Lasioglossum (Dialictus) gemmeum, Gibbs & Bass & Morgan, 2022

Gibbs, Jason, Bass, Amber & Morgan, Katherine, 2022, Habralictus and Lasioglossum of Saint Lucia and Saint Vincent and the Grenadines, Lesser Antilles (Hymenoptera, Apoidea, Halictidae), ZooKeys 1089, pp. 125-167 : 125

Lasioglossum (Dialictus) gemmeum sp. nov.

Figs 20 , 21

Holotype.

♀. Saint Vincent, St. George Parish, 5-10.X.1991, leg. R.E. Woodruff, Malaise trap (FSCA).

Paratypes.

SVG • Saint Vincent• St. George Parish • Rivulet Agr. Sta., 27-30-IX-1991, leg. R.E. Woodruff, Malaise trap (1 ♂); 5-10-X-1991, leg. R.E. Woodruff, Malaise trap (2 ♀ FSCA) • "24 // W. Indies / 99-331 // Dialictus -not Halictus gemmatus det G.C. Eickwort" (1 ♀ NHMUK). One leg, both forewings and one hind wing missing. "69 // W. Indies 99-331 // Halictus gemmatus Smith Ashm // Dialictus -not Halictus gemmatus det G.C. Eickwort" (NHMUK). In good condition, two submarginal cells in both wings (1 ♀ NHMUK) • St Vincent, Majorea, VIII.1972 (2 ♂ SEMC).

Halictus gemmatus : Ashmead (1900: 218, 219, 303) key, distribution record (in part); Friese (1909: 37) catalogue. Non Halictus gemmatus Smith, 1853.

Dialictus gemmatus : Moure and Hurd (1987: 101) catalogue (in part); Moure (2007: 849) catalogue (in part). Non Dialictus gemmatus Smith, 1853.

Diagnosis.

Females of L. gemmeum are easily recognised by their orange-red metasoma and small size (~ 3.5 mm long). No other L. (Dialictus) in the Caribbean is known to have such a brightly coloured metasoma, although some L. (Habralictellus) do. Males can be distinguished from other SVG L. (Dialictus) by the elongate (1.5-2 MOD), pectinate setae on S5-S6. Other SVG L. (Dialictus) have short (1 MOD), simple setae on S5-S6, which contrast with plumose setae on preceding sternites.

Description.

Female (n = 5). Length 3.3-3.6 mm; head length 1.03-1.11 mm; head width 1.08--1.19 mm; intertegular distance 0.71-0.84 mm; wing length 1.38-1.60 mm.

Colouration. Head and mesosoma dull metallic blue-green to golden-green, except as follows. Labrum reddish brown. Mandible yellow-orange with brown base and red apex. Clypeal apex dark brown. Antenna dark brown, flagellum with ventral surface reddish brown. Pronotal lobe yellow-orange. Tegula amber. Wing membrane hyaline with dark setae, venation pale brown. Legs amber-brown. Metasomal terga orange.

Pubescence. Dull white. Relatively sparse erect setae throughout, without tomentum, except on gena near eye, pronotal dorsolateral angle and lobe. Metasomal T1 with fan virtually absent, no erect setae medially. T2 without apical fimbriae, T3-T4 with only sparse fine setae on apical impressed areas. Scopa well developed on hind leg and metasomal sterna.

Surface sculpture. Face imbricate, punctation moderately fine. Clypeal punctation moderately sparse (IS = 1-s PD), denser proximally (IS = 1 PD), surface smooth distally. Supraclypeal area with punctures moderately sparse (IS = 1-2 PD), weakly imbricate in centre. Lower paraocular area punctation dense (IS ≤ PD). Upper paraocular area and frons reticulate-punctate (IS <PD). Ocellocular area punctate (IS ≤ PD). Gena and postgena punctate-imbricate, sculpturing weak on postgena. Mesoscutum weakly imbricate, polished submedially; punctation moderately coarse, dense laterad of parapsidal lines, posterior portion (IS <PD), sparsest submedially (IS = 1-2 PD), mesoscutellum similar with submedial impunctate area (IS = 1-3 PD). Metanotum finely punctate. Preëpisternum finely reticulate rugulose. Hypoepimeral area finely punctate. Mesepisternum below scrobe punctate (IS ≤ d), polished. Metepisternum dorsal 1/3 lineolate, ventral portion reticulate-imbricate. Metapostnotum medially with irregular carinulae reaching 2/3 distance to imbricate posterior margin, dorsolateral slope imbricate. Propodeum posterior and lateral surfaces weakly imbricate. Metasomal terga polished, finely coriarious basally, weakly coriarious on apical impressed margin of T3; punctation sparse (IS = 2-3 PD) on basal half, indistinct, sparser on apical impressed areas, T1-T2 apical impressed areas nearly impunctate. Metasomal sterna coriarious and finely, sparsely punctate (IS = 2-4 PD).

Structure. Face relatively short (length/width ratio = 0.82 ± 0.01 SD). Eyes weakly convergent below (UOD/LOD ratio = 1.29 ± 0.19 SD). Clypeus 2/3 below suborbital tangent, apicolateral denticles low rounded knobs. Gena narrower than eye. Hypostomal carinae subparallel. Pronotal dorsolateral angle obtuse. Pronotal ridge rounded, interrupted by sulcus. Mesoscutum length/width ratio 0.82 ( ± 0.02 SD); mesoscutum/mesoscutellum length ratio 2.72 ( ± 0.2 SD); mesoscutellum/metanotum length ratio 1.75 ( ± 0.06 SD); metanotum/metapostnotum length ratio 0.64 ( ± 0.03 SD). Tegula ovoid. Submarginal cells two or three, veins 1r-sm, 2rs-m and 2m-cu distinctly weak. Distal hamuli arranged 2-1-2. Inner metatibial spur pectinate, with two or three branches not including apex of rachis, proximal branch much longer than width of rachis. Metapostnotum narrowly rounded onto posterior propodeal surface. Propodeum with lateral carina reaching 1/2 distance dorsal margin; oblique carina indistinct. Metasoma ovoid, T2-T4 impressed areas medially ~ 1/2 longitudinal length of basal area.

Male (n = 3). Length 3.3-3.5 mm; head length 1.00-1.08 mm; head width 1.00-1.11 mm; intertegular distance 0.67-0.79 mm. Similar to female with usual sex-associated modifications.

Colouration. Head and mesosoma green to golden green. Clypeal apex reddish brown. Labrum reddish brown. Mandible brown, orange apically. Flagellum reddish brown, sometimes orange ventrally. Pronotal lobe reddish brown to orange. Tegula orange. Wing membrane hyaline, veins brown to dark brown. Legs reddish brown with femur-tibia joints, base and apex of tibiae, and tarsi orange. Metasoma reddish brown.

Pubescence. Body sparse pilosity, dull white to faintly yellowish. Tomentum moderately dense on lower paraocular area, sparse on clypeus, dense on pronotal lobe. Mesoscutal pilosity thin. Sternal pilosity short (1.0-1.5 OD), densely plumose, dense, erect. Wing setae dark, short, sparse.

Surface sculpture. Clypeal punctures dense (IS ≤ 1 PD), interspaces polished. Supraclypeal punctures sparse (I = 1-2 PD), interspaces polished. Paraocular area punctures dense (IS ≤ 1 PD), interspaces shiny. Frons punctate-reticulate. Gena punctate-imbricate, postgena sculpture punctate-imbricate. Tegula mostly impunctate. Mesoscutal punctation sparse (IS = 1-3 PD), becoming dense marginally (IS = 1-1.5 PD), interspaces shiny. Mesoscutellar punctation sparse (IS = 1-2 PD). Metanotum punctate. Metapostnotum with incomplete carinulae, margin shiny to weakly imbricate. Pre-episternum sculpture punctate. Hypoepimeral area distinctly punctate IS ≤ 1 PD), interspaces polished. Mesepisternum distinctly punctate (IS ≤ 1 PD), interspaces shiny. Metepisternum lineate dorsally, weakly rugulose ventrally. Propodeal lateral face weakly imbricate-punctate, dorsolateral slope punctate. Propodeal posterior face sculpture polished-punctate. T1 anterior face polished. T1 dorsal surface sparse (IS = 2-6 PD), interspaces shiny. T2 disc punctures sparse (IS = 1-2.5 PD), failing well before premarginal line, interspaces shiny, apical impressed area impunctate, interspaces shiny.

Structure. Face length/width ratio 0.84 ( ± 0.03 SD). F1: pedicel length ratio 0.77-1.00. F2:F1 length ratio 1.76-1.89. Gena narrower than eye. Hypostomal carinae parallel. Pronotal angle obtuse. Mesoscutum length/width ratio 0.0.8 ( ± 0.02 SD); mesoscutum/mesoscutellum length ratio 2.51 ( ± 0.03 SD); mesoscutellum/metanotum length ratio 2.04 ( ± 0.25 SD); metanotum/metapostnotum length ratio 0.59 ( ± 0.07 SD). Propodeum lateral carina nearly halfway to dorsal margin; oblique carina absent. Tegula ovoid. Forewing with two or three submarginal cells. Metatibial spurs ciliate. Metasoma slender, parallel sided.

Etymology.

The specific epithet is a Latin adjective in the nominal singular meaning glittering.

Taxonomic notes.

Ashmead (1900) recorded three specimens of this species as Halictus gemmatus from the Leeward and Windward sides of St. Vincent. Comparison of two of his specimens to the type of H. gemmatus from Jamaica, indicated that they were quite distinct. Both specimens have labels attached from George Eickwort indicating it is not Halictus gemmatus . One of these is missing both forewings and the other has vein 1rs-m missing in both wings. The three other females have 1rs-m present, but the single male paratype has 1rs-m absent in the left wing and present in the right wing. Lasioglossum gemmatum is a member of the Lasioglossum gemmatum species complex (also known as the Lasioglossum parvum or Lasioglossum tegulare species complex; Ellis 1914; Gibbs 2009, 2018), but L. gemmeum does not appear to be a member of this group.

Figures

Figure 20. Lasioglossum (Dialictus) gemmeum sp. nov., holotype female A dorsal habitus B head, frontal view C lateral habitus.

Figure 21. Lasioglossum (Dialictus) gemmeum sp. nov., paratype male A dorsal habitus B head, frontal view C lateral habitus.