Technomyrmex gibbosus

Widely distributed in Japan (Imai, Kihara, Kondoh, et al., 2003), T. gibbosus nests in dead twigs and dead bamboo stems. Nuptial flights take place on September. (Japanese Ant Image Database)

Identification
Bolton (2007) - A member of the Technomyrmex gibbosus group. Its closest relative appears to be Technomyrmex vexatus, the current known distribution of which is restricted to Morocco. The two are easily separated as in gibbosus the eyes are larger and located distinctly farther forward on the head capsule than in vexatus (OI 22 - 25, EPI 68 - 76); also the posterior margin of the head in vexatus is shallowly impressed in full-face view, without a median indentation such as occurs in gibbosus. Finely microreticulate sculpture is well developed and conspicuous on the dorsal head of gibbosus, but in vexatus this cephalic sculpture is semi-effaced, very weak and superficial.

These two species are separated by an enormous distance and it is interesting to speculate if they shared an immediate common ancestor, or if they are the remnants of a fairly distinctive species group that once extended across the width of the southern Palaearctic, or if their shared characters have been acquired convergently.

Distribution
This species is distributed from Hokkaido to Kyushu, but very rare in Hokkaido (known from one record only) (Onoyama, 1989).

This species has been recorded from North Korea (Radchenko, 2005) but to the best of my knowledge has not yet been found in China, where its presence should be expected (Bolton 2007).

Distribution based on Regional Taxon Lists
Indo-Australian Region: Malaysia. Palaearctic Region: Democratic Peoples Republic of Korea, Japan, Republic of Korea.

Nomenclature

 *  gibbosus. Technomyrmex gibbosus Wheeler, W.M. 1906c: 319, pl. 41, fig. 4 (w.) JAPAN. Wheeler, G.C. & Wheeler, J. 1951: 205 (l.). See also: Bolton, 2007a: 81.

Description
Bolton (2007) - TL 2.4 - 3.0, HL 0.63 - 0.68, HW 0.54 - 0.61, SL 0.50 - 0.54, PW 0.38 - 0.42, WL 0.76 - 0.84 (10 measured). Indices: CI 86 - 91, SI 85 - 93, OI 27 - 29 EPI 50 - 58, DTI 124 - 130.

Dorsum of head behind clypeus entirely lacks setae. Anterior clypeal margin with an insignificant median indentation in the apron. In full-face view the posterior margin of the head with a median indentation and the sides shallowly convex. Eyes of moderate size. located well in front of the midlength and their outer margins usually just break the outline of the sides in full-face view. Dorsum of mesosoma, and declivity of propodeum, entirely lack setae. With mesosoma in profile the mesonotal dorsal outline convex, consisting of a shallowly convex anterior section that curves broadly and evenly into a more sloping shallow convexity that descends to the metanotal groove. Propodeum in profile with a short convex dorsal surface that rounds into the declivity; the two surfaces not separated by a sharp angle. Gastral tergites 1 - 3 without setae; gastral tergite 4 with 1 - 2 pairs present. Scapes and tibiae without setae. Head and mesosoma medium to dark brown, often with a reddish tint; gaster about the same colour to dark brown. Legs dull yellow to yellowish brown.

Type Material
Bolton (2007) - Syntype workers, Japan: Yamanaka (Suruga), 1100 ft, 22.iii.l905, no. 2951 (H Sauter) [examined]. 16 worker syntypes of gibbosus are mounted on three pins. Two of these pins hold 15 of the workers (on three cards) and they bear only the data: Japan (N Sauter). The third pin has only one specimen but carries the fuller data recorded above.

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