Aenictus itoi

Known only from the type locality in a lowland rainforest.

Identification
A member of the ceylonicus group. This species can be separated from the other members by the subpetiolar process being developed, subtriangular, with its apex spiniform and directed downward. (Jaitrong and Yamane 2013)

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

Distribution
W. Sumatra

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia.

Castes
Known only from the worker caste.

Nomenclature

 *  itoi. Aenictus itoi Jaitrong & Wiwatwitaya, 2013: 192, figs. 21A-C (w.) INDONESIA.

Worker
(Holotype and paratype workers, n = 5). TL 2.75–3.00 mm; HL 0.58–0.61 mm; HW 0.58–0.63 mm; SL 0.46–0.53 mm; ML 0.88–0.98 mm; PL 0.20–0.25 mm; CI 100–102; SI 80–88.

Head in full-face view round, almost as long as broad, sides and posterior margin convex; occipital margin bearing a carina. Antennal scape relatively short, reaching only 2/3 of head length. Frontal carina relatively short, recahing the level of posterior margin of torulus. Parafrontal ridge incomplete or almost absent. Anterior clypeal margin concave, concealed by curved anterior extension of frontal carina. Masticatory margin of mandible with a large acute apical tooth followed by a medium-sized subapical tooth, 5 denticles, and a medium-sized basal tooth; basal margin 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 relatively long, not clearly demarcated from metapleuron; metapleural gland bulla relatively small, its maximum diameter as long as distance from propodeal spiracle to metapleural gland bulla. Propodeum in profile with straight dorsal outline; propodeal junction nearly right-angled; declivity of propodeum seen from back widely and shallowly concave, encircled with a rim. Petiole almost as long as high, with its dorsal outline elevated posteriorly; subpeiolar process subtriangular, anteroventrally not angulate, its apax directed downward. Postpetiole almost as long as petiole but slightly narrower than petiole, seen in profile with its dorsal outline elevated posteriorly.

Head including antennal scape and gaster entirely smooth and shiny. Mandible very finely striate. Promesonotum smooth and shiny except for anteriormost part punctate; mesopleuron, metapleuron, lateral face of propodeum wrinkled; propodeal dorsum reticulate; petiole densely punctate; lateral face of postpetipole superficially reticulate, postpetiolar dorsum smooth and shiny.

Head and mesosoma dorsally with relatively dense standing hairs; longest pronotal hair 0.18–0.20 mm long. Head, petiole, gaster, and legs yellowish brown; mesosoma reddish brown.

Type Material
Holotype. INDONESIA: Worker from W. Sumatra, Padang, Sukarami, 1–5.I.1992, leg. F. Ito, FI92-25 (MZB). Paratypes. Four workers, same data as holotype (SKYC, THNHM).

Etymology
The specific name is dedicated to Professor Dr. Fuminori Ito of Kagawa University (Japan), who donated the type series to us.