Carebara osborni, Wheeler, W. M., 1922

Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., Bulletin of the American Museum of Natural History 45, pp. 39-269 : 174-176

Carebara osborni , new species

Plate XV; Text Figure 41

Worker.- Length 0.8 to 1 mm.

Head subrectangular, slightly longer than broad, as broad in front as behind, with nearly straight posterior and very feebly and evenly rounded lateral borders. Eyes absent. Mandibles convex, with oblique 4-toothed apical borders. Antennae 9-jointed, the scapes reaching to the middle of the sides of the head; funicular joints 2 to 6 very small, slightly broader than long (too long in the figure), terminal joint longer than the remainder of the funiculus (too short in the figure). Thorax narrower than the head; pro- and mesonotum flattened above, suboctagonal, a little longer than broad; epinotum subcuboidal, of the same height as the promesonotum but narrower, as long as broad, the base and declivity subequal in profile, meeting at a right angle, the base not marginate on the sides, the declivity in the middle sloping and longer than the base. Mesoepinotal suture very distinct but not impressed. Petiolar node as long as broad, subglobular, peduncle short; postpetiole not broader than the petiole, with much smaller node. Gaster and legs of the usual shape.

Shining; mandibles finely and sparsely punctate; head and thorax above coarsely punctate, the latter more sparsely; punctures on the remainder of the body finer and sparser.

Hairs pale yellow, short, subappressed, not very abundant, most distinct on the gaster.

Pale brownish yellow, mandibular teeth and anterior border of clypeus darker brown.

Female (dealated).- Length 8 mm.

Head, including the mandibles, as long as broad, broader behind than in front, with feebly convex posterior border, rounded posterior corners and straight cheeks. Eyes not very convex, on the sides of the head. Ocelli large, in deep impressions. Mandibles large, with oblique, 4-toothed apical borders. Clypeus with a broad longitudinal median impression, its anterior border broadly and sinuately emarginate in the middle. Frontal area absent, represented only by the impressed anterior end of the rather deep frontal groove. Frontal carinae slightly flattened, scarcely diverging behind. Antennae short, 10-jointed, scapes reaching to the posterior orbits; funicular joints 2 to 5 broader than long; joint 6 as long as broad, joint 7 somewhat more than half as long as joint 8, the terminal joint equal to joints 7 and 8 together. Thorax robust, longer than broad, broader than the head; the mesonotum convex, longer than broad, in front scarcely overarching the vertical pronotum, parapsidal furrows very distinct. Epinotum longitudinally grooved in the middle, with short base and a much longer, abrupt, rather flat declivity, bordered on each side by a large, flat, rounded and marginate lobe or crest. Petiolar node from above broadly oval, nearly as long as broad, evenly convex and rounded above, its anterior slope with a median blunt convexity, its ventral border in profile slightly concave in the middle. Postpetiole from above a little broader than the petiole, about one and two-thirds times as broad as long, convex above in front. Gaster broadly elliptical, somewhat flattened dorsally and ventrally. Legs rather short.

Shining; mandibles, head, epinotum, and sides and ventral portions of petiole and postpetiole more opaque. Mandibles very coarsely striatopunctate. Clypeus irregularly and indistinctly rugulose, somewhat transversely in the middle. Head coarsely and umbilicately punctate, finely striate in the spaces between the punctures. Mesonotum, scutellum, mesopleurae, gaster, and nodes of petiole and postpetiole covered with umbilicate punctures of the same size as those on the head but sparser and with the shining interspaces very minutely and sparsely punctate. Opaque portions of epinotum and pedicel very finely striate. Legs with larger and minute punctures like the gaster, but the larger punctures are smaller and denser. Antennal scapes finely and densely punctate.

Hairs yellow, short, bristly, suberect, rather uniformly distributed over the body, arising from the large umbilicate punctures, longer on the gula and tip of the gaster, more abundant on the latter; very short, delicate and appressed on the legs and scapes.

Reddish brown; gaster and legs somewhat paler; mesonotum with indistinct traces of castaneous stripes, especially posteriorly. Mandibular teeth blackish.

Male.- Length 7 to 7.5 mm.

Head through the eyes much broader than long, broadest at the median transverse diameter, short and rounded behind. Eyes very large; ocelli large and prominent. Mandibles narrow, 3-toothed. Clypeus very convex and rounded in the middle with projecting, entire anterior border. Antennae 13-jointed, long, filiform, of uniform thickness; scapes about three times as long as the first funicular joint, which is as broad as long but not swollen; remaining joints cylindrical, fully three times as long as broad, the terminal joint longer. Thorax robust, nearly as broad as long, through the wing insertions slightly broader than the head, convex above, in front somewhat overarching the pronotum. Epinotum short, shaped like that of the female, but without the marginate projections on the sides. Petiole resembling that of the female but with node scarcely developed; postpetiole much less convex, longer in proportion to its length. Gaster rather slender, scarcely flattened above; external genitalia voluminous, more or less exserted, the outer valves large, rounded at their tips. Legs slender.

Subopaque; scutellum, gaster, and upper surfaces of petiolar and postpetiolar nodes shining. Mandibles, head, thorax, and pedicel very finely and densely punctate; gaster also with fine but sparser punctures, those on the scutellum coarser but not so dense as on the remainder of the thorax.

Hairs finer, much shorter, and denser and more appressed on all parts of the body than in the female.

Brown; ocellar region black. Wings brownish, rather opaque, with the veins and pterostigma of the same color as the body.

Described from four workers, one female, and numerous males taken from a single colony at Niangara (Lang and Chapin) in the mound of a termite (Termes natalensis Haviland). According to Mr. Lang, the specimens were found "south of Niangara in one of the grass-covered termite hills which give the treeless landscape of the savannah its characteristic appearance (Plate XV). These hills extend as far as the eye can reach. They are never very high - rarely more than twelve feet - though they may attain a diameter of fifty feet at the base. Usually they appear as mere undulations of the ground, covered with grass which may be as much as ten feet high. The Carebara queen, males and workers were living in a flattened chamber about three feet above the general level of the soil near the center of a medium-sized termitarium."

C. osborni , though a true Carebara , is entirely unlike any of the known species in the small size of all the phases. In this respect and in the color of the male and female it approaches the species of the genus Oligomyrmex .