Tetramorium tychadion

Identification
Bolton (1980) - Of the species of the lucayanum-complex, characterized by having the pedicel segments distinctly sculptured and the mandibles (usually) markedly striate, the species Tetramorium amissum and T. tychadion are distinguished by possessing suberect pubescence on the hind tibiae. In the other members of the complex Tetramorium lucayanum and Tetramorium versiculum), and in all other members of the camerunense-group, such pubescence is absent. The differences separating T. tychadion from T. amissum are tabulated under the latter name.

Distribution based on Regional Taxon Lists
Afrotropical Region: United Republic of Tanzania.

Nomenclature

 *  tychadion. Tetramorium tychadion Bolton, 1980: 342 (w.) TANZANIA.

Worker
Holotype worker. TL 3.6, HL 0.84, HW 0.76, CI 90, SL 0.64, SI 84, PW 0.54, AL 0.96.

Mandibles sharply but finely longitudinally striate. Anterior clypeal margin with a small median notch. Clypeus with a sharp median carina, otherwise unsculptured on the central portion except for a pair of weaker carinae which flank the median. Frontal carinae running back beyond the level of the posterior margins of the eyes then rapidly fading out, not continued to the occipital margin like the trong rugae which run between them. Eyes of moderate size, maximum diameter 0.18, about 0.24 x HW and with 8 ommatidia in the longest row. Metanotal groove forming a very shallow impression in the dorsal alitrunk in profile. Propodeal spines long, strong and acute, straight and rapidly tapering along their length in profile. Metapleural lobes shorter, about half the length of the spines, roughly triangular and feebly upcurved. Petiole node in profile higher than long, the dorsal length less than the height of the tergal portion, and with a conspicuous oblique rugula or irregular carina which runs diagonally from the anterodorsal corner of the node to the posteroventral junction with the postpetiole. The area of the side of the node in front of this rugula unsculptured, behind it sculptured. Petiole node in dorsal view longer than broad and the diagonal rugula of the sides seen to be continuous across the anterior face as a narrow rim or crest. Dorsum of head with sharp, widely spaced strong rugae running from posterior clypeal margin to occiput; about 9-10 such rugae present between the frontal carinae at eye level. Occipital region with one or two anastomoses but without a rugoreticulum. Ground-sculpture an almost effaced granulation, the surfaces between the rugae glossy and mostly smooth. Dorsal alitrunk rugose, the components finer than those on the head, longitudinal on the pronotum but irregular or with cross-meshes elsewhere. Dorsal surfaces of petiole and postpetiole with spaced-out fine rugulae, the spaces between them shining. First gastral tergite unsculptured. All dorsal surfaces of head and body with numerous long, stout, standing hairs which are acute apically. The longest hairs on the alitrunk distinctly exceeding the maximum diameter of the eye. Dorsal (outer) surfaces of hind tibiae with fine suberect to subdecumbent pubescence but without stout hairs such as are seen elsewhere on the body. Colour uniform dark brown, the legs somewhat lighter.

Type Material
Holotype worker, Tanzania: Korogwe, vi.1959 (O.R.).