Reprinted by permission of the Regents of the University of California from:
Thorp, R. W. 1969. Systematics and ecology of bees of the subgenus Diandrena (Hymenoptera: Andrenidae). University of California Publications in Entomology 52: 1-146.
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This species is most closely related to A. chlorosoma and more distantly to A. subchalybea. It may be separated from the latter by its deeper closer punctures on the mesoscutum and scutellum and the deeply dissected apex of the labral process. From A. chlorosoma it is distinguished by the deeply dissected apex of the labral process, which in the female produces long, narrow apicolateral teeth which are recurved.
This species is represented by relatively few specimens from many localities over a wide geographic range. The presence of varying amounts of pale pubescence on the face and thorax of females from some localities in Nevada, Utah, and Wyoming is difficult to interpret. Each case is based on a single female, so it is presently impossible to evaluate these in light of the range of variation of their populations or to determine how these populations relate to one another.
FEMALE. — Integument dark blue with greenish reflections on basal elevations of metasomal terga; antenna basally and above apically dark brownish-black, apical 5 to 6 flagellar segments brown below, forewing with stigma pale yellow-brown, clypeus with subapical, narrow, transverse dark band, slightly produced upward medially with violaceous reflections; pubescence dark, black on head except occiput golden, black on thoracic pleura and metasomal sterna, black and golden intermixed on thoracic dorsum, blackish on hind legs except golden anterodorsally on tibial scopae, golden on metasomal terga except black anal fimbria; facial fovea with black sheen, tomentum brown. Head moderately dull, closely, coarsely punctate with tessellate interspaces; clypeus, latero- and supraclypeal areas with punctures separated by less than one diameter; facial fovea extending from summit of eye to bottom of antennal base; eye slightly arcuate medially; antenna with segments 1 to 3 of flagellum as 15:5:5; labrum with process elongate, reflexed and deeply emarginate (bidentate) apically (fig. 39); subgenal coronet long, well developed; gena moderately dull, moderately coarsely punctate with tessellate (minutely vertically striate) interspaces, punctures separated by 2 diameters; pubescence of clypeus moderately long, moderately sparse, subdepressed. Mesosoma dull, moderately coarsely punctate with tessellate-granular interspaces; pronotum with punctures irregularly spaced separated by less than 1 to 3 diameters, dorsolateral angle absent, without lateral fold; mesoscutum with punctures separated by one diameter; notaulus indistinct, scutellum with punctures separated by less than one diameter; metanotum rugose-punctate; propodeum rugose-punctate, punctures separated by less than 1 to 2 diameters, enclosure irregularly rugulose basally and medially, forming an inner rough triangle, more finely striate apicolaterally; episternum 2 rugose-punctate; wing lightly infuscated, submarginals 1:2 (41:41), stigma : rest of marginal cell (17:26.5), hind wing with jugal lobe narrow and without incision between it and vannal reaching beyond level of cu-v; posterior trochanter with long, curved, gray, perfect floccus; tibial scopa long, dense, with hairs of posterior half of outer face and posterior face branched; posterior hairs of scopa about one and one-half times as long as tibia at apex; pubescence of mesoscutum moderately dense with few long black and numerous moderately long golden hairs intermixed. Metasoma moderately shiny, moderately finely, sparsely punctate with tessellate interspaces; punctures on basal elevation of first tergum separated by 2 to 3 diameters; terga 2 to 4 with punctures of basal elevations separated by 2 diameters; depressed apical margins of terga 1 to 4 with punctures finer and more sparse; pubescence on basal elevation of tergum 1 moderately long, erect, on basal elevations of terga 2 to 4 moderately short, erect; apical depressed margins of terga 1 to 3 with spatulate hairs laterally forming weak, medially interrupted hair bands, tergum 4 with complete hair band of spatulate hairs. Length 9.5 to 10 mm, forewing 7 to 8 mm.
MALE. — Integument blue with greenish reflections especially on basal elevations of metasomal terga; antenna uniformly dark brownish-black, forewing with stigma pale brown, clypeus with narrow, transverse, subapical, dark band with violaceous reflections; pubescence pale, white except anal fimbria golden, narrow band laterally on face above and behind eye black. Head moderately shiny, coarsely, densely punctate with tessellate interspaces; clypeus, latero- and supraclypeal areas with punctures separated by less than one diameter; parocular depression short, linear; eyes convergent below; antenna with segments 1 to 3 of flagellum as 15: 6.5: 8; labrum with process strongly recurved, apically deeply emarginate with teeth somewhat divergent (fig. 40); mandibles moderately short; gena moderately shiny, tessellate, with fine, short vertical striae, punctures somewhat sparse, obscured by striations; pubescence of clypeus, moderately long, moderately dense, suberect. Mesosoma dull, coarsely, closely punctate with tessellate granular interspaces; pronotum shinier, transversely tessellate, punctures shallow, separated by one diameter or less, dorsolateral angle absent, without lateral fold; mesoscutum with punctures separated by one diameter, notaulus more or less indistinct; scutellum with punctures separated by leas than one diameter; metanotum rugose-punctate; propodeum rugose-punctate, punctures separated by one diameter or loss, enclosure irregularly rugulose with a median longitudinal carina; episternum 2 rugose-punctate; wing pale, submarginal 1:2 (38:30.5), stigma : rest of marginal cell (25.5:17), hind wing with jugal lobe narrow, without incision between it and vannal, reaching beyond level of cu-v; pubescence long, moderately sparse. Metasoma moderately shiny, moderately coarsely punctate with tessellate interspaces; punctures of first tergum with raised edges, separated by 2 diameters; punctures of terga 2 to 5 separated by 1 to 2 diameters; pubescence of basal elevation of tergum 1 long, erect, of tergum 2 moderately long, erect, of terga 3 to 5 moderately short, suberect; pubescence of depressed margins moderately short, subdepressed, spatulate laterally on terga 2 to 4, forming weak, medially interrupted hair bands, tergum 5 with weak hair band complete. Length 7 to 8 mm, forewing 6 to 7 mm.