Reprinted with permission of the American Entomological Society from:
Bouseman, J. K., LaBerge, W. E. 1978. A revision of the bees of the genus Andrena of the Western Hemisphere. Part IX. Subgenus Melandrena. Transactions of the American Entomological Society 104: 275-390.
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This small western species is distinctive in the dark terga, pale scopal hairs and usually bright yellow to red thoracic dorsum. Both sexes have weakly sculptured metasomal terga with relatively distinct blue-green metallic reflections (often lacking in the males). The female lacks the median clypeal impunctate line and the male has a notably short clypeus.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 10-12 mm; width, 3.0-3.5 mm; wing length, M = 4.26 ± 0.160 mm; FL/FW, M a 0.89 ± 0.005; FOVL/FOVW, M = 3,42 ± 0.049.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third to half dark rufescent; flagellar segments below dark brown to dark reddish-brown; tegula dark, slightly translucent; wing membranes moderately infumate, brownish, veins dark brown; terga usually with blue-green metallic reflections, rarely with dark rufescent reflections; sterna often with dark rufescent reflections basally; tibial spurs dark brown to reddish-brown.
STRUCTURE. — Antennal scape length equal to first three and three-fourths flagellar segments; flagellar segment 1 as long as segments 2 plus 3 or slightly shorter; segment 2 shorter than 3, broader than long; segment 3 shorter than 4, quadrate; segments 4-10 longer than broad. Eyes each about three and one-half times as long as broad, inner margins parallel. Mandible as in carlini. Galea as in carlini but shiny, shagreening absent or extremely weak. Maxillary palpus as in carlini but segmental ratio about as 0.9:1.0:0.8:0.8:0.6:0.6. Labial palpus as in carlini but ratio about as 1.0:0.8:0.7:0.7. Labral process entire, moderately shiny, usually trapezoidal; labrum apical to process with strong median crista usually present, sulci on either side of crista dulled by short cristae. Clypeus with round punctures separated by a half a puncture width or slightly more, becoming small and obscure in posterior fourth; with median impunctate line absent or restricted to apical half of clypeus or less; surface shiny except posteriorly where finely shagreened. Supraclypeal area extremely finely punctate and shagreened. Face above antennal fossae with fine longitudinal rugulae and weak interrugal punctures dulling surface. Facial fovea as in carlini but separated from lateral ocellus by one or more ocellar diameters. Vertex above lateral ocellus relatively short, equal to about one and one-third ocellar diameters, surface dull, tessellate. Genal area as in carlini.
Thoracic form and sculpturing as in carlini except as follows: mesoscutal punctures minute, separated mostly by two puncture widths or more; scutellum similar; propodeal dorsal enclosure tessellate, not roughened basally, lateral surface without vermiculate rugulae posteriorly. Wing venation as in carlini but pterostigma about as broad as from inner margin prestigma to wing margin and second submarginal cell not usually markedly narrowed along anterior margin.
metasomal terga with punctures minute, shallow, surfaces dulled by fine reticular shagreening; tergum 2 with basal area punctures separated mostly by one to two or more puncture widths. Pygidial plate V-shaped with apex acute unless worn. Sterna sculptured as in carlini but punctures dense in apical half of each sternum except in narrow apical rim.
VESTITURE. — Head hairs white to ochraceous, usually yellow to fox-red on vertex; facial fovea with short hairs dark brown at least in upper half; vertex with few dark brown hairs. Thoracic hairs white below and laterally, yellow to fox-red above. Metasomal tergal hair brown to dark brown except tergum 1 usually white and long lateral hairs of terga 2-6 often white. Sternal hairs brown except some long subapical hairs laterally white. Leg hairs dark brown except as follows: white to pale ochraceous on hind trochanter, all femora, outer surface midtibia at least basally, and outer surface hind tibia (but often dark brown from basitibial plate to apex along middle of surface, pale anteriorly and posteriorly); rarely dark brown on posterior surface hind tibia.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-10 mm; width, 2.0-2.5 mm; wing length, M = 3.62 ± 0.216 mm; FL/FW, M = 0.80 ± 0.008; FS1/FS2, M = 1.18 0.016.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third or more dark rufescent; flagellar segments 3-11 dark reddish-brown below; tegula dark reddish-brown, slightly translucent; wing membranes hyaline, slightly infumate, veins reddish-brown; terga with apical areas translucent, yellow to brown, basally often with rufescent reflections, occasionally with slight metallic reflections; sterna with apical margins hyaline, basally with rufescent reflections; distitarsi dark rufescent; tibial spurs testaceous to red.
STRUCTURE. — Antennal scape length equals first two and three-fourths flagellar segments; flagellar segment 1 usually slightly longer than segment 2 which is quadrate or slightly longer than broad and shorter than segment 3; segments 3-10 about one and one-fourth times as long as broad or slightly longer. Eyes each about one and one-third times as long as broad, inner margins diverging slightly toward mandibles. Mandible long, slightly decussate as in carlini. Galea as in female. Maxillary palpus as in carlini but segmental ratio about as 0.9:1.0:0.8:0.8:0.6:0.6. Labial palpus as in carlini but ratio about as 1.0:0.7:0.5:0.6. Labral process large, flat, shiny, trapezoidal, occasionally with slightly apical emargination; labrum apical to process minutely punctate, shiny, without crista or sulci. Clypeus exceptionally short, median length usually equals slightly less than one-third minimum interocular distance and never more; surface dulled by crowded small punctures and reticular shagreening. Supraclypeal area, face above antennal fossae and vertex as in female. Genal area as in carlini.
Thoracic form and sculpturing as in female. Wing venation as in female but second submarginal cell occasionally receiving vein 1st m-cu beyond middle of cell.
Metasomal terga 2-5 sculptured as in female but punctures sparser and surface slightly shinier. Tergum 7 with pygidial area extremely narrow and pointed. Sterna 2-5 sculptured as in carlini. Sternum 6 with apical margin turned down and shallowly emarginate, without triangular raised area subapically. Terminalia as in figures 18-22; sternum 8 as in carlini in lateral view.
VESTITURE. — Generally pale ochraceous except as follows: vertex occasionally with some brown hairs; dorsum of thorax with long hairs often yellow to dull red; terga 2-5 often with sparse short hairs reddish-brown; inner surfaces hind basitarsi pale yellow. clypeal beard long and dense; dorsal thoracic hairs long and sparse; terga without apical fasciae; sterna without apical fimbriae.