Lasioglossum (Dialictus) nigroviride (Graenicher)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 203-207

Lasioglossum (Dialictus) nigroviride (Graenicher)

( Figures 151A–D , 152A–E )

Halictus nigro-viridis Graenicher, 1910: 233 . ♀.

Holotype. ♀ USA, Wisconsin, Swiss , Burnett Co., 27.vii.1909, [Milwaukee: 32837]

Halictus (Chloralictus) richardsoni Cockerell, 1937a: 113 . ♀. [new synonymy]

Holotype. ♀ Canada, Alberta, Wabamun , 60 miles E of Edmonton, 1.vii.1935 (E.H. Strickland); [ CNC: 4169]. Examined.

Dialictus nigroviridis Knerer and Atwood, 1962: 169 (Emend.)

Taxonomy. Cockerell, 1937a: Halictus (Chloralictus) nigroviridis , p. 113 (diagnosis); Michener, 1951: Lasioglossum (Chloralictus) nigro-viride , p. 1115, L. (C.) richardsoni , p. 1117 (catalogue); Mitchell, 1960: Dialictus nigro-viridis ♂, p. 406 (redescription); Krombein, 1967: Lasioglossum (Dialictus) nigroviride , p. 464 (catalogue); Hurd, 1979: Dialictus nigroviridis , p. 1968, D. richardsoni , p. 1971 (catalogue); Moure & Hurd, 1987: Dialictus nigroviridis , p. 115, D. richardsoni , p. 127 (catalogue).

Diagnosis. Females of L. nigroviride can be recognised by diagnostic combination of their large size (7.0– 8.1 mm), golden head and mesosoma, gena wider than eye, sparse mesoscutal punctures on central disc (i=1– 4d), distinct, widely spaced mesepisternal punctures (i=1–2.5d) ( Fig. 151D ), moderately strong propodeal carinae and blackish brown metasomal terga that lack any tomentum, fringe hairs and have virtually no fine setae. They are superficially similar to L. obscurum which are smaller (4.9–5.9 mm) and have weak propodeal carinae and sparse but distinct fringe hairs on the metasomal terga.

Males of L. nigroviride can be recognised by their large size (7.0– 7.5 mm), golden green head and mesosoma, elongate flagellomeres (length/width ratio = 1.60–1.87), polished mesoscutum due to weak microsculpture with sparse punctures on central disc (i=1–4d), distinct mesepisternal punctures, blackish brown metasoma and very dense plumose hairs on S3 and apicolateral portions of S4. Male L. obscurum have relatively sparse hairs on the metasomal sterna.

Redescription. FEMALE. Length 7.00– 8.10 mm; head length 1.82–1.99 mm; head width 1.94–2.11 mm; forewing length 5.31–5.92 mm.

Colouration. Head and mesosoma metallic gold with green and bluish reflections. Clypeus with apical 2/3 blackish brown. Antenna blackish brown, flagellum with ventral surface brown. Tegula dark reddish brown. Wing membrane dusky, venation and pterostigma dark amber. Legs dark brown, medio- and distitarsi reddish browm. Metasomal terga blackish brown, terga and sterna with apical margins reddish brown.

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). Face and gena without subappressed hairs. Propodeum with moderately sparse plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with virtually no fine setae. T1 acarinarial fan complete, dorsally very weak. Metasomal terga without appressed tomentum.

Surface sculpture. Face imbricate, punctation fine. Clypeus polished, punctation sparse (i=1–3d). Supraclypeal area with punctation sparse (i=1–3d). Lower paraocular and antennocular areas with punctation sparse (i=0.5–3d). Upper paraocular area punctation dense (i≤d). Frons punctate-reticulate. Ocellocular area distinctly punctate (i=1–2d). Gena and postgena weakly lineolate. Mesoscutum weakly imbricate, polished posteriorly, punctation fine, sparse between parapsidal lines (i=1–4d), moderately dense laterad of parapsidal lines (i=1–2d), contiguous on anterolateral portions. Mesoscutellum similar to mesoscutum, submedial punctation sparse (i=1–4d). Axilla punctate. Metanotum minutely reticulate. Preëpisternum rugulose. Hypoepimeral area weakly imbricate-punctate (i≤d). Mesepisternum weakly imbricate, faintly polished, distinctly punctate (i=1–2.5d). Metepisternum with dorsal half striate, ventral half imbricate. Metapostnotum incompletely rugoso-striate, posterior margin weakly imbricate. Propodeum with dorsolateral slope rugulose, lateral surface ruguloso-imbricate, posterior surface rugulose. Metasomal terga weakly coriarious, punctation on basal halves moderately dense (i=1.5–3), impunctate on apical halves impunctate (except along premarginal line).

Structure. Head wide (length/width ratio = 0.93–0.94). Eyes weakly convergent below (UOD/LOD = 1.08–1.09). Clypeus 1/2 below suborbital tangent, apicolateral margins convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. IOD subequal to OOD. Gena wider than eye. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum posterior margin rounded. Metapostnotum moderately elongate (MMR ratio = 1.29–1.46), posterior margin rounded onto posterior surface. Propodeum with oblique carina strong, lateral carina strong, reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 6.95– 7.50 mm; head length 1.78–1.90 mm; head width 1.75–1.85 mm; forewing length 4.82–5.55 mm

Colouration. Tarsi brownish yellow.

Pubescence. Face with very sparse tomentum. Lower paraocular area with moderately dense tomentum. S2 apical portion with weak subappressed hairs. S3 apical half and S4 lateral portion with dense subappressed plumose hairs (1–2 OD).

Surface sculpture. Mesepisternum distinctly punctate. Metanotum rugose. Propodeum with dorsolateral slope strongly rugose, lateral and posterior surfaces rugulose.

Structure. Head moderately elongate (length/width ratio = 1.01–1.03). Eyes strongly convergent below (UOD/LOD = 1.38–1.40). Clypeus 1/2–2/3 below suborbital tangent, apicolateral margins weakly convergent. Antennal sockets distant (IAD/OAD> 1.2). Frontal line carinate, ending <2 OD below median ocellus. Pedicel less than F1. F2 length 1.8–2.0X F1. F2–F10 moderately elongate (length/width ratio = 1.60–1.87). Metapostnotum moderately elongate (MMR ratio = 1.21–1.38), posterior margin weakly angled onto posterior surface.

Terminalia . S7 with median lobe columnar to weakly clavate, apex rounded ( Fig. 152D ). S8 with apicomedial margin strong convex ( Fig. 152D ). Genitalia as shown in Fig. 152D–E . Gonobase with ventral arms widely separated. Gonostylus small, dorsal setae elongate. Retrorse lobe elongate, weakly attenuated apically.

Range. Nova Scotia west to British Columbia, south to Georgia ( Fig. 150 ).

Additional material examined. CANADA: BRITISH COLUMBIA: 1♀ North Okanagan Reg. Dist., Cherryville, Monashee P.P., Rum Crk. , N50.5099 W118.2785, 1245 m, 20.vii.2008 (L. R. Best); [ PCYU] ; MANITOBA: 2♀ Duck Mt. P.P., Garland R ., 1.vii.1962 (D. Barr); [ ROM] ; NOVA SCOTIA: 2♀ Kings Co., Kentville , N45.0628 W064.4881, 29.v.2001 (C. Sheffield) ; 1♀ Kings Co., Weston, Brooklyn St. , 25.vi.2003 (Jansen, Sheffield & Rigby) ; ONTARIO: 1♀ Wentworth Co., 7.vi.2006, 10:00h–10:30h ( V. MacPhail); [ PCYU] ; USA: MAINE: 1♀ Aroostook Co., Allagash River Waterway , 18.viii.2006 (M.F. Veit) ; MARYLAND: 1♀ Garrett Co., N39.2992 W79.42, 2004 (S.W. Droege) ; MASSACHUSETTS: 1♀ Middlesex Co., Harvard: Oxbow NWR , 28.v.2006 (M.F. Veit); NEW HAMPSHIRE: 1♂ Carroll Co., Effingham, Rt 25 at Ossipee Riv. , 12.viii.2006 (M.F. Veit) ; NEW YORK: 2♀ Steuben Co., N46.3682 W077.3326, 26.vi.2004 (S.W. Droege) ; VERMONT: 2♂♂ Lamoille Co., 4.5 mi NE Hyde Park , 28.vii2006 (M.F. Veit); [ PCYU] ; WISCONSIN: 1♂ Door Co., N45.07475 W87.09224, 2.viii.2005 (C. Destree); [ ARC] .

Floral records. ASTERACEAE : Solidago , Taraxacum , BRASSICACEAE : Barbarea , CORNACEAE : Cornus , FABACEAE : Lupinus polyphyllus , Trifolium , ONAGRACEAE : Epilobium , PLANTAGINACEAE : Plantago , ROSEACEAE: Amelanchier , Aruncus , Fragaria , Malus , Prunus , Rosa , SALICACEAE : Salix .

Comments. Uncommon.

Figures

FIGURE 150. Distribution of Lasioglossum nevadense (dark grey) and L. nigroviride (light grey).

FIGURE 151. Lasioglossum nigroviride (Graenicher). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mesepisternum. Scale bars, A–C = 1 mm.

FIGURE 152. Lasioglossum nigroviride (Graenicher). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) ventral view of genital capsule, S7, S8; (E) dorsal view of genital capsule. Scale bars, A–C = 1 mm, E = 0.5 mm.