Anochetus ruginotus

Identification
Zettel (2012) - TL 4.3 - 4.6 mm; Head stout, posteriorly weakly constricted, vertex deeply emarginate; longitudinal striation almost reaching nuchal carina. Eye small, with some minute setae. Mandible stout and short, MdI = 55; shaft medianly with two edges, dorsal one smooth, ventral one minutely serrate; intercalary tooth strongly developed. Pronotum with distinct longitudinal striation; propodeum with irregular rugosity. Petiole with narrow node in lateral aspect, its apex narrowly rounded when seen laterally, weakly convex (almost straight) in anterior aspect; peduncle almost absent. Gaster tergite 1 sparsely punctured. Whole dorsum with densely set, short setae, head with additional subcumbent pilosity.

Anochetus ruginotus was described from “Luzon” (Stitz 1925); the exact type locality remains unknown. A new record from northeastern Mindanao indicates a wide distribution in the archipelago. The species was set in synonymy with A. graeffei by Brown (1978). However, morphological evidence is strong that A. ruginotus is a valid species, and the two species can be easily distinguished by the characters presented in the key (couplet 5). Anochetus graeffei has a wide distribution and is also present in the Philippines. At a first glance A. ruginotus and A. graeffei have a very different habitus. While in A. graeffei the head is squared and the mesosoma is broad, A. ruginotus has a deep emargination of the vertex and the mesosoma is slender as in most other Anochetus species. Body size, ratio of PW / HW and sculpture of gaster tergite 1 (see the key) differ conspicuously when comparing Philippine specimens of the two taxa. However body size ranges are overlapping when including all populations of A. graeffei s.l. The entire mandible, but most notably its apical teeth are usually more gracile in A. graeffei than in A. ruginotus, except for the syntypes of A. rudis, which have stout mandibles, almost as A. ruginotus. An additional difference between A. ruginotus and A. graeffei is found in head sculpture. Although strong variation is observed in the extension of the striation in A. graeffei, in all forms a strong puncturation is intermitting the striae, so that in densely sculptured specimens the intervals appear interrupted. In contrast setiferous punctures in A. ruginotus are very fine and hardly “disturbing” a regular striation. A difference in the apex of the petiolar node, which is rounded in A. ruginotus and incised in some Philippine A. graeffei specimens, is not consistent in A. graeffei s.l.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Philippines.

Nomenclature

 *  ruginotus. Anochetus ruginotus Stitz, 1925: 114 (w.) PHILIPPINES. Junior synonym of graeffei: Brown, 1978c: 557. Revived from synonymy: Zettel, 2012: 164.

Worker
Zettel (2012) - Holotype: TL 4.58; HL 1.20; HW 1.05; CI 88; MdL 0.69; MdI 58; SL 0.96; SI 91; MsL 1.38; PnW 0.56; PtH 0.44; PtL 0.45; PtW 0.24.