Reprinted with permission of the American Entomological Society from:
LaBerge, W. E., Ribble, D. W. 1972. A revision of the bees of the genus Andrena of the Western Hemisphere. Part V: Gonandrena, Geissandrena, Parandrena, Pelicandrena. Transactions of the American Entomological Society 98: 271-358.
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This small species of the southern great plains area (Fig. 7) is closely related to A. andrenoides. The female of arenicola is like that of wellesleyana and unlike that of andrenoides or nida in terga 2-4 having complete apical bands, in the shape of the clypeus and in tergum 2 having long hairs medially. The male of arenicola is like that of andrenoides in having a basal mandibular yellow spot and in the sternal sculpturing and shape of sternum 6 but differs in the larger parocular yellow areas and the slightly shorter antennae. Both sexes of arenicola are distinctive in the extremely short vertex. In facial view the lateral ocelli stand well above the line of the vertex whereas in nida the lateral ocelli is just at this line and in andrenoides and wellesleyana they are well below this line.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 9-10 mm; width, 2.5-3.0 mm; wing length, M = 3.17 ± 0.082 mm; FL/FW, M = 0.96 ± 0.004; POVL/FOVW, M = 3.19 ± 0.033.
INTEGUMENTAL COLOR. — As in dark specimens of andrenoides except as follows: flagellar segments 2-10 yellow to red below; tegulae testaceous; wing membranes colorless, veins yellow; metasomal terga broadly hyaline apically.
STRUCTURE. — Antennae as in andrenoides but flagellar segments 2-9 all at least slightly broader than long. Eyes, mandible and galea as in andrenoides. Labial palpus as in andrenoides but segmental ratio about as 1.0:0.7:0.5:0.7. Maxillary palpus as in andrenoides but ratio about as 1.0:0.8:0.6:0.6:0.6:0.5. Labral process as in andrenoides but often rounded apically rather than triangular. Clypeus, supraclypeal area, face and facial fovea as in andrenoides. Vertex extremely short, in facial view lateral ocelli extend well above vertex, with head tipped forward vertex equals less than half an ocellar diameter; surface dulled by fine tessellation and scattered minute punctures. Genal area as in andrenoides but surface usually moderately shiny, with abundant small punctures and delicate reticular shagreening.
Thorax with form and sculpturing as in andrenoides but mesoscutum shinier, coarsely reticular shagreening present but delicate. Wing venation and tibial spurs as in andrenoides.
Metasomal terga sculptured as in andrenoides but terga 2-4 with basal area punctures smaller and sparser (separated mostly by 3-5 puncture widths) and reticular shagreening denser. Pygidial plate as in andrenoides but apex usually somewhat truncate and internal triangle without apical raised ridge or ridge incomplete and not meeting apical margin of plate. Sterna as in andrenoides.
VESTITURE. — Generally white, occasionally thoracic dorsum with hairs extremely pale ochraceous to yellow. Pollen-collecting hairs as in andrenoides. Tergal vestiture as in wellesleyana. Sternal apical fimbriae present as in andrenoides.
MALE. MEASUREMENTS AND RATIOS. — N = 4; length, 7-9 mm; width, 1.5-9.0 mm; wing length, M = 2.86 ± 0.029 mm; FL/FW; M = 0.95 ± 0.003; FS1/FS2, M = 1.85 ± 0.073.
INTEGUMENTAL COLOR. — As in andrenoides except as follows: mandible with large basal yellow macula (lacking in stylopized specimens); parocular yellow macula large, posteriorly extending from tentorial pit to antennal fossa along outer subantennal suture and almost in a straight line laterally to eye margin (reduced and similar to andrenoides in stylopized specimens); flagellar segments 2-11 and apex of 1 yellow below; tegulae testaceous; wing membranes colorless, veins yellow to red; terga with apices broadly hyaline.
STRUCTURE. — Antenna extremely short, in repose not reaching scutellum; scape length equals first two and three-fourths flagellar segments; flagellar segment 1 equals distinctly less than segments 1 plus 2, segment 2 shorter than 3, segments 2-10 shorter than broad or quadrate, 11 slightly longer than broad. Eyes, mandible, and galea as in andrenoides. Labial palpus as in andrenoides but segmental ratio about as 1.0:0.6:0.6:0.6. Maxillary palpus as in andrenoides but ratio about as 0.9:1.0:0.9:0.9:0.9:0.7. Labrum and process, clypeus, supraclypeal area and face as in andrenoides. Vertex extremely short, in facial view lateral ocelli protruding above vertex, tipped forward vertex above lateral ocellus equals less than half an ocellar diameter. Genal area broad, one and one-half times eye in profile; surface moderately dulled by reticular shagreening and minute obscure punctures.
Pronotum with dorsoventral ridge pronounced, sculptured as in female but shiny posterior to ridge below oblique suture. Thoracic sculpturing as in female. Wing venation and tibial spurs as in andrenoides.
Metasomal terga as in female. Sterna with basal area punctures sparse, otherwise as in female. Sternum 6 with apical margin with broadly V-shaped emargination, lateral angles reflexed, toothlike, at right angles to surface or almost so (not directed anteriorly as in wellesleyana). Terminalia as in andrenoides and nida; gonocoxite with ventral inner angle at base of apical process short as in nida; penis valves with lateral lamellae as in nida. Sterna 7 and 8 as figured (Figs. 53-54).
VESTITURE. — Generally white; thoracic dorsum occasionally pale ochraceous. Hairs distributed as in female (but lacking pollen-collecting hairs) except as follows: tergum 2 often with apical pale band narrowly interrupted medially; sternal fimbriae weakly developed.
REMARKS. — Andrena arenicola shows an unusually high degree of parasitism by Strepsiptera. Out of 89 specimens (79 females and 10 males) known, 35 (29 females and 7 males) were stylopized. This amounts to approximately 40 percent parasitization. Because of the morphological changes induced in specimens by stylopization, none of the parasitized specimens were used in the measurements and ratios in the above descriptions.