Lasioglossum (Dialictus) pilosum (Smith)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 253-258

Lasioglossum (Dialictus) pilosum (Smith)

( Figures 180A–C , 181A–E )

Halictus pilosus Smith, 1853: 71 . ♀.

Holotype. ♀ North America [ BMNH: B.M. Type 17a 1000]. Examined.

Halictus floridanus caesareus Cockerell, 1916: 11 . ♀.

Holotype. ♀ USA, New Jersey, Ocean Grove , 12.vi.1893 [ NMNH: 27761]. Examined.

Dialictus otsegoensis Mitchell, 1960: 440 . ♂. [new synonymy]

Holotype. ♂ USA, Michigan, Ostego Co., 7–24.vii.1955 ( R. R. Dreisbach); [ NCSU]. Examined.

Taxonomy. Robertson, 1895: Halictus pilosus ♂, p. 117 (description); Robertson, 1902: Chloralictus pilosus , p. 248 (key); Cockerell, 1905: Halictus pilosus ♀, p. 351 (redescription); Viereck, 1916: Halictus (Chloralictus) pilosus , p. 706 (key); Michener, 1951: Lasioglossum (Chloralictus) floridanum caesareum , p. 1113, L. (C.) pilosum , p. 1116 (catalogue); Mitchell, 1960: Dialictus pilosus pilosus ♂, p. 413 (redescription); Mitchell, 1962: Dialictus pilosus pilous , p. 547 (synonymy); Krombein, 1967: Lasioglossum (Dialictus) otsegoense , p. 465, L. (D.) pilosum pilosum , p. 465 (catalogue); Dialictus otsegoensis , p. 1969, D. pilosus pilosus , p. 1970 (catalogue); Moure & Hurd, 1987: Dialictus otsegoensis , p. 118, D. pilosus pilosus , p. 123 (catalogue).

Diagnosis. Females of L. pilosum , L. leucocomum and L. succinipenne can be recognised by the combination of an elongate head (length/width ratio = 1.03–1.09), dense mesoscutal punctation (i<d), rugulose mesepisternum, subhyaline wing, brownish yellow pterostigma, rugoso-striate metapostnotum finely rugosostriate, metallic metasomal terga, T1 acarinarial fan strong, T1 dorsolaterally, T2 basolaterall and T3–T5 entirely with abundant tomentum. Female L. pilosum may be further distinguished by the predominately yellowish hairs, conspicuously dense mesoscutal setae and subparallel apicolateral margins of the clypeus ( Fig. 180C ). Female L. leucocomum have dull white to yellowish hair, less dense mesoscutal setae and distinctly convergent apicolateral margins of the clypeus ( Fig. 134C ). Female L. succinipenne have dull white hairs, less dense mesoscutal setae and subparallel apicolateral margins of the clypeus. The Eastern USA species L. floridanum is most similar to L. pilosum but has virtually no rugae on the metapostnotum distinct from the surrounding microsculpture and usually less abundant pubescence.

Males of L. pilosum and L. succinipenne can be recognised by the yellow apical margin of the clypeus, dense mesoscutal punctation and deep punctures across the metasomal terga. Male L. pilosum lack distinct punctures on the mesepisternum ( Fig. 58A ) which are present in male L. succinipenne ( Fig. 58B ). Male L. floridanum usually lack the yellow clypeal band and have weak metapostnotal rugae. The male of L. leucocomum is currently unknown.

Redescription. FEMALE. Length 4.91–6.35 mm; head length 1.61–1.80 mm; head width 1.54–1.75 mm; forewing length 3.72–4.27 mm.

Colouration. Head and mesosoma pale green to golden green. Clypeus with apical half blackish brown. Supraclypeal area bronze. Antenna dark brown, flagellum with ventral surface reddish brown at apex. Tegula amber. Wing membrane subhyaline, venation and pterostigma pale amber. Legs brown, protibial base and medio- and distitarsi reddish brown. Metasomal terga golden green, sterna brown, apical margins pale, translucent yellow.

Pubescence. Dull white to yellowish. Dense. Head and mesosoma with moderately dense woolly hairs (1– 1.5 OD), longest on genal beard, metanotum and mesopleuron (2–2.5 OD). Paraocular area and gena with subappressed tomentum sometimes partially obscuring surface. Mesoscutum with dense setae. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with dense, fine setae. T1 acarinarial fan complete and dense. T1 apicolateral portion with dense tomentum. T2 basal and lateral portions, and T3–T5 with dense tomentum obscuring surface. T2–T4 apical margins with moderately dense fringes.

Surface sculpture. Face imbricate, punctation fine. Clypeus polished, imbricate, punctation (i=1–3d). Supraclypeal area with punctation moderately dense (i=1–1.5d). Lower paraocular and antennocular areas with punctation dense (i≤d). Upper paraocular area and frons punctate-reticulate. Ocellocular area minutely punctate (i≤d). Gena and postgena lineolate. Mesoscutum weakly imbricate, punctation dense on medial portion of disc (i<d), punctate-reticulate mesad and laterad of parapsidal lines and on anterolateral portions. Mesoscutellum polished, submedial punctation moderately sparse (i=1–2d). Axilla punctate. Metanotum ruguloso-imbricate. Preëpisternum rugulose. Hypoepimeral area rugulose. Mesepisternum weakly rugulose. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum weakly, incompletely rugoso-striate, posterior margin imbricate. Propodeum with dorsolateral slope and lateral and posterior surfaces imbricate. Metasomal terga weakly coriarious, punctation moderately dense throughout (i=1–1.5d).

Structure. Head elongate (length/width ratio = 1.03–1.08). Eyes convergent below (UOD/LOD ratio = 1.18–1.22). 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 narrower than eye. Inner metatibial spur pectinate with 4 teeth. Metapostnotum truncate (MMR ratio = 1.27–1.38), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina fine, lateral carina weak, not reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 5.12– 5.73 mm; head length 1.58–1.99 mm; head width 1.37–1.68 mm; forewing length 3.48–4.33 mm.

Colouration. Labrum brownish yellow. Mandible brownish yellow. Clypeus distal margin yellowish brown, rarely brown. Flagellum with ventral surface ferruginous. Legs brown, tibial bases and apices and tarsi brownish yellow.

Pubescence. Moderately dense. Face below eye emargination with tomentum obscuring paraocular area, partially obscuring clypeus and supraclypeal area. T1 acarinarial area with sparse fan of appressed hairs. T2– T3 basolaterally and T4 basally with sparse tomentum. S2–S3 entirely and S4 laterally with posteriorly directed hair patches (1–1.5 OD).

Surface sculpture. Clypeal punctation moderately dense (i=1–2d). Propodeum with dorsolateral slope and lateral and posterior surfaces rugulose. Metasomal terga punctation deep, distinct.

Structure. Head very elongate (length/width ratio = 1.13–1.17). Eyes convergent below (UOD/LOD ratio = 1.35–1.64). Clypeus 2/3 below suborbital tangent, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD = 1.0). Frontal line carinate, ending 2 OD below median ocellus. Pedicel shorter than F1. F2 length 1.6–1.8X F1. F2–F10 moderately elongate (length/width ratio = 1.55–1.64). Metapostnotum truncate (MMR ratio = 1.21–1.35), posterior margin weakly angled onto posterior surface.

Terminalia . S7 with median lobe clavate, apex rounded ( Fig. 181D ). S8 with apicomedial margin weakly convex ( Fig. 181D ). Genitalia as in Fig. 181D–E . Gonobase with ventral arms widely separated. Gonostylus small, dorsal setae elongate. Retrorse lobe elongate, strongly attenuated apically.

Range. Ontario west to Wisconsin, south to North Carolina ( Fig. 182 ).

Additional material examined. CANADA: ONTARIO: 1♀ Haldimane-Norfolk Reg., Delhi-Simcoe Railway , 14.vii.2001 (S. Paiero); [ DEBU] ; 1♂ Norfolk Co., Pterophylla Plant Nursery , N42°38.404´W080°34.379´, 13.viii–22.viii.2006 (P.J. Carson) ; 1♀ Queen’s University Biological Stn. , 17.vii.2006 (L. Packer) ; QUEBEC: 2♀ W of Normandin , N48°48´16.8´´ W72°36´22.5´´, 172 m, 8.vi.2009 (M. Chagnon) ;

[ PCYU]; USA: INDIANA: 3♀ Jackson Co., N38.8799 W086.056, 26.vii.2003 ; MARYLAND: 1♀ Patuxent Wildlife …, N39 W076.7, 26–27.v.2002 (H.W. Ikerd) ; 1♂ Pr. George’s Co., N38.9581 W076.7444, 20.viii.2004 (S. Kolski); [ PCYU] ; MICHIGAN: 12♀ Huron Co., N43.80147 W82.89227, 30.vii.2009 (Tuell et al.); [ ARC] ; NEW YORK: 1♀ Suffolk Co., 6.ix.2005 (S.W. Droege); [ PCYU] ; 1♀ Wayne Co., Endress , Sodus Pt., 19.v.2009 (M.G. Park); [ CUIC] ; NORTH CAROLINA: 1♂ Great Smoky Mountain N.P., Cades Cove, Hyatt Rd. at Abhram’s Creek , N35.59232 W083.8236, 5.viii.2006 (J. Gibbs) ; 1♀ Great Smoky Mountain N.P., Cataloochee overlook, N35.6399 W083.06017, 6.viii.2006 (C. Sheffield); [ GSNP] ; 1♀ Junaluska Meadow , N35.54289 W082.9566, 7.viii.2006 (J. Gibbs) ; 2♀ N of Doughton Park , N36.44752 W081.02898, 14.viii.2006 (J. Gibbs) ; TENNESSEE: 1♀ Hwy 321, nr. Gatlinburg , N35.75988 W083.3615, 8.viii.2006 (J. Gibbs) ; VIRGINIA: 1♀ Assateague I., N37.9804 W075.2926, 30.vi–1.vii.2006 (S.W. Droege) ; 1♀ Assateague I., N37.891 W075.3458, 1–2.vii.2006 (S.W. Droege) ; 1♀ Hwy 21, 8 km S of Elk, N36.68854 W081.17776, 14.viii.2006 (J. Gibbs) ; WEST VIRGINIA: 1♀ Hampshire Co., N39.3348 W078.458, 20.ix (S.W. Droege) ; WISCONSIN: 1♀ Sauk Co., Spring Green Preserve , N43.19785 W090.05904, 23.vii.2006 (A. Wolf); [ PCYU] .

Floral records. ACANTHACEAE : Justicia americana , ALISMATACEAE : Sagittaria latifolia , ANAC- ARDIACEAE: Rhus copallinum , R. glabra , APIACEAE : Apium , Cryptotaenia canadensis , Erigenia bulbosa , Eryngium yuccifolium , Heracleum maximum , Osmorhiza longistylis , Polytaenia nuttallii , Zizia aurea , APOC- YNACEAE: Apocynum androsaemifolium , ASCLEPIADACEAE : Asclepias sullivantii , A. verticillata , ASTERACEAE : Achillea millefolium , Anthemis cotula , Antennaria plantaginifolia , Arnoglossum reniforme , Cirsium altissimum , C. vulgare , Conyza canadensis , Coreopsis palmata , C. tripteris , Echinacea pallida , E. purpurea , Erigeron philadelphicus , Eupatorium perfoliatum , Haplopappus , Helenium , Helianthus annuus , H. divaricatus , H. laetiflorus , H. mollis , H. tuberosus , Heliopsis helianthoides , Hieracium , Hypochaeris , Krigia biflora , Lactuca floridana , Leucanthemum vulgare , Parthenium integrifolium , Pseudognaphalium obtusifolium , Pyrrhopappus carolinianus , Rudbeckia hirta , R. laciniata , R. subtomentosa , R. triloba , Silphium laciniatum , S. perfoliatum , Solidago , Symphyotrichum anomalum , S. drummondii , S. pilosum , S. ericoides , S. puniceum , Taraxacum officinale , Verbesina helianthoides , Vernonia fasciculata , BRASSICACEAE : Barbarea , Brassica , Cardamine bulbosa , C. concatenata , Descurainia pinnata , Lepidium virginicum , Nasturtium , Raphanus sativus , Rorippa teres , CACTACEAE : Opuntia , CAMPANULACEAE : Lobelia spicata leptostachys , CAPRIFOLIACEAE : Weigela japonica , Viburnum prunifolium , CARYOPHYLLACEAE : Cerastium , Stellaria , CLUSIACEAE : Hypericum punctatum , CORNACEAE : Cornus amomum , C. florida , C. racemosa , CUCURBITACEAE : Cucurbita , EBENACEAE : Diospyros , ERICACEAE : Vaccinium , EUPHORBIACEAE : Euphorbia corollata , FABACEAE : Amorpha canescens , Cercis anadensis , Chamaecrista fasciculata , Dalea purpurea , Lupinus , Medicago , Melilotus officinalis , Tephrosia , Trifolium repens , GERANIACEAE : Geranium maculatum , GROSSULARIACEAE : Ribes uva-crispa sativum , HYDROPHYLLACEAE : Hydrophyllum appendiculatum , IRIDACEAE : Sisyrinchium angustifolium , LAMIACEAE : Blephilia ciliata , B. hirsuta , Monarda fistulosa , Nepeta cataria , Pycnanthemum flexuosum , P. verticillatum pilosum , Trichostema brachiatum , LILIACEAE : Allium tricoccum , Camassia scilloides , Erythronium albidum , Uvularia grandiflora , LYTHRACEAE : Ammannia coccinea , MALVACEAE : Alcea rosea , Malva pusilla , MOLLUGINACEAE : Mollugo verticillata , NELUMBONACEAE : Nelumbo lutea , ONAGRACEAE : Ludwigia alternifolia , Oenothera , OXALIDACEAE : Oxalis corniculata , O. violacea , POLEMONIACEAE : Polemonium reptans , POLYGONACEAE : Polygonum lapathifolium , PORTULACACEAE : Claytonia virginica , RANUNCU- LACEAE: Enemion biternatum , Pulsatilla patens multifida , Ranunculus abortivus , R. fascicularis , R. hispidus , RHAMNACEAE : Ceanothus , Rhamnus lanceolata , ROSACEAE : Amelanchier canadensis , Crataegus crus-galli , C. mollis , Fragaria virginiana grayana , Geum canadense , Malus pumila , Photinia , Potentilla norvegica monspeliensis , Prunus americana , P. avium , P. serotina , Pyracantha , Pyrus , Rubus , RUBIACEAE : Houstonia purpurea calycosa , RUTACEAE : Ptelea trifoliata , SALICACEAE : Salix amygdaloides , S. cordata , S. discolor , S. drummondiana , S. humilis , S. interior , S. nigra , SAXIFRAGACEAE : Mitella diphylla , SCROPHULARIACEAE : Lindernia dubia , Penstemon laevigatus , Veronica peregina , Veronicastrum virginicum , VERBENACEAE : Phyla lanceolata , Verbena urticifolia , VIOLACEAE : Viola pubescens , ACAN- THACEAE/ SCROPHULARIACEAE : “ Gerardia ”.

Biology. Reinhard 1924: (predator); Evans & Lin, 1959: (predators); Knerer & Atwood, 1962: (floral records, nesting site); Evans, 1975: (predator); Michener, 1978: (parasite); Danforth 1999: (phylogeny); Danforth & Ji 2001: (phylogeny); Danforth et al. 2003: (phylogeny).

Comments. Common.

Mitchell (1960) recognised two subspecies, a northern form L. pilosum pilosum and a southern form L. pilosum floridanum . The diagnostic anatomical characters for both subspecies are at least partially sympatric ( Fig. 182 ) and can be predicted with 96.8 % success using DNA barcode data. The presence of morphologically recognisable and genetically distinct forms in sympatry would suggest specific rather than subspecific status. The two subspecies are herein recognised as separate species L. pilosum and L. floridanum (= D. intrepidus Mitchell [new synonymy]) following Michener (1951). A northeastern subspecies described by Lovell (1908) is also recognised as a separate species (see L. leucocomum above). Specimens identified as L. pilosum from west of the Mississippi are likely to be the related species L. succinipenne (see below).

Figures

FIGURE 58. Mesepisternum of male (A) L. pilosum, rugulose, (B) L. succinipenne, reticulate-punctate.

FIGURE 134. Lasioglossum leucocomum (Sandhouse). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 180. Lasioglossum pilosum (Smith). Female (A) lateral habitus; (B) dorsal habitus; (C) face. Scale bars, A–C = 1 mm.

FIGURE 181. Lasioglossum pilosum (Smith). 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 182. Distribution of Lasioglossum pilosum (medium grey), L. floridanum (dark grey), and L. planatum (light grey).