Tetramorium asetyum

Identification
Bolton (1980) - Only two known species in the sericeiventre-complex of this group have abundant pilosity projecting from the sides of the head behind the eyes, T. asetyum and Tetramorium petersi. Differentiation of the two is given under the latter heading.

Distribution based on Regional Taxon Lists
Afrotropical Region: Nigeria.

Nomenclature

 *  asetyum. Tetramorium asetyum Bolton, 1980: 324, fig. 101 (w.q.) NIGERIA.

Worker
Holotype. TL 4.1, HL 0.94, HW 0.80, CI 85, SL 0.89, SI 111, PW 0.58, AL 1.12. Paratypes (4 measured): TL 3.9-4.1, HL 0.90-0.94, HW 0.74-0.80, CI 81-85, SL 0.86-0.90, SI 111-118, PW 0.54-0.58, AL 1.06-1.14.

Mandibles coarsely longitudinally striate. Anterior clypeal margin entire, without trace of a median notch. Median clypeal carina sharply developed and conspicuous. Frontal carinae very short and feeble, asymmetrical in the holotype, the right-hand side carina ending in front of the level of the anterior margins of the eyes whilst the left-hand side carina runs almost to the level of the midlengths of the eyes before fading out. The paratype specimens have symmetrical carinae varying between ending in front of the eyes and reaching back almost to the level of their posterior margins, but always very feeble and weak. Antennal scrobes absent. Scapes long, SI > 100 (range 111-118 in type-series). Maximum diameter of eyes 0.20, about 0.25 x HW, the longest row with 12-13 ommatidia. Propodeum in profile armed with a pair of spines which are slightly longer than the metapleural lobes, the latter broad basally but narrowly spiniform at the apex. Petiole node in profile long and low, the dorsal length greater than the height of the tergal portion. In dorsal view the petiole node about as long as broad. Dorsum of head finely but strongly longitudinally rugulose, with a weak reticulum occipitally and with a conspicuous reticulate-punctate ground-sculpture everywhere. Dorsal alitrunk longitudinally coarsely rugose, the rugae strongest on the pronotum; ground-sculpture reduced, feeble everywhere on the dorsal alitrunk but particularly inconspicuous on the pronotum, Petiole and postpetiole coarsely rugulose, the spaces between rugulae densely punctate. First gastral tergite densely sculptured everywhere and opaque, the sculpture consisting of very fine punctulae or shagreening, the punctures often aligned (especially basally), giving the impression of extremely fine striation or costulation. All dorsal surfaces of head and body densely clothed with erect or suberect hairs, the propodeal dorsum alone with 4-5 pairs, other surfaces correspondingly densely hairy. With the head in full-face view the sides with numerous stout hairs projecting beyond the outline, those in front of the eyes distinctly longer than those behind; behind the eyes with at least 10 projecting hairs on each side. Dorsal (outer) surfaces of hind tibiae with elongate fine pubescence which is decumbent to appressed. Antennal scapes with short appressed pubescence and also with scattered short hairs which are suberect or subdecumbent. Colour uniform dark brown, with a reddish tint.

Paratypes: Maximum diameter of eye 0.18-0.20, about 0.24-0.26 x HW. As holotype, with the variation noted above. Gastral sculpture is dense and obvious in all members of the type-series, but noting the variation possible in this sculpture in other members of the group it is most probable that more lightly sculptured individuals will be found.

Type Material
Holotype worker, Nigeria: 18 km N. of Mokwa, 29.iv.1977, prey on Pheidole (C. Longhurst). Paratypes. 4 workers and 2 females (one alate), with same data as holotype (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.