Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1973. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VI. Subgenus Trachandrena. Transactions of the American Entomological Society 99: 235-371.
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This small distinctive species is known from just nine females from Nevada and Oregon. It is similar in length of the tergal depressed areas and in the sculpturing of the thoracic dorsum, the propodeum and the terga to A. sigmundi. It differs from females of sigmundi in the dark metasomal vestiture, the dark scopal hairs, the lack of a median impunctate clypeal line, and the slightly narrower upper part (and broader lower part) of the facial foveae. In some respects this bee resembles dark specimens of amphibola, but the pale hairs are white rather than ochraceous or red and the sculpturing is in general much finer. The facial fovea is similar to that of cyanophila.
FEMALE. MEASUREMENTS AND RATIOS. — N = 9; length, 10-11 mm; width, 3.0-3.5 mm; wing length, M = 4.02 ± 0.178 mm; FL/FW, M = 1.12 ± 0.011; FOVL/FOVW, M = 4.24 ± 0.060.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third to half dark rufescent; flagellar segments 3-10 dark blackish-brown; wing membranes hyaline, only slightly infumate, veins dark brown to black; tibial spurs dark reddish-brown.
STRUCTURE. — Antennal scape length slightly shorter than first four flagellar segments; flagellar segment 1 shorter than 2 and 3 together, segment 2 as long as 3 and each shorter than 4, segments 2 and 3 slightly broader than long, 4-9 quadrate. Eyes each about three and three-fourths times as long as broad or slightly longer; inner margins parallel. Malar space and mandible as in sigmundi. Galeae as in sigmundi but dull. Maxillary palpus as in sigmundi but segmental ratio about as 0.9:1.0:0.8:0.8:0.8:0.7. Labial palpus as in sigmundi but ratio about as 1.0:0.7:0.4:0.4. Labrum as in sigmundi. Clypeus as in sigmundi but lacking median impunctate line and small punctures irregular but separated mostly by slightly more than half a puncture width. Supraclypeal area with minute punctures separated mostly by one puncture width, surface shiny. Genal area in profile slightly broader than eye, with deep distinct punctures separated by half a puncture width or less in half near compound eye, posteriorly with fine longitudinal rugulae and interrugal punctures, moderately shiny; ventral surface dull, with fine rugae converging towards mandibles. Vertex above lateral ocellus equals one ocellar diameter or less, moderately shiny, with abundant small punctures and fine reticular shagreening. Face above antennal fossae with coarse punctures separated by half a puncture width or more, without rugae or these poorly formed, surface moderately shiny, delicate reticular shagreening usually present. Facial fovea narrow above, separated from lateral ocellus by three-fourths to one ocellar diameter; lower portion relatively broad, broader than half upper portion and broader than widest space between fovea and compound eye at that level.
Pronotum normal, with abundant punctures dorsally, less abundant laterally, shiny with only delicate shagreening. Mesoscutum, scutellum, metanotum, propodeum and mesepisterna sculptured as in sigmundi but scutellum shiny and posteromedian mesoscutal area shiny. Tibial spurs normal. Venation as in sigmundi.
Metasomal terga 1-4 with apical areas equal to half of each tergum or slightly more; with punctures as in sigmundi except terga 2-4 with basal area punctures slightly more crowded and tergum 1 with basal area punctures sparse as in cyanophila. Pygidial plate as in sigmundi. Sterna densely and finely punctate except narrow apical areas and extreme bases, surfaces dulled by fine reticular shagreening.
VESTITURE. — Head and thorax white except facial foveae vestiture brown and ventral surfaces mesepisterna with brownish-yellow simple hairs. Metasomal vestiture black or dark brown, tergal fasciae absent. Leg hairs black or dark brown except fore and middle coxae usually pale and dorsal femoral hairs often pale.
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