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 can be recognized in the female sex by its virtual lack of a propodeal corbiculum. The hairs along the dorsal margin of the lateral surface of the propodeum are short and not differentiated from other hairs of the propodeum and the internal corbicular hairs are relatively short and simple. Both sexes of geranii are distinctive in that the front wings have vein 1st m-cu meeting the second submarginal cell before the middle of the cell. The integument in both sexes frequently has faint metallic blue reflections, the clypeus and terga are usually shiny and only lightly shagreened if at all, and the galea is relatively long and shiny.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-11 mm width, 2-3 mm; wing length, M = 3.31 ± 0.159 mm; FL/FW, M = 1.07 ± 0.008; FOVL/FOVW, M = 4.06 ± 0.064.
INTEGUMENTAL COLOR. — Black except as follows: frequently with faint metallic-blue reflections especially on clypeus and metasomal terga; mandible with apical third rufescent; flagellum below dark brown to dark reddish-brown; tegula translucent; wing membranes moderately infumate, veins dark brown to black; metasomal terga with apical areas translucent; sterna 2-5 with narrow apical areas hyaline, colorless or yellow.
STRUCTURE. — Antennal scape length equals first four flagellar segments flagellar segment 1 slightly longer than segments 2 plus 3, segment 2 equal in length to 3, each slightly shorter than broad; segments 4-9 quadrate to slightly longer than broad. Eyes each about three and three-fourths times as long as broad, inner margins parallel to converging slightly towards mandibles. Malar space short, linear. Mandible short, in repose surpassing midline of labrum by one-fourth or less of mandible length. Galea extremely narrow, acute, longer than median length of clypeus, outer margin straight; surface shiny, unshagreened. Maxillary palpus exceeds galea b last segment or slightly more when both extended; segmental ratio about 1.0:0.9:0.8:0.8:0.8:0.8. Labial palpus as in Thysandrena but segment ratio about as 1.0:0.8:0.6:0.8. Labral process entire or extremely slightly emarginate apically, shiny, flat; labrum below process with single weak median crista usually present. Clypeus strongly protuberant, with distinct round punctures separated by one to two puncture widths; surface shiny, unshagreened except basally, occasionally reticularly shagreened throughout. Supraclypeal area dull, finely rugatulopunctate. Genal area in profile broader than eye (about as 5:4), smoothly rounded posteriorly surface dulled by reticular shagreening and minute punctures. Vertex above lateral ocellus equal to one ocellar diameter or slightly less; surface dull, finely tessellate, obscurely punctate. Face above antennal fossae moderately dull, with weak longitudinal rugulae and abundant small punctures. Facial fovea long, narrow, usually extending to slightly below a line at lower margins of antennal fossae, separated from lateral ocellus by one ocellar diameter or slightly less; occasionally shorter.
Pronotum dulled by fine reticular shagreening, punctures sparse, obscure. Mesoscutum with small round punctures separated mostly by one to two puncture widths or more, surface dulled by reticular shagreening. Scutellum similar but often shiny medially. Metanotum dulled by small crowded punctures and dense tessellation. Propodeum with dorsal enclosure roughened by weak, irregular areola which become short rugulae at extreme base dorsal area outside of enclosure and posterior surface dull, tessellate with distinct punctures roughening surfaces; lateral surfaces coarsely tessellate with scattered, obscure, piliferous punctures. Mesepisternum densely tessellate with round punctures separated mostly by half to one puncture width or more. Pterostigma broad, long; vein 1st m-cu meets second submarginal cell before middle of cell (often in basal third of cell); vannal lobe hind wing broad, long.
Metasomal tergum 1 usually shiny, unshagreened or delicately shagreened, with minute sparse punctures separated by four or more puncture widths. Terga 2-4 similar but shagreening often more evident especially basally and minute punctures separated mostly by two to three puncture widths. Pygidial plate V-shaped with rounded apex, internal raised triangle not present. Sterna 2-5 with narrow apical areas impunctate, basal third of disc sparsely punctate, remainder of disc with distinct punctures separated by one to two puncture widths; surfaces shagreened, moderately dull.
VESTITURE. — Ochraceous to white except as follows: dorsum of thorax often slightly yellowish; terga 5 and 6 with brown hairs at least medially basitibial plate dark brown; tarsi dark brown to ochraceous; fore and middle tibiae usually brown. Vestiture generally sparse; clypeus with sparse, moderately long, mostly simple hairs; propodeal corbicula incomplete anteriorly, with short dorsal fringe, internal simple hairs short; trochanteral flocculus weak; tibial scopal hairs simple, long; hind femora with dorsal hairs highly plumose. Metasomal terga 2-4 with weak apical fasciae of long white hairs usually interrupted medially at least on terga 2 and 3.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 6-10 mm; width, 1.5-2.5 mm; wing length, M = 2.79 ± 0.257 mm; FL/FW, M = 1.10 ± 0.009; FS1/FS2, M = 1.38 ± 0.028.
INTEGUMENTAL COLOR. — Black with same exceptions as in female but flagellum occasionally yellow below and tergal apical areas often hyaline: colorless at least apically.
STRUCTURE. — Antenna in repose reaching posterior margin of scutellum; scape length equal to first two and one-third flagellar segments; flagellar segment 1 longer than segment 2 and often longer than 3; segment 2 shorter than 3, about as long as broad or slightly longer; segments 3-11 longer than broad. Eyes each about three and one-fourth times as long as broad, inner margins converging towards mandibles. Mandible, malar space, and galea as in female. Maxillary palpus as in female but segmental ratio about 1.0:0.9:0.9:0.7:0.6:0.7. Labial palpus as in female but ratio about as 1.0:0.7:0.6:0.7. Labral process weakly emarginate apically slightly flexed at apex, shiny; labrum below process shiny, without cristae. Clypeus as in female but punctures often more abundant, separated by half to one or two puncture widths; surface usually shiny. Supraclypeal area, genal area and vertex as in female. Face above antennal fossae as in female but fine longitudinal rugulae present almost to eye margins.
Thoracic form and sculpturing as in female but propodeum outside of dorsal enclosure with punctures coarser, distinctly roughening surfaces. Wing venation as in female.
Metasomal terga sculptured as in female but tergum 1 with fine punctures slightly more abundant; apical areas terga impunctate. Sterna 2-5 with apical areas impunctate, discs with sparse punctures; surfaces moderately shiny, reticularly shagreened. Sternum 6 flat, emarginate apically. Terminalia as in Figures 99-103.
VESTITURE. — Generally as in female but without pollen-collecting hairs and legs and terga 6 and 7 usually with pale hairs.
REMARKS. — Andrena geranii exhibits a rather unusual degree of size polymorphism, especially in the male sex. This is not related to geography in any way. The lack of metallic-blue reflections of the integument seems to be the main difference between typical geranii and campanulae. However, both forms appear throughout the range of geranii and Robertson (from unpublished notes) was aware of the existence of both forms of geranii.
Reprinted with permission from: Mitchell, T.B. 1960. Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 141.
FEMALE. — Length 9 mm.; clypeus quite strongly protuberant and convex, projecting nearly one-half below suborbital line, shining, punctures deep and distinct but rather fine and quite sparse, without a distinct, median, impunctate line; facial foveae rather narrow, occupying above about two-thirds of area between eyes and lateral ocelli, (as in novaeangliae, fig. 43) covered with whitish tomentum; space between margin of vertex and lateral ocelli subequal to their diameter; cheeks very slightly broader than eyes, rounded posteriorly, rather dull, punctures very minute and obscure; malar space extremely short; basal segment of flagellum subequal to 2nd and 3rd combined; process of labrum subtriangular, apex rather narrowly truncate; pubescence of head, thorax and legs silvery-white, becoming fuscous on the more apical leg joints; thoracic integument rather dull, punctures of scutum fine and shallow, but distinct, well separated but not sparse in center posteriorly, scutellum somewhat more shining, punctures deep and distinct, rather sparse and irregular; pleura dull and densely tessellate, punctures barely evident; enclosure of propodeum dull, obscurely substriate toward basal margin; propodeal corbicula very thin and poorly developed, without an anterior fringe; trochanteral floccus short and poorly developed, white; hind tibiae rather slender and elongate, all basitarsi only slightly narrower than their respective tibiae; 2nd submarginal cell considerably shorter than 3rd, receiving 1st recurrent slightly basad of middle; abdominal terga smooth and shining, very minutely and quite sparsely punctate, punctures invading apical depressed areas which are shallow and obscure, occupying medially about one-third length of discs and becoming faintly testaceous along rims, discal pubescence thin but quite long and erect, entirely pale, forming rather narrow, loose apical fasciae on terga 2-4, tergum 5 with a quite dense, brownish, apical fimbria.
MALE. — Length 8 mm.; clypeus rather strongly convex, projecting about one-third below suborbital line, shining, punctures deep and distinct, rather sparse medially, becoming rather close laterally; space between margin of vertex and lateral ocelli subequal to their diameter; cheeks slightly broader than eyes, rounded posteriorly, dull, very obscurely and minutely punctate; malar space extremely short; basal segment of flagellum slightly longer than 2nd segment, but considerably shorter than 2nd and 3rd combined; process of labrum about twice as broad as long, obscurely subtriangular, apex rather broadly truncate; mandibles rather short, with a distinct, inner, subapical tooth, very slightly overlapping; pubescence of head, thorax and legs silvery-white; thoracic integument dull, finely tessellate, punctures of scutum shallow and rather indistinct, well separated, becoming somewhat sparse in center posteriorly, those on scutellum somewhat deeper and more distinct, irregularly scattered, surface more shining; pleura densely tessellate, punctures very obscure; enclosure of propodeum dull and densely tessellate; basitarsi slender, considerably narrower than their respective tibiae; 2nd submarginal cell somewhat shorter than 3rd, receiving 1st recurrent near base; abdominal terga somewhat shining, minutely and rather sparsely punctate, apical depressed areas narrow and obscure, becoming yellowish-hyaline along rims, pubescence entirely pale, short and erect, forming loose, narrow, white, apical fasciae on terga 2-4; apical portion of sternum 8 abruptly narrowed at the base, parallel-sided, but rather broadly dilated apically, the apex truncate and slightly incurved, very thinly pubescent; penis valves narrow, not at all broadened basally, gonocoxites slender but very slightly dilated apically, gonocoxal lobes rather strongly produced, but narrowly rounded.
DISTRIBUTION. — Colorado and Minnesota, east to Virginia and the New England states; April to July.
FLOWER RECORDS. — Hydrophyllum. Robertson (1929) records this species on Arabis, Blephilia, Geranium, Osmorrhiza and Polymonium.