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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The female of Andrena pulverea is like that of escondida in lacking pronotal humeral angles and lateral ridges but can be recognized by the large labral process which is entire, about one and one-half times as broad as it is long, usually triangular with a low apical boss. The male of pulverea is like that of escondida in having a black clypeus but can be separated from that species by the presence of weak humeral angles, flagellar segment 3 being slightly longer than segment 2, rather than the inverse, and the lack of sternal subapical fimbriae.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 9-10 mm; width, 2.0-2.5 mm; WL, M = 2.68 ± 0.125 mm; FL/FW, M = 0.94 ± 0.005; FOVL/FOVW, M = 3.04 ± 0.047.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical fifth to almost half rufescent; flagellum below dark brown; wing membranes hyaline, slightly infumate, yellowed, veins reddish brown to dark brown; metasomal terga with apical areas often slightly reddened, narrowly hyaline apically; tibial spurs yellow.
STRUCTURE. — Antennal scape as long as first four flagellar segments or slightly shorter; flagellar segment 1 slightly longer than segments 2 plus 3, segments 2 and 3 subequal, shorter than 4, segments 5-7 about as long as broad. Eyes each almost four and a half times as long as broad, inner margins parallel. Mandibles short, apposite, with subapical tooth. Malar space short, linear. Galea as in escondida. Maxillary palpus as in escondida but segmental ratio about as 0.7:1.0:0.8:0.7:0.6:0.6. Labial palpus normal, segmental ratio about as 1.0:0.5:0.5:0.6. Labral process large, entire, usually triangular with blunted apex and small apical boss, occasionally rounded with apical boss; labrum apical to process as in escondida. Clypeus as in escondida hut punctures sparse and indistinct almost to apical margin. Supraclypeal area and face above antennal fossae as in escondida. Facial fovea as in escondida but slightly longer. Vertex above lateral ocellus usually equals less than half an ocellar diameter. Genal area in profile as in escondida.
Pronotum as in escondida. Mesoscutum sculptured as in escondida but punctures I sparse, obscure in anterior third and near parapsidal lines. Scutellum tessellate, punctures minute, widely separated. Propodeum as in escondida but dorsal enclosure not roughened basally. Pleurae as in escondida.
Metasomal terga sculptured as in escondida, punctures minute, essentially impunctate. Pygidial plate and sternal sculpturing as in escondida.
VESTITURE. — White to pale ochraceous except as follows: facial fovea with tomentum brown to golden brown, facial hairs otherwise often dark ochraceous; inner surfaces tarsi light yellow; scopal hairs often golden-brown along margin. Terga 2-4 with apical pale fasciae extremely weak, thin, that of tergum 2 interrupted medially by more than one-third width of tergum. Pollen-collecting hairs as in escondida but trochanteral flocculus usually with more abundant hairs.
MALE: MEASUREMENTS AND RATIOS. — N = 20; length, 7-9 mm; width, 1.5-2.5 mm; WL, M = 2.41 ± (). 123 mm; PL/FW, M = 0.96 ± 0.006; FS1/FS2, M = 1.85 ± 0.045.
INTEGUMENTAL COLOR. — As in female except as follows: wing membranes less infumate, veins often dark red; terga with apical areas translucent, ferruginous; sterna 2-5 narrowly hyaline apically.
STRUCTURE. — Antennae short, female-like; flagellar segment 1 usually slightly shorter than in escondida, twice as long as segment 2, segment 3 distinctly longer than 2, broader than long, segments 4-7 usually slightly longer than broad; scape length as in female. Mandibles apposite, short, with subapical tooth. Maxillary palpus and segmental ratio as in female. Labial palpus as in female but ratio about as 1.0:0.5:0.5:0.5. Labral process about twice as long as broad, at least as long as labrum apical to process, bidentate, recurved, shiny. Clypeus sculptured as in female but punctures more abundant, separated mostly by one to three diameters. Face above antennal fossae with minute rugulae often strongly diverging towards ocelli. Vertex as in female. Genal area at least one and one-half times as broad as eye in profile, sculptured as in escondida. Pronotum with distinct humeral angles and weak lateral ridges. Thoracic sculpturing as in female. Metasomal terga sculptured as in female; sterna 2-5 tessellate, dull, with punctures mostly obscure. Terminalia (Figs. 22 and 23). Sternum 7 much as escondida but apical lobes slightly more separated; sternum 8 usually longer and narrower than in escondida.
VESTITURE. — White to pale ochraceous but inner surfaces of tarsi pale yellow and occasionally brown along inner margins of eyes and on vertex near ocelli. Metasomal terga 25 with apical pale fasciae extremely weak, that of tergum 2 interrupted medially by half width of tergum or more. Sterna 2-5 without dense subapical fimbriae of pale hairs.
TYPE MATERIAL. — The holotype female of pulverea (PANS No. 4,043) was collected in California. The holotype female of limnanthis (USNM No 59,277) was collected at San Geronimo, Marin Co., California, April 23, 1913 by J.C. Bridwell.
DISTRIBUTION. — Andrena pulverea is known (Fig. 1) only from central California from Colusa County in the north to Merced County in the south. It has been collected from March 1 to June 2, but chiefly in late March and April. In addition to the types a total of 349 females and 93 males were examined from localities listed below (including records from the literature).
CALIFORNIA. CALAVERAS CO.: Angels Camp. COLUSA CO.: Bear Valley (9.7 mi. N of Highway 20). ELDORADO CO.: Alta. LAKE CO.: Middletown. MARIN CO.: Cypress Ridge; Fairfax; Olema (2 mi. S); Point Reyes; San Geronimo. MERGED CO.: Snelling (8 and 9 mi. NE). NAPACO.: Pope Valley (and vicinity). SACRAMENTO C0™¦ Fair Oaks. SANTA CLARA CO.: Mt. Hamilton (5 mi. E); San Antonio Valley. SAN JOAQUIN CO.: Clements. SOLANO CO.: Dozier (11-12 mi. S of Dixon); Dixon (11 mi. S); Green Valley Estates. SONOMA CO.: Agua Caliente; Santa Rosa. STANISLAUS CO.: Evergreen Road (3.2 mi. W of Highway 120); La Grange (9 and 13 mi. NW). TUOLUMNE CO.: Chinese Camp; Mather (4-5 mi. S). YOLO CO.: Davis (and 5 mi. W).
FLORAL RECORDS. — Andrena pulverea is an oligolege of flowers of the genus Limnanthes and has been collected from flowers of the plants listed below.
Baeria sp., Blennosperma nanum, Limnanthes alba alba, L. douglasii, L. douglasii var. nivea, L. rosea, Montia perfoliata, Platystemon californicus, Ranunculus sp., Raphanus sativus.
Andrena pulverea Viereck, 1917, Proc. Acad. Nat. Sci. Philadelphia, 68:569-570.
Andrena (Hesperandrena) limnanthis Timberlake, 1951, Proc. United States Nat. Mus., 101:387-388. New synonymy.
Updated: 2023-05-30 23:29:29 gmt