Ocymyrmex cavatodorsatus Prins

Bolton, B., 1981, A revision of six minor genera of Myrmicinae (Hymenoptera: Formicidae) in the Ethiopian zoogeographical region., Bulletin of the British Museum (Natural History) Entomology 43, pp. 245-307 : 266-267

Ocymyrmex cavatodorsatus Prins

Ocymyrmex cavatodorsatus Prins , 1965: 1021 figs 1, 2. Syntype workers, South Africa: Cape Prov., Dist. Upington, Louisvale, 6. viii. 1964, AcAx 3412 (A. J. Prins) (Res. Inst, for Plant Protection, Pretoria, South Africa).

I have not seen the types of this species but it is obvious from Prins' original description that cavatodorsatus is a very distinctive species. Its main diagnostic characters are as follows.

Worker. TL 4.5, HL 1.02, AL 1.41. Anterior clypeal margin without a semicircular median impression. Eyes not breaking outline of sides of head in full-face view. Alitrunk in profile characteristically shaped, with the promesonotum forming a single high, strongly arched convexity, the posterior mesonotum and anterior propodeum forming a uniform deep concavity and the remainder of the propodeum arching upwards again posteriorly before rounding narrowly into the deep and almost vertical declivity; the entire alitrunk having a strong saddle-shaped appearance in profile. Petiole node high-subconical in profile, longer than broad in dorsal view. Postpetiole broader than long in dorsal view. Base of first gastral tergite in dorsal view without a neck-like constriction, the sides of the tergite evenly convex behind the point of articulation with the postpetiole. Dorsum of head from level of eyes to occiput smooth and shining. Promesonotal arch dorsally smooth and shining, including the area between the mesothoracic spiracles. Remainder of dorsal alitrunk with faint transverse rugae which are almost effaced; the propodeal declivity smooth. Head bright red to yellowish red, the alitrunk yellowish red to brick red, the gaster distinctly darker, piceous.

As Prins points out, this species is related to barbiger in its lack of a basal gastral constriction. It is separated from barbiger by its lack of a clypeal impression, much reduced sculpture and strongly saddle-shaped alitrunk. In these aspects it seems closely related to turneri , another species without a gastral constriction, which also lacks a clypeal impression and has reduced sculpture. However, turneri has the alitrunk jet black, the clypeal margin prominent medially, the eyes large and breaking the outline of the sides of the head, the scapes with SI> 100 (apparently SI <100 in cavatodorsatus to judge by Prins' fig. 1.) and has a transverse arched crest on the alitrunk at the promesonotal junction.