Reprinted with permission of the American Entomological Society from:
LaBerge, W. E., Ribble, D. W. 1975. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VII. Subgenus Euandrena. Transactions of the American Entomological Society 101: 371-446.
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This is a common colorful western bee. Although both sexes of chlorura have metallic integumental reflections, these are usually less intense than in nigrocaerulea and usually more green or even golden, rather than blue. Both sexes of chlorura can be readily separated from those of nigrihirta by the metallic tints of the integument and they differ from those of algida by the more sparsely punctate clypeus as described below.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-10 nun; width, 2.5-3.5 mm; wing length, M = 3.67 ± 0.208 mm; Fl./FW, M = 0.98 ± 0.007; FOVL/FOVW, M = 3.S8 ± O.I 18.
INTEGUMENTAL COLOR. — Black except as follows: with metallic green or golden reflections especially on head and thoracic dorsum, terga with weak reflections (clypeus often with violaceous reflections); mandible with apical third or less usually rufescent; flagellum dark reddish-brown below, especially last four or five segments; tegulae piceous to dark red; wing membranes hyaline, only slightly infumate apically, veins and stigma dark brown; terga 2-4 with apical margins hyaline, colorless to yellow; distitarsi dark rufescent.
STRUCTURE. — Antennal scape equals first three and one-half flagellar segments or slightly less; flagellar segment 1 slightly longer than segment 2 plus 3, segment 2 usually slightly longer than 3. broader than long, remaining segments as in nigrihirta. Eyes, malar space, mandible and galea as in nigrihirta. Maxillary palpus as in nigrihirta but segmental ratio about as 1.0:1.0:0.9:1.0:1.0:0.9. Labial palpus as in nigrihirta but ratio about as 1.0:0.7:0.6:0.7. Labral process entire, margin rounded, usually with extremely weak, transverse rugulae near apex. rarely extremely shallowly emarginate; labrum below process as in nigrihirta but usually with many weak cristae. Clypeus relatively flat, evenly rounded from side to side, not markedly flattened medially, not markedly protuberant; punctures round, relatively sparse, separated irregularly by one-half to two or more puncture widths, more crowded and smaller peripherally; surface often dulled or moderately dulled by fine reticular shagreening (densely shagreened in narrow posterior area). Supraclypeal area dulled by small crowded punctures and fine dense shagreening. Genal area in profile slightly broader to one and one-third times as broad as eye: surface dulled by coarse tessellation (except along eye margin) and sparse, obscure punctures. Vertex above lateral ocellus usually distinctly shorter than one ocellar diameter (usually about as 4:7); finely tessellate with scattered punctures. Face above antennal fossae moderately dulled by longitudinal rugulae which usually reach lateral ocelli and scattered interrugal punctures. Facial fovea shallow, narrow, short; extending down about to level of lower margins antennal fossae, separated from lateral ocelli by more than one ocellar diameter (usually about as 10:7).
Pronotum normal. Mesoscutum usually opaque, with fine tessellation and scattered obscure punctures, rarely shiny in small posteromedian area. Scutellum similar to mesoscutum but somewhat shinier. Metanotum and propodeum as in nigrihirta but dorsal triangle of propodeum smoother, tessellate. mesepisterna coarsely tessellate, dull. punctures minute, sparse, obscure. Wing venation and vannal lobe as in nigrihirta.
Metasomal terga 1-5 dulled by coarse reticulotransverse shagreening. will) obscure, minute, scattered punctures, surfaces along basal margin of apical area usually slightly shinier and less shagreened than more basally. Pygidial plate V-shaped with rounded apex, raised internal triangle usually low and obscure apically. Sterna moderately shiny, with distinct round punctures separated mostly by one to two puncture widths except basally and in impunctate apical area, reticular shagreening delicate.
VESTITURE. — Ochraceous except as follows: facial fovea with short dark brown hairs; face from vertex almost to antennal fossae usually with long dark hairs (at least a few dark hairs present surrounding facial foveae in palest specimens); dorsum of thorax and vertex often will dull red hairs (at least darker ochraceous than elsewhere); terga 5 and 6 (except laterally) with long brown hairs; inner surfaces tarsi yellow; basitibial plates and below brown. Distribution of pollen-collecting hairs as in nigrihirta. Terga 1-5 with apical pale fasciae weak, thin, interrupted medially (rarely complete). Sterna without subapical fimbriae.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 6-9 mm; width, 1.5-2.5 mm; wing length, M = 3.34 ± 0.157 mm; FL/FW, M = 0.98 ± 0.007; FS1/FS2, M = 1.17 ± 0.025.
INTEGUMENTAL COLOR. — Black with same exceptions as in female.
STRUCTURE. — Antennae moderately long, in repose reaching back to anterior margin of propodeum; scape length equals slightly more than first two flagellar segments; flagellar segment 1 usually slightly longer than segment 2; flagellar segments all longer than broad, median segments almost or quite one and one-half times as long as broad. Eyes, malar space, mandible and galea as in nigrihirta. Maxillary palpus as in nigrihirta but segmental ratio about as 1.0:1.0:0.9:0.8:0.6:0.8. Labial palpus as in nigrihirta but ratio about as 1.0:0.6:0.4:0.6. Labral process usually weakly emarginate apically, rarely bidentate, shiny; labrum below process shiny, without cristae. Clypeus as in female but often apicomedian half or less shiny, shagreening weak or absent. Supraclypeal area, genal area, vertex and face above antennal fossae as in female but genal area usually slightly broader in profile.
Thoracic sculpturing as in female but lateral surfaces propodeum densely tessellate and dull (as in mesepisternum) and mesoscutum rarely shiny posteromedially. Wing venation and form of vannal lobe as in female.
Metasomal terga and sterna sculptured as in female but sterna usually shinier. Sternum 6 with apical margin shallowly concave when viewed from below. Terminalia as in figures 30-34; note the following: genital capsule much as in algida; sternum 7 with apical lobes acute; sternum 8 truncate apically.
VESTITURE. — Generally pale ochraceous to yellow, somewhat darker on vertex and thoracic dorsum, except as follows; face from vertex to antennal fossae and along side of compound eye and genal area along eye margin with long brown hairs, more rarely most of head hairs dark brown except surrounding antennal fossae, on clypeus and on lower part of genal area; scutellum, mesoscutum posteromedially, tegulae and dorsal area of mesepisterna often with dark brown hairs, terga 6 and 7 usually with a few brown hairs mixed with the pale; inner surfaces tarsi golden. Terga 2-5 with apical pale pubescent bands extremely weak, thin, interrupted medially, basal area hairs short, erect, pale (long on tergum 1 and medially on tergum 2). Sterna 2-5 with pale subapical fimbriae lacking or extremely weak and incomplete laterally. Sternum 6 without dense apical pubescent fringe.
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