Smithsonian Institution, Entomology Department · 1
Andrena microchlora, face |
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Smithsonian Institution, Entomology Department · 1
Andrena microchlora, top |
Smithsonian Institution, Entomology Department · 1
Andrena microchlora, side |
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Smithsonian Institution, Entomology Department · 1
Andrena microchlora, wing |
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Overview |
Reprinted with permission from the University of Nebraska State Museum from:
Ribble, D. W. 1968. Revisions of two subgenera of Andrena, Micrandrena Ashmead and Derandrena new subgenus (Hymenoptera: Apoidea). Bulletin of the University of Nebraska State Museum 8: 1-124.
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Specimens bearing determination labels indicate that microchlora is occasionally confused with chlorogaster. Some of the paratypes of microchlora subalia are chlorogaster. Cockerell probably described subalia because of the inclusion of this extraneous material (Timberlake, 1951). Later Cockerell (1939) raised subalia to specific rank on the basis of a chlorogaster specimen. Linsley (1951) synonymized subalia with microchlora (s. str.), but Timberlake (1951) considered subalia a race of microchlora on the basis of male hair color. Here subalia is considered a synonym of microchlora (see Variation).
As the name implies microchlora is a small greenish Andrena. The second and third flagellar segments are noticeably shorter than the others and are slightly tapered basally. The female tibial scopa is very broad with short spreading hairs (like Scaphandrena). The male has a yellow clypeus and unusually shaped gonocoxites (figs. 56, 38).
The descriptions below are based on a male and a female from Cool, California, March 21, 1962, J. Powell, on Arenaria californica. Four hundred and twelve specimens of microchlora were examined during this study.
FEMALE. MEASUREMENTS AND RATIOS. — Length, 7.0 mm; width of mesothorax, 1.8 mm; wing length from tegula, 5.0 mm; facial length/width, 0.96; foveal length/width, 3.0.
INTEGUMENTAL COLOR. — Head, thorax and abdominal terga with blue-green reflections; integument otherwise dark brown or black except: tip of mandible deep red; eye grey; clypeus with purplish reflections; wings amber; veins and pterostigma dark amber; tegula dark amber; terga and sterna with amber apices; tibial spurs light amber; claws amber.
STRUCTURE. — Sculpturing in general finer over entire body than in piperi. Head otherwise as in piperi except: scape nearly as long as flagellar segments 1-5; flagellar segment 1 nearly as long as segments 2-4; eye about three and one-half times as long as broad in anterior view; maxillary palpus with segments in ratio of about 1.8:2.0:1.4:1.2:1.0:1.4; labial palpus with segments in ratio of about 3.3:1.0:1.3:2.0; process of labrum one-third as wide as and half as long as entire labrum; genal area in lateral view slightly wider than eye.
Mesosoma as in piperi except: posterior and dorsolateral surfaces of propodeum not raised above enclosure; hind tibia broadened, half again as wide as basitarsus. Metasoma as in piperi.
VESTITURE. — Hairs as in piperi except: hairs on dorsal half of body with a yellowish tinge, those of thorax long, not giving mesoscutum a moss-like appearance; terga 1-4 hairs (except apical fasciae) less plumose, abdomen not having the marked dusty appearance of piperi; apical fasciae absent on tergum 1, interrupted medially on terga 2, partly interrupted on 3, complete on 4; tibial scopal hairs short, hairs not overlapping, spreading outward, not orientated in same direction, making tibial surface easily visible, posterior- and anterior-most hairs may have a few branches and curve slightly posteriorly.
MALE. MEASUREMENTS AND RATIOS. — Length, 5.5 mm; width of mesothorax, 1.5 mm; wing length from tegula, 4.3 mm; facial length/width, 0.96; flagellar segment 1/segment 2, 2.3.
INTEGUMENTAL COLOR. — Head, thorax and abdominal terga with blue-green reflections; integument otherwise brown to dark brown except for the areas mentioned under piperi.
STRUCTURE. — Sculpturing in general finer over entire body than in piperi. Head otherwise as in piperi except: scape reaching to within two and one-half ocellar distances of medium ocellus, noticeably longer than flagellar segments 1-3; segment 1 nearly twice as long as 2, half again as long as 3; segment 2 tapered toward base; middle segments about as long as wide; eye about two and one-half times as long as broad in anterior view; maxillary palpus with segments in ratio of about 1.0:1.5:1.2:1.2:1.0:1.3; labial palpus with segments in ratio of about 2.7:1.7:1.0:2.0; labral process truncate at tip; clypeus moderately shiny, surface with moderate reticular shagreening.
Mesosoma as in microchlora female except hind tibia unmodified.
Exposed metasoma as in piperi.
Sternum 7 distinctly emarginate at apex, producing two rounded lobes, each lobe bearing several long, branched setae (fig. 39). Sternum 8 (fig. 40) much like piperi except basal plate different in outline. Gonocoxite bent downward; apex expanded in lateral and dorsal views, dorsolateral part with many branched setae; dorsal lobes very much reduced. Penis valve bent downward, apex rounded in lateral view, medially greatly expanded (figs. 36-38).
VESTITURE. — Hairs as in piperi except: apical abdominal fasciae absent on tergum 1, interrupted on 2, partially interrupted on 3, complete on 4 and 5.
VARIATION. — Timberlake (1951) considered subalia a race of microchlora because "the males from the Pacific coast have much black hair on the sides of the face and behind the summits of eyes. The examination of more material shows that males with dark hair occur throughout the range of microchlora. Female hair color may vary from nearly all white to yellowish on the head, mesoscutum and abdominal terga or even to specimens having many brown hairs on the head and thorax. Although these females with the brown hairs from the northern San Francisco peninsula tend also to be larger than specimens from other areas, intermediates do occur.
The female labral process varies from broadly rounded to truncate at the apex and the apex of the female antenna may be dark or orange-brown below. The enclosure of the propodeum in both sexes is sometimes nearly smooth, at other times it has many distinct rugulae. The male clypeus may be nearly all yellow or the yellow may be lacking near the base and at the sides of the clypeus. There is no reason to name the continuous variation listed above.
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Updated: 2024-04-24 03:05:33 gmt
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