Lasioglossum (Dialictus) ascheri Gibbs

Gibbs, Jason, 2011, Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini), Zootaxa 3073, pp. 1-216 : 57-59

Lasioglossum (Dialictus) ascheri Gibbs , new species

( Figure 67–68 )

Holotype. Ƥ USA, New York, Westchester Co., Pleasantville, Fellows Garden, 27.vi.2005, on Oenothera (E. Fetridge) ; [ AMNH].

Diagnosis. Female L. ascheri can be recognised by diagnostic combination of labrum wide, flat, dorsal keel absent; mandible without preapical tooth; gena much wider than eye; mesepisternum punctate; metapostnotum rugoso-carinulate; tibial scopa reduced; and inner metatibial spur with long branches. Lasioglossum curculum is most similar but has a distinct preapical tooth on the mandible and has short branches on inner metatibial spur, not much wider than rachis. Lasioglossum rozeni are similar but have widely divergent hypostomal carinae, mandible narrower, and mesepisternum impunctate. Lasioglossum cephalotes and L. lionotum have the metapostnotum smooth.

Male unknown.

Description. FEMALE. Length mm 4.88–5.13; head length 1.40–1.45 mm; head width 1.78–1.80 mm; forewing length 3.81–4.13 mm.

Colouration. Head and mesosoma purplish with blue reflections. Clypeus apical portion blackish brown. Antenna dark brown, flagellum with ventral surface orange-yellow. Tegula reddish brown. Wing membrane subhyaline, venation and pterostigma reddish brown. Legs brown, except tarsi brownish yellow. Metasoma reddish brown, terga and sterna margins translucent reddish to yellowish brown.

Pubescence. Dull white. Sparse. Head and mesosoma with moderately dense woolly hairs (1–1.5 OD), longest on genal beard, metanotum, and mesopleuron (1.5–2 OD). Face without appressed hairs. Clypeus distal margin with long bristles (2–3 OD). Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (1.5–2 OD). Mesofemoral and mesotibial combs present but sparse relative to non-parasites. Femoral scopa greatly reduced, only a few long, curved hairs remain. Penicillus reduced relative to non-parasites. Metasomal terga with sparse, fine hairs and no tomentum. T1 acarinarial fan with wide dorsal opening. T2–T3 apicolateral and T4 apical margins with very sparse fringes. Metasomal sterna with sparse posteriorly curved hairs (2–3 OD).

Surface sculpture. Face polished, punctation fine. Clypeus with punctation sparse (i=1–4d). Supraclypeal area punctation fine, sparse (i=1–2.5d). Lower paraocular area punctation dense (i=1–2d). Antennocular area punctation moderately dense (i=1–1.5d). Upper paraocular area and frons reticulate-punctate. Ocellocular area punctate (i=1–1.5d). Gena lineolate. Postgena imbricate. Mesoscutum polished, weakly imbricate medially. Mesoscutal punctation fine moderately sparse between parapsidal lines (i=1–3d), dense laterad of parapsidal line (i=1–1.5d), contiguous on anterolateral portion. Mesoscutellum similar to mesoscutum, submedial punctation sparse (i=3–6d). Axilla punctate. Metanotum weakly imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate. Mesepisternum punctate (i=1=1–2d). Metepisternum with dorsal third carinulate, ventral portion imbricate. Metapostnotum with coarse striae, interstitial areas polished, posterior margin imbricate. Propodeum with lateral surface imbricate with weak oblique striae, posterior surface imbricate-tessellate. Metasomal terga polished, punctation on basal halves moderately sparse (i=2–3d), sparse on apical halves (i=2– 4d).

Structure. Head very wide (length/width ratio = 0.78–0.81). Eyes weakly convergent below (UOD/LOD ratio = 1.06–1.10). Labrum enlarged and flattened, apical process without dorsal keel. Mandible large without preapical tooth. Clypeus 1/4 below suborbital tangent, apicolateral margins convergent. Antennal sockets moderately close (IAD/OAD <0.6). Frontal line carinate, ending 2 OD below median ocellus. IOD subequal to OOD. Gena much wider than eye. Pronotal dorsolateral angle acute. Pronotal ridge carinate. Mesoscutum overlapping pronotum medially. Basitibial plate lower carina present. Inner metatibial spur pectinate with 4 branches. Metapostnotum elongate (MMR ratio = 1.11–1.17), posterior margin rounded onto posterior surface. Propodeum with oblique carina virtually absent, lateral carina weak, not reaching dorsal margin. T5 medial specialized area reduced.

MALE. Unknown.

Range. New York ( Fig. 66 ).

Paratype. USA: NEW YORK: 1Ƥ Suffolk Co., Kalbfleisch Field Research Station, Huntington, 15.viii.1962 (P.H. Arnaud); [AMNH; AMNH_BEE00072844].

Floral records. ONAGRACEAE : Oenothera .

Etymology. The specific epithet is named for John S. Ascher in gratitude for providing me with the two specimens for study.

Barcode. Not available.

Comments. Rare. Lasioglossum ascheri is only known from two specimens collected 47 years apart. Lasioglossum ascheri is presumably a social parasite or cleptoparasite of nest-building Lasioglossum (Dialictus) .

Figures

FIGURE 66. Distribution map of Lasioglossum arantium (circles) and L. ascheri (squares).

FIGURE 67. Lasioglossum ascheri Gibbs female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 68. Lasioglossum ascheri Gibbs female, dorsal view of mesosoma.