Lasioglossum (Dialictus) viridellum (Cockerell, 1931)

Halictus (Chloralictus) viridellus Cockerell 1931: 14 [Holotype: American Museum of Natural History, New York, USA, ♀, type locality = Shanghai, China].

Lasioglossum (Evylaeus) viridellum: Ebmer 1978b: 312; Ebmer 1996: 283; Ebmer 2006: 568. Evylaeus (Aerathalictus) viridellus: Pesenko 2007b: 85 (in key), 97 (in key), 114, Figs 104–06 (♂). Lasioglossum (Dialictus) viridellum: Murao et al. 2015a: 9, 44 (in key), Figs 1, 2A –E, 3B (♀ ♂).

Diagnosis. This species is separated from other East Asian members of the aeratum group by a combination of the following character states: male clypeus entirely black, without yellow spot; female T1 basally with thin appressed hairs and basally to medially with strong lineolation (Murao et al. 2015a, Fig. 25A); male metasomal sterna with sparse and uniform hairs. Males of both this species and L. pseudannulipes (Blüthgen) cannot be clearly separated (Murao et al. 2015a).

Distribution. North Korea, South Korea, Russian Far East, China.

Flight period in South Korea. Female: April to September. Male: September.

Flower records in South Korea. The floral records are reported as two species in two families by Murao et al. (2015a).