September, 1942 
Hydroperla olivacea has rarely been re- 
corded in literature, except in catalogs, 
since its original description and it was 
entirely omitted by Needham & Claassen 
(1925) in their Monograph. Walker’s 
(1852) description was based upon a speci- 
men from “St. Martin’s Falls, Albany 
River, Hudson’s Bay.” Klapalek (1912) 
gave notes and an illustration of Walker’s 
type in the British Museum. More re- 
cently Ricker (1938) redescribed and 
figured the typic male; in addition he 
described a female associated with the 
typic male as the ‘“Neo-allotype,” and 
recorded an additional male specimen from 
~Hudson’s Bai, 1881,” in the collection 
of the Vienna Museum. 
eee inew!936- Dr, H. H. Ross and I 
collected at the Namakagon River, near 
Spooner, Wis., a single cast skin of A 
nymph easily distinguished from all other 
known North American stonefly nymphs 
by virtue of a peculiar curled process at 
apex of abdomen. In 1939, exuvial speci- 
mens of this same species were found at 
three places in northern Michigan; which 
Suggested that an earlier trip the next year 
might result in the capture of adults. Ac- 
cordingly, a trip to northern Michigan 
was made May 9-12, 1940, with the te- 
sult that numerous exuviae, one dead 
adult male in a spider web, one dead adult 
male partially emerged from nymphal skin 
in a spider web and one perfect live speci- 
men of a male adult were collected. 
Previous to the collection of adult speci- 
mens in 1940, Ricker’s (1938) illustration 
of the type of olivacea suggested that my 
exuviae with unique apical abdominal 
processes might be the cast skins of that 
species, since the adult male of olivacea 
has a most extraordinarily long supra-anal 
Process. Finding adult males of olivacea 
in spider webs under bridges where exu- 
viae were plentiful, and beating a fresh 
live male specimen from a bush where 
exuviae were present, afford sufficient evj- 
dence with such unique adults and nymphs 
(0 associate them definitely as the same 
species. Ricker’s illustration of the typic 
nale of olivacea is sufficient, too, to en- 
ible me to assign without question my 
1orthern Michigan specimens to the spe- 
‘ies olivacea. In many respects the stone- 
ly fauna of northern Michigan is similar 
0 that of Ontario, Canada. As a further 
id to the future recognition of this spe- 
Frison: NorrH AMERICAN PLECOPTERA 
“tet 
ABDOMINAL SEGMENTS 
297 
cies, an illustration showing the color pat- 
tern of the dorsum of the head and thorax, 
and important structural features of the 
male, fig. 68, is presented. 
Based upon exuviae and one shriveled 
nymph found dead in a spider web beneath 
a bridge, the following description of the 
heretofore unknown nymph of olivacea 
is presented. 
Nympu. — General color yellowish 
brown with black or fuscous areas as in 
fig. 69; particularly noticeable are the dark 
transverse bands on the anterior and pos- 
terior margins of the abdominal tergites, 
the bands on the anterior margins broad- 
est; 
NYMPHAL 
MANDIBLES 
iee. a, 
SHC 
NYMPHAL LABIUM 
Reas 
NYMPHAL 
MAXILLA 
aes ni 
ADULT HEAD 
AND PRONOTUM 
hes steht ' 
ite RTT 
| HW 
PMN ivirinsesse OTT) 
GC ABDOMINAL STERN 
——-— 
SSS 
——— 
== 
= Zz 
== 
== 
= 
SS 
| 
it 
\ 
a 
Te 
ve 
Z 
Ln 
== 
CG ABDOMINAL TERGITES 
Fig. 68.—Hydroperla olivacea. 
