256 
curved up and forward with tip forming 
a point; subanal lobes complicated, asym- 
metrical and, as viewed from above, are 
as in fig. 16. 
Length to tip of wings 10 mm. 
FremA.e.—Head, thorax, basal abdom- 
inal segments and appendages in general 
similar to those of male. Genital opening 
near middle of eighth abdominal sternite 
not covered by a plate. Ninth abdominal 
sternite prolonged to form plate reaching 
nearly to tip of abdomen and rounded at 
tip ie bo: 
Holotype, male-—Newfound Gap near Gat- 
linburg, Little Pigeon River, Tenn.: May 14, 
1939, TI. H. Frison & H. H. Ross. 
Allotype, female——Same data as for holo- 
type. 
yt paratypes. TENNESSEE. NEWFOUND GAP: 
Same data as for holotype, 22¢, 789. 
Nympu.—In general similar to the 
nymph of fasciata (Burmeister), as de- 
scribed by Frison (1929, p. 385). No 
longitudinal pale stripe on abdominal ter- 
vites, fig. 17. Platelike projection of ninth 
abdominal sternite somewhat broader than 
in fasciata, and abdominal tergites unt- 
formly brownish. 
Nymphal and exuvial specimens with 
same data as for holotype. 
This new species presents many struc- 
tures which place it close to the western 
Brachyptera nigripennis (Banks), from 
which it differs, however, in shape of 
supra-anal process, in shape of lobes at base 
of each cercus, and by the much-narrowed 
tip of the ninth abdominal sternite. It 
differs from B. pacifica (Banks), another 
western species, in lacking lobes at base of 
tenth abdominal tergite, by the much-nar- 
rowed tip of ninth abdominal sternite, and 
other characters. 
LEUCTRIDAE 
Leuctra Stephens 
At the time of the publication of The 
Stoneflies, or Plecoptera, of  Illinots 
(Frison 1935a), claasseni Frison (1929) 
was the only species of Leuctra known to 
occur in Illinois. Since then, intensive 
field work in exceedingly local, small and 
segregated habitats has revealed the pres- 
ence of two additional species. It becomes 
desirable, therefore, to record these new 
additions to the Illinois list, to illustrate 
the characters most useful in recognizing 
Intinois Natura History SURVEY BULLETIN 
Vol. 22, Art.@ 
the three Illinois species and to present a 
key for identifying them. 
KEY TO ILLINOIS SPECIES OF 
LEUCTRA ADULTS 
MALES 
1. Ninth abdominal tergite with a promi- 
nent, sharply outlined, deep, longitudi- 
nal cleft, fig. 184.9) 33 claasseni 
Ninth abdominal tergite without such a 
Cleft... 2. cc. oss oe 9 Reet 2 
2. Seventh abdominal tergite with a conspic- 
uous, rearward-pointing process, fig. 
VP ca Wee tenuis 
Seventh abdominal tergite without a spe- 
cial process, fig. 197 3 ¢ eee decepta 
FEMALES 
1. Eighth abdominal sternite about as long 
as seventh, with posterior margin in 
middle indented so that sternite is bi- 
lobed... . 2... ss. hjn ie 2 
Eighth abdominal sternite much shorter 
than seventh, posterior margin not bi- 
lobed; three small, separated, humplike 
areas on anterior margin, fig. 18..... 
Lee kee #e kd ene See claasseni 
2. Seventh and eighth abdominal sternites 
conspicuously fused ; cleft between lobes 
of posterior margin of eighth sternite 
wide and deep, sides and tips of lobes 
formed by a cleft more strongly and 
darkly sclerotized than rest of sternite, 
fig, 20.0.0... 2.8 (ee tenuis 
Seventh and eighth abdominal sternites 
indistinctly or weakly fused; cleft be- 
tween lobes of posterior margin of 
eighth sternite narrow, sternite almost 
uniformly sclerotized, fig. 19..... decepta 
Hanson (1941) in a recent paper has 
separated Leuctra as previously used by 
other North American workers into two 
genera, Leuctra Stephens and Paraleuctra 
Hanson. It is obvious to anyone who has 
closely studied a series of species of 
Leuctra (s.l.) that this genus contains 
some smaller complexes. Paraleuctra may 
be of generic rank, but, for the time being, 
pending a thorough revisional study of the 
Leuctridae, I prefer to recognize Para- 
leuctra as a subgenus. If Paraleuctra is a 
valid genus, it is probable that other addi- 
tional generic names will be necessary. 
Paraleuctra is represented in Illinois by 
claassenit F rison. 
Leuctra claasseni Frison 
Leuctra claasseni Frison (1929, p. 404). 
Original description, | 
é. | 
Leuctra claasseni Frison (1935a, Pp. 355). 
Description and new records, 9. | 
The original description of this species 
was based solely upon Illinois specimens 
