Lasioglossum (Dialictus) illinoense (Robertson)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 149-153

publication ID 10.11646/zootaxa.2591.1.1

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Lasioglossum (Dialictus) illinoense (Robertson)


Lasioglossum (Dialictus) illinoense (Robertson)

( Figures 121A–E, 122A–E)

Halictus illinoensis Robertson, 1892: 271 . ♀.

Lectotype. ♀ USA, Illinois, Carlinville , 12.viii., (C. Robertson); [ INHS: 179,611] by W.E. LaBerge. Examined. Halictus illinoisensis Smith, 1910: 688 (Emend.)

Taxonomy. Robertson, 1902: Chloralictus Illinoensis , p. 249 (key); Michener, 1951: Lasioglossum (Chloralictus) illinoense , p. 1114 (catalogue); Mitchell, 1960: Dialictus illinoensis ♂, p. 399 (redescription); Krombein, 1967: Lasioglossum (Dialictus) illinoense , p. 464 (catalogue); Hurd, 1979: Dialictus illinoensis , p. 1966 (catalogue); Moure & Hurd, 1987: Dialictus illinoensis , p. 105 (catalogue).

Diagnosis. Females of L. illinoense can be distinguished from all other Canadian Dialictus by the conically produced protrochanter ( Fig. 121D). They are further recognisable by the combination of a wide head (length/width ratio = 0.90–0.92), very strong carina delimiting lower margin of dorsolateral slope ( Fig. 121E), fine mesoscutal punctures that are sparse on central disc but dense laterad of parapsidal line, and wide distal margin of clypeus.

Males of L. illinoense can be recognised by diagnostic combination of a yellow maculation on the distal margin of the clypeus, wide head (length/width ratio = 0.94–0.95), mesoscutum with posterior half polished due to lack of microsculpture and with fine punctures, widely spaced on the central disc (i=1–3d), rugulose mesepisternum, apical halves of metasomal terga impunctate except along premarginal line, and metasomal sterna with relatively sparse plumose hairs.

Redescription. FEMALE. Length 4.03–5.37 mm; head length 1.06–1.34 mm; head width 1.18–1.46 mm; forewing length 3.11–3.72 mm.

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

Pubescence. Dull white. 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 with scattered tomentum partially obscuring surface. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with very sparse, fine setae. T1 acarinarial fan of appressed hairs small with wide dorsal opening. T2 basolaterally and T3–T5 entirely with sparse, scattered tomentum. T2 apicolateral and T3–T4 apical margins with very sparse fringes.

Surface sculpture. Face polished, weakly imbricate, punctation fine. Clypeus polished, punctation moderately sparse (i=1–3d). Supraclypeal area with punctation moderately sparse (i=1–3d). Lower paraocular and antennocular areas with punctation dense (i≤d). Upper paraocular area and frons punctation clearly separated (i=d). Ocellocular area punctate (i=d). Gena polished. Postgena imbricate. Mesoscutum polished, faintly imbricate, punctation fine, moderately sparse over majority of disc (i=1–3d), dense laterad of parapsidal line and on anterolateral portions (i≤d). Mesoscutellum similar to mesoscutum polished, punctation fine. Axilla punctate. Metanotum imbricate. Preëpisternum and mesepisternum rugose, rugulose below. Metepisternum with dorsal half rugoso-striate, ventral half imbricate. Metapostnotum coarsely rugoso-striate. Propodeum with dorsolateral slope imbricate, lateral and posterior surfaces imbricate. Metasomal terga integument polished, apical impressed areas faintly coriarious, punctation on basal halves sparse (i=1.5–3d), apical half impunctate (except along premarginal line).

Structure. Head very wide (length/width ratio = 0.90–0.92). Eyes weakly convergent below (UOD/LOD ratio = 1.24–1.26). Clypeus 1/3 below suborbital tangent, apicolateral margins parallel, distal margin wide, apicolateral angle rounded. Antennal sockets close (IAD/OAD = 0.6). Frontal line carinate, ending fine, 2.5 OD below median ocellus. Gena narrower than eye. Procoxa with conical tubercle. Inner metatibial spur pectinate with 3–4 teeth. Metapostnotum moderately elongate (MMR ratio = 1.08–1.33), posterior margin weakly angled onto posterior surface. Propodeum with dorsolateral slope delimited below by strong oblique carinae forming obtuse angle, lateral carina reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.15– 4.51 mm; head length 1.13–1.30 mm head width 1.19–1.38 mm forewing length 3.23–3.42 mm.

Colouration. Labrum, mandible apex, and Clypeus with apical half yellow. Flagellum with ventral surface bright yellow. Tibial bases and apices, tarsi and pro- and mesotibia with ventral surface yellow.

Pubescence. Lower paraocular area with dense tomentum obscuring surface. Clypeus, supraclypeal area and lower frons with scattered tomentum partially obscuring surface. Sterna sparsely pubescent, S2–S4 apically with subappressed hairs.

Surface sculpture. Metapostnotum coarsely rugoso-striate, lateral surface rugulose.

Structure. Head wide (length/width ratio = 0.94–0.95). Eyes strongly convergent below (UOD/LOD ratio = 1.45–1.61). Antennal sockets distant (IAD/OAD = 2.0). Frontal line carinate, ending fine, OD below median ocellus. Pedicel subequal to F1. F2 length 2X F1. F2–F10 moderately long (length/width ratio = 1.40– 1.75). Metapostnotum moderately elongate (MMR ratio = 1.18–1.25), posterior margin sharply angled onto posterior surface.

Terminalia . S7 with median lobe strongly clavate, sides concave, apex rounded ( Fig. 122D). S8 with apicomedial margin weakly convex ( Fig. 122D). Genitalia as shown in Fig. 122D–E. Gonobase with ventral arms narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobe elongate, weakly attenuated apically.

Range. Nova Scotia, south to Georgia, Mississippi, west to Kansas ( Fig. 120).

Additional material examined. USA: GEORGIA: 1♀ Liberty Co., St. Catherines Isl. , N31°40.9´W081°08.8´, 16–21.iv.1995 (A. Sharkov) GoogleMaps ; 1♀ Liberty Co., St. Catherines Isl. , N31°40.9´W081°08.8´, 23– 28.iv.1995 (A. Sharkov) GoogleMaps ; 7♀ Liberty Co., St. Catherines Isl. , N31°41´W081°09´, 30.iv–4.v.1995 (A. Sharkov) GoogleMaps ; 8♀ Liberty Co., St. Catherines Isl., Road b/w Windmill 2 nd and Gator Pond , 22– (A. Sharkov) ; ILLINOIS: 1♀ Carlinville , N39.2787 W089.8898, (J. Gibbs) GoogleMaps ; INDIANA: 4♀ Jackson Co., N38.8799 W086.056, 26.vii.2003 (S.W. Droege) GoogleMaps ; 1♀ Jasper Co., Nipsco , bpt, 22.v.2003 ( R. P. Jean) ; KANSAS: 1♀ Douglas Co., N38˚49.168ʹ W95˚21.788ʹ, 9.viii.2004 (J. Hopwood) ; KENTUCKY: 13♀ Wayne Co., N36.924 W084.8715, 23–24.vii.2007 (S.W. Droege) GoogleMaps ; MARYLAND: 1♀ Pr. George’s Co., N38.9764 W076.7491, 20.viii.2004 (S. Kolski) GoogleMaps ; 1♀ Pr. George’s Co., N38.9591 W076.734, 20.viii.2004 (S. Kolski) GoogleMaps ; 1♂, Pr. George’s Co., N38.9627 W076.7477, 21.ix.2006 (K. Hutson) GoogleMaps ; 1♂, Pr. George’s Co., N38.9632 W076.7479, 21.ix.2006 (K. Hutson) GoogleMaps ; MICHIGAN: 1♀ Alleghan Co., N42.5538 W86.0437, 28.viii.2003 (S.W. Droege) GoogleMaps ; NORTH CAROLINA: 3♀ Apex , N35.89375 W078.958, 12.viii.2006 (J. Gibbs) GoogleMaps ; 1♀ Junaluska Meadow , N35.54289 W082.95664, 7.viii.2006 (Gibbs & Sheffield) GoogleMaps ; 1♀ S. of Bryson City , Bryson City & Queen Branch Rds., N35.28377 W083.4872, 8.viii.2006 (J. Gibbs) GoogleMaps ; PENNSYLVANIA: 1♀ Motel 6 off Hwy 83, N of Hwy 76, S of Harrisburg , N40.2134 W076.7155, (J. Gibbs) GoogleMaps ; SOUTH CAROLINA: 1♂ C. Sandhills NWR, N34.5597 W080.2561, 6.ix.2006 (S.W. Droege) GoogleMaps ; 1♀ Chesterfield Co.,

N34.5789 W080.2334, 18.v.2006 (S.W. Droege); 1♀ Okanee Co., Walhalla GoogleMaps , N34.80472 W083.14587, 8.viii.2006 (J. Gibbs); TENNESSEE: 2♀ Gatlinburg, Hwy 321 GoogleMaps , N35.75988 W083.3615, 8.viii.2006 (J. Gibbs); [ PCYU]; TEXAS: 1♀ Kerr Co., Mary Meade Ranch GoogleMaps , N29.992 W099.388, 17.viii–28.ix.2006 (J.C. Abbott); [ CTMI]; WEST VIRGINIA: 4♀ Hampshire Co .. GoogleMaps , N39.3012 W078.4358, 11.vii.2002 (S.W. Droege); [ PCYU]; WISCONSIN: 2♀ Dane Co., Henderson Savanna, 20.viii.1995; [ IRCW] GoogleMaps .

Floral records. ANACARDIACEAE : Rhus , APIACEAE : Cryptotaenia canadensis , Daucus carota , Sium suave , APOCYNACEAE : Apocynum androsaemifolium , MALVACEAE : Althaea rosea , Malva rotundifolia ”, AQUIFOLIACEAE : Ilex , ASCLEPIADACEAE : Asclepias , Cynanchum laeve , ASTERACEAE : Antennaria , Erigeron , Eupatorium altissimum , Helianthus divaricatus , Pyrrhopappus carolinianus , Solidago missouriensis , S. nemoralis , Symphyotrichum ericoides , S. pilosum , Taraxacum officinale , CAPPARACEAE : Cleome serrulata , FABACEAE : Baptisia , Gleditsia triacanthos , Glycine max , Medicago , Vicia , LAMI- ACEAE: Pycnanthemum , Salvia , LAURACEAE : Sassafras variifolium , PAPAVERACEAE : Argemone pinnatifida ”, PLANTAGINACEAE : Plantago , PORTULACACEAE : Claytonia virginica , RANUNCULACEAE : Clematis virginiana , RHAMNACEAE : Ceanothus , Rhamnus lanceolata , ROSA- CEAE: Photinia , Prunus , Pyrus , SALICACEAE : Salix amygdaloides , S. cordata , TILIACEAE : Tilia americana, UNKNOWN : “ Waldateria”.

Biology. Reinhard 1924: (predator).

Comments. Rare in Canada. Lasioglossum illinoense is recorded from Nova Scotia by Mitchell (1960) but no Canadian specimens have been examined. Common in some Eastern USA including states adjacent to Ontario. Formerly H. (C.) politissimus Cockerell has been recorded as a synonym of this species ( Mitchell 1960). From examination of the holotype this is clearly incorrect. The name H. politissimus is a junior synonym of L. connexum (Cresson) [new synonymy].


Illinois Natural History Survey


Departamento de Geologia, Universidad de Chile


The Packer Collection at York University


Madison, University of Wisconsin














Lasioglossum (Dialictus) illinoense (Robertson)

Gibbs, Jason 2010

Halictus illinoensis

Robertson, C. 1892: 271