Tetramorium cristatum

Identification
Bolton (1980) - Five species of the bicarinatum-group, as represented in the Ethiopian region, are large. These are Tetramorium gazense, Tetramorium emeryi, Tetramorium erectum, T. cristatum and Tetramorium notiale. Of these the first three are uniform brown or blackish brown in colour whilst T. notiale is uniformly orange-brown or yellowish brown with the gaster the same colour as or lighter than the alitrunk and head. Tetramorium cristatum, with its strongly contrasting dark gaster, is thus quite distinct and easy to spot. Only Tetramorium peutli in the bicarinatum-group shares the colour pattern of T. cristatum among the smaller native African species but here the postpetiole lacks a rugoreticulum dorsally and the basigastral costulae are very reduced or absent. A similar colour-scheme is present in Tetramorium bicarinatum but here the mandibles are sculptured with dense fine striae whereas they are smooth in T. cristatum and its immediate allies. The closest relatives of T. cristatum are discussed under T. gazense.

Distribution based on Regional Taxon Lists
Afrotropical Region: Guinea, Ivory Coast, Kenya, Togo, Zimbabwe.

Nomenclature

 *  cristatum. Tetramorium guineense var. cristatum Stitz, 1910: 144 (w.) TOGO. Raised to species, senior synonym of medje and material of the unavailable name ebangense referred here: Bolton, 1980: 268.
 * medje. Tetramorium guineense subsp. medje Wheeler, W.M. 1922a: 192 (w.) DEMOCRATIC REPUBLIC OF CONGO. Junior synonym of cristatum: Bolton, 1980: 268.

Worker
Bolton (1980) - TL 4.1—5.1, HL 0.94-1.20, HW 0.78-1.02, CI 81-87, SL 0.60-0.76, SI 73-81, PW 0.59-0.76, AL 1.08—1.40 (15 measured).

Mandibles smooth and shining with scattered pits. Anterior clypeal margin with a distinct median notch or impression. Clypeus with three strong longitudinal carinae, sometimes also with 1-2 more carinae which are, however, much more feeble. Sides of median portion of clypeus bounded by a narrow raised longitudinal rim or flange which is continuous with the frontal carinae over the antennal insertions; the flanges indented at about the midlength of the clypeus. Frontal carinae long and strong, reaching back almost to the occipital margin but posteriorly tending to merge into the reticular sculpture. Maximum diameter of eye 0.22-0.28, about 0.27-0.32 x HW. Propodeal spines long and strong, with a marked tendency to be slightly upcurved along their length; only rarely are they more or less straight. Metapleural lobes elongate-triangular and upcurved, acute apically. Petiole node in profile roughly rectangular in shape, the anterior and dorsal surfaces meeting in a right-angle or near right-angle and the dorsum behind this shallowly convex. Posterodorsal angle of node more acute than anterodorsal, usually sharp and slightly overhanging the feebly concave posterior face. In dorsal view the petiole showing:some variation in width, usually somewhat longer than broad but in several specimens only about as long as broad. Dorsum of head irregularly longitudinally rugose to level of eyes, often with some cross-meshes. Behind the level of the eyes the head strongly reticulate-rugose. Dorsal alitrunk reticulate-rugose and with a transverse, raised rugular crest at the promesonotal junction, the reticulum sometimes stronger in front of this ridge than behind. Petiole and postpetiole reticulate-rugose dorsally. First gastral tergite with conspicuous, fine dense basal costulae. All dorsal surfaces with numerous strong erect or suberect acute hairs. Hind tibiae with quite dense subdecumbent to decumbent short pilosity. Head, alitrunk and pedicel segments varying from bright orange-yellow to glossy orange-brown, the gaster always much darker, dark brown to blackish brown but is generally with the extreme base of the gaster (where the costulae are densest) distinctly paler.

Type Material
Bolton (1980) - Syntype workers, Togo: Bismarckburg (Conradt) [examined]. Tetramorium guineense subsp. medje. Syntype workers, ZAIRE: Medje, from stomach of toad (Lang & Chapin) [examined]. Tetramorium guinense [sic] st. cristatum var. ebangense Syntype workers, ANGOLA: Ebanga (A. Monard) [examined]. [Name unavailable.]

References based on Global Ant Biodiversity Informatics

 * Bernard F. 1953. La réserve naturelle intégrale du Mt Nimba. XI. Hyménoptères Formicidae. Mémoires de l'Institut Français d'Afrique Noire 19: 165-270.
 * 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.
 * 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
 * Stitz H. 1910. Westafrikanische Ameisen. I. Mitteilungen aus dem Zoologischen Museum in Berlin 5: 125-151.
 * Weber N. A. 1943. The ants of the Imatong Mountains, Anglo-Egyptian Sudan. Bulletin of the Museum of Comparative Zoology 93: 263-389.