Reprinted with permission of the American Entomological Society from:
Ribble, D. W. 1974. A revision of the bees of the genus Andrena of the Western Hemisphere. Subgenus Scaphandrena. Transactions of the American Entomological Society 100: 101-189.
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This species is most closely related to A. gordoni in the Pacific northwest of the United States. Like gordoni the female has rather wide facial fovea and spreading tibial scopal hairs. Unlike gordoni the fovea are very dark in color, the body is darker in color and the apical abdominal fasciae are not as well developed. The male can be distinguished from gordoni by the longer antennae and the genitalia (Figs. 44-48).
Males and females of santaclarae have not been collected together but Stone Canyon (2 9 9 ) is within 14 miles of Coalinga (1 male ). It appears as if these males and females of santaclarae belong together. However, the female pterostigmata average slightly larger in size than in the males and the mouthparts are different. The female galeae are shorter and wider with shagreening basally, and the maxillary palpae are shorter and thicker. Andrena tildeni has not been matched with a female and has been collected within about 30 miles of the allotype female of santaclarae. Andrena tildeni appears to be too large, too hairy and to have too coarse of a propodeum to go with the females of santaclarae.
The descriptions below are based mainly upon the allotype and the holotype.
FEMALE. — MEASUREMENTS AND RATIOS. — Length, 9.0 mm; width, 2.6 mm; wing length, 6.8 mm; FL/FW, 0.87; FOVL/FOVW, 2.25.
INTEGUMENTAL COLOR. — As in scurra but hind legs entirely dark.
STRUCTURE. — Antennal scape slightly longer than first four flagellar segments; antenna otherwise as in scurra. Eyes about 3.2 times as long as broad, inner margins as in scurra. Mandible as in scurra. Galea short, pointed, broad, surface shiny with weak shagreening. Stipes with mostly hooked hairs. Labial palpus as in scurra but ratio about 1.0:0.5:0.4:0.5. Maxillary palpus surpassing galea by less than last two segments, segmental ratio about as 1.0:1.0:1.0:1.0:0.7:1.0. Labral process moderate in size, trapezoidal, apex notched, elevated. Clypeus as in scurra but punctures medium-sized, more scattered, obscured by moderate shagreening, duller. Supraclypeal area as in scurra. Face above antennal fossae, vertex and genal area as in scurra but surface dulled by rather coarse reticular shagreening. Facial fovea wide, separated from lateral ocellus by one and one-half ocellar diameters, length as in scurra.
Pronotum as in scurra but punctures obscured by moderate shagreening. Mesoscutum as in scurra but entire surface with punctures obscured by rather coarse reticular shagreening, punctures further apart. Scutellum sculptured as mesoscutum. Propodeum with dorsal area triangular with coarse but regular shagreening; remainder of propodeum as in scurra but shagreening on dorsolateral and posterior surfaces smoother and regular. Mesepisternum as in scurra but surface with coarse reticular shagreening. Wings as in scurra but pterostigma slightly larger. Legs as in scurra.
Metasomal terga 1-4 as in scurra but punctures fewer, indistinct. Tergum 5 with medium-sized punctures, reticular shagreened. Pygidial plate as in scurra. Sterna 2-5 as in scurra but punctures not as close.
VESTITURE. — Generally white otherwise as in scurra except as follows: hairs less abundant; facial fovea dark brown to black, hind tibia at base, hind femur at apex, tip of abdomen with amber hairs; hind tibia with hairs along anterior margin mostly curved anteriorly, surface of tibia easily visible; metasomal terga 2-4 with moderately well developed apical white fasciae, on terga 2 and 3 incomplete medially.
MALE. — MEASUREMENTS AND RATIOS. — Length, 6.5 mm; width, 1.8 mm; wing length, 5.4 mm; FL/FW, 1.00; FS1/FS2, 0.86.
INTEGUMENTAL COLOR. — Color as in scurra except clypeus lighter yellow, legs entirely dark.
STRUCTURE. — Antenna long, reaching posterior part of propodeum; scape length about equal to first two and one-third flagellar segments; flagellar segment 1 as long as segment 2, segment 2 shorter than 3, segments 2-11 much longer than broad. Eyes each about 3.7 times as long as broad, inner margins as in scurra. Mandible as in scurra. Galea as in female but not as broad, basally without shagreening, very shiny. Stipes with few long straight hairs. Labial palpus as in scurra but ratio about 1.0:0.5:0.4:0.5. Maxillary palpus as in scurra but ratio about 0.9:0.9:0.9:1.0:0.6:0.7. Labrum as in female but process emarginate at apex. Clypeus as in female but shagreening weak, flattened area basally. Supraclypeal area, face above antennal fossae, vertex and genal area as in female.
Pronotum, mesoscutum, scutellum and mesepisternum as in female. Wings as in female scurra. Legs as in scurra but hind tibia slender.
Metasomal terga 1-4 as in female but apicolateral elevations weakly developed. Tergum 5 with small punctures, reticular shagreening. Sterna 2-5 as in female but punctures more scattered. Sternum 6 as in scurra.
Terminalia as in figures 44-48; note the following: gonocoxite with dorsal lobes short and broadly rounded, apex rather broad, emarginate on inner margin; penis valve broad basally, without dorsal lamellae, apex long, slender, bent posteriorly; sternum 7 with large apical notch; sternum 8 with apex slightly broader than neck region, apex distinctly emarginate.
VESTITURE. — Generally white, hairs otherwise as in scurra except less abundant; few dark hairs on face; center of tergum 2 with few longer hairs; apical abdominal fasciae weakly developed on terga 2 and 3, reduced to a few scattered hairs laterally; weak but complete on tergum 4.
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