Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1977. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VIII. Subgenera Thysandrena, Dasyandrena, Psammandrena, Rhacandrena, Euandrena, Oxyandrena. Transactions of the American Entomological Society 103: 1-144.
Please report text errors to: leah at discoverlife dot org.
This is a small species known only from Illinois and adjoining states and related rather closely to A. caerulea. Like phaceliae, the females of polemonii have a broadened, cuneate hind tibia but this is provided with highly plumose scopal hairs as in A. caerulea. The propodeal corbicula of polemonii has plumose internal hairs, unlike the simple hairs of phaceliae. Both sexes of polemonii have integument with faint greenish-blue reflections, a dulled clypeus and spear-shaped, dull galea. Robertson and other authors placed polemonii in the subgenus Ptilandrena because of the plumose scopal hairs. However, this species, unlike Andrena erigeniae, has a simple pronotum without humeral angle or ridge and certain other characters which suggest that it belongs with more closely related species such as phaceliae and caerulea.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 6-8 mm; width, 2.0-2.5 mm; wing length, M = 2.80 ± 0.111 mm; FL/FW, M = 1.10 ± 0.005; FOVL/FOVW, M = 3.55 ± 0.054.
INTEGUMENTAL COLOR. — Black with faint greenish-blue metallic reflections except as follows: mandible with apical third or less rufescent; flagellum below red to brown; tegula piceous or rufescent; wing membranes hyaline, clear to faintly infumate, veins reddish-brown to brown; terga 1-5 with narrow hyaline margins, apical areas basad of hyaline margins piceous to rufescent; sterna hyaline apically; tarsi dark; tibial spurs testaceous.
STRUCTURE. — Antennal scape length equals first four flagellar segments flagellar segment 1 equal in length to segments 2 plus 3 which are subequal in length, shorter than broad and shorter than segment 4; segments 4-9 quadrate to slightly longer than broad. Eyes each about four times as long as broad, inner margins converging slightly toward mandibles. Malar space, mandible and galea as in phaceliae. Maxillary palpus as in phaceliae but segmental ratio about as 1.0:0.8:0.8:0.8:0.7:0.8. Labial palpus as in phaceliae but ratio about as 1.0:0.6:0.6:0.8. Labral process entire, rounded apically, shiny; labrum below process convex, shiny, without cristae. Clypeus as in phaceliae but punctures smaller, separated mostly by one to two puncture widths, entirely dulled by tessellation. Supraclypeal area and genal area as in phaceliae. Vertex as in phaceliae but shorter, above lateral ocellus equal to about half an ocellar diameter. Facial fovea as in phaceliae but usually separated from lateral ocellus by one ocellar diameter or slightly more. Face above antennal fossae as in phaceliae but rugulae finer and closer together.
Thoracic form and sculpturing as in phaceliae but propodeal dorsal enclosure often without roughening basally, uniformly coarsely tessellate. Wing venation as in phaceliae but vein 1st m-cu usually meets second submarginal cell beyond middle of cell.
Metasomal terga 1-4 with discs with punctures absent or minute and obscured by regular tessellation, dull; apical areas often moderately shiny. Pygidial plate V-shaped, apex acute, not much rounded, internal raised triangle absent. Sterna 2-5 as in phaceliae.
VESTITURE. — Generally white to pale ochraceous except as follows: basitibial plate brown; inner surface tarsi dark brown, outer surfaces tarsi often brown; outer surfaces middle tibia largely brown. Vestiture generally sparse; clypeus with long sparse plumose hairs; thoracic dorsum with erect plumose hairs of moderate length; metasomal tergum 1 without apical fascia, terga 2-4 with apical fasciae but interrupted medially at least on tergum 2, discs with sparse short suberect pale hairs. Propodeal corbicula incomplete anteriorly, dorsally with long plumose hairs, internally with several long plumose hairs; trochanteral flocculus complete; tibial scopal. hairs highly plumose, short apicomedially and posteriorly; femur with dorsal surface hairs long, highly plumose.
MALE. MEASUREMENTS AND RATIOS. — N = 13; length, 6-7 mm; width, about 1.5 mm; wing length, M = 2.42 ± 0.086 mm; FL/FW, M = 1.11 ± 0.010; FS1/FS2, M = 1.57 ± 0.037.
INTEGUMENTAL COLOR. — As in female except as follows: flagellum red below, rarely dark; wing veins usually red; distitarsi usually dark rufescent.
STRUCTURE. — Antennae in repose reaching back to metanotum; scape length equals about first two and one-half flagellar segments or slightly less first flagellar segment one and one-third to one and three-fourths times as long as segment 2; segment 2 quadrate; remaining segments longer than broad. Eyes each about one and one-third times as long as broad, inner margins converging towards mandibles. Mandible, malar space, galea, maxillary and labial palpi as in female. Labral process large, shiny, entire or feebly emarginate apically; labrum below process shiny, convex, without cristae. Clypeus, supraclypeal area, genal area, vertex and face above antennal fossae as in female.
Thoracic form and sculpturing as in female but propodeal dorsal enclosure finely rugatulopunctate at least basally and propodeum outside of dorsal enclosure with more distinct punctures. Wing venation as in female.
Metasomal terga 1-5 sculptured as in female terga 1-4 but apical areas usually somewhat shinier. Sterna 2-5 as in phaceliae. Sternum 6 flat, emarginate as in phaceliae. Terminalia as in figures 119-123.
VESTITURE. — Generally white and relatively sparse; form and distribution as in female but without pollen-collecting hairs except as follows: terga 2-5 with weak pale apical fasciae interrupted medially on tergum 2, often on tergum 3 and rarely on tergum 4. Sterna 2-5 without subapical fimbriae inner surfaces tarsi pale yellow.
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 8 mm.; face somewhat longer than broad; clypeus slightly convex, projecting about one-half below suborbital line, dull and tessellate, punctures shallow, rather fine, well separated, becoming quite close at extreme sides; facial foveae rather narrow, occupying above about half of space between eyes and ocelli (as in distans, fig. 29), covered with whitish tomentum; space between margin of vertex and lateral ocelli very narrow, less than half diameter of ocelli, cheeks slightly broader than eyes, rounded posteriorly, dull and finely tessellate, punctures hardly visible; malar space very short; basal segment of flagellum subequal to 2nd and 3rd combined; process of labrum semicircular, about twice as broad as the median length, rather large; pubescence of head, thorax and legs greyish-white, becoming somewhat brownish on the more apical leg segments; thoracic integument dull, tessellate, faintly greenish, punctures of scutum and scutellum very minute and obscure, barely visible, well separated; pleura without visible punctures; dorsal area of propodeum oblique, triangle finely tessellate, propodeal corbicula whitish, rather poorly developed, short and thin, without a distinct anterior fringe; trochanteral floccus short and poorly developed; hind tibiae slender and elongate, apex not much broader than basitarsi, scopa whitish, quite dense, hairs rather short, finely plumose, front and mid basitarsi slightly narrower than their respective tibiae; 2nd submarginal cell slightly shorter than 3rd, receiving 1st recurrent near middle; abdominal terga dull, finely, but rather densely tessellate, faintly greenish, punctures exceedingly minute and obscure, rather sparse medially, becoming somewhat more close laterally, apical impressed areas narrow, quite shallow, not noticeably hyaline, discal pubescence extremely short, thin, sparse and obscure, apparently entirely pale, terga 2-4 with thin, whitish, apical fasciae, tergum 5 with a pale brownish, apical fimbria.
MALE. — Length 7 mm.; face slightly longer than broad; clypeus somewhat protuberant, projecting about one-half below suborbital line, somewhat shining medially, becoming dull around margin, punctures deep and distinct, rather coarse, well separated medially, becoming close toward sides and above; space between margin of vertex and lateral ocelli very narrow, less than half their diameter; cheeks slightly broader than eyes, rounded posteriorly (as in krigiana, fig. 30), dull, finely roughened, punctures hardly visible; malar space very short, but distinct; basal segment of flagellum subequal to 2nd and 3rd combined; process of labrum broad and rather short, length about half the basal width, slightly narrowed to the broadly truncate apex; mandibles rather short, with a distinct, inner, subapical tooth, overlapping about one-third; pubescence of head, thorax and legs entirely whitish, faintly tinged with ochraceous above; thoracic integument dull, densely tessellate, punctures of scutum very shallow and obscure, rather close anteriorly, becoming inevident posteriorly and on scutellum; pleura finely roughened above, without evident punctures; dorsal area of propodeum oblique, triangle very finely subrugose; all basitarsi slender and elongate, distinctly narrower than their respective tibiae; 2nd submarginal cell considerably shorter than 3rd, receiving 1st recurrent near middle, abdominal terga dull, rather densely but finely tessellate, punctures exceedingly minute and obscure, hardly visible, close over most of discs, apical impressed areas very shallow, rather short, not at all hyaline, discal pubescence extremely short, thin, sparse and entirely pale, fasciae not developed; apical portion of sternum 8 narrow, rather short, sides nearly parallel, apex narrowly truncate, covered beneath with short, thin pubescence; penis valves slender apically, somewhat dilated basally, sides excavated, gonocoxites quite slender, only very slightly dilated apically, gonocoxal lobes slightly produced.
DISTRIBUTION. — Illinois and Michigan; May.
FLOWER RECORDS. — Robertson (1929) records polemonii on Geranium maculatum, Polemonium reptans and Ranunculus septentrionalis.