Tetramorium dysderke

Identification
This small species is remarkable in that it occupies a position halfway between the shilohense-complex (Tetramorium intonsum, Tetramorium jugatum, Tetramorium shilohense, Tetramorium termitobium) and the subcoecum-complex (Tetramorium amaurum, Tetramorium subcoecum, Tetramorium traegaordhi, Tetramorium typhlops, Tetramorium warreni), its main characters being a patchwork of those predominating in the two complexes. In particular, it retains the distinct sculpture and relatively long scapes seen in T. shilohense and its allies but has the minute eyes and very short frontal carinae characteristic of the subcoecum-complex. This strange combination of characters will quickly isolate T. dysderke from all other members of the group as the presence of very short frontal carinae and eyes of a single ommatidium, coupled with dense and conspicuous sculpture on the head and alitrunk and an SI of 80, is restricted to this species.

Distribution based on Regional Taxon Lists
Afrotropical Region: Nigeria.

Nomenclature

 *  dysderke. Tetramorium dysderke Bolton, 1980: 287 (w.) NIGERIA.

Worker
Holotype. TL 2.4, HL 0.59, HW 0.50, CI 85, SL 0.40, SI 80, PW 0.34, AL 0.64.

Mandibles longitudinally striate. Anterior clypeal margin entire, without notch or impression, the median carina running the length of the clypeus. Frontal carinae very short and very feebly developed, no stronger than the other cephalic sculpture, diverging from the frontal lobes and ending at the level of the eyes; inconspicuous. Antennal scrobes absent. Eyes minute, consisting of only a single ommatidium on each side, its diameter approximately 0.03, about 0.06 x HW. Propodeum armed with a pair of short triangular spines; the metapleural lobes triangular and only slightly shorter than the spines. Petiole node low and short-rectangular in profile, with a roughly right-angular anterodorsal angle and a rounded Posterodorsal angle. In dorsal view the petiole node is about as long as broad. Dorsum of head finely but distinctly irregularly longitudinally rugulose, the spaces between the rugulae finely punctulate. Dorsal alitrunk with a low transverse ridge on the anterior pronotum; behind this the promesonotum finely longitudinally rugulose with punctulate interspaces. Dorsal surfaces of petiole and postpetiole unsculptured but the former with a fine transverse crest running across the anterior face. First gastral tergite unsculptured and shining. All dorsal surfaces of head and body with numerous short, fine, standing hairs. Dorsal (outer) surfaces of middle and hind tibiae only with short, fine pubescence which is decumbent or appressed. Colour uniform yellow.

Type Material
Holotype worker, Nigeria: Gambari, 24.vii.1969, in rotten stump, C.R.I.N. Exp. Sta. (B. Bolton).

References based on Global Ant Biodiversity Informatics

 * Bolton B. 1980. The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Ethiopian zoogeographical region. Bulletin of the British Museum (Natural History). Entomology 40: 193-384.