(Figs. 14, 23, 31, 38, 54, 62, 74, 83, 96, 109)
Distribution. Widespread west of the 100 th Meridian (Alaska, Alberta, British Columbia, California, Colorado, Idaho, Montana, New Mexico, Nevada, Oregon, Utah, Washington, Wyoming, Yukon).
Material examined. Utah: Salt Lake Co., Mill Creek east of Salt Lake City, 11-IV-1966, R. W. Baumann, 3♂ larvae, 2♀ larvae; Mill Creek, 0.8 km above Porter Fork, 27-IV-1981, K.W. Stewart, B.P. Stark, W.D. Shepard, & D.D. Zeigler, 6♂, 3♀, 6♂ larvae, 20 ♀ larvae. Washington: Whatcom Co., North Fork of the Nooksak River, 18-IV- 1988, K.W. Stewart, 1♂ and 1♀ reared with exuvia. (I.D. confirmed by R. W. Baumann).
Characters. Color, pigmentation (Fig. 14), maxillae (Fig. 31), body, leg (Fig. 54), and cercal setation, and sexual dimorphism (Figs. 62, 74, 83) generally typical of genus. Body length ♂ 7.5-8.5 mm, ♀ 8.5-9.5 mm. Antennal segments approximately 64. Cercal segments ♂ and ♀ 52. Male 9 th sternum (Fig. 96) ovate, with posterolateral sides convex and rounded apex. Female 9 th sternum (Fig. 109) ovate with posterolateral sides slightly convex and narrowly rounded apex.