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 exhibits some degree of relationship to all species in the Chalybioides Group, but is apparently most closely related to the A. anatolis-A. eothina line. It is distinguished from those species by its larger size, the more deeply emarginate apex of the labral process, and in the females by the branched and denser hairs of the tibial scopa. This species is not common in collections and remains poorly known ecologically. It is the only species of Diandrena which has not been found in California. Michener (1937) records this species from Hayden, Routt County, Colorado, but since I have not seen this specimen, it has not been included on the map or in the discussion of distribution.
FEMALE. — Integument blue-green with golden reflections; antenna dark brownish-black basally and above apically, yellow-brown below on apical 6 to 7 flagellar segments; forewing with stigma yellow-brown, clypeus with moderately narrow, subapical, dark band with violaceous reflections; pubescence pale, white except dark brown laterally on face, above and behind eye, and on anal fimbria, dark brown and white intermixed on clypeus, outer face of tibial scopa white anteriorly, dark brown on posterior third; facial fovea with sheen black, tomentum white below, chocolate-brown above. Head moderately shiny, coarsely, closely punctate with tessellate interspaces; clypeus with punctures separated by one diameter or less; latero- and supraclypeal areas with punctures nearly contiguous and shallow; facial fovea extending from summit of eye to middle of antennal base; eye slightly arcuate medially; antenna with segments 1 to 3 of flagellum as 14:5:5; labrum with process elongate, deeply emarginate with apices divergent (fig. 29); subgenal coronet long, well developed; gena moderately shiny, tessellate, moderately coarsely punctate, punctures separated by about 2 diameters; pubescence of clypeus moderately long, sparse, suberect. Mesosoma dull, closely, moderately coarsely, shallowly punctate with tessellate interspaces; pronotum moderately shiny, tessellate anteriorly, dull, transversely tessellate posteriorly, punctures shallow, moderately coarse, sparse, dorsolateral angle obtusely angled with short lateral fold, posterior margin of pronotum nearly transverse; mesoscutum with punctures separated by one diameter or less, peripherally and along midline with edges of punctures raised and tessellations more sparse, lateromedially edges of punctures not raised and tessellations more dense, notaulus distinct; scutellum rugose-punctate peripherally and along midline, separated by less than one diameter antero- and lateromedially; metanotum rugose-punctate; propodeum rugose-punctate, enclosure with inner triangle with somewhat regularly longitudinal rugosities basally becoming irregularly rugose apically, lateral edges with rugae becoming less distinct, apical edge transversely striate; episternum 2 rugose-punctate anteriorly, finely striate-punctate posteriorly; wing pale, submarginals 1: 2 (35: 39.5), stigma : rest of marginal cell (16: 24), hind wing with jugal lobe narrow and without incision between it and vannal, reaching level of cu-v; posterior trochanter with long, curved, white, perfect floccus; tibial scopa long, dense, with hairs of posterior half of outer face branched, posterior hairs of scopa twice as long as width of tibia at apex; pubescence of mesoscutum with moderately long and moderately short hairs intermixed. Metasoma dull, finely sparsely punctate with tessellate interspaces; punctures of first tergum with edges raised, separated by 2 to 3 diameters, terga 2 to 4 with punctures indistinct; pubescence moderately long, suberect. Length 8 to 9 mm, forewing 6.5 to 7.5 mm.
MALE. — Integument blue-green with yellow-green reflections centrally on clypeus, on vertex, centrally on thoracic dorsum, greenish on basal elevations of metasomal terga 2 to 5, violaceous depressed apical margins of terga 1 to 5; antenna uniformly black, forewing with stigma yellowish-brown, clypeus with subapical, transverse dark line with violaceous reflections; pubescence pale, white except black laterally on face, above and behind eye, golden on anal fimbria. Head shiny, coarsely, densely punctate; punctures of clypeus separated by less than one diameter; parocular depression very short, linear; eyes slightly convergent below; antenna with segments 1 to 3 of flagellum as 13:5:7; labrum with process strongly recurved and deeply; emarginate apically (fig. 30); mandibles moderately long, decussate; gena moderately shiny, tessellate, laterally with fine vertical striae, moderately finely punctate with punctures separated by 1 to 2 diameters, ventroposteriorly more coarsely striate-punctate; pubescence of clypeus moderately long, sparse, subdepressed. Mesosoma moderately dull, coarsely, moderately closely, shallowly punctate with tessellate interspaces; pronotum moderately shiny, punctures separated by 1 to 2 diameters with tessellate interspaces, dorsolateral angle somewhat right-angled with moderately distinct lateral fold, posterior edge of pronotum slightly arched; mesoscutum with surface duller with punctures separated by less than one to slightly more than one diameter, notaulus moderately distinct, parapsidal line elevated; scutellum with punctures contiguous along midline and lateral and posterior edges; metanotum rugose-punctate; propodeum rugose-punctate, enclosure with inner triangle with somewhat regularly longitudinal rugosities basally, becoming irregular apically, laterally with rugosities becoming less distinct, apically transversely striate; episternum 2 coarsely punctate with tessellate interspaces, punctures with dorsal edges produced, separated by one diameter; wing pale, submarginals 1:2 (31.5:30), stigma; rest of marginal cell (14: 20), hind wing with jugal lobe very narrow and without incision between it and vannal, reaching level of cu-v; pubescence of mesoscutum long, sparse. Metasoma moderately dull, depressed margins of terga shinier, moderately finely, shallowly, sparsely punctate with tessellate interspaces, tessellation more dense on basal elevations; punctures of first tergum separated by 2 to 3 diameters; terga 2 to 5 with fine, more or less indistinct punctate on basal elevations, separated by 1 to 2 diameters; pubescence long, suberect on tergum 1, about one-third as long, suberect on terga 2 to 5. Length 6.5 to 7 mm, forewing 5.5 to 6 mm.