Aenictus nesiotis

This widespread species occurs in the Philippines, Papua New Guinea and Australia.

Identification
A member of the pachycerus group. Head capsule completely punctate; pronotum entirely sculptured with dense micro-reticulations. This species is most similar to A. aratus, but differs in the narrower head (cephalic index < 88 and head width < 0.70mm compared to cephalic index > 87 and head width > 0.70mm in A. aratus) and the longer scapes (scape index > 107 compared to < 103 in A. aratus).

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



Distribution based on Regional Taxon Lists
Australasian Region: Australia. Indo-Australian Region: New Guinea, Philippines.

Biology
The type material consists of specimens taken from three colonies (Wheeler and Chapman 1930). One was found with numerous larvae and was nesting in a brush-pile; another, also with brood, was occupying earthworm burrows.

Castes
Known only from the worker caste.

Nomenclature

 *  nesiotis. Aenictus (Aenictus) aratus subsp. nesiotis Wheeler, W.M. & Chapman, in Wheeler, W.M. 1930g: 208, fig. 7 (w.) PHILIPPINES. Junior synonym of aratus: Wilson, 1964a: 446. Revived from synonymy and raised to species: Shattuck, 2008c: 11.

The non-Australian material of this species shows only minor differences from Australian populations, none of which suggest separate species are involved. These differences include a slightly broader anterior petiolar face and less distinct sculpturing in Philippines specimens (especially those from Palawan) compared to most PNG/Australian specimens. However, both of these characters show considerable variation with essentially all morphologies found in both regions. Because of this all specimens are considered to belong to a single wide-ranging species.

The larva described by Wheeler and Wheeler (1984) under the name A. aratus originated from the Philippines and had previously been identified as “A. a. nesiotus var. fraterculus” (an unavailable infrasubspecific name associated with A. aratus by Wilson, 1964). It is likely this larva belongs to A. nesiotus rather than A. aratus as A. aratus is not known to occur in the Philippines.

Description
Mandible triangular with numerous small teeth, those along the medial region of the masticatory margin ill defined; anterior clypeal border broadly convex, extending slightly anterior of frontal lobes; parafrontal ridges well developed, extending posteriorly approximately 1/3 length of head capsule; subpetiolar process broadly convex anteriorly, flat posteriorly; head entirely punctate; mesosoma uniformly punctate, generally with weak, ill-defined longitudinal rugae on dorsum of pronotum and lateral surfaces posterior of pronotum; body brown to black, anterior section of head sometimes lighter, distal antennae and legs always lighter.

Measurements. Worker (n = 15) - CI 82–88; HL 0.75–0.84; HW 0.64–0.70; MTL 0.67–0.79; ML 1.11–1.24; SI 107–115; SL 0.70–0.78.

Type material
Numerous specimens from three colonies found at Dumaguete. One of these, with numerous larvre was nesting in a brush-pile; another, also with brood, was occupying earthworm burrows.