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 apparently most closely related to A. cuneilabris. It is readily distinguished from that species and other species of Diandrena by the black integument of the head and mesosoma. The form of the labral processes, dorsolateral angles of the pronotum and jugal lobe of the hind wings in both sexes, and the subapical tooth of the mandibles of the males further distinguish this species from other members of the Chalybaea Group and might warrant placing A. foxii in a separate species group.
Cockerell (1903) assigned A. foxii as one of the original species belonging to his new subgenus Diandrena. This placement was followed until Linsley and MacSwain (1956) transferred it to the subgenus Onagrandrena. These authors suggested that A. foxii "exhibits a number of structural characters of both Diandrena and Onagrandrena." They felt that the "aspect of both sexes" as well as "its biological characteristics" suggested closer affinities with Onagrandrena. Subsequently Linsley and MacSwain (1961b) reassigned A. foxii to Diandrena after studying additional material. They placed greater weight on "the nature of the integumental sculpturing and the presence of only two submarginal cells," while continuing to assert that "The anomalous characters of this species are shared to some extent with both Diandrena and Onagrandrena."
Undoubtedly A. foxii is one of the most distinctive species of Diandrena. However, in addition to the characters weighed by Linsley and MacSwain (1961b), the nest structure, the production of an onion-musk odor, the form of the male genital capsule, and especially the narrowed jugal lobe of the hind wing demonstrate its affinity with Diandrena. Narrowing of the jugal lobe found in 16 species of Diandrena is not known in any other group of Andrena and is possibly the strongest single basis for retaining A. foxii in the subgenus Diandrena.
There is no apparent structural variation in this species other than in size of individuals, and this variation shows no population trends.
FEMALE. — Integument black with bluish tint on metasoma; antenna uniformly black, forewing with stigma dark mahogany to nearly black; pubescence black, anal fimbria dark purple-brown; facial fovea with sheen black, tomentum dark brown on upper two-thirds, light brown on lower third. Head tessellate, densely punctate; clypeus, latero- and supraclypeal areas moderately coarsely, closely punctate with shiny, feebly tessellate interspaces, 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 17: 6: 7; labrum with process bifid (fig. 9); subgenal coronet, moderately long, well developed; gena above moderately coarsely, densely punctate with tessellate interspaces, very fine striae present ventrally; pubescence of clypeus long, moderately dense, suberect. Mesosoma dull, coarsely, moderately closely punctate with dull, tessellate interspaces; pronotum tessellate with punctures separated by one diameter, posterior margin broadly, shallowly emarginate medially, dorsolateral angle rounded with sharp lateral fold; mesoscutum with punctures usually separated by less than one diameter, notaulus long, distinct; scutellum with punctures larger and nearly contiguous; metanotum very dull with large contiguous punctures; propodeum moderately shiny, tessellate-punctate, enclosure longitudinally rugose basally, very finely, transversely striate apically; episternum 2 with tessellate interspaces punctures usually separated by one diameter; wing infuscated, submarginals 1: 2 (21.5:21.5), stigma : rest of marginal cell (20: 28), hind wing with jugal lobe moderately broad and with short, moderately distinct incision between it and vannal, reaching beyond level of cu-v (fig. 87); posterior trochanter with long, curved, black, perfect floccus; tibial scopa long, loose, simple except for narrow band of plumose hairs along inner posterior margin, posterior hairs of scopa about two and one-half times as long as width of tibia at apex; pubescence of mesoscutum black, long and short hairs intermixed. Metasoma shiny, tessellate; first tergum with numerous irregularly spaced, large punctures, separated by 1 to 4 diameters; terga 2 to 4 with punctures smaller and more regularly spaced, separated by about 1 to 2 diameters with tessellate interspaces; pubescence long, erect, sparse, successively shorter on succeeding segments, that of tergum 1 about twice as long as that of tergum 2 and four times as long as that of tergum 3. Length 11 to 12 mm, forewing 8 to 8.5 mm.
MALE. — Integument black with bluish reflections on metasoma, antenna uniformly black, forewing with stigma dark mahogany to nearly black; pubescence dark, black, except white on antennal scape, apex of clypeus, lower gena, vertex, thoracic dorsum, lower part of episternum 2. Head tessellate, densely punctate; clypeus, latero- and supraclypeal areas moderately coarsely, closely punctate with shiny, feebly tessellate interspaces, punctures nearly contiguous; parocular depression short, tear-shaped; eyes with inner margins nearly parallel; antenna with segments 1 to 3 of flagellum as 16: 6; 7.5; labrum with process horseshoe shaped (fig. 10); mandibles long, decussate with subapical tooth flat, thin, translucent; gena dull, moderately coarsely punctate with tessellate interspaces, punctures separated by about one diameter; pubescence of clypeus moderately long, dense, suberect, lower gena with long white hairs. Mesosoma moderately closely, coarsely punctate with dull tessellate interspaces; pronotum tessellate with punctures separated by about one diameter, posterior margin broadly, shallowly emarginate medially, dorsolateral angle rounded, elevated, with lateral fold projecting anteriorly; mesoscutum with punctures usually separated by about one and one-half diameters, notaulus distinct; scutellum and metanotum with punctures usually separated by about one diameter; propodeum moderately shiny, rugose-punctate, enclosure with basal two-thirds regularly, longitudinally rugose, apical third finely granular; episternum 2 coarsely rugose-punctate, puncture's separated by less than one diameter; wing pale, submarginals 1: 2 (19: 21.5), stigma : rest of marginal cell (19: 28), hind wing with jugal lobe moderately broad and with short incision between it and vannal, reaching level of cu-v; pubescence of mesoscutum predominantly long, pale, with few long black and many short black hairs intermixed. Metasoma shiny, tessellate, terga 1 to 5 with punctures moderately coarse and irregularly spaced, separated by about 1 to 4 diameters; sternum 8 (fig. 71); genital capsule (fig. 60); pubescence of tergum 1 about one and one-half times as long as that of tergum 2, and about three times as long as that of segments 3 to 5. Length 7.5 to 10 mm, forewing 7 to 7.5 mm.