Anochetus isolatus

This is a wide ranging species known from the Philippines south to the Solomon Islands and westward to the tip of Cape York Peninsula, Queensland. It is one of only two Australian Anochetus species which also occurs outside Australia. It is found in rainforest where it nests in rotten wood.

Identification
The distinctive shape of the petiolar node, being drawn dorsally into a narrow, blunt point, will separate this species from all others in Australia. Additionally, the pronotum is relatively narrower and the eye relatively smaller than in most other Australian species.

Identification Keys including this Taxon

 * Key to the Anochetus Species of Asia, Melanesia and the Pacific Region
 * Key to Australian Anochetus Species

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

Nomenclature

 *  isolatus. Anochetus cato subsp. isolatus Mann, 1919: 302, fig. 11 (w.m.) SOLOMON IS. Raised to species: Wilson, 1959a: 508. Senior synonym of rossi, splendens: Brown, 1978c: 557 (see also p. 585). See also: Shattuck & Slipinska, 2012: 13.
 * splendens. Anochetus splendens Karavaiev, 1925c: 289, fig. 11 (q.) INDONESIA (Aru I.). Junior synonym of isolatus: Brown, 1978c: 557.
 * rossi. Anochetus rossi Donisthorpe, 1949c: 747 (w.q.) NEW GUINEA. [Unresolved junior primary homonym of rossi Donisthorpe, above.] Junior synonym of isolatus: Brown, 1978c: 557.

Taxonomic Notes
The concept of this species adopted by Shattuck & Slipinska (2012) follows that developed by Brown (1978), noting that Brown left many questions concerning the taxonomy of this species and close relatives unanswered. The specific specimens examined match each other very closely in sculpturing and show minimal variation in colour. However, a wide range of additional material is present in ANIC which varies from this pattern in the development of sculpturing and colour, most of which was outlined by Brown (1978). The true status of this and related species will require a detailed study of this additional material.

Description
Worker description. Sculpturing on front of head extending slightly beyond eyes. Scapes just reaching posterolateral corners ('lobes') of head; lacking or with a few short, inclined erect hairs. Pronotum and mesonotum smooth and shining. Dorsal surface of propodeum with transverse striations which extend laterally to the level of the spiracle and propodeal lobe. Propodeal angles rounded. Metanotal groove with coarse striations. Petiolar node drawn dorsally into a narrow point, lacking sculpture. Erect hairs on hind tibiae short, scattered and inclined. Colour dark brown, petiole, gaster and legs yellow to yellow-red, antennae, mandibles and posterior corners of head slightly lighter in colour than remainder of head capsule.

Measurements. Worker (n = 5): CI 86–90; EI 12–15; EL 0.15–0.20; HL 1.39–1.72; HW 1.25–1.49; HFL 1.14–1.38; ML 1.68–1.99; MandL 0.76–0.93; MTL 0.82–1.04; PronI 53–55; PronW 0.68–0.80; SL 1.09–1.29; SI 87–91.