Tetramorium diomandei

Identification
Bolton (1980) - The two species T. diomandei and Tetramorium somniculosum form a close pair within the shilohense-group, characterized by their bizarre pilosity, the highly irregular outline shape of their dorsal alitrunk, and the presence of a strongly raised transverse crest on the anterior part of the pronotum. Coupled with this they have strongly developed frontal carinae and sculpture which is generally coarser than is seen elsewhere in the group. Differences between the two species are tabulated as follows.

T. diomandei
 * Flattened hairs of first gastral tergite scale-like or leaf-like, pubescence between them minute and inconspicuous.
 * Dorsum of head with 3-5 longitudinal carinae between the frontal carinae.
 * Dorsal outline of alitrunk highly irregular.
 * Scapes short, SI 70-74.
 * Petiole in dorsal view slightly broader than long.
 * Raised flanges of frontal carinae thick and coarse.
 * Median clypeal carina not reaching anterior clypeal margin.

T. somniculosum
 * Flattened hairs of first gastral tergite long and spatulate, pubescence between them conspicuous and as long as the flattened hairs.
 * Dorsum of head with 9-12 longitudinal carinae between the frontal carinae.
 * Dorsal outline of alitrunk not so strongly irregular.
 * Scapes longer, SI 75-81.
 * Petiole in dorsal view longer than broad.
 * Raised flanges of frontal carinae narrow and fine.
 * Median clypeal carina usually reaching anterior clypeal margin (rarely broken or interrupted).

Distribution based on Regional Taxon Lists
Afrotropical Region: Cameroon, Ivory Coast.

Nomenclature

 *  diomandei. Tetramorium diomandei Bolton, 1980: 268, figs. 67, 71, 73 (w.) IVORY COAST.

Worker
Holotype: TL 3.2, HL 0.83, HW 0.78, CI 94, SL 0.56, SI 72, PW 0.52, AL 0.90. Paratypes: TL 3.1—3.5, HL 0.78-0.86, HW 0.74-0.80, CI 91-95, SL 0.52-0.57, SI 70-74, PW 0.48-0.56, AL 0.84-0.94 (25 measured). As holotype but maximum diameter of eye 0.08-0.10, about 0.10-0.13 x HW; with 4 or 5 ommatidia in the greatest diameter.

Mandibles longitudinally striate. Anterior clypeal margin with a broad but quite shallow median impression, the portion of the clypeus behind this impression shallowly transversely concave between a pair of longitudinal carinae. The transversely concave anterior portion of the clypeus virtually unsculptured but the posterior portion rugulose between the lobes of the frontal carinae. Frontal carinae long and strongly developed, sinuate along their length, reaching back almost to the occipital margin and surmounted by a thick, coarse rim or crest. Antennal scrobes broad but shallow. Eyes very small, with four ommatidia across the greatest diameter. Maximum diameter of eye 0.08, about 0.10 x HW, less than the maximum diameter of the scape. Dorsal outline of alitrunk in profile very irregular (Fig. 73), folded into a number of prominences and depressions. Anterior portion of pronotum (just behind the cervical shield) bounded by a very strong transverse crest which runs from the anterolateral pronotal angle up the sides of the pronotum and across the dorsum. Propodeum armed with a pair of extremely stout, broad spines; the metapleuron — with a pair of shorter but very broad-based triangular lobes. Petiole in profile with an elongate thick peduncle and a small, roughly rectangular node. In dorsal view the petiole node is very slightly broader than long. Dorsum of head sculptured with three very strong, coarse carinae between the frontal carinae. Spaces between the carinae with finer, blunt rugosity, the tops of the carinae and the larger rugae dull and with a finely beaded appearance due to the presence of minute dense punctulation. Dorsal alitrunk coarsely rugose, predominantly longitudinally so but with scattered transverse elements. Dorsal surfaces of petiole and postpetiole finely reticulate-rugulose, the base of the first gastral tergite finely feebly shagreened. Dorsal surfaces of head, alitrunk and pedicel segments without standing hairs of any description; with bizarre thick, minute, stud-like or scale-like hairs thinly distributed over the surfaces, most easily visible on head and postpetiole. First gastral tergite with numerous subdecumbent to decumbent flattened scale-like or leaf-like hairs. Spaces between these bizarre hairs with very sparse, minute, appressed pubescent hairs which are scarcely visible. Tibiae of middle and hind legs only with short, appressed pubescence. Colour uniform brown, the appendages lighter.

Paratypes: Sculpture somewhat variable. In some specimens the dorsum of the head having 3-5 coarse carinae between the frontal carinae and the posterior half of the clypeus often with a well-defined fine median carina. Basic brown colour of the body with a dull reddish tint in some individuals.

Type Material
Holotype worker, Ivory Coast: Tai Forest, 23.viii.1975, no. 1 (T. Diomande). Paratypes. 42 workers with same data as holotype (BMNH; ; ).

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.