Tetramorium youngi

Identification
Bolton (1980) - Within the setigerum-group T. youngi is most closely related to Tetramorium metactum, but is slightly smaller than that species, has shorter antennal scapes and has more weakly developed sculpture. In particular, T. youngi lacks cross-meshes on the dorsum of the head and also lacks an occipital reticulum, both of which are present in T. metactum. Also, T. metactum has traces of rugular sculpture on the sides of the petiole and coarser more dense rugosity on the dorsal alitrunk. More distantly both T. youngi and T. metactum seem to be related to Tetramorium perlongum and Tetramorium dolichosum, but both these species are quickly separated by their exceptionally long appendages (SI > 150), more feebly developed frontal carinae and rounded metapleural lobes.

Distribution based on Regional Taxon Lists
Afrotropical Region: Angola.

Nomenclature

 *  youngi. Tetramorium youngi Bolton, 1980: 284 (w.) ANGOLA.

Worker
Holotype. TL 3.4, HL 0.76, HW 0.64, CI 84, SL 0.67, SI 105, PW 0.50, AL 0.98. Mandibles longitudinally striate. Anterior clypeal margin evenly convex, without median notch or impression. Clypeus with 3 longitudinal carinae only. Frontal carinae long, reaching back almost to the occipital margin but not strongly developed, only slightly stronger than the longitudinal rugae between them; maximum separation of the carinae is about 0.53 x HW. Antennal scrobes narrow and shallow, weakly developed. Scapes relatively long, SI > 100. Maximum diameter of eye 0.17, about 0.27 x HW. With the alitrunk in profile the metanotal groove impressed. Propodeal spines very long, narrow and acute apically and feebly downcurved along their length. Metapleural lobes short-triangular and acute, their apices slightly upcurved. Petiole in profile with a long anterior peduncle and short node. The anterior and posterior faces of the node slope towards one another so that the node is somewhat narrower above than below. Dorsum of node very shallowly convex and the posterodorsal angle more rounded than the anterodorsal. Postpetiole in profile with the anterior and dorsal surfaces forming a single continuous curve; the posterior face almost vertical, much steeper than the anterior. Petiole node in dorsal view slightly longer than broad, the postpetiole about as long as broad but much narrower in front than behind. Dorsum of head with 5 longitudinal rugulae between the frontal carinae, the outer members of which are broken or discontinuous. Spaces between rugulae virtually smooth, with only the faintest traces of ground-sculpture. Occipital region without a reticulum. Dorsal alitrunk unevenly rugose but the constituents widely separated by smooth spaces and predominantly longitudinal on the pronotum. Petiole, postpetiole and first gastral tergite unsculptured, smooth and shining. All dorsal surfaces of head and body with numerous standing hairs. Scapes and tibiae only with fine, short, decumbent to appressed pubescence. Head and body glossy blackish brown, the appendages pale yellow.

Type Material
Holotype worker, Angola: Salazar, 1.1.A.A., 9-15.iii 1972 (A26) (P. M. Hammond).

References based on Global Ant Biodiversity Informatics

 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research 3: 5-16.
 * Belshaw R., and B. Bolton. 1994. A survey of the leaf litter ant fauna in Ghana, West Africa (Hymenoptera: Formicidae). Journal of Hymenoptera Research. 3: 5-16.
 * 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.