May, 1953 
‘ 
“ee 
(ae ee 
= 
a a ae at mw OO Ea OP OO BS 
—— oe creamer a Sa FU ws 6 0 BE OE BO OS | 
PAF SOOO een) 
Fig. 88—Nymph of Neoephemera purpurea. 
(From Traver. Figure used by permission of 
the Comstock Publishing Company, Ithaca, 
New York.) 
the Javanese Neoephemeropsis, each cercus 
is also clothed, on the mesal side, with a 
dense comb of long setae, and the median 
caudal filament bears such a comb of long 
setae on either side. 
There are two described species of Neoe- 
phemera in North America. WN. bicolor 
McDunnough (19254:168) is known from 
Michigan, Quebec, and Georgia; purpurea 
(Traver) (1931a: 103; 1937: 34) is known 
from Florida, Georgia, North Carolina, 
and South Carolina. 
CAENIDAE 
This family corresponds to the subfamily 
Caeninae of the family Baetidae in Traver’s 
classification (1935a:629), and to the 
family Caenidae in Ulmer’s classification 
(1933: 206). 
Burks: THE Mayer tiers oF ILLINOIS 43 
The members of the Caenidae are among 
the most distinct of the mayflies. In most 
species, the individuals are small, but some 
attain a body length of 6 or 7 mm. The 
adult females are slightly larger than the 
males, but otherwise they are almost iden- 
tical in appearance; even the compound eyes 
of one are not larger than those of the 
other. In both sexes, each lateral ocellus 
is at least one-half as large as one of the 
compound eyes. The thorax is greatly de- 
veloped, while the abdomen is relatively 
small and contracted, giving these mayflies 
a rather thickset appearance. The fore wing 
is white, being quite cloudy or milky, the 
costal margins tinged with grayish lavender; 
the marginal ciliae are numerous, even in the 
imago stage. In all genera, the wings char- 
acteristically have very few crossveins, and, 
except in Leptohyphes, they are quite broad 
in the anal region, figs. 97, 98. The hind 
wing is wanting except in the subimago 
stage of the genus Leptohyphes. Each tarsus 
has five segments, figs. 11-13. The abdomen 
is somewhat broad and flattened dorsoven- 
trally, with the posterolateral angles of 
each segment obliquely produced. There are 
three well-developed caudal filaments, and 
the individual segments making up these fila- 
ments are relatively longer than in most 
mayflies. In the subimagoes, the filaments 
bear prominent setae, but in the adult males 
they are bare. The adult females retain, 
partly or completely, the subimaginal fila- 
ments. Especially in the females, the subim- 
aginal exuviae are often only partly shed. 
In the hairy nymphs, figs. 96, 113, 114, 
the head is hypognathous and the body some- 
what flattened dorsoventrally. The tarsal 
claws are relatively large and long, figs. 
93-95. The lateral margins of the ab- 
dominal segments are produced as spines or 
plates. The first abdominal segment has 
either a pair of single, filamentous gills or 
none. ‘The gills borne by the second ab- 
dominal segment are operculate, completely 
covering the gills on segments 3-6. There 
are three well-developed caudal filaments; 
the cerci bear setae on all sides. 
KEY TO GENERA 
ADULTS 
1. Fore wing with very few crossveins and 
with median intercalary vein extending 
to wing base, fig. 97; male genital for- 
ceps with only one segment, fig. 108. .2 
