Lasioglossum cercothrix McGinley 1986

Lasioglossum cercothrix

TYPE MATERIAL.—The female holotype of L. cercothrix, in the University of California, Davis, is labeled

Mex[ico] 4 mi SE Temoris Chih[uahua] VIII [Aug] 29 1969/ T A Sears R O Gardner C S Glaser/HOLOTYPE Lasioglossum cercothrix R.J. McGinley [red label].

The holotype is in excellent condition. Eight paratypes, including the one known male, are in the University of California, Davis; six at Utah State University, Logan; three at the University of Kansas, Lawrence; and one at Oregon State University, Corvallis.

ETYMOLOGY.—The specific epithet is derived from the Greek kerkos (tail) plus thrix (hair), a reference to the terminal terga of this species being entirely covered by dense, adpressed pubescence.

DISTRIBUTION (Figure 309).—Lasioglossum cercothrix is presently known from only 19 females and one male. It appears to be a widespread species in Mexico, with current records ranging from Chihuahua south to the state of Puebla.

DIAGNOSIS.—The coarse, contiguous mesoscutal punctation (Figure 313) and the presence of short, adpressed hairs entirely covering terga IV–V (females; similar to Figure 1) and terga IV–VI (males) will distinguish L. cercothrix from all other known New World Lasioglossum. Lasioglossum sandrae, L. crocoturum, and L. tropidonotum are the only other Lasioglossum species having the terminal terga entirely covered by short, adpressed hairs. The latter two species differ from L. cercothrix in having much finer mesoscutal punctuation that is granuloso-punctate throughout (Figure 1) and in having longer heads (Figure 723; L. cercothrix head short, Figure 310). Lasioglossum sandrae is a very different bee, having the mesoscutum entirely covered by short, adpressed pale hairs. Also helpful in recognizing L. cercothrix is the rounded, relatively smooth and shiny posterior edge of the propodeal dorsal surface (Figure 312).

DESCRIPTION.—FEMALE: (1) Length 8.3–9.8 mm (x = 8.9, n = 15); (2) wing length 2.4–3.0 mm (x = 2.8, n = 15); (3) abdominal width 2.73.0 (x = 2.9, n = 15).

Structure: (4) Head short (Figure 310; length/width ratio 0.85–0.92, x = 0.88, n = 15). (7) Supraclypeal area evenly rounded, (8) moderately protuberant. (9) Clypeus projecting approximately 0.69 of its length below lower margin of eyes; (11) surface with 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. Labrum as in Figure 311; (27) distal keel moderately broad, lateral edges bowed, with conspicuous basal groove; (28) distal lateral projections moderately well developed, triangular; (29) fimbrial setae acutely pointed.

(32) Pronotal lateral angle narrowly obtuse; (33) pronotal lateral ridge incomplete, interrupted by oblique lateral sulcus; (34) lower portion of lateral ridge weakly edged near oblique sulcus, becoming broadly rounded ventrally. (35) Mesoscutal lip very weakly bilobed, (36) moderately elevated from pronotum. (40) Dorsal surface of propodeum about 0.78 the length of scutellum and about 1.4 times the length of metanotum, (41) slightly depressed centrally, (42) posterior margin broadly rounded; (43) propodeal triangle very weakly defined, evident medially as an extremely inconspicuous V-shaped elevation (margin of dorsal surface unusually rounded with no indications of lateral rims); (44) lateral carinae extending approximately two-thirds the length of posterior surface. (45) Tibial spur as in Figure 23.

(46) Lateral edge of metasomal tergum II straight, broadly rounded posteriorly.

Sculpture: (47) Face moderately shiny, (48) densely punctate below ocelli, punctures contiguous, becoming only slightly larger and less dense near antennae. (51) Supraclypeal area strigulate; (52) punctures separated by their width or less laterally, becoming sparse centrally. (53) Clypeus obscurely granulate basally, apical two-thirds polished; (54) punctures separated by less than their width, apicolateral areas very sparsely punctate. (56) Mesoscutum moderately dull; (57) punctation as in Figure 313, punctures coarse, dense and nearly contiguous throughout, interspaces granulate. (58) Scutellum nearly uniformly punctate, punctures at most separated by their width. (63) Dorsal surface of propodeum (Figure 312) striolate laterally, becoming finely ruguloso-striolate medially, posterior edge rounded, somewhat smooth with scattered obscure rugulae; (64) surface not noticeably alveolated. (65) Metasomal tergum I moderately shiny; (66) punctation fine, extremely dense posteriorly, nearly granuloso-punctate, less dense anteriorly, punctures separated by their width or slightly less.

Coloration: (71) Wing membrane mostly hyaline, lightly infuscated at apex.

Vestiture: (74) Pubescence of head white on gena and near antennae, becoming golden near ocelli and on vertex. (75) Pubescence of thorax mostly white, hairs on mesoscutum and scutellum yellowish brown; (76) mesoscutal hairs moderately dense, simple. (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. (81) Unlike most other species, basal hair band on tergum II absent, hair band on tergum IV covers entire tergal surface.

MALE: Similar to female except as follows: (1) length 8.2 mm (n = 1); (2) wing length 2.4 mm; (3) abdominal width 2.2 mm. (4) Head short (length/width ratio 0.88). (5) Gena narrower than eye, (6) moderately produced posteriorly. (10) Clypeal surface flat. (24) Labral distal process absent; (25) basal area depressed medially; (26) basal lateral depressions small but distinct. (30) Mandible short, just reaching opposing clypeal angle. (53) Clypeus weakly granulate throughout, shiny; (54) punctures well formed, nearly contiguous basally, less dense over apical two-thirds. (68) Clypeal maculation present. (69) Flagellum entirely dark. (72) Tarsi dark, concolorous with tibiae.

Vestiture: Sternal vestiture as in Figure 318; (82) hairs on sternum IV moderately elongate, suberect, posterior sternal edge with noticeable fringe of pale hairs; (83) posterior edge of sternum V with conspicuous hair fringe, only indistinctly divided medially into lateral lobes.

Terminalia: Sterna VII–VIII as in Figure 314; (85) sternum VIII with moderately short, narrowly rounded median process. Genitalia as in Figures 315–317; (86) gonobase moderately elongate; (87) gonostylus elongate, slender (unlike other species, gonocoxite hairy distally near base of gonostylus; (89) retrorse membranous lobe broad near midpoint, tapering apically; (90) volsella with prominent lateral lobe.

FLIGHT RECORDS.—Female records range from late June to late September. The one known male was collected in late August.

FLOWER RECORDS.—Two pollen-laden females taken from Xanthoxylum (Rutaceae) in the state of Puebla (8 mi SE Tehuitzingo).

SPECIMENS EXAMINED.—20(19, 1).

MEXICO. CHIHUAHUA: Santo Nino, 31 Aug 1968, T.A. Sears, R.C. Gardner, C.S. Glaser (2 UCD), 1 Sep 1968, T.A. Sears, R.C. Gardner, C.S. Glaser (3 UCD); Temoris, 3 Sep 1969, T.A. Sears, R.C. Gardner, C.S. Glaser (1 UCD), 2 mi N, 22 Aug 1968, T.A. Sears, R.C. Gardner, C.S. Glaser (1 UCD), 3 mi SE, 8 Sep 1969, Sears, Gardner, Glaser (1 UCD), 4 mi SE, 29 Aug 1969, Sears, Gardner, Glaser (1 holotype, 1 UCD). JALISCO: Guadalajara, 15 mi NE, 17 Sep 1970, G.E. & R.M. Bohart (6 USU). MICHOACAN: Tuxpan to San Jose Purva, 22 Jun 1963, 5200 ft, Scullen & Bolinger (1; OrS). PUEBLA: Petlalcingo, 4 mi NW, 4 Jul 1953, Univ. Kansas Mex. Exped. (1; KU); Tehuitzingo, 8 mi SE. 29 Jun 1961, 4100 ft, Univ. Kansas Mex. Exped. (2; KU).