Lasioglossum tropidonotum McGinley 1986

Lasioglossum tropidonotum

TYPE MATERIAL.—The female holotype is the property of the California Insect Survey, University of California, Berkeley, but is on loan deposit to the California Academy of Sciencies in San Francisco. The specimen is in excellent condition and is labeled

4 mi NW Ocosingo Chiapas, MEX. III [Mar]-8-1953/R.C. Bechtel E.I. Schlinger Collectors/[green unlabeled paper point]/LASIOGLOSSUM ? det. G.C. Eickwort/HOLO-TYPE Lasioglossum tropidonotum R.J. McGinley [red label].

The male paratype listed in the “Specimens Examined” section is deposited in the collection of the University of California at Berkeley.

ETYMOLOGY.—The specific epithet is derived from the Latin tropidos (keel) and alludes to the distinctive, mesoscutal ridge that is unique to this species.

DISTRIBUTION (Figure 300).—Lasioglossum tropidonotum is known only from the female holotype and male paratype, both from the vicinity of Ocosingo in the state of Chiapas, Mexico.

DIAGNOSIS.—Both sexes of L. tropidonotum have a unique, median mesoscutal ridge near the anterior mesocutal margin (Figure 174). The female is also unique in having an extremely protuberant clypeus and having the frons and vertex covered with thick, distally recurved setae (Figures 174, 723). Furthermore, the female has sterna IV-V entirely covered by short, pale pubescence (found elsewhere only in L. crocoturum and L. cercothrix).

DESCRIPTION.—FEMALE: (1) Length 10.3 mm (n = 1); (2) wing length 2.6 mm; (3) abdominal width 3.0 mm.

Structure: (4) Head elongate (Figure 174; length/width ratio 0.96). (7) Supraclypeal area narrowly rounded ventrally, (8) protuberant. (9) Clypeus projecting approximately 0.76 of its length below lower margin of eyes; (10) surface without median longitudinal sulcation. (14) Distance between lateral ocelli subequal to distance between lateral ocellus and eye. (23) Flagellomere 1 subequal to 2 along dorsal surface. Labrum virtually identical to that of L. circinatum, Figure 333; (27) distal keel moderately broad, widest basally; (29) distal lateral projections virtually absent, evident as obscure swellings; (29) most fimbrial setae blunt apically.

(32) Pronotal lateral angle narrowly obtuse; (33) pronotal lateral ridge incomplete, interrupted by oblique lateral sulcus; (34) lower portion of lateral ridge narrowly rounded. (34) Mesoscutal lip not bilobed, (35) very weakly elevated from pronotum; unlike all other known Lasioglossum, the mesoscutum is elevated as a median longitudinal ridge near the anterior margin. (39) Dorsal surface of propodeum about 0.83 the length of scutellum and about 1.2 times the length of metanotum, (40) slightly depressed centrally, (41) posterior margin broadly rounded; (42) propodeal triangle weakly defined, evident medially as a very low V-shaped elevation without lateral rims; (43) lateral carinae extending at most to midpoint of posterior surface. (44) Tibial spur as in Figure 58.

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

Sculpture: (47) Face weakly shiny, (48) densely and contiguously punctate below ocelli to antennae. (51) Supraclypeal area granulate, roughened ventrally; (52) punctures separated by their width. (53) Clypeus moderately granulate throughout; (54) punctures very dense, nearly contiguous over basal half, being larger and obscurely formed apically. (56) Mesoscutum moderately shiny; (57) punctation very similar to that of L. circinatum, Figure 335, obscurely doubly-punctate, smaller punctures extremely dense, contiguous throughout, larger punctures 3–5 times their width apart (observable at 50 magnifications or more). (58) Scutellum contiguously punctate around margins, sparsely punctate centrally, punctures separated by 1–2 time their width. (63) Dorsal surface of propodeum (similar to Figure 334) nearly entirely smooth, weakly striolate laterally with very weak median striae confined to basal one-third; (64) surface extensively alveolated. (65) Metasomal tergum I shiny; (66) punctation fine, dense over most of dorsal surface, punctures slightly less than their width apart, becoming very sparse near and on anterior surface.

Coloration: (71) Wing membrane very weakly infuscated throughout.

Vestiture: (73) Unlike other species, vertex and frons covered with thick, recurved setae (simple recurved hairs are found in L. acarophilum, L. circinatum, L. pharum, and L. uyacicola but are not thick and pigmented as in L. tropidonotum); (74) pubescence of head mostly white, thickened setae on vertex and frons orange-brown. (75) Pubescence of thorax white; (76) mesoscutal hairs inconspicuous. (77) Hind tibial hair color differentiated, ventral and lateral hairs white, dorsal hairs brown. (78) Anterior hairs of metasomal tergum I white; (79) basal hair bands of terga II–III yellowish white, terga IV–V nearly entirely covered by yellowish, short pubescence. (80) Acarinarium absent, elongate hairs scattered over anterior surface of tergum I.

MALE: Similar to female except as follows: (1) length 7.5 mm (n = 1); (2) wing length 2.2 mm; (3) abdominal width 1.8 mm. (4) Head as in Figure 722 (length/width ratio 0.96). (5) Gena subequal to eye in width, (6) moderately produced posteriorly. (10) Clypeal surface noticeably depressed ventrally. Labrum similar to that of L. asaphes (Figure 277); (24) distal process absent; (25) basal area strongly depressed medially; (26) basal lateral depressions well developed. (30) Mandible moderately elongate, reaching just beyond opposing clypeal angle. (53) Clypeus polished; (54) punctures well formed and dense basally, very fine and scattered over apical two-thirds becoming virtually impunctate medially near apical edge. (68) Clypeal maculation present. (69) Flagellum nearly entirely dark, only slightly paler ventrally than on dorsum. (72) Tarsi dark, concolorous with tibiae.

Vestiture: (82) Hairs on sternum IV erect, elongate, hairs becoming slightly longer laterally; (83) sternum V with median rosette of short erect hairs, becoming elongate and curled laterally.

Terminalia: Sterna VII–VIII virtually identical to those of L. acarophilum, Figure 256; (85) sternum VIII with sharply pointed median process. Genitalia as in Figures 719–721; (86) gonobase elongate; (87) gonostylus moderately elongate, sharply pointed; (89) retrorse membranous lobe tapering distally to acute apex; (90) volsella lacking prominent lateral lobe.

FLIGHT RECORDS.—Both known specimens of Lasioglossum tropidonotum were collected in March.