Tetramorium degener Santschi

Tetramorium (Xyphomyrmex) [sic] degener Santschi, 1911: 124. Holotype worker, Madagascar (J. de Gaulle) (NM, Basle) [examined]. [Data label on holotype states: T. (X.) ranarum r. degener.]

Worker. TL 2.1 - 2.5, HL 0.58 - 0.60, HW 0.52 - 0.55, CI 89 - 93, SL 0.37 - 0.40, SI 69 - 74, PW 0.38 - 0.42, AL 0.60 - 0.66 (10 measured).

Mandibles longitudinally striate, anterior clypeal margin with a shallow notch or indentation medially which may be difficult to see in some specimens. Frontal carinae distinct to well beyond the level of the eyes but fading out in the posterior quarter of the head-length and becoming indistinguishable from the remaining cephalic sculpture. Antennal scrobes shallow but conspicuous in full-face view, the lower part of the scrobal area with reticular sculpture. Eyes of moderate size, maximum diameter c. 0.12, about 0.22 x HW. Propodeum with a pair of stout triangular spines, the metapleural lobes triangular and acute. Node of petiole in profile higher than the dorsum is long, with roughly parallel anterior and posterior faces and a feebly convex dorsum. In dorsal view the petiole node very slightly broader than long. Postpetiole evenly convex in profile. Head with fine longitudinal rugulation dorsally, which becomes reticulate occipitally. Interspaces with a very feeble superficial punctulation. Dorsal alitrunk reticulate-rugulose, best developed on the pronotum, the rugulae fine and sharply defined, not having a beaded appearance dorsally.

Postpetiole and gaster always unsculptured but the petiole dorsum often with traces of sculpture present. All dorsal surfaces of head and body with numerous fine hairs, mainly erect or suberect. Colour uniform light brown, the appendages lighter.

T. degener is a small species characterized by its moderately sized eyes and sharply defined sculpture. It is closest related to quasirum, a similar-sized species, but here the sculpture of the dorsal alitrunk is low and blunted, the upper surface with a beaded appearance due to the presence of fine aligned punctulation. Similar sculpture is present on the pronotum of coillum and ranarum, but this latter species averages larger and has relatively small eyes, and the former retains traces of rugulose sculpture on the postpetiole.

Material examined

Madagascar: Perinei (W. L. Brown).