WATER POLLUTION CONTROL RESEARCH SERIES • 18050 EUDO4/72
BIOTA OF FRESHWATER
ECOSYSTEMS
Identification
Manual
AQUATIC
DRYOPOID BEETLES
(COLEOPTERA)
OF THE
UNITED STATES
U.S. ENVIRONMENTAL PROTECTION AGENCY
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Biota of Freshwater Ecosystems
Identification Manual No. 6
AQUATIC DRYOPOID BEETLES (COLEOPTERA) OF THE UNITED STATES
by
Harley P. Brown
Department of Zoology
The University of Oklahoma
730' Van Vleet Oval, Room 222
Norman, Oklahoma 73.Q69
for the
ENVIRONMENTAL PROTECTION! AGENCY
Project # 18050 ELD
Contract # 1,4-12-894
April 1972
For sale by /the Superintendent of Documents, VS. Government Printing. Office
Washington, D.C. 2.04)02 - Price $2.50
Stock Number 5501.-0370
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EPA Review Notice
This report has been reviewed by the Environ-
mental Protection Agency, and approved for
publication. Approval does not signify that
the contents necessarily reflect the views
and policies of the EPA, nor does mention of
trade names or commercial products constitute
endorsement or recommendation for use.
WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Series describes the
results and progress in the control and abatement of pollution
in our Nation's waters. They provide a central source of
information on the research, development, and demonstration
activities in the water research program of the Environmental
Protection Agency, through inhouse research and grants and
contracts with Federal, State, and local agencies, research
institutions, and industrial organizations.
Inquiries pertaining to Water Pollution Control Research
Reports should be directed to the Chief, Publications Branch
(Water), Research Information Division, R&M, Environmental
Protection Agency, Washington, DC 20460.
11
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FOREWORD
''Aquatic Dryopoid Beetles (Coleoptera) of the United States"
is the sixth of a series of identification manuals for se-
lected taxa of invertebrates occurring in freshwater systems.
These documents, prepared by the Oceanography and Limnology
Program, Smithsonian Institution for the Environmental Pro-
tection Agency, will contribute toward improving the quality
of the data upon which environmental decisions are based.
Additional manuals will include, but not necessarily be lim-
ited to, freshwater representatives of the following groups:
branchiuran crustaceans (Argulus}, amphipod crustaceans
(Gammaridae), isopod crustaceans (Asellidae), decapod cray-
fish crustaceans (Astacidae), leeches (Hirudinea), polychaete
worms (Polychaeta), freshwater planarians (Turbellaria), and
freshwater clams (Sphaeriacea).
111
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ABSTRACT
An illustrated key is given for all known species of adult dryopoid
beetles of the United States which have aquatic stages and might be
useful as indicators of water quality. A key is also given to the
genera of larvae. For each species the known habitat and range are
given. Life histories are briefly outlined and methods for collection,
preservation, storage and identification are suggested. Two new
species, Optioservus ozarkensis Collier and Optioservus sandevsoni
Collier, are described. The genera included in the keys are:
Chelonariidae--C7zeZ.on
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CONTENTS
Section Page
I Introduction 1
Collecting 4
Preservation and Storage 6
Preparation and Equipment Needed for Identification 7
II Species List and Ranges 13
III Key to Aquatic Genera and Species of Adult Dryopoid Beetles 25
of the United States
IV Key to Genera of Aquatic and Semi-aquatic Dryopoid Beetle 55
Larvae of the United States
V References 69
VI Glossary 73
VII Index of Scientific Names 79
VII
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FIGURES
Page
1-2 Adult elmid beetle: external features 8
3-7 Adult elmid beetle: lateral and sectional views; mouthparts 8
8-11 Adult elmid beetle: digestive, nervous, and reproductive systems9
12-15 Elmid larva: external features, mouthparts 10
16 Chelonariim leoontei adult 25
17-18 PhanooeTus clavicornis, Lara avara adult 26
19-21 Lara gehringi, L. avara avara3 L. a. amplipennis adult 27
22-23 Maoronyahus glabratus, Anayronyx variegata adult 27
24-25 Zaitzevia parvula, Ordobrevia nubifera adult 28
26 Stenelmis orenata adult 29
27-35 Tarsus, aedeagus of Stenelmis species 29
36-41 Aedeagus of Stenelmis species 31
42-48 Aedeagus of Stenelmis species 32
49-54 Aedeagus of Stenelmis species 33
55-56 Rhizelmis nigva adult 34
57 Cleptelmis ornata adult 35
58-59 Atraotelmis wawona adult 36
60-61 Ampumixis dispar, Narpus concoloT adult 36
62-63 Dubivaphia quadrinotatas Elsianus texanus adult 37
64-65 Neocylloepus boeseli, Neoelmis oaesa adult 38
66-67 Hexacylloepus ferrugineust Heterelm-is vulnerata adult 39
68-69 Cylloepus parkeri adult 40
70-71 MioTOGylloepus pusillus, Oulirmius latiusoulus adult 41
72-73 Gon-ielmis dietviohi, Promoresia elegans adult 42
74-75 Heterlimnius corpulentus, Optioservus ovalis adult 43
76-82 Adult pronotum and elytron of Heterlirmius, Optioservus species44
83-89 Adult pronotum and elytron of Optioservus species 45
90-91 Dryops arizonensis3 Pelonomus obscwms adult 46
92 Hel-Lohus lithophilus adult 47
93-98 Hel-iohus confluentus, H. irmsi genitalia 47
99-104 Eelichus productus, H. Uthophilus genitalia 48
105-114 Aedeagus of Eelichus species 49
115-116 Throsoinus sohwartzi., Lirrmiohus sp. adult 50
117-118 Lutrochus luteuSj Aaneus quadrimaoulatus adult 52
119-120 Ectopr-ia neroosa, D'ioranopselap'hus sp. adult 52
121-122 Eubpianax edwa?>dsi3 Psephenus texanus adult 53
123-128 Aedeagus of Psephenus species 53
129-131 Anchycteis ve1uti,na3 Anchytarsus substviatus3 Stenocolus
soutellaris adult 54
132-133 Larvae of Chelonopium sp., Dvyops sp. 55
134-135 Larvae of Anchytarsus bieolor, Stenocolus scutellaris? 56
136-138 Larva of Lutroohus luteus 57
139-142 Larvae of Lara aoaya, Phanocerus olavicornis 58
143-146 Larvae of Dubiraphia sp., Narpus eoncolor 59
147-150 Larvae of Cylloepus sp., C. montanus, Rhizelmis nigra 59
151-155 Larvae of Ancyronyx variegata, Heterelmis vulnevata 60
156-160 Larvae of Microcylloepus pusillus, Neoelmis sp. 61
vin
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FIGURES - continued
161-164 Larvae of Neoeylloepus boeseli, OvdobTevia nubifera 61
165-168 Larvae of Elsianus texanus, Stenelmis sp. 62
169-172 Larvae of Ampwnixis di-spar, Cleptelmis sp. 63
173-177 Larvae of Promoresi-a -bordello., Optioservus sp. 63
178-181 Larvae of Maoronyohus glabrabus, Zaitzewia parvula 64
182-184 Larva of Gonielmis die-tvidhi 65
185-188 Larvae of Eetevelmis oorpulentus, Oulirmius latiusculus 65
189-190 Larva of Aaneus quadrimaeulatus 66
191-194 Larvae of Diaranopselaphus sp., Eatopria nervosa 66
195-198 Larvae of Eubrianax edwardsi, Psephenus texanus 66
IX
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SECTION I
INTRODUCTION
For practical purposes, one may consider any non-swimming aquatic
beetle found in the United States to be a dryopoid. Although a few,
such as Psephenus and LutroehuSj may be relatively conspicuous on rocks
projecting from riffles, the majority are very small, inconspicuous,
and slow-moving. Since the typical habitat of almost all dryopoids is
in riffles, rapids, or comparable lotic situations, the common name
"riffle beetle" is generally appropriate. Furthermore, since one
author or another has applied this name to the dryopoids alone, the
elmids alone, or the psephenids alone, while others have used it indis-
criminately for all, it might as well be used for the entire group of
aquatic dryopoids.
The Superfamily Dryopoidea, in the Suborder Polyphaga, includes members
(the Limnichidae) that are very close to the Byrrhoidea, and others
that are closely allied to the Dascilloidea (most of the genera listed
under Psephenidae and Ptilodactylidae are treated as members of the
family Dascillidae by Arnett (1963)). Crowson (1967) considers the
Superfamily Dryopoidea as being comprised of the families Psephenidae,
Eurypogonidae, Ptilodactylidae, Chelonariidae, Heteroceridae,
Limnichidae, Dryopidae, and Elmidae. The Eurypogonidae and
Heteroceridae are omitted from treatment here since none of our
representatives of these families are known to be aquatic, although
the heterocerids burrow in mud along the margins of streams, ponds,
and lakes. By far the most promising as indicators of water quality
are the elmids, but the psephenids, adults of Hel-ichus (Dryopidae),
and larvae of Lutroohus (Limnichidae) should also be useful for this
purpose.
Although somewhat detailed information concerning habitats of individual
genera and species is presented in the species list, a few general facts
concerning dryopoid life histories and ecology may be helpful. The
elmids of the tribe Elmini are the most completely aquatic of all
beetles. The eggs, so far as is known, are deposited on submerged
rocks or wood, usually on the under side. Here the larvae develop,
creeping about and feeding chiefly upon the algae which tend to encrust
such substrates or upon decaying waterlogged wood. Respiration is
accomplished by tufts of filamentous tracheal gills which are extruded
from a caudal chamber. The gills may be retracted and the chamber
closed by a trapdoor-like operculum. Mature larvae crawl out of the
water and pupate in small cavities beneath loose bark or rocks close
to the water's edge. Newly emerged adults of many species apparently
fly at night, and are attracted to lights. Upon returning to the water,
most individuals will never again emerge into the air, spending the
rest of their lives (several years in some species) in the same habitat
and utilizing the same food as the larvae. Their respiratory
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requirements are met through the use of a plastron (Thorpe, 1950;
Thorpe and Crisp, 1949). Various parts of the legs and body, especially
on the ventral side, are covered with a hydrofuge tomentum or pile which
maintains a film of air when the beetle is submerged. This film, which
is in contact with the air reservoir beneath the elytra, provides
adequate gaseous exchange in the well-aerated lotic situations occupied
by the beetles. Small bubbles of oxygen photosynthetically produced by
algae and other aquatic plants provide an additional source of oxygen
and can be incorporated into the plastron. Since the gaseous film is
essential to these beetles, it is not difficult to understand why they
cannot tolerate excessive pollution by such wetting agents as soaps and
detergents.
Elmids of the tribe Larini are less thoroughly aquatic. The adults are
essentially riparian, usually occurring at or just above the water line
in rapids and creeping beneath the surface only for oviposition
(presumably). They take flight readily, often after dropping onto the
water surface and being swept a short distance downstream. Otherwise,
the life history is like that of the Elmini.
Psephenus and Eubrianax^ in the family Psephenidae, exhibit a pattern
very much like that of the Larini, except that the females may remain
submerged for days as they go about their task of oviposition beneath
rocks. Mature larvae (water pennies) crawl out and pupate beneath the
larval carapace. Details are unknown for the members of the Eubriinae,
but since the adults are found in shrubbery rather than at the water's
edge, it is quite possible that the adults never enter the water, perhaps
ovipositing on objects overhanging the stream as do such neuropterans as
the sisyrids and dobsonflies. Pupation, at least in Ectopria, is
comparable to that in Psephenus.
In the family Limnichidae, Lutrochus has a life history that is also
very much like that of the Larini, although the adults of some species
may enter and remain under water for indefinite periods of time.
Females insert their eggs in such substrates as travertine. The other
genera of limnichids occurring within the United States are apparently
not aquatic even as larvae. Their life histories are unknown. The
adults are included in the key only because they may be taken near water
(in fact, L-irm-ichus commonly falls onto the water from trash lodged in
the stream, and readily flies from the water surface as do LutrochuSj
Psephenusj Phanocerus, and Lard].
Chelonarium (Chelonariidae) is aquatic only in the larval stage, as are
those members of the Ptilodactylidae listed here. Other ptilodactylids
are not aquatic at all.
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of the family Dryopidae, is unique among insects in that the
adults are aquatic, behaving rather like elmids, whereas the larvae are
terrestrial, inhabiting soil or decaying wood. The adults are not
permanently bound to the water once they return to it. They probably
emerge and fly at night, at least upon occasion. The females have sharp-
tipped ovipositors with which they probably insert their eggs into
appropriate materials. The larvae of Dryops and Pelonomus 'are also soil-
dwellers, the adults being terrestrial or, at most, riparian. Dryops
frequents trash lodged in streams, but does not appear to enter the
water.
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COLLECTING
With a few notable exceptions, such as Psephenus and Eubrianax among the
psephenids and such flightless elmids as Ancyronyx and Maeronychus most
of our dryopoid adults can be effectively collected with light traps and
black lights. To be successful with this method, of course, one must use
it when the adults have emerged from pupation. The best time will vary
with locality, seasonal and weather conditions, and species. For example,
in Oklahoma in an average year, Ectopna may be taken in abundance at
lights on humid nights in very late May and early June; at other times
they are unlikely to be taken. Specimens collected at lights are ideal
for taxonomic purposes, at least in that they are not encrusted with
mineral deposits or bedecked with epizoic organisms such as diatoms and
ciliates.
Perhaps the most useful general method of collecting the aquatic larvae
and adults that inhabit gravelly and rocky riffles is to hold a delta net
against the bottom in such a way as to catch the organisms dislodged
while turning over rocks just upstream from the net, or vigorously
stirring up the gravel by hand, heel, alpenstock, or whatever is at hand.
(A small rake serves rather well.) This is probably the best method for
most of the elmids and Heliehus.
Nets are not effective for most of the species that cling tightly to
submerged-wood or plants. Usually one must remove logs or sticks from
the water, turn them over, let them drain briefly, then laboriously pick
off the specimens as they creep downward. The same can be done, with
rocks, and this is often very productive. Or one can place the stick or
rock over a white pan or old sheet and let the specimens collect them-
selves (they will accompanied, of course, by caddis worms and most of
their other former neighbors). These techniques are best for such genera
as AnGyronyXj Macvonyckus, Gon-ie1m-is3 and Hetevelm'is. Most larval
psephenids must be picked off the rocks.
For species that inhabit such things as submerged plants or roots, a
Berlese funnel may be the most productive collecting device. Quantities
of the plant materials can be transported in large plastic bags to the
laboratory and placed in the funnel beneath some source of heat (light
bulbs are adequate). A screen of hardware cloth prevents the larger
objects from falling below, but the beetles will drop into a waiting
receptacle of preservative. This is a good method for getting large
numbers of Dubiraphia.
Disturbing trash (leaves, etc.) lodged on sticks or rocks in streams
while holding a net downstream to catch the dislodged specimens being
swept down afloat is effective for collecting DTyops} Limni-chuSj
Phanoaerus., Psephenus3 and Lutroahus, For dislodged specimens swept
downstream underwater, it is good for getting Heliohus3 Heterelmi-s} and
MiorooyIloepus.
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For agile fliers such as Psephenus and Lutroahus on rocks protruding
from rapids or riffles, a net or plastic bag may be useful for catching
the specimens that tumble onto the water to be swept downstream briefly
before taking flight, but many specimens can be taken by aspirator or by
hand (it is best to wet your fingers first). Approach the beetle care-
fully . without sudden movements, and pin it down lightly with a fore-
finger. The thumb and middle finger can then be used to grasp it.
Sweeping foliage of trees and shrubs near streams may yield adults of
the Eubriinae, Chelonariidae, and Ptilodactylidae. This is not very
efficient, but no better method is known for collecting some of these.
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PRESERVATION AND STORAGE
For routine collecting, a supply of 4-dram vials almost full of 80%
ethyl alcohol is handy. Fine-tipped forceps, preferably of the curved
type, are indispensable. If not young and near-sighted, the collector
should have either magnifying glasses or glasses enabling him to read
fine print.
For ordinary purposes, 70-80% ethyl alcohol is satisfactory for killing,
transport, and storage of both larvae and adults. If one anticipates
detailed dissection of internal parts, it may be better to preserve
initially in Pampl's fluid, which contains acetic acid for rapid pene-
tration. Specimens should be removed from Pampl's fluid to 70-80%
alcohol for storage. Whether the insects have been killed in alcohol or
in Pampl's fluid and then transferred to alcohol, if is best to change
the alcohol after a few days. It is also sometimes desirable to add
about 5% glycerol to the alcohol in which specimens are stored. This
serves a dual function: it helps keep the appendages flexible and,
should the cap not prove airtight, prevents complete drying of the
specimen if all the alcohol evaporates.
Pampl's Fluid
Glacial acetic acid 4 ml
Distilled water 30 ml
Formalin (40% formaldehyde) 6 ml
95% ethyl alcohol 15 ml
A common and sensible museum storage method for specimens preserved in
alcohol is to place the specimens in vials, along with appropriate data
and alcohol, to plug with cotton or cotton wool, then to place upside
down for storage in a larger jar half filled with alcohol. Cheap shell
vials are satisfactory for this, and many can be kept in a single jar.
If vials are to be stored instead in narrow trays, it is probably best
to use patent lip vials with rubber stoppers. Cork stoppers are
totally unreliable, and a discouraging percentage of screw-cap vials
allow evaporation of the alcohol because of imperfections of either the
lip or the cap liner.
For standard dry preservation of adults in Schmitt boxes or cabinet
drawers, virtually all of our dryopoid beetles are small enough for the
use of points. In fact, most are so small that they cannot be pinned
otherwise, even with minuten nadeln.
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PREPARATION AND EQUIPMENT NEEDED FOR IDENTIFICATION
For identification of genera or species, a stereoscopic microscope, spot
lamp, forceps, and fine needles are necessities. Disposable hypodermic
syringe needles (e.g., No. 26) attached to any convenient handle make
excellent micro-scalpels. All dissections and most examination of
material, particularly of larvae, should be done with the specimen
immersed in water or alcohol. For specific determination in some genera,
such as Stenelmis3 it is necessary to extract the male genitalia and to
mount them on a microscope slide for examination under a compound micro-
scope. Glycerol (glycerine) is satisfactory for temporary microscopic
preparations. Hoyer's mounting medium (obtainable from Ward's Natural
Science Establishment, Rochester, New York) is quite convenient for
temporary and semi-permanent mounts. Canada balsam is perhaps best for
permanent mounts, though it is time-consuming, since specimens must be
completely dehydrated through a graded series of alcohol concentrations,
then saturated with a suitable solvent such as xylol or toluol, before
placing in the balsam.
Most specimens as brought in from streams are well covered with either
mineral deposits (sometimes far exceeding the weight of the insect) or
epizoic organisms such as diatoms and peritrich ciliate protozoa. A
sonic cleaning tank is helpful, but removes only the rather loosely-
adhering "dirt". A closely-trimmed camel's-hair brush is also quite
useful in cleaning specimens, but often only breaking of the mineral
"armor" with forceps or scraping with a needle can reveal the surface
of the insect. Care must be exercised in such scraping, for it is easy
to scrape through the cuticle and artificially produce misleading mark-
ings or coloration.
When required for specific determination, genitalia may be removed in
at least two ways: (1) using a stereoscopic microscope to observe, hold
the specimen between the thumb and forefinger of one hand; with fine-
tipped watchmaker's forceps in the other hand, insert the tips between
the last abdominal sternite and elytral apex (Figs 1, 2); grasp and ex-
tract whatever you can. With a little experience, one can usually
remove the genitalia by this means. The other method is usually more
destructive to the specimen. (2) Remove either the abdomen (it can
often be glued back into place if necessary) or the elytra. This
exposes the soft dorsal tergites of the abdomen, through which an
incision can be made - or the whole dorsum torn off- to expose the
underlying visceral organs. Usually the only prominent sclerotized
structure in the abdomen of the male is the genital complex. This can
be removed and teased apart in appropriate fashion. As a rule, the
soft enclosing tissues must be torn away, along with the penial spicules
(Fig. 10) in order to expose the genitalia. Further cleaning and clear-
ing can be accomplished by placing the genitalia in a hot aqueous
solution of strong potassium hydroxide for about 15 minutes. After
rinsing in distilled water, then 70% alcohol, the specimen may be
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hind wing showing venation
(as unfolded for flight)
apical segment
of antenna
vertex of head
apical angle of
pronotum
crenate lateral
margin
sublateral cacina
scutellum
umbone, humerus, or
humeral angle
sublateral carmae
of elytron
punctae of first
stria
sutural interval
serrate lateral
margin
pleural spiracle
tergite
edge of 4th
sternite
apex of elytron
Fig. 1. Dorsal features of adult elmid beetle.
first or basal segment o
antenna
clypeus
labrum
mandible
labrum
maxillary palp
labial palp
gena
hypomeron
prosternal episternum
(prosternal epimeron)
prosternal process
mesosternal episternum
mesosternal epimeron
mesosternum
met asternal episternum
epipleuron (=elytral
hypomeron)
metacoxal cavity
coxa
trochanter
femur
3rd abdominal sternite
tibia with tomentum
produced margin of
sternite which clasps
epipleuron of elytron
1 st segment of tarsus
tarsal claw
Fig. 2. Ventral features of adult elmid beetle.
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pronotal hypomeron
pronotum
lateral margin ot elytron
/;sublateral carinae
pipleuron
melasternum
trachea
carma of elytron
hind wing
heart
abdominal tergite
serrate margin
(tubercle)
gonad
spiracle Cin pleuron)
malpighian tubule
gut
muscle
epidermis
abdominal stermte
(cuticle)
ventral nerve cord
apical tooth
lateral lobe
prostheca
gula
Figs 3-7 Adult elmid beetle: 3- lateral aspect; 4- diagrammatic
cross section through abdomen; 5- mandible of Hetevelmis 6- maxilla,
right side, ventral aspect, of Neooylloepus; 7- labium, ventral as-
'pect, of Neocylloepus.
mounted in Hoyer's medium and examined promptly. By jiggling of the
cover glass with a needle, one can usually get the specimen into the
necessary position for observation (at times a dorsal view is needed,
at other times, a lateral or ventral view may be desired). Since
Hoyer's medium is soluble in either alcohol or water, the specimens may
be readily removed even after months on the slide.
A formidable vocabulary has arisen for the description and classification
of beetles. This is not surprising, in view of the fact that they repre-
sent the largest order of plants or animals. Nor is it surprising that
some terms have been used in diverse ways or that a number of different
terms have been used for a particular structure. Figures 1-15 should
assist the reader not only in making use of the following keys but also
in understanding the more detailed references he may consult. These are
diagrams or simplified figures of representative dryopoid beetles,
illustrating the major morphological features and the terms most commonly
applied to them. The figures should be useful even though some of the
terms are not employed in the keys. It will be worthwhile to study Figs
1-15 with care before attempting to use the keys. These figures serve
as an illustrated glossary, though a standard form of glossary is appen-
ded (p. 73).
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fore gut (stomodeum)
cecum
mid gut (mesente^on)
malpighian tubule
unction of rnid gut
and hmd gut
hind gut (pcoctodeum)
• circumesophageal
connective
subesophageal ganglion
• 1st thoracic ganglion
? fused 5th to 8th
abdominal ganglia
sperm tube or
lobe of testis
vas efferens
lateral accessory
gland
median lateral
accessory gland
seminal vesicle
ejacutatory duct
penial spicule
basal piece or "I
lobe
paramere or
lateral lobe I
penis or median lobe
ostium ol internal sac
aedeagus or
male gemtalic
egg tube or ovanole
spermathecal gland
spermatheca
lateral oviduct
median oviduct
spermathecal duct
bursa copuiatnx
vagina
baculum (valvifer)
hemisternite (coxite)
stylus (may protrude
female
gemtalia
Figs 8-11 Adult elmid beetle: 8- dorsal aspect of digestive tract
of Neoeylloepus; 9- central nervous system of Neocylloepusj
10- male reproductive system, dorsal aspect, of Neocylloepus;
11- female reproductive system, dorsal aspect.
If the reader is unfamiliar with insects, he would be well advised to
consult a general textbook of entomology. For general coverage of
aquatic insects, two books are outstanding. The sections of these books
dealing with the Coleoptera are cited in the bibliography: Leech and
Chandler (1956), and Leech and Sanderson (1959). Both were extremely
helpful to me in the preparation of the keys which follow, as was the
work of Sanderson (1953-54).
10
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Among the beetles treated in these keys are groups of species which
need revision. In the absence of described characters which clearly
distinguish species, geographical location is used in the key so that
identification may be made according to published accounts.
antenna
frontal tooth
frontal suture
maxilla
labium
pronotum
prosternum
spiracular
tubercle
mesonotum
mesosternum
metanotum
metasternum
2 nd abdomina
tergite
4th abdominal
sternite
5 th abdomina
pleurite
sternopleural suture
tergopleural suture
operculum of
chamber
opercular hook or claw
— gill filaments
palp
stipes
cardo
palp
Figs 12-15 Elmid larva (Neocylloepus*) : 12- dorsal aspect;
13- ventral aspect; 14- left maxilla, ventral aspect; 15- labium,
ventral aspect.
11
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SECTION II
SPECIES LIST AND RANGES
In this section two new species, Optioservus ozarkensis and 0.
sandersoni, are described by Joe Edward Collier. He submitted his Ph. D.
thesis (Collier, 1969) to the Graduate School of the University of
Minnesota in August, 1969 but died of cancer that same month. His Major
Professor, Dr. Edwin F. Cook, has authorized publication here of
Collier's descriptions as a means of validating Collier's authorship of
these two species. The descriptions presented here are taken from
Collier's thesis and authorship is to be ascribed solely to Joe Edward
Collier.
Family CHELONARIIDAE (Lacordaire, 1854)
Genus Chelonarium Fabricius, 1801
Chelonariim leoontei Thomson, 1867. Though probably not really aquatic,
larvae in damp moss may be washed into streams; adults usually on
vegetation or taken at lights in southeastern states from Florida
to North Carolina, Tennessee, and Alabama.
Family ELMIDAE (ELMINTHIDAE) (Westwood, 1838)
Tribe Larini
Genus Lava LeConte, 1852
Lara avara avara LeConte, 1852. Rapid, clear mountain and foothill
streams from British Columbia to southern California, and eastward
through Idaho and Utah to Wyoming and Colorado. Larvae on sub-
merged wood and debris; adults usually on logs just above churning
or rushing water, either beneath or on the downstream side of the
log.
Lara avara amplipennis Darlington, 1929. Habitat as above from
British Columbia and Washington.
Lara gehring-L Darlington, 1929. Habitat as for L. avara from
Washington south to central California.
Genus Fhanooerus Sharp, 1882
PTwnooerus olavioornis Sharp, 1882. Rapids and riffles from Central
America and Mexico northward to Val Verde Co., Texas (known in the
United States from Devil's River and San Felipe Creek in Del Rio).
Larvae typically on submerged plant material; adults just above or
just below water line on objects protruding from water in rapids or
small falls.
13
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Tribe Elmini
Genus Ampumixis Sanderson, 1954
Ampumixis dispar (Fall, 1925). In sandy and gravelly bottoms of rapid,
clear, cool or cold streams in foothills and mountains from
Washington south to California.
Genus Aneyronyx Erichson, 1847
Ancyronyx variegata (Germar, 1824). On submerged wood or trash (larvae
may be under decaying bark) in streams throughout the eastern
states from Maine to Florida, westward to Wisconsin and the
eastern portions of Kansas, Oklahoma, and Texas. Sensitive to
sewage and industrial wastes.
Genus Atraotelmis Chandler, 1954
Atractelmis wawona Chandler, 1954. Rare in riffles of rapid, clear
mountain streams in California at elevations from 2,000 to 5,000
feet (actually reported from only two localities - the. South Fork
of the Merced River near Wawona in Yosemite National Park and
Middle Fork of Cottonwood Creek, Shasta County).
Genus Cleptelmis Sanderson, 1954
Cleptelmis addenda (Fall, 1907). On roots and moss or rocks and gravel
in rapid, cold mountain or foothill streams from California and
southeast Oregon to New Mexico and South Dakota.
Cleptelmis ornata (Schaeffer, 1911). On roots, moss, rocks, and gravel
in rapid mountain or foothill streams from central California to
British Columbia and eastward to Arizona, Colorado and Montana.
Genus Cylloepus Erichson, 1847
Cylloepus dbnormis (Horn, 1870) . Beneath rocks and in sandy gravel in
riffles of creeks and rivers throughout Mexico, but extending into
Arizona (San Pedro River) and Texas (Limpia Creek in the Davis
Mountains, small stream near Camp Wood). Common in Mexico (known
as Cylloepus sexualis Hinton) but rare in the United States.
Cylloepus parkeri Sanderson, 1953. Known only from small, rocky streams
in Bloody Basin, Yavapai Co., Arizona.
Genus Dubiraphia Sanderson, 1954
(This genus is currently under revision by Dr. William Hilsenhoff.
Some of these species may be combined. Others will be added.)
Dubivaphia bivittata (LeConte, 1852). On submerged roots, aquatic
plants, or other plant material in streams and lakes of eastern
states, and upper Mississippi River drainage.
14
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Dubiraphia brunneseens (Fall, 1925). Among submerged willow roots along
rocky, wave-washed shore of Clear Lake, Lake Co., California.
Dub-iraphia giulianii (Van Dyke, 1949). Described from vegetation and
rocks in the slow part of Russian River, California. Also reported
from eastern Oregon and southern Idaho.
Dubiraphia quadrinotata (Say, 1825). On submerged roots, aquatic plants,
or other plant material (including rocks encrusted with algae) in
streams, ponds, and lakes throughout the eastern and central states
where it is often abundant, and in scattered streams westward to
New Mexico, Utah, and Idaho. Sensitive to chlorides; occurs in
recovery zone below sewage treatment plants.
Dubiraphia vittata (Melsheimer, 1844). As above.
Genus Elsianus Sharp, 1882
(This genus is currently under revision by Dr. Howard Hinton.)
Elsianus•moestus (Horn, 1870). Beneath rocks in Arizona streams.
Elsianus shoemakei Brown, 1971. In gravel or beneath rocks in San
Felipe Creek in Del Rio, Texas and the upper Rio Salado in
Coahuila, Mexico.
Elsianus texanus Schaeffer, 1911. In gravel or under rocks in streams
with a high calcium content from Austin, Texas to southeastern New
Mexico and southward into Mexico.
Genus Gonielmis Sanderson, 1954
Gonielmis dietTiohi (Musgrave, 1933) . On submerged wood and roots in
sandy streams from eastern Tennessee, Georgia, and Florida to
Mississippi. Tolerant of moderate organic enrichment, turbidity,
and siltation, but sensitive to paper mill effluent.
Genus Heterelmis Sharp, 1882
(A new species is being described from the Santa Rita Mountains of
Arizona.)
Heterelmis gldb^a (Horn, 1870). On submerged wood and trash and under
stones, especially in lowland streams from southern Nevada,
through Arizona, much of Mexico, and in the Rio Grande River along
the Texas border.
Heterelmis obesa Sharp, 1882. On submerged wood and under stones in
cold, fast streams of Arizona and New Mexico, especially at higher
elevations.
Heterelmis vulnerata (LeConte, 1874). On submerged wood and debris
and under rocks in streams of Oklahoma and Texas.
Genus Heterlirmius Hinton, 1935
Heterlirmius oorpulentus (LeConte, 1874). In gravel and under rocks
in rapid mountain streams from New Mexico to California and
northward to South Dakota, Montana, and British Columbia.
15
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Heterlirmius koebelei (Martin, 1927) . In rapid mountain streams from
northern California to British Columbia.
Genus Hexacylloepus Hinton, 1940
Hexaoylloepus ferrugineus (Horn, 1870). On travertine, under rocks, in
gravel, and sometimes on wood, chiefly in riffles of streams with a
calcium content from Mexico through central Texas into the
Arbuckle Mountain region of south central Oklahoma and into south-
eastern New Mexico.
Genus Macronychus Muller, 1806
Macronychus glabratus Say, 1825. On submerged wood and debris in
streams of the eastern and central states from Florida to Maine and
eastern Texas and Oklahoma to Wisconsin. Sensitive to sewage and
many industrial wastes, such as those from plating, textile, and
viscose rayon plants.
Genus Microcylloepus Hinton, 1935
(Other species will soon be described, including one from springs
in Death Valley, California.)
Microcylloepus browni (Hatch, 1938). Warm spring in Montana.
Microcylloepus moapus La Rivers, 1949. Warm springs in southeastern
Nevada.
Microcylloepus moapus fraxinus La Rivers, 1949. Warm springs in
southeastern Nevada.
Microcylloepus pusillus (LeConte, 1852) . Versatile and common on sub-
merged wood and debris, under rocks, or in gravel of streams from
Mexico east to Florida, west to California, and north to Oregon,
Idaho, Wyoming, South Dakota, Missouri, Tennessee, and among the
eastern states to Maine. Tolerant of siltation and turbidity, but
sensitive to sewage and such industrial wastes as those from rayon
plants and plating mills.
Microcylloepus pusillus aptus (Musgrave, 1933) . Northern Florida to
Virginia.
Microcylloepus pusillus pusillus (LeConte, 1852). Virginia to New
York.
Microcylloepus pusillus lodingi (Musgrave, 1933). Southeastern (Gulf)
coastal plain.
Microcylloepus pusillus perditus (Musgrave, 1933). Peninsular Florida.
Microcylloepus pusillus similis (Horn, 1870). West of the Rocky Mountains.
Microcylloepus thermarum (Darlington, 1928). Warm springs in north-
western Nevada.
Genus Narpus Casey, 1893
(A new species will soon be described.)
Narpus angustus Casey, 1893. In gravelly or rocky rapids of clear
streams in the coastal range of California.
16
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Narpus arizonious (Brown, 1930). In rapid streams of the White Moun-
tains of eastern Arizona. (This may be but a variant of N. conoolor~)
Narpus oonoolov (LeConte, 1881). In clear, rapid, cool or cold streams
of western states from New Mexico to California and north into
Canada.
Genus Neooylloepus Brown, 1970
Neooylloepus boeseli Brown, 1970. In gravel and rocks of rapids in
Devil's River northwest of Del Rio, Texas and West Clear Creek east
of Camp Verde, Arizona.
Genus Neoelnris Musgrave, 1935
Neoelmis oaesa (LeConte, 1874). In gravel and under rocks in riffles of
clear streams with a high calcium content in south-central and south-
western Texas, the Arbuckle Mountain region of south-central Oklahoma
and southeastern New Mexico.
Genus Optioservus Sanderson, 1954
Opt-ioservus ampliatus (Fall, 1925). In riffles of gravelly or rocky,
clear streams from Virginia northward into Canada. Relatively
tolerant of sewage and chlorides.
Optioservus oanus Chandler, 1954. Known only from Chalone Creek in
Pinnacles National Monument of west central California.
Opt-ioservus cvyoph-ilus (Musgrave, 1932) . On moss-covered stones in
fast, spring-fed brooks of the Great Smoky Mountains.
Opt-ioservus divergens (LeConte, 1874). In gravelly or rocky riffles of
clear streams from New Mexico to California and north into Canada.
Optioservus fastid-itus (LeConte, 1850). In gravelly or rocky riffles or
on wood in fast streams in upper New York and from Michigan to
Minnesota.
Opt-ioservus immunis (Fall, 1925). In gravelly or rocky streams of
Connecticut, New Jersey, and Pennsylvania. (Records from Georgia
and Tennessee may represent 0. cryoph-ilus , which greatly resembles
0. •immunis') .
Optioservus oval-is (LeConte, 1863) . In gravel or among moss-covered
stones in clear, riffly streams from North Carolina north to Vermont
and west to Alabama and Ohio.
Optioservus ozarkens-is Collier, n. sp. (see page 13) (Fig. 83)
Type locality: Holotype, male, Roaring River State Park, Cassville,
Missouri. Collected 30 December 1968 by Joe E. Collier.
Location of Type: Holotype, male, Department of Entomology, Fisheries,
and Wildlife, University of Minnesota; four paratypes, Snow
Entomological Museum, University of Kansas, Lawrence, Kansas; ten
paratypes will be deposited in California Academy of Sciences
Collection.
17
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DIAGNOSIS: This species resembles Optioservus trivittatus (Fig. 81) in
appearance but is larger and has very different markings.
DESCRIPTION: Holotype male: Length 2.3 mm, width 1.2 mm; head and
thorax shiny black, scutellum ochreous; elytra fuscous brown with
yellow-orange markings; venter fuscous brown; entire body covered
with short depressed hairs which are much more abundant on ventral
surface.
Head: Black; maxillary palpi four-segmented; antennae testaceous,
eleven-segmented, length 0.5 mm, segment eleven twice as long as
nine or ten, segment three four-fifths as long as eleven, segments
one and two almost as wide as long.
Pronotum: Length 0.6 mm, width 0.8 mm; sides arcuately convergent
anteriorly, disc covered with Very shallow punctuations, basal sub-
lateral carinae 0.2 mm long extending anteriorly.
Elytra: (Fig. 83) Wider than thorax, widest near middle; length 1.7
mm, width 1.2 mm; strial punctures shallow, separated by distance
greater than their width; humeral spot reaching seventh stria and
extending to suture, then posteriorly two-thirds of way along
elytron; second elongate spot extending from just below middle
almost to apex of elytron.
Venter: Covered with heavy hydrofuge pubescence, especially on ab-
domen. Legs ochreous yellow throughout entire length.
DISTRIBUTION: Missouri
SPECIMENS EXAMINED: Holotype (male), four paratypes from Roaring River
State Park, Missouri, and ten paratypes from Big Spring State Park,
Missouri, taken June 1954, July 1954 and December 1968.
Optioservus pecosensis (Fall, 1907). In clear, cool or cold, gravelly
or rocky streams from New Mexico to California and north to Wyoming
and Washington (according to Collier). (May well be confused with
0. divergens.)
Optioservus quadrimaeulatus (Horn, 1870). In gravelly or rocky riffles
from Colorado west to California and North to Montana and British
Columbia.
Optioservus sandersoni Collier, n. sp. (see page 13) (Fig. 82)
Type locality: Washington Co., Arkansas, 16 June 1962; Lot No. 193.
Location of type: Holotype, male, and three paratypes, will be deposited
in Illinois Natural History Survey Collection.
DIAGNOSIS: This species resembles Optioservus trivittatus (Fig. 81) and
Optioservus ozarkensis (Fig. 83), but may be separated from all
other Optioservus by the two spots and one sutural vitta on each
elytron (Fig. 82). This type of marking has not been found on any
other Optioservus.
DESCRIPTION: Holotype male: Length 2.6 mm, width 1.3 mm; head and
thorax black with yellowish-grey pubescence; scutellum yellowish-
orange; elytron dark red-brown with yellowish-orange spots and
sutural vitta, striae not deeply punctured on elytron.
Head: Black; clypeus covered with greyish pubescence; maxillary
18
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palpi four-segmented, red-brown in color; labial palpi red-brown,
three-segmented; antennae eleven-segmented, reddish-yellow, first
three segments equal to length of next six.
Pronotum: Black; sparse yellowish pubescence; very shallow
punctures; sides very slightly converging toward apex from base,
carinae extending from base nearly to middle, parallel to lateral
margin of thorax.
Elytra: (Fig. 82) Dark red-brown; each elytron containing one
rounded humeral spot and one elongated apical spot with sutural
vitta extending from scutellum to apical third of elytra; spots
and vitta yellow-orange in color.
Venter: Epipleuron and most of thorax and abdomen covered with
short grey pubescence; legs reddish-yellow; most of underside just
slightly darker than legs in color.
Female: As for male.
DISTRIBUTION: Arkansas and Oklahoma.
SPECIMENS EXAMINED: Holotype (male), three paratypes from Washington
Co., Arkansas, four paratypes from Ottawa Co., Oklahoma, taken in
June 1930 and 1962.
Optioservus sexn-atus (LeConte, 1874). In gravelly or rocky riffles from
north coastal California to British Columbia and in scattered
localities in New Mexico, Utah, and Idaho.
Optiosewus triwittatus (Brown, 1930) . In gravel, under rocks, or on
wood in fast streams from the Great Smoky Mountains north to
Vermont and Quebec, and in Michigan and Wisconsin. Relatively
tolerant of sewage and chlorides.
Genus Ordobvevia Sanderson, 1953
Ovdobrevia nub-ifera (Fall, 1901). In gravel and under rocks of foot-
hill streams from California to Washington.
Genus Oulimnius Des Gozis, 1886
Oulimn-ius latiusoulus (LeConte, 1866). In gravel or under rocks in
riffles of clear streams (often very small brooks) from Alabama,
eastern Tennessee, and South Carolina northeast to Canada, ranging
from cool lowland streams to elevations higher than any of the other
local elmids.
Genus Promoresia Sanderson, 1954
Pvomoresia elegans (LeConte, 1852). In gravel and under rocks in
riffles of cool streams from the Great Smoky Mountains northeast to
lower New England. Promoresia is unusual among members of its sub-
family in that it often takes flight when removed from the water,
a feature which is characteristic of the Larinae and of Limnichidae
and Psephenidae.
PromoTesia tardefLa (Fall, 1925). In gravel and among moss and rocks of
riffles of cool streams in the Great Smoky Mountains and in New
England and eastern Canada.
19
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Genus Rhizelmis Chandler, 1954
Rhizelmis nigra Chandler, 1954. In fast, cool, shaded streams from 2,000
to 5,000 feet elevation in central and northern California.
Genus Stenelmis Dufour, 1835
(Several new species will soon be described; surprising records
have appeared from southern Idaho and from eastern Oregon.)
Stenelmis antennalis Sanderson, 1938. Commonly on submerged wood and
debris (especially under loose bark) in sandy southeastern streams
from Mississippi to Florida.
Stenelmis becmeri Sanderson, 1938. Cool, clear Ozark streams of
Arkansas, Missouri, and Oklahoma; also reported from central and
eastern Tennessee.
Stenelmis bicarinata LeConte, 1852. Gravelly or rocky streams from
Vermont to South Carolina, west to Wisconsin and Texas and south-
eastern New Mexico.
Stenelmis calida calida Chandler, 1949. In warm spring pool in southern
Nevada.
Stenelmis oalida moapa La Rivers, 1949. In warm streams of southern
Nevada.
Stenelmis conoinna Sanderson, 1938. In eastern streams from North
Carolina to Quebec.
Stenelmis oonvexula Sanderson, 1938. In sandy, gravelly or rocky streams,
often on submerged wood, from northwestern Florida west to Texas
and southern Oklahoma.
Stenelmis arenata (Say, 1824). In stream riffles from Alabama and
northwestern Florida northeastward to New Brunswick and westward to
Texas and Wisconsin. Tolerant of chlorides but sensitive to sew-
age and phosphate wastes.
Stenelmis decorata Sanderson, 1938. In streams from South Carolina to
Maryland and west to Kansas and Wisconsin. Tolerant of sewage and
phosphate wastes.
Stenelmis douglasensis Sanderson, 1938. On wood in lakes in Michigan
and Wisconsin.
Stenelmis exigua Sanderson, 1938. In clear streams of western Arkansas
and eastern Oklahoma.
Stenelmis exilis Sanderson, 1938. In clear streams of western Arkansas
and eastern Oklahoma.
Stenelmis fusoata Blatchley, 1925. From the sandy streams of northern
and central Florida to wave-washed lake margins in Lake Co. to
drainage canals of the Everglades.
Stenelmis grossa Sanderson, 1938. In sandy streams from Mississippi to
Texas and Arkansas, usually beneath sunken logs.
Stenelmis hwnerosa Motschulsky, 1859. In streams from Massachusetts
south to South Carolina and Tennessee.
Stenelmis hungerfordi Sanderson, 1938. Under rocks in fast streams (with
high calcium content) from northwestern Florida to South Carolina.
Stenelmis knobeli Sanderson, 1938. In streams of southwestern Arkansas.
Stenelmis lateralis Sanderson, 1938. In streams from Virginia and
Pennsylvania to northeastern Oklahoma.
20
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Stenelmis markeli Motschulsky, 1854. In streams from Massachusetts
south to Tennessee and west to Wisconsin and Oklahoma.
Stenelmis mera Sanderson, 1938. In streams from Quebec south to North
Carolina and west to Wisconsin and Arkansas.
Stenelmis mirabilis Sanderson, 1938. In eastern streams from
Connecticut to South Carolina.
Stenelmis musgravei Sanderson, 1938. In streams from New York to
South Carolina and west to Wisconsin and Texas.
Stenelmis parva Sanderson, 1938. In streams in southeastern Oklahoma
and eastern Texas.
Stenelmis quadrimaoulata Horn, 1870. In lakes and marl bogs from
Quebec to Maryland and west to Indiana and Michigan.
Stenelmis sandersoni Musgrave, 1940. In streams from Ontario and
West Virginia to northeastern Oklahoma.
Stenelmis sexlineata Sanderson, 1938. In streams from Tennessee and
Kentucky to Indiana, Kansas, Oklahoma, and Texas. Tolerant of
moderate pollution by sewage, phosphate, and a variety of wastes.
Stenelmis sinuata LeConte, 1852. In sandy streams from Florida to South
Carolina and west to Mississippi.
Stenelmis vittipennis Zimmerman, 1869. In streams from Quebec to South
Carolina and west to North Dakota and Kansas.
Genus Zaitzevia Champion, 1923
Zaitzevia parvula (Horn, 1870). Usually in gravel or under rocks in
fast mountain streams of western states from New Mexico to
California and north to South Dakota, Montana, and-British Columbia.
Zaitzevia thermae (Hatch, 1938). In warm springs of Montana. (Perhaps
this is only an ecological variant of Zaitzevia parvula.)
Family DRYOPIDAE (Erichson, 1847)
Genus Dry ops Olivier, 1791
Dryops arizonensis Schaeffer, 1905. Usually just above the water line
in debris caught on sticks or rocks in stream riffles (or taken at
lights) in central and southern Arizona.
In addition to this known distribution of Dryops in the United States,
we may expect the genus to occur in southeastern California, in New
Mexico, and in Texas along the Rio Grande (I have taken it just over the
border in Mexico). Furthermore Dryops viennensis (Heer, 1841), an acci-
dentally imported species from Europe, has become established in Quebec,
and is to be expected in Maine.
Genus Heliohus Erichson, 1847
Helichus basalis LeConte, 1852. Beneath rocks near the shore in streams
from Georgia to Massachusetts and west to Texas, Kansas, and Ohio.
21
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Helichus confluentus Hinton, 1935. On debris and beneath rocks usually
in upland or mountain streams of western Texas, New Mexico, and
Arizona, but with a disjunct population in the mountains of northern
Georgia (Rabun Bald).
Helichus fastigiatus (Say, 1824). Under rocks in streams from Florida
to Maine and Canada, west to Illinois, eastern Kansas and Oklahoma.
Helichus irmsi Hinton, 1937. On debris and under rocks in streams from
western Texas to California, often abundant.
Helichus lithophilus (Germar, 1824). Under stones or on submerged wood
in streams from Florida to Canada and west to Wisconsin, Iowa, cen-
tral Oklahoma and Texas.
Eeliohus productus LeConte, 1852. On debris and under rocks in valley
and foothill streams of central and southern California.
Helichus stviatus LeConte, 1852. On debris and under rocks in cool
streams from South Carolina to Quebec, west to California and
British Columbia.
Helichus striatus foveatus LeConte, 1852. On debris and under rocks in
western streams up to elevations well above 8,000 feet, from
Arizona and California to British Columbia.
Helichus suturalis LeConte, 1852. On debris and under rocks in all sorts
of streams from warm, muddy, lowland rivers to mountain brooks well
above 8,000 feet from central Oklahoma and Texas west to Utah and
California and south to Guatemala; often abundant and frequently the
only dryopoid in lowland southwestern streams.
Helichus triangularis Musgrave, 1935. On debris and under rocks in small
mountain streams from the Chisos and Davis Mountains of Texas to the
Chiricahua and Huachuca Mountains of Arizona.
Genus Pelonomus Erichson, 1847
Pelonomus obscurus LeConte, 1852. Not a "riffle" beetle. On aquatic
plants and debris in swamps and ponds (though most often taken at
lights) from Florida to Texas and north to Illinois.
Family LIMNICHIDAE (Thomson, 1860)
Subfamily Limnichinae
Genus Lirmichus Latreille, 1829
Many species have been described, but none are known to be aquatic,
although the adults may be found in damp places such as stream
margins throughout much of the United States.
Genus Lutrochus Erichson, 1847
Lutrochus arizonicus Brown and Murvosh, 1970. Larvae in calcareous en-
crustation of submerged rocks, etc.; adults usually at or just above
water line on the downstream side of rocks or wood projecting from
the water in riffles of streams in central Arizona.
Lutrochus laticeps Casey, 1893. Larvae and adults as above in streams
of high calcium content from Maryland to Michigan and eastern Oklahoma.
22
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Lutroohus luteus LeConte, 1852. Larvae in calcareous encrustation or be-
neath submerged rocks; adults either at water line or on submerged
rocks or wood in travertine or other streams with high calcium con-
tent from central Texas and Oklahoma to eastern New Mexico.
Genus Fhysemus LeConte, 1854
Physemus minutus LeConte, 1854. Not known to be aquatic, but adults may
be found in damp places such as stream margins in southwestern
states from Texas to California.
Subfamily Cephalobyrrhinae
Genus Thvoscinus LeConte, 1874
Not known to be aquatic; adults are intertidal (two species along
the Gulf shore of Texas and one species on the shores of southern
California).
Family PSEPHENIDAE (Lacordaire, 1854)
Subfamily Eubriinae
Genus Aaneus Horn, 1880
(This genus merits study. Few larvae have been taken.)
Acneus o^egonens'ls Fender, 1951. Larvae on or under submerged rocks,
adults along swift, rocky streams from Oregon to Olympic Peninsula
of Washington.
Acneus quadrimaoulatus Horn, 1880. Larvae on or under submerged rocks
in rapid sections of streams, but in pools of quiet water protected
by boulders; adults on vegetation or rocks along swift, rocky
streams in California and Oregon, at elevations up to about 4,000
feet.
Genus DioTonopselccphus Guerin-Meneville, 1861
DioTccnopselaphus vaviegatus Horn, 1880. The larva probably occurs on or
under submerged rocks or wood in streams; the adult near streams
from New York, Maryland, and Pennsylvania to Illinois. Rare. (No
one has reported the larva in the United States. It has probably
been mistaken for that of Eotopri-aj or simply overlooked.)
Genus Eatopr-ia LeConte, 1853
Eotopria nervosa (Melsheimer, 1844). Larvae on submerged rocks and wood
in streams from Florida to Maine and Canada west to Iowa, Missouri,
and Oklahoma; adults on vegetation along streams or taken at lights.
23
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Subfamily Eubrianacinae
Genus Eubrianax Kiesenwetter, 1874
Eubrianax edwardsi (LeConte, 1874). Larvae on or under submerged rocks
in California and Oregon streams up to about 6,000 feet; adults
along stream banks.
Subfamily Psepheninae
Genus Psephenus Haldeman, 1853
(Additional species from Arizona are under study. Murvosh and I are
describing two new species.)
Psephenus haldemani Horn, 1870. Larvae on or under submerged rocks in
streams, adults on rocks or wood protruding from riffles, at or
just above water line on downstream side; from California to British
Columbia and northern Idaho at elevations up to about 4,000 feet.
Psephenus herriak-i (DeKay, 1844) . Habitats as above; in streams from
central Alabama and Georgia northeast to Maine and Canada and west
to eastern Oklahoma, Kansas and Wisconsin, at elevations below 2,500
feet. Also on wave-washed shores with suitable rocks, as on the
Bass Islands of Lake Erie.
Psephenus murvoshi- Brown, 1970. Habitats as above, in streams of cen-
tral Arizona at elevations below 5,000 feet.
Psephenus texanus Brown and Arrington, 1967. Habitats as above, in
streams of central and southwestern Texas, at elevations below 2,000
feet. These streams are typically clear, with a high calcium content
Family PTILODACTYLIDAE (Lacordaire, 1857)
Genus Anchycte-is Horn, 1880
Anchyeteis velutina Horn, 1880. Larvae in springs and rapid streams of
northern California and adjacent Nevada; adults along or near
streams.
Genus Anohytarsus Guerin-Meneville, 1843
Anchytarsus 'b-icolov (Melsheimer, 1846). In or near streams from Georgia
to New York, rare.
Genus Stenooolus LeConte, 1853
Stenocolus scuteltaris LeConte, 1853. Along streams of central
California at elevations up to 4,000 feet.
24
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SECTION III
KEY TO AQUATIC GENERA AND SPECIES OF ADULT DRYOPOID BEETLES
OF THE UNITED STATES
Compact, ovoid; head retracted within prothorax and invisible
from dorsal view, antennae fitting into grooves of
prosternum; tarsus with third segment lobed; claws not
prominent; not genuinely aquatic (Fig. 16):
CHELONARIIDAE, Chelonarium lecontei
Head usually visible from dorsal view, though it may be
temporarily retracted within prothorax; third segment of
tarsus not conspicuously lobed; tarsal claws prominent .... 2
Fig. 16- Chelonapi-wn leoontei. adult, dorsal.
2(1) Typically hard-bodied; front coxae rounded or transverse 3
Typically soft-bodied; front coxae exserted and projecting
and/or hind margin or pronotum crenulate 5
3(2) Typically very plump, convex, and ovoid; legs retractile;
apical segment of tarsus shorter than remaining segments
combined; middle coxae widely separated, hind coxae close
together LIMNICHIDAE 105
Usually more elongate; legs not retractile; apical segment
of tarsus usually as long as other four segments combined,
with large claws; if middle coxae are widely separate, so
are hind coxae 4
4(3) Anterior coxae typically globular and without exposed
trochantin; antennae typically slender, not forming a
pectinate or lamellate club; female genitalia symmetrical,
with jointed, movable styli (Fig. 11); about 1-8 mm long,
usually less than 4 mm ... .ELMIDAE 6
Anterior coxae transverse and with exposed trochantin;
antennae usually short, with apical segments pectinate or
lamellate and forming a club; female genitalia without
styli, usually asymmetrical and resembling two knife
blades (Figs 101, 102), functioning as ovipositors; about
4-8 mm long ^.DRYOPIDAE 94
25
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5 (2)
6 (4)
7 (6)
Rather broad and depressed; mandibles typically concealed;
labrum usually not visible from in front ..PSEPHENIDAE... 110
Body relatively elongate; mandibles visible; labrum usually
visible from in front PTILODACTYLIDAE 118
Riparian, usually not under water; agile fliers; rather
soft-bodied; pubescent, but without tomentum; procoxae
transverse and with trochantin exposed LARINI
Aquatic; typically slow-moving, clinging to submerged
objects; rarely flying except at night; hard-bodied;
with tomentum on various ventral parts; procoxae
rounded and trochantin concealed ELMINI
10
Less than 4 mm long; antennae clubbed; pronotum with sub-
lateral sulci (Fig. 17): Phanooerus olawieomis
More than 5 mm long; black, antennae not clubbed; pronotum
without sublateral sulci (Fig. 18) Lara 8
Figs 17-18 Dorsal view of adult: 17- Phanoeerus clawicornis;
18- Lara avara.
8 (7) From 5.5-6.5 mm long; pronotum with hind angles acute but
scarcely more prominent than middle lobes; elytral
pubescence uniform (Fig. 19): Lara gekr-ingi,
From 6.8-8.1 mm long; pronotum with hind angles acute and
prominent; alternate elytral intervals with the pubescence
decumbent, so that the elytra appear dark with sericeous
lines 9
9 (8) Elytra 6.0-6.5 mm long; elytra wider in proportion to
pronotum; pronotum with more prominent angles (Fig. 21):
Lara avara amplipennis
Elytra about 5.2-5.5 mm long; elytra narrower in propor-
tion to pronotum; pronotal angles less prominent (Fig. 20):
Lara avara avara
26
-------
Figs 19-21 Pronotum and elytra: 19- Lara gehringi; 20- Lara
avara avara; 21- Lara avara amplipennis (all from Darlington,
1929)
10 (6) Hind coxae globular and about same size as other coxae;
posterior margin of prosternal process almost as wide
as head; on wood 11
Hind coxae transverse and larger than other coxae;
posterior margin of prosternal process much narrower
than width of head; often on rocks or in gravel 12
11 (10) Black; elytra with sublateral carinae; antennae with 7
segments, enlarged at apex; pronotum without transverse
impressions; 2.5-3.5 mm long (Fig. 22): Maeronychus glabratus
Conspicuously colored with black and yellow or orange;
elytra and pronotum without sublateral carinae;
antennae with 11 segments, filiform; pronotum with
oblique transverse impressions at apical third; tarsal
claw with a basal tooth; 2.1-2.6 mm long (Fig. 23):
Anoyronyx variegata
Figs 22-23 Dorsal view of adult: 22- Maoronyohus glabratus;
23- Anoyronyx vari-egata.
27
-------
12 (10)
13 (12)
14 (12)
Antennae with 8 segments, the apical one being enlarged;
pronotum with median longitudinal groove; elytra with
3 sublateral carinae Zaitzevia I3
Antennae with 10 or 11 segments, usually filiform 14
In cold mountain streams; 2-2.5 mm long, 0.8-1 mm wide
(Fig. 24): Za-itzev-ia parvula
In a warm spring near Bozeman, Montana; 2 mm long, 0.7 mm
wide: Za-itzevia thermae
Anterior tibia with fringe of tomentum (Fig. 2) 43
Anterior tibia without fringe of tomentum 15
Figs 24-25 Dorsal view of adult: 24- Zaitzevia parvula; 25- Ordobrewia
nubifera.
15 (14) Elytron with an accessory stria (sutural stria confluent
with second stria at about fifth puncture); granules of
head and legs elongate; 2.2-2.4 mm (Fig. 25):
OTdobrevia mibifera
Elytron without such an accessory stria; granules of head
and legs round (Fig. 26) Stenelmis 16
(This section is adapted from Sanderson (1938). In identi-
fication of species it will be helpful to know that in most
males the inner surface of the middle tibia bears a swelling
or row of spinules as shown in Fig. 26.)
16 (15) From thermal waters in southern Nevada; elytra immaculate
(S. a. cal-lda) or faintly trivittate (S. o. moccpa);
wings reduced and non-functional; body covered with
dense, matted, greenish gray pile; antennae and palps
testaceous; aedeagus quite similar to that of S. fusoata;
3-3.6 mm long, 1-1.25 mm wide: Stenelmis eal'ida
From east of the Rocky Mountains 17
28
-------
Fig. 26- Stenelnris erenata adult showing appearance of middle
tibia of female on the left and of the male on the right (to
illustrate means of distinguishing sexes if genitalia are not
visible).
17 (16) Last tarsal segment distinctly longer than the other four
combined, the last segment usually suddenly dilated
beyond the middle (Fig. 27); tarsal claws relatively robust
(Fig. 28) Humerosa-sinuata group 28
Last tarsal segment not distinctly longer than the other
four combined, the last segment not as noticeably
dilated (Fig. 29); tarsal claws relatively slender
(Fig. 30) Cvenata group 18
Figs 27-35 Tarsus of Stenelmis species: 27- Apical
segment of S. wLtti,penni,s; 28- S. markeli; 29- Apical
segment of S. sandersoni; 30- S. lateralis. Aedeagus (male
genitalia) of Stenelmis species: 31- S. sexlineatas dorsal
aspect; 32- S. arenata; 33- S. exigua; 34- S. beameri;
35- S. lateralis (all from Sanderson).
29
-------
18 (17) Each elytron with 3 longitudinal vittae; 3.2-3.6 mm long,
1.25-1.4 mm wide (Fig. 31): Stenelmis sexlineata
Each elytron with no more than one vitta or elytron
bimaculate 19
19 (18) Humeral spot or vitta embracing umbone of elytron 22
Humeral spot or vitta on inside of sixth interval 20
20 (19) Body very robust, and with the elytral spots or stripe
wider, covering considerably more than the fifth
interval; third interval sharply elevated at base;
elytron with entire vitta or bimaculate; 3.0-3.35 mm
long, 1.2-1.35 mm wide (Figs 26, 32): Stenelmis orenata
Body very elongate, with the elytral spots or stripe
narrower, covering but little more than the fifth
interval; third interval but slightly elevated at base
and this elevation very short 21
21 (20) Median lobe of aedeagus distinctly constricted at middle
(Fig. 33); 2.85-2.9 mm long, 1-1.1 mm wide: Stenelmis exigua
Median lobe of aedeagus more nearly parallel (Fig. 34);
3.2-3.4 mm long, 1.2-1.25 mm wide: Stenelmis beameri
22 (19) Vitta very broad and covering nearly all of the space
between the first and sixth intervals; 2.65-3 mm
long, 0.95-1.1 mm wide (Fig. 35): Stenelmis lateralis
Vitta narrower and never extending medially beyond the
second or third interval 23
23 (22) Size larger: 3.2-3.6 mm; lower margin of last tarsal
segment with a conspicuous angular process (Fig. 29) .... 24
Size smaller: 2.6-3.25 mm; lower margin of last tarsal
segment without such a process (Fig. 27) 25
24 (23) Apical abdominal emargination equal to width of last
tarsal segment; tibiae testaceous only at base; elytron
bimaculate; 3.3-3.6 mm long, 1.3-1.5 mm wide:
Stenelmis oonoinna
Apical emargination very inconspicuous and much less
than width of last tarsal segment; tibiae and apices of
femora testaceous; bimaculate; 3.2-3.5 mm long, 1.25-
1.5 mm wide (Fig. 37): Stenelmis sandersoni
25 (23) Basal tubercle of pronotum elongate and carinate 26
Basal tubercle of pronotum only slightly elongate
and never carinate 27
30
-------
V
41
Figs 36-41 Aedeagus of Stenelmis species: 36- S. conoinna;
37- S. sandersoni; 38- S. mera; 39- S. knobeli; 40- S. biaarinata;
41- 5. douglasensis (all from Sanderson).
26 (25) Legs testaceous; elytra twice as long as body width;
elytron bimaculate; 2.8-3 mm long, 1-1.1 mm wide:
Stenelmis exilis
Legs entirely or partially dark; elytra less than twice
as long as wide; elytron vittate but with vitta clouded
at middle; 2.6-2.85 mm long, 1-1.2 mm wide (Fig. 38):
Stenelmis mera
27 (25) Each elytron distinctly bimaculate; 2.75-3 mm long,
1-1.05 mm wide (Fig. 39): Stenelmis knobeli
Each elytron with an entire vitta; 2.8-3.25 mm long,
1.1-1.25 mm wide (Fig. 40): Stenelmis bioarinata
28 (17) Femora distinctly granulate 30
Femora punctulate, not at all granulate 29
29 (28) Elytral vitta complete from base to apex; lateral
processes on median lobe of aedeagus evenly rounded
(Fig. 41); 3.35-3.6 mm long, 1.2-1.5 mm wide:
Stenelmis douglasensis
Elytron distinctly bimaculate; processes on median
lobe of aedeagus subangulate anteriorly (Fig. 42);
3.25-3.6 mm long, 1.25-1-.4 mm wide: Stenelmis grossa
30 (28) Elytra immaculate -. 31
Elytra maculate or vittate 33
31 (30) Smaller (less than 2.7 mm); median band of head as
wide as two lateral ones combined; 2.3-2.7 mm long,
0.7-0.9 mm wide (Fig. 43): Stenelmis parva
Larger (over 2.7 mm long and 1 mm wide); median band
of head but little wider than either lateral band 32
31
-------
45 46
Figs 42-48 Aedeagus of Stenelmis species: 42- S. grossa;
43- S. parva; 44- S. fuscata; 45- S. hungerfordi; 46- 5. humerosa;
47- S, mirabilis; 48- 5. antennalis (all from Sanderson).
32 (31)
33 (30)
34 (33)
35 (33)
36 (35)
Lateral processes on penis (median lobe of aedeagus)
present and distinct (Fig. 44); 3.25-3.4 mm long,
1.15-1.25 mm wide: Stenelmis fuscata
Lateral processes of median lobe very inconspicuous
(Fig. 45); 2.7-2.8 mm long, 1-1.1 mm wide:
Stenelmis hung erfordi
Humeral spot or vitta distinctly embracing umbone 34
Humeral spot or vitta on inside of sixth interval 35
Femora and tibiae entirely gray; elytral vitta usually
entire, though somewhat clouded at middle; palpi
testaceous; 2.3-2.7 mm long, 0.95-1.1 mm wide
(Fig. 46): Stenelmis humerosa
Femora gray, tibiae testaceous; elytron distinctly
bimaculate; palpi dark brown to black; 2.7-2.9 mm
long,1.1-1.12 mm wide (Fig. 47): Stenelmis mirabilis
Antennae and palpi testaceous
Antennae or palpi, or both, dark brown to black
38
36
Palpi testaceous; last 6 or 7 segments of antenna
shining black; elytron bimaculate; 2.5-2.7 mm long,
1 mm wide (Fig. 48): Stenelmis antennalis
Palpi usually dark brown to black, the antennae usually
lighter 37
32
-------
37 (36) Lateral processes about one third the width of median
lobe (Fig. 49); elytron usually distinctly bimaculate,
but occasionally vitta is entire; 2.4-2.65 mm long;
0.95-1.05 mm wide: Stenelmis musgravei
Lateral processes about two thirds the width of median, lobe
(Fig. 50); elytron distinctly bimaculate; 2.7-3.2 mm long,
1.1-1.25 mm wide: Stenelmis quadrimaaulata
49
Figs 49-54 Aedeagus of Stenelmis species: 49- S. musgrauei;
50- S. quadrimaculata; 51- S. deoorata; 52- S. vittipennis;
53- S. aonvexula; 54- S. markeli (all from Sanderson).
38 (35) Sides of pronotum in anterior third divergent, the
apical angles subtruncate instead of acute; elytron
maculate, with vitta narrow and occupying little
more than fifth interval; lateral processes of
penis resembling those of S. hwnerosa; 3.2-3.45 mm
long, 1.2-1.35 mm wide: Stenelmis sinuata
Sides of pronotum in anterior third parallel or
convergent 39
39 (38) Lateral processes of median lobe of aedeagus present
and conspicuous 41
Lateral processes of median lobe absent or very
inconspicuous 40
40 (39) Elytral stripe entire; median lobe of aedeagus without
lateral processes (Fig. 51); 2.87-3 mm long, 1.1-1.15
mm wide: Stenelmis decorata
Elytron immaculate or with small, faint humeral and
apical spots; median lobe of aedeagus with narrow and
inconspicuous lateral processes (Fig. 45); 2.7-2.8 mm
long, 1-1.1 mm wide: Stenelmis hungerfordi
41 (39) Lateral processes of median lobe of aedeagus subangulate
anteriorly (Fig. 52); elytron with vitta entire; 3-3.4
mm long, 1.1-1.35 mm wide: Stenelmis vittipennis
Processes of median lobe evenly rounded 42
33
-------
42 (41) Lateral processes of penis as wide as parameres near
apex (Fig. 53); body more convex; elytron usually
with very faint humeral and apical spots; middle tibia
of male without the enlargement or spiny ridge on
inner side which is typical of most species of
Stenelnris; 2.75-3.1 mm long, 1.1-1.12 mm wide:
Stenelmls oonvexula
Lateral process of penis about half the width of
paramere near apex (Fig. 54); body less convex;
elytron with vitta entire, though slightly narrowed
at middle; 3-3.25 mm long, 1.17-1.3 mm wide:
Stenelmls mcacke'i-i
43 (14) Lateral margin of fourth or fifth abdominal sternite
produced as a prominent lobe or tooth which is bent
upward to clasp the epipleuron; epipleuron widened to
receive tooth, then usually narrowing abruptly toward
apex \ 56
Lateral margin of abdominal sternites not produced into
a prominent upturned tooth; epipleuron usually tapering
uniformly toward apex 44
44 (43) Pronotum with sublateral carinae 45
Pronotum smooth, without sublateral carinae 49
45 (44) Prosternum projecting beneath head; epipleuron extending
to middle of fifth abdominal segment; black; 2.5-2.6
mm long, 1.2-1.3 mm wide (Figs 55, 56): Rhizelmis nigra
Prosternum not projecting beneath head; epipleuron ending
at base of fifth abdominal segment; less than 2.3 mm
long 46
Figs 55-~56 Rhizelmis nigra adult: 55- dorsal; 56- ventral,
34
-------
46 (45)
47 (46)
Pronotal carinae forked at base (Fig. 57) .. Cleptelmis
Pronotal carinae not forked
47
48
Elytra immaculate and black (humeral angle may be
paler); 1.7-2.3 mm long, 1-1.2 mm wide: Cleptelm'is addenda
Elytra black with humeral and subapical red spot;
1.8-2.2 mm long, 1-1.2 mm wide (Fig. 57): Cleptelmis omata
Fig. 57- Clep-belmLs ocnata adult, dorsal.
48 (46) Sides of pronotum converging from base; body rather
spindle-shaped; black, each elytron with a broad
humeral and an oblique, narrow subapical spot; tarsi
and claws prominent; 2 mm long, 0.9 mm wide (Figs
58, 59) : AtTao~telmis wawona
Sides of pronotum parallel or divergent at base,
strongly convergent apically; hump-backed; black,
elytra black to red, uniformly colored or with basal
half red, with or without broad apical red spots; tarsi
and claws not unusually prominent; 1.8-2.2 mm long,
1.1-1.2 mm wide (Fig. 60): Ampum-Lxis dispar
49 (44) Maxillary palpi 3-segmented; markings, if present,
transverse (Fig. 61) Narpus 50
Maxillary palpi 4-segmented; markings, if present,
longitudinal (Fig. 62) Dubiraphia 52
50 (49) Slender, more than two and one half times as long as
wide; 3-4 mm long, 1.1-1.4 mm wide; sides almost
parallel; black: Narpus angustus
Relatively plump, less than two and one half times as
long as wide; sides convex 51
35
-------
Figs 58-59 Atractelnris wawona adult: 58- dorsal;
59- ventral.
Figs 60-61 Dorsal view of adult: 60- Anpumix-is
dispar; 61- Narpus eonooloT,
51 (50) Uniformly black with bronze luster; pronotal punctures
at middle separate by little more than their own
diameters; 3.4 mm long, 1.4 mm wide: Narpus axn,zonicus
Elytra black to red, usually with black band across
middle; pronotal punctures at middle separated by
twice their own diameters; 3.2-4.2 mm long, 1.4-1.9
mm wide (Fig. 61): Narpus conooloT
52 (49) Large (2.6-3.3 mm long, 1-1.2 mm wide); eastern;
elytron black, with broad testaceous vitta; pronotum
darker testaceous : Dubirap'hia biv-ittata
Smaller (1.7-2.5 mm long, 0.65-0.85 mm wide);
eastern or western 53
36
-------
53 (52) West of the Rocky Mountains (continental divide) 54
East of the Rocky Mountains (continental divide) 55
54 (53) Elytron dark brown, with at most faint yellowish
humeral or subapical spots; 1.8-2.5 mm long:
Dubirap'h'ia brunnesoens
Elytron black with humeral and apical light yellow
spots, sometimes united to form a vitta; 2.1-2.3 mm
long: Dubiraph-ia giulianii
55 (53) Black, elytron with humeral and apical rufous or
testaceous spots, which may be united to form a
vitta; 1.7-2.5 mm long, 0.65-0.85 mm wide (Fig. 62):
Dubirccph-ia quadrinotata
Brownish, elytron with a broad testaceous vitta;
1.8-2.5 mm long, 0.7-0.85 mm wide: Dub-iraph-ia wittata
56 (43) Tooth which clasps epipleuron arising from lateral margin
of fifth abdominal sternite 57
Tooth which clasps epipleuron arising from apical
(posterior) lateral margin of fourth abdominal
sternite 76
63 x
Figs 62-63 Dorsal view of adult: 62- Dubiraphia quadrinotata;
63- Elsianus texanus.
57 (56) Elytron at base with a short accessory stria between
sutural and second major striae (Fig. 63); testis
trilobate Elsianus
Elytron without such an accessory stria, testis
usually bilobate
58
60
37
-------
58 (57) Small (3.1-3.8 mm long, 1.2-1.5 mm wide); black, with
antennae and tarsi rufous, palp rufo-testaceous; penis
extending beyond apices of parameres more than one
third the length of parameres: Elsianus shoemakei-
Larger (over 4 mm long); penis extending beyond apices of
parameres less than one quarter the length of the
parameres 59
59 (58) In Arizona; rufous to black; 4-5.2 mm long, 1.7-2.1 mm
wide (it may be that more than a single species is
represented by these measurements; very few specimens
have been taken) : Els-ianus moestus
In Texas and eastern New Mexico; rufous to black; 4-5.4
mm long, 1.7-2 mm wide (Fig. 63) (further study may
reveal this species to be synonymous with E. moestus} :
Els-ianus texanus
60 (57) Elytron with one sublateral carina; pronotum without
oblique sculpturing 61
Elytron with two sublateral carinae (rarely only one in
Mi.orooylloepus, which has oblique sculpturing on
posterior half of pronotum) 62
61 (60) Posterior half of pronotum divided by a conspicuous
median longitudinal impression; pronotum with a
transverse impression slightly anterior to middle;
brown to black; 2.6-3.3 mm long, 1-1.2 mm wide (Fig. 64):
Neooylloepus boeseli-
Pronotum undivided except by transverse impression at
anterior two-fifths; testaceous; 1.5-1.7 mm long, 0.5-
0.6 mm wide (Fig. 65): Neoelmis oaesa
Figs 64-65 Dorsal view of adult: 64- Neoaylloepus boeseli;
65- Neoelmis oaesa.
38
-------
62 (60)
63 (62)
64 (63)
Hypomeron of pronotum with a belt of tomentum extend-
ing from coxa to lateral margin; pronotum with a
shallow median longitudinal impression but with no
transverse impressions; testaceous to black; 1.7-2.1
mm long, 0.7-0.85 mm wide (Fig. 66):
HexaayI toepus fevrugineus
Hypomeron with or without tomentum, but if present it
does not reach lateral margin 63
Prosternal process broad and truncate; pronotum without
median longitudinal impression, usually with transverse
impression at middle; pronotal hypomeron with tomentum
near coxa; body usually plump; mandible with a lateral
lobe (Fig. 5) Hetevelvris 64
Prosternal process relatively narrow, elongate with
apex, tapering or rounded; pronotum with median
longitudinal impression; hypomeron without tomentum;
body not plump 66
Basal segment of each tarsus with two closely appressed,
short, stout spines on inner apex; reddish brown to
black; pronotum with little or no transverse impression
at middle; 2.5-3.3 mm long, 1.1-1.5 mm wide:
Heterelmis obesa
Basal segment of tarsus without such spines on inner
apex; pronotum with transverse impression at middle;
less than 2.5 mm long 65
Figs 66-67 Dorsal view of adult: 66- Hexaoylloepus feTTug-ineus;
67- Heterelmis vulnerata.
65 (64) Medial surface of parameres of aedeagus bearing, a row of
delicate hairs; brown to black; 1.9-2.2 mm long, 1-
1.1 mm wide: Heterelm-is gldbra
Medial surface of parameres devoid of hairs; brown to
black; 1.8-2.35 mm long, 0.9-1.15 mm wide (Fig. 67):
Heterelmis vulnerata
39
-------
66 (63)
67 (66)
Pronotum with a transverse impression at anterior two-
fifths; mandible with a lateral lobe as in Fig. 5;
epipleuron without tomentum; small, less than 2.3 mm
long (Fig. 70) M-ieroGylloepus
Pronotum without such a transverse impression; mandible
without a lateral lobe; epipleuron with tomentum;
larger, at least 2.3 mm long (Fig. 68) Cylloepus .
68
67
Pronotum wider than long; fifth elytral interval not
carinate; metastemum with a short carina at middle
near posterior margin; black, elytron usually with two
large reddish spots; 2.3-3 mm long; 1.2 mm wide (Figs
68, 69) : Cylloepus parkeri
Pronotum slightly longer than wide; fifth elytral interval
partly carinate; metasternum depressed but without a
posterior median carina; reddish brown to black; 3.5-
4.3 mm long, 1.5-1.65 mm wide: Cylloepus abnormis
68 (66)
69 (68)
Figs 68-69 Cylloepus parkevi, adult: 68- dorsal; 69- ventral.
Pronotum longer than wide; wing usually reduced,
shorter than elytron; from warm springs 69
Pronotum usually wider than long; wing functional,
when extended longer than elytron; 1.65-2.2 mm long,
0.68-0.9 mm wide (Fig. 70)... Miorocylloepus pusillus... 72
Elytron with 1 sublateral carina; elytra only slightly
wider than pronotum; sculpturing of pronotum reduced;
black; 1.4-1.7 mm long, 0.5 mm wide; from warm spring in
northwestern Nevada: M-ioTocylloepus thermapum
Elytron with 2 sublateral carinae; elytra distinctly
wider than pronotum; reddish to black 70
40
-------
71
Figs 70-71 Dorsal view of adult: 70- Miovooylloepus pusillus;
71-Oulimnius latiusoulus.
70 (69) From warm springs in Montana (near Bozeman)> black; 2 mm
long, 0.68-0.7 mm wide: Microeylloepus browni
From warm springs in southeastern Nevada; reddish black,
1.7-1.9 mm long, 0.7-0.8 mm wide. Mierocylloepus mo opus. 71
71 (70) Wing greatly reduced, not exceeding one-third of
abdominal length: Mioicooylloepus moapus moapus
Wing less reduced, slightly over half of abdominal
length: Miarooylloepus moapus fraxinus
72 (68) Elytron reddish to black, without distinct markings 73
Elytron with vitta or spots 74
73 (72) In western states: Mieroeylloepus pusillus similis
In southeastern Gulf coastal plain:
Miarooylloepus pusillus lodingi
74 (72) Elytron with a vitta: Miovooylloepus pusillus aptus
Elytron with spots 75
75 (74) Elytron with humeral and apical spots:
Mi,o?ooyl1oepus pusillus pusillus
Elytron with only humeral spot:
Mieroeylloepus pusillus perditus
76 (56) Pronotum with sublateral carina extending from base to
anterior margin; elytron with 3 sublateral carinae;
brown to black; 1.25-1.6 mm long, 0.65-0.8 mm wide
(Fig. 71): Oulimnius latiusaulus
Pronotum with sublateral carina absent or not extending
beyond about middle; elytron without sublateral
carinae; larger species, longer than 1.6 mm 77
41
-------
77 (76) Pronotum smooth, without or with only a trace of
carinae; body elongate and spindle-shaped; black,
elytron with two oblique yellowish spots; legs long,
claws prominent and recurved; 2-2.6 mm long, 0.95-
1.1 mm wide (Fig. 72): Gonielmis dietrichi
Pronotum with short sublateral carinae 78
Figs 72-73 Dorsal view of adult: 72- Gonielmis dietriohi;
73- PromoTesia elegans.
78 (77) Body rather elongate; tarsi and claws long and prominent;
lateral and posterior margins of pronotum smooth;
eastern (Fig. 73) Promoresia 79
Body plump; tarsi and claws not conspicuously enlarged;
lateral margin of pronotum usually slightly serrate,
posterior margin usually with many small, closely-
placed teeth 80
79 (78) Black, elytron bimaculate, both spots very elongate and
oblique, the anterior spot extending from the humerus
posteromedially to second stria and terminating acutely
near middle of elytron, the posterior spot extending
from near middle of elytron (lateral to apex of
anterior spot) posteromedially almost to sutural
interval and apex of elytron; 2.1-2.4 mm long, 0.9-1 mm
wide (Fig. 73): PTomoresia elegans
Black, elytron bimaculate, the anterior spot broadly rounded,
extending posteriorly no more than one third of elytral
length; subapical spot elongate and oblique, but shorter
than in previous species; 2-2.4 mm long, 0.9-1.1 nun wide:
Promoresia toy delta
42
-------
80 (78) Convex, giving a rather hump-backed appearance, with
sutural intervals slightly raised; with third or
fourth elytral stria converging and merging with
second or third stria at about apical third; major
striae entire, extending to apex of elytron; antennae
with 10 or 11 segments, last 3 somewhat enlarged; apex of
fifth abdominal sternite usually somewhat truncate
or emarginate; tarsal claws relatively slender; in
western mountains (Fig. 74) Heterlirmius 81
Less convex; sutural interval usually not raised;
elytral striae not ordinarily merging as described
above, either being entire or becoming obsolete in
posterior portion of elytron; antennae with 11 segments,
the last 3 less enlarged; apex of fifth abdominal
sternite usually evenly rounded; claws somewhat
larger and more curved (Fig. 75) .... Optiosewus
[This section is largely based upon Collier (1969).].... 82
81 (80)
82 (80)
Figs 74-75 Dorsal view of adult: 74- Heteylimnius
oonrpulentus; 75- Opt-ioservus ovalis.
Antenna with 11 segments; pronotum black; elytron
reddish to black, often reddish or yellowish in
basal half shading to brown or black and with a
diffuse lighter spot apically; 2-2.5 mm long, 1.1-
1.3 mm wi e (Fig. 76): Heterl-Lrmius koebelei
Antenna with 10 segments; pronotum black; elytron
brown to black, often reddish at base and in a
rather faint apical spot; 2.4-2.9 mm long, 1.25-
. 1.45 mm wide (Fig. 74): Hetevl-imnius oorpulentus
Elytra immaculate, with no vittae or spots
Elytra with vittae and/or spots
83
86
43
-------
83 (82) Small, 2-2.1 mm long, 1 mm wide; slightly humped in
side view; brown to black; eastern (Fig. 77):
Optioservus cryophilus
Larger, at least 2.2 mm long; not noticeably humped
in side view 84
84 (83)
85 (84)
86 (82)
87 (86)
88 (87)
Figs 76-82 Outline of adult pronotum and elytron:
76- Heterlirmius koebetei; 77- Optioservus cryophilus;
78- <9, immunis; 79- 0* divevgens; 80- 0. pecosensis;
81- 0. trivittatus; 82- 0. sandersoni (all from Collier).
Eastern; strial punctures on elytra deep; 2.2-2.4 mm
long, 1.2-1.3 mm wide; brown to black (Fig. 78):
Optioservus immunis
Western 85
Penis tapering gradually to a subacute apex; elytral
striae lightly punctured; brown to black, with elytra
at times lighter than head and thorax; 2.2-2.5 mm
long, 1-1.1 mm wide (Fig.79): Optioservus divergens
Penis more finger-shaped, tapering abruptly to a
rounded apex; strial punctures deeper; uniformly
shiny black; 2.4-2.6 mm long, 1-1.2 mm wide (Fig. 80):
Optioservus pecosensis
Elytron with sutural vitta extending to apical third
Elytron without sutural vitta
87
89
Elytron also with yellow vitta from humerus almost to
apex (Fig. 81), 1.65-2.1 mm long, 0.9-1.1 mm wide:
Optioservus trivittatus
Without humeral vitta 88
Sutural vitta narrow; humeral spot discrete; apical
spot long and narrow, subvittate (Fig. 82); 2.6 mm
long, 1.3 mm wide: Optioservus sandersoni
Sutural vitta broadened'anteriorly and combined with
humeral spot, apical spot elongate (Fig. 83); 2.3
mm
long, 1.2 mm wide:
Optioservus ozarkensis
44
-------
89 (86)
90 (89)
91 (90)
Elytron bimaculate 92
Elytron with an elongate humeral spot or with a
vitta extending from humerus almost to apex 90
Large, 2.8-3.1 mm long, 1.4-1.5 mm wide; elytral
vitta extending almost to apex, at times bright
yellow; pronotal carinae rather short and feeble
(Fig. 84): Optioservus fastiditus
Smaller- less than 2.7 mm long; pronotal carinae
well developed and extending at least to basal third.... 91
In far west; elytron with elongate humeral spot or
short vitta (Fig. 85); elytra with grizzled appearance
due to long golden hairs; 2.1-2.5 mm long, 0.9-1.4 mm
wide: Optioservus oanus
Eastern; elytron with vitta from humerus almost to
apex (Fig. 86); not grizzled; 2.3-2.6 mm long,
1.2-1.3 mm wide: Optioservus ampliatus
Figs 83-89 Outline of adult pronotum and elytron of Optioservus
species: 83- 0. ozarkensis; 84- 0. fastiditus; 85- 0. canus;
86- 0. ampliatus; 87- 0. ovalis; 88- 0. quadrimaaulatus;
89- 0. seriatus (all from Collier).
92 (89) Eastern; elytral spots almost forming a vitta in some
specimens (Figs 75, 87); 2.4-2.6 mm long, 1.2-1.4 mm
wide: Optioservus ovalis
Western; elytral spots widely separated 93
93 (92) Relatively broad, elytra noticeably wider than pronotum;
humeral spot larger; usually reaching second stria
(Fig. 88); 1.8-2.2 mm long, 1-1.1 mm wide:
Optioservus quadrimaaulatus
More elongate, elytra scarcely wider than pronotum;
humeral spot narrower, usually not reaching medially
beyond third stria (Fig. 89); 1.8-2.2 mm long, 0.8-
0.9 mm wide: Optioservus seriatus
45
-------
94 (4) Pronotum on each side with a conspicuous, complete
sublateral longitudinal sulcus; pubescent; brown;
about 4.5 mm long, 1.75 mm wide (Fig. 90):Dryops arisonensis
Pronotum without such a sublateral sulcus 95
Figs 90-91 Dorsal view of adult: 90- Dryops arizonensisj
91- Pelonomus obscurus.
95 (4) Second segment of antenna not enlarged; antennae
pubescent, as are head and body; bases of antennae
very close together; both third and fourth segments
of maxillary palp very elongate; without tomentum;
reddish to dark brown; 4.8-6.5 mm long, 2-2.5 mm
wide (Fig. 91): Pelonomus obsourus
First, and, even more, second segment of antenna
enlarged and heavily sclerotized, forming a shield
beneath which remaining segments may be retracted and
protected; bases of antennae widely separated; parts
of body and legs with tomentum (Fig. 92) .... Heliahus....
[This section of the key is largely based upon
Musgrave (1935).] 96
96 (95) Pubescence of last abdominal sternite different from
that of preceding sternites, the last sternite often
appearing bare 99
All abdominal sternites similarly and densely
pubescent (tomentose) 97
<
97 (96) Male genitalia (Figs 93, 94) flattened dorsoventrally; in
lateral aspect paramere not enlarged apically; in dorsal
aspect penis acutely pointed at apex; female genitalia
(Fig. 95) relatively streamlined; black; 5.2-7.25 mm
long, 2.15-3 mm wide: Eel-iohus aonfluentus
Male genitalia not flattened; paramere enlarged at apex;
penis not acutely pointed; female genitalia with tip of
ovipositor (hemisternite) turned up more abruptly 98
46
-------
Fig. 92- Eeliohus lithoph-ilus adult, dorsal.
93 94 9g
Figs 93-98 Helichus confluentus: 93- aedeagus, dorsal aspect; 94-
aedeagus, lateral aspect, left side (from Musgrave); 95- female genitalia,
lateral aspect, left side. H. -immsi.: 96- aedeagus, dorsal aspect; 97-
aedeagus, left lateral aspect; 98- female genitalia, left lateral aspect
(all from Hinton).
98 (97) Paramere of male in lateral aspect with apex abruptly
enlarged (Figs 96, 97); ovipositor of female shorter
and broader (Fig. 98); black; 5.9-8 mm long, 2.4-3.3
mm wide: ' Heliohus immsi
Paramere in lateral aspect with apex gradually en-
larged, aedeagus less robust (Figs 99, 100);
ovipositor longer, narrower, and with a more
digitate ventral process (Figs 101, 102); black;
about 6-8 mm long, 2.5-3.2 mm wide: Helichus produotus
47
-------
99 (96) Uniformly covered with fine, silky pubescence; male
genitalia very elongate and slender (Figs 103, 104);
brown to black; 4.4-5.8 mm long, 2-2.5 mm wide:
Eeliohus l-ithoph-ilus
Not uniformly covered with fine, silky pubescence 100
100
102
103
104
Figs 99-104 Heliohus productus: 99- aedeagus, dorsal aspect;
100- aedeagus, right lateral aspect; 101- female genitalia, left
lateral aspect; 102- female genitalia, dorsal aspect (all from
Hinton). Aedeagus of H. lithophilus: 103- dorsal aspect;
104- left lateral aspect (all from Musgrave).
100 (99)
101 (100)
Thorax abruptly depressed behind middle; a space in
front of the scutellum glabrous or almost glabrous..
Thorax gradually depressed; without glabrous space in
front of scutellum
101
102
Glabrous space of thorax shining; first stria of
elytra almost impunctate, or at most with small
punctures not reaching base; male genitalia long
and narrow, acutely tipped (Figs 105, 106); brown
to black; 4.3-5.5 mm long, 2-2.5 mm wide: Eeliohus basalis
Glabrous space of thorax alutaceous; punctures of
first stria larger and often reaching to base of
elytron; male with a tooth-like process on antero-
medial surface of hind coxa; male genitalia with
stouter basal piece, parameres blunt-tipped (Figs
107, 108); brown to black, with bronzed pubescence;
about 4.5-5.5 mm long; 2.2-2.5 mm wide:
Hel'ichus fast-igiatus
48
-------
102 (100) Thorax with fovea on each side behind middle; para-
meres of male neither decurved nor recurved near
apex (Figs 109, 110); brown to black; 4.5-6.3 mm
long, 2-3 mm wide Heliohus striatus 103
Thorax without foveae 104
105
109
12
108
Figs 105-114 Aedeagus of Eetichus species: 105- H. basalis^ dorsal
aspect; 106- H. basalis^ left lateral aspect; 107- H. fastigiatusj
dorsal aspect; 108- H. fastigiatus^ left lateral aspect; 109- H.
striatus,, dorsal aspect; 110- H. striatus, left lateral aspect;
111- H. triangularisj dorsal aspect; 112- H. triangularis3 left
lateral aspect; 113- H. suturalis, dorsal aspect; 114- H. suturalis^
left lateral aspect (all from Musgrave).
103 (102) Elytron with alternate intervals more convex or
raised: Helichus striatus striatus
Elytron with intervals uniformly convex:
Helichus striatus foveatus
104 (102) Elytron uniformly and granularly pubescent; para-
meres of male slightly recurved (turned upward) near
apex and not acutely pointed at tips; basal piece
conspicuously curved (Figs 111, 112); gray or brown
to black; 5-6.1 mm long, 2.25-2.6 mm wide:
Heliohus triangularis
Elytron with sutural interval less pubescent; para-
meres more elongate, decurved toward apex, acutely
pointed as seen in dorsal aspect; basal piece not
conspicuously curved (Figs 113, 114); reddish brown
to black, quite variable in size and general aspect,
about 3.6-5.3 mm long, 1.7-2.3 mm wide (much smaller
than listed here in parts of Mexico and central
America): Heliohus suturalis
49
-------
105 (3) Pronotal hypomeron with a transverse or oblique ridge;
body plump and convex; near streams... LIMNICHINAE ... 106
Hypomeron without a ridge; body more elongate; on
ocean mudflats or beaches (Fig. 115) ... CEPHALOBYRRHINAE
Throsoinus (species not
included in key since they seem unrelated to water quality)
106 (105) Antennae distinctly clubbed; pronotum with smooth
anterolateral cavities for reception of antennae;
ovoid and compact; shiny reddish to black; 0.8-1 mm
long, 0.65-7 mm wide: Physemus minutus
Antennae not clubbed; pronotum without cavities for
reception of antennae; usually well over 1 mm long .,. 107
Figs 115-116 Dorsal view of adult: 115- Throsc-inus sahwartsi;
116- Limnichus sp.
107 (106) Small (1.2-2.3 mm long); antenna slender, with 10
segments; first abdominal stemite with grooves for
reception of folded hind legs (Fig. 116) : L-irm-ichus
(Although 28 species have been described from the United
States, none are known to be aquatic either as larvae or
adults, so no attempt is made here to provide a key to
them.)
Larger (2.5-4.2 mm long); antenna with 11 segments,
the first two enlarged and the remaining nine sub-
pectinate; first abdominal sternite without grooves
for the reception of folded legs (Fig. 117).Lutrochus..108
108 (107) Apical segment of maxillary palp subequal in width to
apical segment of labial palp; densely pubescent with a
yellowish cast, but dark brown where cuticle is exposed;
3-4.2 mm long, 1.75-2.3 mm wide: Lutrochus arizonicus
Apical segment of maxillary palp not over three
quarters as wide as that of labial palp 109
50
-------
109 (108)
110 (5)
111 (HO)
112 (111)
Margin of clypeus emarginate; pubescence of dorsum
thinner; eastern; 2.8-3.8 mm long, 1.5-2.1 mm wide:
Lutroahus latiaeps
Margin of clypeus straight; dorsal pubescence dense
and yellowish; southwestern; 2.5-3.5 mm long, 1.5-
2.1 mm wide (Fig. 117): Lutroehus luteus
Figs 117-118 Dorsal view of adult: 117- Lutrochus
luteusj* 118- Aaneus quadrimaouta'tus male.
Posterior margin of pronotum crenulate or finely
beaded; males with at least the anterior claw on
each foot forked at apex (this requires high
magnification and the proper angle to observe);
adults not aquatic EUBRIINAE
Posterior margin of pronotum smooth
Ill
114
Prosternum narrow, depressed between coxae; antenna
with third joint at least as long as either the
first two or next three combined; male with
flabellate antennae (Fig. 118); female larger than
male and with serrate antennae; tarsal claws of
female not toothed at base Aoneus
Prosternum of moderate width, not depressed between
coxae; tarsal claws of both sexes with a basal
tooth; antenna of male not flabellate
112
113
Elytron pale, with 7 blackish spots; mesosternal
process widely concave; male 3.5 mm long:
Aoneus ovegonensi-s
Elytron dark brown or black with 2 pale spots which
do not reach the elytral suture; these spots may be
joined by a pale marginal loop; sutural interval may
be lighter; 3.5-4.5 mm long, 2.1-2.8 mm wide (Fig.
118) : Aoneus quadr-imaeulatus
51
-------
Figs 119-120 Dorsal view: 119- Ectopr>ia nervosa
female; 120- Diaranopselaphus sp. male.
113 (111) Tarsi slender, fourth joint smaller than third and
not prolonged beneath fifth; form, color, and
pattern variable, but females larger than males and
with antenna filiform to feebly serrate whereas
antenna of male is serrate to subpectinate; brown
to black, often with yellow or orange on much of
pronotum; 3-5 mm long, about 2-3 mm wide (Fig. 119) :
Eatopria nervosa
Tarsi slightly dilated, second, third, and fourth
joints feebly emarginate, the fourth slightly pro-
longed beneath the fifth; antenna of male serrate to
feebly pectinate; brownish, thorax darker, elytra cloud-
ed and with pale, anastomosing lines; male about 3 mm
long (Fig. 120) : D-icranopselaphus variegatus
114 (110) Head usually hidden beneath broadly expanded
pronotum; base of claws with a membranous appen-
dage nearly reaching to tip of claw; antenna of
male pectinate (Fig. 121), that of female serrate;
testaceous to black; 3-4.5 mm long, 2-2.5 mm wide:
Eubvianax edwardsi
Head visible from above; base of claws without mem-
branous appendage; antenna of female moniliform,
that of male subserrate to serrate; brown to black
(Fig. 122) Psephenus 115
115 (114) Anterior margin of head distinctly bisinuate
(medially emarginate); ventral sclerite of penis
almost as wide as long, emarginate at base (Fig.
123); about 4-5.5 mm long, 1.7-3.2 mm wide (Fig. 122):
Psephenus texanus
Anterior margin of head usually arcuate; ventral
sclerite of penis at least twice as long as wide 116
52
-------
116 (115)
117 (116)
122
Figs 121-122 Dorsal view of male: 121- Eubrianax
edwcccdsi; 122- Psephenus texanus.
Maxillary palp about half as long as antenna; ventral
sclerite of penis emarginate at base (Fig. 124);
about 4-5.3 mm long, 1.7-3.1 mm wide: Psephenus
Maxillary palp about two-thirds to three-fourths as
long as antenna; ventral sclerite of penis arcuate
at base
117
Coloration uniformly dark; maxillary palp about two-
thirds as long as antenna; tarsal claws toothed at
base; aedeagus with ventral sclerite of penis slender,
parameres subparallel in dorsal aspect (Figs 125,
126); about 3.5-5 mm long, 1.6-3 mm wide:
Psephenus haldemani
Head and pronotum black, elytra brown, epipleura,
bases of legs and other parts testaceous; maxillary
palp about three-quarters as long as antenna; tarsal
claws not appreciably toothed at base; aedeagus with
ventral sclerite of penis relatively broad, parameres
with lateral margins tapering distally from near
middle (Figs 127, 128); male about 3.2 mm long, 1.6
mm wide: Psephenus murvoshi
128
125
Figs 123-128 Aedeagus of Psephenus species: 123- P. texanus, ventral
aspect with sclerite stippled; 124- P. herrieki, ventral aspect with
sclerite stippled; 125- P. haldemani, ventral aspect with sclerite
stippled; 126- P. haldeman-i, dorsal aspect; 127- P. murvoshi, ventral
aspect with sclerite stippled; 128- P. murvoshi, dorsal aspect.
53
-------
118 (5) Mandibles prominent, acutely margined above (margin
may be obscured by pubescence), rectangularly flexed
at tip; head not retracted, moderately deflexed;
pronotum acutely margined; black with cinerous
pubescence; 14-22 mm long (Fig. 131):
Stenoaolus sautellaris
Mandibles not prominent, arcuate at tip, not acutely
margined above; head strongly deflexed 119
119 (118) Antennae serrate in female, pectinate in male; middle
coxae twice as widely separated as anterior coxae;
margin of pronotum obtusely rounded; prosternum short
in front of coxae; black; 10 mm long (Fig. 129):
Anohyote-is veluti-na
Antennae slender; middle coxae no more widely
separated than anterior coxae; pronotum obtusely
margined; prosternum moderately long before coxae;
elongate oval; black; 5-6 mm long (rare) (Fig. 130):
Anchytarsus bicolor
Figs 129-131 Dorsal view of adult: 129- Anohyeteis velutina male, plus
antenna of female (from Horn); 130- Anohytca>sus substriatus female
(from Champion); 131- Stenooolus scutellaris (from Horn).
54
-------
SECTION IV
KEY TO GENERA OF AQUATIC AND SEMI-AQUATIC DRYOPOID BEETLE LARVAE
OF THE UNITED STATES
Broadly ovoid in shape and very much flattened; lateral
margins of each segment greatly expanded, the head com-
pletely concealed from a dorsal view by the expanded
anterior pronotal margin (water pennies)... PSEPHENIDAE ... 33
Less broad and flat, usually slender with a round or
triangular cross section; head exposed from dorsal view .... 2
(1) Ninth abdominal segment with a movable ventral operculum
closing a caudal chamber (Fig. 13) 3
Ninth abdominal segment without an operculum..PTILODACTYLIDAE.. 7
(2) Body cylindrical, with abdominal sternites and pleurites
greatly reduced, the tergites almost forming complete
rings on first 5 segments and forming complete ones on
segments 6-9; without retractile gills; abdominal spir-
acles lateral on segments 1-7 and dorsal on segment 8
(Unlikely to be found in our streams.) DRYOPIDAE 5
Body usually not cylindrical; abdominal sternites not
greatly reduced on anterior segments; with retractile
filamentous caudal gills emerging from caudal chamber 4
(3) Operculum with a pair of internally attached hooks (Fig. 13)... 9
Operculum without hooks, but with a flat, movable, dorsal
sclerite attached to each lateral margin; thoracic seg-
ments and first 8 abdominal segments each with a
dorsolateral flattened projection bearing many hairy
filaments (Fig. 132): CHELONARIIDAE: Chelonariwn
Figs 132-133 Left lateral aspect of larva: 132- Chelonariwn sp,
(from Boving $ Craighead); 133- Dryops sp. (from Bertrand).
55
-------
5 (3)
6 (5)
7 (2)
Operculum with 2 toothlike tubercles on posterior margin;
sides of tergites transversely grooved; ninth abdominal
segment flattened dorsally and emarginate at apex: Helichus
Operculum without tubercles; tergites not transversely
grooved; ninth abdominal segment convex dorsally 6
Tergites with anterior margins smooth; gular sutures
present (Fig. 133):
Tergites (except pronotum) with numerous longitudinal
carinae arising near each anterior margin; gular
sutures obliterated, with 2 pairs of setae near where
Dryops
sutures would be:
Pelonomus
Abdominal segments 1-7 each with 2 ventral tufts of
filamentous gills; submentum not divided; ninth
abdominal segment without prehensile appendages
bearing hooks (Fig. 135) : Stenocolus
Abdominal segments 1-7 without gill tufts; submentum
divided longitudinally into 3 parts; anal region of
ninth abdominal segment with 2 curved prehensile
appendages covered with short spines 8
134
100
Figs 134-135 Larva: 134- Anahytarsus bicolor, left lateral
aspect (from Bertrand); 135- Stenoaolus scutellca'isl3 ventral
aspect (from Boving § Craighead).
8 (7) Ninth abdominal segment with numerous fingerlike anal gills;
apex without projection (Fig. 134) Anchytarsus
Ninth abdominal segment with 3 median anal gills and 1
gill lateral to each prehensile appendage; dorsal,
flattened apex of ninth segment with small raised
projection: Anohycteis
56
-------
(4) Abdomen with pleurites on at least the first 6 segments;
ventral surface of thorax sclerotized, usually with
sternites; thoracic pleurites often divided into 2
or 3 parts; apex of ninth abdominal segment typically
emarginate ELMIDAE 10
Abdomen with pleurites present on only first 4 segments;
with erect hairs along medial margin of each narrow,
undivided thoracic pleurite; thoracic sternites
membranous or absent; apex of ninth abdominal segment
evenly rounded; each eyespot with 5 ocelli and with
another ventral ocellus below base of antenna; body
robust; head almost as wide as thorax, but usually re-
tracted within it (Figs 136, 137, 138):
LIMNICHIDAE: Lutroehus
(Larvae of the other genera are unknown; they are probably
not aquatic.)
Figs 136-138 Larva of Lutrodhus luteus: 136- dorsal
aspect; 137- ventral aspect; 138- lateral aspect.
3 (9) Abdomen with pleura on first 8 segments 11
Abdomen with pleura on first 6 or 7 segments...ELMINI 16
I (10) Body rather broad, lateral margins expanded*...LARINI 12
Body slender, elongate, cylindrical or hemicylindrical
ELMINI, in part 13
2 (11) With coarse, prominent spines along lateral margins;
dorsal surface ridged on each side; last segment rather
square-sided and flat dorsally; procoxal cavities
open behind; up to 16 mm long (Figs 139, 140): Lara
Without marginal spines; body quite flattened and with
rather smooth surface; testaceous to brown, somewhat
translucent; procoxal cavities closed behind (Figs
141, 142): Phanoeerus
57
-------
139
140
Figs 139-142 Larva of Lara avara: 139- dorsal aspect;
140- ventral aspect. Larva of FhanooeTus olavioornis:
141- dorsal aspect; 142- ventral aspect.
13 (11) Last abdominal segment very long and slender (at least
4 times as long as wide); operculum confined to poster-
ior third of segment (Figs 143, 144): Dubiraphia
Last abdominal segment not conspicuously long or
slender (less than 4 times as long as wide); operculum
not confined to apical third 14
14 (13) Head tuberculate, with suberect spines; anterior margin
of head without a prominent frontal tooth on each side;
body subcylindrical, yellowish; often more than 8 mm long
(Figs 145, 146): Narpus
Head without suberect spines, anterior margin with a
prominent frontal tooth on each side (Fig. 13) 15
15 (14) Body cylindrical; pleural sutures extend to basal half
of ninth abdominal segment; procoxal cavities closed
behind (Fig. 147); larger- often longer than 6.5 mm
(Fig. 148): Cylloepus
Body hemicylindrical; pleural sutures not extending
onto ninth abdominal segment; procoxal cavities open
behind; smaller, less than 6.5 mm (Figs 149, 150):Khizelmis
16 (10) Prothorax with a posterior sternum (Fig. 13), so
procoxal cavities are closed behind 17
Prothorax without posterior sternum; procoxal cavities
open behind 25
58
-------
143 144 145 |46
Figs 143-146 Larva of Dubiraphia sp.: 143- dorsal aspect;
144- ventral aspect. Larva of Narpus aonaolor: 145- dorsal
aspect; 146- ventral aspect.
148
149
150
Figs 147-150 Larva: 147- Cylloepus sp., ventral aspect of
thoracic and first abdominal segment (from Hinton);
148- C. montanus, dorsal aspect (from Bertrand). Larva of
Ekizelmis nigra'. 149- dorsal aspect; 150- ventral aspect.
17 (16) Posterolateral margins of abdominal segments 1-8
produced into spine-like processes; body rather
robust (Figs 151, 152): Anayronyx
Margins of abdominal segments not thus produced;
body elongate 18
59
-------
18 (17) Dorsum of all but last segment bearing spatulate tuber-
cles or short spines arranged in about 10 conspicuous
longitudinal or diagonal rows; last segment with a
mid-dorsal longitudinal ridge and lateral margins
bearing spatulate tubercles (Figs 153, 154, 155) : Re-terelmis
Dorsum without such spiny tubercles, although there
may be rows of small, flat tubercles 19
Figs 151-155 Larva of Ancyronyx vcwiegata: 151- dorsal aspect;
152- ventral aspect. Larva of Heterelmis vulnerata: 153- dorsal
aspect; 154- lateral aspect; 155- ventral aspect.
19 (18)
20 (19)
21 (20)
Anterior margin of head on each side with a distinct
frontal tooth (Fig. 13)
Anterior margin of head without distinct frontal tooth
22
20
Dorsum with relatively conspicuous, flattened tubercles
often arranged in longitudinal rows; abdominal tergites
often with mid-dorsal pale spots; last segment with a
weak mid-dorsal longitudinal ridge 21
Tubercles of dorsum inconspicuous, not arranged in longitu-
dinal rows; without mid-dorsal pale spots; last segment
convex dorsally-. without median ridge (Figs 159, 160) :
Neoelvris
Last abdominal segment conspicuously long and slender (3
times longer than wide); mid-dorsal spots widest near
middle of each segment; dorsal tubercles not arranged in
parallel longitudinal rows: Hexaoylloepus
Last segment not unusually long or slender; mid-dorsal spots
widest near posterior of segments; dorsal tubercles
partially arranged in parallel longitudinal rows (Figs
156-158): Microcylloepus
60
-------
156
Figs 156-160 Larva of Microcylloepus
157- ventral aspect; 158- lateral aspect
159- dorsal aspect; 160- ventral aspect.
160
'. 156- dorsal aspect;
Larva of Neoelmis sp.:
22 (19) Tergite of last abdominal segment with prominent median
and sublateral longitudinal carinate ridges (in cross
section, the segment would be pentagonal) (Figs 161,
162) : Neocylloepus
Dor sum of last abdominal segment not carinate or prom-
inently ridged ......................................... 23
161
163
164
Figs 161-164 Larva of Neooylloepus boesel-i: 161- dorsal aspect;
162- ventral aspect. Larva of Ordobrevia nubifera: 163- dorsal
aspect; 164- ventral aspect.
61
-------
23 (22) Second segment of antenna more than twice as long as
first; prosternum with anterior suture obliterated;
no suture extending from procoxal cavity to lateral
margin of pronotum (Figs 163, 164): Ordobrewia
Second segment of antenna less than twice as long as first;
prosternum with anterior median suture; suture from pro-
coxal cavity to lateral margin may or may not be visible.24
24 (23) Suture from procoxal cavity to lateral margin distinct;
large and rather flattened, commonly well over 1 mm
wide; our species usually relatively smooth, black,
and rather shiny (Figs 165, 166): Elsianus
Suture from procoxal cavity to lateral margin indistinct
or absent; body more convex and elongate, smaller, not
more than about 1 mm wide; cuticle more granular in ap-
pearance, from pale tan to dark brown, not shiny (Figs
167, 168): Stenelmis
Figs 165-168 Larva of Elsianus texanus: 165- dorsal aspect;
166- ventral aspect. Larva of Stenelmis sp.: 167- dorsal aspect;
168- ventral aspect.
25 (16) Postpleurite composed of 1 part (Fig. 13) 26
Postpleurite composed of 2 parts (Fig. 177) 27
26 (25) Body robust, broad, subtriangular in cross section; with
spatulate spines along lateral margins and mid-dorsal
line (Figs 169, 170): Ampumixis
Body long and slender, hemicylindrical; without prominent
clusters of spines (Figs 171, 172): Cleptelmis
27 (25) Mesopleuron composed of 1 part (Fig. 177) 28
Mesopleuron composed of 2 parts (Fig. 179) 29
62
-------
"li I f C.
Figs 169-172 Larva of Ampwnixis d-ispar : 169- dorsal aspect;
170- ventral aspect. Larva of Cleptelmis sp.: 171- dorsal
aspect; 172- ventral aspect.
Figs 173-177 Larva of Promoresia tardella: 173- dorsal aspect;
174- ventral aspect; 175- lateral aspect. Larva of Optioservus
sp.: 176- dorsal aspect; 177- ventral aspect.
28 (27)
Dorsum of each segment with median and sub-lateral
humps (Figs 173, 174, 175):
(last segment strongly humped in P. elegans ,
feebly humped in P. tardella}
Dorsum without such humps (Figs 176, 177):
PromoTesi-a
Optioservus
29 (27)
Abdominal segments 1-6 with pleura; last segment with
2 long, acute, narrowly separated apical processes
(Figs 178, 179): MaaTonyehus
Abdominal segments 1-7 with pleura 30
63
-------
30 [29) Body long, slender, and hemicylindrical; apex of last
segment rather deeply emarginate, the angles produced
and acute (Figs 180, 181) Zaitzevia
Body usually less elongate, subtriangular in cross section;
apex of last segment shallowly emarginate, angles less
acute 31
Figs 178-181 Larva of Macronyehus gldbratus : 178- dorsal aspect;
179- ventral aspect. Larva of Zaitzevia parvula: 180- dorsal
aspect; 181- ventral aspect.
31 (30) Abdominal segments with mid-dorsal humps which are es-
pecially prominent toward the rear, each hump bearing
conspicuous scale-like hairs (Fig. 184); dorsum of
each thoracic segment with 2 longitudinal dark spots
on each side (Figs 182-184): Gonielmis
Abdominal segments without mid-dorsal humps; thorax with-
out dark markings 32
32 (31) Western; tubercles of dorsum relatively dense, separated
by less than their own widths, crowded along posterior
margins of segments; mesothorax with anterior portion
of pleuron much smaller than posterior portion; mature
larva 4-5 mm long (Figs 185, 186): Heterlirmius
Eastern; tubercles of dorsum sparse, separated by more
than their own widths except along mid-dorsal line,
marginal tubercles separated by their own widths;
mesothorax with anterior portion of pleuron subequal
to posterior portion; mature larva not over 3 mm
long (Figs 187, 188): Oulirmius
64
-------
182
184
Figs 182-184 Larva of Gonielmls dietriahi: 182- dorsal
aspect; 183- ventral aspect; 184- lateral aspect.
Figs 185-188 Larva of Heterlirm-ius oovpulentus: 185- dorsal
aspect; 186- ventral aspect. Larva of Oulimnius latiusoulus:
187- dorsal aspect; 188- ventral aspect.
33 (1) Ninth abdominal segment with a ventral operculum
closing a caudal chamber containing 3 tufts of re-
tractile filamentous gills; without gills on other
parts of abdomen; expanded lateral portions of
abdominal segments separated EUBRIINAE 34
Ninth abdominal segment without ventral operculum; with
pairs of ventral tufts of filamentous gills on 4 or 5
abdominal segments; expanded lateral portions of ab-
dominal segments fitting tightly together at margin 36
65
-------
Figs 189-190 Larva of Aoneus quadrimaoulatus: 189- dorsal
aspect; 190- ventral aspect.
193
Figs 191-194 Larva of DicTanopselaphus sp.: 191- dorsal aspect;
192- ventral aspect. Larva of Eetopri-a nervosa: 193- dorsal aspect;
194- ventral aspect.
195
Figs 195-198 Larva of Eubrianax edwardsi: 195- dorsal aspect;
196- ventral aspect. Larva of Psephenus texanus: 197- dorsal aspect;
198- ventral aspect.
66
-------
34 (33) Apex of ninth abdominal segment narrowly emarginate
(i.e., with a distinct notch) (Figs 189, 190): Acneus
Apex of ninth segment truncate or broadly arcuate 35
35 (34) Ninth abdominal segment not rectangular, the sides
expanding from base toward broadly arcuate apex;
lateral expansions of eighth segment short, not
forming part of lateral margin of body outline
(Figs 191, 192): Viavanopselaplms
Ninth abdominal segment almost rectangular; lateral
expansions of eighth segment forming part of margin
of body outline (Figs 193, 194): Ectopria
36 (33) Eighth abdominal segment with lateral expansions;
abdomen with 4 pairs of gills (Figs 195, 196): Eubvianax
Eighth abdominal segment without lateral expansions;
abdomen with 5 pairs of gills (Figs 197, 198): Psephenus
67
-------
SECTION V
REFERENCES
* Useful references not cited in the text.
Arnett, R. H., Jr. 1963. "The beetles of the United States." Catholic
University of America Press, Washington, D. C. xi, 1112 pp.
*Blackwelder, R. E. 1939. "Fourth supplement 1933 to 1938 (inclusive) to
the Leng catalogue of Coleoptera of America, north of Mexico."
Mount Vernon, N. Y. 146 pp.
* 1944. Checklist of the coleopterous insects of Mexico, Central
America, the West Indies, and South America. Part 2. United States
National Museum Bulletin No. 185:189-341.
* 1957. Checklist of the coleopterous insects of Mexico, Central
America, the West Indies, and South America. Part 6. United States
National Museum Bulletin No. 185:vii, 927-1492. (Extensive
bibliography)
Brown, H. P. 1970a. Neooyllaepus, a new genus from Texas and Central
America (Coleoptera:Dryopoidea:Elmidae). Coleopterists ' Bulletin,
24(1):l-28.
1970b. A new species of Psephenus from Arizona (Coleoptera,
Psephenidae). Coleopterists' Bulletin, 24(2):34-38.
1970c. A key to the dryopid genera of the New World (Coleoptera,
Dryopoidea). Entomological News, 81:171-175.
1971. A new species of Elsianus from Texas and Mexico, with records
of other species in the United States (Coleoptera:Dryopoidea:Elmidae)
Coleopterists ' Bulletin, 25(2):55-58.
and Chad M. Murvosh. 1970. Lutrochus arizonicus new species, with
notes on ecology and behavior (Coleoptera, Dryopoidea, Limnichidae).
Annals of the Entomological Society of America, 63(4):1030-1035.
*Burke, H. B. 1963. Notes on Texas riffle beetles (Coleoptera, Elmidae).
The Southwestern Naturalist, 8(2):111-114.
*Casey, T. L. 1889. Coleopterological notices. I. Annals of the New York
Academy of Sciences, 5:39-198. (Limnichidae)
1893. Coleopterological notices. V. Annals of the New Ibrk Academy
of Sciences, 7:281-606. (Psephenidae, Limnichidae, Elmidae)
1912. Descriptive catalogue of the American Byrrhidae. Memoirs on
Coleoptera, 3:1-69. (Limnichinae)
Chandler, H. P. 1954. New genera and species of Elmidae from California.
Pan-Pacific Entomologist, 30:125-131. (AtracteImis, Rhizelmis}
Collier, J. E. 1969. "A Taxonomic Revision of the Genus Optioservus
(Coleoptera:Elmidae) in the Nearctic Region." Ph. D. Thesis,
University of Minnesota. University Microfilms-, Inc., Ann Arbor,
Michigan.
Crowson, R. A. 1967- "The natural classification of the families of
Coleoptera." Reprinted by E. W. Classey Ltd., Hampton, Middlesex,
England, with addenda and corrigenda. 214 pp.
Darlington, P. J., Jr. 1929. On the dryopid beetle genus Lara. Psyche,
36(4):328-331.
69
-------
*Hatch, M. H. 1965. "The Beetles of the Pacific Northwest. Part IV."
University of Washington Press, Seattle. 268 pp.
*Hilsenhoff, W. L. 1971. Changes in the downstream insect and amphipod
fauna caused by an impoundment with a hypolimnion drain. Annals of
the Entomological Society of America, 64(3):743-746.
Hinton, H. E. 1937- Eelichus immsi, sp. n. , and notes on other North
American species of the genus (Coleoptera, Dryopidae). Annals of
the Entomological Society of America, 30(2):317-322.
* 1939. An inquiry into the natural classification of the Dryopoidea,
b~ased partly on a study of their internal anatomy. Transactions of
the Royal Entomological Society of London, 89:133-184.
1940. A monographic revision of the Mexican water beetles of the
*
family Elmidae. Novitates zoologiae, 42:217-396.
Horn, G. H. 1870. Synopsis of the Parnidae of the United States. Trans-
actions of the American Entomological Society, 3:29-42.
1880. Synopsis of the Dascillidae of the United States. Transac-
tions of the American Entomological Society, 8:76-114.
"Kirk, V. M. 1969. A. List of Beetles of South Carolina. Part 1 - North-
ern Coastal Plain. South Carolina Agricultural Experiment Station,
Clemson, S.C., Technical Bulletin 1033, 124 pp.
" 1970. A List of the Beetles of South Carolina. Part 2 - Mountain,
Piedmont, and Southern Coastal Plain. South Carolina Agricultural
Experiment Station, Clemson, S.C., Technical 'Bulletin 1038, 117 pp.
La. Rivers, Ira. 1950. The Dryopoidea known or expected to occur in the
Nevada area (Coleoptera). Wasmann Journal of Biology, 8(1):97-111.
LeConte, J. L. 1852. Synopsis of the Parnidae of the United States.
Proceedings of the Academy of Natural Sciences of Philadelphia,
6:41-45.
1874. Descriptions of new Coleoptera chiefly from the Pacific
slope of North America. Transactions of the American Entomological
Society, 5:43-72.
* and G. H. Horn. 1883. Classification of the Coleoptera of North
America. Smithsonian Miscellaneous Collections, 26(4), No. 507,
i-xxxvii,1-567.
Leech, H. B. and H. P. Chandler. 1956. Aquatic Coleoptera, Chapter 13
in Usinger, R. L. (ed.), "Aquatic Insects of California." University
of California Press, Berkeley; i-ix, 508 pp.
Leech, H. B. and M. W. Sanderson. 1959. Coleoptera. Chapter 38 in
Edmondson, W. T. (ed.), "Freshwater Biology." 2nd ed., Wiley, New
York, i-xx, 1248 pp.
*Leng, C. W. 1920. "Catalogue on the Coleoptera of America, north of
Mexico." Mount Vernon, N. Y. 470 pp.
1933. Second and third supplements 1925 to 1932 (inclusive) to:
"Catalogue of the Coleoptera of America, north of Mexico." Mount
Vernon, N. Y, 112 pp.
Loding, H. P. 1945, "Catalogue of the Beetles of Alabama." Monograph
11, Geological Survey of Alabama, 172 pp.
Musgrave, P. N. 1935. A synopsis 6f the genus Heliohus Erichson in the
United States and Canada, with descriptions of new species
(Coleoptera: Dryopidae). Proceedings of the Entomological Society of
Washington, 37(7):137-145.
70
*
-------
*Pacheco, F. 1964. Sistematica, Filogenia y Distribucion de los '
Heteroceridos de America (ColeopterarHeteroceridae) . Monografias del
Colegio de Post-graduados Esauela Nacional de Agricultura3 Chapingo,
Mexico. 115 pp.
Sanderson, M. W. 1938. A monographic revision of the North American
species of Stenelmis (Dryopidae:Coleoptera). University of Kansas
Science Bulletin3 25(22):635-717.
1953-54. A revision of the Nearctic genera of Elmidae (Coleoptera).
Journal of the Kansas Entomological Society 3 26(4):148-163; 27(1):
1-13.
Sharp, D. 1882. Insecta, Coleoptera, Haliplidae, Dytiscidae, Gyrinidae,
Hydrophilidae, Heteroceridae, Parnidae, Georissidae, Cyathoceridae.
Biologia centrali-americana3 1(2):1-144.
* 1902. Insecta, Coleoptera, Cryptophagidae, Lathridiidae, Myceto-
phagidae, Dermestidae, Byrrhidae. "Biologia centrali-americana,
2(1):625-688.
*Sinclair, R. M. 1964. "Water quality requirements of the Family Elmidae
(Coleoptera), with keys to the larvae and adults of the eastern
genera." Tennessee Stream Pollution Control Board, Tennessee
Department of Public Health,Nashville, Tennessee. 14 pp.
Thorpe, W. H. 1950. Plastron respiration in aquatic insects. Biological
Reviews (Cambridge)*25:344-390.
and D. J. Crisp. 1949. Studies on plastron respiration. IV-
Plastron respiration in the Coleoptera. Journal of Experimental
Biology^ 26(3):219-260.
*Young, F. N. 1954. The Water Beetles of Florida. University of Florida
Studies. Biological Science Series^ 5(l):l-238.
71
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SECTION VI
GLOSSARY
accessory stria -- a short stria which usually fuses with another stria
near the base of the elytron (Figs 25, 63).
aedeagus -- male genitalia (Fig. 10).
alutaceous -- covered with minute cracks or wrinkles, like the human
skin.
angle -- corner (e.g., apical angle of pronotum of humeral angle or
elytron as in Fig. 1).
apex (adj., apical} -- that part of a joint or segment farthest from the
base by which it is attached; the apex of the thorax is anterior, that
of the abdomen posterior.
arcuate -- arched, bow-like, rounded.
basal piece -- that part of the aedeagus to which the penis and parameres
are attached (Fig. 10).
base (adj., basal} -- that part of a joint nearest to the main body;
the base of the thorax is the posterior or hind portion, that of the
abdomen being the anterior or front portion.
bimaculate -- bearing two spots (maculae).
carina -- an elevated ridge or keel (Figs 1, 4).
carinate -- exhibiting one or more carinae.
cinereous -- ashy gray in color.
clypeus -- that part of the head below the frons to which the labrum is
attached (Figs 2,3).
coxa -- the basal segment or joint of the leg (Fig. 2).
crenate -- scalloped with small, blunt, rounded teeth (Fig. 1).
crenulate -- with small, evenly rounded scallops.
decumbent -- bending downward (as decumbent hairs in contrast with erect
ones).
decurved -- bowed or curved downward.
disc or disk -- the central upper surface (Fig. 1).
73
-------
dor sum -- the dorsal or upper surface; opposite of venter.
elytra (plural of elytron*) -- the leathery or sclerotized anterior wings
which, at rest, cover the hind or flight wings, meeting in a straight
line down the middle of the dorsum.
elytral interval -- the region between two adjacent elytral striae; the
intervals are counted from the center,the first being the sutural interval
(Fig.l) or that between the midline and the first stria.
elytral suture -- the mid-dorsal line where the elytra meet in repose.
emarginate -- notched, indented, hollowed out, curved inward.
epipleuron -- the deflexed or bent-under portion of the elytron just be-
low the edge (Figs 2-4) .
exserted coxa -- a protruding coxa; one that juts outward.
femur (plural, femora] -- that segment of the leg between the trochanter
and the tibia (Fig. 2), sometimes the only part of the leg visible from
above.
filiform -- thread-like; slender and of equal diameter; the joints of a
filiform antenna are relatively uniform and shaped like elongate beads.
flabellate -- fan-shaped (Fig. 118).
fovea -- a pit or deep depression.
fuscous -- dark brown; reddish black.
genitalia -- the genital organs collectively (Figs 10, 11) .
glabrous -- smooth and bare.
gular suture -- line of division between the gula (Fig. 7) and the gena
lateral to it.
hemisternite -- basal portion (coxite) of female genitalia (Fig. 11),
sometimes adapted for oviposition.
humerus -- the basal exterior angle of the elytron (Figs 1, 2).
hydrofuge pubescence -- tomentum; water-repellent fuzz.
hypomeron -- the deflexed or bent-under portion of the pronotum beneath
the lateral margin or edge (Figs 2, 3); elytral hypomeron = epipleuron.
•immaculate -- without spots or blotches.
74
-------
labial palp -- jointed lateral appendage of the labium (Figs 2, 7, 15).
labium -- lower lip formed from fused second maxillae (Figs 2, 7, 13, 15).
labrwn -- upper lip, attached basally to clypeus and covering bases of
mandibles (Figs 2, 3).
lamellate antenna -- one with a number of terminal segments that are
flattened and usually appressible like the pages of a book (Fig. 92).
lotto -- with moving water, either wave-washed or flowing.
maculate -- with spots (maculae).
mandible -- lateral jaw (Figs 2, 3, 5).
maxilla -- lateral mouth part between mandible and labium (Figs 6, 13,
14).
maxillary palp -- jointed appendage of maxilla (Figs 2, 3, 6, 14);
often the most conspicuous mouthpart on the intact specimen.
mesopleuron -- pleuron of mesothorax.
mesosternum -- sternum of mesothorax (Figs 2, 13).
mesothorax -- middle segment of thorax; to it are attached the second
or middle pair of legs and, in adults, the elytra.
metapleuron -- pleuron of metathorax.
metastermm -- sternum of metathorax (Figs 2, 13) .
metathorax -- third segment of thorax; to it are attached the third
or hind pair of legs and, in adults, the flight wings.
moniliform antenna -- one with joints or segments like rather uniform
globular beads.
ocellus (plural, ocelli} -- a simple eye or eyespot.
ochreous or ochraceous -- brownish yellow.
operculum -- trapdoor-like ventral cover of gill chamber on last ad-
dominal segment of larva (Fig. 13).
ovipositor -- sclerotized parts of female genitalia (usually hemistern-
ites) adapted for insertion of eggs into the substrate (e.g., in Helichus3
Figs 95, 101, 102).
paramere -- lateral lobe of male genitalia, attached to basal piece and
enclosing penis (Fig. 10).
73
-------
pectinate antenna -- one in which a number of segments are enlarged into
long tooth-like projections so that the antenna resembles a comb or a
garden rake (Fig. 121).
penis -- median lobe of male genitalia, attached to basal piece and flanked
or enclosed by the paired parameres (Fig. 10).
pile -- pubescence; fuzz; short, dense hairs.
plastron -- gaseous film maintained under water by means of small, close-
set, hydrofuge hairs covering parts of the body surface.
pleurite -- a sclerite covering part or all of a pleuron (Fig. 13) .
pleuron (plural, pleura] -- the lateral region of a body segment between
tergum and sternum.
postpleurite -- the pleurite of the prothorax behind the coxa (Fig. 13).
procoxa -- the coxa of a front leg (Fig. 3).
pronotum -- the dorsal portion of tergum of the prothorax (Figs 1, 3, 12).
propleuron -- the pleuron of the prothorax.
prosternal process -- posterior median projection of the prosternum
between the procoxae (Fig. 2).
prosternum -- sternum of the prothorax (Figs 2, 3, 13).
prothorax -- first segment of thorax, to which head is attached and into
which the head may be partially or entirely withdrawn; this segment also
bears the front pair of legs.
pubescence -- fuzz; hairs.
puncta, punctation -- small punctures or pits in the surface; rows of
such punctures form the striae of the elytra.
recurved -- bent or curved upward.
riparian -- shore-dwelling; occurring at or near the margin of the water.
rufous -- reddish.
sclerite --a hardened piece or section of the exoskeleton.
sclerotized -- hardened.
scutellum -- the wedge-shaped median dorsal sclerite between the basal
portions of the elytra (Fig. 1).
76
-------
sericeous -- silky; downy.
serrate -- saw-toothed (e.g., serrate elytral margin as in Fig. 1 or
serrate antenna as in Fig. 120).
sternite -- a sclerite of the sternum (Figs 1-4, 13).
sternum -- the ventral part of a body segment.
stria -- a row of punctures forming a longitudinal line (Fig. 1).
stylus -- sensory projection of the female genitalia attached to hemi-
sternite (Fig. 11).
sub- (prefix) -- almost; nearly; slightly; close to; just below.
(e.g., subequal; subquadrate.)
sublateral carina -- a lateral longitudinal carina parallelling the
lateral margin (Figs 1, 3).
submentum -- the basal sclerite of the labium by which the labium is
attached to the gula of the head (Fig. 7).
sulaus (plural, sulci] -- a groove or furrow.
suturat interval -- the first or median elytral interval (Fig. 1).
sutural vitta --a vitta or stripe bordering the elytral suture (Figs
81, 82).
suture -- a seam or impressed line between two contiguous sclerites;
the median line of juncture of the elytra (Figs 12, 13).
tarsus -- the foot; the distal part of the leg attached at the apex of
the tibia, consisting typically of five joints or segments and bearing
the tarsal claws (Fig. 2).
tergite -- a sclerite of the tergum (the dorsal part of a segment)
(Figs 1, 12, 13).
testaceous -- yellow; brownish yellow.
thorax -- the body region between the head and the abdomen; the thorax
bears the legs and, in adults, the wings.
tibia -- the joint or segment of the leg between the femur and the
tarsus (Fig. 2).
tomentum -- a dense patch of hairs, either prominent, as on the tibia
(Fig. 2), or closely appressed to the surface and providing a plastron
on various body sclerites.
77
-------
transverse coxa -- an elongate coxa extending transversely like the hind
coxa of Fig. 2.
travertine -- a rather porous calcareous stone which forms on the sub-
strate in falls and rapids of streams with a very high calcium content.
troohantin -- a small piece or joint on the outer side of the coxa (well
separated from the trochanter) which may be exposed or may be hidden
beneath the pronotum or prosternum.
truncate -- cut off squarely or abruptly at the tip.
tubercle -- a small button-like or pimple-like projection of the exo-
skeleton.
tuberculate -- bearing tubercles.
wribone --an embossed, elevated knob on the humeral angle of an elytron
(Fig. 1).
venter -- the ventral surface or under side of the body.
vitta -- a longitudinal stripe, usually relatively broad.
vittate -- striped; bearing vittae.
78
-------
SECTION VII
INDEX OF SCIENTIFIC NAMES
abnormis (Cylloepus)3 14,40
AoneuSj 23,51,67
oregonensis3 23,51
quadrimaoulotus3 23,51
addenda (Cleptelmis)3 14,35
ampliatus (Optioservus)3 17,45
Ampumixis3 14,62
dispox>3 14,35
Anohyoteis3 24,56
velutina3 24,54
Anohytarsus3 24,56
bicolor, 24,54
Ancyronyx3 4,14,59
variegata3 14,27
angustus (Carpus), 16,35
antennalis (Stenelmis)3 20,32
arizonensis (Dryops), 21,46
cadsonicus (Lutroahus)3 22,50
(Narpus), 17,36
Atraete1mis3 14
wauona3 14,35
avara amplipennis (Lara)3 13,26
avara (Lara)3 13,26
bosalis (Eeli-ohus)3 21,48
~be
-------
exilis (Stenelmis), 20,31
fastiditus (Optioservus), 17,45
fastigiatus (Heliohus), 22,48
ferrugineus (Hexaoy1loepus), 16,39
fuscata (Stenelmis), 20,32
gehringi (Lara), 13,26
giulianii (Dubiraphia), 15,37
glabra (Eeterelmis), 15,39
glabratus (Macronyohus), 16,27
Gonielmis, 4,15,64
dietriohi, 15,42
grossa (Stenelmis), 20,31
haldemani (Psephenus), 24,53
Eeliohus, 1,3,4,21,46,56
basalis, 21,48
confluent-us, 22,46
fastigiatus, 22,48
irransi, 22,47
lithophilus, 22,48
produotus, 22,47
striatus foveatus, 22,49
striatus, 22,49
suturalis, 22,49
tv-ianguloT'is, 22,49
herri-oki (Psephenus), 24,53
Heterelmis, 4,8,15,39,60
glabraj 15,39
obesa, 15,39
vulnerata, 15,39
Heterlirm-ius j 15,43,64
coTpulentus3 15,43
koebele-i, 16,43
Heteroceridae, 1
Hexaaylloepus, 16,60
ferrug-ineus 3 16,39
humerosa (Stenelmis), 20,32
hungerfordi (Stenelmis)- 20,32,33
immsi (Helichus), 22,47
-Lrrmunis (Optioservus)} 17,44
knobeli (Stenelmis)} 20,31
koebelei (Heterlimn-Lus)3 16,43
Lara, 2,13,26,57
avara amplipennis, 13,26
avara, 13,26
gehring-L, 13,26
Larini, 2,13,26,57
lateral-Is (Stenelmis), 20,30
latioeps (Lutrochus), 22,51
latiusoulus (Oulirm-ius), 19,41
leconte-i (Chelonarium) , 13,25
Limnichidae 1,2,22,25,57
Limnichinae, 22,50
Ltrmiahusj 2,4,22,50
Hthoph-ilus (Helichus), 22,48
luteus (Lutrochus)3 23,51
Lutroohus, 1,2,4,5,22,50,57
arisoniaus, 22,50
laticeps, 22,51
luteus, 23,51
Maoronyahus, 4,16,63
glabratus, 16,27
markel-i (Stenelmis), 21,34
mera (Stenelmis), 21,31
Miorooylloepus, 4,16,40,60
browni, 16,41
moapus, 16,41
fraxinus, 16,41
moapus, 41
pusillus, 16,40
aptus, 16,41
lodingi, 16,41
perditus, 13,16,41
pusillus, 16,41
similis, 16,41
thermarum, 16,40
minutus (Physemus), 23,50
mirabilis (Stenelmis)., 21,32
moapus (Microcylloepus), 16,41
fraxinus (Miorocylloepus), 16,41
moapus (Miorooylloepus)- 41
moestus (Elsianus), 15,38
murvoshi (Psephenus), 24,53
musgravei (Stenelmis), 21,33
Narpus, 16,35,58
angustus, 16,35
arizonious, 17,36
oonoolor, 17,36
fleooylloepus, 8,10,17,61
boeseli, 17,38,61
Neoelmis, 17,60
oaesa, 17,38
nervosa (Eatopria), 23,52
nigra (Rhizelmis), 20,34
nubifera (Ordobrevia), 19,28
obesa (Heterelmis)3 15,39
obsourus (Pelonomus), 22,46
Optioservus, 17,43,63
ampliatus, 18,45
oanus, 17,45
oryophilus, 17,44
divergens, 17,44
fastiditus, 17,45
80
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Qptioservus immunis3 17,44
ovaliSj 17,45
osarkensiSj 13,17,44
peoosensisj 18,44
quadrimaeulatus3 18,45
sandersoni3 13,18,44
seriatus3 19,45
trivittatus3 18,19,44
Ordobrevia3 19, 61,62
nubifera3 19,28
oregonensis (Aaneus)3 23,51
ornata ( Cleptelmis)3 14,35
OulirmiuSj 19,64
Iatiusoulus3 19,41
oval-is (Optioservus) , 17,45
osarkensis (Optioservus)3 13,17,44
parkeri (Cylloepus)3 14,40
parva (Stenelmis)3 21,31
parvula (Zaitzevia) , 21,28
peoosensis (Optioservus)3 8,44
Pelonomus3 3,22,56
obssuruSj 22,46
Phanoaerus3 2,4,13,57
olavioornis 3 13,26
PhysemuSj 23
m-inutus3 23,50
Polyphaga, 1
productus (Heliehus)3 22,47
Promores-ia, 19,42,63
e~legans3 19,42
tca>della3 19,42
Psephenidae. 1,2,23,26,55
Psepheninae, 24
Psephenus3 1,2,4,5,24,52,67
haldeman-i3 24,53,
hevricki, 24,53
murvoshij '24,53
texanus3 24,52
Ptilodactylidae, 1,5,24,26,55
pusillus (M-Lorooylloepus)3 16,40
aptus (M-iorooyfloepus), 16,41
loding-L (M-ioTocylloepus)3 16,41
perditus (Microoylloepus)3 13,16,41
pusillus (Mi-oTOoylloepus)3 16,41
si-milis (Miorooylloepus)3 16,41
quadrimaaulata (Stenelmis)3 21,33
quadfimaaulatus (Aoneus)3 23,51
(Optioservus)3 18,45
quadrinotata (Dubiraphia)- 15,37
Khizelmis, 20,58
nigras 20,34
sandersoni (Optioservus)3 13,18,
44
(Stenelmis)3 21,30
soutellaris (Stenoaolus)3 24,54
seriatus (OptioseTVus)3 19,45
sexlineata (Stenelmis),, 21,30
sexualis (Cylloepus)3 14
shoemdkei (Elsianus)„ 15,38
sinuata (Stenelmis)3 21,33
Stenelmis3 7,20,28,62
antennalis3 20,32
beameri3 20,30
bioarinata3 20,31
oalida calida3 20,28
moapa3 20,25
ooncinna, 20,30,
conveozula3 20,34
crenata3 20,30
deoovata3 20,33
_^ douglasensis, 20,31
exigua3 20,30
exilis3 20,31
fusoata3 20,32
grosscij 20,31
humerosa3 20,32
hungerfordi3 20,32,33
knobeli, 20,31
Iateralis3 20,30
markeli3 21,34
mera3 21,31
mirabilis3 21,32
musgraveij 21,33
parva3 21,31
quadrimaculata3 21,33
sandeTsoni, 21,30
sexlineata3 21,30
sinuata3 21,33
vittipennis, 21,33
Stenobolus3 24,56
scutellarisj 24,54
striatus foveatus (Heliohus), 22,
49
striatus (Heliehus)3 22,49
sutwcalis (Heliehus)3 22,49
tca>della (Pvomovesia)3 19,42
texanus (Elsianus)3 15,38
(Psephenus)3 24,52
thermae (Zaitzevia)3 21,28
thermarum (Miorocylloepus), 16,
40
Throsoinus3 23
81
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triangularis (Eeliohus),, 22,49 vittipennis (Stenelmis) - 21,32
trivittatus (Optiosewus) 3 18,19,44 vulnerata (Heterelm-is) 3 15,39
vca"iegata (Ancyronyx), 14,27 wcaoona (Atraotelmis), 14,35
variegatus (Dieranopselaphus)3 23,52 Zaitzevia, 21,28,64
velutina (Anchycteis), 24,52 parvula, 21,28
viennens-ls (Dryops), 21 thermae3 21,28
vittata (Dubiraph-ia)3 15,37
82
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
1. Report No.
3. Accession No.
w
4. Title BIOTA OF FRESHWATER ECOSYSTEMS IDENTIFICATION MANUAL
NO. 6 Aquatic Dryopoid Beetles (Coleoptera) of the United
States,
7. Author(s)
Brown, H. P.
9. Organization Department of Zoology
The University of Oklahoma
Norman, Oklahoma
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
is. Abstract An illustrated key is given for all known species of adult dryopoid
beetles of the United States which have aquatic stages and might be
useful as indicators of water quality. A key is also given to the
genera of larvae. For each species the known habitat and range are
given. Life histories are briefly outlined and methods for collection,
preservation, storage and identification are suggested. Two new
species, Optioservus osorkensis Collier and Optioservus sandersoni
Collier, are described, The genera included in the keys are:
Chelon&Tiidae--Chelonar-itm; Elmidae--Tribe Larini:£
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