Lasioglossum (Dialictus) pictum (Crawford)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 249-253

Lasioglossum (Dialictus) pictum (Crawford)

( Figures 178A–D , 179A–F )

Halictus pictus Crawford, 1902: 236 . ♀.

Syntypes. 2♀ USA, Nebraska, Crawford , Sioux Co., 29.vii.1901 on Mentzelia, (M.A. Carriker) ; [ UNSM]. Examined .

Halictus graenicheri Ellis, 1914 b: 221 . ♀.

Holotype. 1♀ USA, Wisconsin, Genoa , Vernon Co., Wisconsin, 13–19.vii.1911; [ NMNH: 27761]. Examined. Dialictus muskegonensis Mitchell, 1960: 439 . ♂.

Holotype. ♂ USA, Michigan, Muskegon Co., 2.viii.1944, ( R. R. Dreisbach); [ NCSU]. Examined.

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) graenicheri , p. 1113, L. (C.) pictum , p. 1116 (catalogue); Krombein, 1958: Lasioglossum (Chloralictus) graenicheri , p. 230, (catalogue); Mitchell, 1960: Dialictus pictus ♀, p. 412 (redescription, synonymy); Mitchell, 1962: Dialictus pictus , p. 547 (synonymy); Krombein, 1967: Lasioglossum (Dialictus) pictum , p. 465 (catalogue); Hurd, 1979: Dialictus pictus , p. 1970 (catalogue); Moure & Hurd, 1987: Dialictus pictus , p. 122 (catalogue).

Diagnosis. Females of L. pictum can be recognised by the orange-yellow metasoma, blackish brown apical half of the clypeus, moderately sparse tomentum on the lower paraocular area, reticulate-punctate mesepisternum, primarily brown legs, and obscure punctures on the apical impressed areas of the metasomal terga. They are most similar to L. hudsoniellum which have the apical half of the clypeus brownish red, dense tomentum on the lower paraocular area and deep punctures on the apical impressed punctures on the mesepisternum. Females of both L. (E.) testaceum and L. vierecki have brownish yellow metasoma but differ as follows. Female L. testaceum have strong propodeal carinae and rugulose mesepisternum. Female L. vierecki have the mesoscutum obscured by dense yellowish tomentum and extensively brownish yellow legs.

Males of L. pictum can be recognised by the moderately elongate head (length/width ratio = 0.98–1.02), lower face with moderately dense tomentum, short flagellomeres with the ventral surface orange-yellow; moderately sparse mesoscutal punctation (i=1–2d), fine parapsidal lines, distinct mesepisternal punctures, metasomal reddish brown with apical margins orange-yellow. They are most similar to L. foveolatum which has a very deep and wide parapsidal lines and brown metasomal terga.

Redescription. FEMALE. Length 4.76–5.49 mm; head length 1.32–1.51 mm; head width 1.44–1.54 mm; forewing length 3.66–4.02 mm.

Colouration. Head and mesosoma pale green to bluish green. Labrum reddish brown to yellow. Mandibles brown to yellow. Clypeus with apical half blackish brown and basal half, and supraclypeal area bronze. Antenna dark brown, flagellum with ventral surface orange-brownish yellow. Tegula pale brownish yellow. Wing membrane subhyaline, venation and pterostigma pale amber. Legs brown, tibial bases and sometimes apices, meso- and metabasitarsus, and medio- and distitarsi red to brownish yellow, basitarsus suffused with brown. Propodeum with dorsal surface blue. Metasoma terga pale orange-yellow; terga and sterna with apical 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 subappressed tomentum, not obscuring surface. Metepisternum obscured by tomentum. 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 (obscure on pale background). T2 basolateral and T3–T5 with moderately dense tomentum largely obscuring surface. T2 apicolateral and T3–T4 apical margins with weak fringes.

Surface sculpture. Face imbricate, punctation moderately strong. Clypeus with apical half polished, punctation moderately sparse (i=1–2.5d). 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, frons and ocellocular area punctate-reticulate. Gena and postgena lineolate. Mesoscutum weakly imbricate, polished submedially, punctation dense between parapsidal lines (i≤d), contiguous laterad of parapsidal lines and punctate-reticulate on anterolateral portions. Mesoscutellum polished, submedial punctation sparse (i=1–3d). Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate-punctate. Mesepisternum rugulose-punctate (i≤d), more polished below. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum with complete, rugoso-striate, posterior margin rounded and raised. Propodeum with dorsolateral slope and lateral surface weakly rugulose, posterior surface imbricate. Metasomal terga polished except apical impressed areas weakly coriarious, punctation fine throughout, close on basal halves (i=1–2d), more widely spaced on marginal zone (i=1–3d).

Structure. Head wide (length/width ratio = 0.92–0.98). Eyes convergent below (UOD/LOD ratio = 1.19– 1.24). Clypeus 1/2 below suborbital tangent, apicolateral margins strongly convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. Gena narrower than eye. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum truncate (MMR ratio = 1.30–1.45), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina obscure, lateral carina weak, not reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length. 5.37– 5.55mm; head length 1.30–1.39 mm; head width 1.32–1.42 mm; forewing length 3.54–3.72 mm.

Colouration. Labrum and mandible pale yellow. Legs brown, Pro- and mesotibia, and metatibial base and apex, and tarsi brownish yellow; pro- and mesotibia dorsal surface brown. Metasoma reddish brown, darker posteriorly; terga apical margins orange to brownish yellow; S1–S4 orange.

Pubescence. Face below eye emargination with subappressed tomentum obscuring paraocular area and partially obscuring clypeus and supraclypeal area. Metasomal terga without appressed tomentum. S2–S3 apical portions with erect, plumose hairs (1–1.5 OD). S4–S5 disc with erect, plumose hairs (1–1.5 OD).

Surface sculpture. Surface more polished. Mesoscutum polished, punctation moderately sparse between parapsidal lines (i=1–2d), closer laterad of parapsidal lines (i≤d), contiguous on anterolateral portions. Mesepisternum closely punctate (i≤d). Metapostnotum striate. Propodeum with dorsolateral slope and lateral and posterior surfaces rugulose. Metasomal terga with punctation deep and distinct across disc (i=1–1.5d), marginal zones with a few punctures basomedially.

Structure. Head moderately elongate (length/width ratio = 0.98–1.02). Eyes strongly convergent below (UOD/LOD ratio = 1.42–1.43). Clypeus with apicolateral margins subparallel. Antennal sockets distant (IAD/ OAD <1.0). Frontal line carinate, ending 2 OD below median ocellus. Pedicel shorter than F1. F2 length 1.6– 1.8X F1. F2–F10 moderately short (length/width ratio = 1.25–1.45). Metapostnotum moderately elongate (MMR ratio = 1.20–1.33), posterior margin weakly angled onto posterior surface.

Terminalia . S7 with median lobe columnar, apex rounded ( Fig. 179F ). S8 with apicomedial margin strongly convex ( Fig.179F ). Genitalia as in Fig. 179D–E . Gonobase with ventral arms narrowly separated. Gonostylus small. Retrorse lobe wide and short, rounded apically.

Range. Ontario west to Alberta and Nebraska ( Fig. 177 ).

Additional material examined. CANADA: ALBERTA: 1♂ CFB Suffield , Amiens, N50°37.678´W110°18.371´, 16.viii . MANITOBA: 1♀ YellowQuill Mxd. Grass Prairie Preserve, near Treesbank , N49°41´28´´ W099°34´29´´, 15.vi.2005 (A.M. Patenaude) ; 1♀ YellowQuill Mxd. Grass Prairie Preserve, near Treesbank , N49°41´28´´ W099°34´29´´, 20.vi.2005 (A.M. Patenaude) ; 1♀ YellowQuill Mxd. Grass Prairie Preserve, near Treesbank , N49°41´28´´ W099°34´29´´, 16.viii.2005 (A.M. Patenaude) ; ONTARIO: 1♀ Leamington , 6.vi.1961 (G. Knerer) ; 7♀ Long Point , 20–23.vi.1996 (P.J. Carson) ; 1♂ Rondeau Pk. , 19.ix.1961 (G. Knerer); [ PCYU] ; SAKATCHEWAN: 1♂ Sask. Landing , 23.vii.1956 (O. Peck); [ CNC] ; USA: INDIANA: 1♀ Newton Co., Conrad , 30.vii.2003 ( R. P Jean); [ PCYU] ; MICHIGAN: 1♀ Cass Co., Cassapolis , 20.vii.2009 (Tuell et al.); [ ARC] ; MINNESOTA: 1♀ Clay Co., 4 mi E, 1 mi S Glyndon , 24.v.2005 ( R. L. Andres) ; 1♀ Clay Co., 4 mi E, 1 mi S Glyndon , 10.vi.2005 ( R. L. Andres) ; 4♀ Sher Co., Zimmerman, Sherburne NWR , 10.vii.2001 (S. Droege); [ PCYU] ; NEBRASKA: 1♀ paratype West Pt. , 10.vi.1901 (J.C. Crawford); [ NMNH] .

Floral records. ASTERACEAE : Erigeron philadelphicus , Solidago , BRASSICACEAE : Lepidium , FABACEAE : Melilotus , HYDROPHYLLACEAE : Phacelia congesta , LAMIACEAE : “ Salviastrum texanum , ” LOASACEAE : Mentzelia , ROSACEAE : Rosa , SALICACEAE : Salix .

Biology. Knerer & Atwood, 1962: (nest site, geography, floral records).

Comments. Relatively common. DNA barcodes of L. pictum cannot be clearly differentiated from those of L. foveolatum . These species do not seem similar morphologically.

Figures

FIGURE 177. Distribution of Lasioglossum perpunctatum (light grey) and L. pictum (dark grey).

FIGURE 178. Lasioglossum pictum (Crawford). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mesoscutum. Scale bars, A–C = 1 mm.

FIGURE 179. Lasioglossum pictum (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.