Aenictus dentatus

According to Annette et al. (2003) in Pasoh, Malay Peninsula, Aenictus dentatus foraged on the forest floor in the day and night and preyed on ants of the genus Pheidole. We found this species preying on the ants of the genus Nylanderia in Lambir National Park, Sarawak (SR04-SKY-11). This species occurs from the sea level to highlands (up to 1,300 m a.s.l., Bodong Jaya, southern Sumatra) and inhabits primary and disturbed forests. (Jaitrong, Yamane and Wattanachai 2012)

Identification
A member of the pachycerus group. Jaitrong, Yamane and Wattanachai (2012) - In several characters variation is found that may or may not be of geographic nature. The subpetiolar process varies from low (its ventral outline weakly convex as seen in the Sumatran population and some colonies collected from Borneo such as Eg96-BOR-475, SB96-SKY-26 and SR04-SKY-11) to subtriangular (apex directed down-ward as seen in the type series and some colonies collected from Borneo such as Eg96-BOR-324 and Eg-BOR-545, and the single colony collected by Sk. Yamane from East Kalimantan). Size variation occurs between populations; the specimens from Sumatra are slightly larger than the type series (HW 0.80 - 0.85 mm vs. 0.72 - 0.78 mm). Within the Bornean population the variation in head width is greater: 0.75 mm to 0.88 mm. The specimens collected from Borneo tend to be darker in coloration than the lectotype and the other specimens from Malay Peninsula. However, in most of the characters the specimens from all parts of Sundaland agree with the type series, except for the single colony collected from West Java (FI95-676, SKYC and THNHM), in which the propodeal junction is simply right-angled, in profile not forming a overhanging tooth.

Aenictus paradentatus and Aenictus dentatus are very similar in general appearance as they share the distinctive coarse sculpture on head and mesosoma, and the relatively long antennal scape, extending beyond the posterior margin of the head. However, they differ in several significant characters. The antennal scape is relatively shorter in A. paradentatus (SI 117 - 124) than in A. dentatus (SI 143-152). No overlap is observed in HW / SL between the species. The posterior portion of the head in full-face view is relatively broader in A. paradentatus than in A. dentatus. The first gastral tergite is weakly shagreened with smooth interspaces in the former, while it is wholly smooth and shiny in the latter. The petiole has no peduncle in the former, but has a short but distinct peduncle in the latter.

Key to Aenictus species groups / Key to Aenictus pachyerus group species

Distribution
India, Malaysia and Borneo.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, Malaysia. Oriental Region: India, Thailand, Vietnam. Palaearctic Region: China.

Castes
Known only from the worker caste.

Nomenclature

 *  dentatus. Aenictus aitkeni var. dentata Forel, 1911d: 383 (w.) WEST MALAYSIA. Raised to species: Wilson, 1964a: 460. See also: Jaitrong, Yamane & Tasen, 2012: 134.

Worker
Wilson (1964) - Kuching: HW 0.76 mm, HL 0.92 mm, SL 1.09 mm. Other workers in this series have HW 0.78-0.81 mm. Bombay: HW 0.87 mm, HL L03 mm, SL 1.09 mm. Other workers in this series have HW 0.87-0.88 mm. Antenna 10-segmented. Mandibles typical. Clypeus convex, entire, unarmed. Parafrontal ridge prominent, about 0.5 mm long; prosalient and acutely angular in side view. Occiput convex, with a large, well demarcated collar. Propodeal junction developed into a high, thin transverse ridge which in side view appears as a large, acute "tooth" overhanging the declivitous face. Subpetiolar process a low, irregularly shaped lobe directed downward. Pilosity abundant and long; hairs on pronotum as long as 0.30 mm.

Head, mesosoma, and pedicel entirely microreticulate (reticular diameters about 0.01 mm) and opaque in Kuching series; in the Bombay series, a small area on the gena is feebly shining. In addition, lateral mesosomal surface bearing several longitudinal rugae, 5-6 in the Kuching series and about 10 in the Bombay series. Medium reddish brown overall, except for occiput, which is a somewhat contrasting dark reddish brown.