Lasioglossum (Dialictus) platyparium (Robertson)

Halictus platyparius Robertson, 1895: 117 . Ƥ.

Lectotype. Ƥ USA, Illinois, Macoupin Co. Carlinville, 18.v.1887 (C. Robertson); [INHS: 3995] by W. E. LaBerge (in Webb 1980). Examined.

Taxonomy. Robertson, 1901: Paralictus platyparius, p. 229 (generic description); Michener, 1951: Lasioglossum (Paralictus) platyparium, p. 1119 (catalogue); Mitchell, 1960: Paralictus platyparius Ƥ3, p. 448 (redescription); Krombein, 1967: Lasioglossum (Paralictus) platyparium, p. 467 (catalogue); Paralictus platyparius, p. 1974 (catalogue); Moure & Hurd, 1987: Paralictus platyparius, p. 143 (catalogue); Gibbs, 2010b: Lasioglossum (Dialictus) platyparium Ƥ3, p. 261 (redescription, key).

Diagnosis. Female L. platyparium can be recognised by the following diagnostic combination: scopa absent; gena wider than eye; mandible large, converging to point only near apex, distinct preapical tooth absent; labrum with distinct basal tubercle, apical process flat, dorsal keel absent (Fig. 6 B); and metapostnotum rugoso-carinulate. They are similar to L. cephalotes and L. rozeni . Female L. rozeni have a narrow mandible that is evenly convergent along its entire length and lacks a distinct basal tubercle on the labrum. Female L. cephalotes lack a distinct basal tubercle on the labrum and have a smooth metapostnotum without evident rugae.

Male L. platyparium can be recognised by head wide (length/width ratio = 0.95–0.96), dorsolateral angle of pronotum acute, pronotal collar weak, and mesepisternum rugulose.

Range. Ontario south to Georgia, Louisiana and west to Minnesota. USA: DC, GA, IL, KS, LA, MD, MN, MO, NC, PA, WV, WI. CANADA: ON.

DNA Barcode. Available. Multiple sequences.

Comments. Uncommon.

Lasioglossum platyparium is presumed to be a social parasite of nest-building Dialictus . It is perhaps the most commonly collected of the parasitic L. ( Dialictus) but its host species remains unknown.