Lasioglossum (Dialictus) pacatum (Sandhouse)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 228-230

Lasioglossum (Dialictus) pacatum (Sandhouse)

( Figure 166A–D )

Halictus (Chloralictus) pacatus Sandhouse, 1924: 16 . ♀. Holotype. ♀ USA, Colorado, Peaceful Valley , 1919, (Cockerell), [NMNH: 26407]. Examined.

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) pacatum , p. 1116 (catalogue); Hurd, 1979: Dialictus pacatus , p. 1969 (catalogue); Moure & Hurd, 1987: Dialictus pacatus , p. 119 (catalogue).

Diagnosis. Females of L. pacatum can be recognised by the diagnostic combination of a relatively large size (5.1–6.4 mm), green head and mesosoma, round to relatively elongate head (length/width ratio = 0.96– 1.01), lower face distinctly smooth, gena narrower than eye, mesoscutal punctures moderately sparse on central disc (i=1–2d), rugulose mesepisternum, metapostnotum with longitudinal rugae not reaching posterior margin, propodeum oblique carina virtually absent, dark brown metasomal terga polished due to lack of microsculpture, T1 acarinarial fan strong but with dorsal opening, T2 basolaterally and T3–T5 entirely with moderately dense tomentum, and T3–T4 with weak apical fringes. They are similar to L. laevissimum , L. marinense , L. ephialtum and L. viridatulum (Cockerell) . Female L. laevissimum have a wide head (length/ width ratio = 0.89–0.95) and a gena wider than the eye. Female L. marinense have virtually no tomentum on the metasomal terga and a very weak T1 acarinarial fan that is present only as two small lateral hair patches. Female L. ephialtum have the metapostnotum completely rugoso-striate and moderately strong fringes on the metasomal terga. Female L. viridatulum have the lower portion of the face less smooth with distinct lines on the apical half of the clypeus.

Male unknown.

Redescription. FEMALE. Length 5.06–6.35 mm; head length 1.54–1.75 mm; head width 1.52–1.78 mm; forewing length 3.97–4.70 mm.

Colouration. Head and mesosoma greenish blue. Clypeus with apical half blackish brown and basal half, and supraclypeal area more greenish or bronze. Antenna dark brown, flagellum with ventral surface orangebrownish yellow. Tegula reddish brown. Wing membrane subhyaline, venation and pterostigma amber. Legs brown, medio- and distitarsi and sometimes metabasitarsus base brownish yellow. Metasomal blackish brown, terga and sterna with apical margins reddish brown.

Pubescence. Dull white. 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 moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with moderately sparse, fine setae. T1 acarinarial fan incomplete, dorsal open ing equal in width to lateral appressed hairs. T2 basal portion and T3 basal margin with appressed tomentum. T4 with sparse tomentum partially obscuring surface. T2 apicolateral and T3–T4 apical margins with sparse fringes.

Surface sculpture. Face imbricate, punctation moderately fine. Clypeus with apical half polished, punctation unevenly spaced (i=1–3d). Supraclypeal area with punctation moderately sparse (i=1–2d). 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 imbricate, punctation moderately fine, moderately sparse between parapsidal lines (i=1–2d), dense laterad of parapsidal lines (i≤d), contiguous on anterolateral portions (i≤d). Mesoscutellum similar to mesoscutum, submedial punctation moderately sparse (i=1.5–2.5d). Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate. Mesepisternum dorsal half weakly rugulose, ventral half imbricate. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum incompletely rugoso-striate, posterior margin imbricate. Propodeum with dorsolateral slope rugulose, lateral surface imbricate-rugulose, posterior surface imbricate. Metasomal terga weakly coriarious, punctation on basal halves moderately sparse (i=1–3d), apical half impunctate except along premarginal line and a few scattered punctures on marginal zone.

Structure. Head wide to round (length/width ratio = 0.96–1.01). Eyes convergent below (UOD/LOD ratio = 1.18–1.22). Clypeus 2/3 below suborbital tangent, apicolateral margins strongly 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 3–5 teeth. Metapostnotum moderately elongate (MMR ratio = 1.19– 1.33), posterior margin rounded onto posterior surface. Propodeum with oblique carina obscure, lateral carina short, not reaching dorsal margin.

MALE. Unknown.

Range. Colorado to British Columbia ( Fig. 165 ).

Additional material examined. CANADA: BRITISH COLUMBIA: 1♀ Abbotsford , N49°07´41´´ W122°25´05´´ 13.v.2003 (C. Ratti) ; 1♀ Abbotsford , N49°07´41´´ W122°25´05´´ 16.v.2003 (C. Ratti) ; 1♀ Abbotsford , N49°07´41´´ W122°25´05´´ 25.v.2003 (C. Ratti) ; 1♀ Abbotsford , N49°07´41´´ W122°25´05´´ 31.v.2003 (C. Ratti); [ PCYU] ; 1♀ Aldergrove , 50–100 m, 3.vii.1978 (N.L.H. Krauss); [ AMNH] ; 1♀ Cowichan River P.P, 10 km E Lake Cowichan, N48°46´39´´ W123°56´30.2´´ 11.v.2005, wpt (E. Elle) ; 1♀ Fort Langley , N49°09´27´´ W122°29´56´´ 18.vi.2004 (C. Ratti) ; 1♀ Mission , N49°12´36´´ W122°14´46´´ 19.v.2003 (C. Ratti) ; 2♀ Mission , N49°12´36´´ W122°14´46´´ 22.v.2003 (C. Ratti) ; 1♀ Pitt Meadows , N49°14´59´´ W122°43´02´´ 5.vii.2003 (C. Ratti) ; 1♀ Richmond , N49°08´41´´ W123°04´24´´ 9.iv.2004 (C. Ratti) ; 1♀ Richmond , N49°08´41´´ W123°04´24´´ 14.v.2003 (C. Ratti) ; 1♀ Surrey , N49°05´54´´ W122°47´31´´ 4.v.2003 (C. Ratti) ; 2♀ Surrey , N49°05´54´´ W122°47´31´´ 14.v.2003 (C. Ratti) ; 1♀ Surrey , N49°05´54´´ W122°47´31´´ 20.v.2003 (C. Ratti) ; 1♀ Westham Island , N49°05´18´´ W123°09´50´´ 12.v.2003 (C. Ratti); [ PCYU] ; USA: COLORADO: 1♀ Gilpin Co., HWY 19, N39.87015 W105.46551, 2–31.viii.2007, (Gibbs & Sheffield); [ PCYU] .

Comments. Common. This species is part of the L. viridatum species-group and is very similar to L. viridatulum . Both were originally described from Colorado. Additional study is needed to determine if these names are synonymous.

Figures

FIGURE 165. Distribution of Lasioglossum oceanicum (light grey), L. pacatum (medium grey), and L. packeri (dark grey).

FIGURE 166. Lasioglossum pacatum (Sandhouse). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.