Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1980. A revision of the bees of the genus Andrena of the Western Hemisphere. Part X. Subgenus Andrena. Transactions of the American Entomological Society 106: 395-526.
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This moderate-sized bee is very similar to A. buckelli Viereck from which it differs in both sexes by having the clypeus dulled by reticular shagreening or fine tessellation in the posterior third or more and the shorter vertex as described below; The female of saccata has the labral process flattened basally (not sulcate as in buckelli and vicinoides) and the male has the tips of the penis valves compressed (not expanded and blunt as in buckelli); Both sexes differ from vicinoides (and are similar to buckelli) in lacking the basal inferior mandibular teeth.
Andrena saccata occurs at lower elevations of the West Coast and overlaps the range of buckelli only slightly; However, a few specimens from montane regions of California and Oregon appear to be typical saccata and a few specimens from coastal areas of California, Oregon and Washington appear to by typical buckelli, indicating that distinct species are involved rather than geographic races.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 10-13 mm; width, 3.0-3.5 mm; wing length, M = 4.50 ± 0.149 mm; FL/FW, M = 0.92 ± 0.006; FOVL/FOVW, M = 2.94 ± 0.044.
INTEGUMENTAL COLOR. — As in vicinoides but flagellar segments below usually dark brown and tibial spurs testaceous.
STRUCTURE. — Antennal scape slightly shorter than first three flagellar segments together; flagellar segments as in vicinoides; Eyes each about four times as long as broad, inner margins parallel; Mandible as in vicinoides but without basal inferior angle or tooth; Malar space and galea as in vicinoides; Maxillary palpus as in vicinoides but segmental ratio about as 1.0:1.0:0.8:0.8:0.7:0.6; Labial palpus as in vicinoides but ratio about as 1.0:0.6:0.4:0.4; Labral process large, square in outline or trapezoidal, bidentate, slightly reflexed apically, flat basally (without transverse basal sulcus); labrum below process as in vicinoides; Clypeus as in vicinoides but median impunctate line often complete and surface dulled by fine reticular shagreening in basal third or more and laterally, usually entirely dulled except small apicomedian area moderately shiny; Supraclypeal area, face above antennal fossae and facial fovea as in vicinoides; Vertex as in vicinoides but usually short, above lateral ocellus usually equal to slightly less than one ocellar diameter and never more; Genal area as in vicinoides; Thoracic form and sculpturing as in vicinoides; Wing venation as for subgenus, second submarginal cell usually about as long as broad.
Metasomal terga, sterna and pygidial plate as in vicinoides; tergum 2 with apical area short (medially no longer than one-third tergal length).
VESTITURE. — Generally as in dark specimens of vicinoides with dark head, metasoma, pleura and legs and pale thoracic dorsum; tergum 1 usually with dark hairs, occasionally ochraceous; tergum 2 rarely with ochraceous hairs mediobasally; Pollen-collecting hairs as in vicinoides.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-11 mm; width, 2.0-2.5 mm; wing length, M = 3.75 ± 0.227 mm; FL/FW, M = 0.90 ± 0.008; FS1/FS2, M = 0.95 ± 0.012.
INTEGUMENTAL COLOR. — As in vicinoides but flagellar segments below dark brown and tibial spurs testaceous.
STRUCTURE. — Antennae as in vicinoides but flagellar segment 1 often slightly shorter than segment 2, rarely slightly longer; Eyes each three and one-half times as long as broad or slightly shorter, inner margins parallel; Mandibles as in vicinoides but without basal inferior tooth; Malar space and galea as in vicinoides; Maxillary palpus as in vicinoides but segmental ratio about as 0.9:1.0:0.9:0.9:0.8:0.8; Labial palpus as in vicinoides but ratio about as 1.0:0.6:0.6:0.6; Labrum as in vicinoides; Clypeus as in vicinoides but surface dulled by fine reticular shagreening in basal third or more and laterally, usually dulled except small apicomedian, shiny to moderately shiny area; Supraclypeal area, face above antennal fossae and genal area as in vicinoides; Vertex as in female; Thoracic form and sculpturing as in vicinoides; propodeal dorsal area often with weak irregular rugulae in basal half or less; Wing venation as in female.
Metasomal terga and sterna as in vicinoides; sternum 6 abruptly reflexed apically.
Terminalia as in figures 152-156; note penis valves with tips compressed (not expanded and blunt as in buckelli).
VESTITURE. — Generally as in vicinoides but face and clypeus usually with ochraceous hairs at least medially; tergum 2 often with pale hairs basally; tergum 3 without pale hairs.