Lasioglossum (Dialictus) dubitatum (Mitchell)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 114-116

Lasioglossum (Dialictus) dubitatum (Mitchell)

(Figure 100A–E)

Dialictus dubitalus Mitchell, 1960: 436 . ♂. lapsus calami (spelled D. dubitatus in key, p. 376 and index, p. 533) Holotype. ♂ USA, New York, McLean Bogs, Cortland Co., June 20.vi.1936 [CUIC: 4890]. Examined.

Taxonomy. Krombein, 1967: Lasioglossum (Dialictus) dubitatum , p. 463 (catalogue); Hurd, 1979: Dialictus dubitatus , p. 1966 (catalogue); Moure & Hurd, 1987: Dialictus dubitatum , p. 100 (catalogue).

Diagnosis. Male L. dubitatum are recognisable by their short and wide hind basitarsus which is approximately three times as long as broad (Fig. 100D). Other species have the hind basitarsus four times as long as broad. Otherwise this species is most similar to L. versatum which is virtually identical in all respects except this species has a long and narrow hind basitarsus approximately four times as long as broad. See diagnosis for L. versatum .

FEMALE. Unknown.

MALE. Length. 5.00 mm; head length 1.49 mm; head width 1.48 mm; forewing length 3.84 mm.

Colouration. Head and mesosoma bluish green. Mandible orange. Clypeus with apical half reddish brown. Antenna dark brown, flagellum with ventral surface yellowish orange. Tegula dark reddish brown. Wing membrane subhyaline, venation and pterostigma brownish yellow. Legs brown, tibial apices and bases and tarsi reddish brown. Metasoma dark brown, terga and sterna with apical margins reddish brown to translucent brownish yellow.

Figure 100. Lasioglossum dubitatum (Mitchell) . Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) metabasitarsus; (E) terminalia. Scale bars, A–C = 1 mm, E = 0.5 mm.

Pubescence. Dull white. Moderately sparse. Head and mesosoma with moderately sparse woolly hairs (1– 1.5 OD), longest on genal beard, metanotum and mesopleuron (1.5–2 OD). Face below eye emargination with sparse tomentum not obscuring surface except lower paraocular and antennocular areas with moderately dense tomentum, partially obscuring surface. Gena with sparse tomentum. Propodeum with moderately sparse plumose hairs on lateral and posterior surfaces (1.5–2 OD). Metasomal terga with sparse, fine setae. T2–T3 basolaterally with very small patches of tomentum. S3 apicolateral and S4–S5 lateral portions with moderately dense plumose hairs.

Surface sculpture. Face imbricate, punctation fine, shallow. Clypeus with apical half polished, punctation moderately dense (i=1–1.5d). 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 and frons punctate-reticulate. Ocellocular area punctate (i=d). Gena weakly lineolate. Postgena imbricate. Mesoscutum tessellate-imbricate, punctation fine, shallow, sparse between parapsidal lines (i=1– 3d), dense laterad of parapsidal line (i=d), rugulose-punctate on anterolateral portion. Mesoscutellum apparently similar to mesoscutum [mostly obscured by pin]. Axilla minutely punctate. Metanotum rugulose. Preëpisternum rugose. Hypoepimeral area rugulose. Mesepisternum rugose. Metepisternum with dorsal half weakly rugose, ventral half imbricate. Metapostnotum completely rugoso-striate. Propodeum with dorsolateral slope and lateral and posterior surfaces rugose. Metasomal terga polished, punctation on basal halves moderately dense (i=1.5d), sparse on apical half, including apical impressed areas (i=2–3d).

Structure. Head relatively elongate (length/width ratio = 1.01). Eyes strongly convergent below (UOD / LOD ratio = 1.54). Clypeus 2/3 below suborbital line, anterolateral margins weakly convergent. Antennal sockets distant (IAD/OAD> 1.4). Frontal line carinate, ending 2 OD below median ocellus. Pedicel shorter than F1. F2 length 1.7X F1. F2–F10 moderately elongate (length/width ratio = 1.43–1.64). Gena narrower than eye. Metabasitarsus short and broad, 3 times as long as broad. Metapostnotum truncate, posterior margin angled. Propodeum with oblique carina virtually absent, lateral carina moderately strong, reaching 2/3 of the distance to dorsal margin.

Terminalia . S7 median lobe clavate, apex rounded (Fig. 100E). S8 posterior margin weakly convex (Fig. 100E). Genitalia as in Fig. 100E. Gonobase with ventral arms widely separated. Gonostylus small, dorsal setae elongate. Retrorse lobe narrow, attenuated apically.

Range. New York, possibly Ontario and Quebec ( Fig. 99 ).

Comments. Rare. Lasioglossum dubitatum is nearly identical to the commonly collected L. versatum except for the shape of the metabasitarsus. Additional material is needed to determine the relationship of these two species for which DNA barcoding may assist. The Canadian records cannot be confirmed but the species is included due to the proximity of the type locality to Ontario.

Figures

FIGURE 99. Distribution of Lasioglossum dreisbachi (light grey), and L. dubitatum (dark grey).