Tetramorium gazense

Identification
Bolton (1980) - Of the five large species of this group which occur in the Ethiopian region two, Tetramorium emeryi and Tetramorium erectum, are characterized by the shape of the petiole node and are easily separated (see above under T. emeryi, T. erectum). The remaining three form a very close triad of species which are separated by their colour or colour pattern. These are Tetramorium cristatum, T. gazense and Tetramorium notiale. However, in the case of these three species the colours appear to be discrete, there are no known intermediates, and the colours seem very stable over the extensive ranges of the species involved. Although it remains a truism that colour is to be treated with caution in the genus Tetramorium, it seems as if the species of the bicarinatum-group have developed very stable colour-patterns, as is witnessed in Tetramorium bicarinatum itself and in Tetramorium insolens (see Bolton, 1977; 1979) and other members of the group from outside the Ethiopian region. In view of this I am treating these three names as distinct species, at least until intermediates can be found to refute the decision. Thus, of the three T. gazense is uniform dark brown or blackish brown; T. notiale is uniform bright orange-brown or yellow-brown, usually with the gaster lighter than the head and alitrunk; T. cristatum is bright orange-yellow to bright orange-brown with the gaster always much darker, very dark brown or blackish brown.

Distribution based on Regional Taxon Lists
Afrotropical Region: Kenya, Zimbabwe.

Nomenclature

 *  gazense. Tetramorium guineense subsp. gazensis Arnold, 1958: 122, fig. 3 (w.) ZIMBABWE. Raised to species: Bolton, 1980: 270.

Worker
Bolton (1980) - TL 4.1-4.9, HL 1.00-1.20, HW 0.86-1.04, CI 85-87, SL 0.66-0.76, SI 71-76, PW 0.60-0.74, AL 1.14-1.30 (10 measured). Mandibles smooth and shining with scattered pits. Anterior clypeal margin with a distinct median notch or impression. Clypeus with three major longitudinal carinae, also commonly with one or more extra, more — feeble rugulae. Sides of median portion of clypeus strongly marginate, the raised rim forming the margin running into the clypeal apron anteriorly and continuous with the frontal carinae posteriorly. Frontal carinae strong, extending back almost to the occipital margin where they merge with the rugoreticulum. Eyes of moderate size, maximum diameter 0.24-0.28, about 0.25-0.28 x HW. Propodeal spines long and usually stout, acute apically and upcurved along their length. Metapleural lobes elongate-triangular, often spiniform apically, upcurved. Petiole with the node roughly rectangular, the anterior face vertical or very feebly concave, the dorsum shallowly convex and the posterior face slightly concave. The antero- and posterodorsal angles either both making roughly a right-angle where they meet the dorsum or the — anterior angle somewhat blunter than the posterior. In dorsal view the nodes slightly longer than broad, sometimes about as broad as long but always broader behind than in front. Dorsum of head longitudinally rugose to level of posterior margins of eyes, behind which the head has a coarse rugoreticulum. Dorsal alitrunk strongly reticulate-rugose; in some individuals this may be weaker on the mesonotum. Alitrunk with a transverse crest at the promesonotal junction. Dorsal surfaces of both petiole and postpetiole coarsely reticulate-rugulose. Base of first tergite with fine dense costulation. All dorsal surfaces of head and body with numerous strong erect or suberect hairs. Colour uniform dark brown, sometimes blackish brown.

Type Material
Bolton (1980) - Syntype workers, RHODESIA: Melsetter, xii. 1948, 5000 ft [1520 m] (G. Arnold) [examined].

References based on Global Ant Biodiversity Informatics

 * Garcia F.H., Wiesel E. and Fischer G. 2013.The Ants of Kenya (Hymenoptera: Formicidae)Faunal Overview, First Species Checklist, Bibliography, Accounts for All Genera, and Discussion on Taxonomy and Zoogeography. Journal of East African Natural History, 101(2): 127-222
 * IZIKO South Africa Museum Collection