70 ILtinois NaTuRAL History Survey BULLETIN 
15. Ephemerella ora Burks 
Ephemerella ora Burks (1949:235). 
Mare.—Length of body 7 mm., of fore 
wing 8 mm. Head and body yellow, shaded 
with tan and brown. 
Head yellow, shaded with tan between 
eyes and around ocelli; eyes pinkish tan; 
each antennal scape and pedicel yellow, 
flagellum brown. Thorax yellow, with tan 
shading on dorsomedian area of pronotum, 
mesonotum mostly tan; legs yellow, with 
apex of each fore tibia and apex of each of 
the basal three fore tarsal segments dark- 
ened; wings and veins hyaline, with an- 
terior two veins of fore wing stained with 
faint yellow. Ground color of abdomen 
yellow, basal tergites with mid-dorsal area 
of each heavily shaded with brown, apical 
three tergites pinkish tan; eighth sternite 
with posterolateral angles pink; genitalia, 
fig. 127, yellow; caudal filaments light yel- 
low, articulations black. 
FeMALE.—Length of body 7.5 mm., of 
fore wing 9 mm. General color similar to 
that of male, but lighter; caudal filaments 
white, articulations black. 
Known from Illinois. Apparently a large- 
river species. 
Illinois Record—Mounr CarMeEt: 
April 22, 1946, at light, Mohr & Burks, 12, 
Lo. 
16. Ephemerella excrucians Walsh 
Ephemerella excrucians Walsh (1862:377). 
Ephemerella semiflava McDunnough 
(1927b:300). New synonymy. 
McDunnough (1931d:192) long ago ex- 
pressed the opinion that semiflava would 
prove to be a synonym of excrucians. 
Mave.—Length of body 5.5—-7.5 mm., of 
fore wing 7-9 mm. Dorsum of thorax dark 
red-brown, dorsum of abdomen varying 
from dark red-brown to almost black; ab- 
dominal venter slightly lighter in shade than 
dorsum. 
Head red-brown; eyes yellow in living 
insect; each antennal pedicel red-brown, 
flagellum smoky brown. Legs yellow, seg- 
ments of each fore tarsus darkened at tips. 
Wings hyaline, veins at costal margin of 
fore wing slightly yellowish; other veins and 
all crossveins hyaline; sometimes a faint 
red-brown staining present at bases of 
wings. Caudal filaments white, basal artic- 
ulations light red-brown. Genitalia, fig. 137, 
Vol. 26, Art. 1 
with penis lobes only slightly expanded near 
apexes, each lobe bearing two or three short, 
stout dorsal spines in basal position, and 
sometimes one or two lateral spines on 
either side; second segment of forceps 
straight and not expanded at apex. 
Nympu.—( Described from two specimens 
reared in Michigan by Dr. J. W. Leonard.) 
Length of body 5-6 mm., caudal filaments 
3 mm. General color dark brown, with 
relatively large, pale markings; caudal fila- 
ments white or pale yellow, with faint, 
darker crossbands throughout. 
Head, thorax, and abdomen entirely with- 
out dorsal tubercles; maxillary palps present, 
segmented; each tarsal claw with seven or 
eight ventral denticles; posterolateral angles 
of abdominal segments 4-9 produced as 
small, relatively blunt spines; caudal fila- 
ments bearing long, dense setae in apical 
areas. 
Known from Illinois, Michigan, New 
Brunswick, Oklahoma, Ontario, and Que- 
bec. The only Illinois specimen of this 
species I have seen is the lectotype in the 
Museum of Comparative Zoology. Now 
known to develop in a cold, rapid river. 
Illinois Record—Rock IsLanp: 124, 
5 9, B. D. Walsh (Walsh 1862:377). 
17. Ephemerella dorothea Needham 
Ephemerella dorothea Needham (1908:190). 
Ma ve.—Length of body 5-6 mm., of fore 
wing 7-8 mm. Head and body pale yellow, 
almost white. Eyes light red, antennae 
yellow. Thorax pale yellow, without darker 
shading; wings and veins hyaline; legs en- 
tirely yellow, with each fore tarsus faintly 
darkened. Abdomen entirely light yellow, 
without darker areas or shading; caudal 
filaments white, articulations not darkened. 
Genitalia, fig. 132, light yellow, with each 
penis lobe bearing six to eight stout spines 
in basal position; second forceps segment 
enlarged at apex. 
NympH.—Length of body 6-8 mm., of 
caudal filaments 4-5 mm. General color 
pale yellow-brown, with small, light tan, 
freckle-like spots and larger, pale markings; 
each caudal filament usually with two or 
three narrow, brown crossbands near tip. 
Head, thorax, and abdomen entirely with- 
out dorsal tubercles; maxillary palps well 
developed; each tarsal claw with six to 
nine denticles; posterolateral angles of ab- 
