Leptogenys corniculans

An apparent endemic to the Atlantic Forests of Bahia, Brazil.

Identification
A member of the ingens species group.

Lattke (2011) - Head rectangular in full-face view; with head in oblique anterolateral view, anterolateral cephalic margin appears flattened, eye straddling blunt crest along dorsal edge; median clypeal lobe narrow, propodeal teeth triangular and well developed; body black, legs brown.

This is an apparent endemic to the Atlantic Forests of Bahia, and quite easy to distinguish, especially on account of the well-developed propodeal teeth, which are almost as long as the second antennal segment. It would seem close to the pusilla group species on account of size, shape of the basal mandibular margin, mandibular setae, slender median clypeal lobe, small eye, transverse mesonotum and other characters, but it would be separated from the nearest pusilla group members by the Andes and the whole Amazon Basin. The well-developed propodeal spines are quite unlike any pusilla group species but even if this could be considered an autopomorphy of the species, the head shape is very unlike the pusilla species. In L. corniculans the head seems to have been partially flattened dorsoventrally close to the eye. If the head is seen in an oblique anterolateral view, a pinched aspect of the anterolateral cephalic margins becomes apparent with the eye straddling the formed blunt crest on its dorsal edge.

Distribution
This taxon is known from southeastern Brazil.

Castes
Queens and males are unknown.

Nomenclature

 *  corniculans. Leptogenys corniculans Lattke, 2011: 190, fig. 33 (w.) BRAZIL.

Worker
Metrics, holotype: HL 0.85; HW 0.53; ML 0.32; EL 0.10; SL 0.68; PW 0.50; WL 1.15; PH 0.47; PL 0.43; DPW 0.28 mm. CI 0.63; MI 0.59; OI 0.19; SI 1.28; LPI 1.08; DPI 0.65.

Head rectangular in full-face view, widest posterad of eyes, lateral cephalic margin mostly straight to weakly convex, posterior margin weakly concave, vertexal carina well developed, narrow, visible along all of posterior cephalic margin; median clypeal lobe longer than wide, apex pointed, without setae, with 2 preapical long hairs; lateral clypeal lobe narrow, weakly projecting anterad. Compound eye small, not more than 6 ommatidia in length, lens of ommatidia indistinct, eye placed laterally on head, distance from ocular midpoint to mandibular insertion greater than that from eye to mid-distance of lateral cephalic margin, eye in dorsal cephalic view weakly convex. Cephalic dorsum mostly smooth and shining except for scattered piligerous punctulae. Scape surpasses posterior cephalic border by under 2 × its apical width, antennal segments I–IV subequal in length, longer than wide, width of each segment more than one-half respective length. Scape mostly smooth and shining with scattered punctae, abundant mostly decumbent to subdecumbent pilosity, no appressed pubescence. Mandible elongate, basal and external margins subparallel, basal margin sinuate with row of 3 setae close to base; masticatory margin edentate except for apical tooth, mandibular dorsum mostly smooth and shining except for scattered piligerous punctae.

Mesosoma with mostly continuously broadly convex dorsal margin in lateral view, metanotal groove barely impressed; pronotal margin with brief, straight anterior margin and broadly convex dorsal margin; pronotum mostly smooth and shining with scattered punctae anterad, meso- and metapleuron colliculate, small rugulose area present posterad of propodeal spiracle; declivitous margin jagged anterad of tooth, propodeal tooth elongate and triangular. Mesometapleural suture distinct; metapleural-propodeal suture absent, brief ledge extends anterad of propodeal spiracle to same level of posteroventral mesopleural corner, mesopleuron subrectangular, propodeal spiracle broadly elliptical, facing posterolaterad. Width of mesonotum more than twice its length, metanotal groove distinct but finely impressed.

Petiolar node subquadrate in lateral view with vertical anterior margin half as long as posterior margin; dorsal margin convex, node highest posterad, posterior margin broadly convex. Subpetiolar process subquadrate, posterior margin longer than anterior margin. Node in dorsal view longer than wide, anterior margin broadly convex, width of anterior margin more than half the width of broadly convex posterior margin, lateral margin straight to weakly concave. Cross-section of node V-shaped, with straight lateral margins. Node mostly smooth and shining with weak colliculae lateroventrad and striae anteroventrad. Anterior margin of abdominal segment III broadly convex in lateral view, dorsal margin convex, constriction between abdominal segments III and IV well developed. Gaster mostly smooth and shining with scattered piligerous punctulae; pro- and metatibial apices without apical setae; mesotibia with single apical seta. Head and body without pubescence, only scattered pilosity. Body mostly black; mandibles, antennae, legs and gastral apex brown.

Type Material
Holotype worker. Brazil, Bahia,, Ilhéus, 1987, J.H. Delabie leg. One worker deposited in CEPEC.

Etymology
The species name alludes to the slender propodeal teeth of the ant. It is derived from the Latin for horn shaped, corniculatus.