Lasioglossum (Dialictus) platyparium (Robertson)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 261-265

Lasioglossum (Dialictus) platyparium (Robertson)

( Figures 184A–D , 185A–E )

Halictus platyparius Robertson, 1895: 117 . ♀. Lectotype. ♀ USA, Illinois, Carlinville (C. Robertson); [INHS: 179,614] by W.E. LaBerge .. Examined.

Taxonomy. Robertson, 1901: Paralictus platyparius , p. 229 (generic description); Michener, 1951: Lasioglossum (Paralictus) platyparium , p. 1119 (catalogue); Mitchell, 1960: Paralictus platyparius ♂, p. 448 (redescription); Krombein, 1967: Lasioglossum (Paralictus) platyparium , p. 467 (catalogue); Paralictus platyparius , p. 1974 (catalogue); Moure & Hurd, 1987: Paralictus platyparius , p. 143 (catalogue).

Diagnosis. See the diagnosis for L. asteris .

Redescription. FEMALE. Length 4.58–5.80 mm; head length 1.39–1.51 mm; head width 1.63–1.80 mm; forewing length 3.48–3.84 mm

Colouration. Head and mesosoma very dull metallic bluish green. Antenna dark brown, flagellum with ventral surface reddish brown. Tegula dark reddish brown to dark amber. Wing membrane dusky, venation and stigma dark amber. Legs brown, medio- and distitarsi reddish brown. Metasoma dark brown, terga and sterna with apical margins translucent brownish yellow.

Pubescence. Dull white. Sparse throughout. Head and mesosoma with moderately sparse woolly hairs (1– 1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Face without appressed hairs. Pronotal collar without dense tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Mesofemoral and mesotibial combs dense but short relative to non-parasitic species. Metafemoral scopa reduced relative to nest-building species, only a few elongate hairs curving above ventral surface. Penicillus greatly reduced, indistinguishable from other hairs. Metasoma with moderately sparse, fine setae. T1 acarinarial fan sparse, incomplete with dorsal opening greater than width of lateral appressed hair patches. T2–T3 basolaterally and T4 entirely with very sparse tomentum. Sternal hairs erect, posteriorly directed (2–3 OD). T2 apicolateral and T3–T4 apical margins with very sparse fringes.

Surface sculpture. Face polished, weakly imbricate, punctation fine. Clypeal punctation sparse (i=1–5d). Supraclypeal, lower paraocular and antennocular areas with punctation moderately sparse (i=1–3d). Upper paraocular area and frons punctation dense (i≤d). Ocellocular area punctate (i=1–1.5). Gena faintly lineolate. Postgena faintly imbricate. Mesoscutum weakly imbricate, more polished posteriorly, punctation sparse between parapsidal lines (i=1–4d), moderately sparse laterad of parapsidal lines (i=0.5–1.5d) and dense on anterolateral portions (i≤d). Mesoscutellum polished, submedial portion virtually impunctate. Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate. Mesepisternum dorsal half weakly rugulose, ventral half imbricate. Metepisternum dorsal half rugoso-striate, ventral half imbricate. Metapostnotum with longitudinal striae not reaching posterior margin, posterior surface imbricate. Propodeum with dorsolateral slope and lateral surface imbricate, posterior surface tessellate. Metasomal terga polished except apical impressed areas faintly coriarious, punctation on basal halves (i=1–1.5d), apical half obscurely punctate (i=1.5–2.5d).

Structure. Head enormous, very wide (length/width ratio = 0.84–0.85). Eyes weakly convergent (UOD/ LOD ratio = 1.07–1.09). Labrum enlarged and flattened with distinct basal tubercle, apical process without dorsal keel. Mandibles large, scythe-like, with minute subapical angle. Clypeus 1/3 below suborbital tangent, apicolateral margins widely convergent. Antennal sockets distant (IAD/OAD> 0.75). Frontal line carinate, ending 2.5 OD below median ocellus. IOD subequal to OOD. Gena huge, 1.5 times as wide as eye. Pronotal dorsolateral angle acute. Pronotal ridge uninterrupted. Basitibial plate with posterior carina weak. Inner metatibial spur pectinate with 3–4 short teeth. Metapostnotum truncate (MMR ratio = 1.32–1.43), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina very weak, lateral carina weak, not reaching dorsal margin. T5 medial specialized area reduced in size relative to non-parasitic species.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.64– 5.25 mm; head length 1.30–1.42 mm; head width 1.34–1.44 mm; forewing length 2.93–3.66 mm.

Colouration. Labrum, mandible, flagellum ventral surface, Tibial bases and apices, and tarsi yellow to brownish yellow.

Pubescence. Face below eye emargination with sparse tomentum, partially obscuring lower paraocular area, nearly absent from clypeus and supraclypeal area. S2–S5 lateral portions with moderately spare plumose hairs (1–1.5 OD).

Surface sculpture. Lower paraocular and supraclypeal areas densely punctate (i≤d). Frons reticulate, punctation moderately sparse between parapsidal lines (i=1–2.5d), dense laterad of parapsidal lines and on anterolateral portions (i≤d). Ventral mesepisternum sometimes obscurely punctate. Metapostnotum crescentic, completely rugoso-striate. Propodeum with dorsolateral slope and posterior surface rugulose. Metasomal terga distinctly punctate (i=1–2d), apical impressed margin impunctate.

Structure. Head wide (length/width ratio = 0.95–0.96). Eyes strongly convergent below (UOD/LOD ratio = 1.33–1.41). Clypeus 2/3 below suborbital tangent, apicolateral margins convergent. Antennal sockets distant (IAD/OAD> 1.1). Frontal line carinate, ending 2 OD below median ocellus. IOD subequal to OOD. Pedicel subequal to F1. F2 length 1.6–1.7X F1. F2–F10 moderately short (length/width ratio = 1.25–1.42). Pronotum dorsolateral angle orthogonal. Metapostnotum moderately elongate (MMR ratio = 1.08–1.30), posterior margin sharply angled onto posterior surface.

Terminalia . S7 with median lobe widely acuminate, apex rounded ( Fig. 185D ). S8 with apicomedial margin weakly convex ( Fig. 185D ). Genitalia as in Fig. 185D–E . Gonobase with ventral arms narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobe wide, moderately elongate, weakly attenuated apically.

Range. Ontario south to Georgia, Louisiana and west to Minnesota ( Fig. 186 ).

Additional material examined. USA: DISTRICT OF COLUMBIA: 1♂ N38.87972 W077.033, 4– 5.x.2004 (E. Keto) ; 2♀♀ N38.8883 W077.045, 6–7.x.2004 (E. Keto); 2♂ N38.895 W077.04583, 6–7.x.2004 (E. Keto); 3♂ N38.886 W077.03416, 18–19.x.2004 (E. Keto); 1♂ N38.886 W077.03694, 18–19.x.2004 (E. Keto); [ PCYU] ; GEORGIA: 1♀ Jasper Co., Oconee N.F., 16.v.2008 (J. Hanula & S. Horn); [ JHRC]; MARY- LAND: 3♀♀ Anne Arundel Co., N38.858 W76.6866, 2.iv.2002 (S.W. Droege) ; 1♀ Pr. George’s Co., N39.037 W076.8719, 18–19.iv.2006 (Riegel & Walker) ; 1♀ Pr. George’s Co., N39.0294 W076.9268, 22.viii.2004 (N. Allen) ; NORTH CAROLINA: 1♂ Junaluska Meadow , N35.54289 W082.9566, 7.viii.2006 (J. Gibbs) ; WEST VIRGINIA: 1♀ Jefferson Co., Shepherdstown National Conservation Training Center , 7.iv.1999 (S. Droege); [ PCYU] ; WISCONSIN: 1♂ Marinette Co., N45.2441 W87.81875, 28.vii.2005 (J. Watson); [ ARC] .

Floral records. ANACARDIACEAE : Rhus , APIACEAE : Zizia aurea , ASCLEPIADACEAE : Cynanchum laeve , ASTERACEAE : Erigeron , Gnaphalium “ polycephalum ”, Solidago nemoralis , Symphyotrichum pilosum , S. lateriflorum , S. ericoides , Taraxacum , CUCURBITACEAE : Cucurbita , LAMIACEAE : Pycnanthemum , RUTACEAE : Zanthoxylum americanum , SALICACEAE : Salix cordata .

Comments. Uncommon. This is a parasitic species. Host species unknown. No Canadian material has been examined. A specimen from New York state has been reported ( Fetridge et al. 2008). This in combination, with the material from Wisconsin, make the occurrence of this species in Ontario seem likely.

Figures

FIGURE 184. Lasioglossum platyparium (Robertson). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mandible. Scale bars, A–C = 1 mm.

FIGURE 185. Lasioglossum platyparium (Robertson). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) ventral view of genital capsule, S7, S8; (E) dorsal view of genital capsule. Scale bars, A–C = 1 mm, E = 0.5 mm.

FIGURE 186. Distribution of Lasioglossum platyparium (light grey) and L. prasinogaster (dark grey).