Lasioglossum (Dialictus) sheffieldi Gibbs, 2010 b: 302. Ƥ 3.
Holotype. Ƥ CANADA, Nova Scotia, Kings Co., Avonport, N 45.1198 W064.2730, 18.vii. 2002 (C. Sheffield); [PCYU].
Diagnosis. Female L. sheffieldi can be recognised by the following diagnostic combination: head moderately long (length/width ratio = 1.00– 1.01); mesoscutum tessellate, punctures dense except medially (Fig. 13 B); mesepisternum shining, irregularly punctate; metapostnotum with strongly anastomosing rugae; T 1 acarinarial fan complete dorsally; metasomal terga polished with faint metallic reflections; and T 3 –T 4 with moderately dense tomentum. They are similar to L. perpunctatum, which has a wider head (length/width ratio = 0.95–0.96) and dense mesoscutal punctures medially (Fig. 13 A).
Male L. sheffieldi can be recognised by the following diagnostic combination: head long (length/width ratio = 1.06– 1.08), dense facial tomentum limited to lower paraocular area, flagellomeres relatively short (length/width ratio = 1.20– 1.62), mesoscutal punctures sparse between parapsidal lines (i= 1–3 d), mesepisternum with distinct punctures, tegula with weak posterior angle, and apical impressed areas of metasomal terga pale translucent yellow, distinctly punctate. They are similar to L. perpunctatum, which has a wider head (length/width ratio = 1.00– 1.03).
Range. Coastal dunes of Nova Scotia, southern Newfoundland, west to Quebec. Disjunct individuals from western coast of Lake Michigan and Manitoba dunes. USA: WI. CANADA: MB, NB, NF, NS, PQ.
DNA Barcode. Available. Multiple sequences.
Comments. Locally common. Lasioglossum sheffieldi is a sand dune specialist.