Lasioglossum (Dialictus) oceanicum (Cockerell) 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 : 223-228

Lasioglossum (Dialictus) oceanicum (Cockerell) , new combination

( Figures 163A–D , 164A–F )

Halictus oceanicus Cockerell, 1916: 11 . ♀.

Holotype. ♀ USA, New Jersey, Ocean Grove , 12.vii.1893, [ NMNH: 27769]. Examined.

Dialictus advertus Mitchell, 1960: 433 . ♂. [new synonymy]

Holotype. ♂ USA, Massachusetts, Reading , 23.vii.1933 ( R. Dow); [ NCSU]. Examined.

Taxonomy. Robertson, 1902: Chloralictus nymphaearum , p. 248 (key); Viereck, 1916: Halictus (Chloralictus) nymphaearum , p. 706; Michener, 1951: Lasioglossum (Chloralictus) nymphaearum , p. 1115 (catalogue, synonymy); Mitchell, 1960: Dialictus nymphaearum ♂, p. 407 (redescription); Krombein, 1967: Lasioglossum (Dialictus) advertum , p. 462, L. (D.) nymphaearum , p. 465 (catalogue); Hurd, 1979: Dialictus advertus , p. 1963, D. nymphaearus , p. 1969 (catalogue); Moure & Hurd, 1987: Dialictus advertus , p. 102, D. nymphaearus , p. 116 (catalogue).

Diagnosis. Females of L. oceanicum can be recognised by the diagnostic combination of their large size (6.0– 7.5 mm), distally reflexed hypostomal carinae, coarse mesoscutal punctation (i=1–1.5d), strongly punctate ovoid tegula, strong and uninterrupted transverse carina delimiting dorsal and posterior surfaces of propodeum ( Fig. 163D ), and densely punctate apical impressed areas of metasomal terga. They are most similar to L. cressonii , L. albipenne , and L. bruneri which all lack strong punctures on the tegula and have medially interrupted transverse carinae on the propodeum.

Males of L. oceanicum are similar to females but have the hypostomal carina normal and the transverse carina of the propodeum distinctly bowed posteriorly ( Fig. 164D ). Males can be further distinguished by the dense facial tomentum that obscures the surface below the level of the eye emargination, moderately elongate head (length/width ratio = 0.97–1.00), and short flagellomeres (length/width ratio = 1.13–1.33). They are most similar to L. albipenne which lack distinct punctures on the tegula and have a longer head (length/width ratio = 0.99–1.08).

Redescription. FEMALE. Length 5.98–7.45 mm; head length 1.80–1.99 mm; head width 1.87–2.06 mm; forewing length 4.94–5.49 mm

Colouration. Head and mesosoma bluish green. Clypeus with apical half blackish brown. Antenna dark brown, flagellum with ventral surface reddish brown. Tegula dark reddish brown. Wing membrane subhyaline, venation and pterostigma brownish yellow. Legs brown, medio- and distitarsi reddish brown. Metasomal terga brown, faintly metallic blue, terga and sterna with apical margins translucent brownish yellow.

Pubescence. Dull white. Moderately 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 dense plumose hairs on lateral and posterior surfaces (2– 2.5 OD). Metasomal terga with moderately dense, fine setae. T1 acarinarial fan complete. T2 basolaterally and T3–T4 entirely with appressed tomentum partially obscuring disc. T2 apicolateral and T3–T4 apical margins with weak fringes.

Surface sculpture. Face imbricate, punctation coarse. Clypeus polished, punctation unevenly spaced (i=1– 3d). 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 finely punctate (i≤d). Gena and postgena striate. Mesoscutum polished, faintly imbricate medially, punctation coarse, moderately dense between parapsidal lines (i=1–1.5d), more widely spaced anteromedially (i=2.5d), reticulate laterad of parapsidal lines and on anterolateral portions. Mesoscutellum similar to mesoscutum, submedial punctation moderate sparse (i=1–3d). Axilla reticulate-punctate. Metanotum ruguloso-imbricate. Tegula distinctly punctate. Preëpisternum, hypoepimeral area, and mesepisternum rugose. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum with very strong, rugoso-striate. Propodeum with dorsolateral slope strongly rugose, lateral surface rugulose, posterior surface imbricate. Metasomal terga polished, punctation moderately sparse throughout (i=1–2.5d).

Structure. Head wide (length/width ratio = 0.95–0.96). Eyes convergent below (UOD/LOD ratio = 1.25– 1.28). Clypeus ½ below suborbital tangent, apicolateral margins convergent. Antennal sockets close (IAD/ OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. Gena narrower than eye. Hypostomal carinae parallel, reflexed distally, visible from lateral view. Inner metatibial spur pectinate with 4–5 teeth. Metapostnotum truncate (MMR ratio = 1.33–1.50). Propodeum with oblique carina strong, lateral carina complete, dorsal and posterior surfaces delimited by strong transverse carina.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length. 5.67– 6.83 mm; head length 1.63–1.80 mm; head width 1.68–1.80 mm; forewing length 4.45–4.88 mm

Colouration. Head and mesosoma more bluish. Mandible midlength with yellow-orange. Flagellum with ventral surface orange. Tarsi yellow to brownish yellow. Metasoma less metallic.

Pubescence. Face with dense white tomentum below level of eye emargination, lower paraocular area completely obscured, clypeus, supraclypeal area, upper paraocular area and frons partially obscured. S2–S3 apical halves and S4 apicolateral portions with subappressed plumose hairs (1–1.5 OD).

Surface sculpture. Metepisternum rugose-striate. Propodeum with lateral surface rugose, posterior surface rugulose. Metasomal terga with deep punctures, apical impressed areas impunctate except along anterior margin.

Structure. Head moderately wide to round (length/width ratio = 0.97–1.00). Eyes strongly convergent below (UOD/LOD ratio = 1.52–1.57). Antennal sockets distant (IAD/OAD> 1.2). Frontal line carinate, ending 2 OD below median ocellus. Pedicel shorter than F1. F2 length 1.30–1.58X F1. F2–F10 short (length/ width ratio = 1.13–1.33). Hypostomal carina not reflexed. Metapostnotum truncate (MMR ratio = 1.31–1.42), posterior margin strongly carinate.

Terminalia . S7 with median lobe strongly clavate, apex rounded ( Fig. 164E ). S8 with apicomedial margin weakly convex ( Fig. 164E ). Genitalia as in Fig. 164E–F . Gonobase with ventral arms widely separated. Gonostylus elongate, dorsal setae elongate. Retrorse lobe elongate, weakly attenuated, reflexed apically.

Range. Nova Scotia west to Ontario, Minnesota, south to North Carolina ( Fig. 165 ).

Additional material examined. CANADA: ONTARIO: 1♀ Caledon, Gschwendtner property, N43°48.89´W079°58.61´, 7.viii.2003 (J. Grixti) ; 1♀ Norfolk Co., Pterophylla Plant Nursery , N43°38.404 W080°34.379´, 13–22.viii.2006 (P.J. Carson) ; USA: ILLINOIS: 1♀ Kanakee Co., Hooper Br. , 2.vii.2003 ( R. P. Jean) ; INDIANA: 1♀ Newton Co., Conrad , 17.vii.2003 ( R. P. Jean) ; MARYLAND: 1♀ Pr. George’s Co., N39.0459 W076.7963, 1–2.viii.2002 (H.W. Ikerd) ; MASSACHUSETTS: 1♂ Middlesex Co., 2.5 mi NE of E. Pepperell, 5.viii.2006 (M.F. Veit) ; MICHIGAN: 2♀ Allegan Co., N42.5538 W086.0437, 28.viii.2003 (S.W. Droege); [ PCYU] ; 1♂ Barry Co., Yankee Springs Game Area , 15.vii.1960 (G.C. Eickwort); [ CUIC] ; 1♀ Tuscola Co., Silverwood Twp. , 18.vii.2008 (J.K. Tuell et al.); [ ARC] ; MINNESOTA: 1♀ Sher Co., Zimmerman, Sherburne NWR , 10.vii.2001 (S. Droege); MISSOURI: 1♀ Newton Co., Diamond Grove Pr. , 3.v.2003 (Arduser); [ PCYU] ; NEW YORK: 1♀ Suffolk Co., Gardiners Is. , 20.vii.2007 ( R. G. Goelet); [ AMNH] ; NORTH CAROLINA: 1♂ Blue Ridge Parkway, near Jefferson , N36.34234 W081.37465, 13.viii.2006 (J. Gibbs) ; RHODE ISLAND: 1♂ Newport Co., N41.4969 W071.3678, 22.vii.2005 (P. Ostenton); WEST VIR- GINIA: 1♀ Hampshire Co., N39.3348 W078.458, 20.ix. (S.W. Droege); [ PCYU] ; WISCONSIN: 1♀ Dane Co., Hauser Rd. ( R. A. Henderson); [ IRCW] .

Floral records. ANACARDIACEAE : Rhus , APIACEAE : Daucus , Taenidia , ASCLEPIADACEAE : Asclepias , ASTERACEAE : Anaphalis , Antennaria , Chrysanthemum , Hieracium , Krigia , Leontodon , Solidago , Taraxacum , BRASSICACEAE : Barbarea , Berteroa , CORNACEAE : Cornus , EUPHORBIACEAE : Euphorbia , FABACEAE : Lotus , Medicago , Melilotus officinalis , Trifolium , HYDRANGEACEAE : Hydrangea , IRIDACEAE : Sisyrinchium , LAMIACEAE : Pycnanthemum , LILIACEAE : Camassia , LYTHRACEAE : Lythrum , NELUMBONACEAE : Nelumbo , NYMPHAEACEAE : Castalia , POLYGONACEAE : Fagopyrum , PONTEDERIACEAE : Pontederia , RANUNCULACEAE : Ranunculus , ROSACEAE : Crataegus , Fragaria , Malus , Potentilla , Prunus , Rubus , SALICACEAE : Salix , VERBENACEAE : Lippia .

Biology. Bohart, 1941: (stylopization); Delfinado & Baker, 1976: (mite association).

Comments. Common.

The species redescribed here as L. oceanicum has typically been referred to as L. nymphaearum . The latter name is a replacement for Halictus palustris Robertson which is invalid due to primary homonymy with H. palustris Morawitz (1876) . The lectotype specimen for H. palustris Robertson belongs to the species L. albipenne which was originally described in the same paper (Robertson 1902). This is unfortunate because it is clear from the original description and from subsequent studies that L. nymphaearum has always been used to mean the species redescribed here as L. oceanicum . The name L. oceanicum , previously considered a junior synonym of L. nymphaearum , is resurrected.

The holotype specimen of Dialictus advertus seems to be an oddly sculptured L. oceanicum reminiscent of other anomalous Dialictus specimens (e.g. Knerer & Atwood 1964; Hopwood 2007; Gibbs 2010). The ventral portion of the mesepisternum has distinct punctures and the propodeum lacks the well-defined transverse carina. In all other respects it matches a typical L. oceanicum including the diagnostic punctate ovoid tegula.

Figures

FIGURE 163. Lasioglossum oceanicum (Cockerell). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) metapostnotum. Scale bars, A–C = 1 mm.

FIGURE 164. Lasioglossum oceanicum (Cockerell). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) metapostnotum; (E) ventral view of genital capsule, S7, S8; (F) dorsal view of genital capsule. Scale bars, A–C = 1 mm, F = 0.5 mm.

FIGURE 165. Distribution of Lasioglossum oceanicum (light grey), L. pacatum (medium grey), and L. packeri (dark grey).