Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1985. A revision of the bees of the genus Andrena of the Western Hemisphere. Part XI. Minor subgenera and subgeneric key. Transactions of the American Entomological Society 111: 440-567.
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This species can be readily separated from angustella by the more punctate clypeus and shinier galeae and terga in both sexes and by the basal inferior tooth of the mandibles of males; female also has the hind tibial scopal hairs brown along the posterior margin of the tibia.
female: MEASUREMENTS AND RATIOS: N = 20; length, 9-11 mm; width, 2.5-3.5 mm; wing length, M=4.05±0.134 mm; FL/FW, M=0.84± 0.032; FOVL/FOVW, M=2.59±0.089
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical half or less rufescent; flagellum below dark brown to black; wing membranes slightly infumate, yellow, veins dark reddish brown to black; terga with apical areas translucent, yellow to rufescent; sterna 2-5 with apical areas translucent, yellow tibial spurs testaceous.
STRUCTURE. — Scape length equals first three and one-half flagellar segments; flagellar segment 1 slightly shorter than segment 2 plus 3; segment 2 about as long as segment 3, as long as broad; segments 4-9 longer than broad. Eyes each about three and one-half times as long as broad, inner margins parallel to converging slightly toward vertex. Malar space moderate, minimum length equals about one-fifth of basal mandibular width. Mandible when closed surpasses midlabrum by less than one-fifth its own length; with subapical tooth. Galea as in angustella but shiny, shagreening extremely weak to absent. Maxillary palpus as in angustella, but segmental ratio about 0.8:1.0:0.7:0.7:0.6:0.5. Labial palpus as in angustella, but ratio about 1.0:0.5:0.5:0.5. Labral process entire, short, three to four times as broad as long, shorter than apical part of labrum; labrum apical to process with a transverse sulcus crossed by several weak cristae. Clypeus relatively flat, broad; punctures of irregular size, separated by one to two puncture widths except along broad impunctate midline and extreme lateral angles with more crowded, smaller punctures; surface shiny apicomedially to dull basally and laterally, shagreened. Supraclypeal area and face above antennal fossae as in angustella. Facial fovea as in angustella but separated from lateral ocellus by about one ocellar diameter. Vertex and genal area as in angustella.
Thoracic form and sculpturing as in angustella, but scutellum often moderately shiny, shagreening weak. Fore wing with vein 1st m-cu meeting second submarginal cell in outer one-fifth to one-fourth of cell.
Metasomal tergum 1 dull, tessellate with scattered small punctures. Terga 2-5 with apical areas dull, tessellate; basal areas moderately shiny to shiny, weakly shagreened especially basally or not at all shagreened; punctures small, distinct, separated mostly by two and to three puncture widths. Pygidial plate V-shaped with rounded apex and raised internal triangular area. Sterna 2-5 as in angustella.
VESTITURE. — White except as follows: facial foveae with short dark brown hairs; vertex, upper ends of genal area, most of face above antennal fossae dark brown; mesoscutum posteromedially and scutellum medially with dark brown hairs or dark hairs mixed with pale; terga 3-4 with basal areas dark brown; terga 5 and 6 dark brown; basitibial plate, end of femur above plate, and posterior half or less of tibial scopal hairs dark brown; tarsi brown on outer surfaces or brown in part; outer surfaces middle and fore tibiae brown. Propodeal corbiculum complete anteriorly, interior bare or with few to several, long, weakly branched hairs; trochanteral flocculus complete, full; hind tibia with scopal hairs abundant, long, simple. Terga 2-4 with complete apical white fasciae; tergum 1 with weak apical pale fascia.
male: MEASUREMENTS AND RATIOS: N = 7; length, 6-8 mm; width, 1.5-2.0 mm; wing length, M= 3.31 ±0.193 mm; FL/FW, M=0.87± 0.079; FS1/FS2, M(6)=0.89±0.116.
INTEGUMENTAL COLOR. — Black except as follows: clypeus yellow except apical margin, extreme lateral angles, and posterior third to half; mandible with apical third or less rufescent; otherwise exceptions as in female.
STRUCTURE. — Antennae moderately long; scape length equals first two and one-third flagellar segments or less; flagellar segment 1 slightly shorter than segment 2; segment 2 subequal to 3; segments 2-10 considerably longer than broad. Eyes each about three and one-fourth times as long as broad, inner margins diverging slightly toward vertex. Malar space and galeae as in female. Mandibles decussate, with small subapical teeth, with basal inferior teeth. Maxillary palpus as in female, but segmental ratio about 0.9:1.0:0.9:0.9:0.6:0.6. Labial palpus as in female, but ratio about 1.0:0.6:0.6:0.6. Labrum as in angustella. Clypeus flat, punctures distinct, in median third to half separated mostly by two to four puncture widths, more crowded laterally; surface finely shagreened near base and laterally. Supraclypeal area as in angustella. Face above antennal fossae as in angustella, but rugulae shorter, not reaching ocelli, face tessellate below ocelli. Vertex and genal area as in angustella.
Thoracic form and sculpturing as in female; wing venation as in female, but vein 1st m-cu meets second submarginal cell at middle of cell or just beyond middle.
Metasomal terga 1-5 sculptured as in female terga 1-4, but terga 2 and 3 often not at all or only moderately shiny, reticularly shagreened. Tergum 7 without pygidial plate. Sterna 2-5 as in angustella. Terminalia (Figs. 59-63) similar to those of angustella, but penis valves with tips acute and sternum 8 with apical margin entire and neck region narrower.
VESTITURE. — Pale ochraceous to white except as follows: face above antennal fossae, alongside of compound eyes, vertex, and upper half or less of genal area with long dark brown hairs; mesoscutum and scutellum with long dark hairs mixed with the pale; terga 3-5 or 4-5 often with basal area hairs brown; terminal terga yellow to yellow brown; inner surfaces tarsi pale yellow. Terga 2-4 with weak apical fasciae usually present; sterna 2-5 without subapical pale fimbriae, hairs long.
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