Lasioglossum (Dialictus) pruinosum (Robertson)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 269-273

Lasioglossum (Dialictus) pruinosum (Robertson)

( Figures 189A–C , 190A–F )

Halictus pruinosus Robertson, 1892: 269 . ♀ ♂. Lectotype. ♀ USA, Illinois, Carlinville (Robertson); [INHS: 179,615] by W.E. LaBerge. Examined.

Taxonomy. Robertson, 1902: Chloralictus pruinosus , p. 248 (key); Cockerell, 1909: Halictus pruinosus , p. 9 (tax. comp.); Michener, 1951: Lasioglossum (Chloralictus) pruinosum , p. 1116 (catalogue); Mitchell, 1960: Dialictus pruinosus ♀, p. 415 (redescription); Krombein, 1967: Lasioglossum (Dialictus) pruinosum , p. 465 (catalogue); Dialictus pruinosus , p. 1970 (catalogue); Moure & Hurd, 1987: Dialictus pruinosus , p. 125 (catalogue).

Diagnosis. Females of L. pruinosum can be recognised by the diagnostic combination of an elongate head (length/width ratio = 1.05–1.09), mesoscutal punctation dense (i<d) except on medial portion (i=1–1.5d), rugulose mesepisternum, hyaline wings, nearly white pterostigma, and abundant tomentum across the metasomal terga. They are most similar to L. succinipenne which have the mesoscutal punctures dense throughout.

Males of L. pruinosum can be recognised by the diagnostic combination of an elongate head (length/width ratio = 1.18–1.21) covered in dense white tomentum, yellow apical margin of the clypeus, short flagellomeres (length/width ratio = 1.15–1.30) that are bright yellow ventrally, moderately sparse mesoscutal punctation medially (i=1–2d), rugoso-reticulate mesepisternum, and bluish green metasoma terga with strong punctation. They are most similar to L. albipenne which lack a yellow band on the clypeus and have brown metasomal terga.

Redescription. FEMALE. Length 5.62–6.85 mm; head length 1.56–1.68 mm; head width 1.49–1.56 mm; forewing length 3.97–4.45 mm

Colouration. Head and mesosoma pale greenish blue. Clypeus with apical half blackish brown, basal half and supraclypeal area golden. Antenna dark brown, flagellum with ventral surface reddish brown. Tegula amber. Wing membrane hyaline, venation and pterostigma pale whitish yellow. Legs blackish brown, medio- and distitarsi reddish brown. Metasomal terga greenish blue, sterna brown, apical margins translucent yellow.

Pubescence. Dull white. Dense. Head and mesosoma with dense woolly hairs (1–1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Paraocular area and gena with subappressed tomentum sometimes partially obscuring surface. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with dense, fine setae. T1 acarinarial fan complete and dense. T1 apicolateral portion with dense tomentum. T2 basal and lateral portions with dense tomentum obscuring surfaces. T3–T5 with dense tomentum obscuring surface. T2 apicolateral and T3–T4 apical margins with moderately dense fringes.

Surface sculpture. Face imbricate, punctation moderately strong. Clypeus polished, basal margin weakly imbricate, punctation moderately sparse (i=1–2.5d). Supraclypeal area polished medially, 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 densely, finely punctate (i<d). Gena and postgena lineolate. Mesoscutum imbricate, punctation moderately dense on medial portion of disc (i=1–1.5d), reticulate-punctate laterad and mesad parapsidal lines and on anterolateral por tions. Mesoscutellum similar to mesoscutum, submedial punctation moderately sparse (i=1–2d). Axilla punctate. Metanotum imbricate. Preëpisternum and hypoepimeral area rugulose. Mesepisternum dorsal half rugulose, ventral half weakly ruguloso-imbricate. Metepisternum with dorsal third weakly rugoso-striate, ventral portion imbricate. Metapostnotum incompletely rugoso-striate, posterior margin imbricate. Propodeum with dorsolateral slope, lateral and posterior surfaces imbricate. Metasomal terga weakly coriarious, punctation fine and moderately dense throughout (i=1–2d).

Structure. Head elongate (length/width ratio = 1.05–1.09). Eyes convergent below (UOD/LOD ratio = 1.28–1.30). Clypeus 1/2–2/3 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 = 1.14–1.19), posterior margin rounded onto posterior surface. Propodeum with oblique carina weak, lateral carina weak, not reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.94– 5.61 mm; head length 1.44–1.80 mm; head width 1.22–1.49 mm; forewing length 3.36–3.78 mm.

Colouration. Labrum, mandibles, clypeus distal margin, flagellum ventral surface, Tibial bases and apices, and tarsi pale yellow. Flagellum with ventral surface yellow-brownish to yellow.

Pubescence. Face below upper eye tangent with dense tomentum obscuring surface. T1 acarinarial area with sparse fan of appressed hairs. T1 apicolateral portion, T2–T3 lateral portions, and T4–T5 basal portions with tomentum. S2–S3 and S4–S5 lateral portions with dense plumose hairs (1–1.5 OD).

Surface sculpture. More polished, punctation moderately dense between parapsidal lines (i=1–2d), closer laterad of parapsidal lines (i≤d) and reticulate on anterolateral portion. Mesepisternum rugulose-reticulate. Propodeum with dorsolateral slope and lateral and posterior surfaces rugulose. Metasomal terga punctation deep and distinct.

Structure. Head very elongate (length/width ratio = 1.18–1.21). Eyes strongly convergent below (UOD/ LOD ratio = 1.39–1.50). Clypeus 8/10 below suborbital tangent, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD> 1.1). Frontal line carinate, ending 1.5 OD below median ocellus. Pedicel subequal to F1. F2 length 1.3–1.6X F1. F2–F10 short (length/width ratio = 1.15–1.30). Metapostnotum moderately elongate (MMR ratio = 1.08–1.30), posterior margin rounded.

Terminalia . S7 with median lobe wide, columnar, apex rounded ( Fig. 190F ). S8 with apicomedial margin weakly convex ( Fig. 190F ). Genitalia as in Fig. 190D–E . Gonobase with ventral rim narrowly separated. Gonostylus small, slender, dorsal setae elongate. Retrorse lobe elongate, attenuated apically.

Range. British Columbia and south to Arizona east to Northeastern USA ( Fig. 191 ).

Additional material examined. CANADA: ALBERTA: 2♀ CFB Suffield, Fish Creek , N50°23.466´W110°36.768´, 28.vii.1994 (Finnamore & Pollock) ; 1♀ 4♂♂ CFB Suffield, Fish Creek , N50°23.466´W110°36.768´, 7.ix.1994 (Finnamore & Pollock); [ PCYU] ; 1♂ Medicine Hat (J. R. Malloch); [ ANSP]; BRIT- ISH COLUMBIA: 10♀ East Bench , 17.v–12.vii.2007 (Scudder); [ PCYU] ; 1♂ Penticton, West Bench , 22.viii.1987 ( R. A. Cannings) ; 1♂ Penticton, West Bench , 24.viii.1987 ( R. A. Cannings); [ RBCM]; MANI- TOBA: 1♀ YellowQuill Mxd. Grass Prairie Preserve, near Treesbank , N49°50´51´´ W099°33´15´´, 5.ix.2005 (A.M. Patenaude) ; 2♀ YellowQuill Mxd. Grass Prairie Preserve, near Treesbank , N49°50´51´´ W099°33´16´´, 20.ix.2005 (A.M. Patenaude) ; 1♀ YellowQuill Mxd. Grass Prairie Preserve, near Treesbank , N49°50´51´´ W099°33´15´´, 16.viii.2005 (A.M. Patenaude) ; 1♀ YellowQuill Mxd. Grass Prairie Preserve, near Treesbank , N49°41´26´´ W099°34´29´´, 30.viii.2005 (A.M. Patenaude) ; SASKATCHEWAN: 1♀ Grassland N.P., N49.0711 W106.52935, 830 m, 4.vi.2007 (Goulet, Boudreault & Fernandez); [ PCYU] ; USA: ARI- ZONA: 7♀ Apache Co., 23 km W of Zuni, Kelsey Rd + Hwy 61, 14.vi.1999 (L. Packer) ; 1♀ Apache Co., 33 km W of Zuni NM, 14.vi.1999 (L. Packer) ; COLORADO: 2♀ Larimer Co., N40.6833 W105.3975, 11– 12.v.2004 (S.W. Droege); [ PCYU] ; IDAHO: 1♀ Oneida Co., Rock Creek , 21.vii.1971 (G.F. Knowlton); [ CUIC] ; INDIANA: 3♀ Jackson Co., N38.8799 W086.056, 26.vii.2003 (S.W. Droege) ; IOWA: 1♀ Dickinson Co., Iowa Northwestern RR, 4.2 km NW Spirit Lake, N43°26´20´´ W095°10´54´´, 439 m, 21.v.2003 (C. Hemsley); [ PCYU] ; MICHIGAN: 2♀ Cass Co., Cassopolis , N41.9148 W85.9785, 22.vii.2009 (Tuell et al.); [ ARC] ; MINNESOTA: 1♀ Clay Co., 3mi E & 2mi S of Felton , N47°03´38.8´´ W96°26´07.4´´, 21.vii.2006, ( R. L. Andres) ; NEBRASKA: 2♀ Douglas Co., N41.2796 W095.9073, 10.v.2007 (S.W. Droege) ; UTAH: 1♀ Kane Co., Red Wash , 2.6 mi SSE Carly Knoll, 12S N4126481 E382273, 23.v.2001 ( R. Andrus) ; 1♀ Washington Co., 0.73 mi SE Firepit Kn. , 12S N4135295 E314678, 5.vii.2006 (F. Nicklen & B. Hays); [ PCYU]; WIS- CONSIN: 1♀ Dane Co., Hauser Rd. ( R. A. Henderson); [ IRCW] .

Floral records. ANACARDIACEAE : Rhus glabra , APIACEAE : Zizia aurea , Perideridia americana , Polytaenia nuttallii , ASTERACEAE : Antennaria plantaginifolia , Bidens aristosa , Boltonia asteroides , Chrysothamnus viscidiflorus , Cirsium discolor , Coreopsis palmata , Echinacea pallida , Erigeron strigosus , Heliopsis helianthoides , Packera aurea , Ratibida pinnata , Rudbeckia hirta , Senecio serra , Symphyotrichum pilosum , Vernonia fasciculata , BERBERIDACEAE : Mahonia repens , BRASSICACEAE : Cardamine bulbosa , Descurainia pinnata , CAPPARACEAE : Cleome serrulata , COMMELINACEAE : Tradescantia virginiana , CORNACEAE : Cornus amomum , FABACEAE : Dalea purpurea , Medicago , Melilotus officinalis , IRIDACEAE : Gladiolus , Sisyrinchium angustifolium , LAMIACEAE : Monarda , Pycnanthemum flexuosum , Scutellaria parvula , LILIACEAE : Camassia scilloides , Lilium perenne , ONAGRACEAE : Ludwigia alternifolia , OXALIDACEAE : Oxalis corniculata , PASSIFLORACEAE : Passiflora lutea , RANUNCULACEAE : Ranunculus fascicularis , RHAMNACEAE : Rhamnus lanceolata , ROSACEAE : Geum canadense , Prunus americana , SALICACEAE : Salix cordata , S. humilis , S. nigra , SAXIFRAGACEAE : Heuchera americana hispida , SCROPHULARIACEAE : Penstemon laevigatus , Veronica peregrina , VERBENACEAE : Verbena hastata .

Biology. Melander & Brues, 1903: (parasites, predators, associate organisms); Sakagami & Michener, 1962, pp. 36: (nest orientation).

Comments. Common in western parts of its range.

Figures

FIGURE 189. Lasioglossum pruinosum (Robertson). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 190. Lasioglossum pruinosum (Robertson). 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.

FIGURE 191. Distribution of Lasioglossum pruinosum (light grey) and L. punctatoventre (dark grey).