Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1971b. A revision of the bees of the genus Andrena of the Western Hemisphere. Part IV. Scrapteropsis, Xiphandrena, and Rhaphandrena. Transactions of the American Entomological Society 97: 441-520.
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This species is known only in the female sex. It is closely related to A. biareola which it resembles in having a weak pronotal humeral angle and dorsoventral ridge. It is very similar to A. buccata in sculpturing except that the mesepisterna tend to be more coarsely punctate (even punctatorugose) and the mesoscutum with more crowded punctures posteriorly. A. angusticrus, as its name implies, can be distinguished from any of the preceding three species and the one that follows by its narrow middle femora as described below.
FEMALE. MEASUREMENTS AND RATIOS. — N = 15; length, 8-9 mm; width, 2.5-3.5 mm; wing length, M = 3.14 ± 0.133 mm; FL/FW, M = 0.92 ± 0.004; FOVL/FOVW, M = 3.25 ± 0.056.
INTEGUMENTAL COLOR. — Black with the same exceptions as in A. stipator.
STRUCTURE. — Antennal scape length equal to slightly less than flagellar segments 1-4; otherwise antennae as in stipator. Structure and sculpturing of head as in buccata except as follows: maxillary palpus with segmental ratio about 1.0: 1.0: 1.0: 0.8: 0.7: 0.8; labial palpus with ratio about 1.0: 0.7: 0.5: 0.6.
Pronotum with weak humeral angle and weak dorsoventral ridge which extends down to oblique pronotal suture and not much separated from posterior pronotal lobe. Sculpturing of thorax as in buccata except as follows: mesoscutum with short posterior declivity with two or three rows of crowded punctures; mesepisternum largely punctatorugose at least in anterior half and above. Wing venation as in stipator. Legs as in stipator except middle femur slender, at least three times as long as broad.
Metasomal terga sculptured as in buccata. Pygidial plate and sterna as in stipator.
VESTITURE. — In general color and distribution of hairs as in buccata but head with fewer brown hairs or these absent and mesoscutal hairs cinereous.