Leptogenys nigricans

The locality records suggest this is a species inhabiting low land forests of the western and northwest Amazonas watershed. On account of the clearly recognizable wing stumps, this is the only other known species in the genus, besides Leptogenys langi, to have queens with wings plus the additional associated sclerites. (Lattke 2011)

Identification
Lattke (2011) - A member of the quiriguana species group. Head subquadrate in full-face view; eye dorsolaterally situated on head, occupying close to one-third lateral cephalic margin; median clypeal lobe broadly triangular, apex blunt, lacking apical setae; mandible triangular in dorsal view, external margin with weakly convex basal margin distinctly separated by basal mandibular sulcus, rest of external margin straight to broadly convex.

Distribution
Occurs in the Amazon watershed, with collection records from Brazil, Colombia and Ecuador.

Distribution based on Regional Taxon Lists
Neotropical Region: Brazil, Colombia, Ecuador.

Castes
Male unknown.

Nomenclature

 *  nigricans. Leptogenys nigricans Lattke, 2011: 205, fig. 61 (w.q.) BRAZIL.

Worker
Metrics, holotype (paratypes, n = 5): HL 1.65 (1.28–1.52); HW 1.15 (0.88–1.08); ML 0.84 (0.61– 0.78); EL 0.34 (0.27–0.30); SL 1.62 (1.18–1.48); PW 0.98 (0.78 – 0.88); WL 2.49 (1.92 – 2.33); PH 1.08 (0.81 – 0.98); PL 0.91 (0.71 – 0.84); DPW 0.71 (0.54 – 0.61) mm. CI 0.69 (0.68–0.79); MI 0.74 (0.60–0.76); OI 0.29 (0.28 – 0.31); SI 1.41 (1.29 – 1.40); LPI 1.19 (1.08 – 1.22); DPI 0.78 (0.72 – 0.78).

Head subquadrate in full-face view, slightly wider anterad than posterad, lateral margin weakly convex, posterior margin straight to weakly concave; median clypeal lobe broadly triangular, apex blunt, lacking apical setae, median area mostly smooth with striae laterad; clypeus laterally mostly smooth, lateral lobe weakly developed. Head mostly smooth and shining dorsad with scattered piligerous punctulae, punctulae denser anterad and close to eye; frontal carinae extend posterad close to mid eye height, defining narrow rugulose area. Eye dorsolaterally situated on head, occupying close to one-third lateral cephalic margin, broadly convex, closer to lateral cephalic mid-length than to mandibular insertion. Ventral face of head mostly glabrous with sparse punctae. Scape surpasses posterior cephalic border by over one-fourth it length, scape with abundant decumbent pilosity and scattered subdecumbent to suberect hairs especially apicad. Funicular segments elongate, wider apicad than basad; apical width of third antennal segment over half its length; antennal segments II–IV similar in length, IV slightly shorter. Mandible triangular in dorsal view, external margin with weakly convex basal margin distinctly separated by basal mandibular sulcus, rest of external margin straight to broadly convex; basal margin mostly convex, masticatory margin mostly straight to weakly concave, apex concave. Dorsum mostly smooth and shining with weak longitudinal strigulae and scattered punctae; PF: 4,3.

Mesosoma with promesonotal margin forming single convexity in lateral view, dorsal propodeal margin broadly convex, curving onto weakly convex declivituous margin that becomes bluntly jagged towards low rounded tooth. Metanotal groove well impressed. Mesosoma mostly smooth and shining to glabrous, mesopleuron with brief transverse lineal impression next to metathoracic spiracle; mesometapleural suture well impressed, scrobiculate; propodeal spiracle round to broadly oval, posterolaterally facing; mesonotum wider than long in dorsal view, anterior margin convex, posterior margin concave. Declivitous face medially mostly smooth and shining, weakly colliculate, especially posterad, 3–4 transverse striae present along lateral margin.

Petiolar node subquadrate in lateral view, anterior margin vertical, shorter than posterior margin, dorsal margin convex, highest posterad. Node roughly as wide as long in dorsal view, convex anterior margin more than half length of mostly straight posterior margin. Node smooth and shining, transverse section at midlength convex; anteroventral process hook shaped. Anterior postpetiolar margin vertical in lateral view, dorsal margin convex, constriction between abdominal segments III and IV weak; gaster smooth and shining with sparse punctulae. No pubescence on body, just sparse suberect hairs on mesosomal sides and dorsum. Body mostly jet black; mandible, clypeus, antennae, legs, and gastral apex brown to dark brown. Tibiae with apical seta on only on mesotibiae.

Queen
Median ocellus present, lateral ocelli present to absent, only a puncture left as trace. Anterior margin of scutum convex in dorsal view, mostly smooth and shining with sparse piligerous punctae. Tegulae, wing stumps, axillae, scutellum, and metanotum well developed. Propodeal dorsal margin weakly convex in lateral view, petiolar node anterolaterally compressed; gaster larger than in worker.

Type Material
Holotype worker. Brazil, Amazonas, Benjamin Constant & vicinity, BC-73, 22.ix.1962, W.L. Brown Jr. Deposited in the. The holotype is the middle specimen on a pin with three point-mounted workers. – Paratypes. (1) Brazil, Amazonas, Benjamin Constant & vicinity, BC-73, 22.ix.1962, W.L. Brown Jr. Two workers deposited in the MCZC. The top and bottom specimens on the same pin as the holotype. (2) Brazil, Amazonas, Benjamin Constant & vicinity, BC-3X, 18.ix.1962, W.L. Brown Jr. One worker and one queen on the same pin. Deposited in the MCZC.

Etymology
The species name alludes to the jet black color that dominates the body. It is derived from the Latin for black, nigra.