September, 1942 
pared with similar specimens in the IIli- 
nois Natural History Survey collection. 
In many respects longiseta is closely re- 
lated to mormona. The only characters 
which I have been able to locate to sepa- 
rate these two species are as follows: (1) 
YMPHAL MANDIBLES 
Wi Ta ae 
, 1) 
NYMPHAL 
MAXILLA 
ee pe 
Penn 
NyMPHAL LABIUM 
ADULT HEAD 
AND PRONOTUM 
4 y 
as \ Ee 
TENT 
VY) VEAL, 
ee 
ONAN NLT Zine 
EAS, UY GILES 
GABDOMINAL STERNIT 
fo) 
ABDOMINAL SEGMENTS 
Fig. 94.—Jsoperla longiseta, drawn from 
Texas specimens. 
Frison: NorrH AMERICAN PLECOPTERA 
319 
in the male of longiseta the lobe on the 
posterior margin of the eighth abdominal 
sternite is rounded, figs. 94 and 95, and 
the subanal lobes at the tip of the abdomen 
are long and slender; whereas in the male 
of mormona the lobe is more distinctly 
truncated or square and the subanal lobes 
are shorter and somewhat stouter; (2) in 
the female of longiseta the subgenital 
plate, figs. 94 and 95, is much produced, 
rounded and strongly sclerotized, whereas 
in the female of mormona it is much less 
produced and more weakly sclerotized; 
(3) in longiseta, both sexes, the pronotum 
has dark brown embossings that are more 
or less strongly contrasting in color with 
the remainder of the pronotum, figs. 94 
and 95, whereas in mormona the entire 
area, except for the median yellowish 
stripe, is more uniformly suffused with 
brown. 
In the Illinois Natural History Survey 
collection is a series of males, females and 
exuviae from El Paso, Tex., which I am 
identifying with some hesitation as longi- 
seta. All of the males of this series are 
brachypterous, fig. 96. Compared with 
longiseta specimens from Illinois and other 
states, fig. 95, these Texas specimens have 
the dark area on the dorsum of the head 
anterior to the ocelli more suffused, fig. 
94, and the modified subanal lobes appear 
shorter and stouter and in this respect 
a Na 
jay may 
\! Hs yy 
Deer f 
et ge ° 7 . B é : oy 
UN, MO es 
| fia 4 We ‘: 
ae 
a 
Lp EES 
di 
. mei ett? 
<4 Salts ‘ 
MUNN te AU pape HCH nH eee ae 
ADULT HEAD 
AND PRONOTUM 
\k 
\¥ s 
NE ne 1 
epee ete 
DOMINAL TERGITES 
BA 
Co AB 
Fig. 95.—Jsoperla longiseta, drawn from 
Mississippi River valley specimens. 
