May, 1953 
number, obliquely slanting, not anastomosed, 
and most not reaching vein Sc; hind wing, 
fig. 274, long and narrow, costal projection 
minute but always clearly present, third 
longitudinal vein absent, usually a single 
long intercalary vein present posterior to 
second longitudinal vein. Abdominal tergites 
2-6 dark brown, with anterolateral angles 
of each tergite pale yellow, a faint black 
circle at each spiracle; sternites 2-6 white or 
faintly yellow, sometimes with a brown, 
transverse streak at posterior margin of each 
sternite; apical tergites chocolate brown; 
sternites opaque white, shaded with brown 
on median area of basal half of each and 
laterally on apical sternite; genitalia white, 
with second segment of forceps semiquad- 
rate, fig. 292; caudal filaments white. 
Known from Illinois, Ontario, Quebec. 
Illinois Records.—Des PLaiNnes: Fox 
River, May 26, 1936, H. H. Ross, 1¢. 
Oakwoop, Salt Fork River: May 29, 1948, 
Burks & Evers, 24 ; June 5, 1948, Burks & 
Sanderson, 56. West Cuicaco: July 9, 
1948, Ross & Burks, 2¢. 
8. Baetis baeticatus new species 
This species resembles frondalis in the 
structure of the hind wing and the male 
genitalia; the two differ in that the body of 
baeticatus is strikingly slender and _ long, 
being longer than the fore wing, while the 
body of frondalis is shorter than the fore 
wing. They also differ in color, baeticatus 
having a medianly interrupted, transverse, 
red stripe at the posterior margin of each of 
abdominal tergites 2-6, and these tergites 
are faintly stained with brown; in frondalis, 
abdominal tergites 2—6 are almost com- 
pletely dark brown, with the red _ stripes 
wanting. 
Matre.—Length of body 6.0 mm., of fore 
wing 5.5 mm. Head dark brown, white at 
lateral angles of frontal shelf; each antennal 
scape white, with faint brown shading at 
base and at apex, pedicel tan, flagellum white 
at base, shading to tan at apex; ocelli white; 
each compound eye with stalk relatively 
low, lateral margin of upper faceted portion 
almost touching upper margin of lower por- 
tion, upper portion golden brown, lower 
black. Thorax dark brown, mesonotum yel- 
low at anterior end of each outer parapsidal 
furrow, on prescutum, and on scutellum; 
pleural sutures white, mesosternum light 
Burks: THE Mayrties or I[LLINoIs 
129 
yellow-brown in center, dark brown at mar- 
gins; all coxae partly shaded with dark 
brown, legs otherwise white, except that 
fore tibia is slightly darkened at apex; fore 
tibia one and one-half times as long as fore 
femur, fore tarsus four-fifths as long as 
fore tibia, second fore tarsal segment one 
and one-half times as long as third, fourth 
and fifth segments equal in length and each 
one-half as long as third segment; wings 
hyaline, base of each fore wing and basal 
halves of veins Sc and R, stained with 
brown, stigmatic crossveins six in number, 
all uniformly slanted, not anastomosed and 
most not quite reaching vein Sc; no marginal 
intercalaries in subcostal interspace, a single, 
short intercalary present in first R, inter- 
space, two well-developed ones in each of 
the two following interspaces; hind wing 
long, narrow, with a minute costal pro- 
jection, third longitudinal vein absent, a 
single marginal intercalary vein present pos- 
terior to second longitudinal vein. Abdomi- 
nal segments 2-6 with white ground, tergite 
2 suffused with brown stain over all but an- 
terolateral triangles, tergites 3-6 faintly 
brown stained on posterior third of each, 
a medianly interrupted, red band at pos- 
terior margin of each of tergites 2-7, and a 
pair of large, black tracheal marks in a 
cluster covering most of posterolateral area 
of each of tergites 2-6; a double, longitu- 
dinal, black spiracular line extending length 
of abdomen on either side, and a prominent, 
black spot at each spiracle on segments 1-6; 
apical tergites dark yellow-brown, sternite 
7 white, 8 brown stained, 9 with lateral 
margins dark brown; genitalia white, first 
forceps segment quadrate, second cylindrical, 
third slender and slightly bowed, fourth as 
wide as long; a prominent spine present in 
a median depression between bases of for- 
ceps; caudal filaments white. 
FEMALE.—Size as in male. Head and 
thorax dark brown, similar to those of male, 
legs and wings as in male; abdominal ter- 
gites uniformly dark yellow-brown, red 
crossbands of male absent, but black spirac- 
ular and tracheal markings present; sternite 
1 faint brown, sternites 2-8 white, with a 
pair of submedian, brown dots at anterior 
margin of each; sternite 9 brown at lateral 
margins; caudal filaments tan at bases. 
Holotype, male.—Wichert, Illinois, June 
11, 1947, L. J. Stannard. Specimen in alco- 
hol. 
