Aenictus chapmani

The type series was obtained from "several scattered files of workers were found crossing a native trail in second-growth forest during the early part of the night."

Identification
A member of the pachycerus group.

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

Distribution
Known from the Huon Peninsula, NE New Guinea and Duamagete, Philippines.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Borneo, New Guinea.

Castes
Known only from the worker caste.

Nomenclature

 *  chapmani. Aenictus chapmani Wilson, 1964a: 456, figs. 45, 46 (w.) NEW GUINEA.

Worker
Holotype : HW 0.72 mm, HL 0.76 mm, SL 0.70 mm. Antenna 10-segmented. Mandible somewhat narrower with reference to the head than in the "typical" form (e. g., in laeviceps and pachycerus), its maximum width 0.16 mm; indistinctly 3-toothed. In closure the mandibles leave a gap between their posterior margins and the clypeus of about 0.02 mm. Anterior clypeal border very feebly concave, unarmed. Parafrontal ridge 0.10 mm long, in side view prosalient as a narrow, irregular lobe. Occiput almost perfectly straight, lacking a collar. Posterior surface of petiolar node drawn into a low, obtuse angle. Main portion of subpetiolar process large, lobose, anteriorly directed; surmounted by a thin, acute flange which is posteriorly directed. Pilosity abundant; pronotal hairs up to 0.20 mm in length.

Head shining. Mesosoma almost entirely microreticulate (reticular diameter 0.01 mm) and opaque. Microreticulum on mesonotum weakly developed, the surface only subopaque. In addition the meso-, metathorax, and propodeum bear about 25 longitudinal rugae. Pedicel wholly microreticulate and opaque. Head, alitrunk, and pedicel rich medium reddish brown; gaster and appendages a contrasting light reddish brown.

Paratypes: 7 workers from same nest series show little deviation from holotype. HW 0.70-0.77 mm. One paratype chosen at random: HW 0.73 mm, HL 0.76 mm, SL 0.71 mm. Mandibles range from distinctly 3-toothed to distinctly 4-toothed, with intermediate development of the 4th tooth as 1 or 2 denticles between the preapical basal teeth.

Type Material
Zingzingu, 1200 m, Mongi Watershed, Huon Peninsula, NE New Guinea.

Etymology
This species is named for the late Dr J. W. Chapman, in recognition of his pioneering taxonomic and ecological studies of Philippine army ants.