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Andrena illustris LaBerge, 1977
Life   Insecta   Hymenoptera   Apoidea   Andrenidae   Andrena
Subgenus: Thysandrena


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Overview
Reprinted with permission of the American Entomological Society from: LaBerge, W. E. 1977. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VIII. Subgenera Thysandrena, Dasyandrena, Psammandrena, Rhacandrena, Euandrena, Oxyandrena. Transactions of the American Entomological Society 103: 1-144.

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This small species from southern California is not closely related to any of the foregoing Thysandrena. It is primitive in having a coarsely sculptured propodeum much as in some of the Euandrena, but the distinct tergal banding of the w-scripta type and the well-formed male sternal fimbriae place it within the Thysandrena and probably near the base of the candida group of species. Andrena illustris can be readily recognized in either sex by having the mesoscutum entirely shiny and lacking shagreening even in the anterior third. The female of illustris has the facial foveae especially long and narrow.

FEMALE. MEASUREMENTS AND RATIOS. — N = 13; length, 8-9 mm; width, 2.0-2.5 mm; wing length, M = 3.19 ± 0.124 mm; FL/FW, M = 0.99 ± 0.005, FOVL/FOVW, M = 4.45 ± 0.092.

INTEGUMENTAL COLOR. — Generally black with faint metallic blue reflections except as follows: mandible with apical half rufescent; flagellum below brown; wing membranes hyaline, veins brown to reddish-brown; terga with apical areas translucent, rufescent except narrow hyaline rims; sterna with narrow apical areas colorless or yellow; tibial spurs pale; tarsi dark.

STRUCTURE. — Antennal scape equal in length to first three and one-half flagellar segments or slightly more; flagellar segments as in candida but segment 4-9 slightly longer than broad. Eyes each about four times as long as broad, inner margins parallel. Malar space, mandible and galea as in medionitens. Maxillary palpus as in medionitens but segmental ratio about as 1.0:1.0:0.8:0.8:0.6:0.6. Labial palpus as in medionitens but ratio about as 1.0:0.6:0.6:0.6. Labral process bidentate; labrum below process shiny with weak median crista. Clypeus rounded from side to side with distinct punctures of irregular size separated by half to one or more puncture widths, smaller and more crowded in lateral angles and along posterior margin; surface shiny, unshagreened except in narrow peripheral area. Supraclypeal area with distinct small contiguous punctures, moderately shiny. Genal area in profile slightly broader than eye, with distinct small punctures separated by two or more puncture widths, minute and sparse near eye margin, larger and crowded below, surface shiny, unshagreened. Vertex above lateral ocellus equal to about one ocellar diameter, punctatorugose, full. Face above antennal fossae with coarse longitudinal rugae reaching ocelli and coarse interrugal punctures dulling surface. Facial fovea shallow, long, narrow, separated from lateral ocellus by one ocellar diameter or slightly more, of about same breadth throughout.

Pronotum moderately dulled by fine reticular shagreening, puncture sparse throughout. Mesoscutum with distinct punctures, in anterior third separated by half a puncture width or slightly more, elsewhere separated by one to three puncture widths; surface shiny, unshagreened even in anterior third (slight shagreening may be present in lateral angles just anterior to tegulae). Scutellum similar. Metanotum with small contiguous punctures and shagreening dulling surface. Propodeum with dorsal et closure with short rugulae basomedially (holotype) or finely areolate throughout, tessellate near apex; dorsal and posterior surfaces outside enclosure tessellate with distinct punctures (holotype) to finely punctatorugose; lateral surface moderately dulled by coarse but even tessellation and scattered punctures. Mesepisternum dull, punctatorugose. Wings as in medionitens but vein 1st m-cu meets second submarginal cell usually near middle of cell.

Metasomal tergum 1 with small sparse punctures separated largely by one to two puncture widths, surface shiny, extremely faintly shagreened or not at all. Terga 2-4 similar to 1 but apical areas with punctures more crowded beneath pale apical fasciae and shagreening more distinct especially in apical areas and at extreme bases of discs. Pygidial plate V-shaped with rounded apex, raised internal triangle present, weak with apex rounded. Sterna as in medionitens but surface shiny to moderately so, shagreening weak.

VESTITURE. — Generally white except as follows: upper third of facial fovea light brown; dorsum of thorax pale ochraceous; terga 5 and 6 ochraceous at least medially; basitibial plate dark brown. Pollen-collecting hairs as in medionitens; metasomal terga 2-4 with apical pale fasciae but interrupted medially on terga 2 and 3 as in w-scripta.

MALE. MEASUREMENTS AND RATIOS. — N = 9; length, 8-9 mm; width, about 2 mm; wing length, M = 3.19 ± 0.164 mm; FL/FW, M = 1.00 ± 0.008; FS1/FS2, M = 1.20 ± 0.024.

INTEGUMENTAL COLOR. — As in female except as follows: flagellum below dark brown; distitarsi often dark rufescent at least apically.

STRUCTURE. — Antennae and eyes as in medionitens. Malar space, mandible and galea as in female. Maxillary palpus as in female but segmental ratio about as 1.0:1.0:0.7:0.7:0.7:0.6. Labial palpus as in female. Labral process deeply emarginate, moderately reflexed apically; labrum below process shiny, without crista (allotype) or crista barely discernible. Clypeus moderately flattened posteromedially, with deep round punctures separated mostly by half a puncture width or less; surface shiny, unshagreened. Supraclypeal area, vertex, genal area as in female. Face above antennal fossae as in female but rugae less distinct, coarse punctures more evident.

Thoracic form and sculpturing as in female except as follows: propodeum with dorsal enclosure areolate throughout, with dorsal and posterior surfaces outside of enclosure coarsely punctatorugose, with lateral surface densely tessellate with crowded punctures in upper half, dull. Wings as in female.

Metasomal terga and sterna as in female but tergal discs with punctures slightly more crowded. Pygidial plate vestige present, narrowly V-shaped. Sternum 6 flat with shallow apical emargination. Terminalia as in Figures 42-46

VESTITURE. — Generally white except as follows: vertex, face along margins of eyes, genal areas near eyes and in upper fourth with abundant long dark brown hairs; dorsum of thorax pale ochraceous, scutellum often with a few brown hairs medially. Terga 2-4 with interrupted pale apical fasciae; sterna 2-5 with subapical fimbriae of recurved hairs; clypeus densely haired almost as in trizonata.

Names
Scientific source:

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FamilyScientific name @ source (records)
Asteraceae  Baeria sp @ BBSL (1)
Rhamnaceae  Ceanothus greggii @ UCRC_ENT (1)
_  Withheld @ BBSL (2)

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Updated: 2024-03-28 18:57:38 gmt
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