Smithsonian Institution, Entomology Department · 1
Andrena fracta, face |
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Smithsonian Institution, Entomology Department · 1
Andrena fracta, top |
Smithsonian Institution, Entomology Department · 1
Andrena fracta, side |
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Overview |
Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1969. A revision of the bees of the genus Andrena of the Western Hemisphere. Part II. Plastandrena, Aporandrena, Charitandrena. Transactions of the American Entomological Society 95: 1-47.
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This southwestern species is the smallest of our Plastandrena It is closely related to A. prunorum but can be distinguished in both sexes by the mesepisternal punctures being discrete, as described below, by its smaller size and usually darker color.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 9.5-12.0 mm width. 3.0-3.5 mm; wing length. M = 3.99 ± 0.077 mm; FL/FW, M = 0.98 ± 0.004; FOVL/FOVW, M = 3.21 ± 0.043.
INTEGUMENTAL COLOR. — Usually black except as follows: flagellar segments 3-10 brown below; tegulae reddish-brown; wing membranes hyaline with fore wings with a deeply infumate area from apex through submarginal cells nearly to base, veins red or reddish-brown; terga with apical area; translucent, yellow to brownish; sterna with apical areas hyaline, colorless distitarsi dark reddish-brown; tibial spurs dark red. Sixteen percent of females exhibit some degree of rufescence as follows: mandible rufescent; clypeus orange except peripherally or with pale median area; supraclypeal area rarely red; scapes and first one or two flagellar segments orange; pronotum partly to entirely red; mesoscutum, scutellum and metanotum partly to almost entirely red; dorsal enclosure propodeum occasionally red; mesepisterna, dorsal part of metepisterna and corbicular surface rarely red terga red apical to hyaline apical areas, black basally (except rarely terga 1 and 2 entirely red); sterna red; legs entirely red or with piceous coxae and trochanters.
STRUCTURE. — Antennal scape length equals about first three and one-half flagellar segments; segment 1 equals segments 2 and 3 plus half of 4 or slightly longer; segment 3 equals 4 and shorter than 5. Eye, malar space mandible and galea as in crataegi, Maxillary palpus as in crataegi but segmental ratio about 0.8: 1.0: 0.7; 0.7: 0.7: 0.7. Labial palpus as in crataegi but segmental ratio about 1.0: 0.5: 0.5: 0.3. Labral process as in crataegi usually entire, apical labral area without crista or with a single, median, extremely weak crista. Clypeus rounded with small round punctures laterally separated by half to one puncture width or slightly more, usually impunctate along midline and often in small apicomedian area, surface shiny, unshagreened except at extreme periphery. Supraclypeal area dull, punctures minute, crowded. Genal area broader than eye in profile, with extremely minute punctures and fine shagreening moderately dulling surface, Vertex short as in crataegi, punctures less distinct. Face above antennal fossae and facial fovea as in crataegi.
Thorax as in crataegi except as follows: propodeal dorsal enclosure with extremely weak, irregular rugulae, without transverse rugulae separating dorsal from posterior surfaces; dorsolateral and posterior surfaces propodeum finely punctate and tessellate, dull; mesepisternum with distinct, round punctures separated mostly by half to one puncture width, interpunctural spaces flat, dulled by fine tessellation. Hind femur without posteroventral ridge or carina (as in prunorum). Wing venation as in crataegi but vein 1st m-cu meets second submarginal cell at or well beyond middle of cell.
Metasomal terga and sterna as in prunorum; pygidial plate V-shaped with rounded apex. internal raised triangular area not visible except in unworn specimens where it almost coincides with margins of plate.
VESTITURE. — Generally arranged and colored as in prunorum but tends to be paler, often whitish or cinereous rather than ochraceous.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-11 mm; width, 2-3 mm; wing length, M = 3.60 ± 0.130 mm; FL/FW, M = 1.04 ± 0.004; FS1/FS2, M = 1.53 ± 0.118.
INTEGUMENTAL COLOR. — Generally as in female with the following exceptions: clypeus always lemon-yellow except narrow peripheral zone; specimens exhibiting reddened integument make up 9 percent of specimens examined and those with greatest red not so much as in female.
STRUCTURE. — Antennae in repose extend beyond tegulae but do not reach propodeum; scape length equals first two and one-half flagellar segments or less; segment 1 slightly shorter than segments 2 plus 3, segment 2 shorter than 3, segments 3-11 almost one and one-half times as long as broad. Eye, malar space, mandible and galea as in crataegi, Maxillary palpus as in crataegi but segmental ratio about 0.9: 1.0: 0.8: 0.8: 0.7: 0.5. Labial palpus as in crataegi but segmental ratio about 1.0: 0.5: 0.5: 0.5. Labral process as in female but usually slightly emarginate, apical labral area without crista. Clypeus as in female but punctures slightly more crowded and median area usually not impunctate. Supraclypeal area, genal area, vertex and face above antennal fossae as in female.
Thoracic sculpturing as in female but mesoscutum usually duller, shagreened and propodeal dorsal enclosure often simply roughened, not distinctly rugulate. Wing venation as in female and hind femur as in female.
Metasomal terga 1-5 sculptured as in female terga 1-4. Sterna 2-5 with basal area punctures separated mostly by 3 to 4 puncture widths, surface moderately shiny. Sternum 6 flat or with apical margin gently turned down, not angulate laterally; opening for terminalia not conspicuously broad.
Terminalia as in figures 14-18. Generally as in prunorum but note the following differences: gonostylus with apices more rounded in dorsal or ventral views; sternum 7 broader with apical area not elongate and basal | apodemes more acuminate; sternum 8 with neck region slightly longer.
VESTITURE. — Generally as in female but lacking pollen-collecting hairs and vestiture usually cinereous to white rather than pale ochraceous.
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Updated: 2024-04-27 01:30:37 gmt
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