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.
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This small species was placed in Micrandrena because the first transverse cubital vein often ends near the pterostigma, but usually at least three or four vein widths separate the pterostigma from the first transverse cubital vein and the pterostigma is not greatly broadened as in Micrandrena. It was subsequently placed in Thysandrena because of the close resemblance of females of that subgenus as then understood, in spite of the yellow clypeus of the male. The female of cercocarpi is like a Thysandrena but has short narrow facial foveae (much as in Euandrena), a simple labral process, and the labrum below the process is formed into two shallow shiny depressions by a median crista and two lateral folds or weak cristae.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 6-8 mm; width 1.5-2.5 mm; wing length, M = 2.80 ± 0.116 mm; FL/FW, M = 0.99 ± 0.005; FOVL/FOVW, M = 3.83 ± 0.075.
INTEGUMENTAL COLOR. — Black except as follows; mandible with apical one-third to one-half rufescent; flagellum reddish-brown; below; tegula translucent reddish-brown; wing membrane hyaline, veins and pterostigma brown to reddish-brown; terga 1-4 narrowly hyaline apically, remainder apical area often slightly rufescent especially medially; sterna 2-5 narrowly hyaline apically; legs dark reddish-brown to black; tibial spurs testaceous.
STRUCTURE. — Antennal scape length equal to first three and one-fourth to three and one-third flagellar segments; flagellar segment 1 about as long as segments 2 plus 3, segment 2 as long as 3 and shorter than 4, segments 2-7 shorter than broad, 8 and 9 quadrate. Eyes each about four times as long as broad, inner margins converging towards mandibles. Mandibles bidentate, short. Malar space narrow, linear. Galea of typical Thysandrena type, broad basally, narrowed to a point, apical half of lateral margin gently concave, surface, shiny, extremely finely shagreened or not at all. Maxillary palpus long, extending beyond galea by last two segments or more, segmental ratio about as 1.0:1.0:1.0:0.8:0.7:0.7. Labial palpus with first segment curved, terete, ratio about as 1.0:0.6:0.6:0.6. Labral process entire, triangular with blunted tip or narrowly trapezoidal, distinctly longer than half basal width; labrum below process formed into two shiny transverse depressions by median crista and two lateral weak cristae or folds. Clypeus low, convex, opaque, evenly tessellate with punctures obscure except near apical margin where punctures separated by half to one puncture width and irregular in size, depth and shape. Supraclypeal area tessellate, opaque. Genal area in profile about as broad as eye; surface dulled by fine reticular shagreening and minute obscure punctures. Vertex above lateral ocellus equal to one ocellar diameter or slightly less (about as 7:8) surface opaque, tessellate. Face above antennal fossae opaque, tessellate with minute longitudinal rugulae (coarsest in basal half and near foveae). Facial fovea short, narrow, extending below to a line at lower margins antennal fossae but not below; separated from lateral ocellus by one and one-half to two ocellar diameters (upper end of fovea extremely shallow and indistinct but if head is positioned so that light reflects from the short brown foveal hairs, the fovea can be seen to narrow at its upper end); fovea occupying about two-fifths to one-third of shortest distance between compound eye and inner margin antennal fossa.
Pronotum normal, surface dulled by fine even tessellation. Mesoscutum evenly, densely tessellate with minute barely discernible punctures separated mostly by two or more puncture widths. Scutellum similar. Metanotum densely tessellate. Propodeum with dorsal enclosure without rugulae or areolae, evenly tessellate; dorsal and posterior surfaces similarly tessellate lateral surface slightly more coarsely tessellate, slightly shiny below, with minute piliferous punctures. Mesepisternum evenly tessellate with minute sparse punctures barely visible. Wing venation as in subgeneric description first transverse cubital vein separated from pterostigma usually by three or four vein widths but occasionally by only one or two vein widths (20% of specimens). Posterior hind tibial spur straight or almost so.
Metasomal terga evenly tessellate except in narrow hyaline rims which are shiny; punctures minute, sparse, barely visible. Pygidial plate V-shaped with raised internal triangular area. Sterna 2-5 with narrow apical areas impunctate, basal thirds impunctate or sparsely punctate, remainder of discs with small round punctures separated mostly by one to two puncture widths; surfaces moderately dulled by fine reticular shagreening.
VESTITURE. — Generally white except as follows; facial foveal hairs brown vertex and along upper part of inner eye margins brown; terga 5 and 6 often brown medially; basitibial plate, end of hind femur, and tibia below plate brown. Thoracic hairs erect, mostly short, sparse; terga 2-4 with narrow. pale apical fasciae often interrupted medially on tergum 2 or terga 2 and 3; terga with discal hairs short, erect, sparse. Pollen-collecting hairs typical for the subgenus (and essentially identical to that of Thysandrena).
MALE. MEASUREMENTS AND RATIOS. — N = 14; length, 6-8 mm; width, 11.5-2.5 mm; wing length, M = 2.71 ± 0.133 mm; FL/FW, M = 1.03 ± fl.004; FS1/FS2, M = 0.87 ± 0.014.
INTEGUMENTAL COLOR. — Black with same exceptions as in female but clypeus yellow except narrow anterior dark rim, small dark spots below tentorial pits and narrow irregular posterior margin (never more than one-third of clypeus along midline and usually one-fifth or less).
STRUCTURE. — Antenna long, in repose reaching propodeum; scape length about equal to flagellar segments 1 plus 2 or slightly shorter; flagellar segment 1 slightly shorter than 2, segments 3-10 about one and one-half times as long as broad, segments 1 and 2 longer than broad. Eyes each about four times as long as broad, inner margins strongly converging towards mandibles. Mandible, malar space and galea as in female. Maxillary palpus as in female but segmental ratio about as 1.0:1.0:1.0:1.0:0.8:0.8. Labial palpus as in female ratio about as 1.0:0.5:0.5:0.6. Labral process bidentate, flat, shiny, more than half as long as basal width; labrum apical to process shiny, without cristae or these extremely weak, punctate at base near process. Clypeus, supraclypeal area, genal area, vertex and face above antennal fossae as in female but face with longitudinal rugulae slightly coarser.
Thoracic sculpturing as in female. Wing venation as in female but first transverse cubital vein often (about one-third of specimens) ending within one or two vein widths of pterostigma.
Metasomal terga as in female but punctures more evident especially on last three or four terga. Vestigial narrow pygidial plate present. Sterna 2-5 with disc punctures separated by two to four or more puncture widths, surfaces reticularly shagreened. Sternum 6 flat, apical margin gently emarginate. Terminalia as in A. congrua.
VESTITURE. — Generally as in female without pollen-collecting hairs except as follows: thoracic dorsum with hairs long, erect, sparse; terga 2-4 with pale apical fasciae often interrupted medially; tergum 1 with sparse long hairs; sterna 2-5 with complete but weak subapical fimbriae of short white hairs; sternum 6 without apical tuft or band.
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