Lasioglossum (Dialictus) dreisbachi (Mitchell)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 110-112

Lasioglossum (Dialictus) dreisbachi (Mitchell)

( Figures 97A–D , 98A–H )

Dialictus dreisbachi Mitchell, 1960: 391 . ♀ ♂. Holotype. ♀ USA, Michigan, Clare Co., 24.v. 1958 (R. & K. Dreisbach); [NCSU]. Examined.

Taxonomy. Lasioglossum (Dialictus) dreisbachi Krombein, 1967: 463 (catalogue); Hurd, 1979: Dialictus dreisbachi , p. 1966 (catalogue); Moure & Hurd, 1987: Dialictus dreisbachi , p. 99 (catalogue).

Diagnosis. Both sexes of L. dreisbachi are recognisable by the sharp delineation between the coarsely rugose dorsal mesepisternum and the densely tessellate-punctate ventral mesepisternum ( Fig. 97D ). Females share characters typical of the L. viridatum species-group such as clypeus apicolateral margin convergent, mesoscutal punctation moderately sparse medially, T1 acarinarial fan incomplete dorsally, T2–T5 with sparse tomentum and T2 apical half virtually impunctate (except along premarginal line).

Redescription. FEMALE. Length 5.06–5.43 mm; head length 1.49–1.52 mm; head width 1.54–1.58 mm; forewing length 4.27–4.39 mm.

Colouration. Head and mesosoma blue or greenish blue. Clypeus distal half blackish brown. Supraclypeal area greenish blue, sometimes with brassy reflections. Antenna blackish brown, flagellum with ventral surface reddish brown to orange. Tegula dark reddish brown. Wing membrane subhyaline, venation and pterostigma amber. Legs brown, medio- and distitarsi reddish brown. Metasoma blackish brown, terga and sterna with apical margins reddish.

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). Paraocular area with sparse subappressed hairs. Gena without 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 of appressed hairs with wide dorsal opening. T2–T3 basolaterally and T4–T5 entirely with sparse, scattered tomentum. T2 apicolateral and T3–T4 apical margins with very sparse bands.

Surface sculpture. Face imbricate, punctation fine, shallow. Clypeus with apical half polished, punctation moderately 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 dense (i=1–1.5d). Upper paraocular area and frons punctate-reticulate. Ocellocular area obscurely punctate (i=d). Gena lineolate. Postgena imbricate. Mesoscutum tessellate-imbricate, with a polished longitudinal area halfway between midline and parapsidal line, punctation fine, moderately sparse between parapsidal lines (i=1–2d), dense laterad of parapsidal line (i≤d), contiguous on anterolateral portion. Mesoscutellum similar to mesoscutum, punctation sparse (i=2–5d). Axilla minutely punctate. Metanotum imbricate. Preëpisternum rugose. Hypoepimeral area rugulose. Mesepisternum dorsal half coarsely rugose, ventral half densely tessellate-imbricate with moderately strong punctation (i=1–1.5d), dorsal and ventral halves of mesepisternum sharply delineated by change in sculpture. Metepisternum with dorsal half strongly striate, ventral half ruguloso-imbricate. Metapostnotum incompletely striate, interstices wide, posterior margin imbricate. Propodeum with dorsolateral slope rugose, lateral surface imbricate, posterior surface tessellate. Metasomal terga weakly coriarious, punctation on basal halves moderately dense (i=1.5d), extremely sparse on apical halves (i=3–6d).

Structure. Head wide (length/width ratio = 0.96–0.97). Eyes convergent below (UOD /LOD ratio = 1.18– 1.22). Clypeus 2/3 below suborbital line, anterolateral margins convergent. Antennal sockets close (IAD/ OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. Gnea narrower than eye. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum moderately elongate (MMR ratio = 1.20–1.32), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina virtually absent, lateral carina moderately strong, reaching 2/3 of the distance to dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.76– 5.12 mm; head length 1.49–1.51 mm; head width 1.49–1.51 mm; forewing length 4.09–4.21 mm.

Colouration. Flagellum with ventral surface orange-yellow. Medio- and distitarsi reddish brown.

Pubescence. Lower face with sparse tomentum, partially obscuring surface except lower paraocular area with dense tomentum obscuring surface. S3–S4 apicolateral portions with posteromedially directed hair tufts.

Surface sculpture. Metepisternum with dorsal half strongly rugose. Metapostnotum coarsely rugoso-striate. Propodeum dorsolateral slope, lateral and posterior surfaces strongly rugose. Metasomal terga punctation on basal halves close (i=2d), apical half impunctate (except along premarginal line).

Structure. Head moderately wide to round (length/width ratio = 0.98–1.00). Eyes strongly convergent below (UOD /LOD ratio = 1.44–1.48). Antennal sockets distant (IAD/OAD> 1.4. Pedicel shorter than F1. F2 length 2X F1. F2–F10 (length/width ratio = 1.86–2.00). Metapostnotum moderately elongate (MMR ratio = 1.23–1.32), posterior margin sharply angled onto posterior surface.

Terminalia . S7 median lobe wide, columnar, apex rounded ( Fig. 98G ). S8 apical margin weakly convex ( Fig. 98G ). Genitalia as in Fig. E–F, H. Gonobase with ventral arms narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobes elongate, attenuated apically ( Fig. 98H ).

Range. Ontario, west to Alberta, Wisconsin and southeast to Maryland ( Fig. 99 ).

Additional material examined. CANADA: ALBERTA: 1♂ Edmonton , 22.viii.1984 (Thormin, Spanton, Nicholson); [ PMAE] ; ONTARIO: 1♀ Algonquin P.P., by Crossbar Lake , 17 T 0711719 E 5022831N, 12– 27.v.2007 (E. Proctor); 1♀ Brock , 9.ix.2003 [ PCYU] ; 1♀ Iona , 25.v.1962 (G. Knerer); [ ROM] ; 1♀ Toronto , 16.vii.1991 [ CNC] ; 3♀ Wentworth Co., 7.vi.2006 ( V. MacPhail); [ PCYU] ; USA: MICHIGAN: 1♂ allotype, Cheboygen Co., 18.viii.1957 ( R. R. Dreisbach); [ NCSU] ; WISCONSIN: 1♀ Brown Co., 3489 Yorkshire Dr. , N44.54415 W087.90710, 25.v.2005 (A. Wolf); [ PCYU] .

Floral records. SALICACEAE : Salix .

Comments. Rare. This species belongs to the L. viridatum species-group.

Figures

FIGURE 97. Lasioglossum dreisbachi (Mitchell). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mesepisternum. Scale bars, A–C = 1 mm.

FIGURE 98. Lasioglossum dreisbachi (Mitchell). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mesepisternum; (E) ventral view of genital capsule; (F) dorsal view of genital capsule; (F) S7, S8; (H) apical view of genital capsule. Scale bars, A–C = 1 mm, H = 0.5 mm.

FIGURE 99. Distribution of Lasioglossum dreisbachi (light grey), and L. dubitatum (dark grey).