Lasioglossum (Dialictus) leucocomum (Lovell) 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 : 175-178

Lasioglossum (Dialictus) leucocomum (Lovell) , new combination

( Figure 134A–C )

Halictus pilosus var. leucocomus Lovell, 1908: 37 . ♀. Lectotype. ♀ USA, Maine, Waldoro , 28.v.1905 (J.H. Lovell); [NMNH: 71569] by T. B. Mitchell. Examined.

Diagnosis. Most similar to L. pilosum and L. succinipenne . See diagnosis for L. pilosum .

Redescription. FEMALE. Length 5.06–5.80 mm; head length 1.51–1.61 mm; head width 1.44–1.56 mm; forewing length 3.78–3.90 mm.

Colouration. Head and mesosoma pale green to golden green. Clypeus with apical half blackish brown. Supraclypeal area bronze. Antenna dark brown, flagellum with ventral surface brownish yellow. Tegula amber to translucent brownish yellow. Wing membrane subhyaline, venation and pterostigma pale amber. Legs brown, protibial base, medio- and distitarsi reddish brown. Metasomal terga golden green, sterna brown, apical margins pale, translucent yellow.

Pubescence. Dull white. Dense. Head and mesosoma with moderately 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 portions with dense tomentum. T2 basal and lateral portions with dense tomentum obscuring surfaces. T3–T5 with dense tomentum obscuring surface. T2–T4 apical margins with moderately dense fringes.

Surface sculpture. Face imbricate, punctation fine. Clypeus polished, punctation (i=1–3d). Supraclypeal area with punctation moderately dense (i=1–2.5d). Lower paraocular and antennocular areas with punctation dense (i≤d). Upper paraocular area and frons punctate-reticulate. Ocellocular area minutely punctate (i≤d). Gena and postgena lineolate. Mesoscutum weakly imbricate, punctation fine, dense on medial portion of disc (i<d), punctate-reticulate mesad and laterad of parapsidal lines and on anterolateral portions. Mesoscutellum polished, submedial punctation moderately dense (i=1–2d). Axilla punctate. Metanotum ruguloso-imbricate. Preëpisternum rugulose. Hypoepimeral area rugulose. Mesepisternum weakly rugulose. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum weakly, incompletely rugoso-striate, posterior margin imbricate. Propodeum with dorsolateral slope imbricate, lateral surface ruguloso-imbricate, poste rior surface imbricate-tessellate. Metasomal terga weakly coriarious, punctation moderately dense throughout (i=1–1.5d).

Structure. Head elongate (length/width ratio = 1.03–1.06). Eyes convergent below (UOD/LOD ratio = 1.15–1.23). Clypeus ½ below suborbital tangent, apicolateral margins 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 4 teeth. Metapostnotum truncate (MMR ratio = 1.36–1.45), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina fine, lateral carina short, not reaching dorsal margin.

MALE. Unknown.

Range. Nova Scotia, Maine west to Ontario, Michigan ( Fig. 135 ).

Additional material examined. CANADA: NEW BRUNSWICK: 2♀ Kent Co., St. Ignace , N46.707 W071.054, 31.vii.2005 (M. Gravel) ; NOVA SCOTIA: 1♀ Kings Co., Up Canard , N45.135 W064.489, 17.v.2003 (C. Sheffield) ; ONTARIO: 1♀ QUBS , 6–14.viii.2005 (L. Packer); [ PCYU] .

Floral records. Additional records attributed to L. pilosum likely apply to this species. ASTERACEAE : Solidago , ROSACEAE : Crataegus coccinea .

Comments. Common. Lasioglossum leucocomum has long been considered a synonym of L. pilosum ( Michener 1951) . Lovell (1908) described it as a variant of L. pilosum . DNA barcodes corroborate the morphological characters recognised by Lovell (1908). Sequence divergence between L. leucocomum and L. pilosum is approximately 8%. Indeed, the molecular data suggests a stronger similarity to L. succinipenne and L. pruinosum .

Figures

FIGURE 134. Lasioglossum leucocomum (Sandhouse). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 135. Distribution of Lasioglossum leucocomum (light grey) and L. lilliputense (dark grey).