Lasioglossum (Dialictus) lilliputense 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 : 178-180

Lasioglossum (Dialictus) lilliputense Gibbs , new species

( Figure 136A–D )

Holotype. 1♀ USA, Montana, Gallatin Co., N44.80377 W111.17462, 2030 m, 23.vi.2007 (Gibbs & Sheffield); [ PCYU].

Diagnosis. Female L. lilliputense can be recognised by diagnostic combination of small size, head moderately elongate (length/width ratio = 1.06), mesoscutal punctures bimodal and well spaced between parapsidal lines (i=1–1.5d), mesepisternal distinctly and finely punctate (i=d), T1 fan without dorsal opening, metasomal terga brown, T2–T3 with apical impressed areas punctate, very sparse tomentum mostly limited to T4, and T3–T4 without apical fringes.

Male unknown.

Description. FEMALE. Length 4.11–4.54 mm; head length 1.26–1.37 mm; head width 1.19–1.30 mm; forewing length 3.15–3.33 mm.

Colouration. Head and mesosoma golden green, sometimes with bluish reflections. Clypeus with apical half blackish brown, basal half, and supraclypeal area brassy. Antenna dark brown. Tegula dark reddish brown. Wing membrane subhyaline, venation and pterostigma reddish brown. Wings slightly dusky. Metasoma lustrous brown, terga and sterna with apical margins reddish to translucent yellowish brown.

Pubescence. Dull white. Very sparse. Head and mesosoma with sparse woolly hairs (1 OD), longest on genal beard, metanotum and mesopleuron (1.5–2 OD). Lower paraocular area without tomentum. Propodeum with sparse plumose hairs on lateral and posterior surfaces (1–2 OD). Metasomal terga with fine setae. T1 acarinarial fan complete, without dorsal opening. T3 basolaterally and T4 with very sparse tomentum. T3–T4 without apical fringes.

Surface sculpture. Face imbricate, punctation strong. Clypeus polished, basal margin imbricate, punctation moderately sparse (i=1–2.5d). Supraclypeal area with punctation sparse (i=1–2d). Lower paraocular area punctation dense (i≤d). Antennocular area punctation moderately dense (i=1d). Upper paraocular area and frons reticulate-punctate. Ocellocular area punctate (i≤d). Gena and postgena lineolate. Mesoscutum imbricate, punctation size bimodal, moderately sparse between parapsidal lines (i=1–1.5d), dense laterad of parapsidal lines (i≤d), contiguous on anterolateral portion. Mesoscutellum polished, punctation similar to mesoscutum, submedial punctation sparse (i=1–2.5d). Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Mesepisternum weakly imbricate between distinct punctures (i≤d). Metepisternum with dorsal half ruguloso-striate, ventral half imbricate. Metapostnotum incompletely striate, posterior margin imbricate. Propodeum with dorsolateral slope ruguloso-imbricate, lateral and posterior surfaces tessellate. Metasomal terga polished except apical impressed areas distinctly coriarious, punctation fine, on basal halves close (i=1– 1.5d), sparse on apical half (i=2–4d).

Structure. Head moderately elongate (length/width ratio = 1.06). Eyes convergent below (UOD/LOD ratio = 1.18–1.19). Clypeus ¾ 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 2–3 teeth. Metapostnotum moderately elongate (MMR ratio = 1.04–1.16), posterior margin rounded onto posterior surface. Propodeum with oblique carina indistinct, lateral carina reaching 2/3 distance to dorsal margin.

MALE: Unknown.

Range. Southern British Columbia to Idaho and Montana ( Fig. 135 ).

Paratypes. CANADA: BRITISH COLUMBIA: 3♀ East Kootenay Reg. Dist., Grasmere , N49.0727 W115.1216, 825 m, 18.viii.2009 (L. R. Best); [ PCYU] ; USA: IDAHO: 1♀ Blaine Co., Ketchum , Sawtooth Bot. Gard., 1726 m, 24.vi.2007 (Gibbs & Sheffield) ; 1♀ Fremont Co., Hwy 20, N44.39329 W111.36278, 2032 m, 23.vi.2007 (Gibbs & Sheffield); [ PCYU] .

Etymology. The specific epithet is a reference to the small size of this bee, even relative to many other Dialictus .

Comments. Uncommon. Mexican material from Puebla and Veracruz similar to L. lilliputense have been examined that do not differ in DNA barcodes. Two additional species which are similar have been examined from Utah and Missouri respectively. Lasioglossum obnubilum (Sandhouse) , described from Colorado, may be the male of L. lilliputense or one of the related species.

Figures

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

FIGURE 136. Lasioglossum lilliputense new species. Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mesepisternum. Scale bars, A–C = 1 mm.