus Gammarus (in part) Fabricius, 1775
The genus Gammarus (s. lat.)> as presently understood, is composed of a
number of subgenera and numerous species widely distributed throughout
the Northern Hemisphere. Species occur in shallow marine, brackish,
and freshwater habitats, but the largest number of species inhabit lit-
toral brackish and fresh water biotopes. Considerable taxonomic con-
fusion still exists within the genus, and as implied by Bousfield
(1969) and Stock (1967), a world revision would be both desirable and
necessary for a complete understanding of the systematics of this com-
plex group. The current situation is further complicated by the presence
of sibling species, sympatric ranges, overlapping ecology, extreme
morphological variation, etc., especially among the brackish water forms.
This confusion seems less pronounced, however, among the strictly
freshwater species of the genus, where, despite overlapping ranges and
several as yet unresolved species complexes, most species appear to be
more clearly differentiated. Nevertheless, this may be an
oversimplification of the true picture, especially in parts of the world
where freshwater species of Gcarmarus have not yet been carefully studied.
Nine species are currently recognized from North American freshwaters.
A number of other species have been described but are now regarded as
synonyms (including G. elki which is considered a synonym of G. minus
by this writer, as pointed out below). Two other species, G. ttgrtnus
and G. duebeni3 occur in brackish waters of the Atlantic coastal region
but are occasionally found in marginal freshwater habitats. Only the
strictly freshwater species (including G. fasciatus which may ocasion-
ally occur in marginal brackish waters) are included in this manual.
Recent papers by Bousfield (1958, 1969) treat some of the brackish
water species (such as G. duebeni3 G. tigrinus, G. palustr-is3 and G.
daibeiri,') and the reader is referred to these papers for additional
information.
The past use of the subgenus Rivulogammarus to include some of the North
American freshwater species (viz., G. minus3 G, troglophilusj G.
pseudolirmaeuSj G. bousfi'eldi, etc.) by Shoemaker (1940), Bousfield
(1958), Cole and Minckley (1961), and Holsinger (1969a) should be dis-
couraged. Stock (1969) has recently given valid reasons for rejecting
this name. Any further assignment of freshwater species of Gconmarus to
various subgenera should logically await a much needed revision of the
genus on a world-wide basis (see above).
17
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Figure 6. -- Structure of Gammarus: a, head (showing interantennal lobe)
of G. fasaiatus (based on Bousfield, 1958); b, head of G. minus (based on
Holsinger and Culver, 1970); c, 7th pereopod basis of G. troglophilus
(based on Bousfield, 1958); d, uronites of G. bousfieldi (based on Cole
and Minckley, 1961); e, uronites of G. peoos (based on Cole and Bousfield,
1970); f, abdominal side plates 2 and 3 of G. peoos (based on Cole, 1970a);
g, abdominal side plates 2 and 3 of G, bousfieldi (based on Cole, 1970a);
h, 7th pereopod basis of G. minus; i, 7th pereopod basis of G. fasciatus.
18
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Key to the North American Freshwater Species of Gammarus
1 Antenna 2 richly setose; pereopod 7, distoposterior margin of
basis not forming a free lobe but fusing directly (or nearly
so) to segment proper, junction marked by a cluster of long
setae (Fig. 6i) 2
Antenna 2 not richly setose; pereopod 7, distoposterior margin
forming a free lobe, junction not marked by a cluster of long
setae (Figs 6c,h) (although a few short ones may be present).
4
2(1) Interantennal lobe of head, upper angle acute (Fig. 6a); antenna
2 about as long or often longer than antenna 1; palmar margins
of male gnathopodal propods slightly concave: G. faso-laius
Interantennal lobe, upper angle rounded (Fig. 6b); antenna 2
shorter than antenna 1; palmar margins of male gnathopodal
propods concave (but not strongly) 3
3(2) Male antenna 2 with calceoli; coxal plates 1 and 2, distoanterior
margins with 1-2 short setae; ventral margins of abdominal
side plates 2 and 3 not spinose (Fig. 6g); uronites dorsally
humped (Fig. 6d): G. bousfieldi
Male antenna 2 without calceoli; coxal plates 1 and 2, disto-
anterior margins with 4 to 7 setae; ventral margins of abdomi-
nal side,plates 2 and 3 spinose (Fig. 6f); uronites not
dorsally humped (Fig. 6e): G. peoos
4(1) Posterior margin of basis of pereopod 7 with long setae (Figs. 6c,
7c) 5
Posterior margin of basis of pereopod 7 with short setae (Fig. 6h)
6
5(4) Antenna 2 of both sexes with calceoli; palmar margin of second
gnathopodal propod of male not concave; segments 4-6 of
pereopods 5-7 with numerous long setae among spine clusters;
pereopod 7, posterior margin of basis narrowing evenly to
distal hind lobe (Fig. 6c): G. trogloph-ilus
Antenna 2 of female without calceoli; palmar margin of second
gnathopodal propod of male concave; segments 4^6 of pereopods
5-7 nearly devoid of long setae among spine clusters; pereopod
7, posterior margin of basis becoming concave distally (Fig.
7c): G. pseudolirrmaeus
6(4) Interantennal lobe sharply angled above; antenna 2 without calce-
oli; uronites partially humped dorsally, with 20 to 22 rather
prominent dorsal spines: G. aeherondytes
Interantennal lobe rounded above; antenna 2 usually calceolate in
male; uronites not humped (or not appreciably so) dorsally,
with 10 to 18 rather small dorsal spines 7
19
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7(6) Distoposterior corners of abdominal side plates 2 and 3 weakly
acuminate, not produced (Fig. 7b); second segment of outer
ramus of uropod 3 without plumose setae: G. minus (s. lat.)
This choice will also lead to G. b-pevircamus > a recently de-
scribed species that differs only in a few subtle ways from
G. minus (see remarks below).
Distoposterior corners of abdominal side plates 2 and 3
strongly acuminate, produced (Fig. 7a); second segment of
outer ramus of uropod 3 with plumose setae:
G. lacustris (s. lat.)
a
Figure 7. -- Structure of Gammarus: a, abdominal side plates 2
and 3 of G. lacustris (based on Cole, 1970a); b, abdominal side
plates 2 and 3 of G. minus (based on Cole, 1970a); c, 7th
pereopod basis of G. pseudolimnaeus.
20
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Annotated List of the Species
1. Ganmarus acherondytes Hubricht and Mackin, 1940
Type Locality: Morrisons Cave, Monroe Co., Illinois.
This somewhat rare species is known only from four caves in Monroe Co.,
Illinois and one cave in St. Clair Co., Illinois (Fig. 8). It usually
occurs syntopically with G. troglophilus but is much less common than
the latter. Sexually mature males, up to 20.0 mm; sexually mature
females, 12.0 to 16.0 mm. Clutch size up to 21 eggs (or more?). Very
little is known about the life cycle of this species except that
ovigerous females have been observed in summer and, fall. The species
usually inhabits small cave streams.
2. Gammams bousfieldi Cole and Minckley, 1961
Type Locality: Doe Run, Meade Co., Kentucky.
This is a very distinct species, especially when compared with G. minus3
with which it is often associated. G. bousfieldi is known only from
two streams in northern Kentucky, the type locality and Fern Creek in
Jefferson County (Fig. 8). Sexually mature males, 12.0 to 16.0 mm;
sexually mature females are smaller. Although very little is known
about the life cycle of this species, some important observations on
its ecology and behavior were noted by Cole and Minckley (1961).
3. Gammarus breviramus Bousfield and Elwood, 1971
Type Locality: Small spring-fed stream, west fork of Walker Branch, 3
miles south of Oak Ridge, Anderson Co., Tennessee.
Since this species was only recently described the writer has not had
time to examine the type material. However, on the basis of the descrip-
tion by Bousfield and Elwood (1971) it would appear to be very closely
related to, if not nearly identical to, G. minus3 with which it occurs
sympatrically. The only differences discernible to this writer were the
proportionately shorter uropods 1 and 2 in the male and possibly the
proportionately longer inner ramus of the third uropod. These differ-
ences are subtle at best and are not made clear in the figures given in
the description by Bousfield and Elwood (1971). A brief discussion of
the ecology of this species can be found in Bousfield and Elwood (1971).
G, bpevivamus is known only from the vicinity of its type locality (i.e.,
Walker Branch Watershed streams) where it is less common than G. minus.
4. Gconmcacus fasoiabus Say, 1818
Type Locality: Probably a river in eastern Pennsylvania, the details
of which are lacking in the original description.
This widely distributed species ranges from the upper Mississippi River
drainage eastward throughout the Great Lakes area and south along the
Atlantic Coastal plain to southern North Carolina (Fig. 8). Although
primarily an inhabitant of lakes and rivers (see Bousfield, 1958), this
species also occurs in small streams and occasionally in spring runs,
especially in the southern part of its range. Sexually mature males,
up to 14.0 mm; sexually mature females, 8,0 to 12.0 mm. Bousfield's
1958 comments on the life history of this species hold true in general,
except that ovigerous females have been observed from February to April
in the more southern parts of the range.
21
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6. acherondytes
G. bousf ieldi
G. fasciatus
G. pecos
Figure 8. -- Distribution of species of Gammarus in North America.
22
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As pointed out by Bousfield (1958), this species has been confused with
at least two and possibly three other species of Gcanmavus in the past.
Where the range of G. fasoi-atus overlaps or is contiguous with that of
G. tigrinus in coastal areas of the eastern United States, the two
species can be distinguished by differences in the setation and
spination of the abdominal side plates (Cole, 1970a). Additional dif-
ferences are also given in a key by Bousfield (1969). In the coastal
areas extending from South Carolina westward to Louisiana, G, fasoiatus
is replaced by a complex of two to three closely related species which
has characters in common with both G. fasoiatus and G. tigr-inus.
Hubricht's records for G. fasoiatus from South Carolina and Florida
(Hubricht, 1943) are referrable to this complex, as well as a number of
collections (unpublished data) from Louisiana and Mississippi currently
in the United States National Museum of Natural History.
5. Gcormarus laoustris s. lat.
Two subspecies were recognized by Bousfield as follows:
a) Gammarus lacustris laeustris G.O. Sars, 1864.
Type Locality: Northwestern Europe (specific location unknown).
b) Gammarus I. limnaeus S.I. Smith, 1874
Type Locality: Lake Superior, Ontario, Canada.
During the preparation of this manual, the writer studied numerous
collections of G. laeustris s. lat. from localities in the northern
and western United States, Canada, and Alaska in an attempt to more
clearly delimit the ranges of the two subspecies recognized by Bousfield
(1958). The diagnostic characters used to differentiate these two races,
however, were found to be highly variable and without regional consisten-
cy. For example, some mature specimens from the western United States
(within the range of G. I. lacustr-is} had as many as 18 dorsal spines on
the uronites (range, 10 to 18), sub-reniform eyes, and as many plumose
setae on the second segment of the outer ramus of the third uropod as
that given for the eastern subspecies G. 1. liimaeus. Furthermore, some
specimens studied from well within the range of G. 1. limnaeus had sub-
rotund eyes and as few as 10 dorsal spines on the uronites. Moreover,
in a recent study by Cole (1970a) on the epimera (abdominal side plates)
of North American freshwater species of GammaruSj clear-cut differences
in the shape, armature, and setation of these structures were not de-
monstrated for these two subspecies. Finally, with the exception of the
disjunct populations in Oklahoma, the range of G. laeustris s. lat. ap-
pears to be continuous across North America, and separation into region-
ally allopatric populations seems unlikely. In all fairness, however,
this problem is still far from being solved, and a search for genetic
differences (as opposed to morphological ones) might be in order. Along
these lines, H.B.N. Hynes of the University of Waterloo has attempted to
cross breed members of the two subspecies but so has received
inconclusive results (Bousfield, in litt,).
G. lacustTls s. lat. is found throughout most of the western United
States (especially in the cold alpine lakes of the Rocky Mountain
region), across the northern part of the United States through the Great
Lakes area, throughout most of Canada and Alaska north to the Arctic
23
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Figure 9. -- Distribution of species of Gammarus in North Amer-
ica. The complete range of G. lacustr-is is not shown; it extends
throughout most of Canada and Alaska, north to the Arctic Circle
and to Latitude 70° in some areas.
circle and latitude 70° in some areas (Fig, 9). The species is also
found in northwestern Europe and disjunct populations occur in central
Oklahoma. This species occupies a variety of cold-water habitats, in-
cluding lakes, tundra ponds, streams, sloughs, swamps, and springs.
Sexually mature males range in size from 14.0 to 18.0 mm and occasion-
ally reach 22.0 mm. Sexually mature females reach 14.0 mm and rarely
18.0 mm. Ovigerous females occur from March to September but their
occurrence probably varies somewhat with latitude, water temperature,
etc. Other pertinent comments on ecology can be found in Bousfield
(1958). Gammarus robustus, described from Colorado by S.I. Smith (1874),
is a synonym of G. laeustris as verified by a recent examination of the
types of this species by Mills and Bousfield (Mills, 1964).
24
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6. Gammarus minus Say, 1818
Type Locality (neotype): Small stream at Gable's Woods, Lancaster, Lan-
caster' Co., Pennsylvania.
This common, widely distributed species is found in cave streams,
springs, and spring-runs throughout a large part of the Appalachians,
Interior Low plateaus, and Ozarks (Fig. 9). It is especially common in
areas composed of limestone and dolomitic bedrock. The range was ana-
lyzed in detail in recent papers by Holsinger (1969a), Holsinger and
Culver (1970), and Cole (1970b). Although the presently known range of
this species is disjunct (see range map) and morphological variation is
common (often as great locally as regionally), attempts to find diag-
nostic differences between regionally defined populations that are great
enough or consistent enough to warrant specific recognition have not
been successful. Cole's recent approach to this problem (Cole, 1970b)
in which four major geographic types were defined, appears to be the
most logical solution to date. Cole divided regional populations of G.
minus into: (1) Eastern, including the Piedmont, Appalachians and
Interior Low plateaus; (2) Ozarkian, including the Ozark Plateau of
Arkansas and Missouri; (3) post-Kansan, including western Illinois and
northeastern Missouri (generally to the east and north of the Ozark
Plateau); and (4) Pine Hills region of southern Illinois, desig-
nating these populations as a subspecies he called G. m. piniaollis.
In another paper dealing with the morphological variation in G. minus,
Holsinger and Culver (1970) demonstrated that the variety tenu-ipes
(described by Shoemaker, 1940) was an ecophenotype that did not
merit taxonomic recognition. The variety tenu-ipes, referred to as
Form 1 by Holsinger and Culver, is a degenerate-eyed, subterranean form
that inhabits certain large cave systems of two karst areas in the
Applachian valley of Virginia and West Virginia. Detailed information
on the morphology and ecology of G. minus can be found in recent papers
by Minckley and Cole (1963), Holsinger and Culver (1970), Cole (1970b),
and Culver (1970). Sexually mature males range in size from 8.0 to
14.0 mm, but usually from 8.0 to 12.0 mm. Sexually mature females range
in size from 5.0 to 12.0 mm, but usually from 6.0 to 10.0 mm. Females
normally produce from five to 15 eggs per clutch, depending on size;
very small females sometimes produce fewer than five eggs and very large
females sometimes produce more than 15 but rarely more than 20 eggs.
Two species, Garmarus propinquus and G. pwcpwcasoens, were described
by Hay (1902, 1903) from a spring near Mammoth Cave, Kentucky and the
resurgence of Nickajack Cave, Tennessee, respectively. Both species
were subsequently synonymized with G. minus by Shoemaker (1940). A
third species, Gconmarus efki, was described from Benton Co., Arkansas
and McDonald Co., Missouri by Reimer (1969), but in the opinion of
the writer, this species should also be considered a synonym of G.
minus. A recent examination of the type series of G. elki failed to
reveal any significant differences from other Ozarkian populations of
G. minus. While the type material is somewhat aberrant, it easily
falls within the acceptable limits of morphological variation usually
attributed to G. minus.
25
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G. pseudolimnaeus
G. troglophilus
Figure 10. -- Distribution of species of Gcarmarus in North America.
26
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7. Gammarus pesos Cole and Bousfield, 1900
Type Locality: Willbank Spring near Fort Stockton, Pecos Co., Texas.
This species was recently described from two localities (a spring and
a stream) in the Pecos River drainage of western Texas (Fig. 8).
Other than a few brief notes given by Cole and Bousfield in the origi-
nal description, very little is known about the ecology of this species.
Mature males, 12.0 to 14.9 mm; mature females 9.0 to 11.0 mm. G. peoos
appears to be only one of several closely related species which comprise
a species complex that extends from Pecos County north to Chaves, New
Mexico. The complex is presently being investigated by G.A. Cole of
Arizona State University.
8. Gcanmcacus pseudolimnaeus Bousfield, 1958
Type Locality: Rideau River below Hog's Back, Ottawa, Ontario, Canada.
The range of this widely distributed species extends from western Quebec
across Ontario into central New York, throughout the Great Lakes region
of Michigan, Wisconsin, and Illinois, and west and southwest into
eastern Iowa, central Missouri, northeastern Oklahoma, northern Arkansas,
western Kentucky, and northwestern Tennessee (Fig. 10). Disjunct records
from Prince Georges Co., Maryland (U.S. National Museum collection) and
the Texas Coast (Bousfield, 1958) may represent introductions or
mislabelled samples, since these sites are far out of the boundaries of
the known range. G. pseudolimnaeus is rather common in springs and some-
times in cave streams in eastern Iowa, southwestern Illinois, eastcentral
Missouri, and northern Arkansas. In the more northern part of its range,
especially in the Great Lakes region, it is often found in streams. In
springs, this species occurs syntopically with G. minus (s. lat.) in
Arkansas, eastern Missouri, southwestern Illinois, western Kentucky, and
northwestern Tennessee. It is also associated with G. tToglophilus in
southwestern Illinois and eastern Missouri. Sexually mature males reach
17.0 mm; sexually mature females reach 14.0 mm but some may reach maturi-
ty at only 6.0 mm.
Ovigerous females have been collected during every season of the year,
implying that breeding is continuous throughout the year. According to
Bousfield (1958), the life span is approximately 16 months.
9. Ganrnarus troglophilus Hubricht and Mackin, 1940
Type Locality: Morrisons Cave, 2 miles south of Burksville, Monroe Co.,
Illinois.
This large species is common in cave streams and springs in southwestern
Illinois (recorded from 10 counties) and eastern Missouri (recorded from
10 counties) (Fig. 10). It sometimes occurs syntopically with G.
pseudolimnaeus and G. minus (s. lat.), although rarely with the latter
in the Missouri part of the range. In Monroe and St. Clair counties,
Illinois, this species is sometimes associated with G. aoherondytes.
Largest males reach 24.0 mm; largest females reach 19.0 mm. G. tvo-
glophilus apparently breeds the year around, as ovigerous females have
been collected during every season. Weise (1953), however; in a study of
the life cycle and ecology of this species, assumed, on the basis of juve-
nile frequency, that the breeding season extended from November to April.
27
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CRANGQNIX Group
Genus Crangonyx Bate, 1859
This genus occurs predominately in North America where it is represented
by 18 described species. Approximately 20 to 25 species and subspecies
are undescribed. Although eight species have been assigned to Crangonyx
from outside of North America, only three or four of these appear to
be valid members of the genus; the remainder should be assigned to dif-
ferent genera. One of these species, Cvagononyx robeTtsi- from subter-
ranean habitats in South Africa, constitutes a new genus and is currently
being described by Holsinger and Straskraba (in preparation). The species
of Cvangonyx from outside of North America are mostly subterranean forms
from Europe (one or two species), the Urals of the USSR (one species), and
the Ussuri River basin of the USSR (one species).
The 18 North American species of Crangonyx can be assigned to six species
groups on the basis of morphological similarities. Bousfield (1958)
alluded to some of these groups but did not recognize them formally-
Pending a major revision of the genus now in preparation, these groups
should be regarded as temporary and not formal taxonomic categories. They
are presented here as an aid in delineating possible phyletic lineages
within the genus.
1. Anomalous group: C. anomalus
2. Forbesi group: C. forbesi
3. Graoilis group: C. flom-danus^ C. grao-ilis} C. paokardi (emended from
paokardii,}, C. pseudog?>aoi'1'is3 and C. rivulapis.
4. Hobbsi group: C. hobbs-i
5. Obliquus-richmondensis group: C. alp-inuSj C. dearolf-ij C. grandimanus3
C. obliquus, C. riofanondens-is s. lat., C, serratus3 and possibly C.
antennatus.
6. Shoemakeri group: C. setodaotyluSj C. shoemakeri^ and C. minor.
Key to the North American Species of Crangonyx
1 Gnathopodal propods of female proportionately small, palmar margins
lined with very small, weak (usually distally un-notched) spines
(Fig. Ha); superior lateral setae of gnathopodal propod 2 singly
inserted 2
Gnathopodal propods of female usually proportionately larger, pal-
mar margins lined with typically strong, distally notched, spine
teeth (Fig. 12a,g); superior lateral setae in transverse groups
of 1, 2, 3 or more 7
2(1) Posterior margins of bases of pereopods 5, 6, and 7 weakly serrate
(Fig. lib); distoposterior margins of abdominal side plates not
produced, corners weakly acuminate and nearly truncate in plate
3: C. r-Lvularis
Posterior margins of bases of pereopods 5, 6, and 7 distinctly ser-
rate; distoposterior margins of abdominal side plates 2 and 3
produced, corners usually acutely produced 3
28
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Figure 11. -- Structure of Cvangonyx: a, 1st gnathopodal propod
of female of C. paakard-i; b, basis of pereopod 7 of C. paokardi;
c, abdominal side plate 1 of C, paokavdi; d, gnathopod 2 (in
part) of female of C. hobbsi; e, basis of pereopod 7 of C. hobbsi;
f, abdominal side plate 1 of C. flovidanus (based on Bousfield,
1963b); g, male uropod 2 of C. shoemdkeri; h, abdominal side plate
2 of C. pseudogvacil'is; i, telson of C. forbesi; }, dactyl of
pereopod 7 of C. setodaotylus,
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3(2) Gnathopodal propods of female long and narrow, twice as long as
broad (Fig. lid); segment 5 of second gnathopod elongate,
longer than segment 6 (propod) in female and as long as propod
in male; distoposterior lobe of basis of pereopod 7 large and
broadly rounded (Fig. He); eyes and pigment degenerate to
absent (of subterranean facies): C. hobbsi
Gnathopodal propods of female not especially elongate or narrow,
segment 5 not as long as propod; distoposterior lobe of basis
of pereopod 7 not exceptionally large or broadly rounded; of
subterranean facies or not 4
4(3) Distoposterior corner of abdominal side plate 1 strongly mucronate
(Fig. llf); sexually mature females reaching 6.5 or 7.0 mm:
S. flop-idanus
Distoposterior corner of abdominal side plate 1 weakly mucronate
(Fig. He); sexually mature females reaching 11.0 mm in epigean
forms and 5.0 to 8.0 mm in hypogean forms 5
5(4) Mature males without row of comb spines on outer ramus of uropod 2
(Fig. 5b): C. grae-Llis complex
(includes a number of closely related undescribed species)
Mature males with row of comb spines on outer ramus of uropod 2
(Fig. llg) 6
6(5) Eyes degenerate or absent; pigment reduced or lacking; disto-
posterior corner of abdominal side plate 2 very weak1.
C. paokardi
Eyes not degenerate, pigment present; distoposterior corner of
abdominal side plate 2 strongly acute (Fig. llh):
C. pseudogvaci.l'is complex
(includes a number of closely related undescribed species)
7(1) Gnathopodal propods of female moderately small, not much expanded
distally, palmar margin straight to slightly concave; inner
margin of dactyl of female gnathopodal propod 2 with a row of
blade-like spines (Fig. 12a); distoposterior corners of abdomi-
nal side plates weakly acuminate 8
Gnathopodal propods of female moderately large, somewhat expanded
distally, palmar margins usually straight or convex; dactyl of
female gnathopodal propod 2 without a row of blade-like spines
on inner margin (Fig. 12g); distoposterior corners of abdominal
side plates acute or not 10
8(7) Palmar margin of gnathopodal propod 2 straight; dactyls of
pereopods 3-7 with 2 to 3 short, stiff setae on inner margins
(Fig. llj): C. setodaotylus
Palmar margin of gnathopodal propod 2 concave; dactyls of
pereopods 3-7 with typically 1 stiff seta on inner margins... 9
30
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9(8) Mature females with 12 to 15 small, distinct spines on anterior
margin of pereopod 7 basis (Fig. 12b); outer ramus of uropod
2 of sexually mature males without inner row of comb spines:
C.
Mature females with only about 8 weak spines on anterior margin
of pereopod 7 basis (Fig. 12c); outer ramus of uropod 2 of
sexually mature males with inner row of comb spines (Fig.
Hg)". C. shoemakeri,
10(7) Propod of gnathopod 2 proportionately very large, nearly 2
times size of 1; bases of pereopods 5, 6, and 7 greatly ex-
panded posteriorly, posterior margin broadly convex and with
numerous minute serrations (Fig. 12f); apical lobes of telson
with 5 to 6 spines each (Fig. 12k); sexually mature males
larger than sexually mature females: C. anomalus
Propod of gnathopod 2 larger than 1 but not twice as large;
bases of pereopods 5, 6, and 7 not greatly expanded; pos-
terior margins with fewer serrations; apical lobes of telson
with 2 to 4 spines each; sexually mature males smaller than
sexually mature females: 11
11(10) Lacking pigment; eyes degenerate to absent; of subterranean
f acies 15
Eyes and pigment well developed; not of subterranean facies.... 12
12(11) Bases of pereopods 5-7 with deeply serrated posterior margins
(Fig. 12e); ventral margin of abdominal side plate 2 of
female with up to 11 spines; telson significantly longer than
broad, deeply cleft, with spines dorsally as well as apically
(Fig. 12j): C. serratus
Bases of pereopods 5-7 with shallow serrations in posterior
margins; ventral margin of abdominal side plate 2 of female
with up to 6 spines; telson not much longer than broad, with-
out dorsal spines 13
13(12) Posterior margin of second gnathopodal propod rather long, with
7 to 10 sets of setae; superior lateral setae of second
propod in sets of 4 or more (Fig. 12g); posterior margin of
basis of pereopod 7 with 16 to 25 fine serrations;
distoposterior corners of abdominal side plates small, acute
and recessed; uropod 3 rather short, with 3 sets of lateral
spines per side; telson short, shallow cleft, with 3 to 4
apical spines per lobe (Fig. Hi): C. forbesi
Posterior margin of second gnathopodal propod not so long, with
4 to 6 sets of setae; superior lateral setae of second propod
usually in sets of 2's and 3's; posterior margin of basis of
pereopod 7 with 10 to 20 moderately deep serrations; disto-
posterior corners of abdominal side plates produced and
acuminate; uropod 3 proportionately longer- with 4 to 5 sets
of lateral spines per side; telson about as long as broad,
with 2 to 3 apical spines per lobe 14
31
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Figure 12. -- Structure of Crangonyx: a, female 2nd gnathopodal
propod (palmar region) of C. shoemakeri; b, basis of pereopod 7
of C. minor (based on Bousfield, 1958); c, basis of pereopod 7
of C. shoemdkeri; d, basis of pereopod 7 of C. obliquus; e, basis
of pereopod 7 of C. sevTatus; f, basis of pereopod 7 of C.
anomalus; g, 2nd gnathopodal propod of C. forbesi; h, abdominal
side plates 2 and 3 of C. grand-imanus; i, uropod 3 of C. obl-iquus;
j, telson of C. serratus; k, telson of C. anomalus.
32
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14(13) Posterior margin of basis of pereopod 7 with 7 to 9 rather deep
serrations; uropod 3 with 4 sets of lateral spines per side;
telson shallowly cleft, with 2 apical spines per lobe (based
on females only): C. alpinus
Posterior margin of basis of pereopod 7 with 10 or more rather
deep serrations (Fig. 12d); uropod 3 with 4 to 5 sets of
lateral spines per side (Fig. 12i); telson usually more
deeply cleft, with 2 to 3 (usually 3) apical spines per
lobe: C. dbliquus-Tiohmondensis complex
(including C. obliquus, C.r. riehnondensis3 C.r. lawcentianus3
C.r. oeo-idental-is; see remarks below)
15(11) Palmar margins of gnathopodal propods oblique and convex;
superior lateral setae of propods in sets of 2's and 3's;
sexually mature animals from 15.0 to 22.0 mm long 16
Palmar margins of gnathopodal propods not as oblique, straight
to slightly concave; superior lateral setae of propods mostly
singly inserted; sexually mature animals 7.0 to 14.0 mm long:
C. antennatus
16(15) Propod of gnathopod 2 subovate, nearly 2 times size of 1; disto-
posterior lobe of basis of pereopod 7 large and broadly round-
ed; abdominal side plates 2 and 3 distinctly produced
distoposteriorly (Fig. 12h): C. grandimanus
Propod of gnathopod 2 not subovate (broadest distally), not 2
times size of 1; distoposterior lobe of basis of pereopod 7
not broadly expanded; abdominal side plates 2 and 3 not pro-
duced distoposteriorly but with small acute corners:
C. dearolfi
Annotated List of the Species
1. CTangonyx alpinus Bousfield, 1963a
Type Locality: Ledge Lake, Lane Co., Oregon.
This species is known only from alpine lakes in Lane and Douglas counties,
Oregon and is described on the basis of mature females (Fig. 18). Largest
females = 10.5 mm. Details on the life cycle are not available.
2. Cragnonyx anomalus Hubricht, 1943
Type Locality: Spring on Bryan Station Road, 0.3 mile northeast of Eastin
Road, 3 miles northeast of Lexington, Fayette Co., Kentucky.
A large, unique species, easily distinguished from all other members of
the genus in North America by sexually mature males being larger than sex-
ually mature females. This species is an inhabitant of springs and spring-
fed streams in northcentral Kentucky, southeastern Indiana, and south-
western Ohio (Fig. 15). It occurs regularly with C. setodacfylus (but is
much less common) and is sometimes found in company with C. gracil-is group
species and Synurelta dentata. Largest males = 22.0 mm; sexually mature
females, 13.0 to 19.0 mm. Newly hatched young = 2.0 mm. Ovigerous females
are found in winter and early spring but little other information is avail-
able on the life cycle.
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3. Crangonyx antennatus Packard, 1881
Type Locality: Nickajack Cave, Marion Co., Tennessee.
This rather common troglobitic species ranges from the upper Tennessee
River basin in Lee, Scott, and Wise counties, Virginia south-southwest-
ward to northeastern Georgia (into the upper Alabama River basin) and
west along the Tennessee River valley to northwestern Alabama and
extreme southcentral Tennessee; it is also in the Sequatchie River
valley of Tennessee (Holsinger, 1969a) (Fig. 13). The eyes of this
species are degenerate (a few pigmented specks) to absent. C. antenna-
tus occurs in cave pools and small cave streams and is especially common
in the caves of Lee Co., Virginia and Claiborne Co., Tennessee, where it
is often associated with the troglobitic isopod Asellus reeurvatus.
Sexually mature males range in size from 4.5 to 10.0 mm but most are
between 5.0 and 8.0 mm. Sexually mature females range in size from 5.5
to 13.5 mm but the average is between 7.0 and 10.0 mm. Newly hatched
young = 1.5 mm. Life span is of at least three years and perhaps longer.
In the northern part of the range at least,.continuous breeding through-
out the year is indicated by the presence of ovigerous females during
all four seasons. Apparently only a very small percentage of the
individuals of a given population can breed at any one time (Holsinger,
in preparation).
4. Crangonyx dearolfi Shoemaker, 1942a
Type Locality: Hobo Cave, Warnersville, Berks Co., Pennsylvania.
This rare troglobitic species is occasionally found in caves of south-
eastern Pennsylvania (four caves) and central Maryland (three caves)
(Fig. 13). It occurs in cave pools (some of which are temporary) and
has degenerate eyes. Sexually mature males, 15.0 mm; sexually mature
females, 19.0 to 22.0 mm. Newly hatched young = 3.5 mm. Virtually
nothing is known about the life cycle except that a single ovigerous
female was collected in January from a cave in Maryland.
5. Crangonyx floridanus Bousfield, 1963b
Type Locality: Cypress swamp, Highlands Hammock State Park, Highlands Co. ,
Florida.
This species is disjunctly distributed from central Florida (Highlands
County) through western Florida (Jackson County) to eastern Louisiana
(St. Tammany Parish) (Fig. 15). A possible subspecies occurs in
groundwater habitats in southern Florida (i.e., a well near Miami).
C. flovidanus inhabits swamps, ponds, and cave pools. Specimens from
caves often have smaller (degenerate) eyes. This species is rather
common in Gerards Cave, Jackson Co., Florida, where it is found in pools,
and, on one occasion, was removed from the gut of the troglobitic
salamander Ha-ideotriton wallaoei. Sexually mature males, 3.0 to 8.0 mm;
sexually mature females, 5.0 to 10.0 mm. Ovigerous females have been
collected during the months of February through October, thus indicating
that breeding possibly occurs the year around.
34
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C. antennatus
C. dearolfi
C. hobbsi
Figure 13. «- Distribution of species of Crangonyx in North America.
35
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6. Crangonyx forbesi (Hubricht and Mackin, 1940)
Type Locality: Outlet of drain, Osage Hills Golf Course, Kirkwood, St.
Louis Co., Missouri.
A rather large, somewhat variable species that is common in cave streams,
springs, and occasionally in small surface streams and ponds in
eastcentral Missouri and southwestern Illinois (Fig. 14). Populations
from similar habitats in southcentral and southwestern Missouri, northern
Arkansas, and northeastern Oklahoma, all referred to this species by
Hubricht and Mackin (1940) and Hubricht (1943), differ from C. forbesi s.
str. in several important characters and may represent a closely related,
undescribed species. C, forbesi is commonly associated with Gammarus
tvoglophilus and occasionally with Gcmmarus acherondytes and Baetrurus
braahyoaudus in the cave streams of southern Illinois and eastern Missouri.
This species is about as common in springs as it is in caves and does not
show an appreciable loss of pigment or eye structure when it occurs in
caves. The size is quite variable; sexually mature males range from 10.0
to 18.0 mm and sexually mature females from 14.0 to 22.0 mm. Newly
hatched young = 2.0 to 3.0 mm in length. Ovigerous females are known
from all four seasons, implying that breeding is continuous throughout the
year. A possible subspecies of C. forbesi occurs to the east of Illinois
and is found in westcentral Kentucky, southwestern Ohio, and central and
southern Indiana. This form inhabits caves and springs and differs from
C. fovbes-t s. str. only in a few minor points.
7. Cvangonyx gvaci>1'is S.I. Smith, 1871
Type Locality: Lake Superior near St. Ignace Island, Ontario, Canada.
Bousfield (1958) summarized most of the useful information on this species
and clarified its vague status. The range limits of C. graci-l-is are still
not known precisely, and, for this reason, a range map is not included.
Bousfield (1958) published a number of valid records from Ontario and
Quebec, Canada and pointed out that this species probably ranges throughout
the Great Lakes drainage basin, occurring in lakes, permanent ponds, pools,
streams and swamps. The writer has seen additional samples from Ohio and
Wisconsin. Numerous collections from the eastern and southeastern United
States have been identified as C. grac-ilis and many of these have been
published as records for the species (Hubricht and Mackin, 1940; Hubricht,
1943), However, it is the writer's opinion (as well as that of Bousfield)
that C, gracilis s. lat. represents a complex of species and subspecies
and that C. gTaailis s. str. (in the sense of S.I. Smith, 1871 and
Bousfield, 1958) is probably restricted to the Great Lakes region. Many
of the published references to this species (in addition to those of
Hubricht) are in error. At least one closely related species occurs in
the Truckee River of western Nevada, while another undescribed form occurs
in swamps and pools in the Tidewater area (Coastal plain) of south-
eastern Virginia. In C. graoilis s. str., sexually mature males range in
size from 4.5 to 6.5 mm and sexually mature females from 6.0 to 10.5 mm.
Nothing specific is known about the life cycle of this species.
36
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;:*:+:: A- C. forbesi s. str.
'''''-'-' B C. forbesi subsp. ?
C. serrotus
Figure 14. -- Distribution of species of Cr>angonyx in North America
37
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C. floridanus
C. anomalus
C. rivularis
Figure 15, -- Distribution of species of Crangonyx in North America
38
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C. grandimanus
C. packardi
Figure 16. -- Distribution of species of Crangonyx in North America.
39
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C. obliquus-richmondensis
complex
C. richmondensis laurentianus
Figure 17. -- Distribution of species of Crangonyx in North America
40
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8. Cvangonyx grandimanus Bousfield, 1963b
Type Locality: Indian Cave, 7 miles southwest of Ocala, Marion Co.,
Florida.
This large, distinct troglobitic species is known only from three
localities, two caves and one well in central and southern Florida
(Fig. 16). In the structure of its gnathopods and mouth parts, this
species appears to be closely related to Crcmgonyx obliquus. C.
grandimanus is often associated with C. hobbsi, but the latter is
usually more abundant. Sexually mature males, 8.0 to 13.0 mm;
sexually mature females, 10.0 to 15.0 mm. Ovigerous females have been
collected during February, March and December and sexually mature
females have also been noted in October samples. Apparently breeding
is continuous throughout the year but additional biological data are
very sketchy at the moment.
9. Crangonyx hobbsi Shoemaker, 1941
Type Locality: Huggins Cave, Alachua Co., Florida.
This very distinct, rather highly specialized troglobitic species is
easily distinguished by the narrow, elongate fifth and sixth segments of
the gnathopod propods (especially in the female). C. hobbsi is known
from caves and wells in the central limestone region of Florida and from
a well in Dade Co., Florida (Fig. 13). It is sometimes associated with
C. grandimanuSj the latter being much less common. Largest males, 9.0
mm; sexually mature females, 7.0 to 11.0 mm. Breeding apparently takes
place the year around but ovigerous females are never abundant at any
given time.
10, Crangonyx minor Bousfield, 1958
Type Locality: Stony Creek, 4 miles west of Tillsonburg, Oxford Co.,
Ontario, Canada.
This species is closely related to C. shoemakeri but can be distinguished
from the latter by the lack of comb spines on the outer ramus of uropod 2
of the male and by its geographic distribution. C. minor inhabits a va-
riety of aquatic habitats, including small streams (temporary and perma-
ment), sloughs, ditches, drains, springs, and ponds. It appears to be
more common in small streams than in other habitats, however. This
species is recorded from southeastern Iowa, central Illinois, westcentral
Indiana, with disjunct populations in southern Illinois, southeastern
Michigan, northwestern Missouri, and southern Ontario (Fig. 19). Many of
Hubricht's 1943 middlewestern United States records for C. shoemakeri
were actually this species. Sexually mature males, 5.0 to 8.5 mm; sexu-
ally mature females, 8.5 to 12.5 mm. Ovigerous females occur from March
to June but little else is known about the biology of this species.
41
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C. alpinus-
C. ri chmondeasis occidentals
Figure 18. -- Distribution of species of Crangonyx in North America.
42
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11. and 12. Crangonyx obliquus-Tiokmondensis complex, including:
a) Crangonyx obliquus (Hubricht and Mackin, 1940)
Type Locality: Small creek west of the college chapel, Clarksville,
Johnson Co., Arkansas.
b) Crangonyx Tiokmondensis Tiokmondensis Ellis, 1940
Type Locality: Pond on Richmond Plantation, Cordesville, Berkeley,
Co., South Carolina.
c) Crangonyx T. oooidentalis Hubricht and Harrison, 1941
Type Locality: Echo Lake, just south of King Co. line, Washington.
d) CTangonyx r. laurentianus Bousfield, 1958
Type Locality: Black Lake, Gatineau Park near Kingsmere, Quebec,
Canada.
The present systematic status of C. obliquus vis-a-vis C. Tiokmondensis
is unclear. Hubricht and Mackin (1940) described C. obliquus from a
single female taken from a small creek in Johnson Co., Arkansas. Ellis
(1940) described C. Tiokmondensis from specimens taken from a pond in
Berkeley Co., South Carolina. Hubricht (1943) synonymized C.
Tiokmondensis with C. obliquus and listed numerous new records for C.
obliquus from the eastcentral and southeastern United States (Fig. 17).
Bousfield (1958) did not agree with Hubricht, however, and resurrected
C, Tiokmondensis from synonymy, giving reasons (based on descriptions
of these species and not on examination of type material) for its
status as a separate taxon. Bousfield (1958) also recognized three
subspecies of C,. Tiokmondensis C. T. Tiokmondensis from the eastern
United States and Canada; C. T. laurentianus from Michigan, southcentral
Ontario and western Quebec (Fig. 17) and C. r>. oooidentalis (formerly
considered a full and separate species) from British Columbia and
Washington state (Fig. 18).
During the preparation of this manual, the writer examined numerous
collections of obliquus-Tiokmondensis group material and reached the
following conclusions. The material from the vicinity of the type
locality of C. obliquus is very similar to the topotypic material of
C. Tiokmondensis. Despite a slight variation in the shape of the
gnathopodal propods of both sexes, there is no significant taxonomic
difference between the Arkansas populations and the South Carolina ones.
The slight variation noted in the structure of the gnathopods may be
clinal and worthy of subspecific recognition, but this is still unclear
amd must await further study. The material from Nova Scotia and
Newfoundland assigned to C. T. Tiokmondensis by Bousfield (1958) and
material subsequently examined by the writer from New England differs
in several minor but consistent ways from topotypic material of C.
Tiokmondensis from South Carolina and may well constitute a distinct
subspecies. The populations of the Great Lakes region, designated C. T.
laurentianus by Bousfield (1958), are also subspecifically distinct as
described. Moreover, several populations from central New York appear
to be intergrades between the Great Lakes lauTentianus form and the New
England-southeastern Canada Tiokmondensis form. Several other, possi-
bly isolated, population clusters of C. Tiokmondensis s. lat. occur in
the eastcentral and eastern United States (see range map), but their
specific or subspecific status is still vague. The populations from
43
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southwestern Canada and northwestern United States (i.e., C. r. ooo-iden-
talis'} may well represent a separate species from the eastern form(s)
of C. obliquus-richmondensis. Other than minor morphological differ-
ences, already pointed out by Bousfield (1958), these populations are
geographically far removed and presumably well isolated from the eastern
races. It is apparent, in view of the results of the writers recent
investigation, that the taxonomy of the obliquus-r'iolvnondensi,s group
will have to be revised before anything more definitive can be said about
it.
The following notes on ecology and biology apply to the eastern and
eastcentral races of the C. obliquus-riekmondensis complex (i.e., ex-^
eluding C. v. oaaidentalis3 details about which can be found in Bousfield
(1958). Sexually mature males, 7.5 to 11.0 mm; sexually mature females,
12.0 to 20.0 mm. Newly hatched young = 2.0 to 3.0 mm. This form occurs
in a variety of habitats, including small streams (temporary and perma-
nent), sloughs, swamps and bogs, ditches, ponds, drains, and in the
shallow margins of small (often acidic) lakes. Ovigerous females occur
from about January to June, after which only immature amimals are found
throughout the summer and fall. Life span of about one year. See also
papers by Sprules (1967) and Judd (1963) for pertinent information on the
ecology of this species in Canada. In the southern United States, C.
obl-iquus (s. str.?) is often found in company with an undescribed species
of the Crangonyx graoilis group and Synurella bifurca. The populations
of C. vichmondens-is from South Carolina are often associated with
Cvangonyx servatus.
13. Crangonyx paekardi S.I. Smith, 1888
Type Locality: Wells at Orleans, Orange or Lawrence Co., Indiana.
Although this species was regarded by Hubricht (1943) as a subspecies of
C. graailiSj it is clearly a distinct subterranean species, and one, which,
after careful study, may turn out to be a complex of closely related
species and/or subspecies. Material from the vicinity of the "type
locality" in southern Indiana was studied and proved useful in determining
the validity of this species. The range of this species extends through-
out most of the cave and karst regions of southern Indiana and central
Kentucky (Fig. 16). C. paekardi, is found in pools and small streams of
caves where it is often associated with isopods (Asellus spp.) and
Stygobromus spp. (in Kentucky). A form, possibly subspecifically distinct
from C. pa.eka.rd-i, occurs in the caves of the Bluegrass area of northcentral
Kentucky. Other subspecies, or perhaps very closely related species, occur
in caves and other subterranean habitats in northeastern Kentucky and
southern Ohio, in southern Illinois, and in eastern Kansas. A distinct,
but related species, inhabits caves along the western margin of the
Cumberland Plateau in Kentucky. Based on the presence of comb spines on
the outer ramus of the second uropod of the male, C. packdrd-i s. str. ap-
pears to be more closely related to C. pseudograoilis than to C. graoilis.
The following ecological notes are based on southern Indiana-central Ken-
tucky cave populations (C. paokardi s. str.). Sexually mature males, 4.5
to 7.5 mm; sexually mature females, 4.0 to 8.5 mm (possibly reaching sexual
maturity at a smaller size in the more northern parts of the range). Newly
-------
C. minor
C. setodactylus
C. shoemaker!
Figure 19. -- Distribution of species of Crangonyx in North America
45
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hatched young = 1.5 nun. Ovigerous females have been observed during all
seasons of the year, indicating that breeding is continuous throughout
the year as is apparantly true of most of the other subterranean species
of the genus.
14. Crangonyx pseudograeilis Bousfield, 1958
Type Locality: Napanee River at Napanee, Lennox and Addington Co.,
Ontario, Canada.
As pointed out by Bousfield (1958), this species was previously confused
with the superficially similar C. graoilis. The presence of a row of ^
comb spines on the outer ramus of the second uropod of the male, combined
with several more subtle characters (see Bousfield, 1958), serve to
differentiate this species from C. graoilis, however. The presently
known range of C. pseudograoilis is spotty but indicates a wide distri-
bution in the United States and southern Canada. Outside of the range
given by Bousfield (1958), this species has been reported from Oregon by
Bousfield (1961) and from Connecticut by Mills (1964) (Fig. 20). The_
writer has also seen several collections from as far south as Mississippi
which have many characters in common with C. pseudograoilis s. str. ^Fur-
ther, more critical examination may well reveal that C. pseudograoilis is
a complex of several very closely related species. Therefore, at the
moment it is impossible to accurately delimit the range of this species
with any more certainty than is shown on the distribution map herein.
Data on the ecology of this species have been usefully summarized by
Bousfield (1958) and will not be repeated here. Sexually mature males,
4.5 to 6.5 mm (and possibly to 9.0 rarely); sexually mature females, 7.5
to 10.5 mm.
15. Crangonyx rivularis Bousfield, 1958
Type Locality: Rocky Saugeen River, 4 miles north of Durham, Grey Co.,
Ontario, Canada.
This species is to date known only from southeastern Ontario, Canada
(Fig. 15) and nothing new has been added on its ecology and distribution
since first reported by Bousfield (1958). Sexually mature males, 3.5 to
4.5 mm; sexually mature females, 5.5 to 7.0 mm.
16. Crangonyx setodaotylus Bousfield, 1958
Type Locality: Spitler Creek, 4 miles north of Norwich, Oxford Co.,
Ontario, Canada.
This rather large species of the shoemakeri group is easily distinguish-
ed from all other species of the genus by the presence of two to three
short, stiff setae on the inner margin of the dactyls of pereopods 3-7
Many of the records listed by Hubricht (1943) for C. shoemakeri from the
eastcentral United States (especially Kentucky.. Indiana and Ohio) are
actually this species. The range of C. setodaotylus extends from south-
eastern Ontario south and west across southern Michigan through western
Ohio, eastern Indiana and into northcentral Kentucky (Fig. 19). In
Ontario, Michigan and possibly in Indiana, its range overlaps with that
of C. minor to which it is closely related. This species is found in a
variety of cold-water habitats, including small streams, outlets of
drains, springs, sloughs and temporary pools. C. setodactylus is very
46
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common in the springs and spring runs of northern Kentucky (Bluegrass
region) and southwestern Ohio, where it is usually associated with
Syma>e11a dentata^ and sometimes with Crangonyx anomalus and
Crangonyx spp. of the graailis group. In these associations, C.
setodaetylus is usually first in the order of abundance, followed by
S. dentata. C. anomalus and C. spp. are usually much less abundant.
Sexually mature males, 8.0 to 12.0 mm; sexually mature females, 10.0
to 17.0 mm. Breeding in most populations appears to occur in the
winter, followed by ovigerous females in the spring (March to May or
June). The newly hatched young are released in the late spring and
immatures occur during the summer and fall. Occasionally, however,
breeding may take place in the fall as indicated by a collection from
a spring in Kentucky that was made in November and contained ovigerous
females. Life cycle of probably one year.
18. CTangonyx shoemakeri (Hubricht and Mackin, 1940)
Type Locality: Pools along the Potomac River, 2 miles west of Georgetown,
Washington, D. C.
This species is closely related to C. minor and C. setodaotylus but is
easily distinguished from these species by the presence of a row of comb
spines on the outer ramus of the second uropod of the male and by other
differences noted in the accompanying key. The range of this species
extends from southcentral Maryland south and southwest along the Piedmont
and western margin of the Coastal Plain to southcentral Virginia (Fig.
19). C. shoemdkev-i is an inhabitant of temporary pools and ponds (often
with grassy bottoms), springs, small streams, and bogs. Sexually mature
males, 5.5 to 9.5 mm; sexually mature females, 9.0 to 13.5 mm. Ovigerous
females occur from February to May, followed by immatures during the
summer. Life cycle of about one year.
Figure 20. -- Distribution of species of Crangonyx in North America.
47
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Genus Synurella Wrzesniowski, 1877
This genus is widespread in the Holarctic region but is represented by a
greater number of species in Europe and Asia than in North America. Only
four of approximately 18 described species occur in North America and
only three of these are found in the contiguous United States; the other
species (Synurella johanseni Shoemaker, 1920) is known from Alaska.
Although several of the European species are represented in subterranean
waters, none of the North American forms are known to be subterranean or
troglobitic.
Synurella bears a superficial resemblance to Crangonyx but can be dis-
tinguished easily by the short, uni-ramous third uropod and the rather
narrow, deeply cleft telson. Juveniles of the three species of the
United States undergo a peculiar developmental phenomenon in which the
gnathopodal propods bear a large, distal spine or process. This process
decreases with increase in size and disappears at maturity.
Key to the North American Species of SynuTella (excluding Alaska)
1 Palmar margins of gnathopodal propods distinctly concave (Fig. 21a) ;
uronites fused; mature males larger than mature females; sexually
mature specimens from 7.5 to 19.0 mm: S. dentata
Palmar margins of gnathopodal propods straight to only slightly
concave (Fig. 21b); uronites fused or not; mature males smaller
than mature females; sexually mature specimens from 5.0 to 14.0 mm
2
2(1) Uronites fused; sexually mature specimens from 6.0 to 14.0 mm:
S. bifurca
Uronites not fused (free); sexually mature specimens from 5.0 to
12.0 mm: S. ohambeplaini
Annotated List of the Species
1. Synurella bifuraa (Hay, 1882)
Type Locality: Rivulet following into the Noxubee River at Macon, Noxubee
Co., Mississippi.
This species is principally an inhabitant of the Mississippian embayment
region and is distributed from southeastern Missouri and western Tennes-
see through eastern and southern Arkansas into Louisiana, west into
southeastern Texas and east through Mississippi into western Alabama
(Fig. 22). S. bifuraa is found in small streams, temporary ponds and
pools, springs, seeps, ditches, and sloughs. Ovigerous females occur
from December to May or June; immatures only in late summer and fall.
Life cycle of one year. Sexually mature males, 6.0 to 10.5 mm; sexually
mature females, 7.5 to 14.0 mm. Newly hatched young are 1.5 mm. Larger
females produce from 140 to 215 eggs per brood.
48
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2. Synwella ehambevlaini (Ellis, 1941)
Type Locality: Pond on the Richmond Plantation, 2.4 miles south of
Cordesville, Berkeley Co., South Carolina.
This species is distributed from Maryland southward along the Atlantic
Coastal Plain to South Carolina (Fig. 22). It is an inhabitant of small
streams, bogs, ponds, and ditches and is often associated with Cvangonyx
spp. Ovigerous females occur in winter and spring; immatures only during
the late summer and fall. Life cycle of one year. Sexually mature males,
5.0 to 8.5 mm; sexually mature females, 6.0 to 12.0 mm (the majority
being 7.0 to 10.0 mm). Sexual maturity is reached at a slightly smaller
size in the southern part (Carolinas) of the range. Ovigerous females
brood up to 65 eggs per clutch and newly hatched young are 1.5 mm.
a
Figure 21. -- Structure of Synurella: a, 2nd gnathopodal propod of
male of S. dentata; b, 2nd gnathopodal propod of male of 5. bifurea.
49
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S. bifurco
S. chamberlaini
S. dentate
Figure 22. -- Distribution of species of Synurella in North
America (excluding Alaska).
50
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3. Synweella dentata Hubricht, 1943
Type Locality: Small spring in a barnyard near an old mansion, 2.9 miles
south-southwest of Jimtown, Fayette Co., Kentucky.
This species is easily distinguished from the above by the males being
larger than the females at sexual maturity and the concave palmar margins
of the gnathopodal propods. 5. dentata inhabits springs and small streams
(mostly spring-fed) and ranges from southeastern Indiana to southern Ohio,
south into Kentucky and as far south as northcentral Tennessee (Fig. 22).
This species is very common in springs and spring runs of the Bluegrass
region of northcentral Kentucky where it is commonly associated with
Cvangonyx setodactylus and less frequently with Crangonyx anomalus and
Cvangonyx sp. (graoilis group). Sexually mature males, 10.0 to 19.0 mm
(most between 11.0 and 13.0 mm); sexually mature females, 7.5 to 15.0 mm
(average is 9.0 to 11.0 mm); newly hatched young = 1.5 mm. Ovigerous
females produce up to 125 eggs per brood and occur in late fall, winter
and early spring. Immatures are found throughout the year with seasonal
peaks.
51
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Figure 23. -- Structure of Apoerangonyx (based on Holsinger, 1969b);
a, 2nd gnathopodal propod of male of A. araeus; b, 2nd gnathopodal
propod of male of A. subtilis; cs dactyls and distal ends of propods
of pereopods 6 and 7 of A. parvus; d, dactyls and distal ends of
propods of pereopods of A. ephemerus.
52
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Genus Apoarangonyx Stebbing, 1899
The genus Apoorangonyx is composed o£ six described and seven unde-
scribed small, cryptic subterranean species, most of which have
very narrowly defined ranges. Five of the six described species
are keyed out below. The undescribed species are known from caves
in the Appalachian region (three from West Virginia, two from
Alabama, one from Tennessee and one from Georgia) and are apparently
quite rare and highly insular in distribution. Two of the described
species (i.e., A. ephemeras and A. parvus~), along with the three
undescribed species from West Virginia, have several important char-
acters in common with Appalachian species of Stygoneotes and may be
reassigned to this genus in a future revision by the writer. Since
two recent papers by Holsinger (1969a, 1969b) treated the distribution
of the species of this genus in detail, range maps will not be repeated.
Key to the Species of Apoorangonyx
A. luoifugus is not included for reasons given below and elsewhere
(Holsinger, 1969b).
1 Propod of gnathopod 2 larger than 1 (especially in mature males);
posterior margin of gnathopodal propod 1 with marginal setae
2
Propod of gnathopod 2 about equal in size to propod 1 in both
sexes; posterior margin of gnathopodal propod 1 without
setae 4
2(1) Palmar margin of gnathopodal propod 2 of male with deep exca-
vation (Fig. 23a); distoposterior corners of abdominal side
plates of female well developed, subacute; telson and uropod 1
of male slender and elongate: A. avaeus
Palmar margin of gnathopodal propod 2 of male without deep ex-
cavation; distoposterior corners of abdominal side plates of
female poorly developed, rounded; telson and uropod 1 of male
normal, not elongate 3
3(2) Palmar margin of gnathopodal propod 2 of male with 2 median
processes (Fig. 23b); lateral sternal processes bifurcate;
lateral spines absent on inner ramus of uropod 1: .4. subtil-ls
Palmar margin of gnathopodal propod 2 of male without median
processes; lateral sternal processes simple (not bifurcate);
lateral spines present on inner ramus of uropod 1: A. novtoni,
4(1) Distal ends of pereopodal propods 5-7 with 1 very long seta each
(Fig. 23c); apical margin of telson with 9 to 10 spines; sexu-
ally mature females up to 2.7 mm long: A, parvus
Distal ends of pereopodal propods 5-7 without elongate setae
(Fig. 23d); apical margin of telson with 6-8 spines; sexually
mature females up to 5.0 mm long;, A. ephemerus
53
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Annotated List of the Species
1. Apoarangonyx araeus Holsinger, 1969b
Type Locality: Seep, 1.0 miles south of Crittenden, Nansemond Co., Vir-
ginia.
A very unique, interstitial species that inhabits groundwater seeps and
small springs in the Tidewater area of southeastern Virginia and extends
from Matthews County south to Norfolk Co. (now Norfolk City) and south-
westward to Nansemond county. Sexually mature males reach 7.0 mm; sex-
ually mature females, 3.5 to 5.5 mm. Newly hatched young = 1.0 mm.
Ovigerous females in late winter and early spring and perhaps throughout
the year but samples from summer and fall are not available.
2. Apoavangonyx ephemeTus Holsinger; 1969b
Type Locality: Tawneys Cave, Giles Co., Virginia.
This species is known from mud-bottom, drip pools in two caves in the
Sinking Creek valley of Giles Co., Virginia. Sexually mature males,
3.4 mm; sexually mature females, 3.5 to 5.0 mm.
3. Apoarangonyx lua-ifugus (Hay. 1882)
Type Locality: Well in Abingdon, Knox Co., Illinois.
Since type material does not exist and attempts to collect "topotypes"
have been unsuccessful, the status of this species remains vague. A.
lucifugus may be conspecific with A. subtilis (see Holsinger, 1969b
for further comments).
4. Apoarangonyx novtoni Holsinger, 1969b
Type Locality: Ingram Cave, Clay Co., Tennessee.
This species is known only from the type locality, where it was collected
from a seepage pool. Largest males, 3.85 mm; largest females (sexually
mature), 3.5 mm. Other biological data are not available.
5. Apoarangonyx parvus Holsinger, 1969b
Type Locality: Crawford Cave No. 2, Randolph Co., West Virginia.
This tiny species is known authentically only from the type locality
where it was found in two mud-bottom drip and seep pools. A second
record (Cassell-Windy Cave, Pocahontas Co., West Virginia) given by
Holsinger (1969b) was based on a single specimen, but on further exami-
nation appears to represent another species. Largest males, 2.5 mm;
largest females (sexually mature), 2.7 mm. This is the smallest de-
scribed species of Gammaridae from North America. Two of the unde-
scribed species of Apoovangonyx from West Virginia reach sexual maturity
at an even smaller size, however.
6. ApocTcmgonyx subtilis Hubricht, 1943
Type Locality: Small seep, 5.0 miles southwest of Pomona, Jackson Co.,
Illinois.
This is the widest ranging species of the genus and extends from Adams
Co., Illinois south-southeastward to Union Co., Illinois and west to
St. Genevieve Co., Missouri. This species is known from both seeps and
cave pools. Ovigerous females are available from April collections and
sexually mature specimens have been observed in collections from
54
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October and November. Breeding may continue the year around but only a
few females are ovigerous at a given time. Sexually mature males, 4.0
to 5.0 mm; sexually mature females, 3.0 to 4.5 mm.
Genus Stygoneetes W. P. Hay, 1903
Synonym = Synpleonia Greaser, 1934.
The genus Stygoneotes contains 29 described and nine undescribed sub-
terranean species, which occupy groundwater habitats from Vermont and
New York south and southwestward to Texas and Oklahoma. The genus was
treated in detail in a recent monographic revision by Holsinger (1967),
and many additional data on the group can be found there. All but one
of the undescribed species have been collected since the generic re-
vision in 1967 and will be described in a future paper by the writer
(in preparation). Distributional maps for the species can be found in
Holsinger (1967, 1969a) and are not included in the manual. The range
maps published by the writer in 1969 were for central Appalachian
species and reflect most of the data acquired on the genus subsequent
to the 1967 revision.
Key to the Species Groups of Stygonectes
The following key to species groups; keys to individual species with-
in these groups can be found in Holsinger (1967) and will not be
repeated here.
1 Propod of gnathopod 1 often stouter but otherwise about equal in
size to 2; pereopod 6 and 7 about equal in length; sexually
mature males typically smaller than sexually mature females.. 2
Propod of gnathopod 1 stouter and usually larger than 2; pereopod
7 a little longer than 6 (excepting one rare species); sexually
mature males larger than sexually mature females 5
2(1) Posterior margin of gnathopodal propod 1 rather short, without
setae (excepting one rare species); posterior angle of gnath-
opodal propod 1 with 2 to 6 large, unequal but typically curved
spines on outside (Fig. 24a); posterior margins of abdominal
side plates convex (Fig. 24b) 3
Posterior margin of gnathopodal propod 1 with 3 to 5 groups of
setae; posterior angle of gnathopodal propod 1 with 1 large and
usually straight spine on outside (Fig. 24e); posterior margins
of abdominal side plates weakly convex to relatively straight
(Fig. 24£) 4
55
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Figure 24. -- Structure of Stygoneotes: a, 1st gnathopodal propod
of S. emcncginatus; b, abdominal side plates of S. emapginatusj c,
lower lip of S. sp-inatus (based on Holsinger, 1967); d, telson of
S. spinatus (based on Holsinger, 1967); e, 1st gnathopodal propod
of S. flagellatus; f, abdominal side plates of S. longipes; g,
basis of pereopod 7 of S. emarginatus.
56
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3(2) Inner lobes of lower lip vestigial or absent (Fig. 24c); disto-
posterior lobes of pereopod bases rather well defined;
posterior margins of abdominal side plates with up to 10
setae; telson without lateral spines, apical margin convex
(Fig. 24d); spinatus group (S. spinatus)
Inner lobes of lower lip not vestigial but sometimes small;
distoposterior lobes of pereopod bases usually rather poorly-
defined or nearly absent (Fig. 24g); posterior margins of
abdominal side plates with up to 6 (but often fewer than 6)
setae; telson with lateral spines and without excavation in
apical margin, or without lateral spines and with or without
shallow excavation in apical margin emarginatus group
4(1) Coxal plate of pereopod 4 enlarged (Fig. 25a); bases of pereopods
5-7 broadly expanded posteriorly, distoposterior lobes broad
and well defined; apical margin of telson entire or with
shallow excavation; telson without lateral spines
hadenoeous group
Coxal plate of pereopod 4 not enlarged (Fig. 25c); bases of
pereopods 5-7 not greatly expanded posteriorly, distoposterior
lobes rather small or poorly defined; telson rather long, with
or without lateral spines, apical margin without excavation
(Fig. 25b) flagellatus group
5(1) Propod of gnathopod 1 up to twice the size of propod of gnathopod
2, propod palmar margin of sexually mature males with a
prominent distal notch or shallow excavation (Fig. 25d); basis
of pereopod 7 of larger males with a prominent ventrally
produced distoanterior lobe (Fig. 25f); telson with lateral
spines pizzinii group
Propod of gnathopod 1 larger but not twice as large as propod of
gnathopod 2; propod palmar margin of sexually mature males
without distal notch or excavation; larger males without a
prominent distoanterior lobe on pereopod 7 (Fig. 25e); telson
with lateral spines in only 2 species tennis group
57
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Figure 25. -- Structure of Stygoneates: a, coxal plate of S.
hadenoeeus; b, telson of female of S. flagellatus; c, coxal
plate of S. flagellatus (based on Holsinger- 1966); d, 1st
gnathopodal propod of male of S. indentatus; e., basis of
pereopod 7 of S. alabamensis; f, basis of pereopod 7 of male
of S. indentatus.
58
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Annotated List of the Species
Species are arranged within species groups in the same order as they
were presented in Holsinger (1967). Individual species are treated
in detail only where new data have been obtained since the 1967
revision.
Emarginatus group
1. Stygoneotes emavg-inatus (Hubricht, 1943)
Type Locality: Organ Cave section of Greenbrier Caverns, Greenbrier Co.,
West Virginia.
This species occupies small cave streams and sometimes pools. In the
caves of the Greenbrier valley of West Virginia, it is often found in
company with Stygoneotes spinatus, Gammarus minus and the isopod Asellus
hols-ingeri (see Culver, 1970 for further details on this ecological
relationship). The range extends from western Maryland (Garrett County)
south-southwestward through the Appalachian valley and along the eastern
margin of the Appalachian Plateau to Monroe Co., West Virginia. Sexually
mature males, 9.0 to 10.5 mm; sexually mature females, 9.0 to 14.0 mm.
Sexually mature females have been observed in spring and summer and
ovigerous females have been collected in August. However, adult-sized
animals have been found the year around, suggesting that breeding may be
continuous.
2. Stygoneotes mundus Holsinger, 1967
Type Locality: Witheros Cave, Bath Co., Virginia.
This species was described from only three specimens, none of which were
completely mature. For reasons given elsewhere (Holsinger, 1969a), which
were based on examination of material subsequent to 1967, the writer con-
siders this form to be a probable subspecies of Stygoneotes emavginatus.
3. Stygoneotes morrisoni Holsinger, 1967
Type Locality: Witheros Cave, Bath Co., Virginia.
Although this species was originally described from a series of specimens
collected from a single cave (Witheros Cave), it has subsequently been
found farther to the north in Pendleton Co., West Virginia and possibly in
Hardy Co., West Virginia. The latter, however, may represent a closely
related species or subspecies (Holsinger, 1969a). In the type locality,
Stygoneotes morrisoni occurs syntopically with Stygoneotes mundus
(s. str.), where it is apparently much more abundant. Largest male, 6.0
mm; sexually mature females, 6.0 to 8.0 mm. Ovigerous females have been
collected in the early spring but little else is known about the biology
of this species.
4. Stygoneotes ooopevi, Holsinger, 1967
Type Locality: Silers Cave, Berkeley Co., West Virginia.
This species is known only from two males, the largest of which is 6.0 mm.
Morphologically, Stygoneotes ooopevi shows rather close affinity with sev-
eral species of Stygobvomus and may be reassigned to this genus in the
future. The species inhabits small, mud-bottom seep pools in the type
locality.
59
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5. Stygoneotes stellmacki. Holsinger, 1967
Type Locality: Millers Cave, Centre Co., Pennsylvania.
This rather unique species was originally described from a single male
(14.25 mm) but subsequent collecting has resulted in the discovery of
two females (the largest being 15.40 mm). Stygoneotes stellmaoki
occurs in a shallow, mud-bottom pool in the type locality but nothing
else is known about its ecology.
6. Stygonectes gvaoilipes Holsinger, 1967
Type Locality: Skyline Caverns, Warren Co., Virginia.
This rather large, distinct species ranges from southern Franklin Co.,
Pennsylvania south-southwestward through the Shenandoah Valley to
Rockingham Co., Virginia. It is an inhabitant of cave pools and
occasionally small cave streams. Sexually mature males, 9.0 to 10.5 mm;
sexually mature females, 10.0 to 18.0 mm. Adult specimens are found in
various populations the year around but ovigerous females are currently
known only from a January sample.
7. Stygoneotes oonr>adi Holsinger, 1967
Type Locality: Butler-Sinking Creek Cave, Bath Co., Virginia.
This small cavernicolous species, closely related to Stygoneot.es
gra.o-i1i.pes, is known only from its type locality. Although the species
was originally described from females (largest, 8.25 mm), two small
males were recently obtained from the type locality and are morpholo-
gically similar to the females. Stygoneotes oonradi is found in gravels
in the cave stream where it is extremely rare and is associated with
snails (J?antigens} and isopods (Asellus}, the last two groups being much
more common.
Spinatus group
8. Stygoneotes spinatus Holsinger, 1967
Type Locality: Court Street Cave, Greenbrier Co., West Virginia.
This species inhabits caves of the Greenbrier valley and extends from
central Pocahontas Co. south to central Monroe Co., West Virginia. At
least one subspecies occurs in the caves around Greenville, West Virginia
(westcentral Monroe County) . Stygoneotes spinatus is found in the
gravels of small streams and in small cave pools; it is often associated
with Stygoneotes emarginatus, Gammarus minus, and Asellus holsingeri (see
above and also Culver, 1970). Sexually mature males, 3.5 to 5.5 mm; sex-
ually mature females, 4.3 to 7.5 mm. Adults have been observed during
every season of the year and ovigerous females have been taken during the
spring, summer, and fall. Breeding apparently takes place year round,
with only a small percentage of the mature females producing young at a
given time.
Pizzini group
9. Stygoneotes pizzinii (Shoemaker, 1938)
Type Locality: Wetzels Spring, Glover Archbold Parkway, Washington, D. C.
This species is recorded from a series of groundwater habitats (caves,
springs, seeps and wells) in the Piedmont and is distributed from Fairfax
60
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Co., Virginia northeastward to Chester and Lancaster counties, Pennsyl-
vania. The range is discontinuous between Howard Co., Maryland and
Lancaster Co., Pennsylvania. Sexually mature males, 8.0 to 18.75 mm;
sexually mature females, 7.5 to 15.75 mm. In general, animals reach
sexual maturity at a larger size and attain a greater length in the
Reftons Cave (Lancaster Co., Pennsylvania) population than anywhere
else in the range (see HolsingerP 1967 for a possible explanation).
Sexually mature adults, ovigerous females and juveniles are found the
year around indicating that reproduction is continuous in this species.
10. Stygonectes indentatus Holsinger, 1967
Type Locality: Outlet of drain, 3 miles northwest of Suffolk, Nansemond
Co., Virginia.
An interstitial species, somewhat smaller than, but closely related to,
Stygoneotes pizzinii. This species is known from two drains in Nanse-
mond Co., Virginia and one seep in adjoining Isle of Wight Co., Vir-
ginia. Sexually mature males, 7.5 to 9.75 mm; sexually mature females,
6.0 to 7.5 mm. Nothing is known about the life cycle except that
ovigerous females were observed in a January collection.
Tenu-is group
11. Stygoneotes tennis s. lat.--two subspecies are recognized as
follows:
a) S. t. tennis (Smith, 1874)
Type Locality: Wells at Middletown, Middlesex Co., Connecticut.
This subspecies is disjunctly distributed in groundwater habitats (wells
and seeps) from central Connecticut southwestward to the Maryland pen-
insula.
b) S. t. potomaous Holsinger, 1967
Type Locality: Bog in Burleith Woods, Georgetown, Washington, D. C.
This subspecies differs slightly but consistently from S. t. tennis in
lacking coxal gills on pereopod 7 (both sexes) and sternal processes on
the pleonite of the male. It is rather common in groundwater habitats
(especially in seeps and small wet-weather bogs) in the vicinity of
Washington, D. C. The range extends from central Maryland (west of the
Chesapeake Bay) westward to the Blue Ridge Mountains and south to the
vicinity of Richmond, Virginia). The biology of S. tennis s. lat. can
be summarized as follows: Sexually mature males, 9.0 to 16.5 mm (but
rarely larger than 12.0 mm); sexually mature females, 5.5 to 9.75 mm.
Ovigerous females have been found in winter, spring and summer collec-
tions and mature adults and juveniles occur in collections the year
around. Reproduction may be continuous.
12. Stygoneotes allegheniensis Holsinger- 1967
Type Locality: Spring, Ilion, Herkimer Co., New York.
A wide-ranging, somewhat variable species found in a variety of sub-
terranean habitats (i.e., especially caves, wells, and springs) of the
Appalachian Plateau of central and southern New York, westcentral Penn-
sylvania and western Maryland, the Valley and Ridge of central Pennsyl-
vania, and the Piedmont of southeastern Pennsylvania. Sexually mature
61
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males, 8.0 to 13.5 mm; sexually mature females, 5.25 to 13.0 mm. Ovig-
erous females from March through November and possibly all year around.
This species is a common cavernicole in the small pools of the caves
of Albany and Schoharie counties, New York.
13. Stygoneotes nayi (Hubricht and Mackin, 1940)
Type Locality: Small spring, south end of National Zoological Park,
Washington, D. C.
This species is known only from its type locality where it occurs
synotopically with S. tennis potomaaus. Largest males, 9.75; largest
females, 10.0 mm.
14. Stygoneotes aldbcmensis s. lat.--two subspecies as follows:
a) S. a. aldbcmensis (Stout, 1911)
Type Locality: Well, 1 mile east of P.O., Auburn, Lee Co., Alabama.
This wide ranging subspecies is distributed from southcentral Alabama
westward to eastcentral Mississippi and then northwestward to south-
western Tennessee, then westward across northern Arkansas to eastern
Oklahoma and north to central Missouri. The species is somewhat vari-
able morphologically as well as ecologically and occupies a variety of
groundwater biotopes, including seeps, springs, wells, and caves.
b) S. a. oooidentdlis Holsinger, 1967
Type Locality: seeps, 2.3 miles south of Fittstown, Pontotoc Co.,
Oklahoma.
This subspecies is sparsely distributed in groundwater outlets (seeps
and springs) from Tulsa Co., Oklahoma southward through the Arbuckle
Mountains to Dallas Co., Texas and possibly eastward to Union Co.,
Louisiana. The biology of S. aldbcmensis s. lat. can be summarized as
follows: Sexually mature males, 9.0 to 13.5 mm; sexually mature
females, 6.0 to 13.0 (but usually not exceeding 10.0 mm). Ovigerous
females have been taken in the spring and fall but sexually mature
specimens are known from all seasons of the year.
15. Stygoneotes montanus Holsinger, 1967
Type Locality: Springs, Rich Mtn., Rich Mtn. Station, Polk Co.,
Arkansas.
This species is known only from its type locality and virtually nothing
is known about its biology. There is some evidence to indicate that
this species may be a peripherally isolated, highly aberrant form of
Stygoneotes aldbcmensis and not a distinct species as originally in-
dicated by Holsinger (1967). The true status of this species must
await further study, however.
16. Stygoneotes elatus Holsinger, 1967
Type Locality: Seep, 0.2 mile east of The Lodge, Magazine Mtn., Logan
Co., Arkansas.
This species is known only from its type locality, where it is appar-
ently uncommon. A number of other seeps on Magazine Mountain contain
populations of Stygoneotes aldbcmensis but not Stygoneotes elatus.
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17. Stygoneotes barr-i Holsinger, 1967
Type Locality: Seep, 0.5 mile east of Greenville, Wayne Co., Missouri.
Outside of the type locality: this species is known only from an
intermittent stream in Madison Co., Missouri. Sexually mature males,
10.5 to 12.75 mm; sexually mature females, 6.5 to 8.5mm. Collections
are available only from April, at which time ovigerous females were ob-
served.
18. Stygoneotes baloonis Hubricht, 1943
Type Locality: Boyetts Cave, Hays Co., Texas.
Outside of the type locality, this species is known only from Irelands
Cave (Travis County) which is situated 25 miles north-northeast of the
former. Largest males, 16.0 mm; largest females, 9.75 mm to 12.50 mm.
Ovigerous females are unknown to date; most of the specimens collected
have been males.
19. Stygoneotes bifuroatus Holsinger, 1967
Type Locality: Gorman Cave, San Saba Co., Texas.
This species ranges from Kendall County north-northeastward through Travis
County to Coryell County and then westward through Larapasas County to San
Saba County. Stygoneotes bifuvoatus usually occurs in cave pools and is
sometimes found syntopically with Stygoneotes Tusselli (see below). Sex-
ually mature males, 13.0 to 19.0 mm; sexually mature females, 11.0 to
14.0 mm. Newly hatched young = ca. 2.0 mm. Mature specimens have been
collected during spring, summer and fall but ovigerous females are
presently known only from collections made in the spring and summer.
20. Stygoneotes vusselli Holsinger, 1967
Type Locality: Tippits Cave, Coryell Co., Texas.
This highly variable cavernicolous species is recorded from seven counties
in the eastern and eastcentral portion of the Edwards Plateau region of
Texas. There are geographic clusters of populations and several signifi-
cant gaps in the range, and this, coupled with the variable morphology of
the species, strongly indicates a polytypic species or perhaps a species
complex (Holsinger, 1967). Even though a number of collections have been
made since 1967, the problem is still far from being resolved. S.
Yusselli, inhabits shallow cave pools and small streams and sometimes
occurs syntopically with S. bifiwoatus and rarely with S. baloonis and
S. dejeotus. Sexually mature males, 7.5 to 10.0 mm; sexually mature
females, 5.5 to 14.0 mm. Newly hatched young = ca. 2.0 mm. Sexually ma-
ture specimens and juveniles have been collected during all seasons of the
year and ovigerous females are known from winter, spring and summer. Like
many other cavernicolous amphipod species, S. russelli probably breeds the
year around.
21. Stygoneotes reddelli Holsinger, 1966
Type Locality: Whiteface Cave, San Saba Co., Texas.
This species is known only from five females collected from the type
locality. Larger females, apparently sexually mature, are 12.0 to
13.50 mm.
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22. Stygonectes olantoni (Greaser, 1934)
Type Locality: Well on Clanton Farm, 4 miles southeast of Ottawa,
Franklin Co., Kansas.
This large subterranean species is known from groundwater habitats
(mostly wells) and is disjunctly distributed from Butler Co., Kansas,
northeastward to Franklin Co., Kansas and Cass Co., Missouri and then
southeastward to Camden Co., Missouri. Sexually mature males, 18.0
to 19.5 mm; sexually mature females, 14.5 to 18.0 mm. Ovigerous fe-
males are unknown to date and very little is known about the biology
of this species.
23. Stygonectes ozarkensis Holsinger, 1967
Type Locality: Marvel Cave, Stone Co., Missouri.
This is a somewhat variable species, apparently closely related to
Stygoneotes clantoni, but primarily restricted to cave streams of the
southwestern corner of the Ozark Plateau region (southwestern Missouri
northwestern Arkansas, and northeastern Oklahoma). Since 1967, this
species has been recorded from Tumbling Creek Cave, Taney Co., Smittle
Cave, Wright Co., and Fantastic Caverns, Greene Co., Missouri; Cave
Springs Cave, Benton Co., Arkansas; and Three Forks Cave, Adair Co.,
Oklahoma. The Greene and Wright County populations show possible
evidence of intergrading with Stygonectes olantoni but this needs fur-
ther study. Sexually mature males, 15.0 to 18.5 mm; sexually mature
females, 13.0 to 16.5 mm. Ovigerous females have not been collected and
little is known about the biology of this species.
24. Stygonectes bowmani Holsinger, 1967
Type Locality: Seep at Girl Scout Camp, 3.2 miles south of Locust Grove,
Mayes Co., Oklahoma.
This rather small, poorly known species is based on 8 females and 8
juveniles collected from the type locality. Sexually mature females,
6.0 to 7.0 mm. Male unknown. One of the females in the type series
(May collection) was ovigerous.
Flagellatus group
25. Stygoneotes flagellatus (Benedict, 1896)
Type Locality: Artesian well at San Marcos, Hays Co,, Texas,
This rare species is known only from the type locality and nearby Ezells
Cave. Sexually mature males, 10.5 to 12.0 mm; sexually mature females
7.5 (?) to 14.0 mm. Although collections are available from the months
of April, May, June, and October, few specimens have been taken and
ovigerous females are still unknown.
26. Stygoneotes long-ipes Holsinger, 1966
Type Locality: Cave Without-A-Name (Century Caverns), Kendall Co., Texas.
This species is authentically recorded only from the type locality,
although a single, partially broken specimen is known from Bad Weather
Pit Cave in nearby Comal County and appears to be conspecific. Sexually
mature males, 9.0 to 12.0 (?) mm; sexually mature females, 10.5 to 12.0
mm. A single ovigerous female is known from a collection made in May
from a stream in the type locality.
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27. Stygoneotes peoki Holsinger, 1967
Type Locality: Spring in Landa Park (Comal Springs), New Braunfels, Comal
Co., Texas.
This rare species is known only from two females, both of which are from
the type locality. The larger female (near sexual maturity) = 10.5 mm.
28. Stygoneotes dejectus Holsinger, 1967
Type Locality: Cascade Cave, Kendall Co., Texas.
This species is known only from two females collected from a pool in the
type locality. The larger female = 8.25 mm.
Eadenoeous group
29. Stygoneotes hadenoeous Holsinger, 1966
Type Locality: Devils Sinkhole Cave, Edwards Co., Texas.
This species is known only from its type locality where it is rather com-
mon in pools with bat guano and the cirolanid isopod Civolanides texens-is.
Sexually mature males, 9.0 to 10.0 mm; sexually mature females, 10.0 to
12.0 mm. Although collections have been made during March, June, and
October, ovigerous females are still unknown.
Genus Stygobromus Cope, 1872
The subterranean genus StygdbTomus is widely distributed in the ground-
waters of the United States, with species concentrations in the cave
regions of the Appalachians, Interior Low plateaus, Ozarks, and far west.
As presently defined, the genus contains 10 described and approximately
50 undescribed species in North America and one poorly known species from
Siberia. The latter, S. pusillus (Martynov, 1930), was described from
Telelzkoye Lake in 1930 but recent attempts to locate this material for
further study have not been successful, and the status of this species
remains vague. A fairly recent redescription of this genus was given by
Shoemaker (1942a).
Key to the North American Species of Stygobrorms
1 Apical margin of telson entire, not distinctly cleft 2
Apical margin of telson distinctly cleft 5
2(1) Gnathopodal propod 2 of male greatly enlarged, palmar margin with
a distinct notch (Fig. 26a); posterior junction of dactyl and
propod of pereopods 6 and 7 with several long, thread-like setae
(Fig. 26b); basis of pereopod 7 broad, distoposterior corner
subquadrate: S. heteropodus
Gnathopodal propod 2 of male not greatly enlarged, palmar margin
without a notch; setae at junction of dactyl and propod of
pereopods 6 and 7 not elongate or thread-like; basis of pereopod
7 not so broad, distoposterior corner rounded 3
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Figure 26. -- Structure of Stygobromus: a, 2nd gnathopodal propod of
male of S. heteropodus (based on Hubricht, 1943); b, dactyls of pereopods
6 and 7 of S. heteropodus; c, 1st gnathopodal propod of S. spinosus (based
on Hubricht and Mackin, 1940); d, telson of S. exilis; e, telson of S.
onondagaensis; f, basis of pereopod 7 of S. hubbsi (based on Shoemaker-
1942b); g, uropod 3 of 5. vitreus; h, uropod 3 of 5. smithi; i, 2nd
gnathopodal propod of S. smithi (modified from Hubricht, 1943).
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3(2) Pereopods 6 and 7 and gnathopodal propods 1 and 2 about equal in
length and size, respectively; posterior margin of gnathopodal
propod 1 short, without setae (Fig. 26c): S. spinosus
Gnathopodal propod 2 larger than 1; pereopod 6 a little longer
than 7; posterior margin of gnathopodal propod 1 lined with a
row of setae 4
4(3) Palmar margin of female gnathopodal propod 2 oblique, posterior
margin about 1/3 as long as propod; dactyls of pereopods 6 and
7 up to 1/3 as long as corresponding propods; telson short and
rather broad, armed with 10 to 20 comparatively short apical
spines (Fig. 26e): S. onondagaensis
Palmar margin of female gnathopodal propod 2 only slightly oblique,
posterior margin at least 1/2 as long as propod; dactyls of
pereopods 6 and 7 1/3 to 1/2 as long as corresponding propods;
telson proportionately longer and more narrow, armed with 10 to
20 comparatively long spines (Fig. 26d): S. exilis
5 (1) Sternal processes absent 6
Sternal processes present 7
6(5) Gnathopodal propod 2 long and narrow, palmar margin long and
oblique and about 3/4 as long as propod; bases of pereopods 5,
6, and 7 rather long and narrow, posterior margins not expanded
(Fig. 26f): S. hubbsi
Gnathopodal propod 2 not especially long or narrow, palmar margin
oblique but only about 2/3 as long as propod; bases of
pereopods 5, 6, and 7 with slightly convex posterior margins:
S. putealis
7(5) Gnathopodal propod 1 nearly as large as 2, with long, oblique
palmar margin continuous with posterior margin; peduncle of
uropod 3 with usually 1 prominent spine (sometimes absent in
male): S. maek-ini
Gnathopodal propod 1 distinctly smaller than 2, palmar margin not
so oblique and forming definite angle (defining angle) at junc-
tion with posterior margin; peduncle of uropod 3 without spines
(although 1 or 2 stiff setae may be present) 8
8(7) Defining angle of gnathopodal propod 2 very distinct (Fig. 26i);
outer ramus of uropod 3 tiny and with 1 spine (Fig. 26h); telson
with 16 to 20 apical spines: 5. smithi
Defining angle of gnathopodal propod 2 not very distinct; outer
ramus of uropod 3 larger and with 2 to 3 spines (Fig. 26g);
telson with 8 to 15 apical spines 9
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9(8) Gnathopodal propod 2 nearly twice the size of 1; posterior margin
of gnathopodal propod 1 with a row of 5 to 10 setae; median
sternal and pleonite sternal processes present (the latter
occasionally absent in the male)'. S. vitreus
Gnathopodal propod 2 only a little larger than 1; posterior mar-
gin of gnathopodal propod 1 nearly devoid of setae; median
sternal and pleonite sternal processes absent: 5. iowae
Annotated List of the Species
1. Stygobromus exitis Hubricht, 1943
Type Locality: Mammoth Onyx Cave, Hart Co., Kentucky.
The range of this predominately cavernicolous species extends from
southcentral Kentucky southward through central Tennessee and possibly
into Alabama to as far south as Clarke County (Fig. 27). There is con-
siderable variation in this species, however, and the populations from
central Tennessee and Alabama may constitute one or two separate
(undescribed) species or subspecies. A more accurate delimitation of
the range must await further study. S. ex-ills is a common inhabitant
of mud-bottom drip and seep pools but is occasionally found in small
streams; it is also known from one surface seep in the Mammoth Cave
area. This species occurs rarely with Stygobromus vitreus (in the
Mammoth Cave area) and frequently with Crangonyx spp. (often with
Crangonyx paakardi~). Sexually mature males, 4.0 to 5.5 mm; sexually
mature females, 3.5 to 8.5 mm (but usually 4.5 to 6.5 mm). Newly
hatched young = 1.3 to 1.4 mm. Ovigerous females have been observed
in spring, summer, and fall and mature specimens the year around. The
brood size varies from two to nine eggs depending on the size of the
female. Between eight and ten distinct, undescribed species, all of
which share morphological affinities with S. exitis., occur in caves of
the Interior Low Plateau region from northern Alabama to central
Kentucky.
2. Stygobromus heteropodus Hubricht, 1943
Type Locality: Small spring in the main valley, Pickle Springs, St.
Genevieve Co., Missouri.
This rather unique species is known only from its type locality
(Fig. 29). Largest male, 7.0 mm; largest female, 6.5 mm. Virtually
nothing is known about the biology of this species except that sexual
dimorphism is quite pronounced. A closely related species (undescribed)
is known from seeps in Edmonson and Grayson counties, Kentucky.
3. Stygobromus hubbsi Shoemaker- 1942b
Type Locality: Malheur Cave, Harney Co., Oregon.
This species is presently known only from pools in the back of a lava
tube cave (the type locality) (Fig. 29), where it was collected in
company with blind, white planarians (Kerikia rhynahida Hyman). Largest
males, 5.5 mm; largest females, 6.5 mm. It is interesting to note that,
in addition to S. hubbsi, 11 other species (all undescribed) of
Stygobromus have been collected from a variety of groundwater habitats
(caves, springs, wells, and the depths of a lake) scattered throughout
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the far western United States (west of the continental divide). All of
these species are morphologically closely related to S. hubbsi and will
be described in a subsequent paper. Even a twelfth undescribed species
has been collected from this region but it is not closely allied
morphologically with S. hubbsi and apparently belongs to another species
group.
S. exilis
S. mackini
S. onondagaensis
Figure 27. -- Distribution of species of Stygobromus in North America.
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S. 10 woe
S. puteolis
S. vitreus s. lat.
Figure 28. -- Distribution of species of Stygobromus in North America.
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4. Stygobromus -iowae Hubricht, 1943
Type Locality: Springs, 0.7 mile north of Fayette, Fayette Co., Iowa.
This subterranean species is presently known from a spring and two
caves in northeastern Iowa and from a mine in extreme northwestern
Illinois (Fig. 28). Sexually mature males, 5.0 to 5.5 mm; sexually
mature females, 4.5 to 6.0 mm. Very little is known about the life
cycle except that a single ovigerous female with two embryos was
collected from a pool in Skunk Cave, Winneshiek Co., Iowa (July
sample).
5. Stygobromus maokin-i Hubricht, 1943
Type Locality: Sikes Cave, Russell Co., Virginia.
The range of this rather common troglobitic species extends from
Monroe Co., West Virginia and Craig Co., Virginia south-southwestward
through the Appalachian valley to Roane Co., Tennessee (Fig. 27). S.
maokini. is more common in caves in the Clinch River valley (upper
Tennessee River drainage) of Tazewell, Russell, and Scott counties,
Virginia than anywhere else in its range. This species is commonly
found in drip and seep pools (often with mud-bottoms) of caves but
one record is from a covered spring in Washington Co., Virginia.
Sexually mature males, 5.0 to 7.5 mm; sexually mature females, 4.5 to
10.0 mm. Newly hatched young = approximately 1.7 mm. Ovigerous
females brood from four to ten eggs per clutch, depending on the size
of the female. Ovigerous females have been observed in spring and
summer and mature specimens have been found the year around. A number
of undescribed species of Stygobromus from caves in northwestern
Georgia, northern Alabama and eastern Kentucky are closely related to
S. maok-Lni,, and along with the latter, make up what appears to be a
significant species group within the genus.
6. Stygobromus onondagaensis (Hubricht and Mackin, 1940)
Type Locality: Onondaga Cave, Crawford Co., Missouri.
This small subterranean species is known primarily from caves in the
Ozark region of southcentral Missouri (Fig. 27). The majority of
samples (13 out of 20) have come from drip pools in caves, although
a few have been taken from small cave streams (four) and surface seeps
(three). Sexually mature males, 3.0 to 4.5 mm; sexually mature females,
3.5 to 6.0 mm (but rarely over 5.0 mm). Newly hatched young = approxi
mately 1.5 mm. Ovigerous females have been collected during the
summer and fall. In addition to S. onondagaensis, at least three
undescribed species of the genus occur in the Ozark region and all are
apparently closely related to the former.
7. Stygobromus putealis (Holmes, 1909)
Type Locality: Well at Waupun, Dodge Co., Wisconsin.
This species is currently known from five wells in three counties in
southeastern Wisconsin (Fig. 28). Of some zoogeographic interest is the
fact that S. putealis appears to be more closely related to species of
the S. hubbsi group from west of the continental divide than to any of
the middle-western species of the genus. Sexually mature males, 3.5 to
3.8 mm; sexually mature females, 4.5 to 6.0 mm. Ovigerous females are
not available and samples are too few to determine anything about the
biology of this species.
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8. Stygobromus sm-ithi Hubricht, 1943
Type Locality: S.C. Roden's well, Woodstock, Bibb Co., Alabama.
This rather distinct but apparently rare species is known only foom its
type locality and a seep in Tuscaloosa Co., Alabama (Fig. 29). Largest
male, 6.0 mm; largest female, 7.5 mm. Nothing is known about the bi-
ology of this species.
9. Stygobromus spinosus (Hubricht and Mackin, 1940)
Type Locality: Spring near Hawksbill Mountain, Madison Co., Virginia.
This rather unusual blind, white species inhabits small springs and
spring runs in the Blue Ridge Mountains of Northern Virginia, and its
range extends from Warren County south along the Skyline Drive (Shenan-
doah National Park) to Augusta County (Fig. 29). S. spinosus is often
abundant in the gravel substrate of spring runs, under dead leaves, and
in masses of aquatic vegetation. Sexually mature males, 4.0 mm; sex-
ually mature females, 3.5 to 5.5 mm. Ovigerous females and sexually
mature specimens occur in the spring but only samples from March, May
and June have been studied to date. A number of other species, all of
which are undescribed, have been collected from caves in the Appalachian
valley which lies adjacent to the Blue Ridge Mountains (Holsinger;
1969a). Descriptions of these species are in preparation by the writer.
10. Stygobromus vitreus Cope, 1872
Type Locality: Mammoth Cave, Edmonson Co., Kentucky.
This species is found in the Mammoth Cave area of southcentral Kentucky
with scattered populations in central Tennessee and northern Alabama
(Fig. 28). The Alabama populations differ slightly from those in Ken-
tucky, however, and may be subspecifically (if not specifically!)
distinct. S. vitreus inhabits small drip and seep pools in caves but is
occasionally found in surface seeps in the Mammoth Cave area. Sexually
mature males, 4.0 to 6.0 mm; sexually mature females, 3.5 to 7.0 mm.
The clutch size of ovigerous females ranges from four to ten eggs,
depending on size of the female. Ovigerous females occur in spring,
summer, and fall (and probably also in the winter) and mature specimens
are found the year around.
Figure 29. -- Distribution of species of Stygobromus in North America.
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Genus Bactrurus W.P. Hay, 1903
The Genus Baotrurus is composed of three described subterranean species
which occupy ground water biotopes (mostly seeps, drains, and caves) in
the middle-western United States. At least one undescribed species and
one undescribed subspecies also occur in this area. The genus is
endemic to North America, and while apparently closely related to
Stygoneates, it is easily distinguished from the latter by the third
uropod which has a larger outer ramus and the presence of a rudimentary
inner ramus.
Key to the Species of Bactrurus
1, Telson of male very long and cylindrical (Fig. 30a); palmar margins
of gnathopodal propods slightly concave; outer ramus of uropod
3 tapering apically. armed with only a few spines (Fig. 5f);
sexually mature specimens ranging in size from 8.0 to 15.5 mm:
B. mueronatus
Telson normal, not elongate or cylindrical in either sex; palmar
margins of gnathopodal propods straight to slightly convex;
outer ramus of uropod 3 rounded or blunt apically, armed with 10
to 12 spines (Fig. 30b); size of sexually mature specimens from
13.0 to 28.0 mm 2
2(1) Apical margin of telson entire or only slightly notched, armed with
rather short spines (Fig. 30c); size range of sexually mature
specimens from 15.0 to 28.5 mm: B. braehyoaudus
Apical margin of telson distinctly notched, armed with rather long
spines (Fig. 30d); size of sexually mature specimens from 13.0
to 21.5 mm: B, hubriehti
Annotated List of the Species
1. Bactrurus brachycaudus Hubricht and Mackin, 1940
Type Locality: Walled spring on Keifer Creek, 0.6 mile northwest of Fern
Glen, St. Louis Co., Missouri.
This large, subterranean species is found in cave streams, springs, and
seeps in southwestern Illinois and eastcentral Missouri (Fig. 31). Sex-
ually mature males reach 27.0 mm; sexually mature females range in size from
15.0 to 28.0 mm, with the average size of ovigerous females being 20.0 mm.
Sexually mature specimens occur throughout the year but ovigerous females
are rare in samples and so far are known only from collections made in June,
August, and September. The largest clutch size observed was 27 eggs in a
female, 20.0 mm long (August sample). The presence of mature and immature
animals in samples representative of all months of the year probably indi-
cate that at least some reproduction occurs throughout the year. There is,
however, a preponderance of juvenile and immature specimens in April samples,
thus implying the possibility of a seasonal reproductive peak.
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Figure 30. -- Structure of Baotruvus: a, telson of male of B.
rmcronatus; b, uropod 3 of B. hubriohti (based on Shoemaker,
1945); c, telson of B. brachyeaudus (based on Hubricht and
Mackin, 1940); d, telson of B. hubrichti (based on Shoemaker,
1945).
2. Bastrurus hubr-iahti Shoemaker, 1945
Type Locality: Well at Topeka, Shawnee Co., Kansas.
This poorly known species has a spotty distribution, with records from
eastern Kansas, eastcentral Oklahoma, and central Missouri (Fig. 31).
It is known primarily from wells but is occasionally found in seeps
(one in Kansas) and caves (one in Missouri). Sexually mature males,
15.0 to 21.5 mm; sexually mature females, 13.0 to 20.0 mm. Nothing
definitive is known of the life cycle except that mature specimens are
recorded throughout the year. Ovigerous females are unknown.
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3. Baatvurus muovonatus (Forbes, 1876)
Type Locality: Well at Normal, McLean Co., Illinois.
This rather common interstitial species is widely distributed from
central Ohio north to southern Michigan, across northcentral Indiana and
Illinois to southeastern Iowa; it also occurs in caves in Saline County
in southeastern Illinois (Fig. 31). This species is common in the out-
lets of drains in the glaciated areas of the middle-western United States
and is occasionally found in wells and caves. Sexually mature males, 9.0
to 15.5 mm; sexually mature females, 8.0 to 14.0 mm. Mature specimens
are found in samples taken throughout the year but ovigerous females have
not been observed. A closely related species or subspecies occurs in
seeps and cave pools in southcentral Missouri and northcentral Arkansas
and differs from B. mueronatus s. str. in being smaller at sexual maturity
and possessing median sternal processes. In this form, sexually mature
males are 9.0 to 13.5 mm and sexually mature females are 5.0 to 9.0 mm.
Ovigerous females are known from a sample made in May from a seep in
Douglas Co., Missouri. These ovigerous females were between 5.0 and 6.0
mm and some had up to 10 eggs per clutch.
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B. brachycaudus
B. hubrichti
;.': A-B. mucronatus s str.
'' B -8. mucronatus subsp 7
Figure 31. -- Distribution of species of Baotrurus in North America.
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Alloerangonyx Group
Genus Allocrangonyx Schellenberg, 1936
This unique subterranean genus is represented by two species that occupy
groundwater habitats in the Arbuckle Mountains of southcentral Oklahoma
and the Ozark plateau (Salem plateau section) region of central Missouri.
Although this genus shares some morphological affinities with both the
European genus Niphargus and the predominantly North American genus
CrangonyXj it also embraces an unusual combination of characters, making
it, in the writer's opinion, the single member of a distinct group of the
family Gammaridae. The evolutionary affinities and zoogeographic rela-
tionships of this genus were discussed in a recent paper by Holsinger
(1971).
Key to the Species of Alloarangonyx
1 Antenna 1 up to 65 percent as long as body in sexually mature ani-
mals; pereopod 7 about 55 percent as long as body; dactyls of
pereopods 6 and 7 without sets of spines on inner margins; outer
ramus of third uropod of sexually mature male with up to 5, rare-
ly 6, secondary segments (Fig. 32b); telson with 6 to 7 apical
spines per lobe: A. pellua-idus
Antenna 1 from 70 to 85 percent as long as body in sexually mature
animals; pereopod 7 from 65 to 70 percent as long as body;
dactyls of pereopods 6 and 7 with 3 sets of spines on inner
margins (Fig. 32a); outer ramus of third uropod of sexually
mature male with up to 16 (8-16) secondary segments; telson with
4 apical spines per lobe: A. hubrichti
Annotated List of the Species -
1. Alloorangonyx pelluo-idus (Mackin, 1935)
Type Locality: Bird's Mill Spring, Pontotoc Co., Oklahoma.
This species is known from cave pools, springs, and a seep developed in
the Ordovician limestones of the Arbuckle Mountains of southcentral
Oklahoma. The range extends from southwestern Murray County northeast-
ward to southern Pontotoc County (see Holsinger, 1971 for a distribution
map). Sexually mature males, 22.0 mm; sexually mature females, 18.0 mm.
Very little is known about the life cycle except that ovigerous females
have been observed in January and February.
2. Alloorangonyx hubTiohti Holsinger, 1971
Type Locality: Saltpetre Cave, Phelps Co., Missouri.
This species is easily distinguished from A. pelluaidus by the characters
given in the key and its geographic distribution. It is known only from
the small streams of two caves in central Missouri (Phelps and Pulaski
Counties). Very little data are available on life history, except that
a single ovigerous female (14.5) was found in a collection made in Octo-
ber and sexually mature adults were collected from the same cave in
August. The writer (Holsinger, 1971) reported a male, 15.0 mm long,
with nine secondary segments in the outer ramus of the third uropod.
77
-------
The third uropod was, in turn, 45 percent as long as the body. Topo-
typic material, collected since the description of this species, reveals,
however, that sexually mature males reach 18.0 mm in length and have up
to 16 secondary segments in the outer ramus of the third uropod. The
third uropods in larger males are 65 percent as long as the body. Sexu-
ally mature females range in size from 14.5 to 17.0 mm.
Figure 32. -- Structure of Alloorangonyx: a, dactyls of pereopods
6 and 7 of A. hubriohti; b, uropod 3 of mature male of A.
pellucidus.
78
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SECTION III
ACKNOWLEDGMENTS
The writer is grateful to the many persons who have contributed speci-
mens and related information used in the preparation of this manual
and to those who have assisted with the field work during the past
several years. Credits to individuals contributing specimens and
assisting with field work were given in earlier papers or will be given
in future ones. Several colleagues, including Dr. J. Laurens Barnard,
Dr. E. L. Bousfield, Dr. Thomas E. Bowman, Dr. Gerald A. Cole, Dr.
David C. Culver, Mr. Leslie Hubricht, and Dr. Milan Straskraba, offered
helpful advice and made useful comments, and their interest is appreci-
ated.
The writer- thanks the Smithsonian Institution for providing free access
to collections and facilities and Dr. I. E. Wallen, Director of the
Office of Environmental Sciences of that Institution, for his encourage-
ment of this project. Mrs. Carol H. Holsinger served as research
assistant and performed many useful tasks.
79
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SECTION IV
REFERENCES
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Benedict, James E. 1896. Preliminary descriptions of a new genus and
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Bousfield, E. L. 1958. Fresh-water amphipod crustaceans of glaciated
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1969. New records of Gammarus (Crustacea:Amphipoda) from the
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and J. W. Elwood. 1971. A new Gammarus (Crustacea:Amphipoda)
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Clemens, Howard P. 1950. Life cycle and ecology of Gammarus fasciatus
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Cole, Gerald A. 1970a. The epimera of North American fresh-water
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Cope, E. D. 1872. On the Wyandotte Cave and its fauna. American
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Greaser, Edwin P. 1934. A new genus and species of blind amphipod
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Culver, David C. 1970. Analysis of simple cave communities: niche sep-
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Ellis, T. Kenneth. 1940. A new amphipod of the genus Crangonyx from
South Carolina. Charleston Museum, Leaflet 13, pp. 3-8.
1941. A new fresh-water amphipod of the genus Stygobromus from
South Carolina. Charleston Museum, Leaflet 16, pp. 3-8.
Fabricius, J. C. 1775. "Systema entomologiae, sistens insectorum
classes, ordines, genera, species, adiectis synonyis, locus,
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Forbes, S. A. 1876. List of Illinois Crustacea, with descriptions of
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Hay, 0. P. 1882. Notes on some fresh-water Crustacea, together with
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Hay, W. P. 1902. Observations on the crustacean fauna of the region
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1903. Observations on the crustacean fauna of Nickajack Cave,
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Holmes, S. J. 1909. Description of a new subterranean amphipod from
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Holsinger, John R. 1966. Subterranean amphipods of the genus Stygonectes
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1967. Systematics, speciation, and distribution of the subterranean
amphipod genus Stygonectes (Gammaridae). United States National
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1969a. Biogeography of the freshwater amphipod crustaceans (Gammar-
idae) of the central and southern Appalachians, p. 19-50. In P. C.
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Appalachians Part I: Invertebrates." Research Division Monograph 1,
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1969b. The systematics of the North American subterranean amphipod
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1971. A new species of the subterranean amphipod genus Allocrangonyx
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82
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Holsinger- John R. and David C. Culver. 1970. Morphological variation
in Gammarus minus Say (Amphipoda, Gammaridae), with emphasis on
subterranean forms. Postilla, No. 146, 24 pp.
Hubricht, Leslie. 1943. Studies on the Nearctic freshwater Amphipoda,
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1959. Malacostraca (Amphipoda), pp. 876-878. In W. T. Edmondson
(Ed.) Ward £ Whipple "Freshwater Biology." John Wiley § Sons, Inc.,
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and C. H. Harrison. 1941. The freshwater Amphipoda of Island
County, Washington. American Midland Naturalist, 26:330-333.
and J. G. Mackin, 1940. Descriptions of nine new species of
freshwater amphipod crustaceans with notes and new localities for
other species. American Midland Naturalist, 23:187-218.
Hynes, H. B. N. 1955. The reproductive cycle of some British fresh-
water Gammaridae. Journal of Animal Ecology, 24:352-387.
Judd, W. W. 1963. Studies of the Byron Bog in southwestern Ontario
XVI. Observations of the life cycles of two species of Crangonyx
(Crustacea:Amphipoda). National Museum of Canada, Natural History
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Mackin, J. G. 1935. Studies on the Crustacea of Oklahoma, III:Sub-
terranean amphipods of the genera Niphargus and Boruta.
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Martynov, A. V. 1930. Fayna Amphipoda Teletzkoy Ozera i ee
Proisxozdenie. Izvestiya Gosudarstvennogo gidrologiches'kogo
instituta, 29:106-108.
Mills, Eric L. 1964. Noteworthy Amphipoda (Crustacea) in the collection
of the Yale Peabody Museum. Postilla, No. 79, 41 pp.
Minckley, W. L. and Gerald A. Cole. 1963. Ecological and morphological
studies on gammarid amphipods (Gammarus spp.) in spring-fed streams
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Verbreitung und ihre Arten. Mitteilungen aus dem Zoologischen
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Shoemaker, Clarence R. 1920. Amphipods. Report. Canadian Arctic
Expedition, 1913-18, Vol. 7, pt. E, 30 pp.
1938. A new species of fresh-water amphipod of the genus
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83
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Shoemaker, Clarence R. 1940. Notes on the amphipod Gammarus minus Say
and description of a new variety, Gammarus minus var. tenuipes.
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1941. A new subterranean amphipod of the genus Crangonyx from
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1942b. A new cavernicolous amphipod from Oregon. Occasional
Papers of the Museum of Zoology, University of Michigan,No. 466, 6pp,
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fur wissenschaftliche Zoologie, Leipzig. 28:403-406.
84
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SECTION V
GLOSSARY
Cavem-Loote. A species that completes all or at least part of its life
cycle in a cave; a cave inhabitant.
Ep-igean. The surface environment as opposed to the subsurface or sub-
terranean environment; the latter is often called hypogean.
Gvoundwater. Subsurface or subterranean water, sometimes directly
observable in caves and wells or in surface springs and seeps.
Interstital. Used in reference to both species and habitats.
Interstital species are usually defined as very minute forms (i.e., less
than 1 or 2 mm long) that live in the interstices between gravels and
sand grains. However, the term is sometimes applied to certain amphipods
as long as 10 mm (or rarely, longer) which inhabit cracks and crevices
saturated by groundwater.
Karst. The surface terrane in an area underlain by carbonate rocks
(usually limestone or dolomite), characterized by subsurface drainage
sinkholes, caves, bare rock ledges, and large springs.
Phreatobite. A species obligatory to subterranean waters but not
necessarily restricted to cave habitats (see definition of troglob-ite
below).
Seep. A place where groundwater flows (seeps) to the surface of the
ground. Seeps, in contrast to springs, are usually smaller and often
temporary or intermittent, depending upon the level of the ground water-
table at a.given time or place.
Subterranean. Used interchangeably with hypogean to refer to habitats
or species that exist or occur beneath the surface in caves, wells,
interstices, etc.
Syntopi-e. Two or more related species that occupy the same macrohabitat,
In comparison, sympathy refers to an overlap in range but not necessarily
in habitat.
Troglob-ite. A species obligatory to caves or related subterranean
habitats, usually distinguished morphologically by regression of
pigment and photoreceptors and frequently by longer, more attenuated
appendages than its epigean congener. Troglobite usually refers more
specifically to an obligatory cavernicole, while phreatobite is used
in a more general sense for obligatory groundwater species (see defini-
tion of phreatobite, above).
85
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SECTION VI
INDEX OF SCIENTIFIC NAMES
acherondytes (Gammarus), 12,19,21, Crangonyx gracilis, 28,30,33,36,44,
27,36 46
alabamensis (Stygonectes), 14,58,62 grandimanus, 28,41
alabamensis (Stygonectes), 62
occidentalis (Stygonectes), 62
allegheniensis (Stygonectes), 14,61
Allocrangonyx, 1,2,9,11,13,77
hubrichti, 77,78
pellucidus, 14,77,78
alpinus (Crangonyx), 28,33
Anisogammarus, 1
anomalus (Crangonyx), 28,31,32,33,
47,51 ;
antennatus (Crangonyx)3 12,14,16,28,
33,34
Apocrangonyx, 1,2,9,10,11,15,53 \
araeus, 10,14,52,53,54
ephemerus, 52,53,54
_ hobbsi, 28,29,30,41
'minor, 28,31,32,41,46,47
" obliquus, 28,32,33,41,43
\packardi, 14,28,29,30,44,68
pseudogvacilis , 28,29,30,44,46
richnondensis , 2 8
_ T-ichmondensis 3 33,43
_ laupent'ianus 3 33,43
_ occidentdlis, 33,43,44
rivulavis, 28,46
robertsij 28
\serratus, 28,31,32,44
setodactylus, 13,28,29,30,33,46,
47,51
shoemdkeri, 28,29,3 ,32,41,46,47
nortoni, 53,54 daiberi (Gammarus), 17
lucifugus, 53,54 dearolfi (Crangonyx), 28,33,34
parvus, 14,52,53,54 dejectus (Stygonectes), 63,65
subtilis, 52,53,54 dentata (Synurella), 14,33,47,48,49,
araeus (Apocrangonyx), 10,14,52,53, 51
54
, 1,2,11,15,73
bTa.chycau.dus, 36,73,74
hubT-ickti, 73,74
mucronatuSj 16,73,74,75
_
balcon-is (Stygonectes), 63
barri (Stygonectes), 63
~bi,fu?>ca (Syma>el~la) - 44,48,49
b-i,fia>catus (Stygonectes), 63
bousfieldi (Gcomarus) , 17,18,19,21
duebeni. (Gcamarus) ., 17
elatus (Stygonectes), 62
elki (Gammctfus), 17,25
emarginatus (Stygonectes), 14,56,57,
59,60
ephemerus (Apocvangonyx) 3 52,53,54
ex-ilis (Stygobromus) , 67,68
fasciatus (Garmavus) , 17,18,19,21,23
flagellatus (Stygonectes), 56,57,58,
64
bowmani (Stygonectes), 64 floridanus (Crangonyx), 4,28,29,30,34
brachycaudus (Bactrurus), 36,73,74 forbesi (Crangonyx), 4,16,28,29,31,32,
breviramus (Gammarus), 20, 21 36
chamberlaini (Synurella), 48, 49 Gammarus, 1,2,3,9,10,11,13,17
clantoni (Stygonectes), 64
conradi (Stygonectes), 60
cooperi (Stygonectes), 59
Crangonyx, 1,2,4,8,9,11,13,28,48
alpinus, 28,33
anomalus, 28,31,32,33,47,51
antennatus, 12,14,16,28,33,34
dearolfi, 28,33.34
floridanus, 4,28,29,30,34
forbesi, 4,16,28,31,32,36
bousfieldi, 17,18,19,21
breviramus, 20,21
daiberi, 17
duebeni, 17
elki, 17,25
fasciatus, 17,18,19,21,23
lacustris, 20,23
lacustris, 23
lirmaeus, 23
87
-------
Gammarus minus, 4,12,17,18,20,21,25, pelluoidus (Alloorangonyx), 14,77,
27,59,60 78
pinioollis, 25 pizzinii (Stygoneotes). 57,60,61
palustris, 17 Pontoporeia affinis, 1
peaos, 18,19,27 propinquus (Gammarus) _, 25
propinquus, 25 pseudogracilis (Crangonyx), 28,29,
pseudolirmaeus, 17,19,20,27 30,44,46
purpurascens, 25 pseudolimnaeus (Gammarus), 17,19,
robustus, 24 20,27
tigrinus, 17,23 purpurasoens (Gammarus), 25
troglophilus, 4,17,18,19,21,27,36 pusillus (Stygobromus), 65
graoilipes (Stygoneotes), 60 putealis (Stygobromus), 67,71
graoilis (Crangonyx), 28,30,33,36,44, reddelli (Stygoneotes), 63
46 vichmondensis (Crangonyx), 28
grandimanus (Crangonyx), 28,41 laurentianus (Crangonyx), 33,
hadenoeaus (Stygoneates), 57,58,65 43
hayi (Stygoneotes)_, 62 occidentalis (Crangonyx), 33,
heteropodus (Stygobromus)J 65,66,68 43,44
hobbsi (Crangonyx),, 28,29,30,41 Tichmondensis (Crangonyx) , 33,
hortoni (Apocrangonyx)} 53,54 43
hubbsi (Stygobromus), 66,67,68,69,71 rivularis (Crangonyx)3 28,46
hubriGhti (Allocrangonyx), 77,78 Rivulogammarus, 17
(Baetrurus), 73,74 robertsi (Crangonyx)3 28
Hyalella azteoa, 1 robustus (Gammarus), 24
indentatus (Stygoneotes), 16,58,61 russelli (Stygoneotes), 63
iowae (Stygobromus), 68,71 serratus (Crangonyx), 28,31,32,44
laoustris (Gammarus), 20,23 setodaotylus (Crangonyx), 13,28,29,
laoustris (Gammarus), 23 30,33,46,47,51
limnaeus (Gammarus), 23 shoemakeri (Crangonyx), 28,29,31,
luaifugus (Apoorangonyx), 53,54 32,41,46,47
johanseni (Synurella), 48 smithi (Stygobromus), 66,67,72
longipes (Stygoneotes), 56,64 spinatus (Stygoneotes). 56,57,59,
maokini (Stygobromus), 67,71 60
minor (Crangonyx), 28,31,32,41,46,47 spinosus (Stygobromus), 67,12
minus (Gammarus), 4,12,17,18,20,21,25,stellmaoki (Stygoneotes), 60
27,59,60 Stygobromus, 1,2,10,11,15,44,59,65
pinioollis (Gammarus), 25 exilis, 67,68
montanus (Stygoneotes), 62 heteropodus, 65,66,68
morrisoni (Stygoneotes), 59 hubbsi, 66,67,68,69,71
muoronatus (Bactrurus), 16,73,74,75 iowae, 68,71
mundus (Stygoneotes) 59 maokini, 67,71
Niphargus, 77 onondagaensis, 66,67,71
obliquus (Crangonyx), 28,32,33,41,43 pusillus, 65
oocidentalis (Stygoneotes), 62 putealis, 67,71
onondagaensis (Stygobromus), 66,67,71 ^^ smithi, 66,67,72
ozarkensis (Stygoneotes), 64 spinosus, 67,72
paokardi (Crangonyx), 14,28-30,44,68 3ZI vitreus, 66,68,72
palustris (Gammarus), 17 Stygonectes, 1,2,9,10,11,15,53,
parvus (Apoorangonyx), 14,52,53,54 55
peoki (Stygoneotes), 65 alabamensis, 14,58,62
peeos (Gammarus), 18,19,27 alabamensis, 62
88
-------
Stygoneotes dlabamensis oooidentdlis,
62
allegheniensis, 14,61
baloonis3 63
barvi, 63
bifuToatus3 63
bowmani3 64
olantoni, 64
oonvadi, 60
coopevi, 59
delectus, 63,65
elatus, 62
emarginatus3 14,56,57,59,60
fla.gella.tus3 56,57,59,60
gvaailipes, 60
hadenoeous3 57,58,65
hayi, 62
indentatus, 16,58,61
longipes, 56,64
montanus, 62
yy- _ ~si~f.Jf .^ s^-*/\ *»* CO
mundus, 59
ozarkensis, 64
65
57,60,61
63
63
spinatus3 56,57,59,60
stellmaakij 60
tenuis, 57,61
tennis, 61
potomaouSj 61,62
subtilis (Apoorangonyx)3 52,53,54
Synp1eonia3 55
Synurella, 1,2,4,8,9,11,13,48
bifuToa, 44,48,49
ahamberlaini, 48,49
dentata, 14,33,47,48,49,51
johanseni3 48
tenuis (Stygoneotes)3 57,61
tenuis (Stygoneotes), 61
potomacus (Stygoneotes), 61,62
tigrinus (Gccmmarus)., 17,23
tToglophilus (Gammarus), 4,17,18,19,
21,27,36
yitveus (Stygobromus) ., 66,68,72
89
-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
1. Report No.
3. Accession No.
w
4. Title BIOTA OF FRESHWATER ECOSYSTEMS IDENTIFICATION MANUAL
NO. 5 The Freshwater Amphipod Crustaceans (Gammaridae) of
North America.
7. Author(s)
Holsinger, J.R.
9. Organization Old Dominion University
Norfolk,
Virginia
12. Sponsoring Organization
15. Supplementary Notes
5. Report Date
6.
8. Performing Organization
Report No.
10. Project No.
18050 ELD
11. Contract/Grant No.
14-12-894
13. Type of Report and
Period Covered
16. Abstract The amphipod crustacean family Gammaridae is represented in the fresh-
waters of North America by eight genera and 81 described species;
numerous other species are still undescribed. These eight genera,
with the number of described North American freshwater species in
parentheses, include: Gommorus (9), Crongonyx (18), Synurella (4),
Apoerangonyx (6), Stygoneates (29), Stygobromus (10), Baotrums (3),
and Alloarangonyx (2). Ecologically, the freshwater gammarids are
an important group of aquatic invertebrates, with species found in a
variety of biotopes, including lakes, streams, ponds, swamps, springs,
and subterranean waters.
The identification of amphipods is rather difficult, especially because
accurate determinations often depend on the recognition of diagnostic
character combinations and the study of the whole morphology of the
animals. In order to facilitate the identification of genera and the
determination of species, analytical keys with accompanying illustrations
are presented. Of further assistance are the inclusion of distributional
maps showing the ranges of many of the species. A brief synopsis of
pertinent ecological information and the type locality for each species
are also given.
na.Descriptors *Aquatic fauna, *Amphipoda, Preservation, Distribution
I7b.identifiers identification Manual, *Illustrated key, *Crustacea, *Gammaridae,
*North America, Species List, Collection, Ecology
17c. COWRR Field & Group 10A
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. DEPARTM ENT OF THE INTERIOR
WASHINGTON, D. C. 20240
Abstractor Holsinger, John R.
\institution Old Dominion University, Norfolk, Va.
VRSIC 102 (REV. JUNE 1971)
U. S. GOVERNMENT PRINTING OFFICE : 1972 O - 467-253
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