Lasioglossum (Dialictus) imitatum (Smith)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 156-161

Lasioglossum (Dialictus) imitatum (Smith)

( Figures 125A–D , 126A–F)

Halictus imitatus Smith, 1853: 71 . ♂.

Holotype. ♂ North America [ BMNH: B.M. type 17a 999]. Examined.

Halictus inconspicuus Smith, 1853: 73 . ♀.

Holotype. ♀ North America [ BMNH: B.M. type 17a 1007]. Examined.

Halictus stultus Cresson, 1872: 254 . ♀.

Holotype. ♀ USA, Texas, Bosque Co., (G.W. Belfrage); [ ANSP]. Examined.

Chloralictus sparsus Robertson, 1902: 249 . ♀ ♂.

Halictus hortensis Lovell, 1905 a: 39 . ♀.

Lectotype. ♀ USA, Maine, Waldoboro , on “cultivated blackberry”, 19.vi, (Lovell); [ NMNH: 71568] by T. B. Mitchell. Examined.

Halictus (Chloralictus) insolitus Sandhouse, 1924: 41 . ♂. [new synonymy]

Holotype. ♂ USA, Iowa, Vinton , 23.vi.1922 [ NMNH: 26446]. Examined.

Dialictus lectus Mitchell, 1960: 438 . ♂. [new synonymy]

Holotype. ♂ USA, Georgia, Kennesaw Mt. , 1.ix.1946, [ NCSU]. Examined.

Taxonomy. Cockerell, 1905: Halictus inconspicuus ♂, p. 349, H. imitatus ♀, p. 350 (tax. notes); Lovell, 1908: Halictus hortensis ♂, p. 39 (description); Viereck, 1916: Halictus (Chloralictus) sparsus , p. 706 (key); Michener, 1951: Lasioglossum (Chloralictus) imitatum , p. 1114, L. (C.) inconspicuum , p. 1114, L. (C.) insolitum , L. (C.) sparsum , p. 1027 (catalogue, synonymy); Michener, 1953: Lasioglossum (Chloralictus) sparsum , p. 1027 (larva); Krombein, 1958: Lasioglossum (Chloralictus) inconspicuum , p. 230, (catalogue); Mitchell, 1960: Dialictus imitatus ♂, p. 400, D. inconspicuous ♀, p. 400 (redescription); Knerer and Atwood, 1962: D. imitatus , p. 168 (synonymy); Krombein, 1967: Lasioglossum (Dialictus) imitatum , p. 464; L. (D.) lectum , p. 464 (catalogue); Hurd, 1979: Dialictus imitatus , p. 1967, D. insolitus , p. 1967, D. lectus , p. 1968 (catalogue); Moure & Hurd, 1987: Dialictus imitatus , p. 105, D. insolitus , p. 109, D. lectus , p. 110 (catalogue); Pesenko et al., 2000: Evylaeus imitatus , p. 46 (review).

Diagnosis. Females of L. imitatum can be distinguished from all other Canadian Dialictus by the distinct coarse setae on T3–T4 ( Fig. 125D ). They may be further recognised by their small size (3.4–5.0 mm), gena wider than eye, parallel hypostomal carinae, fine punctures and weak sculpturing throughout. They are most similar to L. heterognathum and L. fattigi which both lack coarse setae on T3–T4. Female L. heterognathum have divergent hypostomal carinae.

Males of L. imitatum can be recognised by their small size (4.2–4.3 mm), moderately elongate head (length/width ratio = 1.00–1.02), moderately sparse tomentum on face only dense on lower paraocular area, weakly imbricate mesoscutum with fine punctures that are sparse on the central disc (i=1.5–2.5d), obscure punctures on the hypoepimeral area and ventral mesepisternum, weakly angled posterior margin of the metapostnotum, and impunctate apical impressed areas of the metasomal terga.

Redescription. FEMALE. Length 3.36–5.00 mm; head length 1.01–1.32 mm; head width 1.13–1.42 mm; forewing length 2.87–3.60 mm.

Colouration. Head and mesosoma pale green. Clypeus with apical half blackish brown and basal half, and supraclypeal area with brassy reflections. Antenna dark brown, flagellum with ventral surface reddish brown to orange. Tegula amber. Wing membrane subhyaline, venation and pterostigma pale amber. Legs brown, tibial bases and apices and tarsi orange-yellow. Metasoma dark brown, terga and sterna with apical impressed areas translucent brownish yellow.

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 scattered tomentum not obscuring surface. Propodeum with moderately sparse plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with sparse, fine setae, without appressed tomentum. T1 acarinarial fan of appressed hairs with wide dorsal opening. T3–T4 sparsely and uniformly covered with coarse, simple setae (1–1.5 OD).

Surface sculpture. Face imbricate, punctation fine, shallow. Clypeus with apical half polished, punctation sparse (i=1.5–3d). Supraclypeal area with punctation moderately dense (i=1–1.5d). Lower paraocular and antennocular areas with punctation moderately dense (i=1–1.5d). Upper paraocular area, frons and ocellocular area punctation dense (i≤d). Gena polished. Postgena imbricate or lineolate. Mesoscutum imbricate, punctation fine, moderately sparse between parapsidal lines (i=1.5–2.5d), dense laterad of parapsidal line (i=d) and on anterolateral portion (i≤d). Mesoscutellum similar to mesoscutum, submedial punctation sparse (i=2–5d). Axilla minutely punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate. Mesepisternum dorsal half weakly rugulose, ventral half imbricate. Metepisternum with dorsal half weakly ruguloso-striate, ventral half imbricate. Metapostnotum weakly and incompletely striate, posterior margin imbricate. Propodeum with dorsolateral slope imbricate, lateral and posterior surfaces tessellate. Metasomal terga coriarious, punctation on basal halves sparse (i=1.5–3d), apical halves impunctate (except along premarginal line).

Structure. Head quadrate, very wide (length/width ratio = 0.88–0.95). Eyes weakly convergent below (UOD/LOD ratio = 1.18–1.19). Clypeus 1/2 below suborbital line, apicolateral margins convergent. Antennal sockets distant (IAD/OAD = 0.5). Frontal line carinate, ending weak <2 OD below median ocellus. Gena wider than, or equal to, eye. Inner metatibial spur pectinate with 2–3 teeth. Metapostnotum moderately elongate (MMR ratio = 1.10–1.28), posterior margin rounded onto posterior surface. Propodeum with oblique carina virtually absent, lateral carina weak, reaching ½ distance to dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.21– 4.33 mm; head length 1.15–1.27 mm; head width 1.13–1.27 mm; forewing length 2.99–3.17 mm.

Colouration. Flagellum with ventral surface reddish. Tegula reddish brown. Meso- and metatarsi yellow.

Pubescence. Lower paraocular area with dense tomentum obscuring most of surface. Clypeus, supraclypeal area and lower frons with scattered tomentum partially obscuring surface. T3–T4 without distinctive pubescence. Sterna sparsely pubescent, S2–S4 apically with subappressed hairs.

Surface sculpture. Lower mesepisternum obscurely punctate. Metapostnotum coarsely rugoso-striate.

Structure. Head moderately elongate (length/width ratio = 1.00–1.02). Eyes more strongly convergent below (UOD/LOD ratio = 1.57–1.67). Antennal sockets distant (IAD/OAD> 1.1). Frontal line carinate, ending weak 2.5 OD below median ocellus. Pedicel subequal to F1. F2 length 1.8X F1. F2–F10 moderately elongate (length/width ratio = 1.42–1.60). Metapostnotum moderately elongate (MMR ratio = 1.11–1.28), posterior margin weakly angled onto posterior surface.

Terminalia . S7 with median lobe narrowly clavate, apex rounded. S8 with apicomedial margin weakly convex. Genitalia as in Fig. 126E–F. Gonobase with ventral arms narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobes narrow, attenuated apically.

Range. Nova Scotia west to Alberta, south to Florida and west to California ( Fig. 124 ).

Figure 126. Lasioglossum imitatum (Smith) . 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.

Additional material examined. CANADA: MANITOBA: 12♀♀ Willow Bend , 20.vi.1968 ( T. Harcus); [ ROM] ; NOVA SCOTIA: 4♀♀ Annapol. Co., Melvern Sq. , N44.9892 W064.9971, 12.vi.2001 (C. Sheffield) ; 8♀♀ Kings Co., Avonport , N45.1198 W064.273, 1.viii.2002 (C. Sheffield) ; ONTARIO: 1♀ Toronto, Ulster , N43.659 W079.413, 23.ix.2006 (J. Gibbs); [ PCYU] ; QUEBEC: 10♀♀ Gatineau Pk., Mountain Rd. , 12.vii.1965 (P. S. COrbet); [ PMAE] ; SASKATCHEWAN: 2♀♀ N of Rocanville, Qu’Appelle R ., N50.5084 W101.7416, 454 m, 2.vi.2007 (Goulet, Boudreault & Fernandez); [ CNC] ; USA: ALABAMA: 6♀ 10♂ Clay Co., Clairmont Springs Baptist Ch. , 16S N3691367 E599888, 31.v.2007 (J. Hanula, S. Horn & M. Ulyshen) ; ARIZONA: 1♀ Tinajas Atlas Mtns. , N32.1858 W114.0258, 28.viii.2006 (S & Hym Inst) ; ARKANSAS: 1♀ Sebastian Co., Fort Chaffee park area, nr. Wells Lake / Roberts rd. , 7.viii.2004 (Arduser) ; COLORADO: 1♀ Larimer Co., N40.6833 W105.3975, 11–12.v.2004 (S.W. Droege) ; ILLINOIS: 1♀ Carlinville , N39.2463 W089.9185, 24.vi.2006 (J. Gibbs) ; 5♀♀ Carlinville , N39.2787 W089.8898, 24.vi.2006 (J. Gibbs) ; 1♀ Carlinville , N39.3018 W089.7886, 26.vi.2006 (J. Gibbs) ; 2♀♀ E of Carlinville , N39.2673 W089.623, 25.vi.2006 (J. Gibbs) ; 1♀ Litchfield , N39.1484 W089.66696, 25.vi.2006 (J. Gibbs) ; KENTUCKY: 3♀♀ Wayne Co., N36.9292 W084.8827, 26.vii.2007 (S.W. Droege) ; MASSACHUSETTS: 1♂ Berkshire Co., Greylock Glen , 1.3 mi NW of Adams, 19.vii.2006 (M.F. Veit) ; MICHIGAN: 1♀ Allegan Co., N42.5538 W086.0437, 28.viii.2003 (S.W. Droege); [ PCYU] ; MISSISSIPPI: 1♀ Warren Co., 13 mi NE Vieksburg , 26.vi.1963 (A. R. Moldenke & J.A. Woods) ; NEW YORK: 1♀ Otsego Co., Oneonta, Soccer Hall of Fame , 5.vii.2002 (J.S. Ascher); [ AMNH] ; NORTH CAROLINA: 1♀ N35.13941 W080.1394, 10.viii.2006 (C. Sheffield) ; 1♀ Apex , N35.89375 W078.958, 12.viii.2006 (J. Gibbs); [ PCYU] ; 1♀ Great Smoky Mtn., N.P., Cataloochee , N35.62813 W083.09997, 6.viii.2006 (J. Gibbs); [ GSNP] ; 2♀♀ Hwy 24/27 E of Charlotte, N35.24474 W080.53715, 10.viii.2006 (C. Sheffield) ; 1♀ Richmond Co., N34.8628 W079.83642, 19.v.2006 (S.W. Droege) ; 2♀♀ S. of Bryson City , Bryson City & Queen Branch Rds., N35.28377 W083.4872, 8.viii.2006 (J. Gibbs) ; PENNSYLVANIA: 3♀♀ Motel 6 off Hwy 83, N of Hwy 76, S of Harrisburg , N40.2134 W076.7155, 10.vi.2006 (J. Gibbs) ; SOUTH CAROLINA: 1♀ C. Sandhills NWR , N34.547 W080.1766, 6–7.ix.2006 (S.W. Droege); 1♀ Chesterfield Co., N34.51857 W080.2212, 18.v.2006 (S.W. Droege) ; 1♀ Hwy 28, S of Anderson, N35.58276 W083.83714, 9.viii.2006 (J. Gibbs) ; 1♀ Okanee Co., nr Walhalla , N34.80472 W083.14587, 9.viii.2006 (J. Gibbs); [ PCYU] ; SOUTH DAKOTA: 1♀ Volga; [ ANSP] ; TENNESSEE: 2♀♀ Gatlinburg, Hwy 321, N35.75988 W083.3615, 8.viii.2006 (J. Gibbs); [ PCYU] ; 1♀ Great Smoky Mtn. N.P., Cades Cove, Mill Creek , N35.58276 W083.8371, 5.viii.2006 (J. Gibbs); [ GSNP] ; TEXAS: 1♀ Bastrop Co., Camp Swift ( Post Oak ), N30.285 W097.287, 20.v.2004 (J.L. Neff) ; 1♀ Travis Co., Austin , 15.ii.1990 (J. Neff); [ CTMI] ; VIRGINIA: 1♀ Fluvanna Co., N37.7529 W078.4573, 14.vii.2003 (S.W. Droege) ; 1♂ Mt. Rogers , Jefferson N.F., N36.88837 W081.13826, 14.viii.2006 (J. Gibbs) ; WEST VIRGINIA: 1♀ Hampshire Co., N39.34575 W078.4026, 29–30.v.2004 (S.W. Droege); [ PCYU] .

Floral records. ACANTHACEAE : Justicia americana , ALISMATACEAE : Alisma plantago-aquatica , Sagittaria latifolia , ANACARDIACEAE : Rhus aromatica , R. copallinum , R. glabra , APIACEAE : Chaerophyllum procumbens , Cicuta maculata , Cryptotaenia canadensis , Daucus carota , Erigenia bulbosa , Eryngium yuccifolium , Heracleum maximum , Osmorhiza longistylis , Oxypolis rigidior , Pastinaca sativa , Perideridia americana , Polytaenia nuttallii , Sanicula marilandica , Sium suave , Taenidia integerrima , Thaspium trifoliatum trifoliatum , Zizia aurea , APOCYNACEAE : Apocynum androsaemifolium , AQUIFOLI- ACEAE: Ilex , ASCLEPIADACEAE : Asclepias sullivantii , A. verticillata , Cynanchum laeve , ASTERACEAE : Achillea millefolium , Ageratina altissima , Antennaria neglecta , A. plantaginifolia , Anthemis cotula , Arctium lappa , A. minus , Arnoglossum atriplicifolium , A. reniforme , Baccharis emoryi , “ Bigelovia wrightii ”, Boltonia asteroides , Cirsium altissimum , C. arvense , C. discolor , Conoclinium coelestinum , Conyza canadensis , Echinacea purpurea , Erigeron annuus , E. philadelphicus , E. strigosus , Eupatorium altissimum , E. serotinum , Eurybia furcata , E. macrophylla , Euthamia graminifolia , E. caroliniana , E. occidentalis , Gnaphalium polycephalum , Grindelia squarrosa , Helenium , Helianthus annuus , H. tuberosus , Heliopsis helianthoides , Hieracium , Lactuca floridana , Leucanthemum vulgare , Pityopsis graminifolia tenuifolia , Pyrrhopappus carolinianus , Ratibida , Rudbeckia hirta , R. subtomentosa , R. triloba , Silphium laciniatum , S. perfoliatum , Solidago missouriensis , S. ulmifolia , Symphyotrichum lanceolatum lanceolatum , Symphyotrichum pilosum pilosum , Taraxacum , Verbesina helianthoides , BALSAMINACEAE : Impatiens , BERBERI- DACEAE: Caulophyllum thalictroides , BIGNONIACEAE : Campsis radicans , BORAGINACEAE : Hackelia virginiana , BRASSICACEAE : Arabis shortii , Barbarea , Berteroa , Brassica , Capsella bursa-pastoris , Cardamine concatenata , Lepidium virginicum , Sisymbrium “ canescens ”, CAMPANULACEAE : Campanulastrum americanum , Lobelia inflata , CAPPARACEAE : Cleome , CAPRIFOLIACEAE : Sambucus nigra canadensis , Symphoricarpos orbiculatus , S. albus , Viburnum prunifolium , CARYOPHYLLACEAE : Cerastium nutans , Gypsophila , Stellaria longifolia , S. media , CELASTRACEAE : Euonymus atropurpureus , COR- NACEAE: Cornus florida , C. racemosa , CYRILLACEAE : Cyrilla racemiflora , EBENACEAE : Diospyros virginiana , EUPHORBIACEAE : Euphorbia corollata , ERICACEAE : Vaccinium arboreum , FABACEAE : Amorpha canescens , A. fruticosa , Baptisia , Cercis canadensis , Chamaecrista fasciculata , Dalea candida , Gleditsia triacanthos , Lotus , Melilotus indicus , M. officinalis , Robinia , Senna marilandica , Strophostyles leiosperma , Trifolium , GERANIACEAE : Geranium carolinianum , GROSSULARIACEAE : Ribes cynosbati , R. uva-crispa sativum , R. nigrum , HYDRANGEACEAE : Hydrangea arborescens , Philadelphus inodorus , HYDROPHYLLACEAE : Ellisia nyctelea , LAMIACEAE : Agastache nepetoides , Blephilia ciliata , B. hirsuta , Leonurus cardiaca , Lycopus americanus , Monarda , Nepeta cataria , Pycnanthemum flexuosum , P. virginianum , Salvia , Scutellaria siphocampyloides , Trichostema brachiatum , LAURACEAE : Sassafras albidum , LILIACEAE : Allium cernuum , Hypoxis hirsuta , Maianthemum racemosa , M. stellatum , Narcissus , Stenanthium angustifolium , LINACEAE : Linum lewisii , LYTHRACEAE : Ammania coccinea , MALVA- CEAE: Althaea rosea , Malva rotundifolia , MOLLUGINACEAE : Mollugo verticillata , NELUMBO- NACEAE: Nelumbo lutea , ONAGRACEAE : Circaea lutetiana , Ludwigia alternifolia , PAPAVERACEAE : Sanguinaria canadensis , PHYTOLACCACEAE : Phytolacca americana , PLANTAGINACEAE : Plantago , POACEAE : Panicum , Poa pratensis , POLYGONACEAE : Fagopyrum , Polygonum pensylvanicum , P. persicaria , P. scandens , PORTULACACEAE : Claytonia virginica , RANUNCULACEAE : Clematis virginiana , Enemion biternatum , Hepatica nobilis acuta , Ranunculus abortivus , R. fascicularis , R. hispidus nitidus , Thalictrum thalictroides , RHAMNACEAE : Ceanothus americanus , Rhamnus lanceolata , ROSACEAE : Amelanchier canadensis , Aruncus dioicus , Crataegus aff. chrysocarpa chrysocarpa , C. crus-galli , C. mollis , Cydonia oblonga , Fragaria , Geum canadense , G. vernum , Gillenia stipulata , Malus pumila , Photinia , Potentilla norvegica , P. recta , Prunus americana , P. avium , P. persica , P. serotina , P. salicina, Pyrancantha , Pyrus communis , Rubus flagellaris , RUBIACEAE : Cephalanthus , Houstonia purpurea , RUTACEAE : Ptelea trifoliata , Zanthoxylum americanum , SALICACEAE : Salix amygdaloides , S. cordata , S. humilis , S. interior , S. nigra , SAXIFRAGACEAE : Heuchera americana hispida , Mitella diphylla , Saxifraga pensylvanica , SCRO- PHULARIACEAE: Lindernia dubia , Scrophularia marilandica , Veronica peregrina , Veronicastrum virginicum , SMILACACEAE : Smilax herbacea , SOLANACEAE : Solanum rostratum , TILIACEAE : Tilia americana , VIOLACEAE : Viola pubescens , VITACEAE : Vitis, UNCLEAR PLACEMENT : “ Gerardia ”.

Biology. Reinhard 1924: (predator, as H. sparsus ); Bohart 1941: (stylopization, as H. sparsus ); Evans & Lin 1959: (predators, listed as inconspicuus and stultus ); Michener & Wille 1961: (bionomics, as inconspicuus ); Evans 1964: (predator); Knerer & Atwood 1967: (parasite); Michener 1974, pp. 7, 44, 45, 61, 72, 77, 80, 81, 83, 85, 86, 95, 119, 122, 139, 140, 142, 144, 152, 182, 197, 210, 212, 222, 240, 244, 250, 274, 275, 277, 283, 286: (nest sites, nest architecture, natural history, polygynous spring phase, cell recognition, sex ratios, caste differences, mandibular wear, longevity, seasonal size variation, caste differentiation, laying workers, ontogenetic division of labour, foraging, nest activity, nest recognition, defense, sociality); Evans, 1975: (predator); Michener 1978: (parasite information); Jones et al. 1980: (stylopization); Wcislo 1997: (social parasite); Danforth 1999: (phylogeny), Danforth & Ji 2001: (phylogeny); Danforth et al. 2003: (phylogeny); MacGowan 2006: (mutillid parasite).

Comments. Common, variable in size and shape due to caste-based allometry.

Figures

FIGURE 124. Distribution of Lasioglossum imbrex (dark grey) and L. imitatum (light grey).

FIGURE 125. Lasioglossum imitatum (Smith). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) T3–T5. Scale bars, A–C = 1 mm.