Myrmicaria exigua Ern. Andre subspecies kisangani, new subspecies Worker.- Length 3 to 3.5 mm. Head through the eyes scarcely longer than broad, evenly rounded behind. Mandibles 4-toothed. Clypeus ecarinate, convex, with entire, rounded anterior border. Frontal carinae subparallel. Eyes convex, just behind the middle of the head. Antennal scapes extending about two-fifths their length beyond the posterior border of the head; apical funicular joint fusiform, enlarged as in the typical exigua. Pronotum more flattened above, though bluntly angular on the sides and without inferior teeth. Promesonotal suture distinct. Mesonotum with a small but distinct tooth on each side in front and the posterior lobes larger, erect, and rather acute. Mesoepinotal impression very distinct and rather long. Epinotum not longer than broad, scarcely narrowed in front, its base longitudinally grooved in the middle, marginate on each side and not longer than the declivity, which is also marginate laterally; spines not longer than their distance apart at the base, straight, directed backward, upward, and outward, their tips not bent inward as in the typical exigua. Petiolar peduncle as long as the node, swollen at the spiracles; node longer than broad, as high as long, laterally compressed, constricted behind. Postpetiole longer than broad, broader and higher behind than in front, its node distinctly lower than that of the petiole. Anterior border of gaster straight or even slightly concave, with prominent anterior corners. Shining; mandibles subopaque, longitudinally striate. Clypeus smooth in the middle, delicately rugulose on the sides. Head smooth in the middle of the front, delicately and irregularly longitudinally rugulose on the sides, posteriorly reticulaterugose, but much less sharply than in the typical exigua. Pronotum with a few longitudinal rugae, sometimes absent in the middle line; in some specimens reticulatelyrugose over the whole surface, with very large meshes as in exigua. Sides of pronotum smooth and shining; meso- and metapleurae subopaque, longitudinally rugulose. Base of epinotum transversely rugulose, declivity smooth and shining. Pedicel, gaster, and legs smooth and shining, with very sparse and minute, piligerous punctures. Pilosity like that of the typical exigua, gray or whitish. Piceous, nearly black; tips of mandibles, peduncle of petiole, declivity of epinotum, base of postpetiole and in some specimens the whole gaster or only the base of the first segment brown. Described from numerous specimens taken at Stanleyville (Lang and Chapin) "crawling about the base of an orange tree." I have compared this form with two cotypes from Sierra Leone (Mocquerys), received many years ago from Andre, and a worker from Gaboon (Staudinger). The new subspecies differs in its much darker color, feebler sculpture, laterally more compressed petiolar node and in the shape of the mesonotum, which in the typical form of the species lacks the anterior tooth on each side and has only feeble indications of the posterior lobes. Forel has described a variety, rufiventris, from carton nests 3 to 4 cm. in diameter on leaves at St. Gabriel, Lumaliza, and Batiamponde(Kohl), all localities near Stanleyville. This form is larger (3.8 to 4.6 mm.) and, according to Forel, "differs from the type of Andre only in its paler, reddish abdomen and in having the head more elongate and narrower behind." What Stitz has described as a distinct species, gracilis, is evidently nothing more than a subspecies of exigua, as is shown by a comparison of his and Forel's descriptions with the cotypes. André failed to mention the enlarged apical antennal joint, but it is very conspicuous in his specimens. Stitz says of the petiole: "Hinten schnürt sich von seiner Basis ein kleines, sekundäres Knötchen ab." This seems to refer to the swelling of the peduncle at the spiracles, a swelling which is visible, though less accentuated in other species of the genus, when the peduncle is viewed directly from above. Forel, however, interprets Stitz's "secondary node" to mean the constricted portion of the segment behind the node. As neither Stitz nor Forel compared their specimens with Andrews cotypes, they were led to regard gracilis as a species.

Published as part of Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., pp. 39-269 in Bulletin of the American Museum of Natural History 45 on pages 148-149