Lasioglossum costale (Vachal 1904)

Lasioglossum costale (Vachal)

Halictus costalis Vachal, 1904:475 [female].—Cockerell, 1905a:90 [key].

Halictus matensis Friese, 1916:303 [female]. [New Synonymy.]

Lasioglossum costale.—Moure and Hurd, 1986:60 [catalog].

TYPE MATERIAL.—Vachal based his description of Halictus costalis on four syntypic females deposited in the Paris Museum (MNHNP). Moure and Hurd (1986) state that “one of the females of the original type series (collection Sichel) was labeled by one of us (Moure) in April, 1958 as the lectoholotype and is now so designated.” This specimen now lacks the lectoholotype label mentioned above and instead has a large red “HOLOTYPE” label. In order to avoid additional confusion I have reattached a lectotype label with the designation attributed to Moure. The lectotype is in good condition, missing only the last two tarsomeres of the left hind leg and most of the mesoscutal hairs. It is labeled

MUSEUM PARIS Mexique [handwritten] COLL. O. SICHEL 1867/HOLOTYPE [handwritten on red label]/ costalis Vach.[al] [handwritten by Vachal?]/Halictus costalis Vach. [handwritten]/LECTOTYPE Halictus costalis Vachal des.[ignated by] Moure [red label; labeled by McGinley, 1984].

I have attached yellow “PARALECTOTYPE” labels to the three remaining females in Vachal's original series.

Friese based his description of H. matensis on two females from San Mateo, Costa Rica. The one specimen available for study is herein designated the lectotype; it is labeled

Costa Rica San Mateo 1904/Halictus matensis 1915 Friese Fr. det./Typus [square orange label]/Zool. Mus. Berlin/ LECTOTYPE Halictus matensis des.[ignated by] McGinley.

The lectotype is missing the left antenna but otherwise is in excellent condition. It is deposited in the Museum für Naturkunde der Humboldt-Universität zu Berlin.

DISTRIBUTION (Figure 365).—Lasioglossum costale has been collected from Costa Rica, Guatemala, Honduras, and the Mexican states of Michoacan, Veracruz, and Chiapas. Only 22 females and 6 males are currently known.

DIAGNOSIS.—The combination of the entirely granuloso-punctate mesoscutum (similar to Figure 649; not coarse as in L. cercothrix, Figure 313), ruguloso-striolate dorsal propodeal surface (as in Figure 1), the absence of a metasomal acarinarium and the lack of conspicuous infuscation along the anterior edge of the forewing will distinguish the females of L. transvorsum, L. costale, L. manitouellum, L. asaphes, and L. xyriotropis from those of other New World Lasioglossum. Lasioglossum transvorsum is easily recognized by the elevated, V-shaped propodeal rim (Figure 650) and the distinctive, adpressed hair patches on the anterior surface of tergum I (Figure 651). The pronotal lateral carina of L. asaphes and L. xyriotropis is complete (Figures 280, 732), whereas that of L. costale and L. manitouellum is distinctly interrupted by a lateral sulcus. This interruption is broad and conspicuous in L. costale (Figure 281) versus narrow yet distinct in L. manitouellum. The latter species has hyaline forewing membranes with lightly infuscated apices (Figure 152), whereas the wings of L. costale are pale orange throughout.

Most females of L. costale have pale yellowish brown mesoscutal pubescence and distinctive pale yellowish orange hind tibiae. However, three females, including both types, have dark brown mesoscutal hairs and dark brown tibiae (see “Remarks” section).

The males of L. costale can be recognized by the vestiture of sternum V, which is characterized by a dense rosette of short hairs on the posterior edge that expands into lateral lobes of relatively long hairs (Figure 371).

DESCRIPTION.—FEMALE: (1) Length 7.8–9.3 mm (x = 8.6, n = 13); (2) wing length 2.3–2.6 mm (x = 2.5, n = 13); (3) abdominal width 2.3–2.9 mm (x = 2.7, n = 13).

Structure: (4) Head short (similar to Figure 303); length/width ratio 0.83–0.92, x = 0.89, n = 13. (7) Supraclypeal area slightly narrowly rounded, (8) moderately protuberant. (9) Clypeus projecting approximately 0.85 of its length below lower margin of eyes; (11) surface apparently without 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 366; (27) distal keel moderately narrow in frontal view, nearly parallel-sided; (28) distal lateral projections somewhat small but distinct, triangular; (29) fimbrial setae acutely pointed.

(32) Pronotal lateral angle narrowly obtuse, 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 0.84 the length of scutellum and about 1.6 times the length of metanotum, (41) depressed centrally, (42) posterior margin broadly rounded; (43) propodeal triangle weakly defined, evident medially as a low V-shaped elevation, lateral rims absent; (44) lateral carinae extending approximately one-third the length of posterior surface. (45) Tibial spur as in Figure 28.

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

Sculpture: (47) Face shiny, (48) densely and uniformly punctate between ocelli and antennae, punctures contiguous. (51) Supraclypeal area strigulate; (52) obscurely and sparsely punctate, punctures separated by 1–5 times their width. (53) Clypeus granulate basally, apical two-thirds moderately polished; (54) punctures obscure basally, large and elongated apically, separated by their width or less. (56) Mesoscutum moderately shiny; (57) punctation as in Figure 649, punctures extremely dense, contiguous throughout, becoming granuloso-punctate anteriorly. (58) Scutellum granuloso-punctate posteriorly, punctures less dense and larger anteriorly adjacent to median line, separated by 1–2 times their width. (63) Dorsal surface of propodeum completely ruguloso-striolate (similar to Figure 1); (64) surface alveolated. (65) Metasomal tergum I moderately shiny; (66) punctation fine, extremely dense, punctures nearly contiguous.

Coloration: (71) Wing membrane deep yellowish orange, becoming infuscated apically.

Vestiture: (74) Pubescence of head yellowish brown near antennae, becoming gold-brown on vertex (brown on vertex in three females). (75) Pubescence of thorax mostly pale yellowish brown, white on pronotal lateral angle and pronotal lobe (mesoscutal hairs brown in three females); (76) mesoscutal hairs moderately dense and plumose. (77) Hind tibial hair color differentiated, ventral hairs golden, dorsal hairs brown (hairs mostly dark brown in three females). (78) Anterior hairs of metasomal tergum I pale yellowish brown, (79) basal hair bands of terga II–IV white. (80) Acarinarium absent, elongate hairs scattered over anterior surface of tergum I.

MALE: Similar to female except as follows: (1) length 6.4–8.0 mm (x = 7.2, n = 3); (2) wing length 2.0–2.2 mm (x = 2.1, n = 3); (3) abdominal width 1.8–2.1 mm (x = 2.0, n = 3). (4) Head moderately elongate (length/width ratio 0.91–0.95, x = 0.92, n = 3). (5) Gena subequal to eye in width, (6) moderately produced posteriorly. (10) Clypeal surface shallowly depressed ventrally. (24) Labral distal process absent; (25) basal area depressed medially; (26) basal lateral depressions weakly developed. (30) Mandible short, just reaching opposing clypeal angle. (53) Clypeus 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 371; (82) hairs on sternum IV moderately short, suberect to erect; (83) hairs on sternum V very short, suberect, posterior edge of sternum with median rosette of short, dense hairs that expand laterally into moderately elongate hair lobes.

Terminalia: Sterna VII—VIII as in Figure 367; (85) sternum VIII with short, broadly rounded median process. Genitalia as in Figures 368–370; (86) gonobase moderately elongate; (87) gonostylus extremely elongate and slender; (89) retrorse membranous lobe moderately broad with characteristic hair patch along apical margin; (90) volsella with prominent lateral lobe.

FLIGHT RECORDS.—Lasioglossum costale females have been collected in every month except January, August, and November. The six known males have been taken from early March through May.

FLOWER RECORDS.—One pollen-laden female taken from Bidens pilosa (Compositae) in Michoacan, Mexico.