Lasioglossum (Dialictus) arantium Gibbs

Gibbs, Jason, 2011, Revision of the metallic Lasioglossum (Dialictus) of eastern North America (Hymenoptera: Halictidae: Halictini), Zootaxa 3073, pp. 1-216 : 53-56

Lasioglossum (Dialictus) arantium Gibbs , new species

( Figure 62–65 )

Holotype. Ƥ USA, Maryland, Worcester Co., Pocomoke River SF, sand dune off Old Furnace Rd., N38.19495 W075.47567, 22–23.vii.2008 (J. & C. Frye, A. Mirto); [ PCYU].

Diagnosis. Female L. arantium can be recognised by the following diagnostic combination: metasoma reddish orange ( Fig. 62 A), clypeus with distal half blackish brown ( Fig. 62 B), postgena completely lineolate, mesoscutal punctures dense throughout ( Fig. 63 ), mesepisternal punctures distinct, and metapostnotal rugae reaching posterior margin. They are superficially similar to L. pictum , which has metasoma yellowish orange and distal portion of postgena polished.

Male L. arantium can be recognised by the following diagnostic combination: head round (length/width ratio = 1.00); pronotal ridge broadly rounded; parapsidal line narrow; mesepisternum with distinct, dense punctures ( Fig. 64 A); tegula ovoid; tarsi brownish yellow; metasomal terga brown with reddish posterior margins; T2–T3 with sparse basolateral tomentum ( Fig. 64 A); T2 apical impressed area distinctly punctate; and sternal pubescence short (1 OD). They are most similar to L. miniatulum which lack tomentum on T2–T3 and have blue mesoscutal integument.

Description. FEMALE. Length 4.24–5.14 mm; head length 1.12–1.37 mm; head width 1.12–1.42 mm; forewing length 2.66–3.51 mm.

Colouration. Head and mesosoma pale green with bluish reflections, rarely blue. Labrum reddish brown to yellow. Mandible amber. Clypeus with apical half blackish brown. Antenna dark brown, flagellum with ventral surface reddish brown to yellowish brown. Tegula pale amber. Wing membrane subhyaline, venation and pterostigma yellowish brown. Legs brown, except tibial bases and apices, medio- and distitarsi, and sometimes protibia and basitarsi reddish to brownish yellow. Metasoma terga reddish orange, T4–T5 brown, terga and sterna with apical margins translucent 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 subappressed tomentum, not obscuring surface. Mesoscutum lateral margins and mesepisternum dorsally with tomentum. Metepisternum obscured by tomentum. Propodeum with moderately dense plumose hairs on lateral and posterior surfaces (2–2.5 OD). Metasomal terga with moderately dense, fine hairs. T1 acarinarial fan complete (obscure on pale background). T1 apicolaterally, T2–T3 basally and laterally, and T4 throughout with moderately dense tomentum largely obscuring surface. T2 apicolateral and T3–T4 apical margins with relatively dense fringes.

Surface sculpture. Face imbricate, punctation moderately strong. Clypeus with apical half polished, punctation moderately sparse (i=1–1.5d). Supraclypeal area with punctation moderately sparse (i=1–1.5d). Lower paraocular area and antennocular area punctation dense (i≤d). Upper paraocular area, frons and ocellocular area punctatereticulate. Gena and postgena lineolate. Mesoscutum weakly imbricate, polished submedially, punctation dense between parapsidal lines (i≤d), contiguous laterad of parapsidal line and punctate-reticulate on anterolateral portion. Mesoscutellum polished, submedial punctation sparse (i=1–3d). Axilla punctate. Metanotum punctate. Preëpisternum rugulose. Hypoepimeral area imbricate-punctate. Mesepisternum rugulose-punctate (i≤d), more polished below. Metepisternum with dorsal half rugoso-carinulate, ventral half imbricate. Metapostnotum with anastomosing rugae nearly reaching posterior margin. Propodeum with dorsolateral slope and lateral surface ruguloseimbricate, posterior surface tessellate. Metasomal terga polished, punctation fine throughout, close on basal halves (i=1–1.5d), more widely spaced on marginal zone (i=1–2d).

Structure. Head wide (length/width ratio = 0.97–1.00). Eyes convergent below (UOD/LOD ratio = 1.17–1.27). Clypeus 1/2 below suborbital tangent, apicolateral margins strongly convergent. Antennal sockets close (IAD/ OAD <0.5). Frontal line carinate, ending 2–2.5 OD below median ocellus. Gena narrower than eye. Inner metatibial spur pectinate with 2–4 branches. Metapostnotum moderately elongate (MMR ratio = 1.17–1.29), posterior margin rounded onto posterior surface. Propodeum with oblique carina obscure, lateral carina weak, not reaching dorsal margin.

MALE. Similar to female except for the usual secondary sexual characters and as follows. Length 3.88–4.50 mm; head length 1.08–1.23 mm; head width 1.08–1.23 mm; forewing length 3.13–3.19 mm.

Colouration. Mandible yellow on apical half. Flagellum with ventral surface reddish brown, pedicel and F1 brownish yellow ventrally. Pterostigma brown. Base and apex of tibiae brownish yellow. Legs brown, except tarsi pale brownish yellow. Metasomal terga brown, apical impressed areas reddish brown.

Pubescence. Face below eye emargination with scattered tomentum partially obscuring surface, dense on lower paraocular area. T2–T3 with scattered basolateral tomentum. Metasomal sterna sparsely pubescent, S3–S4 with small apicolateral tufts (1 OD).

Surface sculpture. Mesoscutal punctation between parapsidal line relatively sparse (i=1–2d). Mesepisternum distinctly punctate.

Structure. Head wide (length/width ratio = 1.00). Eyes strongly convergent below (UOD/LOD ratio = 1.48– 1.59). Clypeus 1/2 below suborbital tangent, apicolateral margins weakly convergent. Antennal sockets distant (IAD/OAD> 1.4). Frontal line carinate, ending 1.5 OD below median ocellus. Pedicel shorter than F1. F2 length 1.8–2.0X F1. F2–F10 moderately elongate (length/width ratio = 1.60–1.89). Metapostnotum elongate (MMR ratio = 1.00–1.09), posterior margin rounded onto posterior propodeal surface.

Terminalia . S7 with median lobe relatively wide, apex truncate. S8 with apicomedial margin weakly convex. Gonobase with ventral rim distinctly separated. Gonostylus small, dorsal setae elongate. Retrorse lobe moderately elongate, rounded apically.

Range. Coastal regions of Maryland and New Jersey ( Fig. 66 ). USA: MD, NJ.

Paratypes. USA: MARYLAND: 9 ƤƤ Worcester Co., Pocomoke River SF, sand dune off Old Forest Rd., N38.18584 W075.49646, 22–23.vii.2008 (J. & C. Frye, A. Mirto); 1 Ƥ Worcester Co., Pocomoke River SF, sand dune off Old Furnace Rd., N38.19492 W075.47759, 2–3.iv.2008 (J. & C. Frye, A. Mirto); 4 ƤƤ Worcester Co., Pocomoke River SF, sand dune off Old Furnace Rd., N38.19495 W075.47567 ,, 22–23.vii.2008 (J. & C. Frye, A. Mirto); 2 ƤƤ Worcester Co., Pocomoke River SF, sand dune off Old Furnace Rd., N38.19495 W075.47567 ,, 5–6.v.2008 (J. & C. Frye, A. Mirto); 10 ƤƤ Worcester Co., Pocomoke River SF, sand dune off Sand Rd., N38.18845 W075.49200, 5–6.v.2008 (J. & C. Frye, A. Mirto); 20 ƤƤ Worcester Co., Pocomoke River SF, sand dune off Sand Rd., N38.18845 W075.49200, 22–23.vii.2008 (J. & C. Frye, A. Mirto); [CUIC, PCYU]; NEW JERSEY: 1Ƥ Atlantic Co., N39˚37ʹ W074˚47ʹ, 17.vi.2003 (B. Ahlstrom); 1Ƥ Atlantic Co., N39˚41ʹ W074˚46ʹ, 6.vi.2003 (R. Winfree); [PCYU]

Etymology. The specific epithet comes from a Latin word for orange and refers to the colour of the metasoma.

DNA Barcode. Available. Multiple sequences.

Comments. Uncommon.

Aside from the strikingly different colour patterns, L. arantium is morphologically most similar to L. miniatulum . DNA barcodes of these two species are nearly identical. Both species may have preferences for coastal areas. The known ranges of these two species are limited to a relatively small geographic area. Additional sampling in the intervening areas will be important for elucidating the relationship between these two species. Although L. arantium may be difficult to distinguish from L. pictum using the key, the ranges of the two species do not seem to overlap.

Figures

FIGURE 62. Lasioglossum arantium Gibbs female, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 63. Lasioglossum arantium Gibbs female, dorsal view of mesosoma.

FIGURE 64. Lasioglossum arantium Gibbs male, (A) lateral habitus, (B) face. Scale bars = 1 mm.

FIGURE 65. Lasioglossum arantium Gibbs male, dorsal view of mesosoma.

FIGURE 66. Distribution map of Lasioglossum arantium (circles) and L. ascheri (squares).