Lasioglossum (Dialictus) ephialtum Gibbs, 2010

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 124-129

Lasioglossum (Dialictus) ephialtum Gibbs , new species

( Figures 106A–D , 107A–F )

Holotype. ♀ CANADA, Ontario, Toronto , Brunswick Ave., N43.66165 W079.40571, 6.x.2006 (J. Gibbs); [ PCYU].

Diagnosis. Females of L. ephialtum can be recognised by the diagnostic combination of a moderately wideface (length/width ratio = 0.95–0.99), mesoscutum imbricate with distinctly separated punctures between parapsidal lines (i=1–2d), rugulose-imbricate mesepisternum, metapostnotum with rugae reaching, or nearly reaching, the posterior margin which is angled on to the posterior surface of propodeum, brown metasomal terga polished due to weak microsculpture, T1 acarinarial fan strong with dorsal opening, T2–T4 basolaterally with moderately dense tomentum, and T3–T4 with moderately strong apical fringes. They are similar to those of L. pacatum , L. planatum , and L. taylorae which all have less complete metapostnotal rugae and less abundant pubescence on the metasomal terga. Female L. ephialtum are most similar to L. sablense females which have the mesoscutum polished and weakly metallic metasomal terga. The rugulose mesepisternum of this species distinguishes it from L. viridatum and L. dreisbachi .

Males are similar to females but may be distinguished by their elongate flagellomeres (length/width ratio = 1.80–1.85), mesoscutum weakly imbricate, brownish yellow tarsi, metasomal terga impunctate on apical halves, T2–T4 basolaterally with sparse tomentum, moderately dense tomentum on the apicolateral portions of S3–S5, and strongly rugose metapostnotum. They are similar to L. laevissimum , L. mitchelli and L. sablense . Male L. laevissimum lack tomentum on the metasomal terga and have obscure punctures on the ventral 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. Male L. sablense have shorter flagellomeres (length/width ratio = 1.57–1.67) and a highly polished mesoscutum due to lack of microsculpture.

Description. FEMALE. Length 4.94–6.10 mm; head length 1.34–1.58 mm; head width 1.42–1.61 mm; forewing length 3.42–4.09 mm.

Colouration. Head and mesosoma pale golden green or bluish green. Clypeus basally and supraclypeal area golden. Antenna dark brown, flagellum with ventral surface reddish brown, F8–F10 sometimes with ventral surface orange-yellow. Tegula dark reddish brown to translucent brownish yellow. Wing membrane subhyaline, venation and pterostigma pale brownish yellow. Legs brown, medio- and distitarsi reddish brown. Metasoma dark brown, terga and sterna with apical margins translucent brownish yellow.

Pubescence. Dull white. Moderately 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 with virtually no tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with sparse, fine setae. T1 acarinarial fan strong with narrow dorsal opening, less than width of lateral hair patches. T2–T3 basolateral portions and T4 with tomentum partially obscuring surface. T2 apicolateral and T3–T4 apical margins with moderately strong fringes.

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

Structure. Head wide to elongate (length/width ratio = 0.95–0.99). Eyes convergent below (UOD/LOD ratio = 1.17–1.20). Clypeus 2/3 below suborbital tangent, apicolateral margins convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. Gena narrower than eye. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum moderately elongate (MMR ratio = 1.21–1.33), posterior margin sharply angled onto posterior surface. Propodeum with oblique carina very weak, lateral carina weak, not reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.51– 6.04 mm; head length 1.37–1.61 mm; head width 1.34–1.54 mm; forewing length 3.23–4.09 mm.

Colouration. Flagellum with ventral surface reddish brown to brownish yellow. Pterostigma reddish brown. Tibial apices, metatibial base and tarsi yellowish brown.

Pubescence. Face below eye emargination with moderately sparse tomentum, partially obscuring surface except lower paraocular area with dense tomentum obscuring surface. Gena with sparse tomentum. T2–T4 basolaterally with sparse tomentum. S3–S5 apicolateral portions with moderately dense plumose hairs (1 OD).

Surface sculpture. Metanotum rugose. Preëpisternum and hypoepimeral area rugose. Mesepisternum with dorsal portion rugose and ventral portion ruguloso-imbricate. Metepisternum with dorsal two-thirds rugosostriate. Metapostnotum coarsely rugose. Propodeum dorsolateral slope rugose, lateral surface rugoso-imbricate, posterior surface rugose. Metasomal terga with apical halves impunctate (except along premarginal line).

Structure. Head elongate (length/width ratio = 1.02–1.10). Eyes strongly convergent below (UOD/LOD ratio = 1.52–1.54). Labrum not emarginate. Antennal sockets moderately distant (IAD/OAD> 1.4). Frontal line carinate, ending 2 OD below median ocellus. IOD subequal to OOD. Pedicel shorter than F1. F2 length 1.8–2.0X F1. F2–F10 elongate (length/width ratio = 1.80–1.85). Metapostnotum moderately elongate (MMR ratio = 1.17–1.18), posterior margin sharply angled onto posterior surface.

Terminalia . S7 with median lobe columnar, apex rounded ( Fig. 107F ). S8 with apicomedial margin weakly convex ( Fig. 107F ). Genitalia as in Fig. 107D–E . Gonobase with ventral arms narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobes narrow, attenuated and recurved apically.

Range. Ontario south to West Virginia, west to Colorado ( Fig. 108 ).

Allotype. CANADA: 1♂ topotypical, 6.x.2006 (J. Gibbs); [ PCYU]

Paratypes. CANADA: NEW BRUNSWICK: 1♀ Kouchibouguac N.P., 12.viii.1977 (S.J. Miller); [ CNC] ; NOVA SCOTIA: 1♀ Kings Co., Avonport , N45.1198 W064.273, 6.vi.2002 (C. Sheffield) ; ONTARIO: 1♀ Lambton , N43°13.981´W081°51.9´, 6.vi.2007 (A. Taylor) ; 1♀ Lambton , N43°15.626´W081°49.368´, 10.viii.2007 (A. Taylor) ; 5♀♀ QUBS , 17.vii.2006 (L. Packer); 4♀♀ QUBS , viii.2006 (L. Packer); 2♀♀ Toronto, Ulster St. , N43.65898 W079.41332, x.2006 (J. Gibbs) ; 2♂ Toronto, Ulster St. , N43.659 W079.413, 23.ix.2006 (J. Gibbs) ; 1♀ York University, Keele Campus, Boyer woodlot, 28.vii.2005 (E. Willis) ; 2♀♀ York University , Keele Campus, CSEB greenroof, 20.vi.2005 (E. Willis); 1♀ York University , Keele Campus, CSEB greenroof, 28.vii.2005 (E. Willis); 1♀ York University , Keele Campus, CSEB greenroof, 4.viii.2006 (E. Willis); 1♀ York University, Keele Campus, grass near Boyer woodlot, 20.vi.2005 (E. Willis) ; 1♀ York University, Keele Campus, Pond Rd. greenroof, 28.vii.2005 (E. Willis) ; 1♀ York University , N43.772 W079.497, 24.v.2006 (J. Gibbs) ; 1♀ York University , N43.77175 W079.4965, 20.iv.2006 (J. Gibbs); [ PCYU] ; USA: COLORADO: 1♀ Larimer Co., N40.6833 W105.3975, 11–12.v.2004 (S.W. Droege) ; DISTRICT OF COLUMBIA: 1♂ N38.8871 W077.012, 8.vii.2005 (N.B. Staff) ; 6♀♀ N38.9309 W077.116, 24.vi.2006 (Pascarella); 1♂ Mall , N38.8912 W077.0242, 16.viii.2006 (S.W. Droege) ; 1♂ Washington , N38.887 W077.045, 15–16.vii.2004 (C. Osborn) ; INDIANA: 1♀ Lake Co., Indiana Dunes N.L., Marquette Tr. , N41°36´40´´ W87°14´14´´, 7.vii.2004 ( R. Grundel) ; 1♀ Porter Co., Indiana Dunes N.L., Ogden Dunes , N41°36´5 [?]´´ W087°12´12´´, 4.v.2004 ( R. Grundel) ; IOWA: 1♀ Dickinson Co., 4.2 km NW Spirit Lake , N43°26´20´´ W095°10´54´´, 20.v.2004 (C. Hemsley) ; 1♀ Hamilton Co., 0.8 km E Blairsburg , N42°28´57´´ W093°37´26´´, 18.v.2004 (C. Hemsley) ; MARYLAND: 2♀ Montgomery Co., N38.97 W077.1565, 24.vi.2006 (S.W. Droege); [ PCYU] ; MINNESOTA: 1♀ Douglas Co., N45.79755 W095.73211, 17.viii.2004 (S. Pimm & S. Wagenius) ; 2♀ Plymouth , vi.2005 (L. Packer) ; NEW HAMPSHIRE: 1♀ Moosebrook S.P., 27.vii.1978 (P.E. Hallet); [ PHPC] ; NEW YORK: 1♀ Queens Co., Floral Pk., Long Is. , 17.vii.1983 (D. Yanega); [ UCR]; PENN- SYLVANIA: 1♀ Philadelphia Co., N39.9628 W075.1773, 23.viii.2005 (S.W. Droege) ; WEST VIRGINIA: 1♀ Berkelye Co., N39.5187 W077.8412, 7–8.v.2005 (S.W. Droege) ; 1♀ Hampshire Co., N39.21645 W078.7483, 11.vii.2005 (S.W. Droege) ; 1♂ Hampshire Co., N39.4667 W078.545, 7.vii.2002 (S.W. Droege) ; 2♀ near Charleston , N38.41211 W081.64776, 15.viii.2006 (J. Gibbs) ; WISCONSIN: 1♀ 1♂ Iowa Co., Avoca Prairie , N43.19501 W090.28733, 23.vii.2006 (A. Wolf); [ PCYU] .

Etymology. The specific epithet is derived from the Greek “efialtis” meaning “nightmare”.

Comments. Common. This species is part of the L. viridatum species-group and has likely caused a great deal of confusion in Dialictus identifications in the Eastern USA due to its close similarity to other species in this group and a lack of a single diagnostic morphological character. It keys out near L. admirandum using Mitchell (1960). Lasioglossum ephialtum was referred to as “A-3” by George Eickwort who also recognised it as distinct. This species displays some morphological variability and could be a repository for additional cryptic species.

Figures

FIGURE 106. Lasioglossum ephialtum new species. Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) T1, T2. Scale bars, A–C = 1 mm.

FIGURE 107. Lasioglossum ephialtum new species. 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.

FIGURE 108. Distribution of Lasioglossum ephialtum (light grey) and L. fattigi (dark grey).