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Text used courtesy of the Illinois Natural History Survey from:
Thorp, R. W., LaBerge, W. E., 2005. A revision of the bees of the genus Andrena of the Western Hemisphere. Part XV. Subgenus Hesperandrena. Illinois Natural History Survey Bulletin 37: 65-93.
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Andrena duboisi is a small species marked by the lack of pronotal humeral angles and ridges, a metallic green integument (especially head and thorax), and galeae which arc shiny and only extremely faintly shagreened. The male of duboisi can further be told from either A. escondida or A. pulverea by the yellow marking on the clypeus as described below and by sterna 2-5 having subapical fimbriae of extremely short, white plumose hairs.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 6.5-7.5 mm; WL, M = ¦ 2.3610.143 mm; FL/FW, M = 0.79 ± 0.007; FOVL/FOVW, M = 2.85 ± 0.050.
INTEGUMENTAL COLOR. — Head and thorax metallic green except clypeus, scutellum, and metanotum often with violaceous reflections. Metasomal terga black with faint metallic green reflections; tergal apical areas hyaline apically to red or reddish brown basally; sterna without metallic reflections, apical areas more broadly hyaline. Wing membranes hyaline, yellow, veins red to reddish brown. Mandible with apical fifth to fourth rufescent; antennal flagellum brown below; tibial spurs light yellow.
STRUCTURE. — Antenna! scape as long as first four and one-third flagellar segments; flagellar segment 1 slightly longer than following two segments together; segment 2 about as long as 3 and shorter than 4; segments 5-7 about as long as broad. Eyes each three and two-thirds times as long as broad, inner margins parallel. Mandibles short, apposite, with subapical tooth. Malar space linear. Galea shaped as in escondida, surface shiny, faintly if at all shagreened. Maxillary palpus as in escondida but segmental ratio about as ().8:1.0:0.8:0.7:().5:0.7. Labial palpus as in escondida but ratio about as 1.0:0.5:0.5:0.7. Labral process short, two to three times as broad as long, weakly emarginate apically with rounded lateral angles; labrum apical to process about as long as process, moderately dulled by shagreening. Clypeus shaped as in escondida', dulled by fine tessellation and minute punctures separated mostly by about two puncture diameters except more crowded along apical margin. Supraclypeal area dulled by coarse tessellation. Face above antenn.il fossae with small parallel rugulae to ocelli. Facial fovea as in escondida. Vertex above lateral ocellus equals about half an ocellar diameter. Genal area in profile one and one-half times width of eye or slightly less, surface dull, shagreened.
¦ Pronotum without humeral angle or lateral ridge or with only a trace of these structures; surface dull, shagreened. Mesoscutum as in escondida but punctures separated by one to three puncture widths except slightly more crowded peripherally. Scutellum and metanotum similar. Propodeum as in escondida but finely punctatorugose, basal area extremely narrow. Pleurae as in escondida.
Metasoma sculptured as in escondida, virtually impunctate. Pygidial plate as in escondida but usually more pointed, V-shaped with apex rounded. Sterna as in escondida.
VESTITURE. — White to pale ochraceous except as follows: facial fovea with tomentum pale brown in upper three-fourths or more, pale at lower end only; hind tarsi with inner sin lace pale yellow; terga 2-4 with distinct apical pale hair bands, that on tergum 2 interrupted medially by less than one-third width of tergum, terga 3 and 4 with bands complete. Pollen-collecting hairs as in escondida.
MALE: MEASUREMENTS AND RATIOS. — N = 9; length, 6.0-7.0 mm; width, 1.0-1.5 mm; WL, M = 1.68 ± 0.169 mm; FL/FW, M = 0.95 ± 0.006; FS 1/FS2, M = 2.10 ± 0.087.
INTEGUMENTAL COLOR. — As in female except as follows: clypeus with mediobasal pale yellow macula covering half of clypeus or more; head and thorax with metallic reflections blue or bluish green, mesoscutum occasionally with slight violaceous reflections; metasomal terga with metallic bluish green reflections on basal half of each tergum, hyaline apical margins broader than in female; distitarsi usually red.
STRUCTURE. — Antennae short, female-like; flagellar segment 1 as long as 2 plus 3, which are subequal and shorter than 4, segments 5-8 as long as broad or slightly longer; scape as in female. Eyes each slightly longer than three times as long as broad, diverging strongly towards vertex. Mandibles apposite, short, with subapical tooth. Galea as in female, shiny. Maxillary palpus as in female but segmental ratio about as 0.8:1.0:0.8:0.9:0.7:0.8. Labial palpus as in female but ratio about as 1.0:0.4:0.7:0.7. Labral process moderately long, about twice as broad as long, apical margin weakly emarginate, lateral teeth blunt, surface shiny; labrum apical to process about as long as process, dulled by shagreening. Clypeus sculptured as in female hut minute punctures more abundant. Supraclypeal area as in female. Face above antennal fossae with parallel rugulae almost from inner eye margin to inner eye margin, in median third or less of facial area rugulae often diverge towards ocelli. Vertex short as in female. Pronotum with distinct humeral angles and complete lateral ridges, surface shagreened. Mesoscutum and scutellum sculptured much as in female. Propodeum as in female bin sin lace outside of dorsal enclosure with punctures usually more distinct. Pleurae as in female.
Metasomal terga 1-6 sculptured as in female terga 1-5 but surfaces slightly shinier. Sterna much as in female. Sternum 7 has apical lobes broad and flattened, emargination much reduced. Sternum 8 with thick neck region, distinctly thicker than entire apical lobe.
TYPE MATERIAL. — The female holotype (USNM No. 59, 279) of Andrena duboisi was collected at Davis, California, May 2, 1937 by J.J. DuBois.
DISTRIBUTION. — Andrena duboisi occurs in California (Fig. 1) from Colusa County in the north to San Diego County in the south. It has been collected from March 19 through May 12 and a total of 63 females and 9 males have been taken from localities listed below (including localities cited in the literature).
CALIFORNIA. ALAMEDA CO.: Niles. COLUSA CO.: Bear Valley (9.7 mi. N of Highway 20 and 13.5 km. N of Wilbur Springs). CONTRA COSTA CO.: Russelmann Park (Mt. Diablo); Walnut Creek. FRESNO CO.: Mendota. LOS ANGELES CO.: Los Angeles. MONTEKEY CO.: Parkfield (6 mi. NE). SAN DIEGO CO.: San Diego. SAN FRANCISCO CO.: San Francisco. SANLUIS OBISPOCO.: Simmler(15 mi. SE). SANTA BARBARA CO.: Christi Beach, Santa Cruz Island. SOLANO CO.: Dixon (9 mi. S); Dozier (11 mi. S of Dixon). STANISLAUS CO.: Turlock. TULARE CO.: Strathmore, YOLOCO.: Davis.
FLORAL RECORDS. — Andrena duboisi was collected at Davis by J.J. DuBois presumably at Baeria sp., according to Timberlake (1951). It has been collected from flowers listed below.
Baeria sp., B. chrysostoma, Blennosperma nanum, Centromadia pungens, Lasthenia chrysostoma, Layia chrysanthemoides, and Limnanthes douglasii.
Andrena (Hesperandrena) duboisi Timberlake, 1951, Proc. United States Nat. Mus., 101:390-392.
Updated: 2021-05-13 11:37:56 gmt