(Figs. 46, 47, 50)
Holotype worker: TL 5.3, HL 1.00, HW 0.97 (CI 97), ML 0.19, WL 1.44, petiolar node L 0.51, petiolar node W 0.74, antennal scape L 0.56, greatest diameter of eye 0.30 mm (largest worker of type series).
Paratype workers: Measurements are of smallest paratype: TL 4.8, HL 0.94, HW 0.87 (CI 93), ML 0.15, WL 1.30, petiolar node L 0.48, petiolar node W 0.69, antennal scape L 0.51, greatest diameter of eye 0.28 mm.
Compound description: Form of head and body as in figs. 46 and 47. In larger specimens, head very nearly as broad as long; ignoring anterior projections over the mandibles, width is equal to or very slightly greater than length. In small specimens, head slightly narrower in relation to length. This is a thickset species with large, posteriorly placed eyes. A few of the larger specimens also have a weakly developed median ocellus, or ocellar pit, and in at least 2 specimens, minute, paired, posterior ocelli or pits are present.
Characters to be especially noted are the lack of a median tooth or tubercle on the clypeus; the obliquely raised, separated, frontal lobes and carinae; the large, smooth, impressed area mesad of each eye, serving as a demiscrobe for the unusually large, thick 12 - merous antennae; and, bordering each impressed area laterad, the distinct anteocular groove connecting the circumocular (orbital) groove with the lateral carina of the cheek. The scapes reach to about the middle of the eyes; apical segment of antenna about 3 X as long as penultimate segment, and slightly thicker. Palpi segmented 3,2, the two segments of the labial palpi both long.
Trunk boxlike, with sutureless dorsum gently convex in both directions; pleura vertical, curving sharply into dorsum above. Pronotum sharply marginate anteriorly, with a groove inside the margin; this groove, becoming wider and deeper ventrad, crosses the lower part of each side of the pronotum and continues horizontally across the middle of the side of the mesothorax as a deep mesopleural suture, then curves downward to form the suture between meso- and metapleuron. There is also a horizontal sulcus each, both above and below the meatus of the metapleural gland. Propodeal declivity concave, bounded above and on the sides by a narrow, raised margin or carina. Propodeal spiracle situated down low, small, and nearly circular.
Petiole shown in figs. 47 and 50; note the concave dorsal surface and marginate anterodorsal edge, the latter very slightly convex in the middle, but otherwise straight. Sides of petiole steep, but not separated from dorsum by a margin. The longitudinal striation of the disc is distinctive. Postpetiole-gaster as shown in fig. 47. Sting stout. Pygidium with a smooth, shining, impressed disc, its laterapical margins raised, bearing a row of sharp denticles.
Body surface smooth, with widely spaced, moderately coarse punctures, mostly piligerous, sparse on sides of trunk. Concave areas inside eyes and anterior clypeus impunctate; cheeks mesad of carinae, tibiae and tarsi, and sides of pygidium densely, finely, indistinctly punctulate, subopaque. Pilosity of fine, slightly curved hairs of moderate length, mostly decumbent to subdecumbent, fairly abundant (fig. 47), longest on gaster; shorter and dense on legs and antennae. Longer hairs more nearly erect in some speciments. Body black, with a rich, opalescent blue sheen; antennal funiculi, legs, and apex of gaster brown.
Apical tibial spurs narrowly pectinate, the posterior pair slightly larger than those of middle legs; tarsal claws slender and simple.
Queen and male unknown, unless some of the ocellate individuals act as queens.
Holotype (MCZ) and paratype (MCZ, BMNH, and elsewhere) from a series of 21 workers taken running in broken file over logs in wet forest near Perinet, on the rail line from Tananarive to Tamatave in Madagascar (Brown leg.). Some of the ants were carrying white pharate adults of a small Pheidole species, and they disappeared into cracks in a large rotten log that could not be opened with the tools available.
This species occupies a taxonomic position of special importance, because it links the old Cerapachys s. str. with Phyracaces (by antennal form and shape of petiole) on the one hand, and with Simopone (by separate, merely obliquely raised frontal lobes, demiscrobes, and very large eyes) on the other. The concave, medially striate disc of the petiolar node will serve to distinguish C. lividus from all congeners.
