Aenictus wilaiae

This species mainly inhabits lowland primary forests. W. Jaitrong observed this species preying on other ants (HKK10-06-03; Monomorium pharaonis) and termites (HKK10-06-03) in Thailand.

Identification
A member of the ceylonicus group. Jaitrong and Yamane (2013) – Aenictus wilaiae is most similar in general appearance to Aenictus pilosus. However, it is separated from the latter by the following characteristics: promesonotum in profile weakly convex (strongly convex, forming a dome in the latter); propodeum in profile with feebly convex dorsal outline (clearly straight in the latter); petiole sessile with low node, its posterior face encircled with a thin carina (not encircled with a carina in the latter); ventral margin of subpetiolar process convex (concave in the latter); postpetiole almost as long as petiole (slightly longer in the latter); body smaller.

Key to Aenictus species groups / Key to southeastern Asian Aenictus ceylonicus group species

Distribution based on Regional Taxon Lists
Oriental Region: Thailand.

Castes
Known only from the worker caste.

Nomenclature

 *  wilaiae. Aenictus wilaiae Jaitrong & Wiwatwitaya, 2013: 215, figs. 19A-C (w.) THAILAND.

Worker
(holotype and paratypes, n = 10). TL 2.10–2.55 mm; HL 0.53–0.55 mm; HW 0.50–0.53 mm; SL 0.36–0.39 mm; ML 0.75–0.83 mm; PL 0.18–0.23 mm; CI 95–100; SI 71–74.

Head in full-face view subrectangular, slightly longer than broad, sides weakly convex and posterior margin almost straight or feebly concave. Antennal scape relatively short, not reaching 2/3 of head length. Frontal carina slightly extending beyond the level of posterior margin of torulus. Parafrontal ridge absent. Anterior clypeal margin almost straight, lacking denticles and partly concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with a large acute apical tooth followed by a medium-sized sub-apical tooth, 2 denticles, and a medium-sized basal tooth; basal margin feebly concave. Maximum width of gap between anterior clypeal margin and mandibles about 1.8 times as broad as maximum width of mandible. Promesonotum convex dorsally and sloping gradually to metanotal groove; mesopleuron not clearly demarcated from metapleuron; metapleural gland bulla relatively small, its maximum diameter about 2 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile with almost straight or feebly concave dorsal outline, sloping gradually to propodeal junction; propodeal junction nearly right-angled; declivity of propodeum shallowly concave, and encircled with a distinct rim. Petiole almost as long as high, with its dorsal outline slightly elevated posteriorly; subpetiolar process generally very low, with its anteroventral corner angulate and ventral margin convex. Postpetiole almost as long as petiole, with its dorsal outline convex.

Head entirely smooth and shiny. Mandible very finely striate. Antennal scape superficially microreticulate, but shining. Promesonotal dorsum smooth and shiny except for anteriormost portion punctate, lateral face of pronotum superficially micro-reticulate and shiny; mesopleuron, metapleuron, and propodeum entirely reticulate except for metapleuron partly smooth and shiny; in addition, mesopleuron with longitudinal rugae; lateral face of propodeum with 2-3 short longitudinal rugae. Petiole and postpetiole densely punctate. Legs entirely smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs; longest pronotal hair 0.10–0.13 mm long. Head, gaster, and legs yellowish brown; mesosoma, petiole, and postpetiole reddish brown; mandible reddish brown.

Type Material
Holotype. THAILAND: Worker from E. Thailand, Chachoengsao Prov., Thatakiab Dist., 29.V.2005, leg. W. Jaitrong, WJT05-E203 (THNHM). Paratypes. Thirty-three workers, same data as holotype (BMNH, MCZC, SKYC, THNHM).

Etymology
The specific name is dedicated to the late Mrs Wilai Jaitrong, the great mother of the first author.