258 
lated to tenuis (Pictet) than to claassent 
Frison. 
New locality records are as follows. 
ILLrnois.—Herop, spring tributary to Gib- 
bons Creek: May 24, 1940, C. O. Mohr & B. D. 
Burks, 3 (2 reared), 39, 7 nymphs; May 29, 
1939 Bat Burks a Cage Riegel, 2¢, 1 
nymph; May 30, 1940, B. D. Burks, 4 nymphs. 
EppyvILLE, Lusk Creek: May 24, 1940, C. O. 
Mohr’ & B.D. Burks, 24, 29; 5 nymphs; 
June 1, 1940, B. D. Burks, 16, 292, 1 nymph. 
FLoripA.—Leon County, 12 miles west of 
TALLAHASSEE: Noy. 30, 1939, L. Berner, 22. 
GEORGIA.—RABUN CouNTY, small creek flow- 
ing into Lake Burton: June 22, 1940 SH SsE. 
Hubbs, 12. 
Marine.—New Limerick, Hunter Brook: 
Aug. 25, 1937, T. H. Frison & Teele lirison,; 
el eiow 
MINNESOTA. — LAKE CouNTy, Encampment 
River: Aug. 5, 1939, B. T. Peters & R. H 
Daggy, 54; July 4, 1938, H, Knutson, 1% 
New BruNswicK.— ANAGANCE: Aug. 21, 
19392 1. Hy bison, & lao: Frison, Jr., 1¢. 
New YorkK.—Coip Brook: June 22 and 30, 
1940, H. Dietrich, 6 6, 9 2. CAROLINE, Wild 
Flower Reserve: Aug. 16, 1928, T. H. Frison, 
42. 
NortTH CAROLINA.——NEWFOUND GAP: 
13.41935) (Liat a Rossys2 4. 
Nova Scoria.—Moser River, Goldmine Brook 
cascades: July 19, 1939, J. A. C. Nicol, 82. 
SPRINGHILL JUNCTION: Aug. 21, 1939, oar: 
Frison & T. H. Frison, Jr., 3¢. Moose RIVER: 
Aug. 21, 1939, T. H. Frison & Te H. Frison, 
Jr. 1¢. IncRAMpPoRT: Aug. 22, 1939, Th: 
Frison & T. H. Frison, Jr. 1¢. 
ONTARIO.—ALGONQUIN Park, Costello Lake: 
various dates, June, July, August and Septem- 
ber, 1938 and 1939, W. M. Sprules, ¢ re OSes 
TENNESSEE. — GATLINBURG: June 13, 1940, 
T. H. Frison et al., 56; Sept. 4, 1940, B. D. 
Burks, 4¢, 99. 
ViIRGINIA.—MounrTAIN Lake, Hunters Branch, 
3,500 feet elevation: July 28, 1941, A. C. Cole, 
[ano 
Several nymphal specimens show anal 
gills as first illustrated for claassent 
(Frison 1935a). Since tenuis (Pictet ) 
nymphs also show these anal gills, all 
three of the Illinois species of Leuwctra 
possess them. These anal gills are so deli- 
cate, however, that they are easily lost by 
the nymphs or overlooked in specimens. 
June 
Leuctra tenuis (Pictet) 
Nemoura tenuis Pictet (1841, p. 375). Orig- 
inal description. 
As in the case of decepta Claassen, the 
finding of tenuis in a segregated relic 
habitat in Illinois adds another species to 
the Illinois stonefly faunal list. Its find- 
ing is additional evidence that each local- 
ity, stream and other habitat, no matter 
Ittrno1is NaturAL History SuRVEY BULLETIN 
Vol. 22, Arto 
how restricted, must be searched repeated- 
ly at various seasons of the year if state 
faunal lists of stoneflies are to approach 
completeness. Diagnostic structures of the 
adult insects of tenuis are illustrated in 
figs 20: 
The type of tenuis came from Pennsylvania, 
and Needham & Claassen (1925) have added 
the additional state record of New York. The 
geographical range of this species will un- 
doubtedly be greatly expanded with future 
collecting, as the following new records for its 
occurrence indicate. 
ILLINOIs.—ELcIN, Botanical.Gardens: Sept. 
19, 1939, H. H. Ross & C. O. Mohr, 94, 49. 
Maine.—NeEw Lim_erick, Hunter Brook: Aug. 
25, 1939, T. H. Frison & T. H. Frisonpaga 
Se 
MIcHIGAN.—OTSEGO COUNTY, west branch 
Sturgeon River: June 24, 1936, J. W. Leonard, 
24,22; July 9, 1937, F. E. Lyman, 16, 19. 
fe ABDOMINAL STERNITES 
SSS 
3’ ABDOMINAL TERGITES 
Go ABDOMINAL STERNITES 
AL, SEGMENTS 
NWN 
A “8 
LATED sel 
al 7 : 
Ps 
Le \ REN. 
— ah PAS 
eee | =. \ 
0 
== ae: 
+} a\ 
sags 
| 
} 
i hi 
ti hi HHI Fin AN 
| ae ia | } " “ 4 
Ee MS 
ee aN 
AWE a Sus. 
Fig. 20.—Leuctra tenuis. 
