Reprinted with permission of the Pan-Pacific Entomologist from:
LaBerge, W. E. 1971a. A new subgenus of Andrena found in California and Oregon (Hymenoptera: Apoidea). Pan-Pacific Entomologist 47: 47-57.
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This small, brightly colored species is closely related to A. crudeni. Like A. crudeni, it differs from A. torulosa by lacking the pronotal humeral angle and ridge. The female of A. subnigripes differs from that of A. crudeni by having the metasomal and leg hairs black and the thoracic hairs fulvous to fox-red. The male of A. subnigripes differs from that of A. crudeni by having black hairs on the last few metasomal Segments and having dark ochraceous thoracic hair. Viereck's (1916) original description of the A. subnigripes female is excellent.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 10-12 mm; width, 3.0-3.5 mm; wing length, M = 3.74 ± 0.099 mm; FL/FW, M = 0.84 ± 0.003; FOVL/FOVW, M = 3.09 ± 0.050.
INTEGUMENTAL COLOR. — As in A. torulosa but terga not at all translucent apically and tibial spurs dark reddish-brown.
STRUCTURE. — Head structure and sculpturing as in A. torulosa except as follows: maxillary palpus with segmental ratio about 1.0:1.0:0.9:0.7:0.6:0.7; labial palpus with ratio about 1.0:0.5:0.5:0.4. Thoracic and metasomal structure and sculpturing as in A. torulosa except pronotum completely lacks humeral angle and dorsoventral sludge, surface dull, finely and regularly tessellate and terga 1-4 with apical areas slightly shinier.
VESTITURE. — Head hairs dark ochraceous to fulvous with dark brown hairs usually present on vertex and on all specimens along inner margins of eyes, on lower parts of genal area, on mandibles and labrum, in facial fovea and a few dark brown hairs mixed with the paler hairs on clypeus especially apically. Thorax fulvous to bright fox-red above, fulvous on sides and a few dark brown hairs ventrally. Metasomal hairs black or blackish-brown except tergum 1 basally and tergum 2 at extreme base at sides; first two sterna with hairs often pale. Leg hairs black ; to dark brown except hind trochanteral flocculus ochraceous and usually some; femoral hairs pale; fore coxae with long spine-like hairs dark brown. Hair form and pollen collecting hairs as in A. torulosa.
MALE. MEASUREMENTS AND RATIOS. — P( = 4; length, 9-10 mm; width, about 2.5 mm; wing length, 3.35-3.50 mm; FL/FW, 0.78-0.79; FS1/FS2, 2.00-2.50.
INTEGUMENTAL COLOR. — As in A. torulosa.
STRUCTURE. — Head structure and sculpturing as in torulosa except as follows: /§ maxillary palpus with segmental ratio about 0.9:1.0:0.9:0.9:0.6:0.7; labial palpal " ratio about 1.0:0.6:0.4:0.6. Thoracic and metasomal structure and sculpturing as 'S-in torulosa except as follows: pronotum completely lacks humeral angle and H dorsoventral ridge, surface finely and regularly tessellate; terga 1-5 with apical g areas shiny, shagreening extremely delicate; terminalia as figured (Figs. 11-15), i§ note gonocoxites with apical processes less falcate; note shape of volsellae; sternum 8 with apical area with median hairs stout but not short as in torulosa.
VESTITURE. — Head and thoracic hairs ochraceous to pale fulvous. Metasomal hairs ochraceous except last three or four terga and sterna with dark reddish-brown hairs. Leg hair ochraceous except as follows: inner surfaces tarsi dark brown (hind) to reddish-brown (fore and middle); hind tibia with outer surface; with some brown hairs along posterior margin and surrounding basitibial plate; middle tibia with outer surface with brown hairs at least apically.