(Figs. 10, 20, 30, 40)
Diagnosis. This species can be recognized by the combination of the black body with white, medially interrupted tergal maculae; second recurrent vein basal to second transverse cubital vein; vertex lacking light maculae; apical terga without pubescent bands; and the pale erect hairs of T 6. Stelis alta is the only species in this group with extensive white banding on the terga. Stelis alta is similar to S. lateralis in size and markings, but differs by the second recurrent vein basal to the second transverse cubital in the former species.
Description. Female. Length 6 mm, forewing 4.5mm long. Black; mandible medially, below eye, highlights on apical margins of terga, sterna reddish brown; T 1 – T 5 with wide submedian yellowish-white bands, interrupted medially. Pubescence white, recumbent and erect on head, mesosoma. Punctation close, coarse on head, mesosoma, surface shiny; terga densely pitted, more so apically, surface somewhat shiny; sterna densely punctate, somewhat shiny except apically on S 6; labrum punctate on apical half. Clypeus scarcely convex in profile head broader (1.2 X) than long; gena narrower (0.7 X) than width of eye; IOD <(0.8 X) OOD, OOD = OPD, OPD> (1.4 X) LOPD, IOD> (2.7 X) LMOD, DLID> (1.2 X) BLID; pronotal lobe carinate; apical tibial spines minute on foreleg, larger on midleg, reduced to blunt point on hindleg; tarsal-tibial ratios: TIB> (1.5 X) BAT> (1.2 X) TAR; gradular crease moderately deep, terga not swollen laterally; apical margin rimmed; pseudomargin of T 6 rounded apically, with lateral shoulder near base (Fig. 20); S 2 – S 5 slightly swollen across middle; S 5 depressed basally; S 6 round apically.
Male. Similar to female except: gradular crease deeper; S 2 indented medioapically; S 3 apical margin indented with overhanging shiny tubercle medially (Fig. 30); S 4 with median comb about 3 X as wide as long, central depression narrow, rimmed mediolaterally by impunctate rim (Fig. 40); apical pubescent band on S 3 short, length less than length of outer hindtibial spur.
Type material. Holotype female. “UTAH Cache Co. Logan Cyn. (upper) 16 -VI- 72 Frank Parker”. Paratypes. UTAH, Cache Co: 1 Ƥ, 1 3, Logan, 6000 ', 20 Jun 1947, Phacelia heterophylla, GE Bohart; 1 Ƥ, Franklin Basin, 25 Jul 1971, GE Bohart; 1 Ƥ, Logan Cyn., 13 Jul 1947, R Bohart; 1 Ƥ, High Creek Cyn., NE Richmond, 10 Aug 1972, D.Vincent; 1 3, Willard Peak, 8000 ', 14 Jul 1953, GE Bohart, ER Cross; 1 Ƥ, Naomi Peak trail, N Tony Grove Lake, 8200-8600 ’, 17 Jul 1995, T Griswold; 1 3, Wellsville Mts., trail E Stewart Pass, 7200-7800 ’, 7 Jul 1995, T Griswold; 1 3, Willard Peak, under rocks nest of Anthocopa abjecta, reared, FD Parker; 9 Ƥ, Mt. Naomi, 0.30 kmNE, 41.9315 °N 111.6721 °W, 24 Jul 2008, H Ikerd; 2 Ƥ, Mt. Naomi, 0.21 kmNNE, 41.9312 °N 111.6737 °W, 24 Jul 2008, T Griswold; 1 Ƥ, same except Penstemon sp.; Ƥ 5 Ƥ, 3 3, Mt. Naomi, 9970 ', 41.9914 °N 111.6744 °W, 5 Aug 2005, Z Nyiro, FD Parker; Salt Lake Co: 1 Ƥ, Clayton Peak, 1.7 miNNW, 40.6148 °N 111.5721 °W, 31 Jul 2008, T Griswold. IDAHO, Franklin Co: 1 Ƥ, Beaver Creek, 30 Jul 1995, FD Parker. Oneida Co: 1 3, Weston Reservoir, 22 Jun 1997, pan trap, FD Parker. Additional material. IDAHO, Blaine Co: 1 Ƥ, Hulen Meadows, 2 mi N Ketchum, 14 Jul 1987, S Luce. NEVADA, Elko Co: 1 3, 1 Ƥ, Angel Lk., 8200 ', E. Humboldt Range, 22 Jul 1978, T Griswold. WYOMING: Sunlight Basin, N Cody, 15 Jul 1962, GE Bohart. Holotype and paratypes deposited in BBSL.
Biology. This species has been reared from nests of Atoposmia abjecta (Cresson) which builds cells with masticated plant material under rocks (Parker 1975).
Distribution. Northern Nevada, northern Utah, southern Idaho, and Wyoming.
Etymology. This is species is named in reference to the montane habitat of this bee.