Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini) Author Gibbs, Jason text Zootaxa 2011 2011-10-28 3073 1 216 journal article 31531 10.5281/zenodo.1049595 1a985cc7-af57-45e9-a988-c3beda3c15b4 1175-5326 1049595 B5AF6DF4-D3A7-4942-A94F-CC051D8074CF Lasioglossum ( Dialictus ) ephialtum Gibbs Lasioglossum ( Dialictus ) ephialtum Gibbs, 2010b : 124 . Ƥ3. Holotype . Ƥ CANADA , Ontario, Toronto, Brunswick Ave., N43.66165 W079.40571 , 6.x.2006 (J. Gibbs); [ PCYU ]. Diagnosis. Female L . ephialtum can be recognised by the following diagnostic combination: head moderately wide to round (length/width ratio = 0.95–0.99); mesoscutum imbricate, punctures moderately sparse between parapsidal lines (i=1–2d); mesepisternum rugulose-imbricate; metapostnotal rugae reaching, or nearly reaching, posterior margin; metasomal terga brown, polished due to weak microsculpture; T1 acarinarial fan with distinct dorsal opening; T2–T4 basolaterally with moderately dense tomentum; and T3–T4 with moderately dense apical fringes. They are similar to L . planatum , which has shorter metapostnotal rugae except for a single long medial carina, and less abundant pubescence on the metasomal terga. Male L . ephialtum are similar to females but may be further distinguished by flagellomeres elongate (length/width ratio = 1.80–1.85), mesoscutum weakly imbricate, tarsi brownish yellow, metapostnotum strongly rugose, metasomal terga impunctate on apical halves, T2–T4 basolaterally with sparse tomentum, and S2–S5 apicolaterally with moderately dense pubescence. They are similar to L . laevissimum and L . mitchelli . Male L . laevissimum lack tomentum on the metasomal terga and have obscure punctures on the lower portion of the mesepisternum. Male L . mitchelli have denser punctures on the metasomal terga that are only absent on the apical impressed areas and the mesoscutum tessellate. Range. New Brunswick south to West Virginia, west to Manitoba, Colorado. USA : CO, CT, DC, IL , IA, IN, MA, MD, ME, MN, NH, NJ, NY, PA, WI, WV. CANADA : NB, NS, ON, PQ. DNA Barcode. Available. Multiple sequences. Comments. Common.