Lasioglossum crocoturum (Vachal 1904)

Lasioglossum crocoturum (Vachal)

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

Halictus sericeus Friese, 1916:304 [female]. [New synonymy.]

TYPE MATERIAL.—Vachal did not designate a holotype for Halictus crocoturus; his description was based on two females and one male. The one syntypic female available for study is herein designated the lectotype. It is labeled

Museum Paris, MEXIQUE, Coll. O. Sichel 1867/Mex[ico], [illegible word, presumably the collector name], [18]67 [handwritten]/HOLOTYPE [handwritten on red label]/crocoturus Vach[al] [handwritten]/Halictus crocoturus Vach.[al] [handwritten]/LECTOTYPE Halictus crocoturus Vachal des[ignated by] McGinley.

The lectotype is in good condition but has many hairs on the head and thorax matted, an old pin-hole on the left side of the propodeum and has evidence of old mold growth on the antennae. The lectotype, male paralectotypes and presumably the female paralectotype are deposited in the Paris Museum (MNHNP).

The female holotype of H. sericeus could not be located for study. See “Remarks” section for explanation of synonymy.

DISTRIBUTION (Figure 372).—Lasioglossum crocoturum is known from only 10 females and five males ranging from the Mexican states of Nayarit, Michoacan, and Oaxaca, south to Guatemala, EI Salvador, and Panama.

DIAGNOSIS.—Females and males of L. crocoturum can be distinguished from all other known Lasioglossum by the following combination: tergum IV nearly entirely covered by short, pale, adpressed pubescence (Figure 1; not the usual basal hair band) and the anterior edge of the forewing, including the marginal cell, conspicuously infuscated (Figure 1). Tergum III of L. crocoturum females is unique in having two transverse bands of pale, adpressed pubescence (Figure 1). Other characters helpful in recognizing L. crocoturum are the finely granuloso-punctate mesoscutum and the dense, conspicuous hair patches covering the pronotal lateral angle (Figure 1).

Other species having tergum IV covered by adpressed pubescence are L. tropidonotum and L. cercothrix. The former has a distinctive median longitudinal ridge on the mesoscutum (Figure 174) and lacks an infuscated wing pattern. Lasioglossum cercothrix has only the apex of the forewing infuscated (the marginal cell is hyaline). Furthermore, L. cercothrix has a coarsely punctate mesoscutum (Figure 313; finely granulosopunctate in L. crocoturum, Figure 1) and has a short head (Figure 310, length/width ratio 0.85–0.92; elongate in L. crocoturum, length/width ratio 0.88–0.96). Lasioglossum sandrae also has tergum IV covered by short, adpressed pubescence but is a much larger bee (body length 9.811.1, vs. 7.8–9.6) and has the mesoscutum conspicuously covered by short, suberect pubescence (mesoscutal hair elongate, erect in L. crocoturum).

DESCRIPTION.—FEMALE: (1) Length 7.8–9.6 mm (x = 7.5, n = 7); (2) wing length 2.4–2.7 mm (x = 2.6, n = 7); (3) abdominal width 2.4–3.0 mm (x = 2.8, n = 7).

Structure: (4) Head elongate; length/width ratio 0.88–0.96, x = 0.92, n = 7. (7) Supraclypeal area evenly rounded, (8) moderately protuberant. (9) Clypeus projecting approximately 0.82 of its length below lower margin of eyes; (11) surface without median longitudinal sulcation. (14) Distance between lateral ocelli slightly exceeded by distance between lateral ocellus and eye. (23) Flagellomere 1 subequal in length to 2 along dorsal surface. Labrum as in Figure 373; (27) distal keel moderately broad, short; (28) distal lateral projections very well developed, conspicuously broad, rounded; (29) fimbrial setae acutely pointed.

(32) Pronotal lateral angle broadly obtuse; (33) pronotal lateral ridge incomplete, narrowly interrupted by oblique lateral sulcus; (34) lower portion of lateral ridge narrowly rounded to sharply edged. (35) Mesoscutal lip weakly bilobed, (36) moderately elevated from pronotum. (40) Dorsal surface of propodeum about 0.65 the length of scutellum and about 1.1 times the length of metanotum, (41) slightly depressed centrally, (42) posterior margin broadly rounded; (43) propodeal triangle very weakly defined laterally, evident medially by low, rounded V-shaped elevation without lateral rims; (44) lateral carinae extending approximately three-fourths the length of the posterior surface, nearly reaching the dorsal propodeal surface. (45) Tibial spur as in Figure 29.

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

Sculpture: (47) Face moderately shiny, (48) densely and nearly uniformly punctate between ocelli and antennae, punctures contiguous and only slightly larger near antennae. (51) Supraclypeal area extremely granulate; (52) punctures separated by their width or less. (53) Clypeus granulate basally, apical half polished; (54) punctures separated by less than their width basally, less dense and larger on apical half. (56) Mesoscutum moderately shiny; (57) punctation as in Figure 1, punctures extremely dense, finely granuloso-punctate throughout. (58) Scutellum nearly uniformly granuloso-punctate, some punctures slightly separated near center. (63) Dorsal surface of propodeum (Figure 1) ruguloso-striolate; (64) surface alveolated. (65) Metasomal tergum I moderately shiny; (66) granulosopunctate throughout.

Coloration: (70) Posterior two-thirds of wing membrane mostly hyaline, anterior one-third along costal margin, including marginal cell, strongly infuscated.

Vestiture: (74) Pubescence of head golden (pale yellowish brown in specimens from Michoacan). (75) Pubescence of mesoscutum golden, hairs on pronotal lateral angle and metanotum yellowish white (specimens from Michoacan with mesoscutal hairs pale yellowish brown, pronotal and metanotal hairs white); hairs on pronotal lateral angle thick, conspicuous; (76) mesoscutal hairs moderately dense and plumose. (77) Hind tibial hair color differentiated, most hairs white, dorsal hairs light brown to brown. (78) Anterior hairs of metasomal tergum I white; (78) hair bands of terga II-IV yellowish white (white in specimens from Michoacan). (80) Acarinarium absent, elongate hairs scattered over anterior surface of tergum I. (80) Tergum III with two transverse, adpressed hair bands; tergum IV-V entirely covered by short, adpressed pubescence (Figure 1).

MALE: Similar to female except as follows: (1) length 7.2–8.5 mm (x = 8.0, n = 3); (2) wing length 2.1–2.3 mm (x = 2.2, n = 3); (3) abdominal width 1.9–2.0 (x = 2.0, n = 3). (4) Head elongate (length/width ratio 0.95–0.96, x = 0.96, n = 3). (5) Gena slightly wider than eye, (6) well produced posteriorly. (10) Clypeal surface flat, only faintly depressed near apical margin. Labrum as in Figure 374; (24) distal process absent; (25) basal area depressed medially; (26) basal lateral depressions faint to well developed. (30) Mandible short, just reaching opposing clypeal angle. (53) Clypeus weakly granulate basally, apical two-thirds polished; (54) punctures well formed, nearly contiguous basally, very fine and scattered over apical two-thirds. (68) Clypeal maculation present. (69) Flagellum entirely dark. (72) Tarsi dark, concolorous with tibiae.

Vestiture: Sternal vestiture as in Figure 375; (82) hairs on sternum IV moderately short and suberect to erect medially, becoming noticeably longer and erect laterally; (83) sternum V without conspicuous erect hairs, posterior edge of sternum with broadly rounded, adpressed hair lobes.

Terminalia: Sterna VII–VIII as in Figure 380; (85) sternum VIII with short, broad, apically rounded median process. Genitalia as in Figures 376–379; (86) gonobase moderately elongate; (87) gonostylus broad basally, tapering to narrowly rounded apex; (89) retrorse membranous lobe enormously broad; (90) volsella with prominent lateral lobe.

FLIGHT RECORDS.—Females of L. crocoturum have been collected in February, March, late May, and late September. All known male records are from March.

Lasioglossum crocoturum là một loài Hymenoptera trong họ Halictidae. Loài này được Vachal mô tả khoa học năm 1904.