Lasioglossum (Dialictus) coeruleum (Robertson)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 97-101

Lasioglossum (Dialictus) coeruleum (Robertson)

( Figures 90A–D , 91A–F )

Halictus coeruleus Robertson, 1893: 146 . ♀ ♂. Lectotype. ♀ USA, Illinois, Carlinville (C. Robertson); [INHS: 179,608] by W.E. LaBerge. Examined.

Taxonomy. Robertson, 1902: Chloralictus caeruleus , p. 248 (key); Viereck, 1916: Halictus (Chloralictus) caeruleus , p. 706; Michener, 1951: Lasioglossum (Chloralictus) coeruleum , p. 1113. (catalogue); Mitchell, 1960: Dialictus coeruleus ♂, p. 387 (redescription); Krombein, 1967: Lasioglossum (Dialictus) coeruleum , p. 463 (catalogue); Hurd, 1979: Dialictus coeruleus , p. 1965 (catalogue); Moure & Hurd, 1987: Dialictus coeruleus , p. 95 (catalogue); Pesenko et al., 2006: Evylaeus coeruleus , p. 6 (review).

Diagnosis. Both sexes of L. coeruleum are easily recognisable by their large size (5.3–7.1 mm) and deep metallic blue colouration (sometimes with green reflections) of the head, mesosoma and metasoma. Females have the subapical tooth of the mandible larger than in other species, nearly equal in size to the apical tooth. Males have distinct fine mesepisternal punctures.

Redescription. FEMALE. Length 5.25–7.10 mm; head length 1.58–1.82 mm; head width 1.70–1.99 mm; forewing length 4.64–5.00 mm.

Colouration. Head and mesosoma deep blue with occasional green or brassy reflections. Clypeus with apical 1/3 blackish brown. Antenna dark brown, flagellum with ventral surface dark brown. Tegula dark, reddish brown. Wing membrane subhyaline, venation and pterostigma reddish brown. Legs brown, medio- and distitarsi reddish. Metasomal terga blue, with greenish reflections, sterna brown, apical margins reddish brown.

Pubescence. Dull white. Sparse. Head and mesosoma with moderately sparse woolly hairs (1–1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Lower paraocular area and gena with sparse, appressed hairs. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2– 2.5 OD). Metasomal terga with sparse, fine setae. T1 acarinarial fan complete dorsally with widely spaced appressed hairs. T2–T4 with at most a few, scattered appressed hairs at basal margin.

Surface sculpture. Face weakly imbricate, punctation fine. Clypeus polished, basal margin imbricate, punctation sparse (i=1–3d). Supraclypeal area with punctation moderately sparse (i=1–2d). Lower paraocular and antennocular areas with punctation moderately dense (i=1–1.5d). Upper paraocular area and frons punctate-reticulate. Ocellocular area minutely punctate (i=d). Gena weakly lineolate. Postgena imbricate. Mesoscutum polished, weakly imbricate, punctation fine and deep, sparse medially (1–3d), moderately dense laterad of parapsidal lines (i≤1.5d) and dense on anterolateral portions (i<d). Mesoscutellum polished, punctation moderately sparse (i=1–2d). Axilla punctate. Metanotum ruguloso-imbricate. Preëpisternum rugose. Mesepisternum weakly rugulose, punctation obscure (i=1–2d), more distinct posteriorly. Metepisternum with dorsal third weakly striate and ventral portion imbricate. Metapostnotum incompletely striate, posterior margin imbricate. Propodeum with dorsolateral slope rugose, lateral and posterior surfaces imbricate. Metasomal terga weakly coriarious, punctation on basal halves close (i=1.5d), sparse on apical halves (except along premarginal line).

Structure. Head wide (length/width ratio = 0.92–0.93). Eyes weakly convergent below (UOD/LOD ratio = 1.17–1.23). Mandible subapical tooth nearly as long as apical tooth. Clypeus ½ below suborbital tangent, apicolateral margins weakly convergent. Antennal sockets close (IAD/OAD <0.5). Frontal line carinate, ending <2 OD below median ocellus. Gena wider than, or subequal to, eye. Inner metatibial spur pectinate with 3–5 teeth. Metapostnotum moderately elongate (MMR ratio = 1.26–1.33), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina moderately strong, lateral carina moderately strong, reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 6.71 mm; head length 1.76 mm; head width 1.81 mm; forewing length 4.94 mm.

Colouration. Head, mesosoma and metasoma bluish green. Flagellum with ventral surface yellowish brown. Tarsi brownish yellow.

Pubescence. Face below eye emargination with moderately dense tomentum, partially obscuring surface. Lower paraocular area with dense tomentum. Gena without tomentum. S2 apicomedial, S3 apical half, S4 lateral and S5 apicolateral portions with moderately dense plumose hairs.

Surface sculpture. Clypeal punctation moderately dense (i=1–2d). Mesepisternal punctation distinct (i=1– 2d). Metanotum rugulose. Metapostnotum completely rugoso-striate. Propodeum with dorsolateral slope and lateral and posterior surfaces rugose.

Structure. Head moderately wide (length/width ratio = 0.97). Eyes strongly convergent below (UOD/LOD ratio = 1.57). Clypeus 2/3 below suborbital tangent, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD> 1.7). Frontal line carinate, ending <2.5 OD below median ocellus. Pedicel shorter than F1. F2 length 2.0X F1. F2–F10 elongate (length/width ratio = 1.69–2.00). Metapostnotum moderately truncate (MMR ratio = 1.29), posterior margin sharply angled onto posterior surface.

Terminalia . S7 with median lobe clavate, sides concave, apex rounded. S8 with apicomedial margin weakly convex. Genitalia as in Fig. 91D–F . Gonobase with ventral arms widely separated. Gonostylus small, dorsal setae elongate. Retrorse lobes elongate, wide, attenuated and recurved apically.

Range. Ontario south to Georgia, west to Kansas ( Fig. 89 ).

Additional material examined. CANADA: ONTARIO: 1♀ Caledon East , woodlot clearing, 7.vii.1989 (L. Packer) ; 1♀ Manester Tract , St. Williams Co., N42°43´W080°26´, 12.[viii]– 1.ix.1992 (P.J. Carson) ; 1♀ Manester Tract , St. Williams Co., N42°43´W080°26´, 2–8.vi.1994 ; 1♂ Norfolk Co., 18.ix.2007 (A. Taylor) ; 1♀ York University Keel Campus, Boyer woodlot, 28.viii.2005 (E. Willis); [ PCYU] ; QUEBEC: 1♀ Gatineau Pk., Mountain Rd. , 12.vii.1965 (P.S. Corbet); [ PMAE] ; USA: DELAWARE: 3♀ New Castle Co., N39.3732 W05453, 19.vi.2004 (S.W. Droege); [ PCYU] ; GEORGIA: 2♀ Clarke Co., Sandy Creek Nat. Ctr., 16.iv.2007 (J. Haunla & S. Horn); [ PCYU] ; INDIANA: 1♀ Jasper Co., Stoutsburg , 27.vi.2001, 7:30, ( R. P. Jean) ; 1♀ Vigo Co., Landsbaum , 8.iv.2001, 9:00, ( R. P. Jean) ; MARYLAND: 4♀ 3.ix.2003 (S.W. Droege) ; 1♀ Anne Arundel Co., N39.07 W076.7765, 19.viii.2002 (L.E. Hilden) ; MASSACHUSETTS: 1♀ Middlesex Co., Groton: Snake Hill Field , 20.iv.2006 (M.F. Veit); [ PCYU] ; MICHIGAN: 1♀ Lapeer Co., N 43.13817 W83.21306, 30.vii.2009 (Tuell et al.); [ ARC] ; NEW YORK: 1♀ Hwy 15A, S of Rochester, N43.0485 W077.6184, 11.vi.2006 (j. Gibbs) ; 1♀ Orange Co., Cornwell, Black Rock Forest , 18 N4583180 E583761, 28.viii.2003 ( V. Giles & J. Rozen); [ PCYU] ; TEXAS: 1♀ Lamar Co., Camp Maxey , 24.v–1.vii.2003 (Godwin); [ CTMI]; VIR- GINIA: 1♀ Madison Co., N38.3793 N078.2672, 4– 6.vii.2003 (Petty) ; WEST VIRGINIA: 1♀ Grant Co., N39.2754 W079.2845, 12.viii.2007 (S.W. Droege); [ PCYU] .

Floral records. APIACEAE : Cryptotaenia canadensis , Daucus carota , Osmorhiza longistylis , ASTER- ACEAE: Solidago , Taraxacum , BRASSICACEAE : Alliaria petiolata , Arabis shortii , Barbarea , COMMELI- NACEAE: Tradescantia ohiensis ; FABACEAE : Melilotus , LAMIACEAE : Monarda , GROSSULARIACEAE : Ribes cynosbati , HYDROPHYLLACEAE : Hydrophyllum , PORTULACACEAE : Claytonia virginica , RANUNCULACEAE : Enemion biternatum , Hepatica nobilis var. acuta , ROSEACEAE: Amelanchier canadensis , Amelanchier , Crataegus , Malus , RUTACEAE : Zanthoxylum americanum .

Biology. Reinhard 1924: (predator, as D. caeruleus ); Knerer & Atwood, 1962b: (nest site, floral records); Stockhammer, 1967: (life history); Barrows, 1973: (induced soil nesting); Michener, 1974, pp. 274, 275: (nest site).

Comments. Uncommon. Nests in rotten logs ( Stockhammer 1967).

Figures

FIGURE 89. Distribution of Lasioglossum cephalotes (dark grey) and L. coeruleum (light grey).

FIGURE 90. Lasioglossum coeruleum (Robertson). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mandible. Scale bars, A–C = 1 mm.

FIGURE 91. Lasioglossum coeruleum (Robertson). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) ventral view of genital capsule; (E) dorsal view of genital capsule; (F) apical view of genital capsule. Scale bars, A–C = 1 mm, F = 0.5 mm.