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. subapasta and is distinguished from that species by its larger size, darker and more bluish integument, broader jugal lobe of the hind wing with an incision between it and the vannal lobe, and broader and more feebly emarginate apex of the labral process.
There is a clinal tendency toward lighter and more greenish integument in individuals from populations north of San Luis Obispo County. This species is an oligolege of yellow-flowered, morning-opening species of Camissonia, and apparently reaches its maximum population abundance in San Luis Obispo County.
FEMALE. — Integument dark blue; antenna uniformly dark brownish-black, forewing with stigma dark brown, clypeus with narrow, transverse, subapical dark band with violaceous reflections; pubescence dark, black on head with some pale brown on summit of vertex, black on thoracic pleura, pale brown on dorsum of thorax, black on legs except pale brown on basitarsi and scopa of posterior tibia grading to dark brown on posterior of scopa, floccus gray, metasoma with hair pale brown, anal fimbria dark gray-brown; facial fovea with black sheen, tomentum dark brown. Head moderately shiny, coarsely, closely punctate with tessellate interspaces; clypeus, latero- and supraclypeal areas with punctures nearly contiguous; 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 14:5.5:5.5; labrum with process broadly rectangular, weakly emarginate apically (fig. 51); subgenal coronet short, black, moderately well developed; gena moderately dull, tessellate, finely, vertically striate, with fine, sparse punctures obscured by striations; punctures separated by about 2 diameters; pubescence of clypeus moderately long, moderately sparse, suberect. Mesosoma moderately dull, coarsely, deeply punctate with tessellate-granular interspaces; pronotum moderately shiny, finely, sparsely punctate with finely granular interspaces, punctures separated by 2 to 4 diameters, dorsolateral angle absent., without, lateral fold; mesoscutum with punctures separated by slightly more than one diameter, notaulus short, fine, somewhat obscure; scutellum shinier medially, punctures larger, separated by slightly less than one diameter; metanotum tending toward rugose-punctate condition; propodeum rugose-punctate, enclosure irregularly rugulose with fine longitudinal median carinula; episternum 2 rugose-punctate; wing lightly infuscated, submarginals 1:2 (21.5:19), stigma : rest of marginal cell (19:25.5), hind wing with jugal lobe somewhat broad and with incision between it and vannal, reaching level of cu-v; posterior trochanter with long, curved, gray, perfect floccus; tibial scopa with long, moderately sparse, simple hairs except for narrow band of branched hairs along posterior margin, posterior scopal hairs twice as long as width of tibia at apex; pubescence of mesoscutum moderately dense, predominantly black laterally, with long pale brown and moderately long black hairs intermixed centrally. Metasoma moderately dull, moderately finely, sparsely punctate with granular interspaces; first tergum with punctures moderately coarse, separated by 2 to 4 diameters; terga. 2 to 4 with punctures finer, separated by 2 to 3 diameters; pubescence of tergum 1 long, erect, of tergum 2 one-third length of tergum 1, shorter, suberect on terga 3 and 4. Length 8 to 10 mm, forewing 7 to 8.5 mm.
MALE. — Integument olive-green with bluish reflections on pleura, propodeum and apical depressed margins of metasomal terga; antenna uniformly dark brownish-black, stigma dark brownish-black, clypeus with narrow, linear, subapical, dark band with violaceous reflections; pubescence pale, white except golden on anal fimbria, black laterally on face, above and behind eye, black and white intermixed on upper half of episternum 2. Head moderately shiny, coarsely, closely punctate with tessellate interspaces; clypeus, latero- and supraclypeal areas with punctures nearly contiguous; parocular depression elongate, linear; eyes convergent below; antenna with segments 1 to 3 of flagellum as 12:5;9; labrum with process short, broad, shallowly emarginate apically (fig. 52); mandibles moderately short, somewhat decussate; gena moderately dull, tessellate, finely, more or less vertically striate, punctures sparse, obscured by striations; pubescence of clypeus long, dense, subdepressed. Mesosoma dull, coarsely, deeply punctate with granular interspaces; pronotum with punctures shallow, sparse, separated by 2 to 3 diameters, dorsolateral angle absent, without lateral fold; mesoscutum with punctures separated by 1 to 2 diameters; notaulus indistinct; scutellum shinier anteriorly with punctures separated by one diameter, posteriorly with punctures closer; metanotum with punctures shallow more or loss rugose-punctate; propodeum rugose-punctate, enclosure irregularly rugulose with fine, longitudinal median carinula; episternum 2 rugose-punctate with punctures more separated below; wing pale, submarginals 1:2 (31.5:32.5), stigma : rest of marginal cell (35:22), hind wing with jugal lobe moderately broad and with incision between it and vannal, reaching level of cu-v; pubescence long, sparse. Metasoma moderately dull, moderately coarsely, sparsely punctilio with granular interspaces; first tergum with punctures separated by 2 to 3 diameters, terga 2 to 5 with punctures finer, separated by 2 diameters, punctures shallower, sparse on depressed apical margins of terga 1 to 5; pubescence long and erect on basal elevations of terga 1 and 2, moderately long, suberect on basal elevations of terga 3 to 5, subdepressed on apical depressed margins. Length 7 to 8 mm, forewing 6 to 6.5 mm.