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 leucomystax is a small species with distinct pronotal angles and lateral ridges in both sexes. It differs from lativentris in both sexes by having distinctly metallic green integument on the face and mesoscutum, by having the scutellum and often the posteromedial area of the mesoscutum shiny with shagreening slight or absent. The female has metasomal terga 2 and 3 with apical pale fasciae that are much as in escondida or baeriae. The male has a dense beard of long white hairs on the mostly pale yellow clypeus and sterna 2-5 short white subapical fimbriae narrowly interrupted medially (usually by less than one-third width of tergum).
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7.0-8.5 mm; width, 2.0-3.0 mm; wing length. M = 2.41 0.150 mm; FL/FW, M = 0.86 ± 0.006; FOVT / FOVW. M = ) ± 0.077.
INTEGUMENTAL COLOR. — Black except as follows: frons above antennal fossae with greenish metallic tints; mandible with apical third to half rufescent; flagellar segments 310 dark red below, segments 1 and 2 dark brown; mesoscutum with anterior third with metallic green tints; wing membranes hyaline, yellowed, veins red to reddish brown; metasomal terga hyaline apically, becoming dark towards base of apical area, usually without metallic tints basally; tibia! spurs testaceous.
STRUCTURE. — Antennal scape as in baeriae. Eyes as in baeriae but diverging slightly towards vertex. Mandibles and malar space as in escondida. Face sculptured much as in escondida and baeriae. Galeae as in escondida except surface shiny, not at all tessellate or shagreened. Maxillary palpus short as in baeriae, segmental ratio about as 1.0:0.8:0.6:0.5:0.3:0.4. Labrum as in baeriae, with process short, broad, gently emarginate apicomedially. Clypeus, supraclypeal area and face above antennal fossae as in escondida but face above antennal fossae with longitudinal rugulae relatively coarse. Facial fovea relatively short and narrow, separated from lateral ocellus by one ocellar diameter or slightly
re. Vertex above lateral ocellus equal to half an ocellar diameter. Genal area as in baeriae.
Pronotum with humeral angles and lateral ridges well formed, space posterior to lateral ridge relatively shiny. Mesoscutum usually shiny and without shagreening posteromedially, otherwise as in baeriae. Scutellum usually without shagreening, shiny, with punctures scattered peripherally (Fig. 19). Propodeum and pleurae as in escondida.
Metasomal terga sculptured much as in escondida or baeriae but tergum 1 not densely tessellate, rather coarsely shagreened, and terga 2-4 with basal areas usually moderately shiny, shagreened but not densely so. Sterna 2-5 sculptured much as in escondida.
VESTITURE. — White to pale ochraceous except as follows: facial fovea with tomentum pale brown to dark ochraceous; vertex and thoracic dorsum with hairs ochraceous to yellow; terga 2-4 with white apical fasciae, those on terga 2 and 3 narrowly interrupted medially usually by distinctly less than one-third width of tergum; terga 5 and 6 with vestiture white. Pollen collecting hairs as in escondida (Figs. 16 to 18).
MALE: MEASUREMENTS AND RATIOS. — N = 20; length, 6.0-8.0 mm; width 1.2-2.0 mm; wing length, M = 2.26 0.190 mm; FL/FW, M = 0.93 ± 0.007; FS1/FS2, M = 2.09 ± 0.034. INTEGUMENTAL COLOR. — As in female except as follows: clypeus pale yellow except narrow infuscation along posterior border and in lateral angles and dark apical border; terga 1-3 basal areas without lateral pale spots; face above antennal fossae and anterior third of mesoscutum with metallic green reflections.
STRUCTURE. — Antennae short, female-like; flagellar segment 1 as long as segments 2 and 3 together or slightly longer; segment 2 subequal in length to segment 3; segments 46 about as long as broad, remaining segments distinctly longer. Eyes, mandible, and genal area as in baeriae. Galea as in female, surface shiny, unshagreened. Maxillary palpus as in female, ratio about as 1.0:1.0:0.8:0.6:0.4:0.8. Labial palpus as in female but segmental ratio about as 1.0:0.6:0.7:0.6. Labral process somewhat recurved, distinctly toothed. Clypeus sculptured as in female, but punctures not evident due to pale color. Supraclypeal area and face above antennal fossae sculptured as in female. Vertex and genal area as in female.
Pronotum with distinct humeral angles and lateral ridges, surface anterior to ridge tessellate, dull, posterior to ridge moderately shiny. Mesoscutum usually with small posteromedian area shiny, unshagreened; scutellum usually shiny, unshagreened or relatively faintly so.
Metasomal sculpturing as in female but terga 2-5 usually slightly shinier. Sterna as in female. Sternum 7 (Fig. 30) similar to that of duboisi (Fig. 24) but apical lobes broader and slightly slanted from the apex, median emargination slightly deeper; sternum 8 (Fig, 31) with apical lobe entire, neck region much broadened posteriorly as in duboisi (Fig. 25).
VESTITURE. — White to pale ochraceous but inner surfaces of tarsi pale yellow. Metasomal terga 2-5 with white apical fasciae usually interrupted medially on terga 2-A as in baeriae. Sterna 2-5 with weak subapical fimbriae of extremely short, white, plumose hairs (as in duboisi).
TYPE MATERIAL. — The holotype female and allotype male with one female paratype of leucomystax were reared from a nest she located at 9 miles S of Dixon, Solano County, California, October 18, 1968 by B.J. Donovan. The holotype and allotype are deposited in the collection of the California Academy of Sciences.
DISTRIBUTION. — Andrena leucomystax is known (Fig. 3) only from California. In addition to the type series associated with the holotype, 27 female and 24 male paratypes (CAS, UCD, UCR, LACM, USU, INHS) from California were collected as follows:
CALIFORNIA. FRESNO CO.: Coalinga (14.5 mi. N). — 1 female. Mar. 21, 1963, J.W. MacSwain. Mendota — 4 females, March 22, 1967, R.R. Snelling; 2 males, March 14, 1957 from Baeria sp., R.R. Snelling. SANLUIS OB1SPOCO.: Simmler (15 mi. SE at south end of Soda Lake). — 1 male, March 2. 1969, H.B. Leach. SOLANO CO.: Dixon (9 mi. S). — 2 males on Layia chrysanthemoides, April 17, 1969, R.W. Thorp; 2 males, April 11, 1975, R.B. Kimsey; 1 male, April 24, 1969, R.W. Thorp; 2 females, April 27, 1949, W.F. Chamberlain on L. chrysanthemoides. Dozier (11 mi. S of Dixon). — 1 female on Blennosperma nanum Mar. 26, 1969, R.W. Thorp; 1 female, 1 male on Limnanthes douglasii, Mar 26,1969, B.J. Donovan; 1 female on Lasthenia chrysostoma, April 3, 1969, B.J. Donovan: 1 female on B. nanum. Apr. 3, 1969, D.L. Briggs; 1 female, 2 males on B. nanum, March 19, 1969, R.W. Thorp; 3 females on L. chrysostoma, Apr. 17, 1969, R.W, Thorp; 5 females on L. chrysostoma. May 1, 1969, D.L. Briggs; 1 male on B. nanum, March 8, 1969, B.J. Donovan; 1 male, April 3, 1971, R.W. Thorp; 2 males on B. nanum, March 26, 1969, B.J. Donovan; 1 male on B. nanum, April 11, 1969, B.J. Donovan; 2 males on L. chrysostoma, April 3, 1969, B.J. Donovan; 2 males, April 3,1969, J. Marsh; 1 male at nest, May 1, 1969, R.W. Thorp; 1 female on B. nanum, March 19, 1969, B.J. Donovan; 2 males on Downingia pulchella, April 24, 1969, R.W. Thorp: 1 female on Lasthenia. May 1. 1969. R.W. Thorp; 1 male at nest site, April 3, 1969. B.J. Donovan; 1 female at nest site. May 1. 1969. B.J. Donovan. STANISLAUS CO.: LaGrange — I female o\\Baeria sp., April 26. 1952. R. Snelling. TULARE CO.: Strathmore. — 1 female on Baeria tenella, March 28, 1937, P.H. Timberlake. YOLO CO.: Davis. — 1 female. May 12,1937, J.J. DuBois. Winters. — 1 female on Baeria sp., March 6, 1947, G.E. Bohart.
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