Aenictus itoi, Jaitrong & Yamane, 2013

Jaitrong, Weeyawat & Yamane, Seiki, 2013, The Aenictus ceylonicus species group (Hymenoptera, Formicidae, Aenictinae) from Southeast Asia, Journal of Hymenoptera Research 31, pp. 165-233 : 191-192

Aenictus itoi sp. n. Fig. 21A-C

Type material examined.

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).

Non-type material examined.

W. Sumatra, Padang, Sukarami, 22.VIII.1996, leg. F. Ito (SKYC).

Worker measurements

(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.

Description of worker

(holotype and paratypes). 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.

Etymology.

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

Distribution.

W. Sumatra ( Fig. 26B ).

Bionomics.

So far this species has been known only from the type locality in a lowland rainforest.

Remarks.

This species can be separated from the other members by the subpetiolar process being developed, subtriangular, with its apex spiniform and directed downward.

Figures

Figure 21. Aenictus itoi (specimen from Sumatra). A Head in full-face view B body in dorsal view C body in profile.

Figure 26. Distribution of Aenictus ceylonicus group. A Aenictus baliensis, Aenictus gonioccipus, Aenictus longicephalus, Aenictus minipetiolus, Aenictus pilosus B Aenictus appressipilosus, Aenictus cylindripetiolus, Aenictus itoi, Aenictus jawadwipa, Aenictus sundalandensis.