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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As its name indicates, annectens connects the illinoiensis species group with the piperi group (see discussion under Micrandrena). Andrena annectens has the general appearance of the piperi group but like the illinoiensis group it has slender hind tibiae in the female and an entirely black clypeus in the male. The species is probably most closely related to salictaria (of the illinoiensis group) but can be distinguished by its smaller size and in the female by the weak apical abdominal fasciae. The male has quite different and distinctive genitalia (figs. 80-82). The two species are allopatric. Andrena annectens is also related to melanochroa (of the piperi group) which has slightly widened hind tibiae in the female and a dark clypeus in the male. The width of the female hind tibiae in annectens would place it a little closer to the illinoiensis group than to the piperi group.
FEMALE. MEASUREMENTS AND RATIOS. — Length, 6.6 mm; width of mesothorax, 1.7 mm; wing length from tegula, 5.3 mm; facial length/width, 1.00; foveal length/width, 4.57.
INTEGUMENTAL COLOR. — Color as in illinoiensis except flagellum red-brown below; legs all brown.
STRUCTURE. — Head as in illinoiensis except: mandible extending nearly to opposite corner of labrum; maxillary palpus with segments in ratio of about 1.3:1.5:1.2:1.0:1.0:1.3; labial palpus with segments in ratio of about 2.0:1.0:1.0:1.2; labral process subtriangular, margin uneven; clypeus without shagreening only apically; genal area in lateral view as wide as eye.
Mesosoma as in illinoiensis except: mesepisternum sculptured like mesoscutum; serrate part of anterior tibial spur short, one-third length of entire spur; posterior hind tibial spur slightly longer than anterior spur; pterostigma very large, twice as wide as prestigma; first transverse cubital vein ending one and one-half vein widths from pterostigma.
Metasoma as in illinoiensis.
VESTITURE. — Hairs as in illinoiensis except: facial fovea more grey above; hairs on anterior mesoscutum with fewer branches; terga 2-4 with weak apical fasciae, broadly interrupted medially on tergum 2, medially reduced to a few scattered hairs on 3, complete on 4, fascial hairs much shorter than illinoiensis.
MALE. MEASUREMENTS AND RATIOS. — Length, 5.4 mm; width of mesothorax, 1.5 mm; wing length from tegula, 4.9 mm; facial length/width, 0.98; flagellar segment 1/segment 2, 1.67.
INTEGUMENTAL COLOR. — Color as in illinoiensis except: flagellum dark brown below; veins dark amber, darker than in annectens female; legs all brown.
STRUCTURE. — Head as in illinoiensis except: antenna reaching to metanotum; flagellar segment 2 slightly tapered; ultimate segment slightly more than one and one-half times as long as broad; inner eye margins distinctly convergent below; maxillary palpus with segments in ratio of about 1,2:1.5:1.0:1.2:1.0:1.3; labial palpus with segments in ratio of about 1.7:1.0:1.0:1.4; labral process about half as wide as entire labrum, not emarginate at apex; clypeus with shagreening absent except midbasally; genal area in lateral view slightly wider than eye.
Mesosoma as in illinoiensis except: scutellar shagreening less coarse than on mesoscutum; mesepisternum more coarsely sculptured than mesoscutum.
Exposed metasoma as in illinoiensis except: tergum 7 broadly rounded at apex; sternum 6 with broad apical emargination, lateroapical corners gradually and distinctly bent downward.
Sternum 7 notched at apex, producing two large rounded lobes, each lobe bearing numerous branched setae (fig. 83). Sternum 8 convex, with base expanded into large subtriangular plate; apex slightly expanded; shaft curved downward, shaft short; apical half of sternum setose, setae mostly long and branched, some setae reaching beyond apex of sternum (fig. 84). Gonocoxite bent downward at right angle; apex unevenly rounded; dorsal part of gonoforceps twice expanded, apical half of gonoforceps with weakly branched or simple setae; dorsal lobes short, wide. Penis valve bent slightly anteriorly; apex rounded, reaching much beyond tip of gonocoxite; medially expanded with posterior projecting hook (figs. 80-82).
VESTITURE. — Hairs as in illinoiensis except: facial fovea entirely absent; apical abdominal fasciae very weak, reduced to a few scattered hairs on terga 2 and 3, absent on other terga.
VARIATION. — Slight variations in the shape of the labral process in the type series was detected.