Reprinted by permission of the Regents of the University of California from:
Donovan, B. J. 1977. A revision of North American bees of the subgenus Cnemidandrena (Hymenoptera: Andrenidae). University of California Publications in Entomology: 1-107.
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This species is closely related to A. citrinihirta, but is a little larger, especially in the males, has the clypeus slightly less protuberant, the propodeal enclosure with a median, longitudinal depression, and metasomal tergum 2 laterally and anteriorly to the subapical fascia with a small patch of short, appressed hairs surrounded by short, erect hairs.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7.9-9.0 mm; width, 2.3-2.7 mm; wing length, M = 2.42 ± 0.114 mm; FL/FW, M = 1.03 ± 0.059; FOVL/FOVW, M = 3.01 ± 0.283.
INTEGUMENTAL COLOR. — Black except as follows: antenna with distal several flagellar segments lighter than remainder; mandible with apical half red; tibial spurs and distitarsi light yellow; tegula shining light brown, wing veins light brown-yellow; wing membrane moderately clouded apically; metasomal terga and sterna widely hyaline apically; pygidial plate dark red except for lateral raised areas light yellow in apical half.
STRUCTURE. — Scape slightly longer than flagellar segments 1 to 3; flagellar segment 1 slightly shorter than flagellar segments 2 plus 3. Eye 4 times as long as broad with inner margin diverging very slightly above except for upper end incurved. Malar space very short, 9 times wider than long. Mandible in repose extends for one-fourth its length beyond middle of labrum; notch of mandible tooth one-fourth of distance between middle of labrum and mandible apex from middle of labrum. Galea moderately tessellate, dorsal surface slightly wider than lateral surface. Maxillary palpus reaching slightly beyond apex of galea, segmental ratio 0.7:0.8:0.7:0.7:0.6:0.6. Labial palpus with basal segment flattened and curved laterally, apical segment attached subapically, subapical segment slightly so; segmental ratio 1.2:0.6:0.5:0.5. Labral process nearly flat, wide basally, twice as wide as long; apical emargination shallow, depth one-fourth length of labral process. Clypeus moderately protuberant, extending for more than one-third its length below lower level of eyes; dorsolateral fourth with large punctures separated by 1 diameter and area shagreened, remaining area with few, scattered punctures, smooth, shiny. Supraclypeal area with indistinct, broad, shallow punctures and light shagreening. Genal area about twice as wide as eye, with small punctures separated by 4 diameters, with indistinct shagreening posteriorly, surface shiny. Vertex above lateral ocellus equals 1 ocellar diameter, with weak tessellation. Supra-antennal area with longitudinal rugulae and obscure punctures, surface shiny. Facial fovea 3 times longer than wide, extending dorsally to a line below lateral ocellus, ventrally to a line below antennal fossa, rounded above, narrowed below.
Pronotum with humeral angle and ridge moderately developed, with reticular shagreening, pronotal suture weakly crossing humeral ridge. Scutum with small punctures separated by 3 to 4 diameters; anterior third with light shagreening, dorsal area nearly polished, moderately shiny. Scutellum with small, sparse, scattered punctures posteriorly, shiny. Metanotum shagreened, shiny. Propodeal enclosure with a broad, median, longitudinal depression, irregular transverse rugulae with scattered light tessellation; surface shiny; dorsoposterior areas shagreened, shiny, with small punctures separated by 2 to 4 diameters, lateral corbicular area with medium-sized punctures in anterodorsal fifth separated by 5 or more diameters, with reticular shagreening, shiny. Mesepisternum shagreened with small punctures above separated by 2 to 4 diameters; more widely scattered, less distinct below. Metepisternum shagreened. Mesobasitarsus widest medially, 2.5 times as long as wide, wider than metabasitarsus, as wide as metatibia. Metabasitarsus less than 4 times as long as broad, metatibia expanded apically, 3.5 times as long as wide. Wings with pterostigma 4 times as long as wide; vein 1st m-cu meets second submarginal cell slightly beyond middle.
Metasomal terga 1 to 4 with weak reticular shagreening, shiny, with small punctures laterally and medially separated by 3 diameters, punctures closer apically. Tergum 5 with reticular shagreening, shiny, and large punctures separated anteriorly by 1 diameter, crowded apically. Pygidial plate with apex rounded, narrow median longitudinal area raised, broad edges turned up. Sternum 1 with small apical median, V-shaped emargination with medium-sized punctures separated by 1 diameter, lightly shagreened. Sterna 2 to 6 shagreened except for narrow apical margins hyaline, punctures small, close.
VESTITURE. — Citrus yellow throughout except less colored ventrally and facial foveal hair yellow-white. Clypeus with hairs sparse or absent in lower median half. Scutum with abundant hairs, hairs short, close, medially. Scutellum with anterior half nearly naked. Propodeal corbicula with long, well spaced hairs in anterodorsal fifth. Trochanteral floccus imperfect.
Metasomal terga 1 to 4 with appressed apical fasciae obscuring more than half terga. Tergum 1 with remainder of disc with close, long, erect hairs. Disc of tergum 2 with long, erect hairs on anterior median third; shorter, erect hairs on lateral anterior fifths; small, lateral areas between apical fascia and anterior erect hairs with very short, appressed hairs. Terga 3 to 4 with very short, sparse, erect hairs on discs. Tergum 5 almost obscured by long, posteriorly directed hairs. Sternum 1 with long, erect hairs and well-developed apical fringe; sterna 2 to 5 with subapical fimbriae poorly developed in about median thirds, well developed laterally, apical fringes moderately developed, remaining areas with short, sparse, erect hairs except small, anterior median areas naked.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 5.8-8.8 mm; width, 1.4-2.5 mm; wing length, M = 2.92 ± 0.138; FL/FW, M = 0.97 ± 0.071; FS1/FS2, M = 1.27 ± 0.101.
INTEGUMENTAL COLOR. — Black except as follows: antenna red-brown ventrally in apical half, mandible with apical third red; legs brown, tibial spurs nearly white; basal half of tarsal claws light yellow, distal half red. Tegula shining brown, wing veins brown, wing membranes moderately clouded apically, metasomal terga and sterna with apical margins widely hyaline.
STRUCTURE. — Scape equal to pedicel plus flagellar segments 1 and 2; flagellar segment 1 more than 1.25 times as long as flagellar segment 2. Eye nearly 3.5 times as long as broad, inner margin diverging slightly dorsally except upper end incurved. Malar space, mandible and galea as in female except mandible with tooth notch one-third distance between middle of labrum and mandible apex from middle of labrum, and mandible without ventrobasal lamella. Maxillary palpus as in female except segmental ratio 0.8:0.8:0.7:0.5:0.6:0.6. Labial palpus as in female except segmental ratio 1.1:0.5:0.5 :0.5. Labral process strongly reflexed, twice as wide as long, median emargination depth half length of reflexed area. Clypeus slightly protuberant, extending below eyes for two-fifths of its length, with large punctures separated medially by 3 diameters, crowded on dorsolateral periphery, surface shiny. Supraclypeal area with large, crowded punctures. Gena produced to a blunt angle posteriorly; twice as wide as eye, with small punctures throughout separated by 5 diameters; posterior half shagreened, anterior half shiny. Supraclypeal and parocular areas with poorly developed rugulae and medium-sized punctures 2 to 3 diameters apart. Vertex 1.5 times diameter of lateral ocellus with weak tessellation and small punctures separated by 3 to 4 diameters.
Pronotum with humeral angle and ridge well developed, pronotal suture reaching humeral ridge; shagreened above and anterior to humeral angle and ridge; vertical rugulae below humeral angle and above pronotal suture shiny; remaining area between humeral ridge and pronotal lobe smooth, polished. Scutum, scutellum and metanotum as in female. Propodeal enclosure with a well defined, median longitudinal depression with transverse rugulae in about posterior half, anterior half with irregular rugulae, areas laterally to median depression with light tessellation, whole enclosure shiny. Propodeal dorsoposterior area weakly shagreened, shiny, with medium-sized punctures separated dorsally by 1 1/2 to 2 diameters, laterally by 3 to 4 diameters. Mesepisternum, metepisternum, and wings as in female.
Metasomal terga 1 to 5 with discs polished with small punctures separated on discs by 3 to 4 diameters, more crowded on apical margins of discs. Sternum 1 with shallow, median emargination; sterna 1 to 6 with small, shagreened areas basally, remainder polished, with small punctures separated by 6 to 8 diameters. Sternum 7 (fig. 83) with basal apodemes turned slightly inwards; emarginate apically, processes on each side of emargination with short, sparse hairs. Sternum 8 (fig. 84) with apex and neck region longer than basal region; apex rounded; neck with abundant, long hairs throughout. Gonoforceps (figs. 80 to 82) in dorsal view flattened, moderately expanded apically; in lateral view nearly straight. Penis valves strongly curved downward, lateral expansions smoothly curved.
VESTITURE. — Pubescence citrus yellow dorsally, nearly white ventrally. Terga 1 to 5 with apical fasciae of short hairs nearly appressed apically, becoming erect on disc, erect hairs on discs of terga 1 and 2 long, but tergum 2 with erect hairs shorter than erect hairs of tergum 1; erect hairs of terga 3 to 5 very short, shortest laterally. Sterna 1 to 6 with sparse, medium length hairs throughout; apical fringes strongly developed on sterna 2 to 5, hairs long.
VARIATION. — In both sexes the integumental color may vary from black to light red-brown throughout except for antennae. One female taken at Lone Pine Lake, Inyo Co., California, has the pronotum on the left side with a distinct horizontal ridge running posteriorly from the ventral end of the humeral ridge to the posterior margin of the pronotum; the right side is normal. In both sexes the sculpturing of the propodeal enclosure varies somewhat; about one-fourth of the females have little or no median depression; in males the median depression is always present, but the area anterior to this with irregular rugulae may vary in extent posteriorly.