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Reprinted with permission of the University of Nebraska State Museum from:|
LaBerge, W. E. 1967. A revision of the bees of the genus Andrena of the Western Hemisphere. Part I. Callandrena (Hymenoptera: Andrenidae). Bulletin of the University of Nebraska State Museum 7: 1-316.
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A. irrasus is medium-sized species from the Great Plains and eastern Rocky Mountain area. It is closely related to A. braccata Viereck. The female of irrasus can be distinguished from that of braccata by the short, shiny, coarsely punctate clypeus, the narrow short facial foveae, and the slightly more punctate terga. The female of irrasus differs from that of helianthi by the broader area between the facial fovea and the lateral ocellus, in sculpturing of the propodeum and terga, and in the sculpturing and hairs of the mesonotum as described below. The male of irrasus is very similar to that of braccata but can be differentiated by the more coarsely punctate clypeus and metasomal terga and by the basitarsus being piceous, or at most dark reddish-brown.
FEMALE. MEASUREMENTS AND RATIOS. N = 5; length, 11.0-13.0 mm; width, 3.5-4.5 mm; wing length, M = 3.91 ą 0.284 mm; PL/FW, M = 0.97 ą 0.035; FOVL/FOVW, M = 2.98 ą 0.142.
INTEGUMENTAL COLOR. Black except as follows: flagellar segments 3-10 slightly rufescent below; mandibles rufescent; tegulae slightly rufescent; wing membranes slightly infumate, yellowish; tergal apical areas slightly rufescent; sternal apical areas hyaline, yellow; distitarsi rufescent, basitarsi slightly rufescent; tibial spurs yellow.
STRUCTURE. Scape distinctly longer than flagellar segments 1-3; flagellar segment 1 equal in length to segments 2 plus 3 plus half of 4, segments 2 slightly shorter than 3, each shorter than segment 4. Eye narrow, about four times as long as broad, inner margins converging slightly toward mandibles. Malar space linear, more than six times broader than long. Outer mandible in repose exceeding middle of labrum by about one-fourth its own length, bidentate, ventrobasal lamella poorly developed. Galea and maxillary palpus as in helianthi but galea shorter and palpal segments in ratio of about 1.3:1.2:1.0:1.0:0.8:1.9. Labial palpus as in helianthi but segments in ratio of about 2.0:1.0:1.0:1.2. Labral process subrhomboidal in outline, usually entire, occasionally extremely shallowly emarginate. Clypeus gently rounded; protruding beyond ends of eyes by about one-third median clypeal length; punctures coarse, round, separated mostly by one-half puncture width except in median impunctate area which is about 3 to 4 punctures wide, surface shiny, unshagreened except peripherally. Supraclypeal area with rounded, deep punctures, surface moderately shiny, finely shagreened. Genal area broader than eye as in helianthi, punctures near eye margin small, separated mostly by one to two puncture widths, posteriorly larger but sparser, surface moderately shiny, reticularly shagreened. Vertex as in braccata except punctures more abundant, tessellation and punctures especially crowded and distinct just above facial foveae. Face above antennal fossae with fine, irregular, longitudinal rugulae, reaching ocelli and extending above facial foveae laterally. Facial fovea short, extending below to about middle of antennal fossa, upper end rounded, separated from lateral ocellus by about one ocellar diameter, lower end narrower, rounded.
Pronotum normal, with minute punctures, dorsally separated by one to two puncture widths, sparser laterally, surface dull, tessellate. Mesoscutum with coarse round punctures, medially separated mostly by two to three puncture widths, crowded peripherally, surface shiny posteromedially, dulled by coarse tessellation elsewhere. Mesoscutum similar, punctures somewhat more abundant medially, moderately shiny. Metanotum similar, punctures crowded, completely dulled. Propodeal enclosure as in braccata; dorsolateral and posterior surface as in braccata but rugulae less evident; corbicular area with abundant small punctures in upper half or slightly more, surface moderately dulled by coarse reticular shagreening. Mesepisternum with small, shallow punctures separated mostly by two to three puncture widths, surface opaque, finely tessellate. Mesepisternum below impunctate, surface shiny, coarsely reticularly shagreened. Middle basitarsus not markedly expanded medially, with evenly curved sides, slightly narrower than hind basitarsus. Tibial spurs and claws normal. Front wing with venation as in helianthi.
Metasomal tergum 1 with apical area except narrow apical margin with distinct, round, deep, punctures separated by one to two puncture widths; basal area with similar punctures separated mostly by three to four puncture widths or more; surface dull, tessellate. Terga 2 and 3 similar but apical areas with punctures more crowded. Tergum 4 similar but basal area with punctures sparser. Tergum 5 with basal area with coarse punctures separated by one to four puncture widths. Pygidial plate V-shaped with narrow rounded apex. Sterna 2-5 with apical area impunctate, moderately shiny, extremely finely shagreened; basal areas with abundant punctures, near apical areas separated mostly by one to two puncture widths becoming sparser basally, surface dulled by tessellation.
VESTITURE. Generally pale ochraceous to ochraceous in color, vertex and dorsum of thorax dark ochraceous to yellowish, paler at sides and below. Tergum 1 without apical fascia. Terga 2-4 with apical fasciae of white hairs, that of tergum 2 generally narrowly interrupted medially. Terga 1-4 with basal areas with hairs sparse, short, pale, suberect. Terga 5 and 6 with long golden to white hairs. Sterna 2-5 with long pale ochraceous suberect hairs. Propodeal corbicula incomplete anteriorly, with abundant, long, plumose, internal hairs in upper half or more. Trochanteral flocculus complete, well developed. Tibial scopal hairs highly plumose throughout, of moderate length. Leg hairs pale ochraceous to ochraceous except inner surfaces tarsi golden-yellow.
MALE. MEASUREMENTS AND RATIOS. N = 20; length, 8-10 mm; width, 2.5-3.5 mm; wing length, 3.48 ą 0.175 mm; FL/FW, M = 0.98 ą 0.007; FS1/FS2, M = 2.09 ą 0.033.
INTEGUMENTAL COLOR. As in female except as follows: clypeus yellow except brown apical margin and small dark maculae below and mesad of tentorial pits; tegula usually rufescent; terga 1-5 narrowly hyaline apically.
STRUCTURE. Antennae in repose reach posterior margins of tegulae or slightly more; scape in length equals first 2 and 1/2 flagellar segments; flagellar segment 1 slightly shorter than segments 2 plus 3, segment 2 shorter than 3, segment 3 subequal to 4. Eye about three and one-half times as long as broad, inner margins converging slightly toward mandibles. Malar space, mandibles and galea as in female. Maxillary palpus as in female but segments in ratio oĢ about 1.1:1.0:1.0:0.7:0.6:0.8. Labial palpus as in female but segments in ratio of about 1.8:1.0:0.7:0.8. Labral process as in female but often shallowly emarginate medially. Clypeus and supraclypeal area as in female but clypeus with punctures slightly smaller and usually sparser, separated by half to one puncture width, usually without median impunctate area. Genal area, vertex and face above antennal fossae as in female but vertex usually shorter, above lateral ocellus equal to about one ocellar diameter and genal area subequal or slightly narrower than eye. Thorax sculptured as in female except as follows: mesoscutum usually evenly dulled by tessellation; lateral propodeal surface with scattered punctures in upper half, surface dull, tessellate. Wings, tibial spurs and claws as in female. Terga 1-5 as in terga 1-4 of female but punctures slightly more evident in basal areas. Tergum 6 as in female tergum 5. Sterna 2-5 with apical areas impunctate; basal areas with sparse distinct punctures separated by two to four puncture widths; surface dulled by coarse reticular shagreening. Sternum 6 shallowly emarginate apically, flat.
Genital capsule and sternum 8 (Figs 129-133) similar to those of helianthi. Note penis valve tips broad; gonoforceps with short hairs; sternum 8 much as in barberi.
VESTITURE. White to ochraceous, darker on vertex and dorsum of thorax than at sides and below. Tergum 1 with apical band of sparse long suberect hairs usually interrupted medially. Terga 2-5 with distinct apical pale fasciae. Terga 1-5 with basal vestiture sparse, pale, suberect, short. Terga 6 and 7 with long pale ochraceous to white hairs. Sterna 2-5 with long, sparse, ochraceous, suberect hairs, not forming distinct subapical bands. Leg hairs white to pale ochraceous except inner surfaces tarsi golden-yellow.
TYPE MATERIAL. Holotype female and allotype male (SECK), were collected by C. D. Michener and R. H. Beamer, at Yates Center, Kansas, September 7, 1949, on Amphiachyris dracuncutoides. Forty-five male and five female paratypes (USNM; CMP; INHS; SECK) are as follows: ILLINOIS: Carlinville, 1 female, Charles Robertson. KANSAS: Eureka: 1 female, September 7, 1949, C. D. Michener and R. H. Beamer, on Amphiachyris sp. Lawrence: 1 female, September 30, 1951, C. D. Michener, on Aster sp. Reece: 43 males, September 7, 1949, C. D. Michener and R. H. Beamer, on Amphiachyris dracunculoides. Riley County: September, Marlatt. NEBRASKA: Crawford (5 miles W.): 1 male, August 30, 1959, University of Nebraska State Museum Entomological Expedition, on Chrysothamnus sp. NEW MEXICO: Snow Hill (W. of): 1 female, October 6, 1895, on Aster sp. WYOMING: Gillette (12 miles E.): 1 male, August 29, 1962, 0. W. Isakson, on Chrysothamnus sp. A single female paratype of A. lincolnella Viereck and Cockerell in the U.S. National Museum, Washington, D.C., is also A. irrasus.
Andrena lincolnella: Viereck and Cockerell, 1914, Proceedings of the U.S. National Museum, vol. 48, p. 46 (misdetermination in part).
Updated: 2021-05-14 02:16:01 gmt