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 is the largest Cnemidandrena. It was named colletina because of its superficial similarity to some large colletids. It is easily distinguished from all other Cnemidandrena by its large size, the punctured clypeus, and the black hairs laterally on the discs of metasomal terga 2 to 4, with the facial foveal vestiture white.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 11.5-14.5 mm; width, 3.5-5.0 mm; wing length, M = 3.79 ± 0.446 mm; FL/FW, M = 0.98 ± 0.235; FOVL/FOVW, M = 2.44 ± 0.136.
INTEGUMENTAL COLOR. — Black except as follows: antenna red-brown ventrally beyond second flagellar segment; apical half of mandible dark red; tegula shining light brown; wing membrane very slightly darkened apically; wing veins red-brown; tarsal segments except basitarsi yellow; tibial spurs pale yellow; metasomal terga widely hyaline apically; sterna more narrowly hyaline apically; basal half of pygidium red-black.
STRUCTURE. — Flagellar segments 1 to 3 equal in length to scape, flagellar segments 2 plus 3 slightly shorter than flagellar segment 1, flagellar segment 2 slightly shorter than flagellar segment 3. Eye almost 3.5 times as long as broad, with inner margin diverging slightly above except upper end incurved. Malar space short, 6 times as wide as long. Mandible in repose extends one-third its length beyond middle of labrum; notch of mandible tooth one-sixth length of mandible from mandible apex. Galea moderately tessellate, lateral surface two-thirds as broad as dorsal surface. Maxillary palpus reaching to apex of galea, segmental ratio 1.3:1.4:1.0:0.9:0.8:0.8. Labial palpal basal segment moderately compressed laterally, curved throughout, segmental ratio 1.9:0.8:0.5:0.7. Labral process prominent, flat, half as long as broad, with median emargination depth one-fourth length of labral process. Clypeus extending for half its length beyond lower level of eyes, slightly protuberant, with round, coarse, irregularly spaced punctures in lower half; punctures decreasing in size toward dorsal and lateral periphery; whole surface moderately shagreened with shagreening more dense dorsolaterally. Supraclypeal area moderately shagreened; supra-antennal area with longitudinal rugulae and indistinct, medium-sized interrugal punctures. Genal area 1.5 times as wide as eye, with fine, reticular shagreening, except narrow area near eye shiny. Vertex above lateral ocellus equals 1.5 ocellar diameters, with medium-sized punctures separated by 1 diameter, moderately tessellate. Facial fovea slightly longer than half length of eye, more than twice as long as broad, rounded above, narrowed below, not extending below level of antennal fossa, reaching above to a line above median ocellus.
Pronotum with humeral angle and ridge moderately developed, pronotal suture prominent, extending well beyond humeral ridge, with moderate tessellation, punctures obscure. Rest of mesosoma dorsally with coarse, dense tessellation. Propodeal enclosure with longitudinal rugulae medially in anterior half, dorsal and posterior surfaces of propodeum with prominent punctures, lateral, corbicular surfaces with medium-sized, widely spaced punctures in anterior third, with light, reticular shagreening, shiny. Mesepisternum with medium-sized punctures separated by 3 diameters, weakly tessellate. Metepisternum with light, nearly reticular shagreening, moderately shiny. Mesobasitarsus widest medially, nearly 3 times longer than wide, slightly narrower than metabasitarsus. Metabasitarsus widest in basal third, 3 times longer than wide, narrower than metatibia. Metatibia somewhat cuneate, widest basally, narrowing distally, more than 3 times as long as broad. Pterostigma linear, 4.5 times as long as broad, vein 1st m-cu meets second submarginal cell a little beyond middle.
Metasomal terga 1 to 4 with discs with medium-sized punctures separated by 2 diameters, closer on posterior margins of discs, moderately tessellate. Tergum 5 with nearly large punctures, punctures tilted toward posterior, anterior rim raised and thickened; weakly tessellate. Pygidial plate broad basally, V-shaped with apex blunted, lateral edges raised, anterior half with small, close punctures, posterior half impunctate. Sternum 1 with small, median, V-shaped, apical emargination, and medium-sized punctures separated by 2 diameters. Sterna 2 to 6 with small punctures separated by 1 diameter or slightly more. Sterna 1 to 6 lightly shagreened, surface nearly shiny.
VESTITURE. — Head hairs yellow, facial foveal hairs pale yellow. Thoracic hairs yellow above, white laterally and below; propodeal corbicula with long, plumose, widely spaced hairs in anterior third. Leg hairs yellow to white except as follows: brown to black hairs distally on metafemora and ventral distal edges of pro- and mesotibiae; brown dorsal and pale ventral hairs of scopa, and brown to black hairs of basitarsi.
Metasomal terga 1 to 4 with broad, white fasciae as wide as exposed areas; tergum 1 with long, dense, white, nearly vertical hairs throughout, except more prostrate posteriorly, forming a dense fascia. Terga 2 and 3 with scattered, white, appressed hairs on median thirds of discs; apical fasciae appressed; remainder of basal areas with scattered, erect, short, brown to black hairs, becoming more dense laterally. Tergum 4 similar but without white hairs on median third of basal area. Tergum 5 with dense, black, appressed hairs apically, erect, long, black hairs on basal area. Sternum 1 with median longitudinal tuft of hairs, white and erect anteriorly, brown to black and appressed posteriorly. Sterna 1 to 5 with apical fringes well developed, sterna 2 to 5 with subapical fimbriae well developed laterally, poorly developed in narrow median areas, hairs white to black; sterna 2 to 6 with remaining areas having nearly erect brown to black hairs.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 10.0-12.5 mm; width, 2.6-4.0 mm; wing length, M = 3.38 ± 0.178 mm; FL/FW, M = 0.98 ± 0.068; FS1/FS2, M = 1.38 ± 0.412.
INTEGUMENTAL COLOR. — Color as in female except as follows: antenna red-brown ventrally beyond 1st flagellar segment, mandible with a little more than apical third red, tarsi red-yellow, wing very lightly clouded apically.
STRUCTURE. — Scape shorter than flagellar segments 1 to 3; flagellar segment 1 longer than flagellar segments 2 or 3, flagellar segment 2 longer than flagellar segment 3. Eye 3 times as long as broad, inner margin diverging slightly above except for upper end slightly incurved. Malar space 8.5 times as wide as long; mandible in repose extends one-eighth of its length beyond middle of labrum, notch of mandible tooth equidistant between middle of labrum and mandible apex. Galea as in female. Maxillary palpus reaching slightly beyond apex of galea, segmental ratio 1.0:1.1:0.9:0.9:0.8:0.9. Labial palpus as in female except segmental ratio 1.5:0.7:0.6:0.9. Labral process strongly reflexed, half as long as broad, median emargination more than one-third as deep as labral process is long. Clypeus almost flat, extending for one-fourth its length below eyes; sculpture as in female. Gena, vertex and supraclypeal areas as in female except gena weakly angulate opposite midpoint of eye. Parocular areas with weak, longitudinal rugulae and medium-sized interrugal punctures.
Pronotum with humeral angle and ridge well developed, except humeral ridge broadly and shallowly depressed where crossed by pronotal suture. Sculpturing of mesosoma as in female except as follows: pronotum irregularly rugose dorsally, laterally with vertical rugulae except angle between ridge and posterior lobe polished; propodeal enclosure obliquely rugose laterally; lateral areas of propodeum weakly tessellate.
Metasomal terga sculptured as in female but punctures obscure, surfaces shinier. Sterna 2 to 5 with slight median emarginations; sterna 1 to 6 sculptured as in female. Sternum 7 (fig. 108) with basal apodemes narrowing slightly posteriorly, short, sparse hairs apically with row of short, fine hairs across basal apodeme anteriorly. Sternum 8 (fig. 109) with apex and neck region equal in length to basal region; neck region with abundant, long hairs, apex hyaline. Gonoforceps (figs. 105 to 107) in dorsal view obliquely flattened and expanded; penis valves strongly expanded laterally to slightly pointed processes, apices expanded, lobe-like.
VESTITURE. — Head and mesosoma color as in female; facial hair more dense than in female.
Metasomal terga 2 to 5 with prominent, white, appressed apical fasciae obscuring about half dorsal areas. Tergum 1 with whole surface obscured by long, erect, white hairs, forming a weak fascia apically; discs of remaining terga with erect, short hairs, white on tergum 2, becoming darker on each posterior tergum to brown-black on tergum 6; sternal vestiture as in female except apical fringes strongly developed on sterna 2 to 4.
VARIATION. — All males from California and Oregon, one male from Kaibab Forest, Coconino Co., Arizona, and two males from Nebraska, Lancaster Co., and Glenn, Sioux Co., are without black hairs on the posterior metasomal terga; the discal hairs are concolorous with the apical fasciae except for a very slight browning of some discal hairs are concolorous with the apical fasciae except for a very slight browning of some discal hairs on tergum 5. These males have the tarsi, except basitarsi, light yellow. One male from Kaibab Forest, Coconino Co., Arizona, has two submarginal cells in the right wing. Buckell (1949) records two females collected at Chilcotin, British Columbia, on April 16, 1921. This collection date is anomalous for A. colletina, and suggests that these two specimens are incorrectly identified. I have not seen the specimens, but doubting their identification, have excluded these data from the records for this species.