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 quite distinct but shows some affinities to A. macswaini and to the Chalybaea Group. It is distinguished from other species of Diandrena by the dull (opaque) metasomal terga with their coarsely reticulate interspaces.
FEMALE. — Integument grayish-blue, with yellow-green tints on head and propodeum; antenna uniformly dark brownish-black, clypeus with large, dark, subapical triangle with violaceous reflections, forewing with stigma dark brownish-black; pubescence pale, whitish except laterally on face, antennal scape, medially below and above ocelli dark rust-brown, mesosomal dorsum with white and dark rust-brown intermixed, anal fimbria orange-brown, outer surface of tibial scopa white anteriorly, dark rust-brown posteriorly; facial fovea with sheen grayish, tomentum pale brown above, white below. Head dull, tessellate, densely, coarsely punctate; clypeus, latero- and supraclypeal areas with punctures separated by less than one diameter; facial fovea extending from summit of eye to slightly below base of antenna; eye slightly arcuate medially; antenna with segments 1 to 3 of flagellum as 12: 5: 5; labrum with process emarginate, apices pointed, widely separated, shiny (fig. 35); subgenal coronet short, about 5 teeth showing posteriorly; gena tessellate-punctate, punctures moderately fine, separated by about one diameter dorsolaterally, coarser and separated by 1 to 2 diameters posteroventrally, finely striate interspaces posteroventrally; pubescence of clypeus moderately long, sparse, subdepressed. Mesosoma dull, rugose-punctate; pronotum finely, sparsely punctate with transversely tessellate interspaces, punctures separated by 1 to 2 diameters, dorsolateral angle absent, without lateral fold, posterior margin of pronotum transverse; mesoscutum with notaulus indistinct; mesoscutum, scutellum and metanotum rugose-punctate with punctures contiguous and of uniform size; propodeum tessellate, rugose-punctate, enclosure with inner triangle irregularly rugose, lateral and apical borders finely tessellate-granular, with greenish reflections, increasing in width apically; episternum 2 coarsely tessellate-punctate with dorsal edges of punctures raised and with some raised connecting lines giving rugose-punctate appearance anteriorly, tessellate, finely punctate posteriorly; wing lightly infuscated, submarginals 1: 2 (30.5: 35), stigma : rest of marginal cell (14: 21), hind wing with jugal lobe moderately narrow but with distinct incision between it and vannal, reaching slightly beyond level of cu-v; posterior trochanter with long, curved, white, perfect floccus; tibial scopa long, loose, simple except for posterior band of plumose hairs, posterior hairs of scopa about one mid two-thirds as long as width of tibia at apex; pubescence of mesoscutum with few long dark hairs intermixed with numerous short white hairs. Metasoma dull, coarsely tessellate, finely, shallowly, obscurely punctate; punctures of first tergum shallow, shiny, separated by 2 to 4 diameters, punctures of terga 2 to 4 smaller, closer, separated by 1 to 2 diameters; pubescence of tergum 1 moderately long, terga 2 to 4 short erect on basal elevations, with moderately indistinct apical hair bands on terga 3 and 4. Length 7 to 9 mm, forewing 5.5 to 6.5 mm.
MALE. — Integument blue-gray; antenna basally and above dark brownish-black, mahogany below on apical 9 segments, clypeus with narrow subapical dark margin with violaceous reflections, forewing with stigma dark mahogany; pubescence pale, white except laterally on face, antennal scape and few hairs medially on face above and below ocelli purple-brown, anal fimbria rust-brown, thoracic dorsum with yellow and white hairs intermixed. Head moderately shiny, tessellate, densely punctate; clypeus, latero- and supraclypeal areas with punctures contiguous; parocular depression short, linear, with violaceous reflections; eyes slightly convergent below; antenna with segments 1 to 3 of flagellum as 11:7:7.5; labrum with process short, broad, shallowly emarginate apically, strongly recurved (fig. 36); mandibles short, overlapping; gena moderately coarsely punctate, punctures separated by 1 to 2 diameters, with moderately shiny, tessellate, finely, vertically ridged interspaces, finely, longitudinally striate immediately behind mandible, punctures becoming more coarse and sparse ventrally; pubescence of clypeus dense, long, subdepressed. Mesosoma dull, moderately coarsely punctate with tessellate interspaces; pronotum finely, sparsely punctate with transversely tessellate interspaces, dorsolateral angle absent, without lateral fold, posterior margin of pronotum transverse; mesoscutum moderately coarsely, shallowly punctate with punctures separated by one diameter or less, notaulus indistinct; scutellum more or less rugose-punctate with punctures larger and mostly contiguous; metanotum darker, rugose-punctate; propodeum dull, heavily tessellate, enclosure with inner triangle irregularly rugose with median longitudinal carinula, lateral and apical borders finely tessellate-granular, increasing in width apically; episternum 2 coarsely punctate-tessellate anteriorly, with dorsal edges of punctures raised, tessellate, finely punctate posteriorly; wing lightly infuscated, submarginals 1: 2 (30: 34), stigma : rest of marginal cell (13: 21), hind wing with jugal lobe moderately narrow, but with distinct incision between it and vannal, reaching level of cu-v; pubescence of mesoscutum moderately dense, moderately long, of two colors with golden hairs longest. Metasoma dull, moderately coarsely, shallowly, moderately sparsely punctate with tessellate interspaces; terga 1 to 4 with punctures separated by 1 to 2 diameters, punctures less distinct on terga 2 to 4; sternum 8 (fig. 77); genital capsule (fig. 65); pubescence moderately long, erect on terga 1 to 5 becoming shorter on succeeding segments. Length 7 to 8 mm, forewing 5 to 6 mm.