Lasioglossum tricnicos (Vachal 1904)

Lasioglossum tricnicos (Vachal)

Halictus tricnicos Vachal, 1904:474 [female].—Cockerell, 1905a:90 [key].

Lasioglossum tricnicos.—Moure and Hurd, 1986:66 [catalog].

TYPE MATERIAL.—The female holotype is labeled

Museum Paris Mexique coll. O. Sichel 1867/Sierra [illegible letter] Rivas [handwritten]/Mex[ico] [18]63 [illegible word, presumably the collector name] [handwritten]/Holotype [handwritten on red label]/tricnicos Vach[al] [handwritten] /Halictus tricnicos Vach.[al] [handwritten].

The specimen has an old pin-hole in the left pleuron but otherwise is in excellent condition. It is housed in the Paris Museum (MNHNP).

DISTRIBUTION (Figure 659).—Lasioglossum tricnicos is presently known from only five females and three males, which were collected in five south-central Mexican states: Distrito Federal, Mexico, Michoacan, Morelos and Tlaxcala. Two specimens were collected at elevations of 8500 and 9600 feet.

DIAGNOSIS.—Lasioglossum tricnicos can be recognized by the following character combination: posterior two-thirds of wing membrane hyaline, anterior third along costal margin heavily infuscated (as in Figure 177); mesoscutum very finely and completely granuloso-punctate (as in Figure 1); pronotal lateral angles densely covered with conspicuous white pubescence. The above characters will distinguish L. tricnicos from all other New World Lasioglossum except L. crocoturum, which is easily differentiated by having the metasomal terga IV–V nearly entirely covered by short, dense, adpressed hairs (Figure 1) and by having a relatively longer head than that of L. tricnicos. Other Lasioglossum having the anterior third of the wing membrane infuscated along the costal margin are L. eickworti, L. sandrae, and L. katyae, but these are conspicuously larger bees than L. tricnicos (body length 9.5–11.9 mm versus 8.4–9.0 mm) and generally occur south of the known distribution of L. tricnicos (Figure 395; only L. sandrae is known to be potentially sympatric with L. tricnicos and can be recognized by the conspicuous mat of short hairs covering the mesoscutum).

The infuscated anterior edge of the forewing and the erect, lateral hair tufts on sternum V (Figure 662) will distinguish the males of L. tricnicos from those of all other known Lasioglossum.

DESCRIPTION.—FEMALE: (1) Length 8.4–9.0 mm (x = 8.7, n = 3); (2) wing length 2.5–2.6 mm (x = 2.5, n = 3); (3) abdominal width 2.5 mm (x = 2.5, n = 3).

Structure: (4) Head short (similar to Figure 545; length/width ratio 0.87–0.89, x = 0.88, n = 3). (7) Supraclypeal area evenly rounded, (8) very weakly protuberant. (9) Clypeus projecting approximately 0.73 of its length below lower margin of eyes; (11) surface without median longitudinal sulcation. (13) Distance between lateral ocelli slightly exceeded by distance between lateral ocellus and eye. (23) Flagellomere 1 subequal to 2 in length along dorsal surface. Labrum as in Figure 660; (27) distal keel moderately broad in frontal view, lateral edges bowed; (28) distal lateral projections weakly developed, 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 moderately edged. (35) Mesoscutal lip very weakly bilobed, (36) moderately elevated from pronotum. (40) Dorsal surface of propodeum about 0.75 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 laterally, evident medially by low, rounded V-shaped elevation without lateral rims; (44) lateral carinae extending approximately two-thirds the length of posterior surface. (45) Tibal spur as in Figure 56.

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

Sculpture: (47) Face moderately shiny, (48) densely and uniformly punctate between ocelli and antennae, punctures contiguous. (51) Supraclypeal area extremely granulate; (52) uniformly and densely punctate, punctures separated by their width or less. (53) Clypeus granulate basally, apical two-thirds polished; (54) punctures separated by less than their width basally, less dense apically. (56) Mesoscutum moderately shiny; (57) punctation as in Figure 1, punctures extremely dense, granuloso-punctate throughout. (58) Scutellum uniformly granuloso-punctate. (63) Dorsal surface of propodeum weakly ruguloso-striolate laterally, striae becoming very obscure medially, almost ruguloso-granulate; (64) surface alveolated. (65) Metasomal tergum I moderately shiny; (66) granuloso-punctate throughout.

Coloration: (71) Posterior two-thirds of wing membrane mostly hyaline, anterior one-third along costal margin deeply infuscated.

Vestiture: (74) Pubescence of head white to very light brown near antennae, becoming brown on vertex. (75) Pubescence of thorax white on pronotal lateral angle, pronotal lobes, metanotum and propodeum; 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 brown to dark brown. (78) Anterior hairs of metasomal tergum I white, (79) basal hair bands of terga II–IV white to yellowish white. (80) Acarinarium absent, elongate hairs scattered over anterior surface of tergum I.

MALE: Similar to female except as follows: (1) length 7.8–8.1 mm (x = 8.0, n = 3); (2) wing length 2.1–2.2 mm (x = 2.1, n = 3); (3) abdominal width 1.8–2.0 mm (x = 1.9, n = 3). (4) Head short (length/width ratio 0.90–1.0, x = 0.95, n = 3). (5) Gena subequal to eye in width, (6) moderately produced posteriorly. (10) Clypeal surface broadly rounded, only faintly depressed along ventral edge. Labrum as in Figure 661; (24) distal process absent; (25) basal area depressed medially; (26) basal lateral depressions conspicuously developed. (30) Mandible short, just reaching opposing clypeal angle. (53) Clypeus granulate basally, apical two-thirds polished; (54) punctures well formed, nearly contiguous basally, apical two-thirds with scattered, moderately large punctures. (68) Clypeal maculation present. (69) Flagellum brown ventrally, slightly paler than dark dorsum. (72) Tarsi dark, concolorous with tibiae.

Vestiture: Sternal vestiture as in Figure 662; (82, 83) hairs on sterna IV and V short, suberect medially, becoming longer and erect laterally, forming noticeable elongate hair tufts.

Terminalia: Sterna VII–VIII as in Figure 667; (85) sternum VIII with moderately broad, apically truncate, semicircular median process. Genitalia as in Figures 663–666; (86) gonobase elongate; (87) gonostylus elongate, slender; (89) retrorse membranous lobe moderately broad; (90) volsella with prominent lateral lobes.

FLIGHT RECORDS.—One of the five known females of L. tricnicos was collected in June; the other female with flight data was collected in October. The three males were collected in June, July, and December.

FLOWER RECORDS.—One female taken from Stylosanthes (Leguminosae) in the state of Tlaxcala.

ADDITIONAL SPECIMENS EXAMINED.—7 (4, 3).

MEXICO. DISTRITO FEDERAL: Mexico City, 50 km E, 29 Dec 1949, L.D. Beamer (1; KU). MEXICO: El Oro City, summer 1924, P.W. Ayers (1; USNM); Toluca, 15.5 mi E, 6 Jul 1961, 9600 ft, Univ. Kansas Mex. Exped. (1; KU). MICHOACAN: Morelia (1; UCR). MORELOS: Cuernavaca, 22 Oct 1922, E.G. Smyth (1; USNM), 9 mi N, 27 Jun 1959, 8500 ft, H.E. & M.A. Evans (1; CU). TLAXCALA: Apizaco, 8 mi WNW, 18 Jun 1961, Univ. Kansas Mex. Exped. (1; KU).

THE trizonatum GROUP

SPECIES INCLUDED.—Lasioglossum anhypops, new species; L. egregium (Vachal); L. mellipes (Crawford); L. trizonatum (Cresson).

DISTRIBUTION (Figure 668).—The trizonatum group is very common throughout much of the western United States and southern Canada. The group ranges from Moresby Island off the coast of British Columbia, south to southern California, Arizona, and New Mexico. The species do not occur east of the 100th meridian, reaching central Colorado and the western edge of the Dakotas.

DIAGNOSIS.—Females of this group are rather nondescript and have commonly been confused with a variety of other Lasioglossum species. They are moderately large (body length x = 8.2–9.7 mm) with elongate heads (Figures 670, 683, 697, 709; length/width ratio 0.93–1.02). The posterior margin of the dorsal propodeal surface is rounded (Figure 113; not broadly rounded, Figure 110; or truncate, Figure 127, as in most other species). The dorsal propodeal surface is noticeably elongate and ruguloso-striolate. Lasioglossum colatum has a similar propodeal surface but has a shorter head (Figure 339, length/ width ratio 0.91) and distinctive short, adpressed hairs on the anterior surface of tergum I (Figure 351). The posterior margin of the dorsal propodeal surface is rounded and lacks the slightly elevated lateral rims that are found in females of the similar forbesii group (Figure 414). Most females of the trizonatum group have an acarinarium on the anterior surface of tergum I, the glabrous surface of which is relatively small and indistinctly delimited by relatively sparse, elongate fringe hairs (Figures 693, 711; the fringe hairs are dense and form a much more sharply defined border in the similar forbesii group, Figures 407–409, and L. morrilli, Figure 525). Females of L. anhypops lack an acarinarium (Figure 85) but can be recognized by the sharply excavated lateral edge of tergum II (Figures 154).

Among species occurring in the western United States, males of the trizonatum group can usually be recognized by their relatively flat clypeal surfaces and their conspicuously elongate heads, which appear longer than broad (Figures 684, 698, 710, length/width ratio x = 0.95–1.02 for four species). The shortest heads are those of L. anhypops (Figure 671, length/width ratio x = 0.93, n = 15). Lasioglossum athabascense males have moderately elongate heads (Figure 289, length/width ratio x = 0.95) but have a broadly rounded clypeal surface and elongate, erect lateral hair tufts on sternum V (Figure 294; these tufts are similar to those of L. egregium where the head is obviously longer (Figure 684, length/ width ratio x = 0.98 and the clypeal surface flat). Other western species with moderately elongate headed males are L. pavonotum, which is metallic blue-green (Figure 585, length/width ratio x = 0.90); L. zonulum, which has a unique vestiture pattern on sternum VI (Figure 744; length/width ratio x = 0.93); L. colatum, which has an obviously rounded clypeal surface and shorter head (Figure 340, length/width ratio x = 0.90); and L. paraforbesii (Figure 435, length/width ratio x = 0.93), which has yellow hind tarsi and very short inconspicuous hairs on sternum V (L. mellipes hind tarsi yellowish orange and sternum V with erect, lateral hair tufts and/or a median rosette of erect hairs (Figures 701, 702). The males of L. channelense, long considered to be conspecific with L. trizonatum, have conspicuously elongate mandibles (Figure 320) and a virtually complete pronotal lateral carina (obviously incomplete in trizonatum males). The most similar male to those of the trizonatum group is that of L. morrilli. The latter species has a very elongate head (length/ width ratio x = 0.95) but can be distinguished by its virtually impunctate and rounded clypeal surface. Furthermore, the gonostylus of L. morrilli is truncate apically (Figure 233), which differs from the narrowly rounded gonostylus of trizonatum males (Figures 234).

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