Lasioglossum aequatum (Vachal 1904)

Lasioglossum aequatum (Vachal)

Halictus aequatus Vachal, 1904:473 [female],—Cockerell, 1905a:90 [key].

Lasioglossum aequatum.—Moure and Hurd, 1986:59 [catalog].

TYPE MATERIAL.—The female holotype is in the Naturhistorisches Museum, Vienna. At some time, the head and front legs were broken off and crudely glued back to the thorax, the vertex being attached to the pronotum and mesoscutum. The left front leg is missing and the metasomal basal hair bands are matted and dark. The specimen is labeled

Forrer./Mexico Mazatl[an] 1883. III [March] Farrer./aequatus Vach.[al] det. J. Vachal/Hal.[ictus] aequatus Vach.[al] [handwritten]/LASIOGLOSSUM Lasioglossum aequatum (Vachal, 1904) Holotypus des. A.W. Ebmer 1980 [right edge with red border].

DISTRIBUTION (Figure 258).—Only three female specimens of this Mexican species are known: the holotype from Mazatlan, one specimen from near Mexico City, and another from El Chico, Hidalgo.

DIAGNOSIS.—Lasioglossum aequatum is unique in having the dorsal propodeal surface strongly and regularly striate, the striae being fine and reaching the posterior propodeal margin (Figure 259). Other helpful characters are as follows: head short (similar to Figure 303); mesoscutum coarsely granuloso-punctate (similar to Figure 336 but punctures not so large); acarinarium absent; forewing membrane hyaline with infuscated apex. Lasioglossum costale is similar but in addition to differing in propodeal sculpture has pale orange wing membranes and less coarse mesocutal punctation. Lasioglossum crocoturum and L. cercothrix have metasomal terga IV–V entirely covered by short, adpressed pubescence (Figure 1). Lasioglossum tricnicos is superficially similar but has the anterior costal edge of the forewing conspicuously infuscated.

DESCRIPTION.—FEMALE: (1) Length 7.9–8.9 mm (x = 8.3, n = 3); (2) wing length 2.2–2.4 mm (x = 2.3, n = 3); (3) abdominal width 2.5–2.6 mm (x = 2.5).

Structure: (4) Head short (similar to Figure 303; length/width ratio 0.83–0.92, x = 0.88, n = 3). (7) Supraclypeal area evenly rounded, (8) weakly protuberant. (9) Clypeus projecting approximately 0.78 of its length below lower margin of eyes; (11) surface with weakly developed median longitudinal sulcation. (14) Distance between lateral ocelli subequal to distance between lateral ocellus and eye. (23) Flagellomere 1 subequal to 2 in length along dorsal surface. (27) Labral distal keel broad in frontal view, spoon-shaped with conspicuous basal, median groove; (28) distal lateral projections absent; (29) fimbrial setae acutely pointed.

(32) Pronotal lateral angle narrowly obtuse, sharply pointed; (33) pronotal lateral ridge incomplete, interrupted by oblique lateral sulcus; (34) lower portion of lateral ridge narrowly rounded. (35) Mesoscutal lip weakly bilobed, (36) moderately elevated from pronotum. (40) Dorsal surface of propodeum about 0.74 the length of scutellum and about 1.3 times the length of metanotum, (41) slightly depressed centrally, (42) posterior margin very broadly rounded; (43) propodeal triangle weakly defined, median V-shaped elevation inconspicuous; (44) lateral carinae extending to dorsal surface, becoming weakly defined along dorsal edge. (45) Tibial spur as in Figure 16.

(46) Lateral edge of metasomal tergum II weakly sinuate.

Sculpture: (47) Face shiny, (48) densely and uniformly punctate between ocelli and antennae, punctures contiguous. (51) Supraclypeal area extremely granulate; (52) punctation sparse and scattered. (53) Clypeus granulate throughout; (54) punctures separated by their width or less basally, slightly less dense apically. (56) Mesoscutum moderately shiny; (57) punctures coarse, contiguous to nearly contiguous throughout, interspaces granulate, becoming obscurely scabrous anteriorly. (58) Scutellum densely punctate throughout, punctures adjacent to median line coarse, similar to those of mesoscutum. (63) Dorsal surface of propodeum (Figure 259) strongly and regularly striate, striae reaching posterior margin; (64) surface not noticeably alveolated. (65) Metasomal tergum I moderately shiny; (66) surface granuloso-punctate.

Coloration: (71) Wing membrane mostly hyaline, marginal cell and apex infuscated.

Vestiture: (74) Pubescence of head pale yellowish brown. (75) Pubescence of thorax pale yellowish brown; (76) mesoscutal hairs moderately dense and plumose. (77) Hind tibial hair color differentiated, most hairs white, dorsal hairs light to dark brown. (78) Anterior hairs of metasomal tergum I white, (79) basal hair bands of terga II–IV yellowish white. (80) Acarinarium absent, elongate hairs scattered over anterior surface of tergum I.

SPECIMENS EXAMINED.—3.

MEXICO. HIDALGO: El Chico, 23 Sep 1938, L.J. Lipovsky (1; KU). MEXICO: Mexico City, 38 mi SE, 26 Apr 1965, 9000–9500 ft, on Senecio sylvaticus, H.V. Weems, Jr. (1; FSCA). SINALOA: Mazatlan, Mar 1883 (1; NMW).