Lasioglossum (Dialictus) trigeminum Gibbs

Gibbs, Jason, 2011, Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini), Zootaxa 3073, pp. 1-216 : 201-205

publication ID 10.5281/zenodo.1049595

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Lasioglossum (Dialictus) trigeminum Gibbs

new species

Lasioglossum (Dialictus) trigeminum Gibbs , new species

( Figures 218–222 View FIGURE 218 View FIGURE 219 View FIGURE 220 View FIGURE 221 View FIGURE 222 )

Holotype. Ƥ USA, Indiana, Jackson Co., N 38.8799 W086.056, 26.vii. 2003 (S.W. Droege); [ PCYU].

Diagnosis. Female L. trigeminum can be recognised by the following diagnostic combination: head wide (length/width ratio = 0.93–0.94) ( Fig. 218 View FIGURE 218 B); paraocular area with moderately dense tomentum; protrochanter narrow; mesoscutum polished posteriorly, punctures moderately sparse between parapsidal lines (i= 1–1.5 d) ( Fig. 219 View FIGURE 219 ); mesepisternum rugulose; metapostnotal rugae nearly reaching posterior margin; T 1 declivitous surface polished, acarinarial fan with wide dorsal opening; and metasomal terga brown, apical impressed areas densely punctate.

Male L. trigeminum can be recognised by the following diagnostic combination: face with dense tomentum ( Fig. 220 View FIGURE 220 B); flagellomeres long (length/width ratio = 1.46–1.81) ( Fig. 220 View FIGURE 220 ); mesoscutum polished-weakly imbricate, punctures moderately sparse between parapsidal lines (i= 1–1.5 d) ( Fig. 221 View FIGURE 221 ); tegula and tarsi brownish yellow; metapostnotum with weakly angled onto posterior propodeal surface; metasoma terga with sparse basolateral tomentum; and T 2 apical impressed area with narrow impunctate margin. They are most similar to L. callidum and L. versatum . Male L. callidum have wide protrochanter ( Fig. 18 View FIGURE 18 B). Male L. versatum have less dense facial tomentum and denser punctures on T 2.

Description. FEMALE. Length 4.84–5.81 mm; head length 1.42–1.58 mm; head width 1.51–1.70 mm; forewing length 3.57–3.93 mm.

Colouration. Head and mesosoma pale green or blue. Clypeus with apical half blackish brown. Antenna dark brown, flagellum with ventral surface yellow-orange. Tegula amber to brownish yellow. Wing membrane subhyaline, venation and pterostigma yellowish brown. Legs brown; tarsi reddish brown. Metasoma dark brown, terga and sterna with apical margins translucent brownish yellow.

Pubescence. Dull white. Moderately dense. 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 moderately dense subappressed tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with moderately sparse, fine hairs. T 1 acarinarial fan sparse with wide dorsal opening, intermingled with erect hairs. T 2 basolaterally, T 3 and T 4 largely covered by tomentum, obscuring surface. T 2 apicolateral and T 3 –T 4 apical margins with sparse fringes.

Surface sculpture. Face imbricate. Clypeus polished, basal margin weakly imbricate, punctation moderately sparse (i= 1–2 d). Supraclypeal area with punctation moderately sparse (i= 1–2 d). Lower paraocular area punctation dense (i≤d). Antennocular area punctation moderately dense (i= 1–1.5 d). Upper paraocular area and frons punctate-reticulate. Ocellocular area densely punctate (i≤d). Gena lineolate. Postgena weakly imbricate. Mesoscutum polished, weakly imbricate in part, punctation moderately sparse on medial portion of disc (i= 1–1.5 d), dense adjacent to parapsidal lines (laterad and mesad) (i≤d) and reticulate on anterolateral portion. Mesoscutellum similar to mesoscutum, submedial punctation moderately sparse (i= 1–2.5 d). Axilla punctate. Metanotum imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate.

Mesepisternum upper portion weakly rugulose and lower portion imbricate. Metepisternum with upper half rugoso-carinulate, lower half imbricate. Metapostnotum incompletely rugoso-carinulate, posterior margin imbricate. Propodeum with dorsolateral slope imbricate. Lateral and posterior surfaces imbricate-tessellate. Metasomal terga polished, punctation fine and moderately dense throughout (i= 1–1.5 d).

Structure. Head very wide (length/width ratio = 0.93–0.94). Eyes convergent below (UOD/LOD ratio = 1.24–1.32). Clypeus 1 / 3 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. Mesoscutum between parapsidal lines flattened. Inner metatibial spur pectinate with 4–6 branches. Metapostnotum moderately truncate (MMR ratio = 1.27– 1.45), posterior margin narrowly rounded onto posterior surface. Propodeum with oblique carina weak, virtually absent, lateral carina not reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 4.90 mm; head length 1.51 mm; head width 1.46 mm; forewing length 3.45 mm.

Colouration. Labrum and mandible infused with yellowish brown. Flagellum with ventral surface brownish yellow. Legs brown, except tibiae bases and apices, and tarsi pale brownish yellow.

Pubescence. Face below eye emargination with tomentum partially obscuring surface, denser on paraocular area. T 2 –T 4 with sparse basolateral tomentum. S 3 –S 5 apicolateral portions with subappressed hairs (1–1.5 OD).

Surface sculpture. Propodeum with dorsolateral slope and posterior propodeal surface rugose. Metasomal terga with apical impressed areas punctate, but narrowly impunctate apically.

Structure. Head round (length/width ratio = 1.02). Eyes strongly convergent below (UOD/LOD ratio = 1.54). Clypeus 2 / 3 below suborbital tangent, apicolateral margins weakly convergent. Antennal sockets distant (IAD/OAD> 1.3). Frontal line carinate, ending 2 OD below median ocellus. Pedicel shorter than F 1. F 2 length 2.0X F 1. F 2 –F 10 moderately elongate (length/width ratio = 1.46–1.81). Metapostnotum moderately elongate (MMR ratio = 1.27), posterior margin narrowly rounded onto posterior surface.

Terminalia . S 7 with median lobe columnar, apex rounded ( Fig. 222 View FIGURE 222 ). S 8 with apicomedial margin weakly convex ( Fig. 222 View FIGURE 222 ). Genital capsule as in Fig. 222 View FIGURE 222 . Gonobase with ventral rim narrowly separated. Volsella roughly ovoid. Gonostylus small, dorsal setae elongate. Retrorse lobe elongate, weakly attenuated, recurved apically.

Range. Maryland south to Georgia, west to Kansas ( Fig. 223 View FIGURE 223 ). USA: DC, FL, GA, IL, IN, KS, MD, MI, NC, NJ, SC, VA, W V.

Allotype. 3. USA: GEORGIA, Chatham Co., N 32.1323 W081.1336, 22.x. 2009 (C. Haynes); [ PCYU].

Paratypes. USA: FLORIDA: 1 Ƥ Leon Co., Tall Timbers Res. Sta., 28.iii. 1986 (B. Alexander); DISTRICT OF COLUMBIA: 1 Ƥ N 76.95472 W038.905, 26.v. 2005 (S. Rudy); [ PCYU]; ILLINOIS: 1 Ƥ Carlinville, N 39.2787 W089.8898, 2006 (J. Gibbs); [ PCYU]; KANSAS: 1 Ƥ Douglas Co., Lawrence, from nest, vii. 1957 (C.D. Michener); 1 Ƥ Lawrence, 3.vii. 1952 (C.D. Michener); 2 ƤƤ Lawrence, 1952 (C.D. Michener); 1 Ƥ Lawrence, 2.viii. 1952 (C.D. Michener); [ SEMC]; MARYLAND: 1 Ƥ Anne Arundel Co., N 39.08223 W076.7883, 14– 2005 (P. Osenton); 1 Ƥ Pr. George’s Co., N 38.978 W076.7643, 8–9.ix. 2005 (Z. Riegel); [ PCYU]; MICHIGAN: 1 Ƥ Wakefield, 13.ix. 1913 (A.T. Evans); [ UCMC]; NORTH CAROLINA: 1 Ƥ E. of Charlotte, Hwy 24 / 27, N 35.22754 W080.5583, 10.viii. 2006 (J. Gibbs); 1 Ƥ S. of Bryson City, Bryson City & Queen Branch Rds., N 35.28377 W083.4872, 8.viii. 2006 (J. Gibbs); 1 Ƥ Richmond Co., N 36.8628 W079.83642, 19.v. 2006 (S.W. Droege); 1 Ƥ Richmond Co., N 36.8937 W079.81004, 19.v. 2006 (S.W. Droege); [ PCYU]; SOUTH CAROLINA: 1 Ƥ Chesterfield Co., N 34.5403 W080.23182, 18.v. 2006 (S.W. Droege); [ PCYU]; VIRGINIA: 1 Ƥ Assateague I., N 37.9144 W075.3379,– 1.vii. 2006 (S.W. Droege); [ PCYU]; WEST VIRGINIA: 1 Ƥ Hampshire Co., N 39.30325 W078.4339, 29–30.v. 2004 (S.W. Droege); [ PCYU].

Etymology. The specific epithet is taken from Latin word for ‘triplet’ and refers to the close similarity of this species with L. versatum and L. callidum .

DNA Barcode. Available. Multiple sequences.

Comments. Common.

Examination of voucher material from the behavioural studies performed by Michener (1966) revealed that at least some of the bees he studied correspond to L. trigeminum and not L. versatum . The latter name has been regularly applied to three distinct but closely related species ( Gibbs 2010 b, see discussion below).


The Packer Collection at York University


University of Kansas - Biodiversity Institute


University of Colorado Museum


Department of Natural Resources, Environment, The Arts and Sport