Tetramorium versiculum

Bolton collected the type material, finding this ant in the litter and a rotten log. Additional specimens were found by Gomez in the soil of a fragmented forest and by Taylor et al. (2018) in pitfall traps in Benin.

Identification
Bolton (1980) - A member of the  Tetramorium lucayanum species complex in the Tetramorium camerunese  species group. Very closely related to Tetramorium lucayanum and sharing the delicate to indistinct mandibular sculpture and coarse petiolar sculpture of that species. The overall construction of the petiole is also the same in both species. However, T. versiculum is a much more densely and coarsely sculptured species than T. lucayanum and the following differences distinguish the two. In T. lucayanum the postpetiole is mostly smooth, with a few weak longitudinal rugulae, whereas in T. versiculum the postpetiole is sharply and densely costulate or sulcate, with very little space between the components. Ground-sculpture on the head is virtually absent in T. lucayanum so that the spaces between the rugulae are smooth, but in T. versiculum a conspicuous punctulate or granular ground-sculpture is present. Although both species have about the same number of longitudinal rugulae on the head those in T. lucayanum are fine and quite sharp whilst those in T. versiculum are broader and coarser. This, coupled with the presence of ground-sculpture in T. versiculum makes its head look much more strongly sculptured.

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

Nomenclature

 *  versiculum. Tetramorium versiculum Bolton, 1980: 343 (w.) GHANA.

Worker
Holotype. TL 3.4, HL 0.86, HW 0.76, CI 88, SL 0.64, SI 84, PW 0.54, AL 0.96. Paratypes (30 measured): TL 3.1-3.3, HL 0.76-0.84, HW 0.68-0.74, CI 87-90, SL 0.58-0.62, SI 83-88, PW. 0.48-0.54, AL 0.85-0.96.

Mandibles very finely longitudinally striate. Anterior clypeal margin with a small, shallow median impression. Median clypeal carina strong, flanked by a pair of carinae which are almost as strongly developed; clypeus otherwise unsculptured except for near the posterior suture where some rugae run onto the clypeus from the frons. Frontal carinae sharp and strong, running back well beyond the level of the posterior margins of the eyes but fading out and merging with the other sculpture on the occiput, some distance in front of the occipital margin. Maximum diameter of the eye 0.17, about 0.22 x HW and with 8-9 ommatidia in the longest row. Propodeal spines long, straight and narrow, much longer than the metapleural lobes; the latter elongate and narrowly triangular, more or less spiniform apically, elevated and slightly upcurved. Petiole in profile with a long anterior peduncle, the anterior face of the node rising vertically and forming a right-angle where it meets the dorsal surface. Dorsum of node in profile shallowly convex and meeting the posterior face in a blunt angle or short curve. Petiole node in dorsal view slightly longer than broad and with a narrow rim or crest running across the anterior margin. Dorsum of head coarsely sculptured with strong longitudinal rugulae, about 10 of which occur between the frontal carinae at the level of the eyes. Spaces between the rugulae with dense and conspicuous finely punctulate or granular ground-sculpture. Occipital region with a number of cross-meshes and anastomoses but without a strong rugoreticulum. Dorsal alitrunk sharply, densely and quite coarsely rugulose, the components meandering but predominantly longitudinal on the pronotum, more disorganized posteriorly. Fine granular or faint punctulate ground-sculpture present between the rugulae. Petiole dorsum finely and very densely rugulose, the components tight-packed and blanketing the surface. Dorsum of postpetiole densely and regularly longitudinally costulate or sulcate, contrasting strongly with the rough and disorganized appearance of the petiole. Gaster smooth and shining. All dorsal surfaces of head and body with numerous standing hairs; the hind tibiae only with short pubescence which is decumbent or appressed. Colour blackish brown to black.

Paratypes: As holotype but maximum diameter of eye 0.14-0.16, about 0.20-0.22 HW and with 8-9 ommatidia in the longest row. Dorsum of head with 8-10 longitudinal rugulae between the frontal carinae at eye level. In some workers the mandibles are virtually smooth, so reduced is the striation. The rugulae on the postpetiole are predominantly transverse in some individuals.

Type Material
Holotype worker, Ghana: Tafo, 8.ii.1970, litter sample (B. Bolton). Paratypes. Ghana: 1 worker with same data as holotype. Ivory Coast: 42 workers, Nzi Noua, N. of Ndouci, 13.i.1977, degraded for., rot. log (W. L. & D. E. Brown). (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.
 * Taylor B., N. Agoinon, A. Sinzogan, A. Adandonon, Y. N'Da Kouagou, S. Bello, R. Wargui, F. Anato, I. Ouagoussounon, H. Houngbo, S. Tchibozo, R. Todjhounde, and J. F. Vayssieres. 2018. Records of ants (Hymenoptera: Formicidae) from the Republic of Benin, with particular reference to the mango farm ecosystem. Journal of Insect Biodiversity 8(1): 006–029.
 * Yeo K., L. M. M. Kouakou, W. Dekoninck, K. Ouattara, and S. Konate. 2016. Detecting intruders: assessment of the anthropophilic ant fauna (Hymenoptera: Formicidae) in the city of Abidjan and along access roads in Banco National Park (Côte d’Ivoire). Journal of Entomology and Zoological Studies 4(4): 351-359.