Reprinted with permission of the University of Nebraska State Museum from:|
LaBerge, W. E. 1967. A revision of the bees of the genus Andrena of the Western Hemisphere. Part I. Callandrena (Hymenoptera: Andrenidae). Bulletin of the University of Nebraska State Museum 7: 1-316.
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This small species is the nearest relative of A. accepta. The female of trimaculata differs from that of accepta by the three large facial maculae (two parocular and one clypeal). The male can be distinguished from that of accepta by the shorter clypeus. Both sexes have the supraclypeal area shinier and more punctate than in accepta and have the genal area less broad.
FEMALE. MEASUREMENTS AND RATIOS. — N = 1; length about 10.0 mm; width about 3.0 mm; wing length, 3.38 mm; FL/FW = 1.14; FOVL/FOVW = 2.38.
INTEGUMENTAL COLOR. — As in accepta except as follows: clypeus with mediobasal yellow macula equal to about one-third of clypeal area and almost equal to parocular maculae in area; flagellar segments 4-10 reddish-orange below; tegulae brown; wing membranes moderately infumate apically, veins dark brown; tergal apices broadly hyaline, reddish; sterna piceous.
STRUCTURE. — Antennae and eyes as in accepta but eyes converging slightly towards mandibles. Malar space, mandible and galea as in accepta but mandible lacks ventrobasal lamella. Maxillary palpus shorter than galea, in ratio of about 1.6:1.8:1.2:1.0:0.8:1.4. Labial palpus with segment 1 compressed and strongly curved and longer than succeeding segments together, in ratio of about 2.7:1.0:0.6:0.9. Labral process as in accepta. Clypeus Hat with large round punctures of irregular size, largest twice diameter of smallest or more, separated by one-half to one puncture width except sparser medially; yellow mediobasal area of clypeus much flatter, surrounded apically by irregular, low ridge, surface shiny, shagreening extremely sparse. Supraclypeal area with small round crowded punctures, surface shiny. Genal area only slightly broader than eye in profile, with round crowded punctures near eye, separated by half or less puncture width, sparser further from eye, surface shiny. Vertex equals about two ocellar diameters above lateral ocellus, punctures deep, crowded at apex, sparse laterad of ocelli, surface dulled by sparse reticular shagreening. Face as in accepta but punctures more abundant. Facial fovea more than two times as long as broad.
Pronotum as in accepta but surfaces moderately shiny. Mesoscutum and scutellum as in accepta but punctures somewhat more crowded and surfaces shiny, unshagreened. Propodeum with enclosure with extremely fine, irregular rugulae basally, granular in apical half; lateral and posterior areas with punctures separated by half a puncture width or less, moderately shiny; corbicular areas as in accepta. Mesepisternum and metepisternum as in accepta but the latter largely impunctate and shiny. Hind tibia and tibial spurs as in accepta. Wing venation as in accepta but 1st m-cu meets second submarginal cell at about two-thirds distance from base of cell.
Metasomal terga as in accepta but punctures seem deeper and more crowded, generally separated by less than half a puncture width, surfaces shiny, unshagreened or only delicately so. Pygidial plate and sterna as in accepta.
VESTITURE. — Hair generally light ochraceous or cinereous except inner surfaces tarsi and outer surfaces hind basitarsi brownish-red. Distribution and type of hairs as in accepta except as follows: mesoscutal and scutellar hairs much shorter, highly plumose, giving dorsum of thorax a velvety appearance; terga with basal area hairs mostly extremely short and fine, basal areas except in profile appear almost naked.
MALE. MEASUREMENTS AND RATIOS. — N = 1; length about 10.0 mm; width about 2.5 mm; wing length, 3.4 mm; FL/FW = 0.96; FS1/FS2 = 2.50.
INTEGUMENTAL COLOR. — Color as in female except as follows: clypeus yellow except broad apical margin and two small maculae at tentorial pits brown to black; flagellar segments 2-11 dark red below tegulae reddish-brown; basitarsi and tibiae somewhat rufescent.
SIRUCTURE: Antennae as in accepta. Eye more than three times as long as broad, converging strongly toward mandibles. Malar space, mandible and galea as in female. Maxillary palpal ratio about 1.0:1.0:0.8:0.8:0.6:1.1. Labial palpus as in female, palpal ratio about 2.6:1.0:0.7:1.1. Labral process narrow apically, strongly reflexed, bidentate and ribbed. Clypeus flat, barely protruding below lower margins of eyes, apical margin turned out and thickened, with large round punctures separated by one-half to one puncture width except sparser medially, surface shiny, unshagreened. Supraclypeal area as in female. Genal area considerably broader than eye in profile (but less than one and one-half times eye), sculptured as in female. Vertex above lateral ocellus equals almost three ocellar diameters, sculpturing as in female but punctures more abundant laterally and surface shiny, unshagreened. Face as in female. Thoracic sculpturing as in female except as follows: propodeal enclosure with weak transverse rugulae throughout, dorsolateral, posterior and corbicular areas with punctures sparser and surfaces shinier; mesepisternum with surface shiny. Terga as in female. Sterna 2-6 as in accepta. Sterna 7 and 8 and genital capsules (Figs. 50-54) similar to that of accepta.
VESTITURE. — Color white to cinereous (slightly darker above) except inner surfaces tarsi yellow. Distribution and type of hairs as in accepta except terga with basal area hairs somewhat shorter and tergum 1 with apical area with a more distinct appressed pubescent band.
TYPE MATERIAL. — The holotype female was collected by G D. Butler at Canelo, Arizona, October 19, 1957. The allotype male was collected by G. D. Butler at Canelo Arizona, October 11, 1955. Both specimens are the property of the University of Arizona at Tucson but are on permanent loan to the Illinois Natural History Survey.
REMARKS. — A male collected by P. H. Arnaud, Jr., T. S. Ross and D. C. Rentz, 9 miles south of San Juan del Rio, Durango, Mexico, August 21, 1960, is placed with this species although it differs from the allotype male. The Durango male is slightly smaller than the allotype, has the pale facial maculae cream-colored rather than yellow, and the hind basitarsus and apex of the hind tibiae orange.