Apomyrma

In the original description (Brown et. al 1970) the authors suggest this species lives an entirely subterranean existence, primarily inhabits tropical forests, and belongs to a guild of centipede feeding ants. It was also stated that "Apomyrma, like many other other subterranean predatory ponerines, moves deep (30 cm or more) into the soil during the dry season (October to April), but during the rainy season it comes up to within 10 cm of the surface."

Identification
In the field and with the naked eye resembles a small, slender, shining Stigmatomma. Possesses a pedunculate petiole with no differentiated postpetiole. Helium attached low down on the anterior face of abdominal segment 3 (see figure in the Nomenclature section).

Biology
The few known nests of the single species of this genus were found in soil nests and contained less than 100 individuals.

Castes
The type species description notes there are small and large form workers, with the variation being found between nests. The former are ~ 2 mm in total length while the latter are ~3 mm in total length and are generally more robust.

Ergatoid queens were found in the nest of the type series.

Nomenclature

 *  APOMYRMA [Amblyoponinae]
 * Apomyrma Brown, Gotwald & Lévieux, 1971: 259. Type-species: Apomyrma stygia, by original designation.

Description
Worker: Habitus in life and to the naked eye much that of a very small, slender, shining Amblyopone. Also reminiscent of Leptanilla.

Head oblong, depressed, parallel-sided, with rounded corners (like that of many female pristocerine Bethylidae), anterior corners of head unarmed. Eyes and ocelli lacking. Antennae 12-segmented, scapes very short and clavate, funiculus robust, with an indistinct 4-merous club. Antennal sockets round, impressed, completely exposed, the frontal carinae extremely reduced and indistinguishably fused with the reduced median portion of the clypeus to produce a small, subtriangular tumulus or convex platform that trails a brief septum posteriad scarcely beyond the level of the posterior socket rims (see Fig. 5). Clypeus, except for the small raised median portion, impressed, very narrow and not distinctly demarcated behind, its anterior border shallowly but broadly concave, unarmed. The basal part of the labrum forms a straight line within the clypeal concavity, and bears a row (actually backed by a second row) of peg-like teeth that seem at first sight to spring from the clypeal margin. These teeth fill the narrow space between the clypeus and the normally closed mandible. Mandibles short, gently curved, and linear, with bidentate apex and a few blunt, spaced teeth on apical half of inner border. Labrum broader than long, .sides converging distad; apex broadly emarginate; extensor surface with two irregular rows of peg-like teeth (or modified hairs) on basal half. Maxilla simplified from form of Stigmatomma pallipes (see Gotwald, 1969), without galeal comb, and galeal crown smoothly continuing the dorsal galeal margin; maxillary palpus 2-segmented. Labium apparently without paraglossal lobes; setae of subglossal brushes tapered to apices; labial palpi 2-segmented.

Truncus (= alitrunk, = thorax + propodeum) long and slender, consisting of a convex, immarginate pronotum into which is flexibly fitted a slightly longer oblong portion consisting mainly of propodeum, meso- and metathorax; mesonotum reduced to a narrow, depressed transverse strip largely covered by posterior edge of pronotum except when pronotum is flexed downward. Propodeal dorsum almost flat (weakly convex), immarginate but with pleura perpendicular; declivity strongly convex, immarginate and unarmed, overhanging lower part and orifice. Bulla of metapleural gland conspicuously outlined through cuticle, subcircular; propodeal spiracle contiguous with it anteriad. Coxae nearly the same size (anterior coxa largest); femora short and strongly incrassate toward their middle; tarsi short, slender at base but gradually becoming thicker to near their apices. Tibial spurs 1, 2, 2, the middle and posterior legs each with one large, broadly pectinate inner spur and a smaller, more slender, sparsely pectinate outer one. Metatarsus of anterior legs strongly curved, opposing the large pectinate tibial spur; other metatarsi straight, weakly clavate. Tarsal claws small, slender, simple.

Petiole with a massive subcubical node, a brief, slender, but distinct anterior peduncle, and a very short posterior peduncle. Both anterior and posterior faces of the node are vertical, and the petiole is connected to the gaster only by the narrowly strangulated connection of the posterior petiolar peduncle to the short anterior peduncle of the first gastric (postpetiolar) segment. Postpetiole (first gastric segment true abdominal segment III) reduced in size, only slightly broader than petiole; much smaller than the following segment, and showing a very slight beginning of constriction from the latter (constriction a little more distinct in the queen). Sternum of postpetiole especially reduced, only weakly convex and with only a suggestion of bilateral anteroventral processes on either side of a shallow anteromedian impression. Second gastric (IV abdominal) segment the longest, widest and deepest of the gaster; larger than the remaining apical segments taken together; these taper to a rounded apex from which issues a very long, slender, curved sting. Postpetiolar tergum and the terga of all succeeding segments of gaster easily and cleanly separable from sterna.

Entire body shining, smooth, with abundant small, distinct, spaced punctures on dorsum of head, becoming fewer and smaller on truncus and remainder of body; legs and antennal funiculae becoming more densely and finely punctulate apicad; cervix and a few other areas on sides of truncus and node loosely reticulate. Entire body (except lower sides of truncus) and appendages covered densely (more sparsely on under.side of petiole and gaster) with short, fine, pointed hairs.

Color ferruginous yellow; mandibles and appendages lighter yellow.

Queen, alate: Like the worker in general form of body, but more robust overall. Eyes well-developed, pigmented and moderately convex, with about 10 facets across the greatest diameter, situated far back, at about the posterior quarter of the head length. Ocelli developed, situated between compound eyes. Pterothorax well developed but nearly flat, continuing the nearly straight (very feebly convex) dorsal profile of the truncus as seen from the side. Scutum, prescutellum (= axillary area) and scutellum all developed, flat, the scutum without recognizable notauli or parapsidal furrows. Wings delicate, hyaline, microtrichiate.

The second and third free abscissae of Rs are wanting, creating a large cubital cell; Mf4 is completely lacking, and there is even a small gap left at its former origin at the angle between Mf3 and r-m, so that the cubital cell is not completely closed at its posterodistal corner (Fig. 7). Rs narrowly recurved into costal margin about halfway between pterostigma and wing apex, thus enclosing a fairly long radial cell; except for Rs, apical half of wing membrane without veins. Hind wing narrow, acutely rounded, venation restricted to R + Sc, which fades out before reaching midwing; hamuli small and weak, 5 in number in the specimen counted; no anal lobe.

Petiolar node and gaster a little wider than in worker, and the incipient constriction between postpetiole and succeeding segment a bit more distinct. Form of body, sculpture, pilosity and color otherwise much as in worker (the pilosity may be slightly more abundant and a bit longer.)

Additional References
William L. Brown, William H. Gotwald Jr., and Jean Levieux, Jr., "A New Genus of Ponerine Ants From West Africa (Hymenoptera: Formicidae) With Ecological Notes," Psyche, vol. 77, no. 3, pp. 259-275, 1970. doi:10.1155/1970/64703