Lasioglossum (Dialictus) callidum (Sandhouse)

Gibbs, Jason, 2010, Revision of the metallic species of Lasioglossum (Dialictus) in Canada (Hymenoptera, Halictidae, Halictini) 2591, Zootaxa 2591 (1), pp. 1-382 : 84-88

Lasioglossum (Dialictus) callidum (Sandhouse)

( Figures 82A–E , 83A–H )

Halictus (Chloralictus) callidus Sandhouse, 1924: 34 . ♂.

Holotype. ♂ USA, Virginia, East Falls Church , 20.vii, on Daucus carota (S.A. Rohwer) ; [ NMNH: 26436]. Examined.

Taxonomy. Michener, 1951: Lasioglossum (Chloralictus) callidum , p. 1112 (catalogue); Mitchell, 1960: Dialictus callidus ♂, p. 385, D. versatus ♂ (misdet.), p. 428 (redescription); Krombein, 1967: Lasioglossum (Dialictus) callidum , p. 462 (catalogue); Hurd, 1979: Dialictus callidus , p. 1965 (catalogue); Moure & Hurd, 1987: Dialictus callidus , p. 94 (catalogue).

Diagnosis. Both sexes of L. callidum and the south central USA species L. connexum (Cresson) can be recognised by their very wide protrochanters ( Figs. 82E , 83D ). Females of both species can be further distinguished by the strongly curved dorsal margin of the mandible at midlength ( Fig. 82D ) and the wide head with a weakly protruding clypeus ( Fig. 82C ). Males of both can be further recognised by the distinct punctation of the metasomal terga apically impressed areas. Both sexes of L. connexum , unlike L. callidum , have shining, polished and distinctly punctate mesepisternum and the ventral margin of the protrochanter is strongly convex. Lasioglossum callidum is also similar to L. versatum which lacks the curved mandible and wide protrochanter.

Description. FEMALE. Length 5.19–6.45 mm; head length 1.48–1.85 mm; head width 1.61–1.99 mm; forewing length 3.60–4.88 mm.

Colouration. Head and mesosoma green with golden reflections to bluish green. Clypeus with apical half blackish brown and basal half bronze. Antenna dark brown, flagellum with ventral surface dark brown to dull brownish yellow. Tegula reddish brown to translucent amber. Wing membrane subhyaline, venation and pterostigma amber. Legs brown, medio- and distitarsi reddish to yellowish 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 dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with moderately dense, fine setae. T1 acarinarial fan sparse with wide dorsal opening, intermingled with erect hairs. T2–T3 with basolateral tomentum, forming narrow basal band on T3. T4 with tomentum partially obscuring much of disc. T2 apicolateral margin and T3–T4 apical margins with very sparse fringes.

Surface sculpture. Face imbricate. Clypeus polished, punctation dense (i≤d). Supraclypeal area with punctation moderately dense(i=1–2d). Lower paraocular area punctation dense (i≤d). Antennocular area punctation moderately dense (i<1.5d). Upper paraocular area and frons punctation contiguous. Ocellocular area punctation dense, minute (i≤d). Gena lineolate. Postgena imbricate. Mesoscutum weakly imbricate-tessellate, punctation moderately dense on medial portion of disc (i=1–1.5d), dense laterad of parapsidal lines (i≤1d) and reticulate on anterolateral portions. Mesoscutellum similar to mesoscutum, submedial punctation moderately dense (i=1–2d). Axilla densely punctate. Metanotum ruguloso-imbricate. Preëpisternum rugulose. Hypoepimeral area imbricate. Mesepisternum dorsal half ruguloso-imbricate, obscurely punctate, ventral half imbricate. Metepisternum with dorsal third rugoso-striate and ventral portions imbricate. Metapostnotum incompletely rugoso-striate, posterior margin imbricate. Propodeum with dorsolateral slope imbricate, lateral surface imbricate-tessellate, posterior surface imbricate. Metasomal terga polished except apical impressed areas weakly coriarious, punctation fine and close throughout (i=1–1.5d).

Structure. Head wide (length/width ratio = 0.90–0.93). Eyes weakly convergent below (UOD/LOD ratio = 1.19–1.22). Clypeus 1/3 below suborbital tangent, apicolateral margins strongly convergent. Antennal sockets somewhat close (IAD/OAD <0.5). Frontal line carinate, ending 2 OD below median ocellus. IOD less than OOD. Gena narrower than eye. Procoxa unmodified. Protrochanter very broad, nearly as wide as long. Metapostnotum moderately elongate (MMR ratio = 1.29–1.36), posterior margin weakly rounded onto posterior surface. Propodeum with oblique carina weak, lateral carina divergent, not reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length. 5.86– 6.71 mm; head length 1.61–1.92 mm; head width 1.61–1.97 mm; forewing length 3.84–4.58

Colouration. Flagellum with ventral surface brownish yellow. Tegula pale amber to reddish brown. Wing membrane subhyaline, venation and pterostigma reddish brown. Medio- and distitarsi pale brownish yellow.

Pubescence. Clypeus, supraclypeal area, upper paraocular area, and lower frons with moderately dense tomentum partially obscuring surface. Lower paraocular area with dense tomentum obscuring surface. T2–T6 with sparse basolateral tomentum. S2–S5 apicolateral portions moderately dense hairs (i=1–1.5d).

Surface sculpture. Clypeal punctation dense (i<d). Mesepisternum more strongly rugulose. Metapostnotum rugoso-striate. Propodeum with dorsolateral slope and lateral and posterior surface rugose. Metasomal terga with punctation deep and distinct throughout (i=1–2.5d).

Structure. Head wide to round (length/width ratio = 0.96–1.00). Eyes strongly convergent below (UOD/ LOD ratio = 1.37–1.52). Clypeus 2/3 below suborbital tangent, apicolateral margins subparallel. Antennal sockets distant (IAD/OAD> 1.1). Frontal line carinate, ending 2 OD below median ocellus. Pedicel shorter than F1. F2 length 1.5X F1. F2–F10 elongate (length/width ratio = 1.43–1.62). Protrochanter 1.8 times longer than wide. Metapostnotum moderately elongate (MMR ratio = 1.12–1.25), posterior margin weakly angled onto posterior surface. Propodeum with oblique carina virtually absent, lateral carina weak, not reaching dorsal margin.

Terminalia . S7 with median lobe narrowly acuminate, sides weakly convergent, apex rounded ( Fig. 83G ). S8 with apicomedial margin weakly convex ( Fig. 83G ). Genitalia as in Fig. 83E–F . Gonobase with ventral arms thick, narrowly separated. Gonostylus small, dorsal setae elongate. Retrorse lobes elongate, narrow, apically recurved.

Range. Ontario south to Georgia, west to Colorado ( Fig. 84 ).

Additional material examined. CANADA: ONTARIO: 1♀ Iona , 25.v.1962 (G. Knerer); [ ROM] ; USA: COLORADO: 1♀ Boulder Co., N39°56´25.2´´ W105°13´33.1´´, 23.vi.2004 (Kearns & Oliveras); [ PCYU] ; GEORGIA: 1♀ Clarke Co., State Bot. Gard. 11.iv.2006 (J. Hanula & S. Horn); [ PCYU] ; MISSISSIPPI: 1♀ Jackson Co., N30.5297 W088.6942, 4–5.vi.2005 (S.W. Droege) ; MISSOURI: 2♀ Newton Co., Diamond Grove Prairie , 20.vi.2005 (Arduser) ; NEBRASKA: 4♀ Douglas Co., N41.2796 W095.9073, 10.v.2007 (S.W. Droege) ; NORTH CAROLINA: 4♀ E of Charlotte, Hwy 24/27, N35.24474 W080.53715, 10.viii.2006 (C. Sheffield) ; SOUTH CAROLINA: 2♀ Okanee Co., nr Walhalla , N34.80472 W083.14587, 9.viii.2006 (J. Gibbs) ; 4♀ Chesterfield Co., N34.6059 W080.24994, 18–19.v.2006 (S.W. Droege) ; 2♀ Okanee Co., nr Walhalla , N34.81283 W083.13679, 9.viii.2006 (J. Gibbs) ; 2♂♂ Sandhills NWR , N34.6012 W080.2581, 25.x.2006 (L. Housh); [ PCYU] ; TENNESSEE: 1♀ Great Smoky Mountain N.P., Cades Cove, Mill Creek , N35.58276 W083.8371, 5.viii.2006 (J. Gibbs); [ GSNP] ; 1♀ nr Gatlinburg, Hwy 321, N35.75988 W083.3615, 8.viii.2006 (J. Gibbs) ; VIRGINIA: 3♀ Assateague I., N37.9124 W075.359, 1–2.vii.2006 (S.W. Droege); [ PCYU] .

Floral records. Many floral records for this species in the literature may have been listed under L. versatum (see below). APIACEAE : Apium graveolens dulce , Daucus carota , ASTERACEAE : Solidago , FABACEAE : Amorpha fruticosa ; Melilotus , POLYGONACEAE : Fagopyrum , SALICACEAE : Salix .

Comments. Rare in Canada. Common in parts of the Eastern USA excluding the New England states. The species described as L. versatum by Mitchell (1960), recognisable by the distinctly wide protrochanter and strongly curved mandible, clearly do not match the lectotype of Halictus versatus . The holotype of L. callidum has wide protrochanters and matches the male of L. versatum sensu Mitchell. The male of L. versatum has narrower, nearly cylindrical protrochanters. Although the ‘true’ L. versatum can be distinguished morphologically from L. callidum , the DNA barcodes of these two do not differ by even a single nucleotide. Morphologically L. callidum shares multiple unusual traits in common with L. connexum and is presumably sister species to that species rather than L. versatum .

Figures

FIGURE 82. Lasioglossum callidum (Sandhouse). Female (A) lateral habitus; (B) dorsal habitus; (C) face; (D) mandible; (E) protrochanter. Scale bars, A–C = 1 mm.

FIGURE 83. Lasioglossum callidum (Sandhouse). Male (A) lateral habitus; (B) dorsal habitus; (C) face; (D) protrochanter; (E) ventral view of genital capsule; (F) dorsal view of genital capsule; (G) S7, S8; (H) T1, T2. Scale bars, A–C = 1 mm, G = 0.5 mm.

FIGURE 84. Distribution of Lasioglossum callidum (light grey) and L. cattellae (dark grey).