Anochetus Mayr, 1861

Anochetus Mayr, 1861 View in CoL

( Figs 2B View Fig , 4B View Fig , 6B View Fig )

Recognition. Relatively small ants with total length measuring 3.6–3.8 mm; posterior margin of head in full-face view deeply and broadly emarginate; mandible linear and very long, apically strongly curved inwardly; petiole scale-like.

Description. Relatively small ants with total length measuring ca. 3.6–3.8 mm and head width 0.94–1.00 mm in the single Japanese species A. shohki Terayama, 1996 . Head as long as broad, broadest at level of eye, with posterior margin deeply and broadly emarginate; lateral margin behind eye shallowly concave; nuchal carina (occipital carina) running behind ‘vertex’ continuously curved, without anterior V-shaped infolding; median furrow (line) absent on vertex. Eye with rather long sparse hairs. Ocelli situated near posterior margin of head; distance between posterior ocellus and posterior margin of head about as long as distance between posterior ocelli. Mandible linear and long, inserted medially on front of cranium, apically strongly curved inwardly; in the single Japanese species apical portion with two major teeth that are arranged vertically; the lower tooth with additional smaller tooth near base. Metanotum flanked by deep anterior and posterior furrows. Opening of propodeal spiracle oval. Petiole subsquamiform, in profile view tapering apicad. Constriction between gastral segments I and II moderate; pretergite and presternite of segment II transversely striate; cinctus distinctly defined, cross-ribbed (forming series of elongate punctures). Midtibia without apical spur; hindtibia with pectinate spur only. For the structure of mesosoma, see also TERAYAMA (1996: fig. 25).

Caste differences. In A. shohki the queen differs from the worker in having the following characters: body larger (HW 0. 94–1.00 mm in the queen vs ca. 0.85 mm in the worker); eye larger (maximum diameter 0.20 mm vs. 0.13 mm); three ocelli present; meso- and metathorax with developed wings and associated structures; mesoscutellum differentiated from mesoscutum; groove dividing mesopleuron into upper and lower sections much more conspicuous than in the worker.

Remarks. The single Japanese species Anochetus shohki is confined to the Central Ryukyus (Okinawa-jima) and Southern Ryukyus, and found in semi-open sites (TERAYAMA 1996; TERAYAMA et al. 2014; HISASUE & TOKU- SHIGE 2021). The colonies are small with a single foundress. Many Asian species of Anochetus have an elongate head and an apically pointed petiole as in Odontomachus . In the Japanese species the hindwing lacks a jugal lobe, while in other species groups from Asia the jugal lobe is often present. Although in A. shohki apicoventral spurs on mid- and hindtibiae are reduced to 0 and 1, respectively, the number of spurs is highly variable in this genus ( BROWN 1978). Thelytokous parthenogenesis is known in dealate queens ( MIYAZAKI 2023).