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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This species is very similar to vandykei but can be distinguished by the appearance of the clypeus. The clypeus extends ventrally much more than it does in vandykei. The females appear long-headed rather than wide-headed as in vandykei. In arctostaphylae the serrate apical part of the anterior tibial spur is very short. In vandykei it is long, approaching the normal Andrena condition. The pterostigmata are narrower than is normally found in vandykei. The male antennae are much longer than in vandykei (this difference exists between the females but is less noticeable). In the males of arctostaphylae the depressed suture running across the posterior pronotal lobe ends below the humeral angle. In vandykei this deep suture crosses the humeral angle and turns anteriorly, nearly reaching the anterior margin of the pronotum.
FEMALE. MEASUREMENTS AND RATIOS. — Length, 7.5 mm; width of mesothorax, 2.1 mm; wing length from tegula, 6.1 mm; facial length/width, 1.00; foveal length/width, 2.57.
INTEGUMENTAL COLOR. — Color as in vandykei.
STRUCTURE. — Head as in vandykei except: flagellar segment 1 slightly shorter than 2 and 3 together; segment 2 equal to 3 in length, slightly shorter than 4; middle segments much longer than wide; inner eye margins slightly divergent below; apex of mandible rounded, subapical tooth rounded; maxillary palpus with segments in ratio of about 1.4:1.6:1.2:1.1:1.0:1.1; labial palpus with segments in ratio of about 2.4:1.1:1.0:1.4; labral process two-thirds as wide as entire labrum; clypeus extending ventrally past level of lower eye margins; genal area slightly wider than eye.
Mesosoma as in vandykei except: suture crossing base of posterior pronotal lobe not turning anteriorly; enclosure of propodeum not granular basally; apex of anterior tibial spur reduced to a small spine; pterostigma very large, nearly twice as wide as prestigma; first transverse cubital vein ending two vein widths from pterostigma.
Metasoma as in vandykei except pygidial plate with edges slightly upturned, central portion of plate distinctly elevated.
VESTITURE. — Hairs as in vandykei except apical abdominal fasciae weak but distinct on terga 2-4.
MALE. MEASUREMENTS AND RATIOS. — Length, 6.8 mm; width of mesothorax, 1.6 mm; wing length from tegula, 5.8 mm; facial length/width, 0.84; flagellar segment 1/segment 2, 1.00. INTEGUMENTAL COLOR. — Color as in vandykei.
STRUCTURE. — Head as in vandykei except: scape distinctly shorter than flagellar segments 1-3; segment 1 as long as 2, slightly shorter than 3; middle segments one and one-half times as long as broad; ultimate segment more than twice as long as broad; eye about three and one-half times as long as broad in anterior view; mandible and subapical mandibular tooth less pointed than in vandykei; maxillary palpus with segments in ratio of about 1.1:1.2:1.0:1.4:1.2:1.2; labial palpus with segments in ratio of about 2.2:1.0:1.0:1.3; labrum slightly more than one and one-half times as wide as long; clypeus two and one-half times as broad as long, shagreening absent only in center of yellow maculation, shagreening coarser than vandykei.
Mesosoma as in vandykei except suture extending vertically from leg base terminating just below humeral angle.
Metasoma as in vandykei except sternum 6 with apex emarginate, flexed downward.
Sternum 7 deeply notched at apex, producing two large pointed processes, each process with few setae, sternum unshagreened (fig. 98). Sternum 8 (fig. 99) very similar to vandykei. Gonocoxite relatively wide, bent downward; gonoforceps much expanded near middle in side view, dorsal surface with many weakly branched setae; dorsal lobes in dorsal view long, narrow at apex. Penis valve bent downward, apex expanded in side view; considerably expanded medially (figs. 95-97).
VESTITURE. — Hairs as in vandykei.
VARIATION. — The few specimens examined of this species are exceedingly similar and only minor individual variation was noticed. The one exception being in the color of the underside of the flagellum. The females not included in the type series have the flagellum orange below rather than being dark.