Text used courtesy of the Illinois Natural History Survey from:
LaBerge, W. E., Thorp, R. W., 2005. A revision of the bees of the genus Andrena of the Western Hemisphere. Part XIV. Subgenus Onagrandrena. Illinois Natural History Survey Bulletin 37: 1-63.
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Andrena blaisdelli is a small species from southern California closely related and similar to Andrena furva. The female of blaisdelli can be told from that of furva by the longer hairs of the mesosomal dorsum, the broader apical part of the labral process, the shorter vertex, the more finely sculptured mesepisterna and propodeum, and the slightly sparser scopal hairs. The male of blaisdelli is one of the species of Onagrandrena with the vestiture entirely white. It differs from the male of furva by the shorter vertex, the more finely sculptured mesepisterna, and the longer first flagellar segment. Both furva and blaisdelli have small shiny galeae and can be told by these from all other species of Onagrandrena.
FEMALE: MEASUREMENTS AND RATIOS. — N = 20; length 10-12 mm; width, 3.0-3.5 mm: WL, M = 3.35 ± 0.135 mm; FL/FW, M = 0.98 ± 0.003; FOVL/FOVW, M = 3.34 ± 0.039.
DIAGNOSIS. Vestiture black; wing membranes hyaline, only slightly infumate, veins dark brown; metasomal terga black without metallic reflections. Galeae short, narrow, shiny, not or only finely shagreened; labral process longer than half length of labrum, sides strongly concave, apical part thick, as broad as base of first flagellar segment or broader, usually distinctly emarginate apically. Clypeus with dense small punctures, without medial impunctate line (or with incomplete line), shiny; vertex above lateral ocellus usually equals slightly less than one ocellar diameter, never more. Pronotum without humeral angle or vertical ridge laterally. Mesoscutum and scutellum densely punctate, punctures small, round, surface dulled by fine tessellation; mesepisternum moderately punctatorugose, dulled by shagreening. Propodeum with distinct dorsal surface, dorsal enclosure irregularly rugulose; surface outside of enclosure moderately coarsely punctatorugose, dull. Tergum I with basal area shiny, punctate; terga 2-4 with basal areas with punctures separated mostly by half to one puncture width; apical areas slightly upturned, with basal one-third to one-half with small punctures as dense as in basal area, apical third or half impunctate and often slightly upturned; surfaces shiny. Thoracic dorsum with hairs much longer than width of scape; propodeum without distinct corbicula, internal hairs long, plumose; scopal hairs long, sparse, simple, not fully hiding surface.
MALE: MEASUREMENTS AND RATIOS. — N = 16; length, S-11 mm; width, 2-3 mm; WL, M = 3.05 ± 0.200 mm; FL/FW, M = 1.02 ± 0.004; FS1/FS2. M = 1.46 ± 0.029.
DIAGNOSIS. Vestiture white except some short brown hairs occasionally present on vertex. Wing membranes hyaline, not infumate or only slightly so, veins dark reddish brown. Terga black to dark reddish brown, apical areas often somewhat hyaline. Galeae as in female; vertex above lateral ocellus as in female; flagellar segment I with minimum length distinctly longer than segment 2 (about as 1.2 to 1.5: 1.0), usually longer than segment 3. Pronotum as in female; mesoscutum and scutellum sculptured as in female; propodeum as in female but dorsal enclosure with irregular rugulae somewhat finer; mesepisterna sculptured as in female. Metasomal terga 2-5 sculptured similar to female terga 2-4 but basal area punctures somewhat sparser, usually separated by half to two puncture widths and apical areas with impunctate rims shorter (usually one-third or less of length of apical area). Metasomal tergum 2 with basal area hairs very short, erect, mediobasally much less than half as long as those of tergum 1; hind tibiae with outer surface hairs moderately long, along anterior margin a few almost as long as dorsal femoral hairs. Sternum 7 somewhat flattened apically with a small apicomedian emargination similar to omninigra, but less hairy. Sternum S strongly capitate, without apical emargination (Figs. 39 and 40).
TYPE MATERIAL. — The holotype female (CAS No. 1,708) of Andrena (O.) blaisdelli was collected in San Diego, San Diego Co., California, May 30, 1890, by F. E. Blaisdell.
DISTRIBUTION. Andrena blaisdelli is known only from southern California and Baja California del Norte (Linsley, MacSwain, Raven, and Thorp, 1973, p. 28) (Fig. 2). It has been collected from March 10 through August 2, but chiefly from late March through early May. A total of 143 females and 21 males were examined from the localities listed below.
CALIFORNIA. KERN CO.: Woody. LOS ANGELES CO.: Altadena; Claremont; La Crescenta; La Mirada; Pasadena; Pico Canyon (W of Hwy. 5 and W of Newhall); Tujunga. ORANGE CO.: Costa Mesa. RIVERSIDE CO.: Anza (5 mi. E); Gavilan; Moreno (3 mi. NE); Riverside: Sage (5 mi. S); Temecula (7 mi. E). SAN BERNARDINO CO.: Cajon Pass; Mohave Desert (near Deep Creek). SAN DIEGO CO.: Descanso-Alpine; Lakeside (2 mi. NR); Plum Canyon; San Diego; Sentenac Canyon. SAN LUIS OBISPO CO.: Santa Margarita (5 mi. NE); Simmler (10 mi W). W). SANTA BARBARA CO.: New Cuyama (28 mi. NW). TULARE CO.: Fairview (1 mi. S). VENTURA CO.: German (5 mi. S in Hungry Valley). MEXICO. BAJA CALIFORNIA DEL NORTE: La Zapopita, Valle de Trinidad.
FLORAL RECORDS. Although doubtlessly an oligolege of Camissonia, this species has been collected from that plant only a few times. However, several females without floral data have at least a few Camissonia pollen grains in their scopae. Andrena blaisdelli has ken collected from flowers of the plants listed below.
Camissonia bistorta, C. californica, C. campestris (as dentata), Cryptantha sp., C. intermedia, Eriophyllum sp., E. confertiflorum, Salix lasiolepis, Yucca whipplei.