16 
Rowland M. Shelley 
Figs. 2-8. 2 - 6 , S. piger. 2 , tibia of leg 13 of male from Teton County, 
Wyoming. 3 , tibia of leg 17 of male from Mineral County, Montana, 4 , 
distal extremity of telopodite of male from Mineral County, Montana, dor- 
sal view. 5 , left gonopod of male from Teton County, Wyoming, medial 
view. 6 , the same, lateral view. 7 - 8 , S. columbianus. 7 , left gonopod of 
paratype, medial view. 8, the same, lateral view. dl. distal lamina; e, 
endomerite; 11 , lateral lamina; ml, medial lamina; tt, tibiotarsus. Scale line 
= 0.5 mm for all figures. 
Diagnosis — Tibiae of legs 13-20 in males with distal lobes on 
anterior and/or caudal margins (Figs. 2-3); endomerite subequal in 
length and closely appressed to tibiotarsus; medial lamina extend- 
ing for about half the length of endomerite, with short but broad 
basal lobe, overhanging and obscuring inner margin of endomerite; 
distal lamina with two blunt teeth; lateral lamina extending for about 
2/3 of length of endomerite, expanding slightly distad, with or without 
small marginal spurs, not overhanging margin of stem (Figs. 4-6); 
paranota of segments 5-9 reduced in females. 
Variation — There are slight differences among the male gonopods 
that do not conform to a geographic pattern. The lobe on the me- 
dial lamina is located slightly distal to the pulvillus on a few males, 
and the spur proximal to the latter is absent from other. The teeth 
on the distal lamina are greatly reduced in individuals from Box 
Elder County, Utah, where they are more like small, rounded lobes, 
and the lateral lamina is expanded with slight marginal spurs in a 
few males from northern Idaho and western Montana (Fig. 4). 
