Lasioglossum (Dialictus) subviridatum (Cockerell)

Gibbs, Jason, 2011, Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini), Zootaxa 3073, pp. 1-216 : 184-185

Lasioglossum (Dialictus) subviridatum (Cockerell)

Halictus (Chloralictus) subviridatus Cockerell, 1938a: 2 . Ƥ 3.

Holotype. Ƥ CANADA, Saskatchewan, Lake Ajawaan, 26.viii.1936, (Cockerell); [ AMNH]. Examined.

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) subviridatum , p. 1118 (catalogue); Dialictus subviridatus , p. 1972 (catalogue); Moure & Hurd, 1987: Dialictus subviridatus , p. 132 (catalogue); Gibbs, 2010b: Lasioglossum (Dialictus) subviridatum Ƥ3, p. 313 (redescription, key).

Diagnosis. Female L. subviridatum can be recognised by the following diagnostic combination: head wide (length/ width ratio = 0.93–0.96); mesoscutum polished due to weak microsculpture, punctures moderately sparse between parapsidal lines (i=1–2.5d); tegula brownish yellow; mesepisternum weakly rugulose, relatively shiny; metapostnotum strongly rugoso-carinulate; T1 polished due to lack of microsculpture; T1 acarinarial fan small with very wide dorsal opening; metasomal terga brown, apical halves sparsely punctate; and T2–T3 basolaterally and T4 entirely with very sparse tomentum and weak apical fringes. They are most similar to L. abanci , which has very sparse basomedial punctation on T2. They are also similar to L. planatum and L. oblongum , both of which have the mesoscutum and mesepisternum dull due to microsculpture.

Male L. subviridatum can be recognised by the following combination: head moderately long (length/width ratio = 1.02); facial tomentum limited to lower paraocular area; flagellomeres long (length/width ratio = 1.80–1.93), bright orange-yellow ventrally; mesoscutum imbricate, punctures sparse between parapsidal lines (i=1–2.5d); mesepisternum rugulose; metapostnotum with coarse rugae reaching posterior margin; propodeum dorsolateral slope rugose; metasomal terga polished, apical halves impunctate (except along premarginal line); and S3–S5 with sparse apicolateral patches of plumose hairs ( Fig. 32 B). They are most similar to L. laevissimum , L. oblongum and L. ephialtum . Male L. laevissimum have denser hairs on metasomal sterna, particularly on S3 ( Fig. 32 A). Male L. oblongum have very coarse rugae on metapostnotum separated by smooth, shining areas distinctly wider than rugae. Male L. ephialtum have sparse basolateral tomentum on metasomal terga.

Range. Saskatchewan east to Ontario, New Hampshire, south to Virginia. USA: CT, IL, IN, MA, MD, NH, NJ, NY, WI, WV, VA. CANADA: ON, SK.

DNA Barcode. Available. Multiple sequences.

Comments. Common. Until recently this species was only known from the type locality (see Wolf & Ascher 2009; Gibbs 2010b). Additional sampling in areas near the type locality are needed to test the limits of the species and to ensure eastern USA material is conspecific. DNA barcodes suggest that there may be a second, closely related species but morphological study has not yet been able to find corroborating characters.

Specimens of L. subviridatum at CUIC were collected from nests in logs.

Figures

FIGURE 32. S 3 (A) with dense pubescence, (B) with sparse pubescence. (From Gibbs 2010 b).