Lasioglossum (Dialictus) sitocleptum Gibbs, 2010

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 306-308

Lasioglossum (Dialictus) sitocleptum Gibbs , new species

( Figure 211A–C )

Holotype. ♀ CANADA, Alberta, Writing-On-Stone Prov. Park, Sedge-South , 30.ix.1990 (M. Klassen); [ PMAE]

Diagnosis. Females of L. sitocleptum can be recognised as a parasitic Dialictus by the wide head (length/ width ratio = 0.82–0.85), acute pronotal angle, carinate pronotal ridge, and lack of scopal hairs. They may be further distinguished by the combination of a distinct labral tubercle, relatively small and narrow mandible extending slightly beyond opposing clypeal angle, and relatively narrow gena which does greatly exceed the eye. Lasioglosssum sitocleptum are most similar to the USA species L. simplex (Robertson) which have the mandible shorter, not extending beyond opposing clypeal angle and lack a carinate pronotal ridge. See the diagnosis for L. asteris for other Canadian parasitic Dialictus .

Male unknown.

Description. FEMALE. Length 5.25–5.73 mm; head length 1.22–1.37 mm; head width 1.49–1.63 mm; forewing length 3.42–3.78 mm.

Colouration. Head and mesosoma greenish blue. Clypeus with apical 1/2 blackish brown. Antenna dark brown, flagellum with ventral surface orange-yellow. Tegula dark reddish brown to dark amber. Wing venation and stigma dark yellowish brown. Legs brown, tarsi reddish brown. Metasoma dark brown, terga and sterna with apical margins translucent brownish yellow.

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). Face without appressed hairs. Pronotal collar without dense tomentum. Propodeum with moderately sparse plumose hairs on lateral and posterior surfaces (1.5–2 OD). Mesofemoral and mesotibial combs dense but short relative to non-parasitic species. Metafemoral scopa reduced relative to nest-building species, only a few elongate hairs curving above ventral surface. Penicillus greatly reduced, indistinguishable from other hairs. Metasoma moderately sparse, fine setae. T1 acarinarial fan sparse, incomplete with dorsal opening greater than width of lateral appressed hair patches. T2–T3 basolaterally and T4 entirely with very sparse tomentum. T2 apicolateral and T3–T4 apical margins with very sparse fringes. Sternal hairs erect, posteriorly directed (1.5–2 OD).

Surface sculpture. Face polished, weakly imbricate, punctation fine. Clypeus polished, punctation sparse (i=1–4d). Supraclypeal area with punctation moderately sparse (i=1–3d). Lower paraocular and antennocular areas with punctation moderately sparse (i=1–2d). Upper paraocular area and frons reticulate-punctate. Ocellocular area polished, punctate (i=1–2d). Gena faintly lineolate. Postgena imbricate. Mesoscutum weakly imbricate, more polished posteriorly, punctation fine, sparse between parapsidal lines (i=1–4d), moderately sparse laterad of parapsidal lines (i=0.5–1.5d) and dense on anterolateral portions (i≤d). Mesoscutellum similar to mesoscutum, submedial punctation sparse (i=1–5d). Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate. Mesepisternum dorsal half weakly rugulose, ventral half imbricate. Metepisternum with dorsal third striate, ventral portion imbricate. Metapostnotum completely rugoso-striate, posterior surface imbricate. Propodeum with dorsolateral slope striate, lateral surface imbricate, posterior surface imbricate-tessellate. Metasomal terga polished except apical impressed areas faintly coriarious, punctation on basal halves moderately sparse (i=1–2.5d), apical half sparse (i=2.5–4d).

Structure. Head enormous, very wide (length/width ratio = 0.82–0.85). Eyes convergent below (UOD/ LOD ratio = 1.16–1.20). Labrum enlarged and flattened with distinct basal tubercle, apical process without dorsal keel. Mandibles large, slender, scythe-like, with minute subapical angle. Clypeus 1/3 below suborbital tangent, apicolateral margins strongly convergent. Antennal sockets distant (IAD/OAD> 0.6). Frontal line carinate, ending 2.5 OD below median ocellus. IOD subequal to OOD. Gena broader than eye. Pronotal dorsolateral angle orthogonal. Pronotal ridge uninterrupted. Basitibial plate with lower carina weak. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum truncate (MMR ratio = 1.27–1.35), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina very weak, lateral carina short, not reaching dorsal margin. T5 medial specialized area reduced in size relative to non-parasitic species.

MALE. Unknown.

Range. Southern Alberta east to Saskatchewan ( Fig. 212 ).

Paratypes. CANADA: ALBERTA: 1♀ CFB Suffield, Fish Creek , N50°23.466´W110°36.768´, 7.x.1994 (Finnamore & Pollock) ; 3♀ Writing-On-Stone Prov. Park, Grass-North , 17–26.iv.1990 (D. McCorquodale) ; 1♀ Writing-On-Stone Prov. Park, Birch-North , 26.iv–7.v.1990 (D. McCorquodale) ; 1♀ Writing-On-Stone Prov. Park, Grassland-North , 26.iv–7.v.1990 (D. McCorquodale) ; 1♀ Writing-On-Stone Prov. Park , M. T ., North , 10.ix.1990 (M. Klassen) ; 1♀ Writing-On-Stone Prov. Park, Willow-North , 10.ix.1990 (D. McCorquodale); [ PMAE] ; SASKATCHEWAN: 2♀ Saskatoon , 28.iv.1949 (A. R. Brooks) ; 1♀ Saskatoon , 5.v.1949 (A. R. Brooks); [ CNC] .

Etymology. The specific epithet is derived from the Greek words for food “sitos” and thief “klepto”.

Comments. Rare. This is a parasitic species. Host unknown. Lasioglossum sitocleptum is the most westernly distributed of the North American parasitic Dialictus .

Figures

FIGURE 211. Lasioglossum sitocleptum Gibbs. Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 212. Distribution of Lasioglossum sitocleptum (black), L. subversans (light grey), and L. subviridatum (dark grey).