Aenictus stenocephalus

The type specimens were collected with pitfall traps in a natural forest (dry evergreen forest and grassland), and non-type specimens from an agricultural area near a natural forest in northeastern Thailand. (Jaitrong et al. 2010)

Identification
Jaitrong et al. (2010) - This species is easily distinguished from other species of the group by the almost entirely smooth and shiny body together with angulate propodeal junction. The other important characteristics are the exceptionally narrow head with long antennal scape, subrectangular petiole, only weakly convex pronotum, and almost rudimentary subpetiolar process (but with an acutely angulate anteroventral corner).

A member of the wroughtonii group.

Key to Aenictus species groups

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Nomenclature

 *  stenocephalus. Aenictus stenocephalus Jaitrong & Yamane, in Jaitrong, et al. 2010: 41, figs. 13-15 (w.) THAILAND.

Worker
Holotype, three paratype, and one non-type workers (n = 5): TL 3.0-3.1 mm; HL 0.55-0.58 mm; HW 0.48 mm; SL 0.63-0.65 mm; ML 1.00-1.03 mm; MTL 0.65-0.68 mm; PL 0.23-0.25 mm; CI 83-86; SI 132-137.

Head un full-face view narrow, elliptical, distinctly longer than broad, with slightly convex sides and posterior margin of head. Antennal scape long, extending beyond the posterior margin of head (SI 132-137): antennal segment II slightly shorter than III and as long as IV or more: V-VII combined as long as VIII and IX combined and almost as long as the last segment (X). Frontal carina short and thin, not extending beyond the level of posterior margin of torulus. Clypeus short, with very slightly convex anterior margin that bears 8-10 teeth. Mandible with the apical tooth large and curved, followed by 10-12 minute teeth on masticatory margin. Mesosoma elongate; in profile pronotum weakly convex dorsally; promesonotum sloping gradually to metanotal groove. Propodeum slightly lower than promesonotum with its dorsal outline almost straight in profile; propodeal junctionion angulate; declivity of propodeum widely and shallowly concave. encircled with a thin rim. Petiole large, seen in profile subrectangular, slightly longer than high and almost straight dorsally; subpetiolar process weakly developed with its ventral outline feebly convex, and anteroventral corner acutely angulate; postpetiole slightly smaller than petiole, with its node rounded above and scarcely longer than broad.

Head and antennal scape smooth and shiny. Pronotum smooth and shiny, with its anteriormost portion punctate; mesothorax and metapleuron with dense microrecticulae; propodeum extensively smooth and shiny; propodeal declivity entirely sculptured; in the area in front of the angle with fine sculpture. Petiole smooth and shiny, with its anteriormost part sparsely punctate; postpetiole also extensively smooth and shiny. Gaster, and femora and tibiae of legs smooth and shiny.

Body with relatively sparse standing hairs mixed with sparse short hairs over the surface: length of the longest pronotal hair 0.15-0.18 mm. Head, waist, gaster, antenna and legs yellow or pale brown: mesosoma dark brown.

Type Material
Holotype worker from agricultural area, new Phu Kheao W. S., Chaiyaphum Prov., NE. Thailand, 30 I 1999, W. Jaitrong leg., WJT99-AG20. Three paratype workers, same data as Holotype. Holotype and one paratype is deposited in, one paratype in , and the other in.

Etymology
The specific epithet “stenocephalus” is Latin meaning “narrow-headed”.