Anochetus risii

Identification
Brown (1978) – Ferruginous yellow in color, with pale yellow legs; the pronotum is striate or rugulose in front and around the sides of the disc, but the center of the disc is smooth and shining. In A. risii and related species, the dorsal inner margin of the mandible is nearly straight and is edentate with a smooth margin, the preapical angle tends to be acute and is directed somewhat apicad as well as mesad, and the intercalary tooth of the apical trio is reduced and situated far out on the ventral apical tooth near its apex, which may thus appear furcate in young specimens. In older specimens, the intercalary tooth may be worn to a nub, or broken off, and scarcely detectable. A representative worker from Kusang, China has HL 1.62, HW 1.44, ML 1.19, scape L 1.58, eye L 0.28 mm; CI 89, MI 73.

Distribution based on Regional Taxon Lists
Indo-Australian Region: Indonesia. Oriental Region: Taiwan, Vietnam. Palaearctic Region: China.

Nomenclature

 *  risii. Anochetus risii Forel, 1900c: 60 (w.) CHINA (Hong Kong).
 * Wheeler, W.M. 1927h: 84 (m.); Wheeler, W.M. 1928c: 8 (q.).
 * Senior synonym of taiwaniensis: Chen, Yang & Zhou, 2019: 64.
 * taiwaniensis. Anochetus taiwaniensis Terayama, 1989a: 26, figs. 1-6 (w.) TAIWAN.
 * Junior synonym of risii: Chen, Yang & Zhou, 2019: 64.

Worker
Chen et al. (2019) - TL 5.12–5.34, HL 1.67–1.69, HW 1.44–1.46, CI 85–87, SL 1.55– 1.57, SI 106–108, ED 0.11–0.12, PW 0.80–0.82, MSL 2.33–2.36, PL 0.37–0.39, PH 0.74–0.76, DPW 0.30–0.32, LPI 202–207, DPI 83–85 (n = 5).

In full-face view head longer than broad, posterior margin strongly concave. Mandibles linear, gradually broadened apically; inner margin with several denticles, gradually decreasing in size towards base; apical portion with three distinct teeth. Antennae 12-segmented; scapes surpassing to posterior corners of head by about 1/5 of its length. Eyes large, maximum diameter of eye wider than the basal width of mandibles. In lateral view mesosoma slender. Pronotum weakly convex. Promesonotal suture shallowly impressed. Mesonotum weakly convex, sloping posteriorly. Metanotal groove deeply concave. Dorsum of propodeum almost straight, posterodorsal corner bluntly angled. Petiole cone-shaped and slightly inclined posteriorly, with a pointed dorsal apex, anterior margin weakly convex, posterior margin almost straight; subpetiolar process triangular, directed posteroventrally.

Frons longitudinally to obliquely striate posteriorly; frontal lobes and clypeus weakly striate, remainder of head smooth and shining. Mesosoma smooth and shining, propodeum and lower part of metapleuron obliquely rugose. Sometimes sides of pronotum weakly longitudinal rugose. Petiole smooth and shining, basal area weakly striate. Gaster smooth and shining. Body dorsum with abundant erect to suberect hairs and dense decumbent pubescence; scapes and tibiae with scattered suberect hairs and dense decumbent pubescence. Body blackish brown; antennae and legs yellowish brown.