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Comprehensive Description

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Lasioglossum titusi (Crawford)

Halictus Titusi Crawford, 1902:2 [female]; 1906:302 [locality records],

Lasioglossum titusi.—Michener, 1951:1107 [Nearctic catalog].—Linsley and MacSwain, 1959:22, 29 [flight records, association with Ranunculus, mites].—Linsley et al., 1963:42 [locality and flower records].—Whitsel and Schoeppner, 1971:223 [mites].—Moldenke and Neff, 1974:58 [locality and flower records].—Bohart and Yous—sef, 1976:193 [pollen preference],—Delfinado and Baker, 1976:286 [mites].—Eickwort, 1979:579 [mites].—Hurd, 1979:1958 [Nearctic catalog].—Hurd, et al., 1980:27, 66 [flower records].

TYPE MATERIAL.—The holotype of Halictus titusi could not be located and is presumed to be lost. In his original description, Crawford (1902) stated that “the specimens on which this papier is based are in the collection of the University of Nebraska, unless otherwise stated.” Dr. Brett C. Ratcliffe kindly checked the Nebraska collection but could not locate any type material for this species. Although there are two specimens in the collection of the National Museum of Natural History labeled “cotype,” they lack primary type status, because Crawford's only mention of the type series was “type from San Diego, Calif.” Fortunately, Lasioglossum titusi is a very distinctive bee, and Crawford's original description clearly associates the name with the “cotypes” and other specimens commonly believed to be conspecific. Designation of a neotype is unnecessary.

DISTRIBUTION (Figure 631).—Lasioglossum titusi has heretofore been reported only from California and Oregon (Hurd, 1979). It is now known to occur from southern British Columbia through Washington and south through coastal southern California to Baja California Norte, including East Anacapa, San Miguel, Santa Cruz, and Santa Rosa Islands. To the east the species follows the Rocky Mountain system into northern Utah and western Colorado.

DIAGNOSIS.—Females of Lasioglossum titusi can be readily recognized by their very sparse mesoscutal punctation (Figure 637). The mesoscutum is actually obscurely doubly-punctate with the smaller, inconspicuous punctures separated by 2–4 times their width and the larger punctures separated by 2–3 times their width laterally, becoming extremely sparse centrally. The propodeal dorsal surface is regularly and distinctively striolate (Figure 636) and is unique among western Lasioglossum in being only slightly longer than the metanotum. Additional characters helpful in recognizing L. titusi are the moderately short head (Figure 632), the shiny and sparsely punctate vertex between the lateral ocellus and the compound eye (Figure 124), and the noticeably dull metasoma with relatively inconspicuous gray-white basal hair bands. Furthermore, this is the only Lasioglossum species associated with scutacarid mites that cling to the hairs on the posterior propodeal surface of the female bee (Figure 75; the histiostomatid mites associated with other Lasioglossum females are found on an acarinarium on the anterior surface of the first metasomal tergum of the host).

The mesoscutal punctation of male L. titusi is extremely sparse, more so than that of the female. The punctures are fine and inconspicuous on a highly polished mesoscutal surface. The fine mesoscutal punctation in combination with the yellow tarsi of all three pairs of legs will differentiate L. titusi males from all other North American Lasioglossum (other species with yellow tarsi have well-developed mesoscutal punctation). Also helpful in recognizing males of this species are the regularly striolate dorsal propodeal surface (similar to that of the female. Figure 636) and the relatively simple sternal vestiture (Figure 198).

DESCRIPTION.—FEMALE: Length 7.3–10.0 mm (x = 8.8, n = 15); (2) wing length 2.3–2.7 mm (x = 2.4, ? = 15); (3) abdominal width 2.83.5 mm (x = 3.2, n = 15).

Structure: (4) Head short (Figure 632; length/width ratio 0.85–0.92, x = 0.88, n = 15). (7) Supraclypeal area evenly rounded, (8) very weakly protuberant. (9) Clypeus projecting approximately 0.75 of its length below lower margin of eyes; (11) surface 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 634; (27) distal keel narrow in frontal view, parallel-sided; (28) distal lateral projections well developed, unlike all other species, projections conspicuously truncated; (29) fimbrial setae acutely pointed.

(32) Pronotal lateral angle broadly obtuse; (33) pronotal lateral ridge incomplete, broadly interrupted by oblique lateral sulcus; (34) lower portion of lateral ridge inconspicuous, broadly rounded. (35) Mesoscutal lip rounded, not bilobed, (36) moderately elevated from pronotum. (40) Dorsal surface of propodeum very short, about 0.54 the length of scutellum and subequal to metanotum in length, (41) not depressed centrally, (42) posterior margin broadly rounded; (43) propodeal triangle weakly defined, evident medially as a low V-shaped elevation with weak lateral rims extending towards metanotum; (44) lateral carinae extending nearly to dorsal surface. (45) Tibial spur as in Figure 54.

(46) Unlike other species, lateral edge of metasomal tergum II broadly and evenly rounded (Figure 62).

Sculpture: (47) Face shiny, (48) densely punctate below ocelli (somewhat granular immediately below median ocellus), punctures contiguous, becoming larger and less dense near antennae. (51) Supraclypeal area extremely granulate; (52) uniformly but sparsely punctate, punctures separated by 3–4 times their width. (53) Clypeus granulate basally, obscurely granulate over apical two-thirds; (54) punctures minute basally, larger apically, uniformly separated by their width. (56) Mesoscutum dull; (57) punctation as in Figure 637, indistinctly doubly-punctate, smaller punctures very fine, inconspicuous, 2–4 times their width apart, larger punctures separated by 2–3 times their width laterally, becoming extremely sparse centrally. (58) Scutellum virtually impunctate adjacent to median line, punctures extremely fine and scattered. (63) Dorsal surface of propodeum (Figure 636) irregularly but distinctly striolate, striae reaching posterior margin; (64) surface very obscurely alveolated. (65) Metasomal tergum I dull, not noticeably granulate; (66) punctation very fine, obscure, moderately dense, punctures 1–2 times their width apart.

Coloration: (71) Wing membrane mostly hyaline, very obscurely infuscated towards apex.

Vestiture: (74) Pubescence of head pale yellowish brown. (75) Pubescence of thorax pale yellowish brown; (76) mesoscutal hairs somewhat dense, conspicuously plumose. (77) Hind tibial hairs concolorous, pale yellowish brown. (78) Anterior hairs of metasomal tergum I pale yellowish white, (79) basal hair bands of terga II–IV grayish white. (80) Acarinarium absent, elongate hairs scattered over anterior surface of tergum I (mites cling to propodeal hairs).

MALE: Similar to female except as follows: (1) length 7.1–8.5 mm (x = 7.9, n = 15); (2) wing length 1.9–2.5 mm (x = 2.3, n = 15); (3) abdominal width 2.0–2.9 mm (x = 2.6, n = 15). (4) Head as in figure 633 (length/width ratio 0.790.91, x = 0.85, n = 15). (5) Gena slightly wider than eye, (6) rounded, not produced posteriorly. (10) Clypeal surface broadly rounded, not flattened or depressed. (23) Unlike most species, flagellomere 1 relatively long compared to flagellomere 2 (ratio 1:2 approximately 0.87). Labrum as in Figure 635; (24) distal process absent; (25) basal area rounded medially, not depressed; (26) basal lateral depressions very weakly developed. (30) Mandible short, just reaching opposing clypeal angle. (53) Clypeus polished; (54) punctation nearly uniform throughout, punctures separated by 1–2 times their width. (68) Clypeal maculation usually present, sometimes reduced or rarely absent. (69) Flagellum entirely dark or light brown ventrally and contrasting with dark dorsum. (72) Tarsi yellow, contrasting with dark tibiae.

Vestiture: Sternal vestiture as in Figure 198; (82) hairs on sternum IV moderately short, suberect, without noticeable pattern; (83) hairs on sternum V mostly short, inconspicuous except for small patch of erect hairs on lateral edge of sternum and characteristic fringe of short hairs along the posterior sternal edge.

Terminalia: Sterna VI I–VIII as in Figure 643; (85) sternum VIII without median process. Genitalia as in Figures 638–642; (86) gonobase moderately elongate; (87) gonostylus robust, broadly rounded to truncate apicially, surface conspicuously concave as viewed ventrally; (89) retrorse membranous lobe very slender basally, expanding to moderately broad distal portion (unlike other species, inner margin of lobe with row of conspicuously large, plumose setae); (90) volsella broadly rounded laterally, lacking prominent lobe.

FLIGHT RECORDS (Figure 644).—Female L. titusi have been collected in every month; however, 74% of the specimens examined were collected from May to July. Female records from the southwest region peak in late May, whereas those from the northwest peak in late June. The two specimens collected in November and January were from Riverside County, California; the one specimen collected in December was from Yolo County in the Central Valley of California. Male records are most common from July to September but range from May to early November, with one male collected on 11 January 1926, by P.H. Timberlake in Riverside, California.

FLOWER RECORDS.—Lasioglossum titusi is unusual among Lasioglossum species in showing some level of oligolectic behavior. This was first mentioned by Bohart and Youssef (1976), who stated that this species “collects pollen only from ligulate composites (unpublished).” Hurd, LaBerge, and Linsley (1980) reported this species as being a “casual polylege” of Helianthus. Of the 374 females examined in this study that had associated floral data, 312 (83%) were collected on composite flowers; 112 of these specimens were noted to have full or nearly full scopal pollen loads and 111 of them were taken on composites (one was taken from Calochortus). Although the relationship between floral label data and actual source of scopal pollen are tenuous without pollen analysis, the obvious trend in this case is highly supportive of Bohart and Youssef's claim for oligolecty.

Summary: Females (365): Compositae 83%; Ranunculaceae 3%. Males (29): Compositae 93%; Plantaginaceae 7%. Total: 394 in 17 families, 53 genera as follows:

*Agoseris 78(5); Anthemis 3; *Aster 6(1), 1; Astragalus 1; Baeria 8; Balsamorhiza 1; *Blennosperma 6(2); Blepharipappus 15; Brassica 5; * Calochortus 1(1); Calycadenia 1, Ceanothus 1; Chrysanthemum 1; Chrysothamnus 1, 2; Cichorium 3; Clarkia 2; Convolvulus 1; * Cosmos 7(7); * Crepis 1(1); Cryptantha 7; Encelia 4; Fritillaria 1; Godetia 1; Grindelia 6, 2; *Helianthus 28(24); *Hemizonia 12(3), 11; Heterotheca 1; Hypericum 1; *Hypochaeris 56(37); *Lasthenia 9(4); *Layia 19(11), 4; Limnanthes 1; Lomatium 1; *Madia 7(5), 1; Malacothrix 1; Melilotus 2; Mentha 1; Mesembryanthemum 1; Nemophila 2; Parthenium 21, 3; Picris 2, 1; Plantago 2; Ranunculus 15; Salix 1; Sisymbrium 1; *Solidago 1(1); Stenotopsis 1; Stephanomeria 1, 1; Taraxacum 13; Trifolium 1; Triteleia 3; *Wyethia 2(1).

MITE ASSOCIATES.—Unlike other species of New World Lasioglossum, L. titusi is associated with a scutacarid mite, Imparipes vulgaris Delfinado and Baker (Linsley and MacSwain, 1959; Delfinado and Baker, 1976; Eickwort, 1979). See introductory section on “Mite Associations” for further details.

SPECIMENS EXAMINED.—1473 (1315, 158).

CANADA. BRITISH COLUMBIA: Vernon 19 Sep 1903 (1; USNM).

MEXICO. BAJA CALIFORNIA NORTE: Rio San Miguel, 22 Aug 1981, D.K. Faulkner (1; SDNHM).

UNITED STATES. CALIFORNIA: Alameda Co.; Butte Co.: Biggs, 4 mi N; Alpine Co.: Monitor Pass Summit; Amador Co.: Fiddletown (4 mi E), Sutter Creek; Calveras Co.: Murphys, Railroad Flat; Colusa Co.: Bear Valley, Lodoga, 4 mi NW; Contra Costa Co.; El Dorado Co.: Shingle Springs; Fresno Co.: unspecified locality; Humboldt Co.; Kings Co.: Corcoran; Lake Co.: Lakeport, Lower Lake (11 mi W); Lassen Co.: Hallelujah Junction, Litchfield (10.6 mi N), Termo (6.5 mi N); Los Angeles Co.; Madera Co.: Bass Lake; Marin Co.; Mariposa Co.: Miami Ranger Station; Mendocino Co.; Modoc Co.; Monterey Co.; Napa Co.; Orange Co.; Placer Co.: Dutch Flat, Weimar (3 mi W); Plumas Co.: Meadow Valley, Quincy (4 mi W, 23 mi SW); Riverside Co.; Sacramento Co.; San Francisco Co.; San Benito Co.: Pinnacles, west side; San Diego Co.: La Jolla, San Diego, Warner Springs (2 mi N); San Luis Obispo Co.: Atascadero (8 mi W), Cambria Pines, Morro Bay, Pismo; San Mateo Co.; Santa Barbara Co.: includes San Miguel and Santa Rosa islands; Santa Clara Co.; Santa Cruz Co.; Shasta Co.: Redding; Sierra Co.: Gold Lake, Sattley; Siskiyou Co.: Weed; Solano Co.: Dixon (11 mi S), Vacaville (11 mi N), Vallejo; Sonoma Co.; Stanislaus Co.: Turlock; Tulare Co.: Ash Mountain; Trinity Co.: Hayfork; Tuolumne Co.; Ventura Co.: East Anacapa Island, Matilija; Yolo Co.: Davis, Putah Canyon, Woodland; Yuba Co.: Marysville.

COLORADO: Delta Co.: Paonia; Routt Co.: Craig (10 mi E), Steamboat Springs (11 mi NNW). IDAHO: Bannock Co.: Arimo (6 mi W); Franklin Co.; Gem Co.: Squaw Creek (10 mi E. Emmett); Latah Co.: Juliaetta (3 mi SW), Troy; Nez Perce Co.: top of Lewiston Grade; Oneida Co.: Ireland Canyon, Salyer Cow Camp; Owyhee Co.: Sheaville, 4 mi E. MONTANA: Carbon Co.: Roscoe (3 mi SSW); Gallatin Co.: Bozeman; Judith Basin Co.: Raynesford (8 km W). NEVADA: Douglas Co.: Topaz Lake; Washoe Co.: near Wadsworth. OREGON. Baker Co.: Sparta: Benton Co.; Clackamas Co.: Mt. Hood; Columbia Co.: Clatskanie, Scappoose; Coos Co.: Fairview (5 mi NE Coquille); Crook Co.: Prineville (25 mi E); Curry Co.: Gold Beach, Sixes River; Deschutes Co.: Three Sisters; Douglas Co.; Harney Co.: Burns (20 mi E), Frenchglen (9 mi E); Jackson Co.; Josephine Co.: Grave Creek; Klamath Co.: Dairy (10 mi E), Klamath Falls; Lake Co.: Warner Canyon; Lane Co.: Cottage Grove, Eugene; Lincoln Co.: Eddvville, Siletz; Linn Co.: Scio (12 mi E); Marion Co.: Salem, Woodburn; Multnomah Co.: Portland; Polk Co.: Kings Valley (2 mi N), Monmouth; Tillamook Co.: Oceanside. Tillamook Burn: Umatilla Co.: S. Pendleton, near Ukiah. Morrow-Umatilla Co. boundary on US 74; Union Co.: Minam Hill (10 mi E. Elgin); Wallowa Co.: Florsa Lake; Wasco Co.: Mosier Creek; Washington Co.: Forest Grove, Hillsboro.

UTAH: Box Elder Co.: Mantua-Devil's Gate; Cache Co.: High Creek, Logan, Tony Grove Junction; Salt Lake Co.: Parleys Canyon, Salt Lake City: Summit Co.: Wanship. WASHINGTON: Grays Harbor Co.: Markham; Island Co.: Whidby Island (2 mi NE Oak Harbor); Klickitat Co.: Lyle (5 mi NE); Pierce Co.: Puyallup; Thurston Co.: Olympia; Walla Walla Co.: Walla Walla; Whitman Co.: Pullman. WYOMING: Fremont Co.: Lander: Teton Co.: Wilson (15 mi S).
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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

Lasioglossum titusi

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Lasioglossum titusi is a species of sweat bee in the family Halictidae.[1][2][3]

References

  1. ^ "Lasioglossum titusi Report". Integrated Taxonomic Information System. Retrieved 2019-09-24.
  2. ^ "Lasioglossum titusi". GBIF. Retrieved 2019-09-24.
  3. ^ "Lasioglossum titusi species Information". BugGuide.net. Retrieved 2019-09-24.
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Lasioglossum titusi: Brief Summary

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Lasioglossum titusi is a species of sweat bee in the family Halictidae.

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