Lasioglossum (Dialictus) helianthi ( Cockerell, 1916 ), 2022

Gardner, Joel & Gibbs, Jason, 2022, New and little-known Canadian LasIOGLOssum (DIaLICTus) (Hymenoptera: Halictidae) and an emended key to species, The Canadian Entomologist (e 3) 154 (1), pp. 1-37 : 6-7

Lasioglossum (Dialictus) helianthi ( Cockerell, 1916) new combination

Figure 2

Halictus helianthi Cockerell 1916: 77 (holotype, ♀, deposited in USNM; examined)

Lasioglossum (Dialictus) imbrex Gibbs 2010: 153 (holotype, ♀, deposited in PCYU; examined) new synonymy

Diagnosis. Males of L. helianthi can be recognised by the combination of tegula enlarged (reaching but not exceeding posterior margin of mesoscutum in dorsal view), with inner posterior margin weakly concave, coming to a narrow point posteriorly, and usually densely punctate (IS ≤ 1 PD); mesoscutum densely punctate (IS ≤ 1 PD) especially laterad of parapsidal line (IS <0.5 PD); metapostnotum shiny with strong anastomosing rugae; and discs of T1–T2 deeply and densely punctate in basal half (IS ≤ 1 PD). They are most similar to L. tegulariforme and L. ellisiae . Males of L. tegulariforme have the tegula larger (clearly exceeding posterior margin of mesoscutum in dorsal view) with a broadly rounded projection posteriorly, and discs of T1–T2 (especially T1 medially) more sparsely punctate (IS = 1–3 PD). Males of L. ellisiae have the metapostnotum with parallel or subparallel rugae and are also found east of the Rocky Mountains and therefore are very unlikely to occur sympatrically with L. helianthi .

Comments. Lasioglossum helianthi is herein resurrected from synonymy with L. tegulariforme ( Crawford, 1907) , and L. imbrex Gibbs, 2010 is considered a junior subjective synonym (see comments on L. tegulariforme for details).

Figures

Fig. 2. Lasioglossum helianthi (Cockerell, 1916) (♂): A, dorsal habitus; B, lateral habitus; C, face; and D, metasoma. Scale bars: 1 mm.