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Andrena hemileuca Viereck, 1904
Andrena asmi Viereck, 1904; Andrena (Andrena) lummiorum Viereck, 1917

Life   Insecta   Hymenoptera   Apoidea   Andrenidae   Andrena
Subgenus: Andrena

Andrena hemileuca, head, F equals Fplus.alt
David Cappaert · 7
Andrena hemileuca, head, F equals Fplus.alt

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Andrena hemileuca FEM mm x ZS PMax
© Copyright Laurence Packer 2014 · 7
Andrena hemileuca FEM mm x ZS PMax
Andrena hemileuca MALE mm x ZS PMax
© Copyright Laurence Packer 2014 · 7
Andrena hemileuca MALE mm x ZS PMax
Overview
Reprinted with permission of the American Entomological Society from: LaBerge, W. E. 1980. A revision of the bees of the genus Andrena of the Western Hemisphere. Part X. Subgenus Andrena. Transactions of the American Entomological Society 106: 395-526.

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Andrena hemileuca is a small to medium-sized, highly variable species from the west coast; It is closely related to A; rufosignata and clearly related to A; schuhi and related species; The female of hemileuca is like that of buckelli or saccata in lacking inferior mandibular teeth; This female resembles that of rufosignata in the relatively long facial quadrangle and malar space but differs in the small, but distinct, depression in the vertex (facial view) above the middle ocellus; The clypeal punctures are usually coarse and the facial rugulae below the ocelli usually diverge towards the ocelli; The male of hemileuca is very similar to that of schuhi or milwaukeensis in general color, flat sixth sternum and basal inferior mandibular teeth but differs in the facial rugulae being strongly divergent towards the ocelli, the moderately long to long malar space and the usually coarse clypeal punctation; The female varies in color from the vestiture being mostly white to ochraceous (as in most rufosignata) to specimens with the head, pleurae and abdominal segments 2-6 dark brown; The scopal hairs of the hind tibiae usually have pale hairs along the anterior margin but may be mostly pale to entirely brown; No geographical trend seems to exist among these color variations; In most species of Andrena in which the males have basal inferior mandibular teeth, such teeth can be seen in the females as well, although they may be extremely small; hemileuca is exceptional in that the female completely lacks such teeth while the males have them well-formed.

FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 9-12 mm; width, 2.5-3.5 mm; wing length, M = 4.13 ± 0.228 mm; FL/FW, M = 1.04 ± 0.011; FOVL/FOVW, M = 3.17 ± 0.055.

INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third or more rufescent; flagellar segments 2-10 below dark brown to dark reddish-brown; tegula somewhat translucent posteriorly; wing membranes slightly to moderately infumate, veins dark brown to black; tibial spurs testaceous to light brown; distitarsi dark rufescent; terga and sterna with apical areas usually with rufescent reflections.

STRUCTURE. — Antennal scape length equals first two and three-fourths flagellar segments; flagellar segment 1 about as long as following two segments, segment 2 slightly shorter than 3 and usually about as long as broad; Eyes each almost four times as long as broad, inner margins parallel; Mandible as in vicinoides, base without inferior tooth; Malar space long, as in rufosignata; Galea pointed, outer-apical margin straight or almost so, dull, finely tessellate; Maxillary palpus as in frigida but segmental ratio about as 0.9:1.0:0.9:0.9:0.8:0.8; Labial palpus as in frigida but ratio about as 1.0:0.6:0.7:0.7; Labral process bidentate, shiny, base flat; labrum apical to process flat with weak median crista, shiny; Clypeus protrudes beyond level of lower margins eyes by half its length or more; coarsely punctate except apicomedially and along impunctate midline, surface usually shiny except basally (much as in rufosignata but punctures usually coarser); Supraclypeal area dulled, finely rugatulopunctate and shagreened; Face above antennal fossae with longitudinal rugulae which below ocelli distinctly diverge towards ocelli; Facial fovea as in frigida but separated from lateral ocellus by about three-fourths an ocellar diameter; Vertex short, above lateral ocellus usually slightly shorter than one ocellar diameter, upper margin sharp with a slightly but distinct median emargination; Genal area in profile as broad as eye or slightly broader, shiny near eye margins, shagreened posteriorly, with minute sparse punctures; Thoracic form and sculpturing as in vicinoides but propodeum with dorsal enclosure usually roughened across base.

Metasomal terga as in vicinoides but basal area punctures sparse, minute, usually virtually impunctate; terga 2-4 with apical areas practically impunctate, shagreening weak, shinier than basal areas; Sterna as in vicinoides; Pygidial plate V-shaped with rounded apex and raised internal triangular area.

VESTITURE. — Pale specimens with vestiture pale ochraceous except as follows: facial fovea dark brown; facial hairs surrounding antennal fossae and on vertex dark brown; fore and middle tibiae and tarsi and hind tarsi with outer surfaces dark brown; tibial scopal hairs white except on and below basitibial plate brown (often entire posterior half of tibia with dark brown scopal hairs); inner surfaces tarsi reddish-brown; terga 5 and 6 with brown hairs); tergum 4 and occasionally tergum 3 with basal areas with some brown hairs mixed with mostly pale; sterna 3 and 4 with basal area hairs brown; sterna 5 and 6 dark brown; The darkest specimens have the head, thoracic pleurae and abdomen except tergum 1 entirely dark brown; scopal hairs dark brown except a few pale along anterior margin; All intergrades occur between palest and darkest forms with no geographical dines discernible; Pollen-collecting hairs as in vicinoides.

MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7-9 mm; width, 1.5-2.0 mm; wing length, M = 3.43 ± 0.170 mm; FL/FW, M = 1.01 ± 0.008; FS1/FS2, 1.19 ± 0.021.

STRUCTURE. — Antennal scape usually only slightly longer than first two flagellar segments; flagellar segment 1 usually slightly longer than segment 2 which is shorter than 3 and longer than broad; Eyes each about three and one-half times as long as broad, inner margins parallel; Mandibles as in vicinoides but basal inferior teeth usually larger; Malar space long, minimum length one-third basal mandibular width or longer; Galea as in female; Maxillary palpus as in female but segmental ratio about as 1.0:0.9:0.8:0.8:0.8:0.8; Labial palpus as in female but ratio about as 1.0:0.5:0.6:0.6; Labral process bidentate, reflexed, shiny; labrum apical to process shiny, without distinct median crista; Clypeus moderately flattened apicomedially, elongate as in milwaukeensis, punctures usually coarse, with or without median impunctate line, usually punctures sparser apicomedially; surface dulled by reticular shagreening at least basally; Supraclypeal area as in female; Face above antennal fossae with distinct rugulae, below ocelli rugulae strongly diverging towards ocelli; Vertex as in female but median emargination often absent, usually weak; Genal area laterally as in vicinoides; Thoracic form and sculpturing as in female but pronotal ridge sharp and area posterior to ridge shiny.

Metasomal terga as in female, virtually impunctate, usually shinier, especially in apical areas; Pseudopygidial area of tergum 7 extremely narrow or absent; Sterna 2-5 as in vicinoides; Sternum 6 flat as in schuhi or milwaukeensis.

Terminalia as in figures 107-111.

VESTITURE. — Usually head hair dark brown except face surrounding antennal fossae, medially on clypeus and posteriorly on genal areas; Pale specimens have dark hairs restricted to vertex and along inner margins compound eyes; Pale specimens with thoracic hair pale ochraceous; dark forms with pleurae and lateral surfaces propodeum with varying amounts of dark hairs mixed with pale (propodeum especially dark); Pale specimens with terga 3-5 with basal areas with some dark hairs and terga 6 and 7 with brown hairs; dark specimens with tergal and sternal hairs brown except tergum 1; Legs with pale hairs.

Names
Scientific source:

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FamilyScientific name @ source (records)
Rhamnaceae  Rhamnus californica @ UCRC_ENT (1)
Saxifragaceae  Ribes inerme @ UCRC_ENT (1)

Ribes nevadense @ UCRC_ENT (15)

Ribes roezlii @ UCRC_ENT (2)

Ribes @ UCRC_ENT (6)
_  Withheld @ BBSL__YOSE (7); BBSL (34)

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Updated: 2024-03-28 15:31:34 gmt
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