Lasioglossum (Dialictus) sheffieldi 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 : 302-306

Lasioglossum (Dialictus) sheffieldi Gibbs , new species

( Figures 209A–D , 210A–F )

Holotype. ♀ CANADA, Nova Scotia, Kings Co., Avonport , N45.1198 W064.2730, 18.vii.2002 (C. Sheffield); [ PCYU].

Diagnosis. Females of L. sheffieldi can be recognised by the diagnostic combination of a moderately elongate head (length/width ratio = 1.00–1.01), tessellate mesoscutum with punctures dense except on the medial portion ( Fig. 209D ), mesepisternum shining with irregular punctures, metapostnotum with strongly anastomosing rugae, T1 acarinarial fan complete dorsally, metasomal terga polished with faint metallic reflections and moderately dense tomentum on T3–T4. They are most similar to L. yukonae and L. perpunctatum . Female L. yukonae have dense mesoscutal punctures medially and dull mesepisternum with obscure punctures. Female L. perpunctatum have round heads (length/width ratio = 0.95–0.96) and dense mesoscutal punctures medially.

Males of L. sheffieldi can be recognised by the elongate head (length/width ratio = 1.06–1.08), dense facial tomentum limited to lower paraocular area, moderately short flagellomeres (length/width ratio = 1.20– 1.62), mesoscutal punctures moderately sparse on central disc (i=1–3d), mesepisternum with strong punctures, tegula with weak posterior angle, and pale translucent yellow apical impressed areas of the metasomal terga with clear punctures. They are similar to L. perpunctatum which have shorter heads (length/width ratio = 1.00–1.03).

Description. FEMALE. Length 6.20–6.45 mm; head length 1.66–1.72 mm; head width 1.66–1.69 mm; forewing length 4.51–4.58 mm.

Colouration. Head and mesosoma pale blue with green and golden reflections. Clypeus with apical half blackish brown and basal half, and supraclypeal area bronze. Antenna dark brown, flagellum with ventral surface reddish brown. Tegula reddish brown to translucent amber. Wing membrane subhyaline, venation and pterostigma pale amber. Legs brown, medio- and distitarsi reddish. Metasomal terga faintly metallic golden or green, sterna brown, apical margins amber to pale translucent yellow.

Pubescence. Dull white. Moderately dense. 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 sparse, subappressed tomentum, not obscuring surface. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with moderately sparse, fine setae. T1 acarinarial fan dense, complete dorsally. T1 dorsolateral portion with small patch of appressed tomentum. T2 basolaterally and T3–T5 entirely with tomentum. T3–T4 apical margins with very sparse, virtually absent fringes,

Surface sculpture. Face imbricate. Clypeus with apical half polished, weakly lineolate, punctation irregularly spaced (i=1–4d). Supraclypeal area with punctation sparse (i=1–3d). Lower paraocular area punctation dense (i≤d). Antennocular area punctation moderately dense (i=1–1.5d). Upper paraocular area and frons punctate-reticulate. Ocellocular area minutely punctate (i≤d). Gena and postgena polished, weakly lineolate. Mesoscutum tessellate, punctation fine, moderately sparse on centre of disc (i=1–2d), dense laterad and mesad of parapsidal lines (i≤d), and subreticulate on anterolateral portion. Mesoscutellum polished, submedial punctation moderately sparse (i=1–2d). Preëpisternum subreticulate. Hypoepimeral area imbricate, obscurely punctate. Mesepisternum imbricate-punctate (i=1–2d). Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum with strong anastomosing rugae. Propodeum dorsolateral slope, lateral and posterior surfaces imbricate-rugulose. Metasomal terga polished except T1 anterior declivitous surface coriarious, punctation on basal halves moderately dense (i=1–1.5d), sparse on apical halves (i=2–3d).

Structure. Head round (length/width ratio = 1.00–1.01). Eyes convergent below (UOD/LOD ratio = 1.10– 1.13). Clypeus below 2/3 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. Tegula ovoid, somewhat elongate with weak posterior angle ( Fig. 209D ). Inner metatibial spur pectinate with 4–5 teeth. Metapostnotum elongate (MMR ratio = 1.14–1.21), posterior margin weakly 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 5.19– 6.10 mm; head length 1.61–1.63 mm; head width 1.51–1.54 mm; forewing length 3.72–3.97 mm.

Colouration. Head and mesosoma blue. Flagellum with ventral surface reddish brown. Wings hyaline. Tibial bases and medio- and distitarsi reddish brown. Metasoma dark brown; apical margins pale translucent yellow.

Pubescence. Clypeus, and supraclypeal area with sparse tomentum. Lower paraocular area with dense tomentum obscuring surface. Gena with tomentum. T2–T4 basolaterally with very sparse tomentum. S2–S5 apicolaterally with very sparse plumose hairs (1 OD).

Surface sculpture. Mesepisternum polished, punctation distinct. Metapostnotum posterior margin imbricate. Propodeum with lateral surface ruguloso-imbricate.

Structure. Head elongate (length/width ratio = 1.06–1.08). Eyes convergent below (UOD/LOD ratio = 1.27–1.31). Antennal sockets distant (IAD/OAD> 0.9). Pedicel shorter than F1. F2 length 1.5–1.8X F1. F2– F10 moderately short (length/width ratio = 1.20–1.62). Metapostnotum elongate (MMR ratio = 1.04–1.08), posterior margin rounded onto posterior surface.

Terminalia . S7 with median lobe elongate, columnar, apex rounded ( Fig. 210F ). S8 with apicomedial margin weakly convex ( Fig. 210F ). Genitalia as in Fig. 210D–E . Gonobase with ventral arms narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobe elongate, weakly attenuated apically.

Range. Newfoundland, Nova Scotia west to Manitoba,Wisconsin ( Fig. 206 ).

Allotype. CANADA: NOVA SCOTIA: 1♂ topotypical, 20.ix.2001 (C. Sheffield); [ PCYU].

Paratypes. CANADA: NEW BRUNSWICK: 2♀ Tabusintac , 17.vi.1937 (J.W. Cadbury); [ ANSP] ; NEWFOUNDLAND: 2♀ 2♂♂ St. George’s , 5.viii.1979 (P.E. Hallett); [ PHPC] ; NOVA SCOTIA: 1♀ Cape Breton Is., Inverness Dunes , 1.ix.1985 (L. Packer) ; 1♀ topotypical, 29.v.2002 (C. Sheffield); 3♀ topotypical, 13.vi.2002 (C. Sheffield); 1♂ topotypical, 6.vii.2001 (C. Sheffield); 3♀ Kings Co., Avonport , N45.1189 W064.2634, 8.vii.2002 (C. Sheffield & S. Rigby) ; 1♀ topotypical, 1.viii.2001 (C. Sheffield); 2♀ topotypical, 29.v.2002 (C. Sheffield); 1♀ topotypical, 20.vi.2002 (C. Sheffield); 3♀ topotypical, 18.vii.2002 (C. Sheffield); 1♂ topotypical, 20.ix.2001 (C. Sheffield); 2♂♂ topotypical, 9.x.2002 (C. Sheffield); 2♂♂ topotypical, 18.x.2001 (C. Sheffield); 2♂♂ topotypical 18.x.2002 (C. Sheffield); [ PCYU] ; QUEBEC: 1♀ Forestville , 9.viii.1950 ( R. deRuette); [ CNC] ;

Additional material examined. CANADA: MANITOBA: 1♀ Bald Head Hills , 13 mi N Glenboro, 21.vi.1958 (J.F. McAlpine); [ CNC] ; USA: WISCONSIN: 1♀ Manitowac Co., Kingfisher farm (beach); N43.96172 W087.70112, 30.vii.2005 (A. Wolf); [ PCYU] .

Etymology. The species is named for Cory Silas Sheffield who collected most of the type series.

Floral records. BRASSICACEAE : Cakile .

Comments. Uncommon. Specimens were collected in the area of sandy beaches, primarily from Nova Scotia or Southern Newfoundland. A single specimen from the west coast of Lake Michigan and another from a dune system in Manitoba indicate that the species is far more widespread. Populations from unconnected dune systems could be incipient species and warrant additional study.

The presumed sister species, L. yukonae (see below) may also be a sand dune specialist. Another closely related species based on morphology and DNA barcode data is L. marinum (Graenicher) ; a coastal dune specialist on the east coast of the USA. Lasioglossum perdifficile (Cockerell) is also a member of this group but nothing is known about its preferred habitat.

Figures

FIGURE 206. Distribution of Lasioglossum sedi (medium grey), semicaeruleum (light grey), and L. sheffieldi (dark grey and stars).

FIGURE 209. Lasioglossum sheffieldi new species. Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mesoscutum. Scale bars, A–C = 1 mm.

FIGURE 210. Lasioglossum sheffieldi 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.