Leptogenys oaxaca

The specimens were collected alongside a stream. Valle Nacional is located at 17°46′ N 96°18′ W, and on a map cursory exploration of points roughly 6 miles (9.7 km) south of Valle Nacional show a range of altitudes from 160 to 500 meters.

Identification
Key to Leptogenys of the New World

Lattke (2011) - A member of the elongata species group. Head, mesosoma and petiole finely striate to rugulose, opaque; node in lateral view with anterior and dorsal margins forming continuous convexity; third antennal segment almost as long as combined lengths of segments four and five; basal margin of mandible shuts tight against clypeus, basal part of masticatory margin with prominent concavity, and brief pre-apical margin; median clypeal lobe broad.

This species is apparently close to Leptogenys honduriana because of similarities in size, sculpturing, head shape, eye position, and the broad median clypeal lobe, besides the presence of cuticular iridescence in both. The mandible in L. honduriana is recognizably triangular but has a sinuate and long masticatory border, about as long as the basal border, with a weak concavity after the basal angle followed by a weak convexity, and then a weak pre-apical concavity before the apical tooth. Because of the mandibular shape in L. honduriana, the unique concavity of L. oaxaca was interpreted as forming part of the masticatory margin and not part of the basal margin. L. honduriana has a fine, ventral mesopleural carina, which is lacking or barely discernible in L. oaxaca, and the median clypeal lobe in L. honduriana ends in a blunt obtuse angle.

Distribution
This taxon was described, and is only known, from (southern) Mexico.

Castes
Queens and males are unknown.

Nomenclature

 *  oaxaca. Leptogenys oaxaca Lattke, 2011: 162, fig. 19 (w.) MEXICO.

Worker
Metrics, holotype (paratype): HL 1.95 (2.15); HW 1.95 (1.85); ML 1.50 (1.55); EL 0.40 (0.40); SL 2.45 (2.25); PW 1.35 (1.25); WL 3.60 (3.50); PH 1.30 (1.25); PL 1.20 (1.15); DPW 0.85 (0.85) mm. CI 1.00 (0.86); MI 0.77 (0.84); OI 0.21 (0.22); SI 1.26 (1.22); LPI 1.08 (1.09); DPI 0.71 (0.74).

Head in full-face view slightly wider anterad than posterad, posterior margin convex, lateral margin broadly convex, both margins forming continuous curve without sharp curvatures or angles. Median clypeal process apically truncate, lateral lobes present; anterior clypeal margin without translucent lamella. Eye dorso-laterally placed, not touching lateral cephalic margin in cephalic full-face view, slightly closer to median cephalic length than to mandibular insertion, length close to one-fourth that of lateral cephalic margin. Scape surpasses posterior cephalic border by approximately one-third its length; third antennal more than 2 x length of second, almost as long as combined lengths of fourth and fifth segments. Head finely striate to rugulose, opaque; clypeus shining; basal margin of mandible shuts tight against clypeus, basal angle blunt, followed by abrupt but even, long concavity, more or less parallel to cephalic dorsum; concavity followed by pre-apical angle and brief pre-apical margin that follows a ventrally directed angle; mandibular dorsum with scattered piligerous punctae and fine, longitudinal parallel strigulae. Closed mandibles form rounded aperture resembling a wire-stripper. Basal third of external mandibular margin straight, the rest sharply convex. Posterior labium smooth and shining, maxilla with curved carinae; ventral cephalic surface shining and smoother than dorsal surface; palpal formula 4,3.

Mesosoma with dorsal margin divided by deeply impressed metanotal groove in lateral view, posterior mesonotal margin forming sharp angle; pronotal dorsal margin convex, mesonotal margin broadly convex to straight; propodeal dorsal margin convex, more than twice as long as declivity; short propodeal denticle projects posterad at spiracular height, spiracle round to oval. Meso-metapleural suture distinctly cleft, lateral propodeal and metapleural surface forming convexity; metapleural-propodeal suture ill-defined, propodeal declivity with transverse strigae. Mesonotum longer than wide, transversely strigulose. Pronotal disc mostly with slightly diverging rugulae, rugulae becoming transverse along posterior margin. Propleuron with oblique parallel, strigae; mesopleuron transversely strigulate, strigulae extending to mesosternum, no carina separates mesopleuron from mesosternum. Anterior mesosternal lobe low, height less than one-fourth mesocoxal height; metasternal lobe apically truncate, height more than one-fourth metacoxal height.

Anterior and dorsal petiolar margins in lateral view form continuous convexity; posterior margin slightly sinuate; sculpture fine strigulae, opaque. Node in dorsal view longer than wide, anterior margin straight and wider than half the posterior margin; posterior node face relatively smooth with faint transverse strigulae, shining. Gaster shining with abundant piligerous punctulae. Stridulitrum visible on pretergite of abdominal segment IV. Body with abundant appressed pilosity and standing hairs; scape with appressed pilosity and no standing hairs. Head, mesosoma, and node dark brown to black, gaster brown to dark brown; mandible, scape, metacoxa dark brown; funiculus, and rest of legs ferruginous. Protarsal claws as densely pectinate as meso and metatarsal claws. Some parts of mesosoma, cephalic ventrum and coxa may have discrete blue iridescence. Protarsal segments ending with two pairs of fine setae.

Type Material
Holotype worker. Mexico, Oaxaca, 6 miles S Valle Nacional, 20.vii. – 01.viii.1971, A. Newton collector. One worker deposited in the. – Paratype. One worker with same data as the holotype, deposited in the MCZC.

Etymology
The species name alludes to the Mexican State of Oaxaca, in which the type locality is found.