Tetramorium psymanum

Identification
Bolton (1980) - Closely related to Tetramorium meressei and sharing the dense pilosity and characteristically shaped postpetiole of that species, T. psymanum and T. meressei form a discrete complex within the dumezi-group. Like the members of the larger dumezi-complex T. meressei and T. psymanum have smooth mandibles and an entire anterior clypeal margin, but unlike them they have a dense pelt of elongate fine soft hair, and a high postpetiole with an abrupt, vertical posterior face. The principal characters separating meressei from T. psymanum are that T. meressei is yellow, has propodeal teeth present, has rounded dorsal petiolar angles, and has the mesonotum and propodeum much less strongly sculptured than the pronotum.

Distribution based on Regional Taxon Lists
Afrotropical Region: Ghana.

Nomenclature

 *  psymanum. Tetramorium psymanum Bolton, 1980: 351 (w.) GHANA.

A third species of the meressei-complex (dumezi species group) is represented by a single badly-damaged specimen originating from Nkoemvon in Cameroun. It is close to T. psymanum in most respects but the petiole node is lower and has rugular sculpture conspicuous on the sides. The head is less densely but more sharply sculptured and has a loose occipital rugoreticulum; ground-sculpture is virtually absent. Although this specimen represents a third distinct species in this complex I do not intend to name it here as the postpetiole and gaster are missing and much of the pilosity has been abraded away.

Worker
TL 3.1, HL 0.72, HW 0.56, CI 78, SL 0.47, SI 84, PW 0.44, AL 0.88.

Mandibles smooth and shining with scattered minute pits. Anterior clypeal margin entire, without trace of a median notch. Clypeus with a median carina and with 2 flanking pairs, the inner pair of which is slightly stronger. Frontal carinae fine and narrow, reaching back well beyond the level of the posterior margins of the eyes but fading out on the occiput and merging with the sculpture there. Maximum diameter of eye 0.15, about 0.27 x HW and with 8 ommatidia in the longest row. Sides of head in full-face view roughly parallel, not evenly convex. Propodeum armed with a minute tubercle or merely angulate, without strong teeth. Metapleural lobes broadly triangular, much more massive than the propodeal armament. Petiole node in profile high, tapering from base to apex as the anterior and posterior faces converge dorsally, the dorsal length less than the height of the tergal portion of the node. Antero- and posterodorsal angles of the node present but blunted. In dorsal view the petiole node roughly globular, about as broad as long. Postpetiole in profile higher than the petiole; the anterior face a steeply ascending shallow convexity, the dorsum narrowly rounded and the posterior face vertical and abrupt. Dorsum of head finely irregularly longitudinally rugulose with a few cross-meshes and anastomoses occipitally and with a weak superficial granular or punctulate ground-sculpture between the rugulae. Dorsal alitrunk irregularly densely rugulose everywhere, in places forming a loose reticulum or open-meshed net but the sculpture about equally strongly developed everywhere. Dorsal petiole and postpetiole unsculptured but the sides with vestigial traces of sculpture. First gastral tergite unsculptured. All dorsal surfaces of head and body covered by a dense coat of elongate, fine curved acute hairs. Leading edges of antennal scapes with projecting fine pubescence which is predominantly suberect. Dorsal (outer) surfaces of middle and hind tibiae with abundant fine erect long hairs similar to those on the body. Colour uniform mid-brown, the appendages lighter.

Type Material
Holotype worker, Ghana: Bunso, 15.vii.1969, ant ecology sample x 20 (D. Leston).