Leptogenys langi

These ants have been captured in mature rainforest in clay soil turned over by a tree fall, and at base of a large dead tree, in humus below leaf litter. This species, Leptogenys nigricans, and an undescribed species from Texas (Cokendolpher et al. 2009) are the only New World species known to have winged queens. (Lattke 2011)

Identification
Key to Leptogenys of the New World

Lattke (2011) - A member of the langi species group. Head slightly elongate in full-face view; eye convex, occupying less than one-fourth of lateral margin; scape surpasses posterior cephalic border by more than 2 apical widths; mandibles when closed leave gap at base of clypeal lobe almost one-half their median width; mandible subparallel, weakly widens apicad. Node elongate in dorsal view; lateral margins semiparallel, just slightly divergent posterad; anterior margin rounded, almost as wide as posterior margin; posterior margin straight to slightly convex.

Distribution
Known from Amazon-Orinoco watershed, Brazil, Bolivia, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname and Venezuela.

This taxon was described from Guyana.

Castes
Male unknown.

Nomenclature

 *  langi. Leptogenys (Lobopelta) langi Wheeler, W.M. 1923d: 5, fig. 1 (w.q.) GUYANA. See also: Lattke, 2011: 179.

Wheeler’s description of L. langi differs from the Brazilian and Peruvian samples in the more elongate third antennal segment, and smaller ventral petiolar process. The head is described and illustrated as posteriorly narrower than anterad, but this is not apparent in a syntype depicted on the website nor in the  syntypes. The curvature of the pygydium may vary when comparing specimens, but this depends on the degree of gastral extrusion. (Lattke 2011)

Worker
Lattke (2011) - Metrics (n = 5): HL 0.80 – 0.87; HW 0.53 – 0.57; ML 0.38 – 0.43; EL 0.13 – 0.15; SL 0.70 – 0.75; PW 0.45 – 0.48; WL1.12 – 1.22; PH 0.47 – 0.50; PL 0.43 – 0.45; DPW 0.33 – 0.35 mm. CI 0.65 – 0.67; MI 0.70 – 0.76; OI 0.24 – 0.28; SI 1.29 – 1.36; LPI 1.04 – 1.15; DPI 0.74 – 0.81.

Head slightly elongate in full-face view; posterior margin straight to slightly concave; lateral margin broadly convex; eye convex, occupying less than one-fourth of lateral margin, lens of each ommatidium distinctly convex, but indistinct at perimeter, tending to fuse; clypeal margin laterally sinuate, converging anterad to slender and acutely pointed median lobe. Median cephalic sulcus shallow, barely impressed, its width about one-third the length of frontal carinae. Scape surpasses posterior cephalic border by more than 2 apical widths; basal funicular segments subequal in length, each width more than one-half the length; basal funicular segments with strong constriction. Mandibles when closed leave gap at base of clypeal lobe almost one-half their median width; mandible subparallel, weakly widens apicad; basal margin convex with 3 stout hairs at mid-length; masticatory margin with angle or small pre-apical denticle, masticatory margin edentate, slightly sinuate; dorsum smooth and shining, basal sulcus well developed. PF: 4,3. Ventral cephalic face smooth and shining; hypostomal tooth triangular, not visible in dorsal cephalic view; maxillae and labium smooth and shining.

Mesosoma with promesonotal margin forming single convexity in lateral view; metanotal groove well impressed; propodeal dorsal margin broadly convex to straight; declivity straight to broadly convex, with lobe-like denticle at spiracular height. Pro- and mesosternum smooth and shining. Mesosoma mostly smooth and shining; ventral pronotal groove fine; mesometapleural suture well impressed; propodeal spiracle oval, facing posterolaterally. Mesonotum with curved anterior margin in dorsal view, posterior margin transverse and straight; propodeal declivity mostly smooth and shining with single transverse carina uniting base of propodeal denticles.

Petiole with vertical anterior margin not higher than half posterior margin in lateral view, vertical and dorsal margins form curve, highest posterad, posterior margin slightly convex. Anterior postpetiolar face flattened, anterior margin mostly straight, reaching three-fourths height of posterior node margin. Subpetiolar process with brief convex anterior margin in lateral view, less than half the length of posterior margin, posterior margin concave, ventral margin straight. Node elongate in dorsal view; lateral margins semi-parallel, just slightly divergent posterad; anterior margin rounded, almost as wide as posterior margin; posterior margin straight to slightly convex. Gaster smooth and shining, constriction well marked; pygidial margin in lateral view broadly convex anterad, curvature becoming sharper close to posterior apex with posterior one-fourth broadly convex to straight. Body has sparse decumbent to semi-erect hairs, no pubescence. Procoxa smooth and shining in lateral view; antennae, mandibles, legs and gastral apex yellow to brownish-yellow; body ferruginous brown. Tibial apices wanting setae; posterior margin of tarsi has 2 pairs of setae.

Queen
Metrics: HL 1.00; HW 0.70; ML 0.44; EL 0.20; SL 0.88; PW 0.64; WL 1.54; PH 0.66; PL 0.50; DPW 0.44 mm. CI 0.70; MI 0.63; OI 0.29; SI 1.26; LPI 1.32; DPI 0.88. Head with 3 ocelli on posterior frons; compound eye proportionally larger than worker, more convex; mesopleuron with transverse mesopleural suture that curves sharply ventrad briefly before disappearing; anteroventral mesopleural carina lacking; katepisternum 2 x length of anepisternum. Mesoscutum as wide as long in dorsal view, anterior margin wider than posterior margin; anterior margin convex, lateral margin concave; metanotum transverse in dorsal view, arched, anterior and posterior margins parallel; axillae separated from scutellum by shallow sulcus. Wings present. Petiolar node as wide as long in dorsal view, posterior margin of node wider than anterior margin.

Type Material
Syntype workers and queens: Guyana (= British Guiana), Kamakusa, 2.xi.1922 (H. Lang) [examined].

Additional References

 * [[Media:Lattke 2011.pdf|Lattke, J. E. 2011. Revision of the New World species of the genus Leptogenys Roger (Insecta: Hymenoptera: Formicidae: Ponerinae). Arthropod Systematics and Phylogeny 69:127-264. [2011-12-13] PDF]]