154 
Psyche 
[June-September 
Key to Cyphoderris Species 
(Males only) 
1. Subgenital plate (IXth sternum) with prominent ventrally- 
directed process (Figures 4a, b) 2 
Sternal process absent (Figure 4c) C. buckelli Hebard 
2. IXth sternum strongly produced posteriorly; sternal process 
with an angularly forward-bent tip, often appearing terminally 
cleft and toothed; styli of IXth sternum depressed, sublanceo- 
late (Figure 3b); Ander’s organ ridge-patch present and thoracic 
teeth robust; fastigiurn often weakly rugose 
C. monstrosa Uhler 
Posterior of sternal process not angular but rounded, never 
terminally cleft and toothed (Figure 3a); Ander’s organ absent 
or if present, only as weak thoracic teeth; styli of IXth sternum 
mitten-like; fastigiurn smooth ... C. strepitans new species 
Geographical Distribution 
C. strepitans, as presently known, is confined to the mountains of 
Colorado and Wyoming (Figure 5). Its distribution is disjunct from 
that of buckelli and monstrosa. The broad valley of the Snake River 
isolates it on the northwest from the most southerly populations of 
Idaho monstrosa; if overlap occurs it must be north of Yellowstone 
in southern Montana. 
C. monstrosa is found from the Canadian Rockies in the south- 
west corner of Alberta, west through southern British Columbia. It 
reaches much farther north than buckelli, to Quesnel and to 
Sinithers B.C. (This latter record exceeds the northern extent of our 
map and could not be plotted; Sinithers is about 700 miles north of 
the Canada/ U.S. border.) A western arm of monstrosa extends 
down the Cascades, reaching almost to northern California. A less 
documented eastern arm crosses western Montana to a cluster of 
localities in the Salmon River Mts of central Idaho. 
C. buckelli has a more restricted range. It lies between these arms, 
overlapping broadly with monstrosa in southern B.C. and extending 
south through northern Idaho. There are interesting isolated rec- 
ords from Columbia Falls, Montana and from near Seneca in east 
central Oregon. Though their distributions overlap substantially we 
have not found monstrosa and buckelli together at the demic level. 
