Lasioglossum (Dialictus) subviridatum (Cockerell)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 313-317

Lasioglossum (Dialictus) subviridatum (Cockerell)

( Figures 215A–C , 216A–F )

Halictus (Chloralictus) subviridatus Cockerell, 1938a: 2 . ♀ ♂. Holotype. ♀ CANADA, Lake Ajawaan , Saskatchewan, 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).

Diagnosis. Females of L. subviridatum can be recognised by the diagnostic combination of a wide head (length/width ratio = 0.93–0.96), polished mesoscutum due to weak microsculpture with moderately sparse punctures on the central disc (i=1–2.5d), brownish yellow tegula, weakly rugulose mesepisternum that is moderately shiny, strongly rugoso-striate metapostnotum, very weak T1 acarinarial fan with very wide dorsal opening, metasomal terga brown, polished due to weak microsculpture, apical halves sparsely punctate, T2– T3 basolaterally and T4 entirely with very sparse tomentum and weak apical fringes. They are similar to L. planatum and L. oblongum which both have the mesoscutum and mesepisternum dull due to microsculpture.

Males of L. subviridatum can be recognised by the moderately elongate head (length/width ratio = 1.02), facial tomentum limited to lower paraocular area, elongate flagellomeres (length/width ratio = 1.80–1.93) that are bright orange-yellow on ventral surface, central disc of mesoscutum imbricate with sparse punctures (i=1– 2.5d), rugulose mesepisternum, metapostnotum with coarse rugae reaching posterior margin, propodeum dorsolateral slope rugose, polished metasomal terga with apical halves impunctate (except along premarginal line), and weak apicolateral patches of plumose hairs on S3–S5 ( Fig. 51B ). They are most similar to L. laevissimum , L. oblongum and L. ephialtum . Male L. laevissimum have denser hairs on the metasomal sterna particularly on S3 ( Fig. 51A ). Male L. oblongum have very coarse rugae on the metapostnotum separate by smooth shining areas distinctly wider than the rugae ( Fig. 48A ). Male L. ephialtum have sparse basolateral tomentum on the metasomal terga.

Redescription. FEMALE. Length 4.45–6.10 mm; head length 1.46–1.66 mm; head width 1.54–1.78 mm; forewing length 4.09–4.64 mm.

Colouration. Head and mesosoma bluish green with golden reflections. Clypeus with apical half blackish brown and basal half, and supraclypeal area greenish. Antenna dark brown, flagellum with ventral surface dark brown to reddish brown. Tegula translucent reddish brown. Wing membrane subhyaline, venation and pterostigma dark amber. Legs dark brown; medio- and distitarsi ferruginous. Metasoma blackish brown, terga and sterna with apical margins reddish to brownish yellow.

Pubescence. Dull white. Very sparse. Head and mesosoma with moderately dense woolly hairs (1–1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Lower paraocular area and gena without subappressed tomentum. Propodeum with dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with sparse, fine setae. T1 acarinarial fan with dorsal opening. T2–T3 basolaterally and T4 entirely with sparse tomentum. T2 apicolateral and T3–T4 apical margins with very sparse apical fringes, virtually absent.

Surface sculpture. Face imbricate, punctation fine. Clypeus polished, basal margin weakly imbricate, punctation sparse (i=1–3d). Supraclypeal area with punctation moderately sparse (i=1–2.5d). Lower paraocular area punctation dense (i≤d). Antennocular area punctation moderately sparse (i=1–2d). Upper paraocular area and frons reticulate-punctate. Ocellocular area punctation obscure (i=1–1.5d). Gena weakly lineolate. Postgena weakly imbricate. Mesoscutum polished, weakly imbricate-tessellate, punctation fine, moderately sparse between parapsidal lines (i=1–2.5d), dense laterad of parapsidal lines (i≤d), contiguous on anterolateral portions. Mesoscutellum polished, submedial punctation sparse (i=2–5d). Axilla punctate. Metanotum ruguloso-imbricate. Preëpisternum rugose. Hypoepimeral area imbricate. Mesepisternum dorsal half weakly rugose, obscurely punctate, ventral half rugulose. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum rugoso-striate. Propodeum with dorsolateral slope rugulose, lateral surface ruguloso-tessellate, posterior surface imbricate. Metasomal terga polished except weakly coriarious on apical margins, punctation on basal halves (i=1–2d), sparse and irregularly spaced on apical halves (i=2–4d).

Structure. Head wide (length/width ratio = 0.93–0.96). Eyes convergent below (UOD/LOD ratio = 1.18– 1.21). Clypeus 1/2–2/3 below suborbital tangent, apicolateral margins convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2.5 OD below median ocellus. Gena narrower than eye. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum moderately elongate (MMR ratio = 1.20–1.29), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina very weak, lateral carina weak, not reaching dorsal surface.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length. 6.34 mm; head length. 1.61 mm; head width. 1.58 mm; forewing length. 4.51 mm.

Colouration. Head blackish blue. Mesosoma golden green except propodeum bluish. Flagellum with ventral surface bright orange-yellow. Pterostigma reddish brown. Tarsi yellowish brown.

Pubescence. Lower paraocular area width moderately dense tomentum partially obscuring surface. Gena without evident tomentum. S3–S5 with moderately dense patches of plumose hairs (1 OD).

Surface sculpture. Mesoscutum imbricate on medial portion. Metanotum rugose. Mesepisternum rugulose. Propodeum with dorsolateral slope rugose, lateral surface rugulose, posterior surface rugose. Metasomal terga polished except apical halves impunctate (except along premarginal line).

Structure. Head moderately elongate (length/width ratio = 1.02). Eyes strongly convergent below (UOD/ LOD ratio = 1.46). Clypeus 1/2 below suborbital tangent, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD> 1.2). Frontal line carinate, ending 2 OD below median ocellus. Pedicel shorter than F1. F2 length 1.8X F1. F2–F10 elongate (length/width ratio = 1.80–1.93). Metapostnotum with dorsal surface moderately short (MMR ratio = 1.30), posterior margin weakly angled onto posterior surface.

Terminalia . S7 with median lobe elongate, weakly clavate, apex weakly rounded ( Fig. 216F ). S8 with apicomedial margin weakly convex ( Fig. 216F ). Genitalia as in Fig. 216D–E . Gonobase with ventral arms narrowly separated. Gonostylus small. Retrorse lobe elongate, strongly attenuated apically.

Range. Saskatchewan east to Ontario, New Hampshire, south to Virginia ( Fig. 212 ).

Additional material examined. CANADA: ONTARIO: 1♀ Halton Co., Hilton Falls, 20.iv.1980 (P.E. Hallet); [ PHPC]; 1♀ Lambton Co. , N43°16.88´W081°48.474´, 15.vii.2008 (A. Taylor); [ PCYU] ; USA: CON- NECTICUT: 2♀ New London Co., Montville Rt. 82/ South, N41°30.680´W072°10.816´, 19.vii.2006

(Bricker & Watson); INDIANA: 1♀ Jasper Co., Tefft Savanna, N41°9´34´´ W086°58´39´´, 28.iv.2004 ( R. Grundel); 1♀ Vigo Co. , Kieweg, 13.iv.2000 ( R. P. Jean); MARYLAND: 1♀ Anne Arundel Co. , N38.891 W076.5301, 13.iv.2003 (S.W. Droege); 1♀ Patuxent Wildlife ..., N39 W076.7, 26–27.v.2002 (H.W. Ikerd); 1♀ Pr. George’s Co. , N38.8987 W076.6783, 7.vii.2001 (S.W. Droege); 2♀ Pr. George’s Co. , N38.9892 W076.9306, 15–16.vii.2003 (J. Loutsch); 1♀ Pr. George’s Co. , N38.9096 W076.6842, 15.vii; NEW HAMP- SHIRE : 1♀ Coos Co., 4.8 mi W of Twin Mountain, Bethlehem, 23.vi.2006 (M.F. Veit); [ PCYU]; NEW YORK: 1♀ Wayne Co. , Endress , Sodus Pt., 19.v.2009 (M.C. Orr); WEST VIRGINIA: 1♀ Hampshire Co., N39.2479 W078.5267, 6–8.viii.2006 (Students); WISCONSIN: 1♀ Grant Co. and lower WI River Wildlife Area , N43.00306 W091.02618, 1.vii.2005 (A. Wolf); VIRGINIA: 1♀ Fairfax Co. , N38.967 W077.1687, 11– 12.iv.2005 (B. Steury); [ PCYU] .

Floral records. ASTERACEAE : Solidago , PORTULACACEAE : Claytonia virginica .

Comments. Common.

Figures

FIGURE 48. Metapostnotum of male (A) L. oblongum, (B) L. laevissimum.

FIGURE 51. Sternal hairs of male Dialictus (A) dense, (B) sparse.

FIGURE 212. Distribution of Lasioglossum sitocleptum (black), L. subversans (light grey), and L. subviridatum (dark grey).

FIGURE 215. Lasioglossum subviridatum (Cockerell). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 216. Lasioglossum subviridatum (Cockerell). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) ventral view of genital capsule; (E) dorsal view of genital capsule; (F) S7, S8. Scale bars, A–C = 1 mm, F = 0.5 mm.