Reprinted with permission of the American Entomological Society from:
LaBerge, W. E., Ribble, D. W. 1972. A revision of the bees of the genus Andrena of the Western Hemisphere. Part V: Gonandrena, Geissandrena, Parandrena, Pelicandrena. Transactions of the American Entomological Society 98: 271-358.
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This small western species is similar to A. arenicola in having the vertex extremely short and flat. In facial view the vertex is just reached or surpassed by the lateral ocelli in most specimens. The female of concinnula can be separated from that of arenicola by the interrupted apical fasciae of terga 2 and 3 and by the opaque, tessellate mesoscutum. The male of concinnula is distinctive in having moderately long antennae and having the parocular yellow maculae absent or very small.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-10 mm; width, 2-3 mm; wing length, M = 3.39 ± 0.247 mm; FL/FW, M = 0.92 ± 0.004; FOVL/FOVW, M = 3.70 ± 0.044.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third rufescent; flagellum dark brown below; wing membranes hyaline, colorless to slightly milky, veins dark reddish-brown to blackish-brown; STRUCTURE. — Antennae as in andrenoides but flagellar segment 2 slightly shorter than 3 and segments 4-9 quadrate. Eyes, mandible and galea as in andrenoides. Labial palpus as in andrenoides but segmental ratio about as 1.0:0.8:0.7:0.8. Maxillary palpus as in andrenoides but ratio about as 1.0:1.0:0.8:0.8:0.7:0.8. Labral process extremely short, triangular. Clypeus strongly protuberant medially, laterally with small round punctures separated mostly by half to one puncture width or more, absent along broad, protuberant midline; surface reticularly shagreened laterally and basally, shiny medially. Supraclypeal area with minute longitudinally oriented rugulae (not much more than coarse shagreening) and sparse extremely minute punctures. Face as in andrenoides. Vertex extremely short, length equals less than half an ocellar diameter behind ocellus, in full facial view lateral ocelli usually reach or surpass vertex. Facial fovea as in andrenoides. Genal area about one and one-fourth times as broad as eye in profile, dulled by sparse minute punctures and coarse reticular shagreening which often is in rows paralleling posterior margin.
Pronotum much as in andrenoides but area above impressed oblique suture with several weak but distinct longitudinal rugulae, a few rugulae may extend below suture along inner margin of dorsoventral ridge. Mesoscutum as in andrenoides but surface opaque, regularly and coarsely tessellate. Scutellum, propodeum and mesepisternum as in andrenoides. Wing venation and tibial spurs as in andrenoides.
Metasomal terga virtually impunctate (punctures so minute as to be barely visible under high magnification); surface dulled by regular fine reticular shagreening. Pygidial plate and sterna as in andrenoides.
VESTITURE. — Generally white except as follows: facial fovea with short hairs often brown at least in upper half; face and vertex often with hairs brown, pollen-collecting hairs, tergal fasciae and sternal fimbriae as in andrenoides.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7-9 mm; width, 1.5-2.5 mm; wing length, M = 2.98 ± 0.165 mm; FL/FW, M = 0.88 ± 0.005; FS1/FS2, M = 1.69 ± 0.032.
INTEGUMENTAL COLOR. — As in female except as follows: clypeus yellow except apical margin and usually narrow area along posterior margin (yellow area usually triangular in outline); parocular areas usually black but occasionally with small yellow maculae; flagellar segments 2-11 reddish-brown to brown below.
STRUCTURE. — Antenna moderately long, in repose reaching to posterior margin of scutellum; scape as in andrenoides; flagellar segment 1 equal in length to segment 2 plus half of segment 3, segment 2 equal to about two-thirds of 3 and quadrate, segments 3-11 longer than broad. Eyes each about three times as long as broad or slightly longer, inner margins converging towards mandibles. Galea and mandible as in andrenoides. Labial palpus as in andrenoides but segmental ratio about as 1.0:0.8:0.6:0.6. Maxillary palpus as in andrenoides but ratio about as 1.0:1.0:0.8:0.7:0.5:0.7. Labral process small to minute, triangular; labrum apical to process with shallow transverse shiny sulcus but posterior border of sulcus indistinct, broad zone between sulcus and process minutely punctate. Clypeus extremely flat medially, barely protruding beyond eyes in profile; surface with small punctures laterally and posteriorly, impunctate or sparsely punctate medially; shiny except posteriorly where delicately shagreened. Supraclypeal area, face and genal area as in andrenoides. Vertex extremely short, above lateral ocellus length equals less than half an ocellar diameter behind ocellus, in full facial view lateral ocelli usually reach or surpass vertex.
Pronotum as in female but rugulae in portion below oblique suture often more abundant. Mesoscutum as in female. Propodeum and mesepisterna as in andrenoides. Wing venation and tibial spurs as in andrenoides.
Metasomal terga sculptured as in female but apical areas moderately shiny. Sterna sculptured as in andrenoides. Sternum 6 with apicolateral teeth widely separated, strongly reflexed (at right angles to surface) and slightly twisted. Terminalia as figured (Figs. 55-59): note the following: gonocoxite with dorsal lobe rounded, apical process with weak inner angle and small basoventral angular process; penis valve with both dorsal and ventral lateral lamellae of about equal size. Sternum 7 entire apically or only extremely weakly emarginate, apical hairs short and weak. Sternum 8 with apical part large, with short stout hairs.
VESTITURE. — Generally white but often with a few to many brown hairs on face above antennae and on vertex. Distribution of hairs as in andrenoides.