Reprinted with permission of the American Entomological Society from:
LaBerge, W. E., Ribble, D. W. 1975. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VII. Subgenus Euandrena. Transactions of the American Entomological Society 101: 371-446.
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This interesting species is an annectant form between the Euandrena on one hand and the Thysandrena complex on the other hand. Some of the characteristics of subdepressa, such as the punctate clypeus, ally it with the Thysandrena, however the narrow vannal lobe of the hind wing clearly relates subdepressa to misella and suavis of the Euandrena. It seems unlikely that this character arose more than once in this complex of the Andrena.
Among the Euandrena, the female of subdepressa is marked by the distinctly flattened clypeus with deep round punctures. The labral process is relatively short, as in misella, and the pygidial plate is flat, as in misella. The male of subdepressa can be told from that of misella or suavis only with great difficulty. Like misella the male has thin tergal bands often interrupted medially, but the integument of the head and thorax is faintly metallic as in suavis (although the metallic sheen of subdepressa is normally deep blackish-blue rather than bluish-green or green). The male of subdepressa usually has a more distinctly punctate clypeus and a longer head than either misella or suavis.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-10 mm; width, 2.5-3.0 mm; wing length, M = 3.49 ± 0.098 mm; FL/FW, M = 0.98 ± 0.005; FOVL/FOVW, M = 4.76 ± 0.078.
INTEGUMENTAL COLOR. — Black, usually with extremely faint, dark blackish-blue, metallic reflections; clypeus without violaceous reflections. Mandible, antenna, wings as in caerulea. Legs black or dark brown. Terga with apical areas broadly smoky or translucent.
STRUCTURE. — Antennal scape about as long as first three and one-half flagellar segments; antenna otherwise as in caerulea. Eyes each more than four times as long as broad, inner margins nearly parallel. Mandible and galea as in ciu'nili'11. Maxillary palpus as in caerulea but segmental ratio about as 1.0:1.0:0.9:0.9:0.8:0.9. Lahi.il palpus as in caerulea but ratio about as 1.0:1.0:0.7:1.0. Labral process rectangular, short and wide, usually two and one-halt' times as broad as long or broader, rarely slightly emarginate apically; labrum below process shiny, without median crista. Clypeus long, much flattened (subdepressed) medially, with distinct round punctures separated mostly by one-half to one puncture width (sparser along midline especially in basal half), usually surface dulled by fine reticular shagreening especially in basal half. Supraclypeal area dulled by minute crowded punctures. Face above antennal fossae dulled by moderately coarse, longitudinal rugulae (coarser than in caerulea or suavis) and fine interrugal punctures. Facial fovea small, narrow, much as in caerulea, Vertex and genal area as in caerulea.
Thoracic sculpturing and structure as in caerulea except as follows: hind wing with vannal lobe narrow (as in misella), at excision about as broad as end of cell Cu; hind tibia normal, not broadened nor cuneate.
Metasomal terga as in caerulea but punctures of basal areas (especially of terga 1 and 2) more distinct (as in misella). Pygidial plate flat, broad, rounded or blunt at apex, without raised internal ridge, edges occasionally upturned (much as in misella). Sterna as in caerulea.
VESTITURE. — Generally white with the following exceptions: face along inner margins compound eyes and above antennal fossae usually black; vertex black; foveae with short black hairs; mesepisternum with upper part usually with black mixed with pale; dorsum of thorax ochraceous; terga 5 and 6 brown at least medially; hind legs with brown hairs on and sur-rounding basitibial plates and often along posterior margins of scopae; inner surfaces tarsi yellow. Terga 1 and 2 and basal areas of 3 and 4 with erect long hair (as in misella); terga 2-4 with pale apical fasciae present but narrow and often narrowly interrupted medially on tergum 2 and occasionally on tergum 3. Pollen-collecting hairs as in misella but scopal hairs always simple at least medially.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7-8 mm; width, 1.5-2.0 mm; wing length, M = 2.94 ± 0.121 mm; FL/FW, M = 1.00 ± 0.007; FS1/FS2, M = 1.86 ± 0.034.
INTEGUMENTAL COLOR. — Black except as follows: face and thorax with dark, blackish-blue, metallic reflections; mandible with tip rufescent; flagellum black or blackish-brown below; wings, metasoma and legs as in female.
STRUCTURE. — Antenna moderately long, reaching metanotum in repose; scape length about equal to first two and one-half flagellar segments; flagellar segments as in caerulea. Eyes each slightly less than four times as long as broad, inner margins strongly converging towards mandibles. Mandible and galea as in caerulea. Maxillary palpus as in caerulea but segmental ratio about as 0.9:1.0:0.9:0.9:0.7:0.9. Labial palpus as in caerulea but ratio about as 1.0:0.7:0.6:0.7. Labrum as in female but process usually slightly longer and often broadly and gently emarginate apicomedially. Clypeus, supraclypeal area, face above antennae, vertex and genal area as in caerulea.
Thoracic structure and sculpturing as in female but propodeum outside of enclosure and mesepisternum with more distinct punctures.
Metasomal sculpturing as in female but basal area punctures less evident.
Terminalia as in figures 50-54; note the following: gonostylus narrowed at apex; dorsal lobe gonocoxite broad, rounded; sternum 7 deeply emarginate apically.
VESTITURE. — Generally as in female but dark hairs usually more abundant on head and thorax and metasomal terga 2-5 with pale apical bands usually at least narrowly interrupted medially; sterna with subapical fimbriae absent or extremely weak.
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