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Andrena semipunctata Cockerell, 1902
Life   Insecta   Hymenoptera   Apoidea   Andrenidae   Andrena
Subgenus: Trachandrena

Andrena semipunctata, female, face
Smithsonian Institution, Entomology Department · 9
Andrena semipunctata, female, face

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Andrena semipunctata, female, side
Smithsonian Institution, Entomology Department · 9
Andrena semipunctata, female, side
Andrena semipunctata, female, top
Smithsonian Institution, Entomology Department · 9
Andrena semipunctata, female, top

Andrena semipunctata, female, wing
Smithsonian Institution, Entomology Department · 9
Andrena semipunctata, female, wing
Andrena semipunctata, face
Smithsonian Institution, Entomology Department · 1
Andrena semipunctata, face

Andrena semipunctata, side
Smithsonian Institution, Entomology Department · 1
Andrena semipunctata, side
Andrena semipunctata, top
Smithsonian Institution, Entomology Department · 1
Andrena semipunctata, top

Andrena semipunctata, wing
Smithsonian Institution, Entomology Department · 1
Andrena semipunctata, wing
Overview
Reprinted with permission of the American Entomological Society from: LaBerge, W. E. 1973. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VI. Subgenus Trachandrena. Transactions of the American Entomological Society 99: 235-371.

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This small western bee is closely related to A. mariae and A. striatifrons. The female of semipunctata differs from that of mariae by having terga 2-4 with short basal areas as in striatifrons. It differs from the female of striatifrons by its smaller average size, opaque mesoscutum and larger space between the facial fovea and the lateral ocellus. A. semipunctata differs from mariae and striatifrons in never having red-abdomened forms in either sex. The male of semipunctata can be recognized by its short first flagellar segment and dull mesoscutum, as described below.

FEMALE. MEASUREMENTS AND RATIOS. N = 20; length, 9-11 mm; width, 2.5-3.0 mm; wing length, M = 3.72 0.243 mm; FL/FW, M = 0.98 0.038; FOVL/FOVW, M = 3.69 0.047.

INTEGUMENTAL COLOR. Black except as follows: mandible with apical two-fifths rufescent; flagellar segments 2- or 3-10 brownish-black below; tegulae piceous; wing membranes hyaline, veins black to reddish-brown; distitarsi often rufescent (basitarsi never orange-red as in mariae or striatifrons;, tibial spurs yellow to rufescent.

STRUCTURE. Antennal scape length equals first four flagellar segments; flagellar segment 1 slightly shorter than segments 2 plus 3, segment 2 equal to 3 and each shorter than 4, segments 2 and 3 broader than long, 4-9 quadrate. Eyes each about three and three-fourths times as long as broad, inner margins converging slightly towards mandibles. Malar space, mandibles and galeae as in sigmundi. Maxillary palpus as in sigmundi but segmental ratio about as 1.0:1.0:0.9:0.7:0.6:0.7. Labial palpus as in sigmundi but ratio about as 1.0:0.6:0.4:0.5. Labral process trapezoidal or triangular with rounded apex, entire; labrum below process punctate, without sulcus, cristae extremely weak or absent. Clypeus as in sigmundi but without median impunctate line or this represented by a short subapical line. Supraclypeal area with small crowded punctures, surface usually shiny. Genal area laterally with small round punctures separated by half to one puncture width, without rugulae except near mandibular base, surface moderately dulled by fine shagreening, ventrally with rugulae as in mariae. Vertex above lateral ocellus equals slightly less than one ocellar diameter, dulled by crowded punctures and fine tessellation. Face above antennal fossae with coarse longitudinal rugae and sparse punctures (as in striatifrons), surface moderately dulled by fine shagreening. Facial fovea as in mariae but separated from lateral ocellus by slightly more than one ocellar width.

Pronotum as in sigmundi. Mesoscutum with coarse deep punctures, except in small posteromedial area separated by half to one puncture width, sparse posteromedially, surface opaque, coarsely and regularly tessellate. Scutellum similar but slightly shinier. Mesepisternum coarsely punctatorugose, surface dulled by fine tessellation. Propodeum with dorsal area sculptured as in striatifrons; dorsolateral and posterior surfaces coarsely rugatulopunctate, surfaces tessellate; lateral surfaces short-rugose as in striatifrons. Pterostigma, wing venation, fore femur and tibial spurs as in striatifrons.

Metasomal terga and sterna with form and sculpturing as in striatifrons but terga often less shiny especially in apical areas, usually with coarsely reticular shagreening. Pygidial plate as in striatifrons but apex blunter, rounded and internal triangular area separated from margins by twice distance found in striatifrons.

VESTITURE. Generally white to pale ochraceous except as follows: facial foveae often with short internal hairs brown; terga 5 and 6 with hairs usually brown at least medially; inner surfaces basitarsi often reddish-brown. Hair form and distribution as in striatifrons but somewhat shorter, terga 2-4 with basal area hairs short and sparse, apical lateral patches of white pubescence large and conspicuous.

MALE. MEASUREMENTS AND RATIOS. N = 20; length, 7-9 mm; width, 1.5-2.5 mm; wing length, M = 3.28 0.239 mm; FL/FW, M = 1.03 0.006; FS1/FS2, M = 0.67 0.010.

INTEGUMENTAL COLOR. Generally black except as follows: mandible with apical fourth rufescent; flagellar segments 2-11 dark blackish-brown to brown below; wing membranes hyaline, veins dark reddish-brown to black; tegulae piceous; distitarsi often rufescent (basitarsi never orange-red as in marine or striatifrons).

STRUCTURE. Antennae in repose barely reaching propodeum; scape length equals first two flagellar segments or slightly more; flagellar segment 1 distinctly shorter than 2, segments 2-10 about one and one-half times as long as broad. Eyes each about three and one-third times as long as broad, inner margins converging towards mandibles. Malar space, mandible and galea as in sigmundi. Maxillary palpus as in sigmundi but segmental ratio about as 1.0:0.7:0.6:0.6:0.6:0.6. Labial palpus as in sigmundi but ratio about as 1.0:0.6:0.4:0.6. Labral process trapezoidal, usually weakly emarginate, labrum below process dulled by fine punctures and shagreening. Clypeus and supraclypeal area sculptured as in female but median impunctate clypeal line usually absent and surfaces often slightly dulled by fine irregular shagreening. Genal area and vertex as in female. Face above antennal fossae coarsely punctatorugose, longitudinal rugulae often present at least laterally, surface dulled by fine tessellation.

Pronotum as in sigmundi. Mesoscutum, scutellum and mesepisternum sculptured as in female but punctures smaller. Propodeum sculptured as in female except as follows: dorsal area rugae often slightly coarser; lateral surface punctatorugose. Wing venation, pterostigma and tibial spurs as in female.

Metasomal terga and sterna with form and sculpture as in striatifrons but basal areas terga often more sparsely punctate and apical areas terga usually dulled by coarsely reticular shagreening. Sternum 6 broadly and shallowly emarginate apically. Terminalia as in sigmundi; see figures 44-45.

VESTITURE. Generally white to pale ochraceous; inner surfaces basitarsi pale yellow; sterna 2-5 with weak apical fimbriae of short depressed white pubescence. Form of hairs generally as in mariae.

REMARKS. A. semipunctata, A. mariae and A. striatifrons seem to replace each other geographically (see Figs. 9 and 10). Even locally these three species, all oligoleges of Salix spp., do not seem to be in competition by virtue of occurring in different areas. A. mariae is the eastern species but occurs in some areas of the Rocky Mountains and to the West Coast in the north. Where it overlaps the general range of A. striatifrons, mariae seems to occur only at lower altitudes. A. striatifrons, on the other hand, appears to occur only at high altitudes in mountainous areas, except where either mariae or semipunctata do not occur. The range of semipunctata seems to overlap that of striatifrons in parts of California, Oregon and Washington, but, like mariae, appears to occur at lower altitudes than does striatifrons. A. semipunctata may be in direct competition with mariae in the Pacific northwest and in southwestern Utah. Factors affecting this ecological and geographical separation of related species, if it exists in reality, should be studied. An ideal area for such a project would be in Oregon, especially in the vicinity of Corvallis where all three species are known to occur.

Names
Scientific source:

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Hosts · map
FamilyScientific name @ source (records)
Polycitoridae  Salix sp @ BBSL (6)
Salicaceae  Salix nigra @ AMNH_BEE (1)

Salix @ RUAC_ENT (1); AMNH_BEE (1)
_  Withheld @ BBSL (5); BBSL__PINN (1)

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Updated: 2019-10-18 01:23:47 gmt
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