Lasioglossum (Dialictus) lineatulum (Crawford)

Halictus lineatulus Crawford 1906: 5 . Ƥ.

Holotype. Ƥ USA, Michigan, Ag. Coll., 5.x.1893 [10.v.1893] (R.H. Wolcott); [NMNH: 12071]. Examined. Halictus subconnexus Ellis 1915: 291 . Ƥ.

Holotype. USA, Wisconsin, Milwaukee, 29.v.1903 (S. Graenicher); [UCMC]. Halictus (Chloralictus) latus Sandhouse, 1924: 20 . Ƥ.

Holotype. Ƥ USA, Colorado, Colorado Springs, 20.iv., on willow (W.P. Cockerell), [NMNH: 26414]. Examined. Halictus (Chloralictus) unicus Sandhouse, 1924: 21 . Ƥ.

Holotype. Ƥ USA, Iowa, Seven miles east of Vinton, 29.vi.1922 (G. Sandhouse), [NMNH: 26415]. Examined.

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) latum, p. 1114, L. (C.) lineatulum, p. 1114 (catalogue, Timberlake synonymy); Mitchell, 1960: Dialictus lineatulus Ƥ3, p. 403, D. unicus Ƥ3, p. 425 (redescription);; Krombein, 1967: Lasioglossum (Dialictus) lineatulum, p. 464, L. (D.) unicum, p. 466 (catalogue); Hurd, 1979: Dialictus latus, p. 1967, D. lineatulus, p. 1968, D. unicus, p. 1972 (catalogue); Moure & Hurd, 1987: Dialictus latus, p. 110, D. lineatulus, p. 110, D. unicus, p. 136 (catalogue); Gibbs, 2010b: Lasioglossum (Dialictus) lineatulum Ƥ3, p. 180 (redescription, key, synonymy).

Diagnosis. Female L. lineatulum can be recognised by the following diagnostic combination: head wide (length/ width ratio = 0.92–0.93); clypeus weakly protruding below suborbital tangent; mesoscutal punctures sparse, including laterad of parapsidal lines (Fig. 4 I); mesepisternum rugulose; propodeum with dorsolateral slopes smooth; (Figs. 2 C, 27A) and metasomal terga often with metallic reflections. They are most similar to L. novascotiae, which has head longer (length/width ratio = 0.95–0.96), clypeus strongly protruding below suborbital tangent, propodeum with dorsolateral slopes rugulose (Fig. 27 B), and metasomal terga without metallic reflections.

Male L. lineatulum can be recognised by the following diagnostic combination: mesoscutal punctures sparse laterad of the parapsidal lines, and S2–S4 and S5 laterally with dense plumose hairs. They are similar to L. novascotiae have subappressed plumose hairs limited to the apicolateral portions of S3 and lateral portions of S4–S5.

Range. Nova Scotia west to Alberta, south to Georgia. USA: CT, CO, GA, IA, MA, MD, ME, MI, MN, NC, NJ, NY, PA, VT, WI, WV. CANADA: AB, MB, ON, PQ, SK.

DNA Barcode. Available. Multiple sequences.

Comments. Common.

Lasioglossum lineatulum forms eusocial colonies (Eickwort 1986).

The location of the holotype of Halictus subconnexus was previously unknown. At the time of the original description Ellis was working from Boulder, Colorado so the type specimen was likely deposited at UCMC. A specimen was discovered at UCMC with identical locality information to the type specimen designated by Ellis (1915). The specimen has a label reading “ Halictus subconnexus Ellis ” in Ellis’ handwriting. It is believed that this specimen is the original type. A type label has been affixed to the specimen.