Lasioglossum (Dialictus) oblongum (Lovell)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 211-215

Lasioglossum (Dialictus) oblongum (Lovell)

( Figures 156A–D , 157A–F )

Halictus oblongus Lovell, 1905a: 40 . ♀ ♂. Type locality.? Maine, 24.viii? [depository unknown]

Taxonomy. Lovell, 1905a: Halictus versans ♂, p. 39 (misdet.); Lovell, 1908: Halictus (Chloralictus) oblongus ♂, p. 38 (description); Michener, 1951: Lasioglossum (Chloralictus) oblongum , p. 1115 (catalogue); Mitchell, 1960: Dialictus oblongus ♂, p. 409 (redescription); Krombein, 1967: Lasioglossum (Dialictus) oblongum , p. 465 (catalogue); Hurd, 1979: Dialictus oblongus , p. 1969 (catalogue); Moure & Hurd, 1987: Dialictus oblongus , p. 116 (catalogue).

Diagnosis. Females of L. oblongum can be recognised by the diagnostic combination of a bluish green head and mesosoma, round head (length/width ratio = 0.94–0.95), densely punctate supraclypeal area (i≤d), imbricate mesoscutum with moderately sparse punctures on central disc (i=1–2d), weakly rugose mesepisternum, metapostnotum very coarsely striate ( Fig. 23A ), T1 acarinarial fan with wide dorsal opening, and metasomal terga polished with virtually no appressed tomentum ( Fig. 156D ). They are similar to L. marinense which have the metapostnotum rugoso-striate.

Males of L. oblongum are similar to females but may be further distinguished by the moderately elongate head (length/width ratio = 0.98–1.01), moderately elongate flagellomeres (length/width ratio = 1.54–1.58), metapostnotum with coarse longitudinal rugae that reach the posterior margin and are separated by wide and distinctly shining areas ( Figs. 57A , 157D ), and moderately dense plumose hairs on the apicolateral portions of S3–S5.

Redescription. FEMALE. Length 4.91–6.61 mm; head length 1.46–1.63 mm; head width 1.54–1.73 mm; forewing length 3.90–4.39 mm.

Colouration. Head and mesosoma bluish green to deep blue. Clypeus with apical half blackish brown and basal half, and supraclypeal area greenish. Antenna dark brown, flagellum with ventral surface reddish brown to brownish yellow. Tegula translucent reddish brown. Wing membrane subhyaline, venation and pterostigma dark amber. Legs dark brown, medio- and distitarsi reddish. Metasoma blackish brown, terga and sterna with apical margins reddish to brownish yellow.

Pubescence. Dull white. Very sparse. Head and mesosoma with moderately dense woolly hairs (1–1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Lower paraocular area and gena without subappressed tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with sparse, fine setae, virtually no appressed tomentum, at most a few obscure appressed hairs basolaterally. T1 acarinarial fan incomplete, dorsal opening wider than lateral patches.

Surface sculpture. Face imbricate, punctation fine, shallow. Clypeus polished, punctation moderately sparse (i=1–2d). Supraclypeal area with punctation dense (i≤d). 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 obscurely punctate (i≤d). Gena weakly lineolate. Postgena weakly imbricate. Mesoscutum imbricate-tessellate, punctation moderately sparse between parapsidal lines (i=1–2), dense laterad of parapsidal lines (i≤d), contiguous on anterolateral portions. Mesoscutellum similar to mesoscutum, submedial punctation sparse (i=1–4d). Axilla punctate. Metanotum rugulose. Preëpisternum rugose. Hypoepimeral area rugose. Mesepisternum dorsal portion weakly rugose and ventral portion rugulose. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum strongly striate. Propodeum with dorsolateral slope rugose, lateral surface rugulose, posterior surface imbricate. Metasomal terga polished except anterior and posterior margins weakly coriarious, punctation on basal halves moderately sparse (i=1–2d), sparse on apical halves (i=2–5d).

Structure. Head wide (length/width ratio = 0.94–0.95). Eyes convergent below (UOD/LOD ratio = 1.21– 1.26). Clypeus 1/3–1/2 below suborbital tangent, apicolateral margins. 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 3–5 teeth. Metapostnotum moderately elongate (MMR ratio = 1.17–1.27), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina weak, lateral carina moderately strong, almost reaching dorsal surface.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.51– 5.49 mm; head length 1.39–1.50 mm; head width 1.42–1.49 mm; forewing length 3.84–3.97 mm

Colouration. Flagellum with ventral surface brown. Tegula reddish brown. Wing membrane dusky, venation and pterostigma reddish brown. Tarsi reddish brown. Metasomal terga blackish.

Pubescence. Face below antennal sockets with scattered appressed tomentum, partially obscuring surface. Lower paraocular area with moderately dense tomentum obscuring surface. S3–S5 apicolateral portions with moderately dense plumose hairs.

Surface sculpture. Metanotum rugose. Metapostnotum very strongly rugoso-striate. Metapostnotum coarsely rugoso-striate, interstitial areas wide and shining. Propodeum with dorsolateral slope and lateral and posterior surfaces rugose. Metasomal terga impunctate on posterior half (except along premarginal line).

Structure. Head round (length/width ratio = 0.98–1.01). Eyes strongly convergent below (UOD/LOD ratio = 1.50–1.63). Clypeus 1/2 below suborbital tangent, apicolateral margins convergent. Antennal sockets distant (IAD/OAD> 1.3). Frontal line carinate, ending 2 OD below median ocellus. Pedicel subequal to F1. F2 length 1.9X F1. F2–F10 moderately elongate (length/width ratio = 1.54–1.58). Metapostnotum moderately elongate (MMR ratio = 1.23–1.32), posterior margin sharply angled onto posterior surface.

Terminalia . S7 with median lobe narrowly clavate, sides subparallel, apex rounded. S8 with apicomedial margin weakly convex. Genitalia as in Fig. 157E–F . Gonobase with ventral arms narrowly separated. Gonostylus moderately large, dorsal setae elongate. Retrorse lobe elongate, weakly attenuated, recurved apically.

Range. Quebec, Ontario, south to Virginia, east to Massachusetts ( Fig. 155 ).

Additional material examined. CANADA: ONTARIO: 1♀ Claireville, Woodbridge , 1.x.1977 (P.E. Hallet); [ PHPC] ; 1♀ Lambton Co., N43°15.317´W081°49.867´, 20.vi.2008 (A. Taylor) ; NOVA SCOTIA: 2♂♂ Kings Co., East Torbrook , N44.9266 W064.9301, 4.x.2001 (C. Sheffield) ; 1♀ Kings Co., Lockhartville , N45.0850 W064.2337, 13.vi.2002 (C. Sheffield); [ PCYU] ; QUEBEC: 1♀ Gatineau Pk., Mountain Rd. , 12.vii.1965 (P.S. Corbet); [ PMAE] ; USA: DISTRICT OF COLUMBIA: 1♀ Washington, N38.9113 W076.9519, 6–7.vii.2004 (C. Osborn) ; INDIANA: 1♂ Porter Co., Indiana Dunes N.L., Howe’s Prairie , N41°39´09´´ W087°04´15´´, 31.viii.2004 ( R. Grundel) ; MARYLAND: 3♀ Montgomery Co., N38.97 W077.1565, 24.vi.2006 (S.W. Droege) ; 1♀ Pr. George’s Co., N39.0478 W076.7952, 31.vii.2002 (H.W. Ikerd) ; MASSACHUSETTS: 1♀ Middlesex Co., Pepperell, Nissitisit Riv. , 5.viii.2006 (M.F. Veit) ; 1♂ Worcester Co., Winchendon, Lk Denison Rec. Area , 21.vii.2006 (M.F. Veit) ; VIRGINIA: 3♀ Assateague I., N37.9144 W075.3379, 30.vi–1.vii.2006 (S.W. Droege) ; 1♀ Assateague I., N37.9804 W075.2926, 30.vi–1.vii.2006 (S.W. Droege) ; 1♀ Assateague I., N37.8904 W075.3402, 1–2.vii.2006 (S.W. Droege) ; WISCONSIN: 1♂ Iowa Co., Avoca Prairie , N43.19501 W090.28733, 23.vii.2006 (A. Wolf); [ PCYU] .

Floral records. Due to the resurrection of L. planatum (below), the list of floral records taken from the literature are likely to apply in part to both. Records marked with an asterisk have been verified for L. oblongum . APIACEAE : Zizia , ASCLEPIADACEAE : Asclepias , ASTERACEAE : Eupatoriadelphus maculatus *, Eupatorium , Rudbeckia , Solidago *, Taraxacum , BRASSICACEAE : Brassica , FABACEAE : Melilotus , HYDROPHYLLACEAE : Hydrophyllum , LILIACEAE : “ Smilacina ”, LYTHRACEAE : Lythrum *, NYMPHAEACEAE : Castalia , PONTEDERIACEAE : Pontederia *, RANUNCULACEAE : Aquilegia , Enemion biternatum , ROSACEAE : Aruncus , Prunus , SCROPHULARIACEAE : Penstemon, UNCERTAIN PLACEMENT : “ Gerardia ”.

Biology. Evans & Lin, 1959: (predator); Sakagami & Michener, 1962, pp. 14: (nesting substrate).

Comments. Uncommon. The location of the type specimen is unknown. The type depository is listed as “ Washington ” in Moure and Hurd (1987) but was not found among the NMNH types, nor is it listed among their type specimens. Lovell may not have designated a holotype as several of his other species have lectotypes designated by later authors. Multiple species could potentially match Lovell’s (1905) original description of Halictus oblongus . When Lovell (1908) synonymized H. oblongus with H. planatus he wrote: “Only a single specimen of H. oblongus ♀ has been taken… it differs from H. planatus in some minor characters…the bee described as H. planatus are common”. The form I have chosen seems to correspond with that of Mitchell (1960) and differs from L. planatum (see below).

Figures

FIGURE 23. Metapostnotum of female (A) L. oblongum, (B) L. planatum.

FIGURE 57. Mesoscutal surface between punctures (A) tessellate, (B) polished.

FIGURE 155. Distribution of Lasioglossum novascotiae (light grey and star) and L. oblongum (dark grey).

FIGURE 156. Lasioglossum oblongum (Lovell). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) metasomal terga. Scale bars, A–C = 1 mm.

FIGURE 157. Lasioglossum oblongum (Lovell). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) metapostnotum; (E) ventral view of genital capsule; (F) dorsal view of genital capsule. Scale bars, A–C = 1 mm, F = 0.5 mm.