Trachymyrmex agudensis, Kempf, W. W., 1967

Kempf, W. W., 1967, New ants from southeastern and central Brazil (Hymenoptera, Formicidae)., Studia Entomologica (N. S.) 9, pp. 121-128 : 124-125

Trachymyrmex agudensis n. sp.

(Figs. 4-6)

Worker (holotype). - Total length 6.5 mm; head length 1.52 mm; head width 1.36 mm; scape length 1.28 mm; maximum diameter of eyes 0.25 mm; thorax length 2.03 mm; hind femur length 2.13 mm; petiole length/width 0.48/0.30 mm; postpetiole length/width 0.50/0.50 mm. Color light reddish brown; mandibles, antennae, legs considerably darker; gaster mostly infuscated. Hairs black, often with brownish tips, of variable length, bristly, standing or. curved, moderately abundant on body and legs. Conspicuous pubescence only on funiculi, tibiae and tarsi. Integument basically smooth and shining but secondarily covered by a thin and transparent film (of some secretion?) which renders it opaque. Piligerous tubercles mostly absent on body.

Head as shown in Fig. 4. Mandibles smooth and shining apicad and mesad, finely striate basad and laterad; chewing border with approximately 10 teeth, becoming gradually smaller and even obsolete towards base. Clypeus: anterior border deeply notched in the middle; mesial portion oblique, its sides marginate; posterior portion and frontal area somewhat impressed between triangular, laterally irregularly denticulate frontal lobes; frontal area prolonged caudad in the shape of a faint, finger-like, distinctly circumscribed impression. Frontal carinae moderately diverging caudad, their posterior fourth obsolete, not reaching back to the blunt, prominent, denticulate, upper-mesial occipital corner. Preocular carinae split into two branches at level of eyes, the lateral branch fading out at posterior fifth of head, the mesial one slightly behind eyes. Hence the antennal scrobe is not sharply delimited caudad. Eyes flat, kidney-shaped, with nearly 20 facets across greatest diameter. No distinct supraocular tumulus, but instead a series of minute teeth. Lateral occipital corner having the form of a somewhat denticulate spine. Inferior occipital corner subangulate in side-view. Inferior border of head immarginate. Occiput deeply notched in the middle. Vertex with a pair of rather vestigial longitudinal carinae. Antennal scape barely reaching tip of occipital spine, its basal fifth smooth, the rest sparsely but coarsely denticulate, its leading edge immarginate. All funicular segments considerably longer than broad.

Thorax as shown in Fig. 5. Pronotum: paired median denticles extremely small, vestigial, separate, lateral spines huge, sparsely denticulate; antero-inferior corner with a long, fingerlike spine; laterotergite with a short denticulate ridge above denticulate inferior border. Anterior mesonotal spines longer and stouter than lateral pronotal ones, denticulate, followed posteriorly by two more pairs, the second pair less than half as long as first, the third in the form of short teeth. Mesoepinotal constriction considerable, lacking a suture. Basal face of epinotum anteriorly with a pair of convex denticulate crests, posteriorly with a short tooth on each corner. Mesopleural lobe broad and apically rounded. Epinotal spiracle protruding. Long, terete femora beset with sparse denticles.

Petiole and postpetiole as shown in Figs. 5 and 6. Both lacking dorsally projecting, piligerous denticles, but having the same sparsely on sides. Dorsum of postpetiole dorsally flattened, postero-mesially shallowly impressed; posterior border scarcely excised. Tergum 1 of gaster with 4 longitudinal, denticulate, low and rather blunt keels, the lateral ones a bit sharper and better developed than the mesial ones, extending over anterior two thirds of tergum. Piligerous tubercles developed on keels and on posterior third of tergum I. Sternum I with a sharp, low median keel on anterior half.

Female and male unknown.

Specimens examined: 2 workers (holotype and paratype) from Brazil, Sao Paulo State, Agudos, Fazenda Sto. Antonio, C. Gilbert leg., May 1959 (WWK n. 4429).

The paratype agrees completely with the holotype, even as regards the essential measurements.

Discussion. - This is a rather striking species, characterized principally by the smooth integument; the large, flat, kidney-shaped eyes; the split preocular carinae; the poor development of the median pronotal denticles; the extremely small epinotal teeth; the lack of denticles dorsally on petiole and postpetiole; the shape of the mesopleural lobes; the keeled tergum 1 of gaster.

In southeastern Brazil, its closest relatives are urichi and oetkeri , from which agudensis differs in smoother integument, triangular rather than subsemicircular frontal lobes, lack of a distinct supraocular tumulus, poorly developed but widely separate midpronotal teeth; shape of mesopleural lobes, poorly developed epinotal spines.