Lasioglossum (Dialictus) occidentale (Crawford)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 220-223

Lasioglossum (Dialictus) occidentale (Crawford)

( Figures 161A–E , 162A–F )

Dialictus occidentalis Crawford 1902: 318 . ♀.

Holotype. ♀ USA, New Mexico, Las Vegas, 4.vii., (Cockerell), [ NMNH: 3406]. Examined

Dialictus Theodori Crawford 1902: 318 . ♀. [new synonymy].

Holotype. ♀ USA, New Mexico, Las Vegas , 29.v.1902, on Convolvulus incanus (P. Hitchcock) ; [ ANSP: 10091]. Examined.

Halictus galei Cockerell 1919: 272 . ♀.

Holotype. ♀ USA, Colorado, Gold Hill , Colorado, 12.vii.1919, ( T. & W. Cockerell), [ NMNH: 40261]. Examined.

Taxonomy. Cockerell 1901: Halictus anomalus , ♀ (misdet), p. 126 (description); Michener, 1951: Lasioglossum (Dialictus) occidentale , p. 1115, L. (D.) theodori , p. 1119 (catalogue); Hurd, 1979: Dialictus occidentale , p. 1969, D. theodori , p. 1972 (catalogue); Moure & Hurd, 1987: Dialictus occidentalis , p. 117, D. theodori , p. 135 (catalogue).

Diagnosis. See diagnosis for L. anomalum .

Redescription. FEMALE. Length 4.15–5.73 mm; head length 1.39–1.49 mm; head width 1.32–1.49 mm; forewing length 3.42–3.60 mm.

Colouration. Head and mesosoma greenish blue. Clypeus with apical half blackish brown and basal half, and supraclypeal area more green or bronze. Antenna dark brown, flagellum with ventral surface reddish brown. Tegula brown. Wing membrane subhyaline, venation and pterostigma pale amber. Legs brown, medio- and distitarsi reddish brown. Metasomal terga brown, terga and sterna posterior margins 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 below. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with moderately dense, fine setae. T1 acarinarial fan complete but sparse dorsally. T2 basolaterally and T3–T5 entirely with moderately dense tomentum partially obscuring surface. T2 apicolateral and T3–T4 apical margins with sparse fringes.

Surface sculpture. Face imbricate, punctation moderately strong. Clypeus with apical half polished, punctation sparse (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 densely punctate (i≤d). Gena weakly lineolate. Postgena imbricate. Mesoscutum imbricate, punctation moderately fine, moderately dense between parapsidal lines (i=0.5– 1.5d), dense mesad and laterad of parapsidal lines (i≤d), contiguous on anterolateral portions. Mesoscutellum polished, submedial punctation moderately sparse (i=1–2.5d). Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area rugulose. Mesepisternum ruguloso-punctate (i≤d). Metepisternum with dorsal third striate, ventral portion ruguloso-imbricate. Metapostnotum incompletely rugoso-striate, posterior margin imbricate. Propodeum with dorsolateral slope imbricate, lateral surface ruguloso-imbricate, posterior surface imbricate. Metasomal terga polished, punctation moderately dense throughout (i=1–2.5d).

Structure. Head moderately elongate (length/width ratio = 1.00–1.05). Eyes convergent below (UOD/ LOD ratio = 1.16–1.21). Clypeus 2/3 below suborbital tangent, apicolateral margins 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 3–4 teeth. Metapostnotum moderately elongate (MMR ratio = 1.25), 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 5.12 mm; head length 1.37 mm; head width 1.32 mm; forewing length 3.17 mm.

Colouration. Flagellum with ventral surface brownish orange-yellow.

Pubescence. Face below antennal sockets with dense tomentum obscuring surface. Upper paraocular area and frons with tomentum partially obscuring surface. Gena with sparse tomentum not obscuring surface.

Surface sculpture. Clypeal punctation moderately dense (i=1–1.5d). Mesoscutum polished, weakly imbricate, punctation between parapsidal lines moderately sparse (i=1–2d). Metanotum obscurely punctate. Preëpisternum and hypoepimeral area reticulate. Mesepisternum weakly imbricate, distinctly and strongly punctate (i≤d). Propodeum with dorsolateral slope reticulate-punctate, lateral surface rugulose, obscurely punctate, posterior surface strongly punctate (i≤d). Metasomal terga apical impressed areas impunctate.

Structure. Head moderately elongate (length/width ratio = 1.04). Eyes strongly convergent below (UOD/ LOD ratio = 1.52). Antennal sockets distant (IAD/OAD> 1.1). Frontal line carinate, ending 1 OD below median ocellus. Pedicel shorter than F1. F2 length 1.5X F1. F2–F10 moderately short (length/width ratio = 1.33–1.50). Metapostnotum moderately elongate (MMR ratio = 1.10), posterior margin rounded onto posterior surface.

Terminalia . S7 with medial lobe elongate, columnar, apex rounded ( Fig. 162F ). S8 with apicomedial margin strongly convex ( Fig. 162F ). Genitalia as in Fig. 162D–E . Gonobase with ventral arms connected. Gonostylus moderately large. Retrorse lobe broad and short, weakly attenuated apically.

Range. Alberta to Saskatchewan, south to southern New Mexico ( Fig. 160 ).

Additional material examined. CANADA: ALBERTA: 2♀ Magreth , 16 km S. McIntyre Ranch, 17– 24.vi.1990 (D. Griffith); [ PMAE] ; MANITOBA: 2♀ 10 km W of Morden , alfalfa field, N49.19587 W098.2503, 410 m, 12.vi.2007 (Goulet & Bouldreault) ; SASKATCHEWAN: 1♀ N of Rocanville, Qu’Appelle R ., N50.5084 W101.7416, 454 m, 2.vi.2007 (Goulet, Boudreault & Fernandez); [ PCYU] ; USA: COLORADO: 1♀ Boulder Co., N39°58´29.9 W105°12´15.6´´, 23.vi.2004 (Kearns & Oliveras) ; 5♀ Larimer Co., N40.6833 W105.3975, 11–12.v.2004 (S.W. Droege) ; MONTANA: 1♀ Pondera Co., Oil Field Rd. , N48.10142 W112.05304, 1135 m, 21.vi.2007 (Gibbs & Sheffield) ; NEW MEXICO: 1♂ Colfax Co., Hwy 64, N36.63692 W104.67754, 1932 m, 6.viii.2007 (Gibbs & Sheffield) ; 1♀ Lincoln Co., Ruidoso , N33.3315 W105.59386, 1969 m, 10.viii.2007 (Gibbs & Sheffield); [ PCYU] .

Floral records. ASTERACEAE : Taraxacum , Verbesina exauriculata , GROSSULARIACEAE : Ribes leptanthum , LINACEAE : Linum lewisii , RANUNCULACEAE : Clematis ligusticifolia , ROSACEAE : Potentilla , SALICACEAE : Salix .

Comments. Common. Preliminary phylogenetic evidence suggests this is a Dialictus sensu strictissimo .

Figures

FIGURE 160. Distribution of Lasioglossum obscurum (dark grey) and L. occidentale (light grey).

FIGURE 161. Lasioglossum occidentale (Crawford). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) forewing; (E) metasomal terga. Scale bars, A–C = 1 mm.

FIGURE 162. Lasioglossum occidentale (Crawford). 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.