Comprehensive Description

provided by Smithsonian Contributions to Zoology
Lasioglossum colatum (Vachal)

Halictus colatus Vachal, 1904:476 [male].—Cockerell, 1907:242 [incorrect synonymy with H. trizonatus].

Halictus ripariellus Cockerell, 1918b:261 [female]. [New synonymy.]

Lasioglossum ripariellum.—Michener, 1951:1107 [Nearctic catalog].—Hurd, 1979:1958 [Nearctic catalog].

TYPE MATERIAL.—The male holotype of Halictus colatus is in the Naturhistorisches Museum, Vienna. It is labeled

Morrison [Jefferson County] Colorado 1879. [indecipherable character]/colatus Vach[al] det. J. Vachal/Hal[ictus] colatus Vach[al] [handwritten].

The specimen is in fair condition; it is missing the last 10 flagellomeres of the right antenna and has had the head and pronotum glued to the thorax. When received for study in September 1983, the abdomen was loosely connected to the thorax and was secured with a small drop of polyvinyl acetate.

The female holotype of Halictus ripariellus is in the California Academy of Sciences, San Francisco. It is labeled

Holotype [on red label]/Florissant [Teller County], Colo.[rado] Expedition 1907. Coll.[ector] Ckll. [Cockerell] June 26/nesting in bank [handwritten by Cockerell]/Halictus ripariellus Ckll. TYPE. [handwritten by Cockerell].

The specimen is missing the last two tarsomeres of the left hind leg and the last tarsomere of the right hind leg but otherwise is in excellent condition.

DISTRIBUTION (Figure 338).—Both Nearctic catalogs reported Lasioglossum colatum only from Colorado. It is now known to occur widely in the West from southern British Columbia and Edmonton, Alberta, south to southern Utah and Colorado and through the Sierra Nevada to Alpine County, California. Eastern-most records are from Wyoming and central Colorado, with one female collected from Hanna (Meade Co.), South Dakota, in 1936 (Cornell University Collection).

DIAGNOSIS.—Females of Lasioglossum colatum can be recognized by their weakly developed but distinctive acarinarium on the anterior surface of the first metasomal tergum (Figure 351): elongate lateral fringe hairs are present but are sparse and form only an indistinct border around the central glabrous area; furthermore, a distinctive patch of short, adpressed hairs is present in the dorsal acarinarial opening. Other characters useful in recognizing L. colatum are the relatively sparse mesoscutal punctation that is obscurely doubly-punctate (Figure 344) and the moderately short head (Figure 339; length/width ratio 0.88–0.96, x = 0.92). Lasioglossum colatum females are most commonly confused with those of the forbesii and trizonatum groups; however, the acarinarium in the latter species is more strongly developed in having conspicuous lateral hair fringes (Figures 111, 114) and the mesoscutal punctation of both species is denser than that of L. colatum (Figures 439, 675). Lasioglossum forbesii, sensu lato, can further be differentiated from L. colatum in having the posterior rim of the dorsal propodeal surface slightly elevated (Figure 438; rounded in L. colatum, Figure 343). The elongate heads of L. trizonatum, sensu lato, (Figures 683, 709) will readily separate them from L. colatum.

The male of Lasioglossum colatum has a round, short head (Figure 340) and a broadly rounded clypeus (not flattened as in most other Lasioglossum males). Also diagnostic is the elongate, slender tergum I as seen from above (Figure 343). Males of L. athabascense also have a rounded head and a rounded clypeus but differ in having long, erect hair tufts on the lateral edges of sternum V (Figure 294).

DESCRIPTION.—FEMALE: (1) Length 7.4–9.8 mm (x = 8.3, n = 15); (2) wing length 2.3–2.7 mm (x = 2.4, n = 15); (3) abdominal width 2.4–2.8 mm (x = 2.7, n = 15).

Structure: (4) Head moderately short (Figure 339); length/width ratio 0.88–0.96, x = 0.92, n = 15. (7) Supraclypeal area evenly rounded, (8) moderately protuberant. (9) Clypeus projecting approximately 0.84 of its length below lower margin of eyes; (11) surface slightly protuberant towards ventral edge, without median longitudinal sulcation. (14) Distance between lateral ocelli subequal to distance between lateral ocellus and eye. (23) Flagellomere 1 longer than 2 along dorsal surface. Labrum as in Figure 341; (27) distal keel narrow in frontal view, nearly parallel-sided; (28) distal lateral projections 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 inconspicuous, broadly rounded. (35) Mesoscutal lip weakly bilobed, (36) moderately elevated from pronotum. (40) Dorsal surface of propodeum about 0.88 the length of scutellum and about 1.7 times the length of metanotum, (41) slightly depressed centrally, (42) posterior margin rounded; (43) propodeal triangle weakly impressed, evident medially as an inconspicuous V-shaped elevation with low lateral rims; (44) lateral carinae extending to midpoint of posterior surface. (45) Tibial spur as in Figure 26.

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

Sculpture: (47) Face shiny, (48) densely punctate below ocelli, punctures contiguous, becoming larger and less dense near antennae. (51) Supraclypeal area very weakly granulate, nearly polished; (52) punctures separated by their width laterally, becoming impunctate centrally. (53) Clypeus polished or at most obscurely granulate over basal third; (54) punctation sparse, punctures separated by 1–2times their width basally, nearly impunctate apicolaterally. (56) Mesoscutum moderately shiny; (57) punctation as in Figure 344, doubly-punctate, smaller punctures 1–3 times their width apart, larger punctures 3–5 times their width apart, less dense centrally. (58) Scutellum sparsely punctate adjacent to median line, punctures 2–3 times their width apart. (63) Dorsal surface of propodeum (Figure 343) striolate laterally, becoming ruguloso-striolate to finely rugulose medially, striae and rugulae reaching posterior margin; (64) surface obscurely alveolated. (65) Metasomal tergum I moderately shiny; (66) punctation fine, dense, punctures slightly less than their width apart.

Coloration: (71) Wing membrane pale yellowish brown.

Vestiture: Pubescence of head pale yellowish brown. (75) Pubescence of thorax white to pale yellowish brown; (76) mesoscutal hairs moderately sparse, not conspicuously plumose. (77) Hind tibial hairs concolorous, pale yellowish brown. (78) Anterior hairs of metasomal tergum I and (79) basal hair bands of terga II–IV white. (80) Acarinarium present but weakly defined (Figure 351), a small glabrous area at base of tergum I surrounded laterally by scattered elongate hairs, not forming distinct fringe; short, adpressed hairs present dorsolaterally; opening of acarinarium wide, indistinctly defined, wider than lateral hair fringe as seen in dorsal view.

MALE: Similar to female except as follows: (1) length 6.5–8.3 mm (x = 7.1, n = 15); (2) wing length 1.8–2.1 mm (x = 2.0, n = 15); (3) abdominal width 1.8–2.1 (x = 2.0, n = 15). (4) Head as in Figure 340 (length/width ratio 0.86–0.95, x = 0.90, n = 15). (5) Gena slightly wider than eye, (6) moderately produced posteriorly. (10) Clypeal surface noticeably rounded dorsally, contrasting with shallow ventral depression. Labrum as in Figure 342; (24) distal process weakly developed, broadly to narrowly rounded; (25) basal area depressed medially; (26) basal lateral depressions present, moderately developed. (30) Mandible short, just reaching opposing clypeal angle. (53) Clypeus polished; (54) punctures well formed and dense along basal edge, apical two-thirds virtually impunctate, punctures very fine and scattered. (68) Clypeal maculation present (Figure 340). (69) Flagellum light brown ventrally, contrasting with dark dorsum. (72) Tarsi dark, concolorous with tibiae.

Vestiture: Sternal vestiture as in Figure 345; (82) hairs on sternum IV erect, longer at midline than laterally; (83) sternum V with median rosette of moderately short, erect hairs that become longer laterally, erect hairs reaching lateral margin of sternum or with erect hairs confined to central portion of sternum.

Terminalia: Sterna VII–VIII as in Figure 350; (85) sternum VIII with short, narrowly rounded median process. Genitalia as in Figures 346–349; (86) gonobase moderately elongate; (87) gonostylus broad, apex narrowly rounded; (89) retrorse membranous lobe narrow, parallel-sided; (90) volsella with very prominent lateral lobe.

FLIGHT RECORDS (Figure 352).—Lasioglossum colatum females have been collected from March through early October, with most records coming from June and July, with a peak in early July. The one female taken in March was from Franklin County, Idaho (8 Mar 1969); the one October record is from Nez Perce County, Idaho (1 Oct 1944). Males have been taken from July through early September.

FLOWER RECORDS.—Females (21): Compositae 61%; Salicaceae 17%. Total: 21 in six families, eight genera as follows:

Clematis 1; Euphorbia 2; Rosa 1; Rudbeckia 1; Salix 2; Scrophularia 1; Senecio 1 Taraxacum 12.

MITE ASSOCIATES.—Although the acarinarium of L. colatum is only very weakly developed (Figure 351), 17 (6.8%) of the females examined were associated with phoretic mites.

SPECIMENS EXAMINED.—277 (265, 12).

CANADA. ALBERTA: Drumheller, Edmonton, Elkwater, Medicine Hat. BRITISH COLUMBIA: Fernie, Lillooet, OK Falls, Summerland.

UNITED STATES. CALIFORNIA: Alpine Co.: Markleeville, Woodfords; Fresno Co.: Pioneer Basin; Lassen Co.: Hallelujah Junction; Modoc Co.: Davis Creek; Plumas Co.: Frenchmans Lake. COLORADO: Archuleta Co.: Pagosa Springs; Boulder Co.: Boulder; Jefferson Co.: Morrison; Moffat Co.: Lay; Ouray Co.: Ouray; Routt Co.: Columbine (4 mi N), Steamboat Springs (4 mi E); Teller Co.: Florissant. IDAHO: Adams Co.: Council, New Meadows; Cassia Co.: Elba-Basin Pass, Oakley, 5 min NW: Franklin Co.; Fremont Co.: St. Anthony; Latah Co.; Nez Perce Co.: Lewiston; Oneida Co.; Owyhee Co.: Little Valley; Twin Falls Co.: Magic Mt., near Twin Falls. MONTANA: Flathead Co.: Glacier National Park, West Glacier; Gallatin Co.: Bozeman, Squaw Creek.

NEVADA: Carbon Co.: Rosebud Canyon; Douglas Co.: Dagget Pass; Elko Co.: Deeth, Lamoile Lake; Eureka Co.: Red House Ranch; Humboldt Co.: Lye Creek Camp (18 mi N Paradise Valley); Lander Co.: Austin Summit (2.5 mi E), Blackbird Ranch (10 mi SE Austin). OREGON: Benton Co.: Alsea Mount, Corvallis; Grant Co.: Sheep Mt. Road, Summit Prairie; Harney Co.: Fish Lake (16 mi E Frenchglen), Frenchglen, North Fork Malheur River; Wallowa Co.: Minam State Park. SOUTH DAKOTA: Meade Co.: Hanna. UTAH: Box Elder Co.; Cache Co.; Daggett Co.; Davis Co.: Framington; Millard Co.: Fillmore; Salt Lake Co.: Parleys Canyon, Salt Lake City; San Juan Co.: Hide Out Canyon; Sanpete Co.: Indianola; Summit Co.: Wanship; Weber Co.: Liberty, Willard Basin, Wolf Creek. WASHINGTON: Asotin Co.: Asotin; King Co.: Maple Valley; Stevens Co.: Colville, 4 mi S; Thurston Co.: Olympia; Walla Walla Co.: Walla Walla; Whitman Co.: Pullman. WYOMING: Albany Co.: Laramie, Medicine Bow National Forest; Fremont Co.: Lander; Teton Co.: Grand Teton National Park; Uinta Co.: unspecified locality.
bibliographic citation
McGinley, R. J. 1986. "Studies of Halictinae (Apoidea: Halictidae), I: Revision of New World Lasioglossum Curtis." Smithsonian Contributions to Zoology. 1-294. https://doi.org/10.5479/si.00810282.429