Leptogenys transitionis

This species was collected in an isolated pine-forest patch with some litter, under a large stone almost a foot deep covering moist and loose soil.

Identification
Bharti & Wachkoo (2013) - Leptogenys transitionis most resembles the Chinese Leptogenys laozii Xu, 2000 but can be easily separated from it by the absence of pubescence on the body (extensive in L. laozii) and larger body size (TL 6.38-6.69; HW 0.88-0.92, cf. TL 4.50-5.00; HW 0.63-0.70 in L. laozii). Among the Indian Leptogenys it somewhat resembles Leptogenys jeanettei Tiwari, 2000 but can be easily distinguished by the longer-than-wide petiolar node (broader-than-long in L. jeanettei), and smooth shiny mesosomal dorsum (densely punctate in jeanettei).

Distribution based on Regional Taxon Lists
Oriental Region: India.

Nomenclature

 *  transitionis. Leptogenys transitionis Bharti & Wachkoo, 2013: 14, figs. 4-9 (w.q.) INDIA.

Worker
Holotype: TL 6.68; HL 1.36; HW 0.92; ML 0.68; EL 0.23; SL 1.41; PW 0.74; WL 2.20; PL 0.61; PDW 0.46; PH 0.69 mm. Indices: CI 68; MI 74; OI 25; SI 153; LPI 113; DPI 75.

Paratypes: Range of nine workers: TL 6.38-6.69; HL 1.29-1.36; HW 0.88-0.92; ML0.64-0.67; EL 0.21-0.23; SL 1.36-1.41; PW 0.71-0.74; WL 2.05-2.20; PL 0.57-0.61; PDW 0.43-0.46; PH 0.65-0.69 mm. Indices: CI 66-68; MI 72-73; OI 24-25; SI 151-158; LPI 113-114; DPI 73-77.

Head: Head subrectangular in full-face view, slightly wider anteriorly than posterially, posterior and lateral margins broadly convex; median clypeal lobe broad, apex bluntly rounded with single median seta, strongly carinate in middle, its anterior margin thin and translucent. Compound eye broadly convex, flattened, placed laterally, anterior to cephalic mid-length. Frontal groove shallow, reaching posterior margin of eye level; mandible elongate, basal margin convex, basal tooth reduced; masticatory margin edentate, concave; basal sulcus well developed. Scape surpasses posterior cephalic border by two-fifths of its length; third antennal segment two-thirds longer than wide, and one-third longer than second segment.

Mesosoma: Mesosoma with promesonotum forming a single broad convexity in lateral view, metanotal groove deeply impressed, dorsal propodeal margin broadly convex, twice as long as declivitous margin. Propodeal spiracle round, facing posteriorly. Promesonotal suture distinct; mesonotum subquadrate, slightly wider than long, divided in centre by a longitudinal sulcus, which is very shallow (almost absent in one specimen). Propodeal declivity subtriangular, wider posteriorly than anteriorly; posterolateral propodeal margins rounded.

Metasoma: Petiole subrectangular in lateral view, anterodorsal margin convex, curvature weak anterobasally but becoming stronger towards apex; node highest posteriorly with rounded apex, posterior margin inclined, with strong convexity basally; node broadly trapezoidal in dorsal view, longer than wide; lateral margin convex, anterior margin convex, posterior margin nearly straight or weakly convex. Subpetiolar process subquadrate, directed backwards in lateral view. Gaster elongate; a distinct constriction, with a row of short longitudinal ridges in it, separates first and second gastral segments. Tibiae without setae on external face close to apex.

Sculpture: Mandible with dorsal surface smooth, punctate laterally. Cephalic dorsum with dense punctures, which become dispersed posteriorly; clypeus smooth, laterally with some longitudinal to oblique striae. Scape with piligerous punctulae which become dense apically; funiculus densely punctulate. Mesosoma mostly smooth and shining, with sparse piligerous punctures; propleuron smooth and shining, mesopleuron with rugae on anepisternum and posteroventrally, weakly colliculate medially; metapleuron with rugulae, medially mostly smooth and shiny. Metanotal groove with cross ribs; propodeal declivity transversely striate. Node and gaster polished, smooth and shining.

Vestiture: Body with abundant suberect hairs, no appressed pubescence. Scape covered with abundant, subequal and suberect hairs.

Colour: Mandible, funiculus, apex of median clypeal lobe, legs, and apical gastral segments ferruginous brown; rest of body dark brown.

Queen
Paratype: TL 6.82; HL 1.39; HW 1.01; ML 0.75; EL 0.26; SL 1.39; PW 0.77; WL 2.13; PL 0.51; PDW 0.60; PH 0.85 mm. Indices: CI 73; MI 74; OI 26; SI 138; LPI 167; DPI 118.

Ergatogyne with the usual differences from the workers including larger eyes, 3 well developed ocelli and enlarged gaster, more than twice as wide as petiole in dorsal view. The ergatogyne is less sculptured and lighter-coloured than her worker, with a more ferruginous tint. Mandible not swollen but paler.

Etymology
The species epithet refers to the intermediate phenotype of the ergatogyne.

References based on Global Ant Biodiversity Informatics

 * Bharti H., and A. A. Wachkoo. 2013. Two new species of the ant genus Leptogenys (Hymenoptera: Formicidae) from India, with description of a plesiomorphic ergatogyne. Asian Myrmecology 5: 11-19.