Aenictus watanasiti

Judging from the known specimens of this species it is distributed from the lowland to highland (300–1100m alt.).

Identification
A member of the ceylonicus group. Jaitrong and Yamane (2013) – Aenictus watanasiti is most similar to Aenictus khaoyaiensis, but the mandible has 3 teeth (4 teeth in the latter) and the subpetiolar process is subrectangular (low, with anteroventral corner acutely angulate and ventral outline feebly convex in the latter).

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

Distribution based on Regional Taxon Lists
Oriental Region: Thailand, Vietnam.

Castes
Known only from the worker caste.

Nomenclature

 *  watanasiti. Aenictus watanasiti Jaitrong & Wiwatwitaya, 2013: 213, figs. 18A-D (w.) THAILAND.

Worker
(holotype and paratypes, n = 10). TL 2.65–3.05 mm; HL 0.53–0.65 mm; HW 0.50–0.66 mm; SL 0.38–0.50 mm; ML 0.80–1.03 mm; PL 0.20–0.26 mm; CI 96–106; SI 70–79.

Head in full-face view subrectangular, almost as long as broad, sides convex, posterior margin feebly concave. Antennal scape relatively short, slightly extending beyond 1/2 of head length. Frontal carina relatively short, not reaching the level of posterior margin of torulus. Parafrontal ridge incomplete. Anterior clypeal margin feebly concave, concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with 3 teeth, including a large apical tooth; basal margin feebly concave. Maximum width of gap between anterior clypeal margin and mandibles about 2 times as broad as maximum width of mandible. Promesonotum strongly convex dorsally and sloping gradually to metanotal groove; mesopleuron not clearly demarcated from metapleuron; metapleural gland bulla relatively large, its maximum diameter about 3.8 times as long as distance between propodeal spiracle and metapleural gland bulla. Propodeum in profile extremely lower than pronotum and relatively short with weakly convex dorsal outline; propodeal junction angulate; declivity of propodeum broadly and shallowly concave, encircled with a distinct rim. Petiole slightly longer than high, elevated posteriorly; subpetiolar process low and subrectangular, anteroventral corner acutely angulate, but posteroventral corner bluntly angulate. Postpetiole almost as long as petiole, with its dorsal outline roundly convex.

Head entirely smooth and shiny. Mandible very finely striate. Basal 1/3 of antennal scape microreticulate, apical 2/3 smooth and shiny. Promesonotum smooth and shiny except for anteriormost portion reticulate; upper portion of mesopleuron reticulate; lower portion of mesopleuron and propodeum with several longitudinal rugae; metapleuron reticulate. Petiole entirely reticulate; postpetiole reticulate except for dorsal face smooth and shiny. Legs smooth and shiny except basalmost portion of femora and tibiae micropunctate.

Head and mesosoma dorsally with relatively dense standing hairs mixed with decumbent hairs; longest pronotal hair 0.18-0.20 mm long. Head including mandible and antennal scape, mesosoma, petiole, postpetiole, and first gastral tergite dark reddish brown; tip of gaster and gastral sternites, yellowish brown.

Type Material
Holotype. THAILAND: Worker from N. Thailand, Chiang Mai Prov., Muang Dist., 7.VI.2001, leg. W. Jaitrong, WJT01-DST02 (THNHM). Paratypes. Twenty-four workers, same data as holotype (BMNH, MCZC, SKYC, THNHM) and ten workers, same colony as holotype collected by K. Eguchi, Eg01-TH-080 (SKYC, THNHM).

Etymology
The specific name is dedicated to Assoc. Prof. Suparoek Watanasit of Prince of Songkhla University, who has been a leading myrmecologist in Thailand.