Environmental Monitoring Series
TAXONOMY AND ECOLOGY OF
S7ENONEMA MAYFLIES
(HEPTAGENIIDAE:EPHEMEROPTERA)
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
-------
EPA-670/4-74-006
November 1974
Reprinted 1978
TAXONOMY AND ECOLOGY
OF STENONEMA MAYFLIES
(HEPTAGENIIDAE:EPHEMEROPTERA)
by
Philip A. Lewis, Aquatic Biologist
Methods Development and Quality Assurance
Research Laboratory
National Environmental Research Center
Cincinnati, Ohio 45268
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
-------
REVIEW NOTICE
The National Environmental Research Center — Cincinnati has reviewed this
report and approved its publication. Mention of trade names or commercial prod-
ucts does not constitute endorsement or recommendation for use.
-------
FOREWORD
Man and his environment must be protected from the adverse effects of pesti-
cides, radiation, noise and other forms of pollution, and the unwise management
of solid waste. Efforts to protect the environment require a focus that recognizes
the interplay between the components of our physical environment — air, water,
and land. The National Environmental Research Centers provide this multidis-
ciplinary focus through programs engaged in
• studies on the effects of environmental
contaminants on man and the biosphere, and
• a search for ways to prevent contamination
and to recycle valuable resources.
The effectiveness of measures taken to protect the biological integrity of the
Nation's surface waters is dependent upon our knowledge of the environmental
requirements of aquatic organisms and our understanding of the complex rela-
tionships that prevail in aquatic ecosystems. Mayflies are important components
of the aquatic food web and are useful water quality indicator organisms. This
manual contains a summary of available information on the pollution tolerance of
one genus of these organisms and improved keys for their identification. It was
developed to assist biologists in evaluating data collected during studies concerning
the effects of pollutants on the structure of indigenous communities of aquatic
organisms.
A. W. Breidenbach, Ph.D.
Director
National Environmental
Research Center, Cincinnati
in
-------
ABSTRACT
This manual provides keys and descriptions of all North American species of
Stenonema mayflies and consolidates information from the literature on their ecol-
ogy, environmental requirements, and pollution tolerance. Accounts of each species
include synonymy, nymphal description, collection records, and a distribution map.
The 31 species described and keyed include three new species, four new synonyms,
two resurrected species, and new combinations involving three additional species
and subspecies.
Twelve species and one subspecies are classified as intolerant to organic pollu-
tion, eight species as tolerant of mild pollution, and seven species and two sub-
species as tolerant to moderate pollution.
This reprint of the 1974 edition contains modifications
of couplets 5 - 7 of the nymphal key which make it more us-
able. Also, the adult and nymphal keys have been updated by
referring to the three new species described since 1974 in
footnotes which are cross referenced to the proper couplets.
-------
CONTENTS
Page
Foreword iii
Abstract iv
List of Figures and Tables vi
Acknowledgements vii
Introduction __ 1
Methods _ __ 1
Ecology and Life Cycle - 3
Pollution Tolerance „ 3
History of the Genus — 4
Generic Description 5
Divisions of the Genus 9
The INTERPUNCTATUM Group 9
The FEMORATUM Group 10
The PULCHELLUM Group 10
Systematics 10
Key to Mature Nymphs 11
Key to Male Images 14
Stenonema annexum 19
S. ares 19
5. bipunctatum 19
S. candidum 20
S. carlsoni 21
S. Carolina 21
S. exiguum 22
S. femoratum 22
S. floridense 23
S. fuscum 24
S. gildersleevei 24
S. integrum 25
S. interpunctatum 26
S. ithaca 27
S. lepton 28
S. hiteum 28
S. mediopunctatum 29
S. minnetonka 29
S. modestum 30
S. nepotellum 30
S. pallidum 30
S. placitum 31
S. pudicum 31
-------
CONTENTS (Continued)
Page
5. pulchellum 32
5. quinquespinum 32
5. rubromaculatum 3 3
5. rubrum 34
S:smithae 34
5. termination 35
S. tripunctatum 35
5. vicarium 36
References
37
Appendix A — Photographs 39
Appendix B — Tables 64
Appendix C — Distribution Maps 73
LIST OF FIGURES AND TABLES
Figure Page
1 Map of Ohio River Basin with Collection Sites 2
2 Drawing of Stenonema Nymph 5
3 Right Maxilla 6
4 Mandibles 6
5 Male Imago 7
6 Male Genitalia (Three dimensional view) 8
7 Male Genitalia (Microscope slide view) 8
8-188 Photographs 39
189-203 Distribution Maps 73
Table
1
2
3
4
Page
Tolerance of Species of Stenonema to Decomposable Organic Waste.. 4
List of Species of Stenonema and Synonyms of Various Authors 18
Summary of Collections Examined 64
Stenonema Collecting Sites in the Ohio River Basin 69
VI
-------
ACKNOWLEDGEMENTS
The assistance of the following biologists, who
loaned specimens during the course of this study, is
greatly appreciated: Max Anderson and Ron Ulrich,
Lower Ohio Basin Office, Evansville, IN; Ron Pres-
ton, Upper Ohio Basin Office, Wheeling, WV; Dr.
Alan Nebeker and Henry Bell, National Water Qual-
ity Lab, Duluth, MN; Robert Schneider, Southeast
Water Lab, Athens, GA, all of U.S. Environmental
Protection Agency; Dr. William Hilsenhoff and R.
Wills Flowers, University of Wisconsin, Madison;
Jay Richardson, Stroud Water Research Center,
Avondale, PA; Carl Pagel, University of Vermont,
Burlington; Dr. William Peters and Paul Carlson,
Florida A&M University, Tallahassee; John Flan-
nagan, Fisheries Research Board of Canada, Win-
nipeg; Frank Myers, Western Kentucky University,
Bowling Green; and Dr. Philip Clausen, University
of Minnesota, St. Paul. Special thanks go to Dr.
L. L. Pechuman, Cornell University Museum, Ithaca,
NY, and Dr. John E. H. Martin, Curator, Canadian
National Collection, Ottawa, Ontario, for the loan
of type material; and to Dr. Herbert H. Ross and
Donald Webb for making Dr. Burks' large collection
at the Illinois Natural History Survey, Urbana, avail-
able for examination. Much of the art work was
done by August A. Lauman, Illustrator, U.S. Public
Health Service, Cincinnati, OH.
Technical reviews of the manuscript by the fol-
lowing taxonomists are gratefully acknowledged: Dr.
William L. Peters, who deserves special thanks for
allowing me the use of his laboratory for a week of
study; Dr. George F Edmunds, University of Utah,
Salt Lake City, Dr. Steve Jensen, Southwest Mis-
souri State University, Springfield; Lee Tebo, U.S.
Environmental Protection Agency, SERL, Athens,
GA; and Jay Richardson. Philip Tsui, Florida A&M
University, Tallahassee, also offered helpful sug-
gestions.
William T. Mason, Jr., Benthos Group Leader
and Dr. Cornelius I. Weber, Chief, Biological Meth-
ods, of this office, offered many valuable suggestions
and encouragement during development of this
manual.
VII
-------
INTRODUCTION
The potential usefulness of species of Stenonema
mayflies as indicators of water quality has been rec-
ognized by many pollution biologists (Cairns et al.,
1973) but has been largely unexploited in enforce-
ment and long-term water quality studies, because
the poor state of the taxonomy of the genus pre-
vented reliable identification of the nymphs to the
species level, and information on the ecology and
pollution tolerance of the species was lacking or was
widely scattered in the technical literature and gen-
erally unavailable to practicing water pollution
biologists.
Although mayflies as a group are generally con-
sidered pollution sensitive, we have observed that
species of Stenonema vary widely in their tolerance
to pollution (Lewis, 1973). If identifications are not
carried to the species level, therefore, the use of in-
dicator organism techniques may lead to erroneous
conclusions about the quality of the water from which
the samples are collected.
This manual was prepared to provide EPA and
other aquatic biologists with updated and improved
keys and descriptions of the species in this genus and
to consolidate available information on their ecology,
environmental requirements, and pollution tolerance,
which are needed to identify the organisms and eval-
uate data collected during water quality studies.
During the course of this project, approximately
500 adults (imagos) and 1,000 nymphs were col-
lected from streams throughout the Ohio River Basin
(Fig. 1). Approximately 300 imagos were reared
from nymphs by the author. The author also exam-
ined various collections containing approximately
5,000 specimens of Stenonema nymphs and imagos,
including most of the type series for the 31 species
included in this manual. Dr. Burks' collection at the
Illinois Natural History Survey and Dr. Traver's
collection at Cornell University Museum were ob-
tained for detailed examination and photography.
The author visited the Entomological Research In-
stitute of Canada, Ottawa, and the Museum of Com-
parative Zoology at Harvard University to examine
the collections of Drs. Clemens, McDunnough,
Banks, and Walsh. Where necessary, specimens were
taken from these collections to our laboratory for
additional study. A summary of the 1,267 speci-
mens examined in detail from both private and pub-
lic collections is presented in Appendix B.
Many of the collections examined were of limited
value in checking the original descriptions because
the colors had faded from alcohol-preserved speci-
mens, the forelegs were missing from many pinned
specimens, and the genitalia were missing from some
of the type specimens. Few collections contained
sufficient reared material to form a series for com-
parative purposes. These collections were invaluable,
however, as an aid in selecting valid taxonomic char-
acters. Most of the characters used in constructing
the keys in this manual were checked against the
available type specimens or against specimens for
which the identity had been confirmed by another
Ephemeroptera specialist.
To provide a unified picture of the genus, all of
the known species of Stenonema were included in
this manual, however, the major emphasis was placed
on those species from the Ohio River Basin.
Information on the ecology, pollution tolerance,
and distribution of Stenonema presented in this man-
ual was taken from the published literature, the
author's field notes, and water quality studies con-
ducted by USEPA aquatic biologists.
METHODS
Adults were collected during the day by picking
or sweeping from vegetation, and at night from vege-
tation, buildings near street lights, lighted windows
of cottages, and auto headlights near streams. A
white sheet held in front of the headlight aided in
attracting the mayflies. In order to obtain imagos,
the subimagos were placed in 10 dram vials fitted
with cheesecloth tops and stored in a moist place
until the subimaginal skins were shed. Nymphs were
collected by hand picking, dip net, Surber sampler
(Surber, 1936), or basket sampler (Mason et al.,
1973), depending on stream conditions.
The most valuable specimens for taxonomic work
are those reared from nymphs because the imago
and subimago can be positively associated with the
nymphal exuvia. Nymphs were transported to the
laboratory and reared in plastic shoe boxes on a
gravity flow rearing apparatus (Mason & Lewis,
1970). Water temperature was maintained below
30°C during transportation and rearing. Several
rocks placed in the bottom of the tanks provided
shelter for the nymphs. Cast skins of the nymph
and subimago were preserved in the same vial as the
reared adult to reduce the possibility of incorrect
-------
FIGURE 1. LOCATION OF STENONEMA COLLECTING SITES IN THE OHIO RIVER BASIN
(Refer to Appendix B for explanation of station numbers)
-------
association. Species reared during the study were
deposited in the museum of the Illinois Natural His-
tory Survey, Urbana, Illinois.
Nymphs, and most of the subimagos, were pre-
served in 70% ethanol. However, because images
preserved in ethanol rapidly lose their color, some
of each species were dry-mounted in order to pre-
serve color patterns. The best results in pinning
were obtained by gluing the specimens to cardboard
points and using a numbering system to assure cor-
rect association.
To facilitate identification, male genitalia were
slide-mounted in Turtox CMC-S mounting medium
which cleared and stained the tissues for photograph-
ing. Other structures such as gills and mouthparts,
were mounted in Turtox CMC-9AF to obtain maxi-
mum contrast. Opaque structures were cleared by
digesting in a warm solution of potassium hydroxide
for five or ten minutes before mounting in Diaphane.1
Most structures were mounted dorsal side up. How-
ever, mandibles were mounted ventral side up to
better show the teeth on the outer canines.
Before structures to be slide-mounted were re-
moved from dried specimens, the insects were soft-
ened by placing them in a quart jar containing a
damp sponge for 24 hours. A few drops of carbolic
acid were added to the jar to prevent the growth of
mold.
Photomicrographs of slide-mounted structures were
made with a Zeiss Photomicroscope on Kodak Pana-
tomic-X black and white film. Whole specimens
were photographed with a Zeiss Tessovar photomac-
rographic unit. A camera lucida was used to make
line drawings.
ECOLOGY AND LIFE CYCLE
Because of their flattened form, Stenonema
nymphs are well adapted for clinging to rocks in
swift water. However, they develop in a variety of
habitats, ranging from lakes and large, slowly-flow-
ing rivers to swift mountain streams. Nymphs of the
FEMORATUM (TRIPUNCTATUM of other auth-
ors) group commonly inhabit the pools of small clay-
bottom streams and 5. tripunctatum tripunctatum
(Banks) is also common in lakes. Nymphs of the
INTERPUNCTATUM group are commonly found
in pools between rapids in smaller streams, in slug-
gish, rock-bottom rivers, or along the rocky shores
of lakes. Nymphs of the PULCHELLUM group
inhabit moderately swift streams, usually between
pools where there is constant current.
The greater part of the life history of Stenonema
is spent in the nymphal stage, passing through a
series of at least 25 instars that are present in the
1 Not presently available; Euparol is a good substitute.
streams in various stages of development over the
entire year (Ide, 1935). Adults emerge from the
stream as subimagos and a few hours later shed the
subimaginal skins and become images, which survive
only a few days. Some species, e.g. 5. exiguum
Traver, emerge year-round, at least in the southern
states (Berner, 1950). Others emerge during a very
short period, e.g. S. integrum (McDunnough) which
emerges from the Ohio River the last week in August
and first week in October. In the later case, the
nymphs are absent from the stream about one month
of the year, depending on the incubation period of
the eggs. The day after shedding the subimaginal
skin, the female usually deposits several thousand
eggs which hatch in 15-30 days (Needham, Traver
and Hsu, 1935).
POLLUTION TOLERANCE
Species of Stenonema reported to be intolerant to
organic pollution include Stenonema femoratum (Say),
S. interpunctatum canadense (Walker), 5. smithae
Traver, S. exiguum, S. fuscum (Clemens), 5. inter-
punctatum frontale (Banks), 5. interpunctatum inter-
punctatum (Say), 5. tripunctatum tripunctatum
(Banks), and 5. rubromaculatum (Clemens) (Gaufin,
1958; Gaufin and Tarzwell, 1952; Beck, 1954 and
1969; Neel, 1968; and Leonard, 1965). Stenonema
integrum, S. pulchellum (Walsh), 5. ares Burks, and
S. interpunctatum heterotarsale (McDunnough) were
found to be facultative in a midwestern stream
(Gaufin, 1958).
A provisional classification of the tolerance of
species of Stenonema to decomposable organic
wastes is presented in Table 1. This classification is
based on Chutter's (1972) Empirical Biotic Index in
which organisms are rated on a linear scale of water
quality in terms of tolerance to organic pollution.
Each species is allocated a quality value between
0 and 11 depending on the type of water in which
it usually occurs. The rating scheme is as follows:
Rating
Category
Definition of tolerance category
0-2 Intolerant Found only in clean water.
3-5 Facultative 1 Generally found in clean water
but able to withstand some or-
ganic enrichment if the Dissolved
Oxygen concentration remains
above 5.0 mg/1. and the pH and
water temperature are not
adversely altered.
6-8 Facultative 2 Tolerant of moderate to heavy
organic pollution accompanied
by brief periods of Dissolved
Oxygen below 5.0 mg/1., pH
changes not exceeding 2 units,
and/or temperatures exceeding
25°C.
-------
9-11 Tolerant Tolerant of gross organic pollu-
tion, generally accompanied by
Dissolved Oxygen between 5.0
mg/1. and 0.0 mg/l.,pH changes
greater than 2 units, and/or tem-
peratures above 25°C. for
extended periods. No Stenonema
fall in this category.
Because there are infraspecific differences in pollu-
tion tolerance, the table lists the quality values of
each subspecies.
TABLE 1. POLLUTION TOLERANCE OF
STENONEMA TO DECOMPOSABLE
ORGANIC WASTES (Provisional)
Species
Intolerant Facultative 1 Facultative 2
Insuf-
ficient
Data
annexum ...... - [[[
ares ................ - ..................... 5
bipiinctatum .. 1
candidum ...... 0
carlsoni .......... 1
Carolina .......... 0
exiguum ........................ ...... 3
femoratum ................................................ 8
X
floridense
fuscum s.s.
fuscum
rivulicolum .
gildersleevei
integrum s.s ........ ___ .................................. 8
integrum wabasha ...... __________ ............ - ....... 7
interpunctatum s.s ............... 4
interpunctatum
canadense ______ 1
interpunctatum frontale .... ............................
interpunctatum heterotarsale ............ ______ 7
ithaca .................................. 4
lepton .......... __________ ..........................................
luteum ............ 1
medio-
punctatum ______ 1
minnetonka .... .......................................... 6
modestum .............................
nepotellum _____ ..................... 5
palliditm ________ 1
placitum .............. ______ ................ . .....................
pndicum ........ 2
pulchellum ............................. _____ .............. 8
quinquespinum .................... 5
rubro-
maculatum .... 2
rubrum .................. .. .................................. 6
smithae ________ .............................................. 8
terminatum .......... .. .................................... 6
tripunctatum s.s ................... 5
tripunctatum
scitulum .................................... .._ ............. 7
vicarium ....... ... .................... 4
X
X
X
X
Tolerance of Stenonema nymphs to industrial
wastes and pesticides is largely unknown. Leonard
(1965) found S. tripunctatum, S. ares, S. fuscum, S.
interpunctatum and S. vicarium (Walker) tolerant of
copper and cyanide concentrations that had caused
a complete fish kill. However, Stenonema nymphs
were completely absent from the industrialized reach
of the Upper Ohio River below Pittsburgh, although
two species, S. interpunctatum and S. integrum were
common above and below this reach (Mason et al,
1971). The genus is also absent from areas effected
by acid mine drainage (Parsons, 1968) but several
species have been reported from naturally acid
streams (Bick et al., 1953). Heat pollution has also
been mentioned as a limiting factor for the nymphs
of Stenonema (Nebeker and Lemke, 1968).
The effect of siltation on the ecology of the
nymphs was demonstrated by the distribution of 5.
rubromaculatum in the Cheat River at Rowlesburg,
West Virginia, July 21, 1969 (Lewis, Unpublished).
None of the nymphs were found by the author in
silted Saltlick Creek which flows into the Cheat River
or near the east bank of the river for a distance of
2,000 feet downstream from the confluence, although
they were abundant elsewhere in the river.
HISTORY OF THE GENUS
The genus Stenonema was erected by Traver
(1933a) to include American species of Heptagen-
iidae that had previously been placed in Heptagenia,
Ecdyonurus, and other genera by a number of work-
ers, principally Needham(1901,1905), McDunnough
(1924, 1925a, 1925b, 1926, 1930, and 1933), and
Ide (1930). For a brief history of the genus Stenon-
ema see Spieth, 1947, p. 90.
Eight new species of Stenonema were described
and the male imagos of all the known species were
redescribed by Traver in The Biology of Mayflies
(Needham, et al., 1935), probably the most impor-
tant single contribution to the study of North Amer-
ican mayflies currently in print. In 1938, Spieth re-
ported that coloration is influenced by geographic
location, temperature, and bottom type so that the
color patterns in both nymphs and adults are ex-
tremely variable. In 1947, Spieth synonymized eight
previously described species of Stenonema and re-
duced seven others to subspecies on the bases of a
statistical analysis of the ratio of the length of the
second to the first fore tarsal segments and the ratio
of the length of the fore wing to the first fore tarsal
segment. Burks (1953) described three new species
of Stenonema, synonymized four others, and rede-
scribed most of the known nymphs and adults. Ber-
ner (1950) was the first to employ nymphal mouth
parts to separate species of Stenonema, a practice
commonly used in other genera, particularly the
Baetidae (Traver and Edmunds, 1968, Mueller-Lie-
-------
GENERIC DESCRIPTION
Genus Stenonema Traver
Stenonema Traver, 1933a:l73; Traver, 1933b:113;
Type-species: Stenonema tripunctatum (Banks) orig-
inally in Heptagenia.
Traver, 1935:295; Spieth 1947:88; Burks, 1953: NYMPH: Body greatly flattened Heptagenine type
154. (Fig. 2), length 6-20 mm.
CLAW
AHTEROMEDIAL PALE SPOT
ffX=~.
OCELLI
7th GILL
FRINGE OF GILL
POSTEROLATERAL SPINES
ANTENNA
FORE LEG
MIDDLE LEG
HIND LEG
CAUDAL FILAMENTS
FIGURE 2. SCHEMATIC DRAWING OF A STENONEMA NYMPH
5
-------
Head: Hypognathous, large, flattened, wider than
long; eyes dorsal, occupying posterolateral quarter
of head; labrum broad with smooth anterior margin;
maxilla (Fig. 3) with a' two segmented palpus that is
unevenly setose; inner lacinal edge with two dense
rows of simple setae (inner lacinal setae), three
slender distal lacinal denticles ( = terminal tridents),
several long slender proximal lacinal setae, and a
row of plumose lateral setae near lacinal edge; distal
margin of galea ( = crown of maxilla) with from 2-13
heavy setae that vary from plumose spines (Fig. 62)
to sturdy pectinate combs (Fig. 57), simple setae
often also present with spines on crown (Fig. 70);
asm SETOSE MASS
PECTINATE SPINES
DISTAL LACMAL DENTICLES
(TCRMMALimOIT)
INNER LACINIAL SETAE
PROXIMAL LACINIAL SETAE
LATERAL SETAE
FUSED QALEA-LACNA
PALPIFER
face usually smooth and unhanded; tibiae armed with
two rows of short spines along each margin, posterior
margin also fringed with a row of long bristles; each
tarsus of one segment, armed with a row of spines
on posterior margin; claws at distal end of tarsi, each
claw often bearing a row of pectinations near apex
(Fig. 110).
Abdomen: Depressed and tapering rearward, con-
sisting of 10 segments; terga convexly arched in mid-
dle, meeting flat sterna to form a sharp edge, pos-
terior margin of each tergum with a row of short
spines; posterolateral angles of some segments (es-
pecially 7-9) extended as sharp spines; gills dorsal,
not utilized as adhesive organs, first six gills consist
of lamellate dorsal and fibrillar ventral parts (Fig.
10), seventh gill single, slender, and lanceolate with-
out the fibrillar part (Fig. 9); caudal filaments three
in number and of about equal length.
INNER CANINES
. LACINIA MOIILIS
MOLAR SURFACE
OUTER
CANINE
LEFT
SETAE
RISNT
FIGURE 3. SCHEMATIC DRAWING OF
RIGHT MAXILLA OF STENO-
NEMA NYMPH (Ventral view)
left mandible (Fig. 4) with an outer canine bearing
a row of 4-12 teeth on inner margin, a large apical
tooth, and an additional tooth on the outer margin
just proximal to the apex (Fig. 85); an inner canine
with three large teeth at apex; and a strong pectinate
seta called a lacinia mobilis; right mandible similar
to the left except that it lacks a lacinia mobilis and
the inner tooth on the inner canine is produced as a
sharp spur (Fig. 80).
Thorax: Heavily chitinized dorsally, prothorax with
thin sharp lateral edges, meso- and metathorax fused
dorsally, each bearing a pair of wing pads; legs flat-
tened and fringed with hairs along posterior margins;
femora armed with short spines and bristles, dorsal
surface with two transverse dark bands, ventral sur-
FIGURE 4. SCHEMATIC DRAWING OF
MANDIBLES OF STENONEMA
NYMPH (Dorsal view)
MALE IMAGO: Length: Body 5-15 mm; fore
wings 6-17 mm; caudal filaments 7-20 mm.
Head: Eyes moderately large but separated on meson
by a space about the diameter of a lateral ocellus;
three ocelli arranged in a triangle occupy median
facial area; antennae each with about 25 segments,
shorter than head, basal segment (scape) short and
thick, second segment (pedicel) proportionally longer,
remaining segments very slender forming the flagel-
lum; mouthparts vestigial, forming a whitish mass
beneath the clypeus.
Thorax: Prothorax small and closely appressed to
the head, bearing a pair of forelegs; meso- and meta-
thorax strongly developed and fused together, each
bearing a pair of wings and a pair of legs; /ore legs
as long or longer than the body (Fig. 5) (except 5.
-------
>TARSI (5 SEGMENTS)
TIBIA
FEMUR
PLEURA
METANOTUM
HIND WING
SPIRACLES
STERNA
.ANTENNAE
/COMPOUND EYE
PRONOTUM
MESONOTUM
COSTAL MARGIN
BULLA
ASTIGMATIC AREA
COSTAL SPACE
SUBCOSTAL SPACE
RADIAL SPACE
APEX OF WING
MEDIAN SPACE (MA)
GENITALIA
TAILS
(CAUDAL FILAMENTS)
FIGURE 5. DRAWING OF STENONEMA RUBRUM MALE IMAGO
(From Leonard and Leonard, 1962)
-------
TELOFILUM
BASAL \ TENTH TERGUM
SPIf
LATERAL SPINES
TERMINAL
RIGHT PENIS
APICAL MARGIN
TERMINAL MARGIN
FIGURE 6. THREE DIMENSIONAL DRAWING OF MALE GEN1TALIA
OF STENONEMA IMAGO
integrum where they are slightly shorter than the
body), fore tarsus usually longer than fore tibia, first
fore tarsal segment varies from 1/3-4/5 length of
second segment (ratio of second segment to first seg-
ment 1.2-3.0), third tarsal segment about equal to
second, fourth shorter than the third, and fifth seg-
ment shortest of all, other legs much shorter than
forelegs and the tarsal segments subequal; fore wing
typical for the Heptageniidae with basal cross veins
well developed in costal area, cross veins in bulla
area sometimes crowded (Fig. 154), and stigmatic
cross veins sometimes aslant or forked but never
anastomosed; hind wing with one to four marginal
intercalaries between Cu, and Cu2 (Fig. 149, 155).
Abdomen: Consists of 10 distinct segments (llth
and 10th fused according to Needum et al., 1935),
terminating in the genitalia and two tails or caudal
filaments ( = cerci) (Fig. 5); each ring-like abdominal
segment consists of a convexly arched tergum and
a transverse sternum which meet laterally; segments
1-8 with a pair of spiracles often surrounded by dark
pigment (spiracular dots) (Fig. 143); genitalia (Fig.
6) consists of a four segmented forceps and two
L-shaped penis lobes usually deeply divided, each
lobe with a strong mesal spine ( = median titillator)
on inner margin and usually armed with an apical
and a terminal, subterminal, or discal spine (Fig. 7).
MESU SPINE
UUl SPINE
LiTEIU SPINES
BISH SPINES
FIGURE 1.
SCHEMATIC DRAWING OF
MALE GENITALIA OF STENO-
NEMA IMAGO (Dorsal view)
-------
FEMALE IMAGO: The female resembles the
male in general appearance and coloration except
that the abdominal coloration is often obscured by
the yellowish eggs visible through the integument.
Morphological differences of the female include
smaller and more widely separated eyes, shorter
forelegs, subequal tibia and femur, tarsi shorter than
tibia, tarsal segments nearly subequal, cross veins
and dark pigment in bulla region of fore wing and
dark margin on hind wing more variable than in
male, and posterior margin of ninth sternum rounded,
without prominant process (Fig. 130).
SUBIMAGO: Practically identical to images ex-
cept for a dull grey appearance, legs and tails shorter,
and wing borders more pubescent than images; geni-
talia not fully developed.
DISCUSSION
Nymphs of Heptagenia, Epeorus, Cinygma and
Traverella are sometimes confused with Stenonema.
All of these except Traverella have plate-like seventh
gills, and Traverella is distinguished by the head
capsule not covering the mandibles and by the bi-
lamillate gills (segments 1-5) the margins of which
are finely dissected to form numerous long filaments.
The arrangement of spines and setae on the maxillae
also serves to differentiate Traverella and Heptagenia
nymphs from Stenonema. In Traverella the crown
of the maxilla is thickly crowded with long setae with
no spines, there is only one small distal lacinal den-
ticle, and there are no lateral setae. In many Hepta-
genia the lateral setae are scattered over the lacinal
face instead of being arranged in a row and there
are 9 or more (usually more than 13) heavy comb-
like spines the width of the crown of the maxilla
(Fig. 53). Mandibles of all Heptagenia nymphs have
more than one lacinia mobilis (Fig. 79). The vesti-
gial median caudal filament of Epeorus nymphs also
serves to distinguish them from Stenonema.
Adult males of Stenonema can be separated from
Heptagenia only by an examination of the genitalia.
In Stenonema the penis lobes are more L-shaped than
in Heptagenia except for some of the INTERPUNC-
TATUM group where the penis lobes are armed with
lateral spines not found in Heptagenia. The ratio
of the second fore tarsal segment to the first fore
tarsal segment in Stenonema falls between 1.0 and
3.0 whereas in Epeorus, Rhithrogena, and most of
the Heptagenia the ratio is either less than 1.0 or
greater than 3.0. See Burks (1953, p. 151) for
diagnostic keys to the genera of Heptageniidae and
illustrations of the genitalia.
Females of Stenonema are difficult to distinguish
from Heptagenia unless association with males can
be established. However, Koss (1968) has reported
diagnostic differences in egg morphology.
DIVISIONS OF THE GENUS
Traver (1933a, 1933b) divided the genus into
three groups based on the structure of the nymphal
gills: INTERPUNCTATVM, VICARWM, and
TRIPUNCTATUM. She later (1935) changed the
name of VICARWM to PULCHELLUM. Burks
(1953) recognized seven groups in this genus based
mostly on adult characters. The divisions employed
in this paper are easily recognized in the eggs,
nymphs, and images, and are probably sufficiently
different to be considered as distinct subgenera. Char-
acteristics of the species groups are summarized in
tables following the keys.
The II\TERPUI\CTATUM Group1
Nymph: Nymphs of the INTERPUNCTATVM
group are characterized by the pointed gills on ab-
dominal segments 1-6 (Fig. 8) and the lack of a
fringe of setae on the margins of the seventh gill
(Fig. 9). The crown of each maxilla has 8-13 heavy
pectinate spines but no setae (Fig. 55). There are
15-45 lateral setae along the lacinal edge of each
maxilla. The posterolateral angles of abdominal
segments 1-6 are not produced as spines.
Male imago: Males are characterized by the spines
on the lower lateral margins (lateral spines) of the
penis lobes (Fig. 169) (except in S. Carolina), and
by the black-margined cross veins in the basal por-
tion of the costal, subcostal, and radial spaces of
the fore wings. These black margins are wider in
the middle of the cross veins than at the ends (Fig.
148). Two or three cross veins in the radial inter-
space below the bulla are usually connected by a
black pigmented line. If these veins are not con-
nected, there is a black dot on each (Fig. 152).
Female imago: Females are similar to the males
except for the usual dimorphic differences and can
be identified only by association with the males or
by a study of the egg morphology. The eggs differ
from the other two groups and Heptagenia in pos-
sessing polar caps (Koss, 1968).
DISCUSSION
The INTERPUNCTATUM group consists of
seven species: S. gildersleevei Traver, S. pallidum
Traver, 5. Carolina (Banks), S. candidum Traver, S.
minnetonka Daggy, S. interpunciatum, and 5. flori-
dense Lewis, a new species from the Blackwater
River, Florida. Although numerous other species
have been described, Spieth (1947) synonymized
most of them with S. interpunctatum or relegated
them to subspecies (see Table 2).
'The INTERPUNCTATUM group was described as a new genus,
Stenacron Jensen (Proc. Ent. Soc. Wash. 76:225-228. 1974), as this
manual went to press.
-------
The FEMORATVM Group
Nymph: Nymphs of the FEMORATVM group are
characterized by rounded gills on abdominal seg-
ments 1-6 (Fig. 10). The seventh gill is fringed and
contains a single trachea which may branch once
near the base (Fig. 11). The crown of each maxilla
bears two to four pectinate spines followed by 2-35
setae (Fig. 58). Along the lacinal edge of each max-
illa are 20-40 lateral setae (Fig. 61). Large postero-
lateral spines are present on segments 3-9 (Fig. 39).
Male imago: Images are easily recognized by the
three dark transverse marks at the posterior margins
of terga 2-8 (Fig. 127). The cross veins in the bulla
region are crowded but never connected by a black
line (Fig. 154). Lateral spines are lacking on the
penis lobes, and the posterior (apical) margins are
nearly straight (Fig. 171).
Female imago: Females are similar to males ex-
cept for the usual secondary sexual characteristics.
Also, females of the two species tend to have less
crowding of the cross veins in the bulla region and
less pigment in the apical margin of the hind wing
than do the males. The eggs lack both polar caps
and sperm guide hoods (Koss, 1968).
DISCUSSION
In this group, Spieth (1947) recognized a single
species consisting of three subspecies. However,
based on his study of adults, Burks (1953) recog-
nized 5. femoratum and S. tripunctatum as separate
species. Both species are common in small creeks
in southern Ohio and Kentucky, and show little evi-
dence of intergradation. There are distinct morpho-
logical differences between the two species in the
adults and nymphs, and Koss (1968) has shown that
there are obvious differences in the eggs. A third
phenon (5. scitulum Traver) is presently considered
a subspecies of 5. tripunctatum, for reasons men-
tioned under the discussion of that species.
The PVLCHELLVM Group
Nymph: Nymphs of the PULCHELLUM group
are characterized by the truncated gills on segments
1-6 (Fig. 12) and the heavily fringed seventh gill
which lacks tracheae (Fig. 13). Each maxilla bears
2-9 spines and 0-50 setae on the crown and 15-45
lateral setae along the lacinal edge. Development of
spines at the posterolateral angles of the abdominal
segments varies from species to species.
Male imago: Males are characterized by the ab-
sence of a black line or dark pigmented spot con-
necting the cross veins in the bulla region of the
fore wing, the absence of lateral spines on the penis
lobes, and the absence of three dark transverse marks
at the posterior margin of abdominal terga 2-8 (there
may be one or two dark transverse marks or a dark
band).
Female imago: Females are similar to the males
except for the usual sexual characteristics. It is pres-
ently impossible to identify many of the females to
species, but the females of this group can be sep-
arated from the other two groups by characters used
in the key and verification tables, and by the eggs,
which differ from those of the other two groups and
from Heptagenia in possessing sperm guide hoods
(Koss, 1968).
DISCUSSION
The taxonomic status of several species in the
PULCHELLUM group needs further clarification.
The synonymies listed in Table 2 give some idea as
to the scope of the problem.
SYSTEMATICS
The taxonomy of the genus has been confused
because past keys and descriptions have not em-
ployed reliable characters. Descriptions of new
species have been based on phenotypic differences
in the adults, while the nymphs have generally been
ignored. Many of the descriptions of adults and
nymphs have been based almost entirely on colora-
tion and size differences, both of which may be ex-
tremely variable within a given species (Spieth, 1938,
1947). Nymphs of at least ten species are either
unknown or have not been positively associated with
the images.
As with most mayflies, coloration varies with the
environment, season, and geographical distribution
of the species (Spieth, 1938), and has been overem-
phasized in the taxonomy of both images and
nymphs of the genus Stenonema. Dorsal color pat-
tern is even less reliable for nymphs than for adults,
but ventral maculation seems to be consistent. Since
color patterns are often obscured by generalized
melanistic shading (Spieth, 1947), coloration is used
as a key character in this manual only when found
to be consistent and when no other differences could
be found to separate the species.
More reliable imaginal characters include: the
shape and arrangement of spines on the penis lobes,
the arrangement of cross veins in the bulla region
of the fore wings, the ratio of the first fore tarsal
segment to the length of the fore wing, and the ratio
of the length of the first fore tarsal segment to the
length of the second (fore tarsal ratio). It should be
noted that the fore tarsal ratio will be proportionately
greater on specimens that are killed while in the
process of shedding the subimaginal skin, because the
legs do not expand to normal size until after the
subimaginal skin has been completely shed.
10
-------
Reliable diagnostic characters for nymphs include:
the number and arrangement of spines and setae on
the maxillae, the number of teeth on the inner mar-
gin of the outer canine of the mandible, the shape
of the abdominal gills, the presence or absence of
pectinations near the apex of the tarsal claws, and
presence or absence of spines on the posterolateral
angles of abdominal segments. Some of these char-
acters, however, are useful only in separating later
instar nymphs, and the keys must be used with cau-
tion with less mature specimens.
An attempt was made to keep nomenclatural
changes in this manual to a minimum even though
the genus needs a complete revision. The author's
study of museum collections and reared specimens
mostly from the Ohio River Basin has resulted in
the discovery of four new synonyms, three new
species, and several other taxonomic changes which
are summarized here and discussed in detail follow-
ing the description of the species involved.
After a careful study of the type series of S. areion
Burks, the species was considered synonymous with
S. interpunctatum canadense in harmony with Spieth's
(1947) diagnosis of the INTERPUNCTATUM
group. Based on reared specimens and study of the
type series of S. scitulum Traver, the author consid-
ered this taxon a subspecies of S. tripunctatum rather
than S. femoratum; and S. femoratum is considered a
valid species distinct from S. tripunctatum. Stenon-
ema varium Traver is synonymized with 5. rubrum
(McDunnough), since no significant differences were
observed between the types. Rearing confirmed
Burks' suggestion that S. metriotes Burks is a syno-
nym of 5. integrum. The author considered the
resurrection of 5. placitum (Banks) and 5. pallidum
necessary because the arrangement of spines on their
genitalia is distinctly different from that on the geni-
talia of S. terminatum (Walsh) and S. interpunctatum
respectively.
A comparison of the fore tarsal ratios of S. exi-
guum and S. alabamae Traver convinced the author
that 5. alabamae is a junior synonym of S. exiguum.
Based on a comparison of the male genitalia of its
types, 5. rivulicolum (McDunnough) is considered a
junior synonym of 5. fuscum rather than S. vicarium.
The author believes that S. modestum (Banks) be-
longs in the genus Stenonema as Burks (1953) in-
dicated. Three new species Stenonema quinques-
pinum Lewis, S. carlsoni Lewis and S. floridense
Lewis were described as a result of this study (Lewis,
1974). Species of Stenonema recognized by the
author and synonymous species of other authors are
presented in Table 2 following the keys. The sys-
tematic list of species given by Edmunds (1962) was
used as the basis for this manual.
Structures used in the following keys are shown
in Figures 2 through 7. Summary tables of diagnostic
characters which follow the keys and the photo-
graphs should be used in conjunction with the keys.
The nymphs of S. modestum, placitum, and lepton
are not known. Although all the known species of
Stenonema are included in the following keys, they
should be used with caution outside the Ohio River
Basin, because as yet undescribed species are com-
monly encountered in other parts of the country and
the extent of geographical variation within the various
species is unknown.
Key to the mature nymphs
1. Gills on abdominal segments 1-6 pointed at
apices (Fig. 8); 8-13 pectinate spines on crown
of maxilla (Fig. 57)
INTERPUNCTATUM GROUP -- 3
Gills on abdominal segments 1-6 truncated or
rounded at apices, 2-9 pectinate spines on crown
of maxilla 2
2. Gills on abdominal segments 1-6 rounded at
apices (Fig. 10); 2-5 pectinate spines on crown
of maxilla (Fig. 58); seventh gill with a single
or branched trachea (Fig. 11)
FEMORATUM GROUP 9
Gills on abdominal segments 1-6 distinctly
truncated at apices (Fig. 12); 2-9 pectinate
spines on crown of maxilla (Fig. 62); seventh
gill without tracheae (Fig. 13)
PULCHELLUM GROUP 10
3. Each maxilla with 30 or more lateral setae
(Fig. 60) 4
Each maxilla with less than 30 lateral setae
5
4. Crown of maxilla with 8-10 pectinate spines
(Fig. 60); sterna 7-9 with dark bands or spots
at lateral margins S. minnetonka
Crown of maxilla with 11-13 heavy pectinate
spines (Fig. 59); sterna 7-9 without dark bands
or spots . S. gildersleevei
5. Crown of maxilla with 11-13 pectinate spines
(Fig. 57) 5. pallidum
Crown of maxilla with 7-10 pectinate spines
(Fig. 56) 6
6. Dorsum nearly uniform brown, without pale
longitudinal streaks (Fig. 17), venter entirely
pale 5. Carolina
Dorsum with longitudinal pale streaks the length
of abdomen (Fig. 14), usually with some distinct
dark markings on posterior sterna (Fig. 35) ._ 7
11
-------
7. Inner margin of outer canine of left mandible
with 8 teeth (Fig. 82) 5. candidum
Inner margin of outer canine with 5-7 teeth
(Fig. 85) 8
8. Mid-dorsal pale streaks continuous or nearly so,
widely distributed S. interpunctatum
Mid-dorsal pale streaks discontinuous, distri-
bution limited to naturally acid streams of the
Gulf States S. floridense
9. Two pectinate spines on crown of maxilla (Fig.
58); anterior margin of head emarginate (Fig.
18), posterior half of sternum 9 usually brown
(Fig. 38) 5. femoratum
Three to five pectinate spines on crown of max-
illa (Fig. 61); anterior margin of head not
emarginate, four black spots on sternum 9 (Fig.
39) 5. tripunctatum
10. Crown of maxilla with pectinate spines but no
setae (Fig. 62) 11
Crown of maxilla with setae in addition to pec-
tinate spines (Fig. 75) 19
11. Posterolateral angles of abdominal segments 3,
4, or 5-9 extended as spines (Fig. 42) 12
Posterolateral angles of abdominal segments 7
to 9 only extended as spines (Fig. 49) 14
12. Crown of maxilla with 7 or 8 pectinate spines
(Fig. 64) S. carlsoni
Crown of maxilla with 3 to 6 pectinate spines
13
13. Inner margin of outer canine with 7 or 8 teeth
(Fig. 108); maxilla with 25-30 lateral setae
(Fig. 68) S. nepotellum
Inner margin of outer canine with 5 or 6 teeth
(Fig. 90); maxilla with 20-25 lateral setae
S. bipunctatum
14. Sterna 2-7 without dark markings (Fig. 50),
claws often pectinate 15
Sterna 2-7 with distinct dark markings (Fig.
48), claws not pectinate 18
15. Anastomosed large white spots forming a pale
band across base of wing pads (Fig. 23); if
band not evident in pale specimens then claws
not pectinate 16
Base of wing pads without anastomosed spots
or pale band {a few small spots may be present),
claws pectinate in pale specimens 17
16. Sterum 9 with dark lateral margin (Fig. 50),
claws not pectinate 5. quinquespinum
Sterum 9 dark only at posterolateral angles,
claws pectinate (Fig. 117) S. exiguum
17. Tergum 7 mostly white, claws pectinate (Fig.
114) (Note 1) 5. pulchellum
Tergum 7 mostly dark, claws not pectinate (Fig.
115) S. ares
18. Transverse brown band present at middle of
sterna 4-8 (Fig. 41) 5. ithaca
Brown stripes and spots present on sterna 4-8
but not forming a transverse brown band (Fig.
48) S. termination
19. Posterolateral angles of abdominal segments 3-
9 extended as spines (Fig. 47) 20
Posterolateral angles of abdominal segments 7-
9 only extended spines (Fig. 51) 26
20. Posterior fourth to half of sterna 7 and 8 dark
brown or black (Fig. 45) 21
Posterior fourth of sterna 7 and 8 pale (Fig.
44) 23
21. Black posterior band on sternum 8 extending
forward in sublateral areas to middle of sternum
(Fig. 45), claws pectinate (Fig. Ill)
(Canada) 5. luteum
Black band at posterior margin of sternum 8
the same width across sternum (Fig. 46), claws
not pectinate (Fig. 109) 22
22. Entire posterior half of sternum 9 dark brown
(Fig. 47); maxilla with 15-25 lateral setae
(Fig. 72) S. vicarium
Only posterolateral angles of sternum 9 dark
brown (Fig. 46); maxilla with 25-35 lateral
setae (Fig. 75) 5. fuscum
23. Less than 10 crown setae on maxilla (Fig. 78)
(If venter lacks dark markings go back to
couplet 12.) S. mediopunctatum
More than 10 crown setae on maxilla (Fig. 77)
24
24. Claws without pectinations (Fig. 118); sterna
marked as in Figure 43 (Note 2) S. pudicum
Claws with pectinations (Fig. Ill); sterna
marked as in Figure 40 or 48 25
25. Maxilla with 2-4 pectinate crown spines and
less than 25 lateral setae (Fig. 77); 6 or 7 teeth
on inner margin of outer canine (Fig. 98) (Wis-
sonsin) S. luteum
Maxilla with 4-7 pectinate crown spines and
20-35 lateral setae (Fig. 76); 8 or 9 teeth on
inner margin of outer canine (Fig. 103)
S. rubromaculatum
Note 1 - S. MER1RIVVLANVM Carle and Lewis (Ann. Ent. Soc.
Am. 71:285-288, 1978) keys here also.
Note 2 - A new species from Tennessee being described by Lewis
(Proc. Ent. Soc. Washington, in press) also keys here.
12
-------
26. Maxilla with 2 or 3 pectinate spines (Fig. 70);
V-shaped pale mark covering terga 7, 8 and 9
(Fig. 25) _ S. integrant
Maxilla with 4-6 pectinate spines; no V-shaped
pale mark on terga 7-9 —. -- 27
27. Sterna 8 and 9 usually without dark markings
(Note 3) - - .S. annexuni
Sterna 8 and 9 with dark markings (Figs. 51 &
52) - 28
Note .1 .V. RI/'UNCTATUM with 1 or 2 crown setae (Huwers
and HilsenhorT. The Cireal lakes Entomologist X:2I3, IV7S) also
keys here.
Characters for separating nymphs to species groups:
28. Maxilla with 15-25 setae on crown (Fig. 74);
V-shaped dark brown mark on sternum 9 with
vertex at anterior margin (Fig. 51) ... S. nibntm
Maxilla with 30-40 setae on crown (Fig. 73);
lateral margins of sternum 9 dark, the bands
sometimes meeting at anterior margin (Fig. 52)
(Note 4) . S. smithae
Note 4 - .V. Al.lKiiHFNn-.NSI. Carle [Ann. P.m. Sot. Am.
70:711-714. 1977) also keys here.
Character
Gills 1-6
7th gill
Claws
Tracheae in 7th gill
Pectinate spines on maxillae
Crown setae
Characters of INTERPUNCTATUM group
Character ^
"o
a
-------
Characters of PULCHELLUM group numphs:1
Species
5. annexum
S. ares
S. bipunctatum
S. carlsoni
S. exiguum
S. fuscum
S. integrum
S. ithaca
S. luteum
S. mediopunctatum
S. nepotellum
S. pudicum
S. pulchellum
S. quinquespinum
S. rubromaculatum
S. rubrum
S. smithae
S. termination
S. vicarium
Crown of maxilla
pectinate
spines
4 or 5
3 or 4
3 or 4
7 or 8
4-9
2-4
2 or 3
4-6
2-4
4-6
4-6
5-8
4-6
4 or 5
4-7
4-6
4-6
4-6
2-4
setae
25-30
0
0
0
0
10-40
30-50
0
30-40
1-5
0
20-40
0
0
30-50
15-25
30-40
0
10-25
Teeth on
— inner mar-
gin of out-
ter canine
6 or 7
6 or 7
5 or 6
8-10
6-8
7 or 8
5-8
6 or 7
6 or 7
7 or 8
7 or 8
10 or 11
6 or 7
7 or 8
8 or 9
7-9
7 or 8
5-7
7 or 8
Lateral
setae on
maxilla
20-25
15-25
20-25
25-45
18-25
25-35
15-25
15-26
18-25
30-40
25-30
30-40
15-30
20-30
20-35
15-25
20-30
13-26
15-25
Postero-
lateral
spines on
abdominal
segments
7-9
7-9
4?-9
3-9
7-9
3-9
7-9
7-9
3-9
3-9
5-9
3-9
7-9
7-9
3-9
7-9
7-9
7-9
3-9
Wide dark
posterior
margin on
sterna
no
no
no
no
no
yes
no
no
yes
no
no
no
no
no
no
no
no
no
yes
Claws
pectinate2
yes
no
yes?
no?
yes
no
no
no
yes
no
yes
no
yes
no?
yes
yes
yes
no
no
1 Nymphs of S. lepton, S. modestum, and S. placitum not known.
2 Two minute pectinations near tip of the claw.
Key to male imagos
1. Penis lobes of genitalia (except 5. Carolina) with
lateral spines (Fig. 169); basal cross veins of
fore wings in costal, subcostal, and radial spaces
thickened and with dark margins in middle; 2
or 3 cross veins below bulla connected by a
black dash or with a black spot in the middle
of one or more of the veins (Fig. 150)
INTERPUNCTATUM GROUP . 3
Penis lobes of genitalia without lateral spines
(Fig. 183); basal cross veins in costal, subcostal,
and radial spaces without dark margins in mid-
dle and without black dash or dots below bulla
(Fig. 162) 2
2. Posterior margins of abdominal terga 2-8 with
3 black marks, a median dot, and a pair of
submedian, transverse dashes (Fig. 127)
FEMORATUM GROUP ____..' "To
Posterior margins of abdominal terga marked
otherwise
----- PULCHELLUM GROUP .... H
3. Outer lateral margins of penis lobes with a
cluster of large spines (Fig. 169) 4
Outer lateral margins of penis lobes without a
cluster of large spines (Fig. 167), extremely
minute spines may be present (Fig. 170) 9
4. Penis lobes with terminal or subterminal spines
(Fig. 168) 5
Penis lobes with discal spines (Fig. 165) (See
Fig. 6) 6
5. Venter of abdomen with a median, longitudinal,
dark line extending from anterior to posterior
ends, this line slightly widened and with a nar-
row interruption at posterior margin of each
sternum — S. gildersleevei
Venter not as above, usually entirely pale or
faint dark marks at posterior margin of some
sterna.... (ssp. canadense) S. interpunctatum
6. Two or more large axial spines on penis lobes
(Fig. 166) S.floridense
No axial spine on penis lobes (Fig. 165) 7
14
-------
7. Apical spine of each penis lobe, if present,
smaller than discal spine (Fig. 165); black
streak often present on pleuron ventral to fore
wing base (Fig. 124) 8
Apical spine of each penis lobe larger than
discal spine; dark spiracular dots present on
abdominal terga; black line on face ventral to
antennal sockets (as in Fig. 125); no black
streak on pleuron ventral to fore wing base
—. 5. minnetonka
8. Either with black dash connecting cross veins
below bulla in fore wing (Fig. 150), with spi-
racular dots present (Fig. 124), or with dark
pleural streaks present.— (ssp. interpunctatum,
frontale, and heterotarsale) ... S. interpunctatum
Black dash not connecting cross veins below
bulla in fore wing, spiracular dots and dark
pleural streaks absent (Fig. 120) S. pallidum
9. Penis lobes with terminal or subterminal spines
(Fig. 167); black spiracular dots on terga 4-8
(Fig. 121); black dashes on face below antennae
S. candidum
Penis lobes without terminal or subterminal
spines (Fig. 170) but usually with discal spines;
spiracular dots and black marks on face usually
absent 5. Carolina
10. Cross veins in bulla region of fore wing crowded
in first 6 interspaces (Fig. 153); discal spine of
penis lobe about same size as apical spine (Fig.
172) 5. femoratum
Cross veins in bulla region of fore wing crowded
in just 3 interspaces (Fig. 154); discal spine on
penis lobe much larger than apical spine and
broadly triangular (Fig. 171) „_ S. tripunctatum
11. Cross veins of fore wing crowded in first 6
spaces (Fig. 158) 12
Cross veins of fore wing crowded in first 3
spaces or not crowded at all (Fig. 163) 13
12. Abdomen dark yellow brown to medium brown;
posterior 1A or more of terga 2-8 dark brown,
this band sometimes nearly reaching anterior
margin on meson (Fig. 136 and 137)
S. pudicum
Abdomen light yellow brown to white with nar-
row brown band at posterior margin of each
terga 2-8, this band usually narrowest at meson
(Fig. 130) S.carlsoni
13. Terminal, subterminal, or discal, spines present
on penis lobes 14
Terminal, subterminal, and discal spines of
penis lobes absent 31
14. Apical spine on each penis lobe larger or about
the same size as terminal, subterminal, or discal
spine (Fig. 178) 15
Apical spine definitely smaller than terminal,
subterminal, or discal spine (Fig. 184) 23
15. At least posterior half of terga 2-6 brown in
mid-dorsal area; a wide, dark brown band at
posterior margin (Fig. 135) (Note 5) S. vicarium
Dark band at posterior margin of terga 2-6
limited to a narrow line less than l/5th width
of terga _„ 16
16. Dark gray longitudinal line on meson of terga
3 and 6 (Fig. 140); cross veins in bulla region
and beyond arranged serially across wing usu-
ally forming elongate cells (Fig. 160); spiracular
marks, if present, consist of black oblique
streaks (Fig. 139) S.integrum
No dark gray longitudinal line on meson of
terga 3 and 6; cross veins in bulla region and
beyond not arranged serially across wing (Fig.
162); spiracular marks, if present, consist of
black dots (Fig. 143) 17
17. Hind wing tip dark margined (Fig. 157 and
159) 18
Hind wing tip not dark margined (Fig. 164)._19
18. Spiracular dots present (Fig. 146).— 5. smithae
Spiracular dots absent S. exiguum
19. Spiracular dots present (Fig. 143) 20
Spiracular dots absent S. termination
20. Posterior margins of terga 2-8 with small black
dash on meson as in Fig. 141
5. mediopunctatitm
Posterior margins of terga 2-8 with narrow
black crossline 21
21. Fore tarsal ratio 1.1-1.3; spines on penis lobes
as in Fig. 174 5. modestum
Fore tarsal ratio 1.7-2.1 22
22. Penis lobes with subterminal spine smaller than
apical spine (Fig. 178); cross veins not crowded
in bulla region (Fig. 156); mesoscutellum en-
tirely white S. pulchellum
Penis lobes with subterminal spine about same
size as apical spine (Fig. 185); cross veins in
bulla region with 2 or 3 veins present in at
least two intervals (Fig. 164); only tip of mesos-
cutellum white S. rubrum
23. At least posterior half of terga 2-6 shaded with
brown in mid-dorsal area (Fig. 131 and 147)..24
Abdominal terga pale except dark band at pos-
terior margin covering much less than V4th of
segment (Fig. 138) 25
15
Note 5 - 5. ALLEGHEN1ENSE Carle (Ann. Ent. Soc. Am
70:711-714. 1977) also keys here.
-------
24. Fore wing with many cross veins forming short
cells (Fig. 161); mesonotum and abdomen with
distinct reddish brown cast _ ......... ------- S. ithaca
Fore wing normal with some elongate cells;
mesonotum deep brown but without reddish
cast (Note 6) _________________________________ ..... S. fuscum
25. Posterior margins of terga 2-8 with a pair of
short dashes (Fig. 133) ______________ S. bipunctatum
Posterior margins of terga 2-8 with narrow
black lines or diffuse reddish band ---------------- 26
26. Spiracular marks, if present, consist of oblique
grey dashes (Fig. 142) __________________________________ 27
Spiracular black dots present ------------------------ 28
27. Penis lobes boot-shaped with subterminal spine
(Fig. 188); mesonotum light yellow-brown; nar-
row black line at posterior margins of terga
2-6 (Fig. 144); oblique grey dashes may be
present in spiracular area (Fig. 142).__.S. luteum
Penis lobes oval with large discal spine (Fig.
180); mesonotum dark brown; diffuse reddish
band at posterior margins of terga 2-6; spiracu-
lar marks not present _____________________ 5. placitum
28. Narrow brown band at apex of hind wing (Fig.
138) (Note 7) S. quinquespinum
Hind wing without narrow brown band at apex
(Fig. 162) 29
29. Large spine on penis lobe in discal position
(discal spine) (Fig. 175) S.annexum
Large spine on penis lobe in terminal position
(terminal spine) (Fig. 183) 30
30. Fore tarsal ratio more than 2.0; cross veins in
bulla region moderately crowded
S. rubromaculatum
Fore tarsal ratio less than 2.0; cross veins in
bulla region not crowded (Fig. 162)
„__ 5. nepotellum
31. Abdominal terga 3-8 each with a pair of sub-
median transverse black streaks at posterior
margin (Fig. 129); mesonotum reddish brown;
fore tarsal ratio about 2.0 S. ares
Abdominal terga 3-8 each with an unbroken
narrow black line across posterior margin; fore
tarsal ratio about 1.2 to 1.5 _5. lepton
Note 6 - A new species from Tennessee being described by Lewis
(Proc. Ent. Soc. Washington, in press) also keys here.
Note 7 - S. MERIR1VULANUM Carle and Lewis (Ann. Ent. Soc.
Am. 71:285-288, 1978) also keys here.
Characters for separating adults to species groups:
Character
Lateral spines on penis
Cross veins in fore wing crowded
Black dash or dot below bulla
Costal cross veins of fore wing dark margined
Markings on posterior margin of terga 1-8
Eggs:
with polar caps
with sperm guide hoods
INTERPUNCTATUM
yes (except
Carolina)
usually
yes
yes
dark line
yes
no
Group
FEMORATUM
no
yes
no
no
3 dashes
no
no
PULCHELLUM
no
variable
no
no
variable
no
yes
Characters of FEMORATUM group adults:
Character
5. femoratum
S, t. tripunctatum
S. t. scitulum
Cross veins in bulla region
crowded in
Dark band on hind wing-tip
Length of forewing:
Male
Female
1st 6 spaces
wide
10-13mm
13-17mm
1st 3 spaces
absent
10-13mm
13-17mm
1st 3 spaces
narrow
8-10mm
9-11mm
16
-------
Characters of INTERPUNCTATUM group adults:
Character
Black mark on face
below antennae
Dark median
line on sterna
Pleural streaks
Stigmal dots
Black spot or dash below
bulla of fore wing
Penis lobes:
Terminal spine
Discal spine
Lateral spine
Apical spine
Axial spine
Fore tarsal ratio
absent
absent
absent
absent
spot
absent
present
absent
present
absent
1.8-2.0
dash
absent
absent
present
absent
present
absent
minute
minute
absent
2.0
absent
absent
absent
absent
dash
absent
present
present
minute
present
2.0-2.4
line
present
absent
obscure
dash
present
absent
present
absent
absent
1.5-2.5
variable
absent
variable
variable
dash
variable
variable
present
variable
absent
1.1-3.5
line
absent
absent
present
dash
absent
small
present
large
absent
2.0
dash
absent
absent
absent
spot
absent
present
present
minute
absent
2.0
Characters of PULCHELLUM group adults:
Species
S. annexum
S. ares
S. bipunctatum
S. carlsoni
S. exiguum
S. juscum
S. integrum
S. ithaca
S. lepton
S. luteum
S. mediopunctatum
S. modestum
S. nepotellum
S. placitum
S. pudicum
S. pulchellum
S. quinquespinum
S. rubromaculatum
S. rubrum
S. smithae
S. terminatum
S. vicarium
Cross veins in
bulla region
2 or 3
1 or 2
1 or 2
3-6
1 or 2
1-3
1-3
1, 2, or 3
1 or 2
1 or 2
1 or 2
1 or 2
1 or 2
1 or 2
3-5
1 or 2
1 or 2
2 or 3
1, 2, or 3
1-3
1 or 2
2-3
Spines1 on
penis lobes
A,D
A
A, T
A
A,T
A, T
A,T
A,T
A
A,T
A, T
A,T
A,T
A, D
A, T
A, T
A,D
A,T
A, T
A,T
A,T
A, T
Stigmal
dots
present
absent
absent
obscure
absent
obscure
present
obscure
absent
absent
present
present
present
absent
obscure
present
present
present
present
present
absent
absent
Hind wing
tip dark
no
no
no
yes
yes
no
yes
no
yes
no
no
no
no
no
yes
no
yes
no
no
yes
no
no
Fore tarsal
ratio
1.6-1.9
2.0
1.5
1.5-2.0
1.3-1.9
2.0-3.0
1.3-2.0
2.0-2.3
1.2-1.5
2.1
1.5-1.8
1.1-1.3
1.5-2.0
1.8
1.5-2.0
1.7-2.1
1.6
1.6-2.2
1.7
1.7-2.1
1.5-2.5
2.5-4.0
Posterior margin of
tergites 2-7
narrow line
pair short dashes
pair short dashes
narrow line
narrow line
segments Vz brown2
narrow line
segments all brown2
narrow line
narrow line
median dash
narrow line
narrow line
diffuse band
wide band
narrow line
narrow line
narrow line
narrow line
narrow line
vague band
wide band
i A = apical or subapical, D = discal, T = terminal or subterminal.
2 In median area.
17
-------
TABLE 2. LIST OF SPECIES OF STENONEMA AND SYNONYMS OF VARIOUS AUTHORS
Authors
Lewis
INTERPUNCTATUM GROUP
S. Carolina (Banks)
5. candidum Traver
S. floridense Lewis
5. gildersleevei Traver
S. interpunctatum canadense
S. interpunctatum canadense
S. interpunctatum canadense
S. interpunctatum frontale
S. interpunctatum frontale
S. interpunctatum frontale
S. interpunctatum heterotarsale
S. interpunctatum interpunctatum
S. interpunctatum interpunctatum
S. interpunctatum interpunctatum
S. minnetonka Daggy
S. pallidum Traver
FEMORATUM GROUP
S. femoratum (Say)
S. tripunctatum tripunctatum
S. tripunctatum tripunctatum
S. tripunctatum scitulum
PVLCHELLUM GROUP
S. annexum Traver
S. ares Burks
S. bipunctatum (McD.)
S. carlsoni Lewis
S. exiguum Traver(3)
5. exiguum
S. fuscum fuscum (Clemens)
5. fuscum rivulicolum
S. integrum integrum
S. integrum integrum
S. integrum integrum
S. integrum wabasha
S. ithaca (Clemens & Leonard)
5. lepton Burks
S. luteum (Clemens)
5. mediopunctatum (McD.)
S. modestum (Banks)
S. nepotellum (McD.)
S. placitum (Banks)
S. pudicum (Hagen)
5. pulchellum (Walsh)
S. quinquespinum Lewis
S. rubromaculatum (Clemens)
S. rubritm (McD.)
S. rubrum
S. smithae Traver
S. terminatum (Walsh)
S. vicarium (Walker)
Burks
Carolina
candidum
—
gildersleevei
canadense (Walker)
canadense
areion Burks
frontale (Banks)
frontale
canadense
heterotarsale (McD.)
interpunctatum (Say)
heterotarsale (McD.)
canadense
minnetonka
—
femoratum
tripunctatum (Banks)
—
—
—
ares
bipunctatum
pudicum (Hagen)
—
—
fuscum
vicarium
integrum (McD.)
integrum
metriotes Burks
integrum
ithaca
lepton
luteum
mediopunctatum
modestum
nepotellum
terminatum
pudicum
pulchellum
—
rubromaculatum
rubrum
—
—
terminatum
vicarium
Traver
Carolina
candidum
—
gildersleevei
canadense
ohioense Traver
—
frontale
majus Traver
proximuin Traver(l)
heterotarsale
interpunctatum
affine Traver (2)
conjunction Traver
—
pallidum
femoratum
tripunctatum
birdi Traver
scitulum Traver
annexum
—
bipunctatum
pudicum
exiguum
alabamae Traver(5)
fuscum
rivulicolum (McD.)
integrum
helium Traver
—
—
ithaca
—
luteum
mediopunctatum
Iron modestus
nepotellum
placitum
pudicum
pulchellum
exiguum
rubromaculatum
rubrum
varium Traver
smithae
terminatum
vicarium
Spieth/Others
Carolina
interpunctatum frontale
gildersleevei
interpunctatum canadense
interpunctatum canadense
—
interpunctatum frontale
interpunctatum frontale
interpunctatum frontale
interpunctatum heterotarsale
interpunctatum interpunctatum
interpunctatum interpunctatum
interpunctatum frontale
—
interpunctatum interpunctatum
femoratum femoratum
femoratum tripunctatum
femoratum tripunctatum
femoratum scitulum
integrum(4)
wabasha Daggy (1945)
smithae(6)
(1) Stentmema proximuin is probably the result of hybridization between the subspecies frontale to the east, interpunctatum to the south and
west, and canadense to the north.
(2) Traver described S. affine in 1933 (1933a) and synonymized it with S. heterotarsale in 1935. Spieth (1947) synonymized 5. affine with
5. interpunctatum ss. but Burks (1953) incorrectly considered it a synonym of 5. heterotarsale
(3) Mouthparts and ecology described at length by Dr. Berner (1950)
(4) The nymph described by Leonard and Leonard (1962) as S. integrum is not that species as they suggested. Both the nymph and male
imago that they described are probably S. exiguum, which is common in Michigan
(5) Described ui 1937 from a single male and a few females collected from a store window at Sheffield, Alabama
(6) Berner (1950) described the mouthparts and reported on the ecology of this species.
18
-------
Stenonema annexum Traver
(Figures 96, 110, 175)
Stenonema annexum Traver, 1933: 179; Traver, 1935: 304
NYMPH: Length 10-11 mm.
Head: Reddish brown, lateral areas pale, vertex with large
pale diamond-shaped area; maxilla with 4 or 5 pectinate
spines and 25-30 setae on crown, 20-25 lateral setae; man-
dibles with 6 or 7 teeth on inner margin of each outer
canine (Fig. 96).
Thorax: Reddish brown with small pale spots at base of
wing pads; legs wth 3 irregular dark brown transverse bands
on dorsal surface of femora, claws pectinate near tips (Fig.
110).
Abdomen: Reddish brown dorsally with many minute pale
dots and a dark median stripe extending length of abdomen;
terga 4, 5, and 8-10 dark with irregular pale anterior margins,
tergum 7 pale with median dark line; sterna pale with yel-
lowish-red shading, sometimes with brownish oblique lateral
marks on sternum 9; gills 1-6 truncate at apices, 7th finger-
like gill with a fringe of hairs but without tracheae; postero-
lateral angles of segments 7 to 9 extended as short spines;
caudal filaments pale with brown shading on basal segments.
MALE IMAGO: See Traver (1935) for complete de-
scription.
Genitalia (Fig. 175).
ECOLOGY AND DISTRIBUTION
Very little is known of the ecology of this species. It
has been collected in headwater streams and is probably a
clean-water form.
The known distribution forms a narrow band from eastern
North Carolina southward to Alabama then northward to
southern Indiana (Fig. 189).
Specimens Examined: GEORGIA — Ichawaynochaway
Creek, Morgan, 4IV46, 1 male (Fattig). INDIANA —
Sand Creek, Reddington, 13X65, 1 nymph (Anderson);
White River, Newberry, 14X65, 1 nymph (Anderson).
KENTUCKY —W. Fork Drakes Creek, Franklin, 21V71,
1 male (Myers). NORTH CAROLINA — Fear River,
Buies Creek, 1IV30, 1 nymph (Traver); Goshen Swamp,
11VI29, 1 male (Holotype) (Needham).
DISCUSSION
Traver (1933a) suggested that 5. annexum is near 5. rub-
romaculatum and 5. mediopunctatum; however, the genitalia
are not very similar to either species.
Differences between S. annexum and S. rubrum nymphs
appear to be limited to the amount of dark coloration on
the terga and sterna. There are slight differences in the
male genitalia, and the fore tarsal ratio of S. rubrum is 1.7
compared with 2.0 for 5. annexum. Since I have not reared
either of these species and it is not known if the differences
in genitalia and leg ratio are constant, they are treated here
as separate species.
Stenonema ares Burks
(Figures 69, 95, 115, 129)
Stenonema ares Burks, 1953: 170
NYMPH: Length 10 mm.
Head: Light brown, freckled with numerous white dots,
three large white spots on lateral margin 'near each com-
pound eye; base of antennae dark, remainder white; maxilla
with 2 to 4 pectinate spines but without setae on crown,
15-25 lateral setae (Fig. 69); mandibles with 6 or 7 teeth
on inner margin of each outer canine (Fig. 95).
Thorax: Light brown with many irregular white spots; legs
with basal and median brown band on each tibia, tarsi
brown except base and apex, claws not pectinate (Fig. 115).
Abdomen: Terga 1-5 mostly white, 6-8 mostly brown, 9
brown on meson and near lateral margins, and 10 brown
except for two submedian basal white spots; sterna white
except sternum 9 that sometimes has vague lateral and
basal brown marks; gills 1-6 truncate at apices, 7th finger-
like gill with a fringe of hairs but without tracheae; postero-
lateral angles of segments 7-9 extended as spines; caudal
filaments pale, apical articulations slightly shaded with tan.
MALE IMAGO (Fig. 129): See Burks (1953) for orig-
inal description and figure of genitalia.
ECOLOGY AND DISTRIBUTION
Little is known concerning the ecology of this species.
Nymphs of 5. ares and larvae of the caddisfly, Hydropsyche
orris Ross were collected from the Wabash River from
rubble substrate in moderately swift current. There was
evidence of enriched conditions prevailing in the river (pH
8.0, TDS 330 mg/1) at the time of collection (New Har-
mony, Indiana, 8/14/63). During the following summer,
the mayflies and caddisflies were replaced by bloodworms,
Glyptotendipes sp. (10,000/ft2), indicating that degrading
changes in environmental conditions had eliminated the
S. ares nymphs. However, Leonard (1965) found 5. ares
nymphs in a stream where copper and cyanide concentra-
tions had caused complete fish kills, and Simmons and
Winfield (1971) found that the species was little affected
by siltation.
This species is sympatric with 5. bipunctatiim over most
of Illinois and appears to be common in the Wabash drain-
age system in Indiana (Fig. 189). It is surprising that the
species has not been reported from Wisconsin, because it is
common in the northern counties of Illinois (Burks, 1953).
Specimens Examined: ILLINOIS — Shoal Creek, Green-
ville, 12IV46, 1 male (Paratype) (Mohr and Burks); same
location, 11VI46, 1 nymph (Mohr and Burks); Muddy
Creek, Jewett, 17IV46, 2 nymphs (Mohr and Burks); Rock
River, Rockford, 22V41, 1 male (Ross and Burks). IN-
DIANA— Great Miami River, Lawrenceburg, 15VII71, 1
nymph (Lewis); Wabash River, New Harmony, 14VIII63,
1 nymph (Lewis); same location, 15VII66, 1 nymph (Lewis);
same location 9X166, 1 nymph (Lewis).
DISCUSSION
Adults of this species are easily confused with 5. bipunc-
tatiim. The only reliable character for separating the two
species is the absence of either discal or terminal spines on
the penis lobes of S. ares compared with the penis lobes of
S. bipunctatiim, which are armed with prominent terminal
spines (Fig. 187). Nymphs of S. terminatum and 5. inte-
grum would also key to S. ares in Burks' (1953) key; there-
fore, reports in past literature concerning this species should
be confirmed before using the data.
Stenonema bipunctatum (McDunnough)
(Figures 33, 90, 133, 187)
Ecdyonurus bipunctatus McDunnough, 1926: 191
Stenonema bipunctatum Traver, 1935: 306; Daggy, 1945:
374; Burks, 1953: 169
NYMPH (Fig. 33): Length 10 mm.
Head: Light brown, thickly sprinkled with fine yellow dots,
pale areas around ocelli and lateral to compound eyes; base
of antennae dark brown, remainder paler; maxilla with 2 to
4 spines but without setae on crown, 20-25 lateral setae;
mandibles with 5 or 6 teeth on inner margin of outer canine
(Fig. 90).
19
-------
Thorax: Reddish-brown with a few fine pale dots, pronotum
with three larger pale spots in each anterolateral angle;
legs with two irregular pale bands on femora surrounded
by a thick sprinkling of dark brown freckles, tibiae and tarsi
mostly pale, claws usually pectinate.
Abdomen: Reddish-Brown, thinly sprinkled with pale dots;
terga pale at anterolateral angles, posterior margin of ter-
gum 10 blackish, often paired dark submedian dashes of
adult shows through integument; sterna variable as to
amount of dark coloration, sterna 2-8 usually with paired
submedian, posteriorly divergent dashes, 9 with wide dark
band around outer margin leaving center of sternum pale;
gills 1-6 truncate at apices, 7th gill fingerlike with a fringe
of hairs and without tracheae; posterolateral angles of seg-
ments 4-9 usually extended as spines; caudal filaments
banded with light and dark areas.
MALE IMAGO (Fig. 133): See Burks (1953) or Traver
(1935) for description.
Genitalia with a large terminal spine and small apical spine
on each penis lobe (Fig. 187).
ECOLOGY AND DISTRIBUTION
S. bipunctatum nymphs inhabit unpolluted reaches of
rivers and larger streams. They are usually near, but
seldom found in, swift current. The distribution of this
species is restricted to the Great Lakes Region and Upper
Mississippi Valley in the United States, and extends north-
ward through central Canada (Fig. 190).
Specimens Examined: ILLINOIS — Nippersink Creek,
Spring Grove, 14VI38, 1 female (Burks). NEW YORK —
Niagara Falls, 29VII30, 2 males (Paratypes) (Walley);
Susquehanna River, Binghamton, 5VII69, 1 female (Lewis).
WISCONSIN — Clam River, Burnett Co., 3VI72, 1 male
(reared) (Flowers). CANADA — Assiniboine River, Win-
nipeg, Manitoba, 11VII68, 4 males, 1 female (Flannagan);
Pelee Island, Ontario, 3VII31, 1 male (Walley); Niagara
Falls, Ontario, 28VII25, 1 male (Holotype) (Walley).
DISCUSSION
This species has previously been confused with 5. ares
in both adult and nymph. Previous adult keys were based
on color characters and differences in the ratio of the sec-
ond fore tarsal segment to the first. Examination of the
types has revealed that S. ares lacks discal or terminal
spines on the penis lobes, whereas 5. bipunctatum has large
terminal spines (Fig. 187). Nymphs have not been posi-
tively associated with adults by rearing, but those currently
recognized as this species differ from S. ares in having pec-
tinate claws and posterolateral spines on abdominal seg-
ments 4-9 rather than only on 7-9 as in S. ares. The amount
of variation of these characters infraspecifically is not
known. Since no intergrades have been collected, Burks'
(1953) description-of 5. ares as a new species is considered
sound.
Two nymphs and a reared female imago from the Little
Miami River at Milford, Ohio, are tentatively placed here
until a male is available for comparison with the types. The
female is similar to 5. ares except that the mesonotum is
light clay-colored as in S. bipunctatum rather than reddish-
brown. These two nymphs differ from what is presently
considered to be the nymph of S. bipunctatum in having
5-6 spines and 1-2 setae on the crown of the maxillae and
the tarsal claws are not pectinate.
Stenonema candidum. Traver
(Figures 15, 55, 82, 121, 152, 167)
Stenonema candidum Traver, 1935: 308; Burks, 1953: 162
Stenonema interpitnctatnm frontale Spieth, 1947: 109 (un-
justified synonymy)
NYMPH: Length 8-9 mm.
Head: Light brown, without a pale spot at frontal margin,
triangular white mark near anterior ocellus; maxilla with 7
or 8 pectinate spines but without setae on crown, 15-25
lateral setae (Fig. 55); mandibles with 8 teeth on inner
margin of outer canine of left mandible and 5 or 6 on right
mandible (Fig. 82).
Thorax: Light brown except on median line, a pair of
large sublateral white spots on pronotum; legs brown, each
femur with a basal, median, and apical white crossband,
each tibia white near base and at apex, claws not pectinate.
Abdomen: Light brown; terga with a pair of narrow dis-
continuous submedian white lines (Fig. 15); sterna white,
lateral margin of sternum 8 and lateral and posterior margins
of 9 brown; gills 1-6 pointed at apices, 7th gill fingerlike with
tracheae but without a fringe of hairs; posterolateral angles
of segments 7-9 extended as spines; caudal filaments white
with alternating faint brown articulations.
MALE IMAGO (Fig. 121): See Burks (1953) or Traver
(1935) for complete description.
Genitalia with lateral spines minute or apparently absent
(Fig. 167).
ECOLOGY AND DISTRIBUTION
This species is widely distributed throughout the midwest
but is rare in collections (Fig. 191). Most specimens known
to be this speoies are from springs or cold clear streams.
Bender and Eisele (1971) established a 96-hour TL.0 value
of 2.10 jug/1 for methoxychlor using 5. candidum nymphs as
test animals.
Specimens Examined: ILLINOIS — Belle Smith Spring,
Eddyville, 7VI46, 1 male (Mohr and Burks); Lusk Creek,
Eddyville, 6VI46, 2 males (Mohr and Burks). KENTUCKY
—W. Fork Drakes Creek, Franklin 20V71, 1 male (Myers).
OHIO —Chagrin River, Pleasant Valley, 24VIII33, 1 male,
1 nymph (Paratype) (Traver); same location, 23VH34, 1
female (Allotype) (Traver); Willoughby, 23VI34, 1 male
(Holotype) (Traver).
DISCUSSION
Spieth (1947) synonymized this species with S. interpunc-
tatum frontale, postulating that Traver had either mislabeled
the genitalia of 5. Carolina as this species or that the holo-
type was an aberrant individual. However, neither Burks
nor Edmunds accepted Spieth's synonymy, and an examina-
tion of the holotype and allotype has convinced me that
S. candidum is distinct from S. interpiinctatum. Further-
more, a reared male of this species from Drakes Creek, Ken-
tucky, and a male from Eddyville, Illinois, are similar to
the type, and Daggy collected a male and 5 females from
Minnesota which Traver confirmed as this species. It is
unlikely that the same aberration would occur so regularly
over such a wide area.
Nymphs of 5. candidum differ from S. interpitnctatum
frontale in having 7 or 8 pectinate spines on the crown of
each maxilla compared with 9 for S.i. frontale, the left
mandible has 8 teeth on the inner margin of each outer
canine compared with 6 or 7 for S. i. frontale, and the
abdomen lacks the dark markings on sterna 2-7 so char-
acteristic of 5. /. frontale. The nymph of S. candidum also
lacks a pale spot on the frontal margin of the head which
S. i. frontale nymphs usually possess. Characters used in
20
-------
the nymphal key are based on a slide-mounted exuvia from
Cornell University Museum labeled "paratype" #1342.3.
Male images are easily distinguished by the genitalia
(Fig. 167), which characteristically possess minute lateral
spines. Cross veins in the bulla region are less crowded in
this species than in related species, and they are not con-
nected by a black dash (Fig. 152).
Stenonemu carlsoni Lewis
(Figures 64, 107, 130)
Stenonema carlsoni Lewis, 1974: 347
NYMPH: Length 12-14 mm.
Head: Dark brown, freckled with pale dots, area lateral to
eyes pale; maxilla with 7-9 pectinate spines but without
setae on crown, 25-45 lateral setae (Fig. 64); mandibles
each with 8-10 teeth on inner margin of outer canine (Fig.
107).
Thorax: Dark brown, pronotum with large pale spots near
lateral margins; legs dorsally with 3 irregular dark bands
and three white bands on femora, tibiae pale with basal and
median brown bands, basal half of each tarsus dark, re-
mainder pale, claws not pectinate.
Abdomen: Dorsum pale tan with broken median dark line
on segments 2-8; terga 1, 8, and 9 mostly pale in median
area, terga 2-5 and 7 with large pale submedian areas set
off by brown lateral patches and median dark brown line,
terga 6 and 10 mostly dark brown; sterna pale with faint
dots and bars barely visible in median area of segments 2
to 9, sometimes lateral dark shading near margins of ster-
num 9; gills 1-6 truncate at apices, 7th gill with fringe of
hairs but lacking tracheae; posterolateral angles of segments
3-9 extended as spines; caudal filaments uniformly tan with
ring of stout black setae at articulations.
MALE IMAGO: Length 10-12 mm.
Head: Reddish brown, ocelli black-ringed at bases, usually
a black or purple transverse line across face ventral to
antennal sockets.
Thorax: Dark brown with reddish cast, mesonotum lighter
yellow-brown; mesoscutelhim dark brown; legs yellowish-
tan, wide dark median and apical bands on each femur,
remainder of legs mostly pale tan with dark shading near
joints, fore tarsal ratio 1.5-2.0 (ratio of length of 2nd tarsal
segment to length of 1st); fore wing hyaline with cross veins
crowded in bulla region in first 6-8 interspaces forming a
dark curved streak across wing, reddish brown stain in
stigmatic area in costal and subcostal interspaces, elongated
cells in discal area proximal to bulla region; hind wing with
wide brown band at apical margin (Fig. 130).
Abdomen: Tawny with brownish lateral areas and narrow
black or brown posterior margins on each tergum; genitalia
distinctly boot-shaped, penis lobes with straight apical mar-
gins, apical spines minute, terminal spines large: caudal
filaments yellowish white, articulations brown.
ECOLOGY AND DISTRIBUTION
This species is common in Georgia and South Carolina
where it apparently replaces the closely related S. pudicum
in mountain streams (Fig. 190). Nothing is known of its pol-
lution tolerance but its distribution indicates that a clean
water habitat is preferred.
Specimens Examined: GEORGIA — University Creek,
Athens, 2IV49, 1 female, 1 nymph (Rickert and Scott).
KENTUCKY — Pine Mt. State Park, 18VI58, 1 nymph
(Peters). SOUTH CAROLINA — Eighteen Mile Creek,
Route 56, 1VI66, 1 nymph (Prins); Wildcat Creek, Pickens
Co., 11III67, 1 male (reared) (Carlson).
DISCUSSION
Probably most specimens from South Carolina and Geor-
gia labeled "5. pudicum" are this species, which was recently
described by Lewis (1974). Superficially, they are quite similar
in both nymph and adult. S. carlsoni can be distinguished
from S. pudicum by the following characters: in the nymph,
the crown of the maxilla lacks setae but is armed with 7-9
pectinate spines, whereas S. pudicum has 20-40 crown setae
in addition to the 5-8 pectinate spines; adults lack the dark
sagittate mark in the median area of each tergum so char-
acteristic in 5. pudicum and the dark posterior margin of each
tergum is much narrower than in S. pudicum; there are also
noticeable differences in the arrangement of spines on the
penis lobes.
Stenonema Carolina (Banks)
(Figures 17, 54, 84, 119, 148, 170)
Heptagenia Carolina Banks, 1914: 616
Stenonema Carolina Traver, 1933: 197 (misidentified); 1935:
309; Spieth, 1947: 102; Burks, 1953:
161
NYMPH (Fig. 17): Length 10-12 mm.
Head: Uniform brown; maxilla with 10 heavy pectinate
spines on crown, crown setae absent, 20-30 lateral setae
(Fig. 54); mandibles each with 7 or 8 teeth on inner mar-
gin of outer canine, left mandible with 2 prominent blunt
teeth on inner margin of inner canine (Fig. 84).
Thorax: Uniform brown; legs with femora uniform brown
dorsally, pale below, each tibia with 2 broad pale bands
each side of middle, claws not pectinate.
Abdomen: Almost uniformly brown; terga each with a pair
of short narrow submedian pale streaks at anterior margin;
sterna uniformly light gray-tan without darker markings;
gills 1-6 pointed at apices, 7th gill without fringe of hairs
but with distinct tracheae; posterolateral angles of segments
7-9 extended as spines; caudal filaments gray throughout.
MALE IMAGO (Fig. 119): See Burks (1953) or Spieth
(1947) for description.
Fore \fing with cross veins in bulla region not usually con-
nected by black dash (Fig. 148); genitalia with small apical
and discal spines (Fig. 170).
ECOLOGY AND DISTRIBUTION
Nymphs of S. Carolina inhabit the cold, clear mountain
streams of the Appalachian Mountains from South Carolina
and Georgia to Quebec, Canada (Fig. 191).
Specimens Examined: NORTH CAROLINA — S. Fork,
Swannanoa River, Black Mt., 1 male, 1 female (Paratypes
#1144) (Banks); Catawba River, Swannanoa (Type local-
ity) 18VI30, 1 female (reared) (Traver); Catawba River,
Black Mt., 31V12, 1 male (Beutenmuller); same location,
18VI29, 1 male, 2 females (Traver); Davidson River, Pis-
gah Forest, 20VI26, 1 female (Thompsen); Nolichuky River,
Cranberry, 8V136, 1 female (Traver). SOUTH CARO-
LINA — Keonee River, Clemson, 29IV33, 2 males, 1
female (Dunavan); Reedy River, Greenville, 11X32, 1 male,
1 female (Townes). TENNESSEE — Chimneys Camp-
ground, Smoky Mt. National Park, 24VI39, 3 males; W.
Branch Little Pigeon River, Gatlinburg, 14VIII29, 1 male
(Needham). WEST VIRGINIA — Moores Creek, Warden-
ville, 15VIII30, 1 male, 3 females (Traver). CANADA —
Covey Hill, Quebec, 17VI27, 1 male (Walley).
21
-------
DISCUSSION
Traver's (1933) description of the nymph of this species
was based on misidentified specimens of what she later
described as S. candidum Traver. A male and two females
in the Cornell collection that she collected at Wardensville,
West Virginia, and labeled "S. candidum Traver" appear to
be S. Carolina.
The specimens from Covey Hill, Quebec, have terminal
spines on the penis lobes while those from North Carolina
have discal spines, but in other characters, the two popula-
tions are similar. Probably the Canadian population is suf-
ficiently different to warrant subspecies status.
A female subimago from Sand Creek, Scipio, Indiana,
6V70, and a nymph from Wildcat Creek, Indiana, 5VIII69,
seem to belong to this species, but this needs confirmation
by additional collecting and rearing from these areas.
Stenonema exiguum Traver
(Figures 23, 63, 94, 117, 157)
Stenonema exiguum Traver, 1933: 201; 1935: 310; Daggy,
1945: 374; Berner, 1950: 70
Stenonema alabamae Traver, 1937: 79 NEW SYNONYMY
NYMPH (Fig. 23): Length 9-11 mm.
Head: Brown, heavily sprinkled with fine white dots, pale
area between each compound eye and lateral ocellus, a pale
hat-shaped area anterior to median ocellus, pair of pale
spots lateral to each compound eye divided by a brown
band; basal antennal segments dark brown, flagellum brown
at base, paler distally; maxilla with 4 to 9 pectinate spines
but without setae son crown, 18-25 lateral setae (Fig. 63);
mandibles each with 6-8 teeth on inner margin of outer
canine (Fig. 94).
Thorax: Brown with scattered pale dots, pronotum with
sublateral pale spots near each anterior margin and at
lateral margins, a transverse pale band across mesonotum
at base of wing pads; legs brown sprinkled dorsally with
many dark brown spines, each femur with three irregular
pale bands, tibiae and tarsi largely yellowish, claws pecti-
nate (Fig. 117).
Abdomen: Amount of brown and white (or yellow) quite
variable among specimens; terga 1-3 and 7 largely pale
except in darkest specimens, terga 4 and 5 typically brown
with a pair of submedian and sublateral pale areas (about
evenly brown and white), terga 6 and 8-10 mostly dark
brown, 10 often blackish; sterna almost entirely white or
yellow except segment 9 which has brown posterolateral
angles; gills 1-6 truncate at apices, 7th gill with fringe of
hairs but without a trachea; posterolateral angles of seg-
ments 7-9 extended as spines; caudal filaments alternately
banded with white or yellow and brown.
MALE IMAGO: See Traver (1935) for a complete de-
scription.
Hind wing often with faint brown shading as in Fig. 157;
genitalia with apical and terminal spines of penis lobes
about equal in size.
ECOLOGY AND DISTRIBUTION
Nymphs of this species are seldom found in smaller
streams but occupy the larger creeks and rivers with sandy
bottoms; they live on rocks, logs or other objects anchored
in the sand. Berner (1950) collected a nymph from a
depth of 15 feet in a sand bottomed lake with an Ekman
grab, further substantiating its preference for sandy sub-
strate. Beck (1954) listed S. exiguum as a class I organism,
the presence of which indicates that the water in which
they are found has not been appreciably altered by organic
pollutants. However, Berner (personal correspendence) has
recently collected these nymphs from the shores of a highly
enriched lake in Florida and I have collected them from the
Ohio River in the mesotrophic zone.
This species appears to be abundant in Florida, Alabama,
and Georgia; rare from North Carolina and Tennessee to
Indiana and Illinois; and again becomes abundant in Michi-
gan, Minnesota, and Wisconsin (Fig. 192).
Specimens Examined: ALABAMA — Sheffield, 4VII36,
2 females, 1 male (Types of S. alabamae Traver). GEOR-
GIA — Oostanaula River, Rome, 15VII39, 2 males (Fat-
tig); Etowah River, Rome, 16VIII31, 1 male (Paratype)
(Fattig). INDIANA —Ohio River, Madison, 30VII68, 1
nymph (Lewis.) NORTH CAROLINA—Woodlawn, 16VII30,
1 male (Holotype) (Traver). WISCONSIN—Oconto River,
Oconto Co., 28V69, 1 nymph (Hilsenhoff).
DISCUSSION
This species is quite distinctive in both nymph and adult
and is likely to be confused with only one other species,
5. quinqitespinum, from which it can be separated as discussed
under that species. There are a southern form and a north-
ern form, which are probably subspecies. The southern
form, smaller and paler than the northern form, is very
common in Florida, Alabama, and Georgia. The northern
form is common in Minnesota, Michigan, and Wisconsin.
The nymphs from Michigan that Leonard and Leonard
(1962) tentatively placed as 5. integrum are probably this
species. Nymphs have been collected also from several
scattered locations in the Ohio River Basin, principally from
the Ohio River at Madison, Indiana. The wide gap in dis-
tribution cannot be explained from existing data.
S. alabamae, which is known only from the type series,
differs from S. exiguum only in having the first fore tarsal
segment "fully three-fourths as long as the second." The
range of the fore tarsal ratios in recently examined speci-
mens of S. exiguum from Wisconsin includes the ratios
given for 5. alabamae. The genitalia were missing from the
types and the nymphs are unknown at present.
For the reasons stated above S. alabamae is considered to
be a junior synonym of S. exiguum.
Stenonema femoratum (Say)
(Figures 10, 11, 18, 38, 58, 87, 128, 153, 172)
Baetis femorata Say, 1823: 162
Ecdyonurus femoratus McDunnough, 1925: 190
Stenonema femoratum Traver, 1935: 311; Burks, 1953: 169
Stenonema femoratum femoratum Spieth, 1947: 98
NYMPH (Fig. 18): Length 9-12 mm.
Head: Brown freckled with pale dots, anterior margin with
median indentation (emarginate), never with anteromedian
white spot: maxilla with 2 pectinate spines and 2-16 setae
on crown, 30-40 lateral setae (Fig. 58); mandibles each
with 5-7 teeth on inner margin of outer canine (Fig. 87).
Thorax: Light brown with scattered yellow or white blotches
either side of middle; legs with femora mostly brown with
white spots and covered with dark brown spines, tibiae and
tarsi pale tan, claws pectinate.
Abdomen: Light brown or tan with large pale "X-shaped"
mark extending over terga 7-9 and a smaller "X-shaped"
spot on tergum 5 usually present; sterna 5-8 each pale usu-
ally with a pair of light brown spots near lateral margins,
sterna 1-4 usually pale without darker markings, posterior
half of sternum 9 brown (Fig. 38) (occasionally brown
border is reduced to large brown spots, in which case ter-
gum 9 would have 2 pairs of brown spots, or all ventral
brown spots may be absent); gills 1-6 rounded at apices
22
-------
(Fig. 10), 7th gill with tracheae and fringe of hairs (Fig.
11); posterolateral angles of segments 2-9 produced as large
spines; caudal filaments deep yellow at base, alternating
pairs of segments light and dark in middle and apical areas.
MALE IMAGO (Fig. 128): See Traver (1935) or Burks
(1953) for complete description; Spieth's (1947) descrip-
tion is even more detailed than Traver or Burks.
Fore wing with cross veins crowded in bulla region in first
6 interspaces, dark shading present in bulla region; hind
wing with very wide dark band at apical margin (Fig. 153);
genitalia with apical and discal spines about same size and
shape (Fig. 172).
ECOLOGY AND DISTRIBUTION
Nymphs of S. femoratum are common in small, cool
streams east of the Mississippi River and south of the Great
Lakes to Georgia and South Carolina (Fig. 193). One stream
from which the author collected and reared nymphs received
effluents from a small sewage treatment plant. The mean
yearly TDS for 1969 was 450 mg/1 and the mean TOP was
1.5 mg/1. The mean yearly DO was 9.8 mg/1, and the pH
ranged from 7.5 to 8.0. Gaufin and Tazwell (1952) found
5. femoratum nymphs inhabiting the recovery zone of Lytle
Creek, Ohio, where the DO was often reduced below 2 ppm
at night. This is probably one of the most tolerant may-
flies to organic pollution; in fact, it seems to prefer waters
high in dissolved solids and organic enrichment.
Specimens Examined: ILLINOIS — Herod, 23V46, 1
male (Ross and Mohr); Oakwood, 7V36, 1 male (Ross and
Mohr). INDIANA — Salamonie River, Pennville, 25V66,
1 nymph (Anderson); St. Leon, 23IV69, 3 females (reared)
(Lewis). KENTUCKY — Paint Lick Creek, Kirksville,
15VIII69, 1 nymph (Lewis); Little Kentucky River, Car-
rollton, 13VIII69, 1 nymph (Lewis). OHIO —E. Branch
Chagrin River, Kirtland, 221X32, 1 nymph (Traver); Kain
Run, Williamsburg, 18V71, 1 female (L«wis); same loca-
tion, 27V71, 2 females (reared), 1 male (reared) (Lewis);
same location, 18V71, 2 females (reared) (Lewis); Shayler
Run, Union Township, 2VI70, 1 nymph (Lewis), same
location, 14IV71, 1 male (reared) (Lewis); same location,
23IV71, 1 male (reared) (Lewis).
DISCUSSION
Although Spieth (1947) believed that this species com-
monly intergrades with S. tripunctatum and reduced it to
subspecies, I have found nymphs of both species inhabiting
the same stream pools with little evidence of hybridization.
A total of 24 nymphs from Shayler Run, Ohio, were reared
to adults. Only 3 female imagos reared from S. tripuncta-
tum nymphs showed any S. femoratum characteristics and
these were only minor color characteristics. None of the
S. femoratum nymphs reared out with 5. tripunctatum char-
acteristics. Therefore, S. femoratum, at least in the Ohio
River Basin, is a monotypic species exhibiting very limited
sympatric hybridization.
Stenonema floridense Lewis
(Figure 166)
Stenonema floridense Lewis, 1974: 350
NYMPH: Length 8-10 mm.
Head: Uniform brown anterior to compound eyes and on
vertex, usually small median white spot at anterior margin,
larger white spots lateral to compound eyes; maxilla with 8
or 9 heavy comb-like spines on crown but without crown
setae, 20-25 lateral setae; mandibles each with 7 teeth on
inner margin of outer canine.
Thorax: Uniform brown except for 4 white spots on pro-
notum, 1 near each anterolateral angle, 1 each at anterior
margin midway between meson and lateral margin, a few
small white dots on mesonotum at base of wing pads; legs
brown dorsally each femur with 3 irregular rows of white
spots, these spots much larger on fore legs and middle legs
than on hind legs, venter mostly pale, claws not pectinate.
Abdomen: Mostly brown, an interrupted row of elongated
white spots either side of meson; terga 1-4 and 9 with these
narrow elongate spots nearly continuous as pale lines, ter-
gum 8 with these white spots meeting so that mid-dorsal
area is mostly white, other terga without submedian white
spots, terga 2-7 each with white spots at lateral margins and
midway between lateral margins and meson; sterna 1-8
mostly pale, sternum 9 (and sometimes 8) with lateral
brown bands; gills 1-6 pointed at apices, 7th gill with tra-
cheae but without a fringe of hairs; posterolateral angles of
segments 7-9 extended as spines; caudal filaments very light
brown.
MALE IMAGO: Length 7-9 mm.
Head: Pale yellowish white, ocelli black ringed at bases,
typically face below antennal sockets is without black mark-
ings, but faint black dots, dashes or an unbroken line may
be present; reddish-brown shading and gray dots on vertex.
Thorax: Light yellow-brown, two black streaks on prono-
tum; mesoscutellum white; legs greenish-yellow or white,
faint reddish-brown median and apical bands on femora,
median band usually missing from hind femur, apex of
tibia brown, fore tarsal ratio 2.0-2.4; fore wing hyaline,
dark dash at bulla sometimes connecting 2 or more cross
veins, sometimes this dash reduced to small dot; hind wing
with dark apical margin.
Abdomen: Hyaline with narrow black line at posterior
margin of each tergum, no spiracular dots, alabaster white
pigment on dorsum of segments 8 and 9; genitalia (Fig.
166) with large lateral spines and 2 to 4 large curved axial
spines that may be three-lobed, apical spine minute or ap-
parently lacking, discal spine as in S. interpunctatum; caudal
filaments light gray throughout.
ECOLOGY AND DISTRIBUTION
This species is common in the panhandle of Florida and
is the only species of the INTERPUNCTATUM group
found in the sandy bottomed Blackwater River Basin of
Santa Rosa and Okaloosa Counties. The streams in this
basin are relatively swift and keep the shifting sand in
almost constant motion. Most of the normal flow is ground
water which is extremely soft, slightly mineralized, and low
in dissolved nutrients. Beck (1973) reported pH ranges
from 5.0-6.3, TDS ranges from 15-17, and DO ranges from
6.8-9.7.
Probably S. floridense is restricted to the naturally acid
streams of the southeast that have not been effected by
pollution (Fig. 190).
Specimens Examined: FLORIDA — Blackwater River,
Blackman, 1V70, 1 male, 4 females (Allotype) (Peters);
same location, 27IV72, 1 nymph (Peters); Blackwater River,
Holts, 21IV72, 4 males (Holotype and Paratypes) (Peters);
same location, 9IV71, 1 male (Paratype) (Peters); same
location, 17VI71, 1 nymph (Peters); same location, 28IV72,
2 males, 1 female (Paratypes) (Peters), same location
8V71, 2 males (Peters); same location, 21IV68, 1 male
(Beck); Comfort Creek, Quincy, 16IV67, 1 male (Peters);
Chipola River, Calhoon Co., 12IV72, 1 male (Carlson);
Holmes Creek, Brock Crossroad, 23IV67, 1 male (Peters);
Rocky Comfort Creek, Gadsden Co., 1 male (Paratype)
(Jones).
23
-------
DISCUSSION
This species superficially resembles S. interpunctatum in
both adult and nymph; however, the armature of the male
genitalia is distinctly different from that of any related
species (Fig. 166). None of the specimens examined showed
any trace of black pleural streaks or black spiracular spots;
otherwise color characters vary considerably as in S. inter-
punctatum.
Nymphs can usually be separated from S. interpunctatum
by the presence of 8 pectinate spines on the crown of the
maxilla. Nymphs, which occasionally have 9 spines on the
crown of each maxilla as in many S. interpunctatum, are
separated by the following combination of characters: 7
teeth on inner margin of outer canine, 4 teeth on inner
margin of inner canine, less than 25 lateral setae on maxilla,
and dorsal color pattern of interrupted elongate pale spots.
Stenonema fuscum (Clemens)
(Figures 29, 46, 75, 101, 132, 147, 184)
Heptagenia fusca Clemens, 1913: 254
Ecdyonurus fuscus McDunnough, 1933: 35 (redescription)
Stenonema fuscum Traver, 1935: 314; Burks, 1953: 173
Stenonema rivulicolum McDunnough, 1933: 40; Traver,
1935: 328 NEW COMBINATION
NYMPH (Fig. 29): Length 10-12 mm.
Head: Mostly brown with freckles of pale dots, pale spots
at posterior margin and lateral to compound eyes; maxilla
with 2-4 pectinate spines and 10-40 setae on crown, 25-35
lateral setae (Fig. 75); mandibles each with 7 or 8 teeth
on inner margin of outer canine (Fig. 101).
Thorax: Mostly brown with pale spots near anterior and
lateral margins of prothorax; legs brown dorsally with 3
irregular pale bands across each femur, mostly pale ven-
trally, claws not pectinate.
Abdomen: Mostly dark brown, terga darkest at posterior
margins, sterna 1-8 each with a broad, transverse crossband
at posterior margin, sternum 9 with a large brown spot at
each posterolateral angle (Fig. 46); gills 1-6 truncate at
apices; 7th gill with fringe of hairs but without tracheae;
posterolateral angles of segments 3-9 extended as spines;
caudal filaments uniformly tan in basal area, alternating
pairs of segments dark and light distally.
MALE IMAGO (Fig. 147): See Traver (1935) for com-
plete description. Burks' (1953) description is adequate,
except that the genitalia of this species is shown in his
figure 344 rather than his figure 346 which is the genitalia
of S. vicarium.
Genitalia of the holotype are shown in Fig. 184.
ECOLOGY AND DISTRIBUTION
S. fuscum seems to be rare in the Ohio River Basin, it
becomes more common north and west of the Great Lakes
(Fig. 194). Nymphs inhabit riffle areas in rivers and larger
streams.
Specimens Examined: MICHIGAN — Boardman River,
Kalkaska Co., 18III71, 1 nymph (Meier); Little Manistee
River, Irons, 28V39, 1 nymph (Burks); Platte River, Honor,
27V39, 2 males (Prison and Ross); Rapid River, Kalkaska
Co., 18III71, 1 nymph (Meier). MINNESOTA — Baptism
River, Finland, 29X64, 1 nymph (Bell); Devil Track River,
Gunflint Trail, Cook Co., 3IV65, 1 nymph (Lemke); Split-
rock River, Hyway 3, Lake Co., 29X64, 1 nymph (Bell).
WISCONSIN —St. Croix River, Dairyland, 24V67, 1 male
(reared) (Nebeker and Bell); St. Croix River, Gordon,
30III67, 4 nymphs (Lemke and Mattson); Otter Creek,
Sauk Co., 23IV72, 1 male (reared) (Flowers); Averill
Creek, Lincoln Co., 25V72, 1 male (reared) (Flowers).
PENNSYLVANIA — S. Branch Oswego Creek, Coneville,
24VII69, 1 male (Lewis). CANADA —Scott Creek, Rid-
ing Mt. Nat. Park, Manitoba, 20VI68, 1 nymph (Flanna-
gan); Fairy Lake, Quebec, 30V27, 1 male (Holotype of
S. rivulicolum) (Walley). Sandy Grey Falls, Go-Home
River, Ontario, 23VI12, 1 male (Holotype) (Clemens);
Renous River, Renous, New Brunswick, 181X69, 1 nymph
(Ulrich).
DISCUSSION
There has been some doubt as to whether S. vicarium and
S. fuscum are valid species. Koss (1968) was not able to
find any differences in the eggs of the two. Walton, Uni-
versity of Wisconsin (personal communication), collected a
large number of nymphs of these two species from streams
in Wisconsin. These nymphs could be arranged in a series
starting with specimens that were typical of S. vicarium and
progressing through intergradations to specimens typical of
S. fuscum. I have seen this display and admit that it looks
very convincing. Walton did not rear any nymphs, and I
suspect that those he called S. vicarium were in reality S.
rivulicolum, which I would expect to hybridize with S.
fuscum. There is little doubt that S. rivulicolum (Fig. 132)
is intermediate between S. fuscum and S. vicarium, as Traver
(1933) noted. Burks (1953) synonymixed S. rivulicolum
with S. vicarium probably as a result of the reversed figures
of the genitalia as mentioned above. The genitalia of the
holotype of S. rivulicolum is definitely similar to the holotype
of S. fuscum, and therefore, S. rivulicolum becomes a syno-
nym of S. fuscum.
Although the nymphs of S. vicarium and 5. fuscum can
be separated only on the amount of dark coloration on the
ninth sternum, there are good morphological characters for
separating the adults based on wing veination and arrange-
ment of spines on the genitalia.
Stenonema gildersleevei Traver
(Figures 8, 9, 16, 59, 81, 168)
Stenonema gildersleevei Traver, 1935: 315; Spieth, 1947:
103; Burks, 1953: 163
NYMPH: Length 9-11 mm.
Head: Mostly brown, areas lateral to compound eyes pale,
pale areas near posterior margin; maxilla with 11-13 heavy
pectinate spines on crown but without crown setae, 30-40
lateral setae (Fig. 59); mandibles each with 7-9 teeth on
inner margin of outer canine, 3-7 teeth on inner margin of
inner canine (Fig. 81).
Thorax: Mostly pale brown with a pair of large black spots
on pronotum and several smaller black spots near wing
bases; legs brown dorsally with scattered pale areas, ventral
surfaces white; claws not pectinate.
Abdomen: Color pattern consists of elongate pale spots
on dark brown background (Fig. 16); terga with black
crossbands at posterior margins thus separating each elon-
gate pale spot so that they do not form the pale submedian
bands so characteristic of most nymphs of the INTER-
PUNCTATUM group; sterna white, faint longitudinal
dashes at lateral margins of segments 7-9 often present;
gills 1-6 pointed at apices (Fig. 8), fingerlike 7th gill with
a single trachea but without a fringe of hairs (Fig. 9);
posterolateral angles of segments 7-9 extended as spines;
caudal filaments yellow throughout.
MALE IMAGO: See either Traver (1935), Spieth (1947),
or Burks (1953) for a complete description.
Genitalia lacking apical spines but a terminal spine is pres-
ent on each penis lobe (Fig. 168).
24
-------
ECOLOGY AND DISTRIBUTION
This species seems to prefer cold, spring-fed streams. The
type series examined was reared from nymphs taken from
a spring-fed stream in northern Ohio. Four female imagos
from near Hitchcock Creek, Pennsylvania, and a nymph
from Laurel Brook, Tennessee, probably were inhabitants
of extremely cold spring-fed streams (Fig. 195).
Specimens Examined: OHIO — Chagrin River Tributary,
Kirtland, 22VIII30, 1 male (reared) (Paratype), 3 nymphs
(Traver); same location, 31VIII29, 1 nymph (Traver);
same location, 71X32, 1 female (reared) (Paratype)
(Traver); same location, 25VIII30, 1 female (reared)
(Paratype) (Traver); same location, 6VIII32, 1 female
(reared) (Paratype) (Traver); same location, 221X32, 1
nymph (Traver); same location, 141X30, 1 nymph (Traver);
same location, 10VIII32, 1 nyniph, 1 female (Paratype)
(Traver). PENNSYLVANIA — Hitchcock Creek, Cherry
Grove, 22VIII69, 4 females (Lewis). TENNESSEE—Laurel
Brook, Walden Ridge, Rhea Co., 231X69, 1 nymph (Lewis).
DISCUSSION
Adults of this species are often confused with S. inter-
punctatum canadense differing only in their larger size and
in having a black longitudinal line on each sternum.
Nymphs are separated from other closely related species,
except S. pallidum, by the number of spines on the crown
of the maxillae (11-13) and from S. pallidum by the num-
ber of lateral setae (30-45) and dorsal color pattern (Fig.
16).
Stenonema integrant (McDunnough)
(Figures 25, 37, 70, 97, 134, 139, 140, 160, 177)
Heptagenia integer McDunnough, 1924: 9
Stenonema integrum Traver, 1935: 317; Burks, 1953: 176
Stenonema metriotes Burks, 1953: 174 NEW SYNONYMY
NYMPH (Fig. 25): Length 7-8 mm.
Head: Dark brown, sprinkled with pale dots, a small me-
dium spot and 2 larger lateral spots on anterior margin,
lateral margins pale with brown band connecting each eye
with lateral margin; pale areas near each ocellus; maxilla
with 2 or 3 pectinate spines and 30-50 setae on crown;
15-25 lateral setae (Fig. 70); mandibles with 5-8 teeth on
inner margin of outer canine (Fig. 97).
Thorax: Brown, a cuneiform-shaped pale streak begins
near posterior margin of head, widens across pronotum, and
tapers off near middle of mesonotum; legs mostly pale,
each femur with 3 irregular transverse brown bands, tibiae
with brown bands basally and near middle, basal half of
tarsi brown, claws usually not pectinate.
Abdomen: Dark brown; terga 2-7 with pale submedian
streaks on anterior portions, middle of tergum 1 mostly
pale; a conspicuous pale "V-shaped" median patch with
vertex on tergum 9 or 10 extends across terga 7 and 8;
terga 4 and 5 often with pale submedian patches; pale
lateral streak on terga 2-8 usually concealed under gills;
sterna usually entirely pale except for sternum 9, which
often has lateral dark bands that may coalesce anteriorly
to form a dark inverted U-shaped mark (Fig. 37); gills 1-6
truncate at apices, fingerlike 7th gill with a fringe of hairs
but no tracheae; posterolateral angles of segments 7-9 pro-
duced as spines; caudal filaments pale basally, ringed with
brown beyond the middle with an alternating pattern of 3
brown segments separated by 1 pale segment.
MALE IMAGO (Fig. 139): Length 5-7 mm.
Head: Chalky white, vertex stained with pale yellow.
Thorax: Pronotum pale yellow; mesonotum and metanotum
chalky white; pleura and vertex of thorax chalky white;
mesoscutellum all white; legs yellowish white, each femur
with prominant red-brown crossband near middle and at
apex, fore tarsal ratio 1.5-2.0; fore wing hyaline, stigmatic
area stained with brown, cross veins slightly crowed in
bulla region, the cross veins in bulla region and beyond
forming irregular lines across wing setting off elongate cells
distal to bulla region (Fig. 160); hind wing usually with
narrow brown apical margin.
Abdomen: White; terga 1-9 each with a narrow black
cross band at posterior margin, those on terga 2-6 often
reduced to a minute black median dash (Fig. 134), the
narrow band on terga 7-9 often interrupted on the meson;
a longitudinal dark gray line on meson of terga 3 and 6
(Fig. 140); spiracular marks, if present, a series of oblique
dark brown streaks (Fig. 139); genitalia with discal spines
on penis lobes (Fig. 177); caudal filaments white, joinings
narrowly dark brown.
ECOLOGY AND DISTRIBUTION
S. integrum is distributed throughout most of the United
States (Fig. 194). The nymphs are tolerant to a wide range
of conditions and have been found in the Ohio River where
pollution (both organic and toxic) had eliminated all the
more intolerant mayfly species. Any permanent stream may
harbor a few individuals, but the nymphs of this species seem
to prefer large, deep rivers such as the Ohio and Mississippi,
where they are especially abundant below sewage outfalls.
Specimens Examined: ARKANSAS — Arkansas River,
Little Rock, 6VI68, 1 nymph (Woomer); Cove Creek,
Washington Co., 6VI62, 1 male (Peters). FLORIDA —
Blackwater River, Okaloosa Co., 1VI70, 5 males (Peters).
ILLINOIS — Mississippi River, Poplar Bluff, 20VI43, 1
male (Prison); Alton, 27VIII13, 2 males (Paratypes) (Mc-
Dunnough); Ohio River, Cairo, 221X67, 1 nymph (Ander-
son). INDIANA — Great Miami River, Lawrenceburg,
23VII68, 1 nymph (Lewis); Ohio River, Madison, 14VII69,
3 nymphs (Lewis); Ohio River, Evansville, 51X67, 1 nymph
(Anderson); Wabash River, New Harmony, 15V63, 1
nymph (Anderson); same location, 15VII66, 1 nymph
(Anderson); White River, Newberry, 14X65, 1 nymph
(Anderson). KANSAS — Kansas River, Lawrence, 241X59,
1 male (Peters). KENTUCKY — Ohio River, Louisville,
6VII66, 1 nymph (Mason); Ohio River, Warsaw, 17VI68,
1 nymph (Lewis). MAINE — Crooked River, Harrison,
14VII71, 1 female (Lewis). MINNESOTA — Mississippi
River, Wabash, 7VII40, 1 female (reared), 1 male (Para-
types of S.wabasha) (Daggy); Mississippi River, Winona,
9VII37, 1 male (Paratype of S. wabasha) (Daggy); same
location, 5VII37, 1 female (Daggy). NORTH CARO-
LINA— French Broad River, Penrose, 19VII30, 1 male
(Holotype of S. helium) (Traver). OHIO — Little Miami
River, Loveland, 20X68, 1 female (reared); Little Miami
River, Cincinnati, 8X68, 1 nymph (Lewis); Ohio River,
Cincinnati, 2X68, 8 nymphs (Lewis); same location,
26VHI69, 1 male, 5 females (reared) (Lewis); same loca-
tion, 51X67, 3 nymphs (Lewis); same location, 22VIII70,
10 males (reared), 15 females (reared), 3 nymphs (Lewis);
Ohio River, Portsmouth, 121X68, 2 nymphs (Lewis); Ohio
River, Miami Fort, 101X68, 1 nymph (Lewis); Scioto
River, Portsmouth, 111X68, 1 nymph (Lewis). PENN-
SYLVANIA—Ohio River, Emsworth Dam, 16VI70, 1
nymph (Fullner). SOUTH CAROLINA — Clemson Col-
lege, 26VI35, 1 female (Traver).
DISCUSSION
Much of the confusion that existed in this complex was
cleared up by Burks (1953) when he synonymized S. wa-
25
-------
basha Daggy and S. helium Traver with S. integrum. The
group is further simplified in this manual by synonymizing
5. metriotes Burks with 5. integrum.
When Burks (1953) first described S. metriotes he sug-
gested that it "may eventually prove to be only a variant
of integrum." I have examined the type series and must
agree that they look distinct from S. integrum, and it leads
me to wonder why Burks had reservations about the status
of the species. However, during rearing of 41 nymphs of
S. integrum from the Ohio River, images of S. metriotes
consistently turned up in the tanks even though there was
no visible difference in the nymphs. Eleven of the 16 5.
metriotes were males and 19 of the 25 S. integrum were
females. Apparently 5. metriotes is a variant of S. integrum,
usually a male, in which the black coloration is considerably
reduced so that the spiracular dots are absent and the dark
lines at the posterior margins of the abdominal terga are
reduced to short, median dashes (Fig. 134). Several speci-
mens showed intermediate characters.
Descriptions and photographs of both nymphs and adults
of S. integrum appearing in this manual were taken from
Ohio River specimens; however, reared males from the
Ohio River nymphs were compared with McDunnough's
holotype and found to be similar. The nymph originally
described by Daggy (1945) as S. wabasha and later synony-
mized with S. integrum by Burks (1953) differs from these
Ohio River nymphs in having only 5 or 6 teeth on the inner
margin of the outer canine of each mandible and pectinate
claws. Adults of S. wabasha lack the narrow dark apical
margins on the hind wings, the fore wings lack elongate
cells as characteristic of the Ohio River specimens, and
there are slight differences in the genitalia. I consider the
specimens from Minnesota and Wisconsin to be subspecies
S. integrum wabasha.
Stenonema interpunctatum (Say)
(Figures 14, 35, 36, 56, 85, 86, 122, 123,
124, 125, 126, 149, 150, 169)
Baetis interpunctata Say, 1839: 14
Stenonema interpunctatum interpunctatum Spieth, 1947: 106
Stenonema interpunctatum canadense Spieth, 1947: 107
Stenonema interpunctatum frontale Spieth, 1947: 109
Stenonema interpunctatum heterotarsale Spieth, 1947: 110
Stenonema interpunctatum Traver, 1935: 317; Spieth, 1947:
104; Burks, 1953: 166
Stenonema areion Burks 1953: 163 NEW SYNONYMY
NYMPH: Length 8-11 mm.
Head: Anterior to compound eyes uniform brown; pale
spots on margins lateral to compound eyes and near each
ocellus, sometimes with light spots on anterior margin;
maxilla with 8-10 heavy pectinate spines and no setae on
crown, 20-30 lateral setae (Fig. 56); mandibles each with
5-7 teeth on inner margin of outer canine, inner canine
with 2-4 blunt teeth on inner margin (Figs. 85 and 86).
Thorax: Mostly uniform brown, pronotum with a pair of
sublateral and a pair of anterolateral pale spots; legs light
brown dorsally, femora with pale spots forming 3 irregular
bands across dorsal surface, pale ventrally, claws not pec-
tinate.
Abdomen: Ground color brown; terga 1-9 with 1 or 2
pairs of nearly continuous longitudinal pale streaks length
of abdomen (Fig. 14); sterna mostly white, often with dark
shading in lateral areas (Figs. 35 and 36); gills 1-6 pointed
at apices, 7th gill with tracheae but without fringe of hairs;
posterolateral angles of segments 7-9 extended as spines;
caudal filaments light brown usually with articulations al-
ternating light and dark in apical third.
MALE IMAGO (Figs. 124 and 126): Length 8-10 mm.
Head: Yellow or white often tinged with green, black dot,
dash, or line usually present on clypeus under antennal
sockets (Fig. 125), vertex usually reddish brown.
Thorax: Pronotum white usually with oblique black streak
on each side, remainder of thorax brown dorsally; meso-
scutellum yellow with brown tip; legs yellow, each femur
with dark brown crossbands at apex and near middle, hind
femur often lacks median crossband, tibiae black at apices,
fore tarsal ratio 1.1-3.5; fore wing hyaline, stigmatic area
stained with brown, usually 2 or more cross veins in radial
space in bulla region connected with black dash (Fig. 150);
hind wing with brown apical margin (Fig. 149).
Abdomen: Yellow or white, sometimes with dark shading
on meson (Fig. 123), apical 3 terga shaded with pink,
orange, or brown, posterior margin of each tergum with
narrow black crossband (Fig. 122), spiracular black marks
present in some subspecies, absent in others; genitalia with
apical spines either very small or apparently lacking (Fig.
169).
ECOLOGY AND DISTRIBUTION
Nymphs of Stenonema interpunctatum are common in
almost any unpolluted stream east of the Rocky Mountains,
and at least one subspecies is apparently able to tolerate
considerable organic enrichment (Gaufin, 1958). I have
collected the nymphs from a stream in southern Ohio that
received moderate amounts of organic pollutants from an
overloaded sewage treatment plant; however, the current
was swift and the DO was near saturation. In the Ohio
River downstream from Cincinnati where the DO often
falls below 4.0 ppm during the summer, the nymphs of 5.
interpunctatum are generally scarce, whereas they are abun-
dant in the unaffected reaches upstream of the city.
The presently recognized subspecies are distributed as fol-
lows (Fig. 196): Stenonema interpunctatum canadense
(Walker) sensu Spieth is a dark, northern form of the species
inhabiting lakes and pools of clean water streams of eastern
Canada and the northern tier of the eastern and midwestern
States, and extending southward along the eastern highlands
to NorthCarolina. Stenonema interpunctatum frontale (Burks)
sensu Spieth is an eastern subspecies inhabiting clean water
streams from Lake Erie to the Atlantic Seaboard. Stenonema
interpunctatum interpunctatum (Say) sensu Spieth is com-
mon and widespread in small streams and rivers in the
lower and middle Mississippi and in the Ohio River drain-
ages. Nymphs were common in rocky-bottomed streams
where pH ranged from 6.7-8.2, the TDS ranged from 98-
700 mg/1, the TOP ranged from 0.0-10.0 mg/1, and DO
ranged from 4.0-14.0 mg/1. The form designated 5. affine
Traver is common in streams of the southeastern States.
The distribution of Stenonema interpunctatum heterotarsale
(McDunnough) sensu Spieth is centered around Lake Erie
and Lake Ontario and extends westward into northern In-
diana and Illinois and southward to central Ohio.
Specimens Examined: Stenonema interpunctatum inter-
punctatum: FLORIDA — Chipola River, Calhoun Co.,
20IV72, 2 males (Carlson); same location, 12IV72, 1 male
(Carlson). ILLINOIS —Fox River, St. Charles, 9VI48,
1 male (Burks); Muddy River, Benton, 10VI46, 1 male
(Ross); Vermilion River, Oakwood, 6VI25, 1 nymph (Pri-
son). INDIANA —Big Blue River, Shelbyville, 4VIII69,
1 nymph (Lewis); Wabash River, Wabash, 5VIII69, 1
nymph (Lewis); Wildcat Creek, Prymont, 4VIII69, 3 fe-
males, 1 nymph (Lewis); Wildcat Creek, Rossville, 4VIII69,
1 female, 1 nymph (Lewis); Wildcat Creek, Jerome,
5VIII69, 1 nymph (Lewis). KANSAS—Lawrence, 16VII32,
26
-------
1 male (Brown). KENTUCKY — Kentucky River, Wil-
more, 15VIII69, 1 nymph (Lewis); W. Fork Drakes Creek,
Franklin, 1V71, 1 male (Myers). NORTH CAROLINA —
Caraway Creek, Sophia 23IV30, 1 male (Holotype of S.
affine) (Traver). OHIO —Chagrin River, Willoughby,
17VIII32, 1 male (Holotype of S. conjunctum) (Traver);
Ohio River, Cincinnati, 22VIII70, 2 nymphs (Lewis); Shay-
ler Run, Union Township, 23IV71, 3 males (reared), 1
female subimago, 1 nymph (Lewis); same location, 28V69,
2 males, 1 female, 2 nymphs (Mason); same location
13VI69, 2 nymphs, 2 females (Lewis); Stillwater River,
Pikeville, 171X69, 1 nymph (Lewis); White Lake, Waverly,
4VI69, 1 nymph (Lewis). OKLAHOMA — Blue River,
Reagan, 1V39, 1 male (Ross). WEST VIRGINIA —Po-
tomac River, Smoke Hole, 7VIII30, 1 nymph (Paratype of
S. affine) Traver.
Stenonema interpunctatum canadense: ILLINOIS — Oak-
wood, 25VI48, 2 males (Paratypes of S. areion) (Burks).
INDIANA —Wildcat Creek, Prymont, 4VIII69, 1 female,
1 nymph (Lewis). MAINE — Crooked River, Harrison,
17VII71, 2 females (reared) (Lewis). MICHIGAN —
Davis Creek, Silver Lake, 18III71, 1 nymph (Meier). NEW
YORK — Susquehanna River, Binghamton, 18VIII68, 1
nymph (Lewis). PENNSYLVANIA — Hitchcock Creek,
Cherry Grove, 22VII69, 3 females (Lewis); S. Fork Os-
wego Creek, Coneville, 24VII69, 1 female, 1 nymph (Lewis).
OHIO —Paine Creek, Leroy, 7VIII33, 2 males, 2 females
(Paratypes of S. ohioense) (Traver); Chagrin River, Pleas-
ant Valley, 25VIII30, 1 female (reared) (Traver); same
location, 31VIII29, 1 male (subimago) (Traver); same
location, 141X30, 1 nymph (Traver). CANADA — Willow
Creek, 40 mi. w. of Winnipeg, Manitoba, 7VIII68, 2 males
(reared) (Flannagan); Britannia, Ontario, 14VI22, 1 male,
1 female (McDunnough).
Stenonema interpunctatum frontale: MAINE — Carsley
Brook, Harrison, 12VII71, 1 male (reared), 1 nymph
(Lewis). MASSACHUSETTS — Middlesex Falls, no date,
1 male (Holotype) (Banks). NEW YORK — Cranberry
Lake, 26VI20, 1 female (Drake); Cascidilla Creek, Ithaca,
16VII32, 1 male (Holotype of S. majus) (Traver); White
Church (Ithaca) 12VI33, 2 males, 1 female (Holotype and
Paratypes of S. proximum) (Traver); Wilseyville Creek,
Ithaca, 10VI33, 2 males (Paratypes of 5. proximum) (Green-
wald). CANADA — Little S. W. Miramichi River, New
Brunswick, 141X69, 1 nymph (Ulrich); Ottawa Golf Club,
Quebec, 21VII24, 1 male (Homotype) (Ide).
Stenonema interpunctatum heterotarsale: ILLINOIS —
Little Wabash River, Crossville, 6VIII69, 1 male, 1 female
(subimagos) (Lewis); Vermilion River, Oakwood, 6VI25,
1 nymph (Prison). OHIO — Little Miami River, Cincin-
nati, 18VII68, 1 male (Lewis); Mohican River, Danville,
23VI69, 2 females (reared), 1 nymph (Lewis); CANADA
— Ottawa, Ontario, 19VI24, 1 male (Paratype) (Ide):
same location, 13VI27, 1 male (McDunnough).
DISCUSSION
Both nymphs and images are very similar to S. minne-
tonka, S. floridense, and S. pallidum, differing primarily in
the arrangement of spines on the male genitalia and the
number of spines on the crown of the maxillae of the
nymphs. See the discussion under those species for descrip-
tions of characters used to separate the four species and
Spieth (1947) for descriptions of the four subspecies.
The S. interpunctatum complex is, at present, only super-
ficially known,; therefore, the foregoing diagnosis must be
considered tentative until confirmed by careful rearing of
nymphs from many localities to help us understand the dis-
tribution patterns of the several subspecies (or species). All
the different populations must be segregated out and areas
of hybridization pinpointed. Studies should be designed to
ascertain whether the apparent hybrids are truly hybrids or
are environmental variants within species. The influence of
glaciation and biogeography on the distribution of the sev-
eral populations needs investigation. Are the apparent sub-
species the result of glacial segregation? If so, are they now
intermingling over their entire ranges?
Spieth (1947) recognized 4 subspecies of S. interpuncta-
tum (heterotarsale, interpunctatum, frontale, and canadense),
based on first fore tarsal ratio and fore wing length of the
males, and synonymized 6 other species under 5. interpuncta-
tum (see Table 2). The nymph of subspecies S. heterotarsale
has not as yet been positively associated with the adult by
rearing, and the differences between the nymphs of subspecies
canadense, frontale, and interpunctatum are so minor that it
is not wise at this time to attempt to separate them without
the associated images.
Although the images of these subspecies have definite
color patterns, they cannot be recognized as distinct species
because of obvious hybridization and similarities in geni-
talia. S. interpunctatum frontale hybridizes with S. inter-
punctatum canadense in central and western New York,
southern Ontario, northern Ohio, and western Pennsylvania,
and with 5. interpunctatum interpunctatum in southern New
York, Ohio, and Kentucky. Hybrids resulting from crosses
between S. interpunctatum heterotarsale and S. interpuncta-
tum canadense were examined from eastern Illinois, south-
ern Ontario, and southern Michigan. 5. interpunctatum
heterotarsale hybridizes with S. interpunctatum s.s. in north-
central Indiana. Hybrids of S. interpunctatum interpuncta-
tum and S. interpunctatum canadense appear to be common
in all the midwestern States north of the Ohio River.
The type specimens of 5. areion Burks (Fig. 122) from
Illinois appear to be hybrids between S. interpunctatum
heterotarsale and S. interpunctatum canadense. The lack of
dark spiracular dots and dark facial marks may be attribut-
able to S. heterotarsale, but the genitalia are distinctly sim-
ilar to that of S. interpunctatum canadense. Posterior mar-
gins of the terga of the holotype and paratypes have dark
brown bands, rather than a "mars orange crossband" as
stated by Burks (1953). It is possible that the color changed
upon drying, but other specimens from near the "type
locality" had the characteristic dark brown crossband. The
fore tarsal ratio for 5 specimens of S. areion ranged from
2.1-2.6, which is well within the range for S. interpunctatum
canadense. Two of these specimens had dark pleural streaks,
and one had the dark spiracular dots characteristic of S. inter-
punctatum canadense. None of these Illinois specimens pos-
sessed the dark median longitudinal band on the terga (Fig.
123) so characteristic of S. interpunctatum canadense from
Canada. The genitalia of all five specimens were similar to
those of S. canadense from Ontario and Illinois. For these
reasons S. areion is reduced to a junior synonymy of 5.
interpunctatum canadense, accepting in principle Spieth's
(1947) diagnosis of the group. See Table 2 for subspecies
and synonyms.
Stenonema ithaca (Clemens and Leonard)
(Figures 27, 41, 67, 93, 131, 161, 182)
Heptagenia ithaca Clemens and Leonard, 1924: 17
Stenonema ithaca Traver, 1935: 318; Burks, 1953: 173
NYMPH: Length 10-11 mm.
Head: Light brown speckled with small pale dots, a pale
oblique band extending from anterolateral angle of each
compound eye to lateral margins; maxilla with 4-6 pectinate
spines but without setae on crown, 15-25 lateral setae (Fig.
27
-------
67); mandibles each with 6-7 teeth on inner margin of outer
canine (Fig. 93).
Thorax: Mostly brown; legs pale with 2 broad light brown
bands across each femur, claws not pectinate.
Abdomen: Light brown ground color; terga with a few pale
blotches and small dots (Fig. 27); sterna 4-8 white with
brown angulated transverse bars across middle (Fig. 41),
sternum 9 with pair of oblique brown bands sometimes
meeting on meson at anterior margin to form an inverted
"V"; gills 1-6 truncate at apices, 7th gill with fringe of
hairs but without tracheae; posterolateral angles of seg-
ments 7-9 extended as spines; caudal filaments uniformly
yellow, sometimes with alternating dark and light segments
near tip.
MALE IMAGO: Length 9-10 mm.
Head: Dark red-brown, face below antennal sockets usu-
ally with a narrow black line across face, antennae brown
at base becoming hyaline near tips.
Thorax: Dark red-brown on nota, pleura mostly yellow-
brown with darker shading at wing bases; mesoscutellum
dark red-brown; legs yellow with reddish shading except
fore femora, which are light reddish-brown, each femur
with a median and apical purple band, fore tarsal ratio
2.0-2.3; fore wing hyaline with numerous cross veins form-
ing short cells, cross veins in bulla region slightly crowded,
usually 1 cross vein in costal space and 2 or 3 in each of
the 2 following spaces (Fig. 161), stigmatic area washed
with yellow-brown; hind wing hyaline without dark apical
margin.
Abdomen: Mostly dark brown; terga 1-7 slightly lighter
at anterior margins, stigmal dots obscured by dark brown
shading (Fig. 131); genitalia with minute apical spine and
small subterminal spine on each penis lobe (Fig. 182);
caudal filaments yellow with dark joints.
ECOLOGY AND DISTRIBUTION
Nymphs of S. ithaca prefer the gentle riffles of small
rivers and large streams to the fast water of smaller streams.
This species appears to be restricted to the Finger Lake
Region and the Susquehanna watershed of central New
York (Fig. 189) although it has often been reported else-
where because of misidentification (Burks 1953). Possibly
additional collecting and study of museum specimens may
result in extending the distribution.
Specimens Examined: NEW YORK —Beaver Creek,
Chicago, 20VI32, 1 male, 1 female (reared) (Traver); Fish
Hatchery, Ithaca, 5IV31, 2 males, 2 females (reared); same
location, 16VI31, 1 male, 1 female (Sadler); Ithaca, 1VI85,
1 male; Cass Creek, Ithaca, 21VI13, 1 male (Holotype)
(Clemens); same location, 7VI14, 1 male, 1 female (Para-
types) (Clemens).
DISCUSSION
The use of characters given in the keys of this manual
will, for the first time, separate both the adults and nymphs
from the dark form of 5. rubromaculatum with which this
species has previously been confused.
Stenonema lepton Burks
Stenonema lepton Burks, 1946: 614; Burks, 1953: 176
NYMPH: Unknown.
MALE IMAGO: Burks (1953) has adequately described
the male of this species.
Genitalia with no discal or terminal spines on the penis lobes.
ECOLOGY AND DISTRIBUTION
Nothing is known of the ecology of this species. The type
series was collected near an unpolluted reach of the Kanka-
kee River and it seems to be endemic to that river system
(Fig. 191).
Specimens Examined: ILLINOIS — Kankakee River,
Momence, 24VI39, 1 male (Paratype) (Burks and Ayars).
DISCUSSION
There is some doubt as to the status of 5. lepton. The
nymph of S. lepton is not known, and the adult is close to
S. terminatitm. Adults differ from 5. terminatum in having
a fore tarsal ratio of 1.2-1.5 rather than 2.0-2.3, the range
of S. terminatum. The penis lobes of 5. lepton have only
1 spine each (the inner apical) whereas S. terminatum has
2 spines.
Stenonema luteum (Clemens)
(Figures 20, 34, 45, 77, 98, 111, 142, 144, 188)
Heptagenia lutea Clemens, 1913: 252; 1915: 135
Ecdyonurus luteus McDunnough, 1933: 34
Stenonema luteum Traver, 1935: 319; Burks, 1953: 175
NYMPH: Length 10 mm.
Head: Light brown sprinkled with white dots, white spots
surrounding ocelli and on meson at posterior margin, large
white area lateral to each compound eye; maxilla with 2-4
pectinate spines and 30-40 setae on crown, 18-25 lateral
setae (Fig. 77); mandibles each with 6 or 7 teeth on inner
margin of outer canine (Fig. 98).
Thorax: Light brown with numerous irregular light spots,
lateral border of pronotum hyaline; legs fringed with long
hairs along posterior margins, femora with alternately light
and dark irregular bands and covered with minute spines
dorsally, venter of femora white, tibiae with basal and
median brown bands, tarsi with basal brown band, claws
pectinate (Fig. 111).
Abdomen: Dark brown with varying amounts of white
coloration; terga 1-3 mostly white, remaining segments with
complicated pattern of brown and white (see Figs. 20 and
34); sterna 2-8 pale with dark lateral and posterior margins
(Fig. 45), segments 8 and 9 with two large brown spots
often connected at posterior margins; gills 1-6 truncate at
apices, 7th gill fringed with long hairs but lacking tracheae;
posterolateral angles of segments 3-9 extended as spines;
caudal filaments greenish-white basally, beyond middle each
two segments alternately dark and white.
MALE IMAGO (Fig. 144): See either Burks (1953) or
Traver (1935) for a complete description.
Genitalia with large terminal and apical spines on penis lobes
(Fig. 188).
ECOLOGY AND DISTRIBUTION
This is a northern species that inhabits lake shores and
rapids of rivers of southern Canada and the northern states
west of the Great Lakes (Fig. 193). It is apparently a clean
water form.
Specimens Examined: ILLINOIS — Mississippi River,
Savanna, 29VI35, 1 male (Delong and Ross). WISCON-
SIN—Fourteen Mile Creek, Friendship, 31X68, 1 nymph
(Hilsenhoff); W. Branch Pecatonica River, Lafayette Co.,
27IV72, 1 male (Flowers). CANADA — Go-Home-Bay,
Ontario, 29VI12, 1 male (Holotype) (Clemens) (this
specimen was designated as Holotype by McDunnough in
1933); same location, 21VII24, 1 male (Ide); same location.
30VI32, 1 male (reared) (Walley); Ottawa, Ontario, 4VI22,
1 male (Homotype) (Clemens).
28
-------
DISCUSSION
Nymphs of this species are quite variable in the amount
of dark shading on the terga and along the posterior mar-
gins of the sterna. Nymphs from Wisconsin identified as
S. liiteum by Ide may represent an undescribed species. The
characteristic dark band along the posterior margins of
each sternum is missing from these Wisconsin nymphs. A
male imago reared from one of these nymphs has oblique
grey spiracular dashes (Fig. 142), whereas the types have
no spiracular markings. Most specimens from both popula-
tions can be identified by characters used in the key.
Stenonema mediopunctatum (McDunnough)
(Figures 22, 44, 78, 102, 141)
Ecdyonurus mediopunctatus McDunnough, 1926: 191
Stenonema mediopunctatum Traver, 1935: 321; Burks, 1953:
174
NYMPH: Length 7-9 mm.
Head: Brown speckled with pale dots, 2 pale spots lateral
to each compound eye separated by a narrow brown band;
maxilla with 4-6 pectinate spines and 1-5 setae on the
crown, 25-40 lateral setae (Fig. 78); mandibles each with
7-8 teeth on inner margin of outer canine (Fig. 102).
Thorax: Brown with small pale dots; legs white with ir-
regular brown spots forming bands across femora, brown
bands on tibiae at base and middle, claws not pectinate.
Abdomen: With terga 1-4, 6, 8-10 predominately brown,
terga 5 and 7 mostly white (Fig. 22); sterna 4-8 (often 2
and 3 also) pale with a curved brown cross bar near each
anterior margin (sometimes entire anterior half of each
sternum is dark brown), sternum 9 with U-shaped brown
mark with open end directed posteriorly (anterior end of
U not always completely closed) (Fig. 44); gills 1-6 trun-
cate at apices, 7th gill with fringe of hairs but without
tracheae; posterolateral angles of segments 3 (or 5)-9 ex-
tended as spines; caudal filaments pale with articulations
darker.
MALE IMAGO (Fig. 141): Length 9 mm.
Head: Whitish anterior to compound eyes, becoming light
brown on vertex.
Thorax: Deep black-brown; mesoscutellum black-brown
with light brown tip; legs white with median and apical
purplish bands on femora, fore tarsal ratio 1.5-1.8; fore
wing hyaline with 1 or 2 cross veins in each of the first 3
interspaces; hind wing without dark band at apex.
Abdomen: White; terga 2-7 each with a small transverse
black dash on meson at posterior margin, black spiracular
dots on segments 4-7, segments 8-10 opaque white shaded
with brown; genitalia with small terminal spines and minute
apical spines on penis lobes; caudal filaments entirely white.
ECOLOGY AND DISTRIBUTION
The reported distribution of this species is limited to the
area just north and west of the Great Lakes (Fig. 195).
Nymphs have been collected only from clean water streams.
Specimens Examined: NEW YORK — Niagara River,
Buffalo, no date, 1 female. WISCONSIN — Apple River,
Little Falls, 19VI68, 1 nymph (Hilsenhoff); Moose Ear
Creek, Barren, 21V69, 1 nymph (Hilsenhoff); Turtle Creek,
Turtle Lake, 27V69, 1 nymph (Hilsenhoff). CANADA —
Stream 40 mi SE of Kenora, Ontario, 28VI68, 1 male
(Flannagan); Walsh, Ontario, no date, 1 male (Holotype)
(Walley); Victoria Harbor, Ontario, no date, 1 male (Para-
type).
DISCUSSION
A description of the nymph of this species has not been
published, and its inclusion in the key is based on several
nymphs from Wisconsin identified by Ide, who said that he
can separate the nymphs of this species from the closely
related S. nepotellum (personal communication). Adult
characters used in the key are based on the holotype and
a paratype. Something of the problem involving the rela-
tionship between S. mediopunctatum and 5. nepotellum can
be gathered from the fact that Daggy (1941) reported S.
nepotellum common in Minnesota but did not collect any
S. mediopunctatum, whereas Krueger (1969) reported S.
mediopunctatum common in Wisconsin but reported no S.
nepotellum. The specimens reported by both these workers
appear to be similar to those identified by Ide as S. medio-
punctatum, and I will accept his identifications until they
are shown to be in error. It is possible that 5. nepotellum
is a southern form of S. mediopunctatum as discussed under
that species. Rearing and comparative studies will be needed
to resolve this problem.
Stenonema minnetonha Daggy
(Figures 60, 80)
Stenonema minnetonka Daggy, 1945: 376; Burks, 1953: 164
NYMPH: Length 8-10 mm.
Head: Anterior to compound eyes uniform brown with a
pale spot usually present on anterior margin at meson, 2
large pale spots lateral to each eye separated by brown
band; maxilla with 9-10 pectinate spines on crown, 30-40
lateral setae (Fig. 60); mandibles each with 6-7 teeth on
inner margin of outer canine; inner margin of inner canine
with 3-4 blunt teeth (Fig. 80).
Thorax: Brown with a few pale areas on pronotum; legs
brown, each femur with a basal, median, and apical white
cross band, each tibia white near base and at apex, claws
not pectinate.
Abdomen: Brown; terga 1-10 each with a pair of submed-
ian longitudinal pale streaks forming continuous stripes,
those on terga 8 and 9 widest and those on tergum 10 much
reduced; sterna 4-8 with lateral margins brown, posterior
fourth of tergum 9 brown; gills 1-6 pointed at apices, 7th
gill with tracheae but without a fringe of hairs; postero-
lateral angles of segments 7-9 extended as spines; caudal
filaments light brown in basal half, alternating dark and
light segments apically.
MALE IMAGO: See Burks (1953) for complete de-
scription.
Genitalia are distinctive in that the apical spine on each
penis lobe is larger than the terminal spine, just the reverse
of the related species (See Burks, 1953, his figure 335).
ECOLOGY AND DISTRIBUTION
Nymphs that are believed to be this species were col-
lected and reared from a small creek in southwest Ohio,
but the type series and other adults reported as this species
were taken near large rivers in Minnesota and Illinois (Fig.
195).
Specimens Examined: ILLINOIS — Rockford, 22V41, 1
male (Ross and Burks). KENTUCKY — Beargrass Creek,
Louisville, 3V138, 1 male (Burks). OHIO —Kain Run,
Williamsburg, 27V71, 2 females (reared) (Lewis); Little
Miami River, Loveland, 10X68, 1 female (Lewis).
DISCUSSION
This species has previously been known only from a few
adults collected along the Mississippi and Rock Rivers in
29
-------
southern Minnesota and northern Illinois. The nymphal
description given above was based on the exuvia of a reared
female from Kain Run, Ohio; therefore, this description
must be considered tentative until substantiated by positive
association with a'reared male. As yet I have not been
able to examine the type series to determine its relationship
to the 5. interpunctatum complex from which it differs pri-
marily in the arrangement of spines on the genitalia. In
5. interpunctatum, the apical spine is either completely
missing or, if present, much smaller than the terminal spine
(Fig. 169). In contrast, the apical spine of 5. minnetonka
is at least as large as the terminal spine. Additional col-
lection and rearing will be needed to fix the status of S.
minnetonka with certainty.
Stenonema modestum (Banks)
(Figure 174)
Epeorus modestus Banks, 1910: 202
Iron modestus McDunnough, 1924: 129; Traver, 1935: 406
Stenonema modestum Burks, 1953: 155
NYMPH: Unknown.
MALE IMAGO: Length 6-7 mm.
Head: White.
Thorax: Dark brown; mesoscutellum brown; legs pale, each
femur with median and apical brown bands, apex of each
tibia black, fore tarsal ratio 1.1-1.3; fore wing hyaline with
cross veins not crowded in bulla region; hind wing not dark
banded at apex.
Abdomen: Pale; terga with dark spiracular dots and nar-
row black lines at posterior margins, terga 9-10 dark red-
dish-brown; genitalia with a minute apical and small discal
spine on each penis lobe (Fig. 174); caudal filaments pale,
alternating joints dark.
ECOLOGY AND DISTRIBUTION
The holotype was taken in the vicinity of the Potomac
River where the nymphs probably developed (Fig. 192).
Specimens Examined: DISTRICT OF COLUMBIA —
Washington, no date, 1 male (Holotype) (Banks).
DISCUSSION
This species is so similar to 5. rubrum in appearance that
specimens cannot be distinguished except by fore tarsal
ratio and arrangement of spines on the genitalia. The fore
tarsal ratio of 5. modestum is 1.1-1.3 compared with 1.7
for S. rubrum. Compare figures 174 and 185 for differences
in the genitalia.
Stenonema modestum has not been reported since the
types were collected in 1910; however, S. rubrum nymphs
have been reported regularly from the Potomac River.
Rearing of 5. rubrum nymphs from the Potomac River
might clear up the uncertain status of S. modestum.
Stenonema nepotellum (McDunnough)
(Figures 42, 68, 108, 145, 162, 186)
Ecdyonurus nepotellus McDunnough, 1933: 20
Stenonema nepotellum Traver, 1935: 322; Burks, 1953: 177
NYMPH: Length 7-9 mm.
Head: Brown with large pale spots lateral to compound
eyes; maxilla with 4-6 pectinate spines but without setae on
crown, 25-30 lateral setae (Fig. 68); mandibles each with
8 teeth on inner margin of outer canine (Fig. 108).
Thorax: Brown, pronotum with large pale area at each
lateral margin; legs brown dorsally with 3 irregular white
bands on each femur, claws pectinate.
Abdomen: Brown with a few vague pale areas; terga 5 and
7 predominantly pale, others mostly dark brown; sterna
2-8 white with dark brown cross bar near each anterior
margin (sometimes anterior half of sterna dark), sternum
9 with U-shaped brown mark, open posteriorly (Fig. 42);
gills 1-6 truncate at apices, 7th gill with fringe of hairs but
lacking tracheae; posterolateral angles 5-9 extended as
spines; caudal filaments light brown basally, alternating
pairs of light and dark segments apically.
MALE IMAGO (Fig. 145): See Burks (1953) for com-
plete description.
Fore wing with cross veins slightly crowded at bulla (Fig.
162); genitalia with minute apical spine and large terminal
spine on penis lobes (Fig. 186).
ECOLOGY AND DISTRIBUTION
The distribution (Fig. 197) of this species is in doubt be-
cause of the confusion in the taxonomy of the species. Most
records from the midwestern and southeastern states are
probably reliable, but the Minnesota records and some of the
Canadian records of 5. nepotellum must be questioned be-
cause of its confusion with 5. mediopunctatum. The nymphs
seem to prefer medium sized streams with a moderate cur-
rent flowing over bedrock. They are able to tolerate moderate
amounts of organic enrichment.
Specimens Examined: ILLINOIS — Nippersink Creek,
Spring Grove, 21VI38, 1 male, 1 nymph (Ross and Burks).
INDIANA — Sugar Creek, London, 4VIII69, 4 females
(reared), 5 nymphs (Lewis). KENTUCKY —W. Fork
Drakes Creek, Franklin, 21V71, 7 males (reared), 4 fe-
males (reared) (Myers); same location, 3V71, 1 male
(Myers); same location, 18V71, 1 male (Myers); same
location, 20V71, 1 male (Myers). MISSOURI — Shoal
Creek, Joplin, 7VIII57, 1 nymph (Peters). TENNESSEE
—Duck River, Powers Bridge, 8VIII72, 1 nymph (Sinclair).
CANADA — Fulford, Quebec, 15VIII30, 1 male (Holo-
type) (Milne); same location, no date, 1 male (Paratype)
(Milne).
DISCUSSION
Adults of 5. nepotellum are quite similar to S. annexum
and S. rubrum but differences in the arrangement of spines
on the penis lobes are diagnostic. A series of 38 male
imagos collected by Frank Myers from Simpson County,
Kentucky, contained both S. nepotellum and S. annexum.
Although differences in the genitalia remained constant,
there was considerable variation in both size and color.
Nymphs from the same creek show equal amounts of varia-
bility, but there was no concrete evidence of interbreeding.
There is the possibility that 5. nepotellum is a southern
form of 5. mediopunctatum, as discussed under that species.
The nymphs are very similar and differ only in the number
of setae on the crown of the maxilla and amount of ven-
tral maculation. The adults differ slightly in color intensity
and in details of the arrangement of spines on the penis
lobes.
Stenonema pallidum Traver
(Figures 57, 83, 120, 165)
Stenonema pallidum Traver, 1933: 181; Traver, 1935: 323
Stenonema interpunctatum interpunctatum Spieth, 1947: 106
(unjustified
synonymy.)
NYMPH: Length 6-8 mm.
Head: Reddish brown, pale spot anterior to median ocellus
and lateral to each lateral ocellus; maxilla with 11-13 pec-
tinate spines on crown, approximately 25 lateral setae (Fig.
57); mandibles each with 5-8 teeth on inner margin of
outer canine, 2 blunt teeth on inner margin of inner canine
(Fig. 83).
30
-------
Thorax: Reddish brown with pale areas near lateral and
anterior margins of pronotum; legs white, each femur with
3 irregular brown bands, claws not pectinate.
Abdomen: Reddish brown with submedian pale streaks
consisting of a series of elongate spots such as in S. gil-
dersleevei, but in this species, the spots are connected to
form continuous lines; terga with black bands at posterior
margins; sterna 4-8 dark at lateral margins, sternum 9 dark
at posterior and lateral margins; gills 1-6 pointed at apices,
7th gill with tracheae but without fringe of hairs; postero-
lateral angles of segments 7-9 extended as spines; caudal
filaments pale tan.
MALE IMAGO (Fig. 120): See Traver (1935) for com-
plete description.
Genitalia are illustrated in Fig. 165.
ECOLOGY AND DISTRIBUTION
This species has been collected only in the mountains of
North Carolina (Fig. 193). Nymphs inhabit swift mountain
streams and appear to be intolerant of pollution.
Specimens Examined: NORTH CAROLINA — The Cas-
cades, Danbury, 21V29, 1 male (Paratype) (reared)
(Traver); Watauga River, Valle Crucis, 7VI36, 1 nymph
(Traver).
DISCUSSION
This species is superficially similar to 5. interpunctatum,
which apparently prompted Spieth (1947) to synonymize
it with that species. Examination of the holotype and its
nymphal exuvia reveals that Spieth's synonymization of
this species with S. interpunctatum interpunctatum was un-
justified. In the adult, the arrangement and shape of the
spines on the penis lobes of the genitalia differ noticeably
from 5. interpunctatum interpunctatum (compare Figs. 169
and 165). Nymphs differ in having 11-13 pectinate setae
on the crown of the maxillae compared with 9 or 10 for
S. interpunctatum nymphs. Additional rearing may ulti-
mately result in proving this species to be synonymous with
S. interpunctatum or 5. gildersleevei, but until such proof is
available S. pallidum should be considered a distinct species.
Stenonema placitum (Banks)
(Figure 180)
Heptagenia placita Banks, 1910: 199
Stenonema placitum Traver, 1935: 324; Burks 1953: 175
NYMPH: Unknown.
MALE IMAGO: See Traver (1935) for complete de-
scription.
Genitalia with small to minute apical spines and very large
subterminal spines on penis lobes (Fig. 180).
ECOLOGY AND DISTRIBUTION
Adults of this species have been reported from northern
New York and southern Quebec Province (Fig. 192) in
areas where little pollution exists.
Specimens Examined: NEW YORK—Sport Island, Sacan-
daga River, no date, 1 male (Holotype) (Alexander). CAN-
ADA—Vaudreuil, Quebec, 23VI30, 1 male (Walley).
DISCUSSION
Burks' (1953) synonymization of S. placitum with S.
terminatum seems unjustified because of the unique char-
acter of the male genitalia and differences in the fore tarsal
ratio. The subterminal spine of each penis lobe of 5. placi-
tum is large and wide at the base whereas that of S. termi-
natum is small and narrow. The fore tarsal ratio of males
of 5. placitum is 1.8, whereas 5. terminatum has a fore
tarsal ratio of 2.2. Discovery of the nymph and rearing of
S. terminatum and S. placitum should yield answers to the
questions concerning the relationship between these 2
species.
Stenonema pudicum (Hagen)
(Figures 26, 43, 71, 99, 118, 136, 137, 158, 181)
Ephemera pudica Hagen, 1861: 39
Ecdyonurus pudicus McDunnough, 1925: 191 (not synonym
of S. vicarium)
Stenonema pudicum Traver, 1935: 326; Burks, 1953: 171
NYMPH: Length 12-14 mm.
Head: Dark brown, freckled with pale dots, area lateral
to compound eyes pale; maxilla with 5-8 pectinate spines
and 20-40 setae on crown, 20-40 lateral setae (Fig. 71);
mandibles each with 10-11 teeth on inner margin of outer
canine (Fig. 99).
Thorax: Dark brown, pronotum with large pale areas near
lateral margins; legs mostly brown with irregular white areas
on femora, claws without pectinations (Fig. 118).
Abdomen: Ground color brown; terga 6 and 8-10 usually
with much more brown than other terga (Fig. 26); sterna
4-8 pale usually with broad dark brown crossbands on
median portions near anterior margins, sternum 9 dark
brown at posterior margin and near each lateral margin
(Fig. 43); posterolateral angles of segments 3 (or 4)-9 ex-
tended as spines; Caudal filaments yellow or tan.
MALE IMAGO (Figs. 136 and 137): See Burks (1953)
or Traver (1935) for complete description.
Fore wing hyaline, stigmatic area shaded with red-brown,
cross veins in bulla region crowded in first six interspaces
(Fig. 158); genitalia are shown in Fig. 181.
ECOLOGY AND DISTRIBUTION
This species is common in the mountains of the eastern
states from New York to North Carolina and Tennessee
(Fig. 198). Reports from states west of the Mississippi and
Ohio Rivers are questionable. All specimens labeled 5. pudi-
cum from the central states (Illinois and Oklahoma) that I
have examined were misidentified specimens of S. tripuncta-
tum and 5. nepotellum. Present evidence indicates that 5.
pudicum is intolerant of pollution.
Specimens Examined: NORTH CAROLINA — Yadkin
River, Blowing Rock, 23V40, 1 nymph (Prison). PENN-
SYLVANIA— E. Branch White Clay Creek, Avondale,
26V70, 2 males, 1 female (reared) (Richardson); same
location, 18X1169, 1 male (reared) (Richardson); Marvina
Creek, Marvindale, 23VII69, 1 nymph (Lewis); Minister
Creek, Sheffield, 23V1I69, 1 nymph (Lewis). TENNESSEE
— Little Pigeon River, Greenbrier Cove, 7V39, 1 female,
1 male (Cole). VIRGINIA — Lynch River, Standardsville,
21III40, 1 nymph (Prison and Mohr). DISTRICT OF
COLUMBIA—Washington, no date (1858), 1 male ("Type")
(Hagen).
DISCUSSION
Traver (1935) noticed that images of S. pudicum from
South Carolina lacked the sagittate dark median marks so
characteristic of specimens from further north. She chose
to hold these specimens as S. pudicum because the nymphs
were not yet known. Recently Carlson (Florida A&M Uni-
versity) (personal communication) reared adults of this
light phase from nymphs taken from Wildcat Creek, South
Carolina, and found striking differences in the nymphal
mouthparts. Therefore, this southern form has been de-
scribed as S. carlsoni (Lewis, 1974).
31
-------
Stenonema pulchellum (Walsh)
(Figures 12, 13, 49, 66, 91, 92, 114, 143, 156, 178)
Palingenia pulchella Walsh, 1862: 375
Stenonema pulchellum Traver, 1935: 327; Burks, 1953: 179
NYMPH: Length 7-9 mm.
Head: Dark brown freckled with numerous white dots, pale
spot lateral to each compound eye and on meson at poster-
ior margin; maxilla with 4-6 pectinate spines but without
setae on crown, 20-30 lateral setae (Fig. 66); mandibles
each with 6-7 teeth on inner margin of outer canine (Figs.
91 and 92).
Thorax: Brown, pronotum with 2 or 3 large pale spots
near each lateral margin; legs white, each femur with 2
brown bands dorsally, each tibia with basal and median
dark-brown bands, basal half of tarsi brown, claws pecti-
nate (Fig. 114).
Abdomen: Distinct pattern of brown and white areas; terga
6, 8, and 10 almost entirely dark brown, terga 1-5 white
with brown markings, tergum 7 mostly white with brown
markings near lateral margins and on meson, tergum 9
brown with large submedian white areas; sterna 1-8 en-
tirely white, sternum 9 white with brown lateral margins
(Fig. 49), sterna 8 and 9 sometimes with median brown
spot at anterior margins; gills 1-6 truncate at apices (Fig.
12); 7th gill with fringe of hairs but without tracheae (Fig.
13); posterolateral angles of segments 7-9 extended as
spines; caudal filaments brown basally, alternating pairs of
light and dark segments apically.
MALE IMAGO (Fig. 143): See either Traver (1935) or
Burks (1953) for complete description.
Fore wing hyaline, pale brown stain in stigmatic area, cross
veins not crowded (Fig. 156); genitalia with apical spine
usually larger than subterminal spine (Fig. 178).
ECOLOGY AND DISTRIBUTION
S. pulchellum nymphs are very common in streams in the
Ohio River Basin where there is moderate current. The
distribution of S. pulchellum parallels S. interpunctatum s.s.
forming a half circle beginning in Ontario and extending
south of the Great Lakes and ending in Wisconsin and
Minnesota (Fig. 199). It is most common in the 4 states at
the bottom of the half circle. Nymphs of this species, listed
as facultative by Gaufin (1958), are quite tolerant to pollu-
tion. They were common in baskets that had a septic odor
when recovered from the bottom of the Little Miami River.
Nymphs were collected in both clean water and in polluted
reaches during this study where the TDS ranged from 255-
800 ppm and the pH ranged between 7.5-8.5.
Specimens Examined: ILLINOIS — Vermilion River,
Danville, 23V67, 1 nymph (Anderson); Rock Island, no
date, 1 male (Type) (Walsh). INDIANA — Flatrock Creek,
Omar, 4VIII69, 2 nymphs (Lewis); Mississinewa River,
Peru, 11X66, 1 nymph (Anderson); Sand Creek, Columbus,
6V70, 1 nymph (Lewis); Wabash River, Lockport, 5VIII69,
1 nymph (Lewis). KENTUCKY — Cumberland River, Cum-
berland Falls, 241X69, 2 nymphs (Lewis). OHIO — Kain
Run, Williamsburg, 17V71, 1 male (Lewis); same location,
27V71, 1 female (Lewis); Little Miami River, Cincinnati,
6VI67, 1 male, 6 females, 2 nymphs (Lewis); same loca-
tion, 18VII68, 5 males, 5 females, 1 nymph (Lewis); same
location, 16169, 1 male (reared), 2 nymphs (Lewis); Little
Miami River, Batavia, 18II69, 1 nymph (Lewis); Mad
River, West Liberty, 171X69, 1 nymph (Lewis); Ohio River,
Cincinnati, 4XII67, 1 male (reared) (Mason); Turkey Run
Creek, Friendship, 6X69, 1 nymph (Lewis).
DISCUSSION
Past separation of the adults of 5. pulchellum and 5. rub-
rum was based almost entirely on color characters, a practice
that has been found to be unreliable in other groups. Only
slight differences could be discovered in the genitalia of
museum specimens identified as these species by Burks and
McDunnough. Although the characters used to separate
adults of 5. pulchellum and 5. rubrum in this key are not en-
tirely satisfactory, the nymphs are easily separated by char-
acteristics of the mouthparts. There was very little variability
among two dozen S. pulchellum nymphs collected from the
Little Miami River and reared to adults, and both forms
keyed out well using the present key. Additional study is
needed to determine if the 2 species are part of a polytopic
complex of subspecies such as occurs in 5. interpunctatum.
Stenonema quinquespinum Lewis
(Figures 24, 50, 65, 104, 138, 176)
Stenonema quinquespinum Lewis, 1974: 353
NYMPH (Fig. 24): Length 9-10 mm.
Head: Anterior to eyes and on vertex between eyes dark
brown with numerous freckle-like white dots, some of white
dots converge forming irregular pale spots. Area lateral to
compound eye divided into 2 large pale spots by a brown
band; each ocellus surrounded by large pale spot (middle
one shaped like arrowhead), a small pale spot on vertex
near posterior margin of head. Scape of antenna pale,
following 2 segments black, and remainder of antenna pale;
maxilla with 4-6 (usually 5) pectinate spines but without
setae on crown, 20-30 lateral setae (Fig. 65); mandibles
each with 7-8 teeth on inner margin of outer canine (Fig.
104).
Thorax: Brown with a few small pale spots mostly in the
mid-dorsal region, large pale spots at each lateral margin
of pronotum extending anteromedially nearly to the anterior
margin, a large pale spot near anterior margin midway
between lateral margin and mid-dorsal line, legs with pale
femora each with 2 or 3 irregular brown bands across
dorsal surface and some brown shading at apex, each tibia
with a basal and median brown band, basal half of each
tarsus brown, a dense row of hairs along posterior margins
of fore legs, claws not pectinate.
Abdomen: With terga 1 and 2 mostly white, terga 7 and
9 pale on meson but dark brown laterally and with brown
submedian spots near anterior margins, terga 6, 8, and 10
mostly brown with segment 10 darkest, remaining terga
brown with pale dots posteriorly and wide pale areas near
anterior margins; sterna 1-7 pale usually without dark
markings, segments 8-9 usually with brown bands near
lateral margins and brown spot on meson at anterior mar-
gins, segment 9 sometimes with brown band around pos-
terior margin (Fig. 50); gills 1-6 truncate at apices, 7th
gill with fringe of hairs but without tracheae; posterolateral
angles of segments 7-9 produced as spines, those on segment
9 very small; caudal filaments banded with 2 segments pale
and 2 segments brown alternating for length of filaments.
MALE IMAGO (Fig. 138): Length 9 mm.
Head: Below antennal sockets white, vertex yellow with
varying amounts of orange shading especially on posterior
portion, eyes grey in life turning black in alcohol.
Thorax: Yellow-brown, pale area on meson of mesonotum,
pleuron white with pink or orange areas near coxae; meso-
scutellum white; legs with fore femora light tan, remainder
of legs white, each femur with red-brown bands at middle
and apex, apex of each tibia black, fore tarsal ratio 1.6;
32
-------
fore wing hyaline, stigmatic area stained with red-brown;
hind wing with narrow brown band at apical margin.
Abdomen: White; terga 2-7 each with a narrow black line
at posterior margin and small oblique black spiracular
spots, terga 8-10 alabastar white especially in mid-dorsal
area; genitalia with apical and discal spines (Fig. 176);
caudal filaments white with dark brown joints.
ECOLOGY AND DISTRIBUTION
Nymphs inhabit middle reaches of medium sized rivers
from Georgia to Wisconsin (Fig. 198). Most of the streams
from which this species was collected were effected by agri-
cultural runoff and mild organic enrichment. However, this
species is often replaced by S. pulchellum in more polluted
areas below sewage discharges.
Specimens Examined: GEORGIA — Oostanaula River,
Rome, 15VII39, 2 males (Fattig) (these specimens were
labeled S. exiguum and were presumed to be topotypes of
that species). INDIANA — Wildcat Creek, Carroll Co.,
4VIII69, 2 nymphs (Lewis). OHIO — East Fork Little
Miami River, Williamsburg, 1V72, 10 males (reared), 10
females (reared), 5 nymphs (includes Holotype, Allotype,
and Paratypes) (Lewis). WISCONSIN — Clam River, Bur-
nett Co., 3IV72, 1 male (Flowers); same location, 26VI72,
1 nymph (Flowers).
DISCUSSION
Stenonema quinquespinum is closely related to S. exiguum
and S. pulchellum. However, S. quinquespinum can be sep-
arated from S. pulchellum by the narrow apical brown border
on the hind wing and the absence of terminal spines on penis
lobes. The presence of dark stigmal spots separates this
species from S. exiguum, and differences in spination of
penis lobes also appear to be diagnostic. Each penis lobe of
S. exiguum has a subterminal spine, whereas S. quinque-
spinum possesses a discal spine. Differences in wing veination
and genitalia separate this species from S. integrum, and the
absence of 2 dark dashes at the posterior margins of terga
2-8 serve to distinguish it from S. ares and S. bipunctatum.
Nymphs could be confused with S. exiguum except for
the lack of pectinations on the claws. They are separated
from S. pulchellum by the band of large white spots across
the mesonotum at the wing bases.
Stenonema rubromaculatum (Clemens)
(Figures 30, 40, 76, 103, 113, 183)
Heptagenia rubromaculata Clemens, 1913: 256
Ecdyonurus rubromaculatus McDunnough, 1933: 16
Stenonema rubromaculatum Traver, 1935: 329; Burks, 1953:
178
NYMPH (Fig. 30): Length 8-10 mm.
Head: Dark brown sprinkled with small pale dots, lateral
margins pale in posterior half, this pale area cut in half by
a transverse dark band; maxilla with 4-6 pectinate spines
and 30-50 setae on crown, 20-35 lateral setae (Fig 76);
mandibles each with 8-9 teeth on inner margin of outer
canine (Fig. 103).
Thorax: Dark brown sprinkled with small pale dots; legs
very hairy at posterior and anterior margins, dorsum of each
femur with 4 irregular dark bands separated by pale areas,
white ventrally, claws pectinate (Fig. 113).
Abdomen: Brown; terga sprinkled with many small pale
dots, without conspicuous color pattern; sterna pale with
dark markings variable, usually with 2 pairs of median dots
and a pair of lateral dots, these dots often joined by an
oblique dark line, in dark-phase nymphs (midsummer) the
space between dots and oblique band fills with dark pigment
forming mushroom-like markings similar to S. ithaca (Fig.
40), sternum 9 with dark lateral borders and a dark streak,
or blotches, near anterior margin forming 3 sides of a
square; gills 1-6 truncate at apices, 7th gill with fringe of
hairs but without tracheae; posterolateral angles of segments
3-9 extended as spines; caudal filaments brown.
MALE IMAGO: Length 8-9 mm.
Head: Whitish on face with faint dark dash on each side
of carina below antennae, vertex pale creamy-yellow.
Thorax: Light olive gray or pale clay colored, mesoscutel-
him white; legs white with median and apical dark bands on
femora; fore tarsal ratio 1.6-2.2; fore wing hyaline with
reddish shading in stigmatic area, cross veins in bulla region
moderately crowded (usually 2, 2, 3 in costal, subcostal,
and radial interspaces respectively); hind wing without dark
band at apex.
Abdomen: Terga 1-7 hyaline, a narrow transverse dark
band across posterior margin of each, terga 8-10 opaque
white shaded with pinkish brown near median line, in dark-
phase males this brown shading also covers half or more
of terga 2-7 as in S. fuscum, dark spiracular dots on terga
2-7; genitalia similar to 5. nepotellum with a hook-like
terminal spine and a minute apical spine on each penis lobe
(Fig. 183); caudal filaments white with dark brown joints.
ECOLOGY AND DISTRIBUTION
The distribution of this species is restricted to the north-
eastern United States and southeastern Canada (Fig. 200)
corresponding to that of S. interpunctatum frontale. Nymphs
inhabit small streams where there is moderate to fast current.
Although I collected several of these nymphs in a very
small stream clinging to the bottoms of rocks where the
water was only an inch deep and nearly stagnant, I have
never collected specimens from polluted waters. They are
probably clean-water forms.
Specimens Examined: ILLINOIS—Vermilion River, Oak-
wood, 6VI25, 1 male, 1 female (McDunnough). MAINE
— Carsley Brook, Harrison, 2VII69, 1 female, 1 nymph
(Lewis); same location, 12VII71, 1 male, 3 females (reared),
3 nymphs (Lewis); Crooked River, Harrison, 14VII71, 1
nymph (Lewis). PENNSYLVANIA—Avondale, 28VI70, 1
male (Richardson); same location, 4VI70, 1 male (Richard-
son). VERMONT — Brown River, Essex Center, 2X60, 1
nymph (Bean). CANADA—South Bolton, Quebec, 20VI30,
1 female (Milne); Go-Home River, Ontario, no date, 1
male (Holotype), 1 female (Allotype) (Clemens); same
location, 10VII32, 1 male (reared) (Walley); Severn, On-
tario, 22VI25, 1 male (McDunnough).
DISCUSSION
The two color phases exhibited by both the nymphs and
adults of this species have been primarily responsible for
the confusion concerning the taxonomy of this species,
which has been variously identified as S. ithaca, S. fuscum,
S. pulchellum, or 5. nepotellum. The light phase adult is
very similar to S. pulchellum and 5. nepotellum, and the dark
phase has been confused with S. fuscum. Light-phase nymphs
are usually quite easy to identify, but the dark phase has
been identified as S. ithaca by most previous workers. Both
phases can be properly placed by using the characters in the
keys of this manual. It has been suggested (and it is admit-
tedly possible) that the light and dark phases are two dis-
tinct species. At present, I consider them variants of one
species. I have collected nymphs of the dark phase of 5. rub-
romaculatum and nymphs of S. ithaca from the same streams
near Ithaca, New York, thinking that everything I was col-
lecting was 5. ithaca. Upon rearing the nymphs, I found that
33
-------
2 species were involved and found, upon close study of the
nymphal mouth parts, that these nymphs could be easily
separated by the presence or absence of setae on the crowns
of the maxillae.
Stenonema rubrum (McDunnough)
(Figures 32, 51, 74, 100, 112, 164, 185)
Ecdyonurus ruber McDunnough, 1925: 192
Stenonema rubrum Traver, 1935: 330; Burks, 1953: 178
Stenonema varium Traver, 1933: 192; 1935: 333 NEW
SYNONYMY
NYMPH (Fig. 32): Length 8-9 mm.
Head: Brown with 2 pale areas lateral to compound eyes;
maxilla with 4-5 pectinate spines and 15-35 setae on crown,
15-25 lateral setae (Fig. 74); mandibles each with 7-9 teeth
on inner margin of outer canine (Fig. 100).
Thorax: Brown; legs brown banded with obscure pale areas,
claws pectinate (Fig. 112).
Abdomen: Often uniform brown; terga sometimes with
median lighter spots faintly indicated especially on tergum
7; sterna 1-7 usually entirely white, sternum 8 often with a
median dark brown spot at anterior margin (on southern
forms this spot usually expanded to form a crescent-shaped
crossbar on sterna 7 and 8 as in Fig. 51), sternum 9 with
U-shaped dark brown mark open posteriorly; gills 1-6 trun-
cate at apices, 7th gill with fringe of hairs but lacking
tracheae; pasterolateral angles of segment 7-9 extended as
spines; caudal filaments uniformly tan except beyond the
middle where alternating pairs of segments are light and
dark.
MALE IMAGO: See Burks (1953) for complete descrip-
tion.
Fore wing hyaline, faint pink shading in stigmatic area, no
crowding of cross veins in bulla area (Fig. 164); genitalia
with apical and subterminal spines similar in size and shape
(Fig. 185).
ECOLOGY AND DISTRIBUTION
5. rubrum is common west and north of the Great Lakes
where its distribution parallels that of 5. interpunctatum
canadense; it extends through the Appalachian Mts. to
Florida (Fig. 201). It seems to be very common in Minne-
sota and Wisconsin where it inhabits rivers and larger streams
with moderate to fast current. Bell (1969) found the nymphs of
this species numerous on bedrock, rubble, and coarse gravel
(212 to 261 per sq. m.) and rare on coarse sand substrate.
The pollution tolerance of S. rubrum seems to be similar to
S. pulchellum. Bell and Nebeker (1969) found this species
moderately tolerant of low pH with a mean 96-hour TLM
of pH 3.32.
Specimens Examined: ILLINOIS — Middle Fork Vermil-
ion River, Penfield, 13X65, 1 nymph (Anderson). INDI-
ANA — Big Walnut Creek, Greencastle, 6VIII69, 1 nymph
(Lewis). MICHIGAN — Pere Marquette River, Lake Co.,
2VII47, 1 male (Leonard). MINNESOTA — Blackhoof
River Carlton Co., 2X164, 1 nymph (Bell). NORTH
CAROLINA —Big Alamance Creek, Toms Place, 5IV30,
1 male (reared) (Holotype of S. varium) (Traver); Cara-
way Creek, Sophia, 17IV30, 1 male, 1 female (reared)
(Paratypes of S. varium) (Traver). WISCONSIN—Oconto
River, Oconto Co., 28V69, 1 nymph (Hilsenhoff); Rocky
Creek, Wood Co., 5VIII68, 1 nymph (Hilsenhoff); Macan
River, Waushara Co., 71V72, 1 male (reared) (Flowers).
CANADA—Go-Home-Bay, Ontario, 19VI32, 1 male (Wai-
ley); Gatineau Lake, Wakefield, Quebec, 13VI30, 1 male
(reared) (McDunnough); Ottawa Golf Club, Quebec,
31VII24, 1 male (Holotype) (Walley).
DISCUSSION
Although adults of this species are very similar to 5. pul-
chellum, the nymphs are easily separated as discussed under
that species.
Synonymization of S. varium with this species resulted
from a comparison of the type series of both species. Al-
though the genitalia of the type of S. varium were missing,
I have examined the genitalia of other specimens from the
southeast and found them to be similar to S. rubrum. The
fore tarsal ratio averages slightly greater and the cross veins
are usually less crowded in S. varium than in S. rubrum,
but these characters are not sufficiently constant to justify
speciation. Nymphs from the 2 populations differ only in
intensity of dark coloration and cannot usually be separated.
Stenonema smithae Traver
(Figures 31, 52, 73, 106, 146, 159, 179)
Stenonema smithae Traver, 1937: 77; Berner, 1950: 59
NYMPH (Fig. 31): Length 7-9 mm.
Head: Dark brown, frontal portion thickly freckled with
small pale dots, area lateral to compound eyes pale, 3 pale
spots on vertex near ocelli; maxilla with 4-6 pectinate spines
and 30-40 setae on crown, 20-30 lateral setae (Fig. 73);
mandibles each with 7-8 teeth on inner margin of outer
canine (Fig. 106).
Thorax: Dark red-brown, a few pale markings on prono-
tum, median pale line on mesonotum; legs dark brown,
irregular pale blotches forming bands across each femur,
claws pectinate.
Abdomen: Mostly dark brown; terga 1-5 pale laterally, large
submedian pale spots on tergum 7; sterna 1-8 pale often
with dark bars and dots, sternum 9 with brown streaks
along lateral margins, a faint median dot at anterior mar-
gin and transverse dashes extending from this dot (Fig. 52);
gills 1-6 truncate at apices, 7th gill with fringe of hairs but
without tracheae; posterolateral angles of segments 7-9 ex-
tended as spines; caudal filaments brown at base becoming
yellow with brown joints near middle, apically with 3 dark
segments alternating with 1 pale segment.
MALE IMAGO: Length 7-8 mm.
Head: White, a faint transverse band across median carina.
Thorax: Flesh colored or yellowish white; mesoscutellum
white: legs yellow, each femur with dark apical and median
bands; fore tarsal ratio 1.7-2.1; fore wing hyaline, veins
dark brown, cross veins in bulla region only slightly crowded;
hind wing with apical margin very narrowly dusky (Fig. 159).
Abdomen: Pale yellowish; terga with dark spiracular dots
and black posterior margin on each (Fig. 146); genitalia
with small apical spine and minute terminal spine on each
penis lobe (Fig. 179); caudal filaments white, alternating
joints darkened.
ECOLOGY AND DISTRIBUTION
Berner (1950) made a thorough study of the life history
and ecology of the species in Florida. He found nymphs in
all types of permanent streams of the Coastal Plain of
northern Florida. He recently found nymphs on rocks along
the shore of highly eutrophic Lake Okeechobee (personal
communication). They were found in water with pH rang-
ing from less than 4 to 7.8 and temperatures up to 30°C.
This would put 5. smithae in the facultative group of in-
sects; however, Beck (1954) considered the species to be a
clean-water form.
Specimens Examined: ALABAMA—Tuscaloosa, 1VII36,
1 male (Holotype), 2 males (Paratypes) (Traver). FLOR-
IDA—Comfort Creek, Quincy, 1X67, 2 males (Peters,
34
-------
Tsui, and Jones); same location, 10VIII67, 2 males, 2 fe-
males (Cooper, Jones and Owens); Flat Creek, Chatta-
hoochee, 24VII67, 1 nymph (Cooper and Jones). MAINE
— Crooked River, Harrison, 14VII71, 3 males (Lewis).
DISCUSSION
This species is very close to S. rubromaculatum, but dif-
ferences in the genitalia of the male and the arrangement
of spines and setae on the nymphal maxillae will separate
the 2 species. All published records for S. stnithae are for
Alabama and Florida, and until recently, it has been con-
sidered the only species of Stenonema restricted to the
southern United States (Fig. 197). However, this distinction
is now questioned because of three males I collected in July
1971, at Harrison, Maine, which fit the description of this
species, and because of a report that the species may inhabit
Pennsylvania (J. Richardson — personal communication). It
is hoped that this question can be answered by rearing
nymphs from the Crooked River, Maine.
Stenonema terminatum (Walsh)
(Figures 21, 48, 62, 89, 116, 173)
Palingenia terminate Walsh, 1862: 376; 1863: 203
Stenonema terminatum Traver, 1935: 331; Burks, 1953: 175
NYMPH: Length 9-10 mm.
Head: Dark brown with many freckle-like dots, brown
band separating 2 large pale spots lateral to each compound
eye, pale spot near each ocellus and on vertex at posterior
margin; maxilla with 4-6 strongly pectinate spines but with-
out setae on crown, 15-25 lateral setae (Fig. 62); mandi-
bles each with 5-7 teeth on inner margin of outer canine
(Fig. 89).
Thorax: Brown with many small pale spots mostly clustered
on meson; legs about equally white and brown, anterior
margins hairy; each femur with 2 irregular brown bands
alternating with 3 white bands dorsally, reddish-brown near
apex; claws not pectinate (Fig. 116).
Abdomen: Brown with pale dots (Fig. 21); terga 1 and 2
mostly pale, tergum 9 with large pale median spot; sterna
2-9 usually with paired submedian posteriorly-diverging
dashes becoming larger and darker on more posterior seg-
ments (Fig. 48), sternum 9 (often 8 also) with brown shad-
ing around posterior and lateral margins; gills 1-6 truncate
at apices; 7th gill with fringe of hairs but without tracheae;
posterolateral angles of segments 7-9 extended as spines;
caudal filaments pale near bases, usually becoming banded
alternately light and dark beyond middle.
MALE IMAGO: See Burks (1953) for complete descrip-
tion.
Genitalia illustrated in Fig. 173.
ECOLOGY AND DISTRIBUTION
Nymphs of 5. terminatum inhabit coarse sand and gravel
substrates in larger streams of the north central states (Fig.
200). They were abundant in the Scioto River at Portsmouth,
Ohio, during the summer of 1969, and appeared unaffected
by the polluted conditions that existed at the time (Lewis,
1973). Two male images and 2 nymphs from western Can-
ada, very similar to S. terminatum, are tentatively placed
here, although they may represent a new species.1
Specimens Examined: ILLINOIS — Rock River, Rock-
ford, 41X40, 1 male (Burks); same location, 22V41, 1 male
(Ross and Burks); Rock Island, no date, 1 male, 1 female
(Types) (Walsh). INDIANA — Moots Creek, Ash Grove,
5VIII69, 1 male, 3 females (Lewis); Wildcat Creek, Pry-
]A new species closely related to S. terminatum is being described by
Jensen and Edmunds (personal communication).
mont, 4VIII69, 1 male, 1 female (subimagos) (Lewis).
OHIO—Ohio River, Portsmouth, 121X68, 2 nymphs (Lewis),
Ohio River, Cincinnati, 22VIII70, 1 male (reared) (Lewis);
Scioto River, Portsmouth, 6V70, 1 nymph (Lewis); same
location, 5V70, 7 males (reared), 14 females (reared), 25
nymphs (Lewis); same location, 121X68, 1 male, 1 nymph
(Lewis). CANADA—Aweme, Manitoba, 11VI23, 1 male
(Homotype) (White); Okanagan Landing, British Colum-
bia, 2VII34, 2 nymphs (Gartrell); Summerland, British
Columbia, 8VII33, 1 male (Gartrell).
DISCUSSION
The identity of the nymph of S. terminatum, described
by Lewis (1973), was established by rearing 5 males and
20 females from the Scioto River, Portsmouth, Ohio. These
adults were compared with the holotype from Illinois. Both
imagos and nymphs superficially resemble 5. ares, and the
adults could easily be confused with S. bipunctatum and
S. integrum, all of which occur in the type locality. Char-
acters used in the key of this manual have proven adequate
to separate both mature nymphs and male imagos of these
closely related species.
Burks (1953) synonymized S. placitum (Banks) with 5.
terminatum, but a careful examination of the genitalia of
the types has revealed important differences in the 2 species
resulting in resurrection of S. placitum.
Stenonema tripunctatum (Banks)
(Figures 19, 39, 61, 88, 127, 151, 154, 155, 171)
Heptagenia tripunctata Banks, 1910: 199
Stenonema tripunctatum Traver, 1935: 332; Burks, 1953:
168
Stenonema scitulum Traver, 1935: 330
Stenonema femoratum tripunctatum Spieth, 1947: 99
Stenonema femoratum scitulum Spieth, 1947: 100 NEW
COMBINATION
NYMPH (Fig. 19): Length 8-12 mm.
Head: Ground color tan or light brown freckled with pale
dots, anterior margin usually with a median and a pair of
sublateral pale spots; maxilla with 3-5 pectinate spines and
10-30 setae on crown, 20-40 lateral setae (Fig. 61), man-
dibles each with 5-8 teeth on inner margin of outer canine
(Fig. 88).
Thorax: Brown with a few pale dots, area lateral to com-
pound eyes usually mostly pale; legs brown with large ir-
regular white areas on dorsum of femora, basal and median
brown bands on tibiae, claws pectinate.
Abdomen: Brown usually distinctively marked with white
or yellow; terga 1 and 5 have pale "X-shaped" spots nearly
covering median area, a larger "X-shaped" spot covers terga
8 and 9; sterna 2-8 usually with a pair of sublateral brown
spots, sternum 9 with 2 pairs of brown spots laterally and a
pair of much larger brown spots at posterolateral angles
(Fig. 39); gills 1-6 rounded at apices, 7th gill with tracheae
and fringed with hairs; posterolateral angles of segments 3-9
extended as large spines; caudal filaments yellow at bases,
alternating pairs of light and dark segments in middle and
apical areas.
MALE IMAGO (Fig. 127): See Burks (1953) for de-
tailed description. Traver (1935) gives a good description
of S. tripunctatum scitulum.
Fore wing hyaline, stigmatic area shaded with brown, cross
veins crowded in bulla region (Fig. 154); hind wing either
with dark apical margin as in Fig. 151 (5. t. scitulum) or
without dark apical margin as in Fig. 155 (S. t. tripuncta-
tum); genitalia as in Fig. 171.
35
-------
ECOLOGY AND DISTRIBUTION
This species is common in lakes and pools of streams
over much of the United States (Fig. 202). It has been
reported from Canada to Texas and from New York to
Oregon. However, the Oregon record has been questioned
by Allen and Edmunds (1956). Most specimens from Ar-
kansas and Oklahoma labeled S. tripunctatum that I have
examined were the subspecies sciti/lum, which indicates that
this subspecies is more common than published reports indi-
cate. The nymph of this species was by far the most common
mayfly in Shayler Run, a small hard water stream near Cin-
cinnati, Ohio, receiving effluent from a sewage treatment plant
and containing high concentrations of TDP (1.5 mg/1 mean
yearly average) and TDS (450 mg/1 mean yearly average).
Other streams from which this species was collected ex-
hibited pH ranging between 7.5-8.0 and TDS ranging from
250-500 mg/1. However, in all cases the DO levels (> 6.0
mg/1) and temperatures (<25.0°C) were not limiting
(Nebeker and Lemke, 1968).
Specimens Examined: Stenonema tripunctatum tripunc-
tatum: KENTUCKY — Boiling Spring Creek, Munford-
ville, 8VIII69, 2 nymphs (Lewis); Paint Lick Creek, Kirks-
ville, 15VIII69, 2 nymphs (Lewis); W. Fork Drakes Creek,
Franklin, 25V71, 3 females (reared), 1 male (Myers).
MINNESOTA — Pine River, Pine River, 18VIII35, 1 fe-
male (Daggy). MISSOURI — Roaring River, Roaring River
State Park, 8VII57, 1 nymph (Peters). NEW YORK —
Westerfleld, 13VI05, 1 male (Type) (Banks). OHIO—Kain
Run, Williamsburg, 27V71, 1 female, 1 nymph (Lewis);
Little Miami River, Newtown, 18V68, 1 female (Lewis);
Ohio River, Cincinnati, 7VIII68, 1 nymph (Lewis); Shayler
Run, Union Township, 28V69, 1 male (Mason); same loca-
tion, 23IV71, 1 male (reared) (Lewis); Stillwater River,
Beamsville, 171X69, 1 nymph (Lewis). OKLAHOMA —
Comanche Co., 28II32, 1 male, 1 female, 1 nymph (Holo-
type and Paratypes of S. birdi) (Bird); Spavinaw Creek,
Spavinaw, 11VII57, 1 nymph (Peters). WISCONSIN —
Milwaukee, 22VII09, 1 male (Type) (Banks). CANADA
— Lake Winnipeg, Manitoba, 15X69, 1 nymph (Flannagan);
Knowlton Creek, Knowlton, Quebec, 111X30, 1 female
(Milne).
Stenonema tripunctatum scitidum: ARKANSAS—Wash-
ington Co., 15IV56, 1 male (Peters); Cove Creek, Wash-
ington Co., 22V62, 1 male (Kite). KENTUCKY—Boiling
Spring Creek, Munfordville, 8VIII69, 1 male (reared)
(Lewis); Paint Lick Creek, Kirksville, 15VIII69, 1 male
(reared) (Lewis); W. Fork Drakes Creek, Franklin, 24VIII71,
1 male (Myers). OHIO —Kain Run, Williamsburg, 18V71,
2 males (Lewis); same location 27V71, 1 male (reared), 4
females (reared) (Lewis); Shayler Run, Union Township,
7VI69, 2 males (reared), 3 females (reared) (Mason);
same location, 13VI69, 1 female (Lewis); same location,
4XII69, 1 nymph (Mason); same location, 14IV71, 1 male
(reared) (Lewis); same location, 23IV71, 1 male (reared),
1 nymph (Lewis). OKLAHOMA — Fourche Maline River,
Wilburton, 1VII69, 7 nymphs (Prins); Mountain Fork
River, Hochatown, 6V39, 1 male (Waddle); Latimer Co.,
20VI31, 1 male (Holotype), 1 female (Paratype) (Bird);
Salina Creek, Locust Grove, 12VI57, 1 male (Peters);
Spavinaw Creek, Spavinaw, 11VI57, 1 female (Peters).
DISCUSSION
This species consists of 2 subspecies S. tripunctatum tri-
punctatum and S. tripunctatum scitnliim. In the Ohio River
Basin, both subspecies occur in the same streams and inter-
grades are the rule rather than the exception. Sympatry,
however, occurs with S. femoratitm as discussed under that
species. Of 42 FEMORATUM group nymphs from Shayler
Run near Cincinnati, Ohio, reared to adults, 19 were S.
tripunctatum scitidum, 6 were S. tripunctatum tripunctatum,
6 were S. femoratum, and 11 were 5. tripunctatum x scitu-
lum hybrids possessing intermediate characters. The holo-
types of the 2 subspecies differ only in size and amount of
dark shading in the apical areas of the hind wings. Where
the 2 forms occur together, none of these characters are
constant. The nymph of 5. tripunctatum scitulttm (recently
described in The Proceedings of the First International Con-
ference on Ephemeroptera [Lewis, 1973]) differs only
slightly from typical 5. tripunctatum tripunctatum nymphs.
Daggy (1941) suspected that 5. scitulum was not distinct
from 5. tripunctatum. Spieth (1947) considered both S.
scitidum and 5. tripunctatum to be subspecies of S. femora-
tum, and suggested that S. tripunctatum derived from 5.
scitidum, which moved into the Ohio River Basin from the
southwest following the last glaciation. Stenonema femora-
turn is a monotypic species; therefore, 5. scitulum becomes 5.
tripunctatum scitulum.
Stenonema vicarium (Walker)
(Figures 28, 47, 72, 105, 109, 135, 163)
Baetis vicaria Walker, 1853: 565
Stenonema vicarium Traver, 1935: 334; Burks, 1953: 172
NYMPH (Fig. 28): Length 14-18 mm.
Head: Brown freckled with pale dots, area lateral to com-
pound eyes and at posterior margin pale; maxilla with 2-4
pectinate spines and 10-30 setae on crown, 15-30 lateral
setae (Fig. 72); mandibles each with 7-8 teeth on inner
margin of outer canine (Fig. 105).
Thorax: Uniform brown except for large pale spots at lat-
eral and anterior margins of pronotum; legs pale with ir-
regular brown bands on dorsum of femora, claws not pecti-
nate (Fig. 109).
Abdomen: With brown mid-dorsal band length of abdomen;
terga 1-10 with broad brown crossband at posterior mar-
gins, terga 5 and 6 often almost completely brown, others
usually with elongate submedian pale spots; sterna white
with broad dark brown crossbands at posterior margins,
usually apical half or more of sternum 9 brown (Fig. 47);
gills 1-6 truncate at apices, 7th gill with fringe of hairs but
without tracheae; posterolateral angles of segments 3-9 ex-
tended as spines; caudal filaments tan or yellow in "basal
half, usually dark and light pairs of segments alternating
apically.
MALE IMAGO (Fig. 135): See Traver (1935) or Burks
(1953) for complete description.
Fore wing hyaline, stigmatic area shaded with red, cross
veins moderately crowded in bulla region (Fig. 163); geni-
talia with large apical spine and small subterminal spine on
each penis lobe.
ECOLOGY AND DISTRIBUTION
This species is common in most of the eastern United
States south to North Carolina, Kentucky, and Illinois, and
in eastern and central Canada (Fig. 203). Nymphs inhabit
moderate to fast rivers and streams that are not polluted by
domestic wastes; however, Leonard (1965) found them in
streams polluted by.toxic substances. It is the most common
species in the small mountain streams of West Virginia.
Specimens Examined: NEW YORK — Sacandaga River,
Sport Island, 12VI09, 1 male, 1 female. OHIO — Mad
River, West Liberty, 171X69, 1 nymph (Lewis); Turkey
Run Creek, Friendship, 6X69, 1 nymph (Lewis). PENN-
SYLVANIA—Allegheny River, Coudersport, 24VII69, 1
nymph (Lewis). VERMONT — N. Branch Bridgewater
Creek, Bridgewater, 5X63, 1 nymph (Whitney); Potash
36
-------
Brook, S. Burlington. 12X60, 2 nymphs (Cochran). WEST
VIRGINIA — Glady Fork, Glady, 20VII69, 1 nymph
(Lewis). CANADA—Stream 40 mi. SE of Kenora, On-
tario, 14VI69, 1 male (reared) (Flannagan).
DISCUSSION
Both the nymphs and adults of 5. vicarium are distinctive
and not likely to be confused with other species except
S. fusciiin, to which it is closely related. Characters used
in the keys of this manual will separate most specimens.
Burks (1953) synonymized 5. rivnlicolnm (McDun-
nough) with S. vicarium. His figures 344 and 346 should be
reversed. Figure 346 is the genitalia of S. vicarium. There
is little doubt that S. rivnlicolnm is intermediate between
5. vicarium and jnscnm, but it is herein transferred to S. fus-
cnm for reasons given under that species.
REFERENCES
Allen, Richard K., and George F. Edmunds, Jr. (1956). A
list of the mayflies of Oregon. Utah Acad. Sci. Proc.
33:85-87.
Banks, Nathan (1910). Notes on our eastern species of the
mayfly genus Hcptagenia. Can. Ent. 42:197-202.
(1914). New neuropteroid insects, native
and exotic. Acad. Nat. Sci. Phila. Proc. 66:608-632.
Beck, William M., Jr. (1954). Studies in stream pollution
biology. I. A simplified ecological classification of organ-
isms. Quart. Jour. Fla. Acad. Sci. 17(4) :211-227.
(1969). Stream monitoring biological para-
meters. Florida's Environmental Engineering Conference
on Water Pollution Control. Fla. Eng. Ind. Exp. Stat.,
Bull. Ser. 135:1-168.
(1973). Chemical and physical aspects of
the Blackwater River in northwestern Florida. In Pro-
ceedings of the First International Conference on Ephe-
meroptera. E. J. Brill, Leiden, Netherlands, pp. 231-241.
Bell, Henry L. (1969). Effect of substrate types on aquatic
insect distribution. Jour. Minn. Acad. Sci. 35(2/3) :79-81.
, and Alan V. Nebeker (1969). Preliminary
studies on the tolerance of aquatic insects to low pH.
Jour. Kansas Ent. Soc. 42(2) :230-236.
Bender, Michael E., and Paul Eisele (1971). Long term
effects of pesticides on stream invertebrates. Project com-
pletion report to Office of Water Resources Research,
OWRR Project Number A-029-MICH, Univ. Michigan,
Ann Arbor.
Berner, Lewis (1950). The mayflies of Florida. Univ. Fla.
Studies Biol. Sci. Ser. 4:1-265.
Bick, G. H., L. E. Hornuff, and E. N. Lambremont (1953).
An ecological reconnaissance of a naturally acid stream
in southern Louisiana. Jour. Tenn. Acad. Sci. 28(3):
221-230.
Burks, B. D. (1946). New Heptagenine mayflies. Ann. Ent.
Soc. 39:607-615.
(1953). The mayflies, or Ephemeroptera, of
Illinois. 111. Nat. Hist. Survey Bull. 26:1-216.
Cairns, John Jr., K. L. Dickson, and G. Lanza (1973).
Rapid biological monitoring system for determining
aquatic community structure in receiving systems. Bio-
logical Methods for the Assessment of Water Quality.
ASTM STP 528. American Society for Testing and Ma-
terials, pp. 148-163.
Chutter, F. M. (1972). An empirical biotic index of the
quality of water in South African streams and rivers.
Water Res. 6:19-30.
Clemens, W. A. (1913). New species and new life histories
of Ephemeridae or mayflies. Can. Ent. 45:246-262, 329-
341.
, and A. K. Leonard (1924). On two species
of mayflies of the genus Heptagenia. Can. Ent. 56:17-18.
Daggy, Richard H. (1941). Taxonomy of Minnesota may-
flies. Master's Thesis, Division of Entomology and Eco-
nomic Zoology, University of Minnesota. St. Paul. Un-
published.
(1945). New species and previously unde-
scribed naiads of some Minnesota mayflies (Ephemerop-
tera). Ann. Ent. Soc. Am. 38:373-396.
Edmunds, George F. (1962). The type localities of the
Ephemeroptera of North America north of Mexico. Univ.
Utah Biol. Ser. 2(5): 1-45.
Gaufin, A. R. (1958). The effects of pollution on a mid-
western stream. Ohio Jour. Sci. 58:197-208.
, and C. M. Tarzwell (1952). Aquatic in-
vertebrates as indicators of stream pollution. Pub. Health
Rept. 67(l):57-64.
Hagen, Herman (1861). Synopsis of Neuroptera of North
America, with a list of South American species. Smith-
sonian Inst. Misc. Collect. 4:33-55.
Ide, F. P. (1930). Contributions to the biology of Ontario
mayflies with descriptions of new species. Can. Ent.
62:204-213, 218-231.
(1935) Post embryological development of
Ephemeroptera (Mayflies). External characters only. Can.
Jour. Res. 12:433-478.
Koss, Richard W. (1968). Morphology and taxonomic use
of Ephemeroptera eggs. Ann. Ent. Soc. Am. 61(3):696-
721.
Krueger, Arvin Herman (1969). Ephemeroptera nymphs of
Wisconsin (a preliminary survey). Master's Thesis, De-
partment of Entomology, University of Wisconsin, Madi-
son.
Leonard, Justin W. (1965) Environmental requirements of
Ephemeroptera. In Biological problems in water pollu-
tion, third seminar, 1962. PHS Pub. No. 999-WP-25:
U.S., DHEW, Cincinnati, OH pp. 110-117.
, and Fannie A. Leonard (1962). Mayflies of
Michigan Trout Streams. Cranbrook Institute of Science,
Bloomfield Hills, Mich.
Lewis, P. A. (1973). Description and ecology of three
Stenonema mayfly nymphs. Proceedings of the First In-
ternational Conference on Ephemeroptera. E. J. Brill,
Leiden, Netherlands, pp. 64-72.
(1974). Three new Stenonema species from
Eastern North America (Ephemeroptera:Heptageniidae).
Proc. Ent. Soc. Washington. 76(3) :347-355.
Mason, William T., J. B. Anderson, and George E. Morri-
son (1967). A limestone-filled, artificial substrate sam-
pler-float unit for collecting macroinvertebrates in large
streams. Prog. Fish. Cult. 29(2) :74.
, and Philip A. Lewis (1970). Rearing devices
for stream insects. Prog. Fish. Cult. 32(l):61-62.
-, P. A. Lewis, and J. B. Anderson (1971).
Macroinvertebrate monitoring in the Ohio River Basin
1963-1967. Cooperative report by: Office of Technical
Programs, Ohio Basin Region, and Analytical Quality
Control Laboratory, U.S. EPA, Cincinnati, Ohio.
McDunnough, J. (1924). New Ephemeridae from Illinois.
Can. Ent. 56:7-9.
37
-------
McDunnough, J. (1925a). New Ephemeroptera of Covey
Hill. Que. Royal Soc. Can. Trans. 19:207-224.
(1925b). New Canadian Ephemeridae with
notes, III. Can. Ent. 57:168-176, 185-192.
(1926). Notes on North American Ephe-
meroptera with descriptions of new species. Can. Ent.
58:184-196.
(1930). The Ephemeroptera of the north
shore of the Gulf of St. Lawrence. Can. Ent. 62:54-62.
(1933). Notes on the Heptagenine species
described by Clemens from the Georgian Bay Region,
Ont. (Ephemeroptera). Can. Ent. 65:16-24, 33-43.
Muller-Liebenau, Ingrid (1969). Revision der Europaisch-
ean Arten dar Gattung, Baelis Leach, 1815 (Insecta,
Ephemeroptera). Gewasser und Abwasser 48 & 49:5-214.
Nebeker, A. C., and A. E. Lemke (1968). Preliminary
studies on the tolerance of aquatic insects to heated wat-
ers. Jour. Kansas Ent. Soc. 41(3):413-418.
Needham, J. G. (1901). Aquatic insects in the Adirondacks
(Ephemeridae section). N.Y. State Mus. Bull. No. 47:
418-429.
(1905). Mayflies and midges of New York.
N.Y. State Mus. Bull. No. 86:17-62, 316-327.
Jay R. Traver, and Yin-Chi Hsu (1935).
The Biology of Mayflies. Comstock Publishing Co., Ith-
aca, N.Y.
Neel, J. K. (1968). Seasonal succession of benthic algae and
their macroinvertebrate residents in a head-water lime-
stone stream. Jour. Water Poll. Cont. Fed. 40(2)Part
2:R10-R30.
Parsons, J. D. (1968). The effects of acid strip-mine efflu-
ents on the ecology of a stream. Arch. Hydrobiol. 65 (1):
25-50.
Peters, Williams L., and George F. Edmunds, Jr. (1970).
Revision of the generic classification of Eastern Hemis-
phere Letophlebiidae. Pacific Insects 12(1): 157-240.
Say, Thomas (1823). Descriptions of insects belonging to
the order Neuroptera Linn, Latr. collected by the expedi-
tion authorized by J. C. Calhoun, Secretary of War, under
the command of Major S. H. Long. Western Quart. Re-
porter (Cincinnati). 2(2): 160-165.
(1839). Descriptions of new North Ameri-
can Neuropterous insects and observation on some al-
ready described. Acad. Nat. Sci. Phila. Jour. 8:9-46.
Spieth, Herman T. (1938). Studies on the biology of the
Ephemeroptera I. Coloration and its relation to seasonal
emergence. Can. Ent. 70:210-218.
(1947). Taxonomic studies on the Ephe-
meroptera IV. The genus Stenonema. Ann. Ent. Soc.
Am. 40:87-122.
Simmons, George M., and Avis Winfleld (1971). A feasi-
bility study using conservation webbing as an artificial
substrate in macrobenthic studies. Va. Jour. Sci. 22(2):
52-59.
Surber, F. W. (1936). Rainbow trout and bottom fauna
production in one mile of stream. Trans. Am. Fisheries
Soc. 66:193-202.
Traver, Jay R. (1933a). Mayflies of North Carolina. Part
III. The Heptageninae. Jour. Elisha Mitchell Sci. Soc.
48:141-207.
(1933b). Heptagenine mayflies of North
America. Jour. N.Y. Ent. Soc. 41:105-125.
(1935). Heptagenine section in The Biology
of Mayflies. Comstock Publishing Co., Ithaca, N.Y., pp.
293-426.
(1937). Notes on mayflies of the southeast-
ern states. Jour. Elisha Mitchell Sci. Soc. 53(l):27-86.
-, and George F. Edmunds (1968). A revision
of the Baetidae with spatulate clawed nymphs (Ephe-
meroptera). Pacific Insects 10(3-4):629-677.
Walker, Francis (1853). Catalogue of the Specimens of
Neuropterous Insects in the Collection of the British
Museum, Part III pp. 477-585.
Walsh, Benjamin D. (1862). List of the Pseudoneuroptera
of Illinois contained in the cabinet of the writer, with
descriptions of over forty new species, and notes on their
structural affinities. Acad. Nat. Sci. Phila. Proc. 13:361-
402.
38
-------
APPENDIX A —
Plate I — Figs. 8-13 GUIs of the three groups of
nymphs.
8, 5. gildersleevei Kirtland, OH (SOX) Fourth gill.
9, S. gildersleevei Kirtland, OH (75X) Seventh gill.
10, S.femoratum Batavia, OH (SOX) Fourth gill.
11, S.femoratum Batavia, OH (75X) Seventh gill.
12, 5. pulchellum Cincinnati, OH (75X) Fourth gill.
13, S. pulchellum Cincinnati, OH (SOX) Seventh gill.
Plate II — Figs. 14-19 Dorsal maculation of
nymphs.
14, S. interpunctatum Jerome, IN (10X). 15, S. can-
didum Paratype (20X). 16, 5. gildersleevei Topotype
(6X). 17, 5. Carolina Jerome, IN (8X). 18, S. femo-
ratum Batavia, OH (8X). 19, 5. tripunctatum Ba-
tavia, OH (8X).
Plate III — Figs. 20-26 Dorsal maculation of
nymphs.
20, S. luteitm Embarrass R., WI (10X) Identified
by Dr. Ide. 21,5. termination Portsmouth, OH (6X).
22, S. mediopunctatum Apple R., WI (10X) Identi-
fied by Dr. Ide. 23, S. exiguwn FL (4X) Note pale
band across mesonotum at base of wing pads. 24,
S. quinquespinum Cincinnati, OH (15X) Note pale
seventh tergum. 25, S. integrum Madison, IN (4X)
Note large white V-shaped patch on terga 7-9. 26,
S. pudicum Avondale, PA (10X).
Plate IV — Figs. 27-34 Dorsal maculation of
nymphs.
27, S. ithaca Chicago, NY (8X). 28, 5. vicarium
Honors, MI (3X). 29, S. fuscum New Brunswick
Province, CANADA (4X). 30, S. rubromaculatum
Glady, WV (4X). 31,5. smithae Avondale, PA (4X).
32, S. rubrum (Paratype of S. varium) (5X). 33, S.
bipunctatum Clam R., WI (6X). 34, S. luteum Topo-
type (8X).
Plate V — Figs. 35-39 Ventral maculation of
nymphs.
35, S. interpunctatum s.s. Noblesville, IN (8X). 36,
S. interpunctatum jrontale Harrison, ME (4X). 37,
S. integrum Madison, IN (8X). 38, S. jemoratum
Batavia, OH (6X). 39, S. tripunctatum Batavia, OH
(4X).
Plate VI — Figs. 40-47 Ventral maculation of
nymphs.
40, S. rubromaculatum Millport, PA (10X) Note
black band near middle of sterna. 41,5. ithaca Bing-
PHOTOGRAPHS
hamton, NY (8X) Note marks on sternum 9. 42,
5. nepotellum Omar, IN (10X). 43, 5. pudicum
Avondale, PA (13X). 44, 5. mediopunctatum Apple
R., WI (4X). 45, 5. luteum Topotype (13X) Note
black posterior band on sternum 8. 46, 5. fuscum
Baptism R., WI (13X) Note black spots at postero-
lateral angles of sternum 9. 47, S. vicarium Honors,
MI (6X) Note continuous band across posterior half
of sternum 9.
Plate VII — Figs. 48-52 Ventral maculation of
nymphs.
48, 5. terminatum Portsmouth, OH (5X). 49, 5. pul-
chellum Markle, IN (6X). 50, 5. quinquespinum Cin-
cinnati, OH (5X). 51, S. rubrum (Paratype of S.
varium) (10X) 52, 5. smithae Chattahooche, FL
(13X).
Plate VIII — Figs. 53-61 Maxillae (Ventral view).
53, Heptagenia sp. Cincinnati, OH (100X) Note lat-
eral setae scattered over surface of galea. 54, 5. Caro-
lina Quebec Province, CANADA (125X) Identified
by McDunnough. 55, 5. candidum Franklin, KY
(75X). 56, 5. interpunctatum Spring Grove, IL
(100X). 57, S.pallidum Holotype (125X) Arrow
indicates pectinate spines on crown. 58, 5. jemora-
tum Williamsburg, OH (200X) Arrow indicates setae
on crown. 59, 5. gildersleevei Walden Ridge, TN
(200X). 60, 5. minnetonka Williamsburg, OH
(125X). 61, 5. tripunctatum Providence, KY (200X).
Plate IX — Figs. 62-69 Maxillae (Ventral view).
62, 5. terminatum Cincinnati, OH (200X) Note
spines only slightly pectinate. 63, 5. exiguum Madi-
son, IN (125X). 64, 5. carlsoni Pine Mt., KY (100X).
65, 5. quinquespinum Clam R., WI (125X). 66, 5.
pulchellum Cincinnati, OH (200X) Arrow indicates
lateral setae. 67, 5. ithaca Binghamton, NY (125X).
68, 5. nepotellum Topotype (100X). 69, 5. ares
Greenville, IL (125X).
Plate X — Figs. 70-78 Maxillae (Ventral view).
70, 5. integrum Cincinnati, OH (400X). 71, 5. pudi-
cum Avondale, PA (75X). 72, 5. vicarium West
Liberty, OH (125X). 73, 5. smithae Chattahoochee,
FL (125X). 74, S. rubrum Popple R., WI (125X).
75, 5. fuscum Otter Creek, WI (100 X). 76, 5. rub-
romaculatum Topotype (125X) Identified by Mc-
Dunnough. 77, 5. luteum Ontario Province, CAN-
ADA (125X). 78, S. mediopunctatum Barren, WI
(125X).
39
-------
Plate XI — Figs. 79-88 Mandibles (Ventral view of
left mandible except as noted).
79, Heptagenia sp. Cincinnati, OH (125X) Dorsal
view. Note more than one lacinia mobilis. 80, 5.
minnetonka Iron R., WI (325X) Ventral view of
right mandible. 81,5. gildersleevei Paratype (200X).
82, S. candidum Paratype (75X) Arrow denotes left
outer canine. 83, 5. pallidum Holotype (250X) Ar-
row denotes inner canine. 84, 5. Carolina Swannanoa,
NC (125X) Dorsal view. Note two blunt teeth on
inner margin of inner canine. 85, S. interpunctatum
s.s. (Holotype of 5. conjunctum) (200X) Dorsal view.
Arrow denotes lacinia mobilis. 86, 5. interpunctatum
canadense Honors, MI (200X). 87, 5. femoratum
Batavia, OH (250X) Dorsal view. 88, 5. tripuncta-
tum St. Leon, IN (125X).
Plate XII — Figs. 89-98 Mandibles (Ventral view
of left mandible except as noted).
89, S. terminatum British Columbia Province, CAN-
ADA (300X) Dorsal view. 90, S. bipunctatum Clam
R., WI (300X). 91, S. pulchellum Cincinnati, OH
(200X) Right mandible. Compare with left mandible
(Fig. 9,2). Note long spine at apex of inner canine
and absence of lacinia mobilis. 92, 5. pulchellum
Warsaw, KY (200X) Dorsal view. 93, S.ithaca
Binghamton, NY (125X) Dorsal view. 94, 5. exi-
guum Madison, IN (100X). 95, S. ares Wisconsin
R., WI (200X). 96, S. annexum Fear R., NC (200X)
Ventral view of right mandible. 97, S. integrum
Cincinnati OH (200X) Dorsal view. 98, 5. luteum
Ontario Province, CANADA (200X).
Plate XIII — Figs. 99-108 Mandibles (Ventral view
of left mandible except as noted).
99, 5. pudicum Avondale, PA (125X) Ventral view
of right mandible. 100, 5. rubrum Macan R., WI
(325X) Ventral view of right mandible. 101, 5. fus-
cum Averill Creek, WI (250X). 102, 5. mediopunc-
tatum Barren, WI (100X). 103, 5. rubromaculatum
Ontario Province, CANADA (125X) Dorsal view.
104, S. quinquespinum Williamsburg, OH (200X).
105, S. vicarium NY (200X) Dorsal view of right
mandible. 106, S. smithae Paratype (325X) Ventral
view of right mandible. 107, S. carlsoni Anderson
Co., SC (200X). 108, S. nepotellum Camp Creek,
WI (200X).
Plate XIV — Figs. 109-118 Claws of the nymphs.
109, S. vicarium Glady, WV (100X). 110, 5. an-
nexum Fear R., NC (250X) Arrow denotes pectina-
tions on claw. Ill, S. luteum Ontario Province,
CANADA (250X). 112, S. rubrum Macan R, WI
(325X). 113, S. rubromaculatum Ithaca (?), NY
(200X). 114, S. pulchellum Batavia, OH (200X).
115, S. ares Manitoba Province, CANADA (200X).
116, 5. terminatum Red Cedar R., WI (200X). 117,
5. exiguum FL (200X). 118, 5. pudicum Marvindale,
PA (125X).
Plate XV — Figs. 119-128 Maculation of male
imagos.
119, S. Carolina Pine Mountain State Park, KY (8X).
120, S. pallidum Holotype (7X). 121, S. candidum
Franklin, KY (8X). 122, 5. interpunctatum cana-
dense (Paratype of 5. areion) (6X) Arrow indicates
black posterior margin of tergum 5. 123, S. inter-
punctatum canadense Manitoba Province, CANADA
(75X) Note black shading in mid-dorsal area. 124,
S. interpunctatum cf. frontale Franklin, KY (7X).
125, S. interpunctatum canadense Manitoba Prov-
ince, CANADA (40X) Arrow indicates black line
on face below antenna. 126, 5. interpunctatum s.s.
Franklin, KY (7X). 127, S. tripunctatum Batavia,
OH (20X) Note three black marks at posterior mar-
gin of terga. 128, 5. femoratum Batavia, OH (30X).
Plate XVI — Figs. 129-137 Maculation of imagos
(Males except as noted).
129, S. ares Paratype (7X) Note pair of black dashes
at posterior margins of middle terga. 130, 5. carlsoni
Athens, GA (4X) Female. 131, S.ithaca Paratype
(40X). 132, S.fuscum (Paratype of S. rivulicolum)
(15X). 133, S. bipunctatum Holotype (10X) Note
pair of black dashes at posterior margin of tergum
6. 134, S. integrum var. metriotes Cincinnati, OH
(20X) Female. Note black median dashes at poster-
ior margins of middle terga. 135, 5. vicarium Dairy-
land, WI (25X) Note wide dark posterior margins
and median bands on terga. 136, S. pudicum Avon-
dale, PA (20X) Dorsal view. 137, 5. pudicum Avon-
dale, PA (20X) Lateral view.
Plate XVII — Figs. 138-147 Maculation of imagos
(Males except as noted).
138, S. quinquespinum Williamsburg, OH (10X)
Note narrow dark apical margin of hind wing and
absence of dark posterior margins on terga. 139,
S. integrum Cincinnati, OH (25X) Lateral view.
Note oblique spiracular streaks on terga. 140, S. in-
tegrum Cincinnati, OH (30X) Dorsal view of female.
Note longitudinal line in median area of tergum 6.
141, S. mediopunctatum Holotype (10X) Note black
median dash at posterior margin of each tergum.
142, S. luteum Lafayette Co., WI (30X) Arrow in-
dicates faint oblique spiracular streak. 143, S. pul-
chellum Batavia, OH (20X) Arrow indicates black
spiracular dot on tergum 5. 144, S. luteum Homo-
type from Ontario Province, CANADA (10X) De-
termined by McDunnough. 145, S. nepotellum
Franklin, KY (15X). 146, S. smithae Quincy, FL
(25X). 147, S. fuscum Richland Co., WI (30X) Ar-
row denotes dark median band on tergum 5.
40
-------
Plate XVIII — Figs. 148-155 Wings.
148, S. Carolina Wardensville, WV (12X) Fore wing.
Note thickened basal cross veins in radial space.
149, S. interpunctatum Spring Grove, IL (20X) Hind
wing. 150, S. interpunctatum Spring Grove, IL (12X)
Fore wing. Note black bar connecting two cross
veins below bulla. 151, S. tripunctatum scitulum Ba-
tavia, OH (7X) Note crowded cross veins in only
first three spaces in bulla area of fore wing and dark
apex of hind wing. 152, S. candidum Franklin, KY
(12X) Fore wing. Note reduction of cross veins in
bulla area. 153, S.femoratum Batavia, OH (7X)
Note crowded cross veins in first six spaces of fore
wing and wide dark apical band of hind wing. 154,
S. tripunctatum s.s. Batavia, OH (12X) Fore wing.
Note crowded cross veins in only first three spaces.
155, S. tripunctatum s.s. Loveland, OH (16X) Hind
wing. Note absence of dark apical band.
Plate XIX — Figs. 156-164 Wings.
156, S. pulchellum Cincinnati, OH (16X) Fore wing.
157, S. exiguum Topotype (40X) Hind wing. Note
faint dark shading at apex. 158. S. pudicum Avon-
dale, PA (7X) Note crowded cross veins in first six
spaces in bulla area of fore wing and dark apical
band of hind wings. 159, 5. smithae Avondale, PA
(10X). 160, 5. integrum Cincinnati, OH (16X) Fore
wing. Note elongate cells distal to bulla area set off
by cross veins that form irregular lines across wing.
161, S.ithaca Paratype (40X) Fore wing. 162, S.
nepotellum Franklin, KY (16X) Note slight crowd-
ing of cross veins in bulla area of fore wing. 163,
5. vicarium Dairyland, WI (8X) Note moderate
crowding of cross veins in bulla area of fore wing.
164, 5. rubrum Paratype (10X).
Plate XX — Figs. 165-172 Male genitalia (Dorsal
view).
165, S.pallidum Holotype (300X) Arrow denotes
subapical spine. 166, S.floridense Blackman, FL
(125X) Note large axial spines (Arrow). 167, 5.
candidum Franklin, KY (200X). 168, S. gilder-
sleevei Kirtland, OH (200X). 169, S. interpuncta-
tum canadense Ontario Province, CANADA (125X)
Arrow denotes lateral spines on right penis lobe.
170, S. Carolina Topotype (200X) Note very minute
lateral spines on penis lobe. 171, S. tripunctatum
Prairie Grove, AR (100X) Note straight apical mar-
gins. 172, S. femoratum Batavia, OH (125X).
Plate XXI — Figs. 173-180 Male genitalia (Dorsal
view).
173, S.terminatum Portsmouth, OH (200X). 174,
S. modestum Holotype (400X) Arrow indicates dis-
cal spine. 175, S. annexum Franklin, KY (125X)
Arrow indicates mesal spine. 176, S. quinquespinum
Williamsburg, OH (300X). 177, S. integrum Cin-
cinnati, OH (200X). 178, 5. pulchellum Batavia,
OH (325X). 179, S. smithae Paratype (325X). 180,
S. placitum Holotype (325X).
Plate XXII — Figs. 181-188 Male genitalia (Dorsal
view).
181,5. pudicum NC (200X). 182, S. ithaca Salmon
Creek, NY (325X). 183, 5. rubromaculatum On-
tario Province, CANADA (125X). 184, S.fuscum
Holotype (100X). 185, S. rubrum Paratype (400X).
186, S. nepotellum Topotype (125X). 187, S. bi-
punctatum Paratype (600X) Arrow indicates termi-
nal spine. 188, S.luteum Ontario Province, CAN-
ADA (300X) Arrow indicates apicomesal spine.
NOTE: Because the plates were reduced in size during
printing, the magnification factors given are approxi-
mately 28 percent greater than actual size. A2-cm scale
is provided on each plate to represent this reduction.
41
-------
2 cm
\ '•' /' -
•-•
13
PLATE 1 —FIGS. 8-13 GILLS OF THE THREE GROUPS OF NYMPHS
12
-------
>-4
Jf'
16
15
2 cm
17
PLATE II —FIGS. 14-19 DORSAL MACULATION OF NYMPHS
43
-------
2 cm
24
PLATE IH — KIGS. 20-26 DORSAL MACULATJON OF NYMPHS
•;
-------
ip^^^swiP
'
27%^
ipMMM
M
UA
351
ti»
* 21
29.
34
PLATE IV —FIGS. 27-34 DORSAL MACULATION OF NYMPHS
45
-------
PLATE V — FIGS. 35-39 VENTRAL MACULATION OF NYMPHS
46
-------
47
PLATE VI —FIGS. 40-47 VENTRAL MACULATION OF NYMPHS
47
-------
PLATE VII — FIGS. 48-52 VENTRAL MACULATION OF NYMPHS
48
-------
PLATE VIII — FIGS. 53-61 MAXILLAE (Ventral view)
49
-------
PLATE IX —FIGS. 62-69 MAXILLAE (Ventral view)
50
-------
•
I
» «• • • :
76
PLATE X —FIGS. 70-78 MAXILLAE (Ventral view)
51
-------
PLATE XI —FIGS. 79-88 MANDIBLES (Ventral view of left mandible except as noted)
52
-------
PLATE XII —FIGS. 89-98 MANDIBLES (Ventral view of left mandible except as noted)
-;
-------
PLATE XIII —FIGS. 99-108 MANDIBLES (Ventral view of left mandible except as noted)
54
-------
PLATE XIV —FIGS. 109-118 CLAWS OF THE NYMPHS
55
-------
PLATE XV —FIGS. 119-128 MACULATION OF MALE IMAGOS
56
-------
\*Bii^
2
^133
'3V-134
l35
PLATE XVI —FIGS. 129-137 MACULATION OF 1MAGOS (Males except as noted)
5-
-------
145
2 cm
PLATE XVII —FIGS. 138-147 MACULATION OF IMAGOS (Males except as noted)
58
-------
•:'"•'
54
155
PLATE XVIII —FIGS. 148-155 WINGS
59
-------
157
163
PLATE XIX —FIGS. 156-164 WINGS
60
-------
u t
9
2 cm
PLATE XX —FIGS. 165-172 MALE GENITALIA (Dorsal view)
61
-------
IT'
1 \i *•'-
• • *1
'
177
175
2 cm
* \
174 X
PLATE XXI —FIGS. 173-180 MALE GENITALIA (Dorsal view)
62
-------
PLATE XXII —FIGS. 181-188 MALE GENITALIA (Dorsal view)
63
-------
APPENDIX B — TABLES
TABLE 3. SUMMARY OF COLLECTIONS EXAMINED
Collections
Cornell
F. Myers
INHS2
Total
P. Lewis
J. Flannagan
Fla. A&M
INHS
U. of Wise.
Total
P. Lewis
I. Flannagan
Fla. A&M
CNC3
INHS
U. of Wise.
Total
P. Lewis
M. Anderson
J. Flannagan
INHS
F. Myers
Cornell
Fla. A&M
CNC
Total
INHS
Cornell
F. Myers
Total
Fla. A&M
Total
P. Lewis
INHS
Cornell
Fla. A&M
MCZ"
CNC
Total
Nymphs
1
1
4
1
1
3
9
2
9
11
10
1
1
12
1
1
2
1
I
1
1
Subimagos Images
Males Females Males
5. annexum
1
1
5
7
5. ares
7
7
S. bipunctatum
2 2
1
2
1
2 6
5. i. canadense
3 2 l
1 1
6
3
2 1 1
1
2
6 3 15
S. candidum
3
3
1
7
S. carlsoni
2
2
S. Carolina
1
3
1 1 9
2
1
3
i o rs
Tvoes
Females examined1
H
H
H.P.T
1
1 H, P, T
1
1
H
1
3 H
8
P of S. areion
2 A, P of S. ohioense
1
11
1 H, A, P
1 H, A, P
2 H
2 H
-
H
1 P
11
H, P
64
-------
TABLE 3. SUMMARY OF COLLECTIONS EXAMINED — Continued
Collections
P. Lewis
M. Anderson
Cornell
CNC
INKS
U. of Wise.
Total
P. Lewis
U. of Minn.
Cornell
INHS
Total
Fla. A&M
Total
P. Lewis
CNC
M. Anderson
J. Flannagan
INHS
Cornell
Fla. A&M
MCZ
Total
P. Lewis
F. Myers
MCZ
CNC
INHS
U. of Wise.
Total
P. Lewis
INHS
Cornell
CNC
Total
P. Lewis
M. Anderson
INHS
Cornell
MCZ
CNC
Total
Nymphs
5
1
1
7
12
1
2
3
18
10
3
1
3
1
1
19
4
1
1
6
1
8
2
11
4
1
4
2
11
Subimagos Images
Males Females Males
S. exiguum
3
1
6
10
5. femoratum
1 5
1 6
2 11
S. floridense
2
2
S. i. jrontale
1 5
2
1
3
8
1
2 19
S. fuscum
1
1
1
3
3
9
S. gildersleevei
1
1 3
1
1 5
S. i. heterotarsale
8 7 1
2
2
8
8 7 13
Females
2
1
1
1
5
9
2
11
1
1
2
2
4
1
1
2
4
3
1
8
1
3
4
Types
examined1
H, P of S. alabamae
and S. exiguum
P of S. alabamae and
S. exiguum
H, P
H
H
Hm
H, P of S. proximum
and S. /najiis
H
H, Hm
P of 5. rivulicolum
H of S. rivulicolum
and S. fuscum
H
P
P
P
P
H, A, P
H, A, P
65
-------
TABLE 3. SUMMARY OF COLLECTIONS EXAMINED — Continued
Collections
P. Lewis
M. Anderson
U. of Minn.
Cornell
Fla. A&M
CNC
INKS
Total
P. Lewis
M. Anderson
J. Flannagan
INKS
Cornell
F. Myers
Fla. A&M
U. of Wise.
MCZ
CNC
Total
P. Lewis
Cornell
CNC
INKS
Total
P. Lewis
INHS
Total
P. Lewis
CNC
INHS
U. of Wise.
Total
P. Lewis
J. Flannagan
Cornell
CNC
U. of Wise.
Total
P. Lewis
INHS
U. of Wise.
Total
MCZ
Total
Nymphs
34
5
1
40
24
19
1
32
1
1
1
1
1
81
2
9
2
13
3
2
5
3
3
6
5
5
Subimagos Imagos
Males Females Males Females
5. integrum
5 2 13 24
2 2
2
14 1
1
4
5 2 36 27
S. i. interpunctatum
10 4 11 12
22
4
3 1
2
1
1
3
10 4 47 13
5. ithaca
4 4 8 6 4
2 1
4 4 10 7
S. lepton
1
5
1 5
5. luteum
2 1
1
1
4 1
5. mediopunctatum
l
1
1
2 1
1 3 2
5. minnetonka
1 7 18 15
1
1
1 7 20 15
5. modestum
2
2
Types
examined1
P of S. wabasha
H, P of S. helium
P
H, P of S. wabasha
and 5. integrum
H, P
H, P of 5. conjunctum
and S. affine
P
H, T
H, P, T
P
P
H, Hm
H, Hm
H
H
H
H
66
-------
TABLE 3. SUMMARY OF COLLECTIONS EXAMINED — Continued
Collections
P. Lewis
M. Anderson
F. Myers
Fla. A&M
MCZ
CNC
INKS
Total
P. Lewis
Cornell
J. Richardson
Total
CNC
Total
P. Lewis
M. Anderson
F. Myers
Fla. A&M
MCZ
CNC
INKS
J. Richardson
Total
P. Lewis
M. Anderson
F. Myers
Fla. A&M
MCZ
CNC
INKS
J. Richardson
Total
P. Lewis
Nymphs
11
1
1
3
16
1
1
2
2
1
1
3
7
36
7
1
1
1
46
8
Subimagos Images
Males Females Males
S. nepotellum
1 2 7
1
2
2
1 2 12
S. pallidum
2
1
3
S. placitum
2
2
S. pudicum
l
l
1
2
3
8
5. pulchellum
238
1
2
2
2
2 3 15
S. quinquespinum
2 1 10
Females
5
1
1
7
2
1
3
13
1
1
15
19
Types
examined
P
H
H, P
H, P
H, P
H
H
H, P
H, P
H, P
Hm
H, Hm,
H, A,P
P
deposited
in INKS Museum
U. of Wise.
Total
P. Lewis
F. Myers
CNC
INKS
J. Richardson
Total
P. Lewis
J. Flannagan
Cornell
MCZ
CNC
INKS
U. of Wise.
Total
1
9
19
1
1
21
3
3
1
3
10
1
2 1 11
S. rubromaculatum
1
2
8
4
15
S. rubrum
2
1
6
1
3
13
19
4
2
1
7
1
2
3
H, A,P
H, A
H, A
H, Pof
H, P
H, P
5. varium
67
-------
TABLE 3. SUMMARY OF COLLECTIONS EXAMINED — Continued
Collections
P. Lewis
Cornell
Fla. A&M
INHS
J. Richardson
Total
P. Lewis
M. Anderson
F. Myers
Fla. A&M
MCZ
CNC
INHS
U. of Wise.
Total
P. Lewis
M. Anderson
U. of Minn.
Cornell
F. Myers^
Fla. A&M
MCZ
CNC
INHS
Total
P. Lewis
J. Flannagan
M. Anderson
U. of Minn.
Cornell
CNC
INHS
Total
Grand Total
Nymphs
1
1
2
27
1
1
2
6
37
38
13
5
1
2
2
2
63
17
2
1
3
1
24
497
Subimagos Imagos
Males Females Males
S. smithae
l 1
4
2 1 2
1
1
3 1 9
S. termination
2 2 10
1
2
2
4
2 2 19
S. tripunctatum
3 6 25
258
2
1 2
5
2
1 5
5 13 49
S. vicarium
1
1
1
2
5
56 54 419
Tvoes
Females examined1
H, P
1
1
1
3 H, P
17
1 H, P
Hm
18 H, Hm, P
23
5
2 H, P of S. birdi and
S. scitulum
2
2
H, P
1
2
37 H, P
1
1
242
iH = Holotype, P = Paratype, T = Topotype, Hm = Homotype, A = Allotype
2 Illinois Natural History Survey Collection, Urbana
3 Canadian National Collection, Entomological Research Institute, Ottawa, Ontario
4 Museum of Comparative Zoology, Cambridge, Mass.
68
-------
TABLE 4. STENONEMA COLLECTING SITES IN THE OHIO RIVER BASIN
(Site numbers are keyed on Figure 1, a map of the region.)
Site
no.
i
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
Date
4-29-68
*5-25-66
8-25-70
8- 7-68
10- 2-68
4-21-69
5-28-69
6- 4-69
8- 8-69
9-13-68
5- 5-70
10-20-69
5-27-70
10- 3-68
6- 6-67
7-18-68
8-13-69
10-10-69
*6- 6-66
*6- 2-66
*6- 2-66
1-16-69
2-18-69
8-24-66
*5-15-63
11- 9-66
7-15-66
*9- 5-67
7- 6-66
11-17-66
7-23-68
9-23-66
9- 5-67
8-26-69
* 10-22-65
6-23-69
7-24-69
8- 6-69
7-23-68
4-21-69
8- 4-69
Stream
Little Miami River
Salamonie River
Ohio River
Creek along State
Rt. 46
Shayler Run Creek
Lake White Inlet
Creek
Boiling Spring Creek
Scioto River
Little Miami River
Little Miami River
Eel River
Wabash River
Wabash River
Little Miami River
Wabash River
Ohio River
Ohio River
Flatrock River
Mohican River
South Branch
Oswego Creek
Little Wabash River
Great Miami River
Flatrock River
Location
1 mile east of
Newtown, OH
Pennville, IN
Cincinnati, OH
East of St. Leon, IN
South of Milford, OH
South of Waverly, OH
Munfordville, KY
Portsmouth, OH
Loveland, OH
Cincinnati, OH
Hoovers, IN
Linngrove, IN
Wabash, IN
Batavia, OH
New Harmony, IN
Louisville, KY
Sayler Park, OH
Columbus, IN
Danville, OH
Coneville, PA
Crossville, IL
Lawrenceburg, IN
St. Omer, IN
Notes1
H
B
B
B
B
H
H
H
P.H. 8.0 H
TDS 250
B
G
S
S
B
B
B
B
B
B
B
B
H
H
B
B
B
B
B
B
B
B
B
B
B
B
Enriched waters
H
H
N
B
PH 7.55 H
TDS 330 H
Species collected
tripunctatum, pulchellum, inter-
punctatum, quinquespinum
femoratum, scitulum,
interpunctatum
tripunctatum, integrum,
metriotes, terminatum
jemoratum, scitulum
tripunctatum, scitulum,
interpunctatum, femoratum
tripunctatum, interpunctatum
scitulum, femoratum,
tripunctatum
terminatum, pulchellum?,
tripunctatum
pulchellum, integrum,
quinquespinum,
interpunctatum, tripunctatum
pulchellum, quinquespinum,
interpunctatum, terminatum,
tripunctatum, integrum
interpunctatum, exiguum?
interpunctatum
interpunctatum
pulchellum
integrum, ares
integrum, interpunctatum
integrum, scitulum,
terminatum
interpunctatum
interpunctatum (ssp.
heterotarsale)
interpunctatum (ssp.
canadense), fuscum, ithaca?
interpunctatum
terminatum, tripunctatum,
integrum
ares?, interpunctatum,
nepotellum, pulchellum
69
-------
TABLE 4. STENONEMA COLLECTING SITES IN THE OHIO RIVER BASIN — Continued
(Site numbers are keyed on Figure 1, a map of the region.)
Site
no.
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
Date
4-21-69
8-26-69
8-22-70
7-23-68
8- 4-69
8-15-69
8-15-69
8-15-69
8- 5-69
7-14-69
8-25-69
10-14-69
7-30-68
7-18-69
7-20-69
7-20-69
7-21-69
7-22-69
7-22-69
7-23-69
7-23-69
7-24-69
7-21-69
8- 4-69
8- 4-69
8- 4-69
7-23-69
7-24-69
7-24-69
8- 4-69
8- 5-69
8- 5-69
8- 5-69
Stream >
Flatrock River
Ohio River
Sugar Creek
Kentucky River
Creek by U.S. 127
Paint Lick Creek
Moots Creek
Ohio River
Riffle Creek
Olady Fork
Laural Fork
Cheat River
East Br. West
Clarion River
Hitchcock Creek
Marvin Creek
Chapman Creek
Jackson Run
Laurel Run
Big Blue Creek
Wildcat Creek
Wildcat Creek
Minister Creek
Oswego Creek
Allegheny River
Wildcat Creek
Wabash River
Wildcat Creek
Mississinewa River
Location
St. Paul, IN
Anderson Ferry, OH
London, IN
Wilmore, KY
Northeast of Liberty, KY
Kirksville, KY
East of Ash Grove, IN
Madison, IN
Huttonsville, WV
Glady, WV
Beaver Dam R. S., WV
Rowlesburg, WV
West of Wilcox, PA
S. of Cherry Grove, PA
Marvindale, PA
South of Clarendon, PA
North Warren, PA
Bruceton Mills, WV
Shelbyville, IN
Prymont, IN
Rossville, IN
South of Sheffield, PA
Millport, PA
East of Coudersport, PA
Monitor, IN
Lockport, IN
lerome, IN
Matthew, IN
Notes1
H
M
B
B
H
PH 7.5 H
TDS 250
PH 7.5 H
TDS 330
PH 8.0 H
N
B
M
M
B
H
H
H
H
H
H
H
H
H
N
H
N
Enriched
PH 8.0 H
TDS 330
H, N
PH 7.2 H
TDS 90
H
PH 8.0 H
TDS 500
PH 8.5 H
TDS 500
rain swollen
water cloudy
PH 8.5, TDS 800
poll, evident
Species collected
ares
metriotes, integrum,
interpunctatum, scitulum,
terminatum
nepotellum, pulchellum?,
ares
femoratum, interpunctatum
scitulum, tripunctatum
tripunctatum? , femoratum,
scitulum
terminatum?
terminatum?, exiguum?,
integrum, interpunctatum,
tripunctatum?, pulchellum
rubromaculatum (No
Stenonema below mine
drainage area)
rubromaculatum, vicarium
rubromaculatum
rubromaculatum
rubromaculatum
rubromaculatum, gildersleevei? ,
interpunctatum
pudicum
rubromaculatum
rubromaculatum
interpunctatum
interpunctatum, terminatum
interpunctatum (2 ssp.),
terminatum, quinquespinum
interpunctatum (2 ssp.),
pulchellum
pudicum
rubromaculatum
vicarium
pulchellum
pulchellum, interpunctatum,
quinquespinum
rubrum, interpunctatum
pulchellum
70
-------
TABLE 4. STENONEMA COLLECTING SITES IN THE OHIO RIVER BASIN — Continued
(Site numbers are keyed on Figure 1, a map of the region.)
Site
no.
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
Date
8- 5-69
8- 6-69
9-17-69
9-17-69
9-24-69
8- 5-69
8- 5-69
8- 6-69
9-17-69
10- 6-69
3-19-70
8-13-69
8-13-69
* 10-2 1-65
*10-ll-66
* 10-22-65
5- 6-70
* 10-26-66
* 10-14-65
* 10-27-66
*5-23-67
*8-24-67
* 8-24-67
*9-22-66
*1 0-1 2-65
* 8-24-67
*11- 9-67
*10-13-65
*11- 3-67
*11- 1-67
* 10-27 -67
*11- 1-67
Stream
Wabash River
Big Walnut Creek
Mad River
Great Miami River
Cumberland River
Eel River
Tippecanoe River
Sugar Creek
Stillwater River
Turkey Run Creek
Little Kentucky River
North Fork of
Rough River
Sugar Creek
Mississinewa River
Sand Creek
Vermilion River
White River
Little Vermilion
River
Vermilion River
Riley Creek
Kickapoo Creek
Kokomo Creek
Big Duck Creek
Embarras River
Tradewater River
Little Eagle Creek
Wiley Creek
Slover Creek
Tradewater River
Greasy Creek
Location
Markle, IN
Greencastle, IN
West Liberty, OH
Sidney, OH
Cumberland Falls, KY
South Whitley, IN
Warsaw, IN
Crawfordsville, IN
Beamsville, OH
Friendship, OH
West of Carrolton, KY
Axtel, KY
Amity, IN
Peru, IN
Reddington, IN
Bismark, IL
Newberry, IN
Sidell, IL
Danville, IL
Charleston, IL
Charleston, IL
Kokomo, IL
Northeast of
Noblesville, IN
Charleston, IL
St. Charles, KY
Indianapolis, IN
Princeton, KY
Providence, KY
Kelly, KY
Madisonville, IN
Notes1
PH 8.5 H
TDS 580
below pollution
source
PH 8.0 H
TDS 300
PH 8.0 H
TDS 255
PH 8.0 H
TDS 300
H
PH 8.0 H
TDS 500
H
PH 8.0 H
TDS 385
H
H
H
H
H
B
B
B
B
B
B
B
H
B
H
H
B
H
H
H
B
H
Species collected
pulchellum
pulchellum, nepotellum
vicarium, pulchellum
pulchellum
pulchellum, metriotes?,
interpunctatum (ssp. jrontale)
interpunctatum (ssp.
heterotarsale )
interpunctatum (2 ssp.)
interpunctatum
interpunctatum, tripunctatum
scilulum, pulchellum,
tripunctatum, vicarium,
fuscum
scitulum
tripunctatum, scitulum
interpunctatum, tripunctatum
interpunctatum, pulchellum
interpunctatum, scitulum,
pulchellum, ares,
rubromaculatum, Carolina,
tripunctatum
interpunctatum, tripunctatum
interpunctatum, integrum, ares
rubrum, interpunctatum,
pulchellum, tripunctatum,
nepotellum
interpunctatum, pulchellum,
quinquespinum
interpunctatum
interpunctatum
interpunctatum
interpunctatum, tripunctatum
interpunctatum, scitulum
interpunctatum
tripunctatum
scitulum
scitulum
scitulum, interpunctatum
tripunctatum
71
-------
TABLE 4. STENONEMA COLLECTING SITES IN
(Site numbers are keyed on Figure 1,
THE OHIO RIVER BASIN — Continued
a map of the region.)
Site
no.
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
Date
*10-13-66
* 10-13-65
*4-18-67
*8- 3-67
*6- 3-38
*5-22-42
* 5- 10-46
8-28-69
*6- 7-46
*10- 7-67
7- 1-70
*10- 8-64
*4-17-46
8-25-69
*9- 5-67
7-24-68
9-12-68
6-16-70
8-29-69
Stream
Coal Creek
Middle Fork of Ver-
milion River
White River
Little Kanawha River
Beargrass Creek
Salt Fork River
Wabash River
Ohio River
Lusk Creek
Little Kanawha
River
Twelve Mile Creek
Reedy Creek
Muddy Creek
Ohio River
Ohio River
Ohio River
Ohio River
Ohio River
Scioto River
Location
Veedersburg, IN
Penfield, IL
Petersburg, IN
Palestine, WV
Louisville, KY
Oakwood, IL
Grayville, IN
Ironton, OH
Eddyville, IL
Glenville, WV
Monroe Township, OH
Palestine, WV
lewett, IL
Markland Dam, KY
Evansville, IN
Meldahl Dam, OH
Portsmouth, OH
Pittsburg, PA
Lucasville, OH
Notes*
H
H
B
S
H
H
B
B
H
S
H
S
H
B
B
B
B
B
B
Species collected
pudicum?, pulchellum
ares, rubrum
rubrum, pulchellum,
terminatum
interpunctatum
interpunctatum
interpunctatum
interpunctatum
interpunctatum
candidutn
tripunctatum
femoratum
luteum?
ares
pulchellum, integrum
integrum
integrum
integrum, terminatum
integrum
terminatum, exiguum
i Symbols
*Not collected by the author.
B, collected by basket sampler.
H, collected by hand from rocks and vegetation.
G, collected by grab.
S, collected by Surber sampler.
N, collected by net.
M, collected by multiplate sampler.
72
-------
APPENDIX C —DISTRIBUTION MAPS
TYPE LOCALITIES
•it S. annexum
• _S_. ores
S. ithoco
FIGURE 189. Distribution Map of S^ onnexum, _S. ores, and JK ithoto.
73
-------
TYPE LOCALITIES
• S. bipunctatum
O S. carlsoni
ffl S. floridense
FIGURE 190. Distribution Map of S. bipunctatum, _S; corlsoni, and £. floridense.
TYPE LOCALITIES
* S. candidum
FIGURE 191. Distribution Map of S. candidum, S. Carolina, and S. lepton.
74
-------
FIGURE 192. Distribution Map of S. exiguum, S. modestum, and S. ploeitum.
TYPE LOCALITIES
S. femorotum
• S. luteum
T S. pallidum
FIGURE 193. Distribution Map of^. femorotum, _S. luteum, and S^ pallidum.
75
-------
TYPE LOCALITIES
S. luscum
S. integrum
S. rivulicolum =tuscun
. bellum=integrum
T. wobosho=integrur
T metriotes=integrun
FIGURE 194. Distribution Mop for S. (uscum and £. integrum.
TYPE LOCALITIES
* S. gildersleevei
• S. medioponclatur
A S. minnelonka
FIGURE 195. Distribution Map of^
gildersleevei, ^. mediopunctotum, and ^. minnetonko.
76
-------
TYPE LOCALITIES OF S. INTERPUNCTUM SSP. AND VARIANT FORMS
Q S. interpunctolum ci S^ heterotorsale ir £. (laveolo
ir S. canadense Y S. mojus & proximum ^ ^. affine
O S. fronlale • S. ohioense & conjunctum ® ^ oreion
FIGURE 196. Distribution Map of S. interpunctatum Including Type Localities of Variant Forms.
FIGURE 197. Distribution Mop of £. nepotellum and S_. smithae.
77
-------
TYPE LOCALITIES
S. pudicum
• 5. quinquespinum
FIGURE 198. Distribution Map of ^. pudicum and S^ qu ing uesp inum.
TYPE LOCALITIES
* S. pulchellum
FIGURE 199. Distribution Map of S. pulchellum.
78
-------
TYPE LOCALITIES
T S. rubromaculatum
FIGURE 200. Distribution Map of S. rubromaculatum and S_. terminotum.
TYPE LOCALITIES
if S. rubrum
• S. varium = rubrum
FIGURE 201. Distribution Map of S. rubrum.
79
-------
TYPE LOCALITIES »'
* £. trlpunctotum i. i.
• S. bird! =tripunttotum s. s.
A S. tripunctatum scitulum
FIGURE 202. Distribution Mop of S. Iripunctotum Including Variant Forms.
FIGURE 203. Distribution Mop of S. vicorium ,Type locality somewhere in North America).
80
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-670/4-74-006
3. RECIPIENT'S ACCESSIOWNO.
4. TITLE AND SUBTITLE
TAXONOMY AND ECOLOGY OF STENONEMA MAYFLIES
(HEPTAGENIIDAE:EPHEMEROPTERA)
5. REPORT DATE
December 1974; Issuing Date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Philip A. Lewis
9. PERFORMING ORGANIZATION NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
10. PROGRAM ELEMENT NO.
1BA027: ROAP 05AEF: Task 05
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
16. SUPPLEMENTARY NOTES
T6, ABSTRACT
This manual provides keys and descriptions of all North American species of
Stenonema mayflies and consolidates information from the literature on their
ecology, environmental requirements, and pollution tolerance. Accounts of each
species include synonymy, nymphal description, collection records, and a distri-
bution map. The 31 species described and keyed include three recently described
species, four new synonyms, two resurrected species, and new combinations involving
three additional species and subspecies. Twelve species and one subspecies are
classified as intolerant to organic pollution, eight species as tolerant of mild
pollution, and seven species and two subspecies as tolerant to moderate pollution.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
*Taxonomy
*Aquatic biology
*Fresh water biology
*Indicator species
Benthos
Limnology
Life cycles
"Ecology
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
*Mayflies
Insect ecology
*Stenonema mayflies
*Pollution tolerance
Environmental require-
ments
6C
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
89
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
Form 2220-1 (9-73)
81
-ft U. S. GOVERNMENT PRINTING OFFICE. 1978-757-140/1465 Region No. 5-11
------- |