Lasioglossum (Dialictus) achilleae (Mitchell)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 49-50

Lasioglossum (Dialictus) achilleae (Mitchell)

( Figure 62A–D )

Dialictus achilleae Mitchell, 1960: 377 . ♀. Holotype. ♀ USA, North Carolina, Cruso , June 25, 1934, on Achillea, (T.B. Mitchell) ; [NCSU]. Examined.

Taxonomy. Krombein, 1967: Lasioglossum (Dialictus) achilleae , p. 462 (catalogue); Hurd, 1979: Dialictus achilleae , p. 1963 (catalogue); Moure & Hurd, 1987: Dialictus achilleae , p. 87.

Diagnosis. Females of L. achilleae can be recognised by the diagnostic combination of a small size (4.27– 5.06 mm), wide head (length/width ratio = 0.92), polished mesoscutum due to weak microsculpture with sparse punctation even laterad of the parapsidal lines and strong oblique carinae of the propodeum. The Eastern USA species L. apopkense (Robertson) is most similar but has the mesoscutum distinctly dull due to microsculpture. Lasioglossum apopkense only occurs as far north as the Pine Barrens of New Jersey (personal observation).

Male unknown.

Redescription. FEMALE. Length 4.27–5.06 mm; head length 1.32–1.37 mm; head width 1.44–1.49 mm; forewing length 3.72–3.78 mm.

Colouration. Head and mesoscutum pale bluish green to pale green. Mandible dark orange. Clypeus with apical half blackish brown. Antenna dark brown, flagellomeres with ventral surface reddish brown. Mesoscutum with anteromedial area brassy. Propodeum with dorsal surface blue. Tegula amber. Wing membrane hyaline with pale setae, venation and pterostigma pale whitish yellow. Legs brown, metabasitarsus infused with dark amber. Metasoma brown, terga and sterna with apical margins reddish brown, T3–T4 apical margins translucent yellow.

Pubescence. Dull white. Mostly sparse. Head and mesosoma with sparse woolly hairs (1–2 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Lower paraocular area with tomentum. Gena with sparse tomentum. Propodeum with plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with sparse, fine setae. T1 acarinarial fan sparse with wide dorsal opening, equal to width of lateral fan. T2–T3 basolaterally and T4 entirely with very sparse tomentum.

Surface sculpture. Face polished, weakly imbricate, punctation moderately fine. Clypeus polished, punctation sparse (i=1–3d). Supraclypeal area with punctation sparse (i=3–5d). Lower paraocular area punctation dense (i<d). Antennocular area punctation moderately sparse (i=0.5–2d). Upper paraocular area and frons punctation moderately dense (i≤1.5d). Gena polished, finely punctate. Postgena imbricate. Mesoscutum polished and shining, anteromedial area weakly tessellate, punctation deep and moderately sized, sparse throughout (i=1–4d), moderately sparse laterad of parapsidal line (i=2d) and anterolateral area (i=1–2d). Mesoscutellum similar to mesoscutum, submedial area impunctate. Axilla punctate. Metanotum rugulose. Preëpisternum rugose. Hypoepimeral area rugose. Mesepisternum rugose dorsally, ventral half rugulosoimbricate with obscure punctation (i=1–2d). Metepisternum rugose on dorsal two-thirds. Metapostnotum coarsely rugoso-striate, interstitial areas polished and shining. Propodeum with dorsolateral slope coarsely rugoso-striate, lateral surface ruguloso-tessellate, posterior surface strongly tessellate. Metasomal terga polished except apical impressed areas coriarious. T1 largely impunctate. T2–T4 punctation sparse basally (i=1– 3d), apical half impunctate (except along premarginal line).

Structure. Head wide (length/width ratio = 0.92). Eyes weakly convergent below (UOD/LOD ratio = 1.22–1.23). Clypeus 1/3 below suborbital tangent, apicolateral margins convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. Eye wider than gena. Parapsidal and medial lines deep. Inner metatibial spur pectinate with 3 teeth. Metapostnotum moderately elongate (MMR ratio = 1.08–1.24), posterior margin carinate, separated from posterior surface. Propodeum with dorsolateral slope delimited below by strong oblique carina forming an obtuse angle, lateral carina strong, reaching dorsal margin.

MALE. Unknown

Range. Southern Ontario south to Georgia ( Fig. 61 ).

Additional material examined. CANADA: ONTARIO: 1♀ Hald.- Norfolk Reg., Manester Tract , 6 km NNW St. Williams, along forest trail, white pans, 2.viii.2001, (Buck & Parchami-Araghi); [ DEBU] ; 1♀ Manestar Tract, St. Williams , N42°43ʹ W80°26ʹ, 2–8.vi.1994 (P.J. Carson); [ PCYU] ; USA: GEORGIA: 1♀ Rabun Co., Rabun Bald , 13.vii.1957 (J.G. Chilcott); [ CNC] ; MASSACHUSETTS: 1♀ H. cressonii paratype; [ ANSP] .

Floral records. ASTERACEAE : Achillea , RHAMNACEAE : Ceanothus , HYDRANGEACEAE : Hydrangea .

Comments. Rare. New record for Canada.

Figures

FIGURE 61. Distribution of Lasioglossum abundipunctum (light grey) and L. achilleae (dark grey).

FIGURE 62. Lasioglossum achilleae (Mitchell). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) metapostnotum and propodeum. Scale bars, A–C = 1 mm.