IN THE NEARCTIC REGION THIS IS ONE of the smaller subfamilies of ants, with most species found in the tropical regions of the world. Most of the Nearctic forms are either northern extensions of Neotropical taxa or have been introduced by commerce from other parts of the world. Worldwide there are about 2000 described species and subspecies in subfamily Ponerinae placed in 42 genera (Shattuck, 1999. Ants of Australia). The Nearctic region has 31 species and subspecies in 13 genera.
Most Nearctic species are infrequently encountered and are small cryptic foragers in the soil, leaf litter, and rotten logs. However, in tropical regions, ponerines can be large, conspicuously abundant, and inflict a painful sting. These are primitive ants that nest in small colonies of a few hundred individuals or less, mostly in soil or rotting wood. They are predaceous and carnivorous. Some species are solitary hunters that do not recruit nestmates to food sources - a primitive behavioral trait.
Due primarily to the revisionary work of W.L. Brown Jr., the grouping of genera into a tribe rank classification is more or less accurate and reflects an acceptable classification (Bolton, 1995b: 8). Most genera are well defined, the generic limits are relatively clear, and many junior synonyms have been identified. This contrasts with subfamily Formicinae in which the tribal and generic structure requires further clarification and, especially, with subfamily Myrmicinae in which they are in chaos. (Myrmicinae is currently under review by Barry Bolton.)
Subfamily Ponerinae has long been considered a monophyletic group with every single genus exhibiting a synapomorphy found nowhere else in the ants - fusion of the tergite and sternite of abdominal segment IV (= gastral segment II). However, a recent discovery threatens to upset the established order. In a tropical dry forest in Madagascar, Phil Ward made a single collection of a small, subterranean ant (Ward, 1994). By virtue of a large number of shared characteristics, it is clearly a member of tribe Amblyoponini in subfamily Ponerinae. This new genus, Adetomyrma, lacks the fusion of tergite and sternite in abdominal segment IV. It is generally believed that sclerite fusion is an unreversable trait. This leaves no clear explanation of Adetomyrma. It is possible that the future may see the ponerines broken up (see Grimaldi, Agosti & Carpenter, 1997. Am. Mus. Novitat. 3208).
The relationship of Ponerinae to the other subfamilies of ants is also unclear. Historically, it has been considered a sister group of Myrmicinae, and that an ancestral ponerine gave rise to the army ants (subfamilies Aenictinae, Cerapachyinae, Dorylinae, Ecitoninae, and Leptanillinae) (Hölldobler & Wilson, 1990: 26). A recent phylogeny of the subfamilies (Baroni Urbani, Bolton & Ward, 1992) removes Myrmicinae to a clade distant from Ponerinae, but leaves the ponerines as the sister group of the army ants. As with much of our understanding of the evolution of the ants, this picture may once again be revised.
Recognition. The mesosoma is attached to the gaster by a single segment, the petiole. The gaster usually has a slight but distinct constriction between the first and second segments. (Exceptions: i) genus Discothyrea, the gaster is highly modified and the impression is weak or absent, but in these the gaster is strongly arched and the tip of the gaster is directed forward and downward ii) in Anochetus and Odontomachus the gaster is smooth and uniform, but the mandibles are long and straight and they are inserted in the middle of the anterior margin of the head.) The upper surface of the tip of the gaster (the pygidium) is rounded and lacks a row of spines or teeth on its outer and trailing edge. The sting is present although sometimes retracted and difficult to see.
Taxonomy. Wheeler, 1910b: 225-245 (oeverview of subfamily, natural history). || Brown, 1958g: 175-362 (revision of Ectatommini sensu. latu., including Proceratium and Discothyrea). || Brown, 1960a: 145-230 (Amblyoponini). || Brown, 1975: 4–11 (Platythyreini - world genera and species, keys to species, some biological information). || Kugler, C. 1991: 153-166 (sting structure). || Hashimoto, 1991a: 125-140 (sensillum structures on antennae and labial palpi; see especially table 2). || Bolton, 1994: (153-165, figs.) (detailed diagnosis of w., keys to world genera, SEMs [full face and lateral view] of each genus, bibliography). || Lattke, 1994: 105-119 (characterization and phylogeny of genera in Ectatommini, Proceratini, and Paraponerinin). || Ward, 1994: 167-171 (redefenition of Amblyoponini). || Keller, R.A. 2000. Insect Systematic and Evolution31: 59-69 (phylogeny of Ectatommini, reevaluation of Lattke, 1994).
Nearctic Genera.Amblyopone, Anochetus, Cryptopone, Discothyrea, Ectatomma, Gnamptogenys, Hypoponera, Leptogenys, Odontomachus, Pachycondyla, Platythyrea, Ponera, Prionopelta, Proceratium.
Non-Nearctic Genera. Acanthoponera, Adetomyrma, Asphinctopone, Aulacopone, Bannapone, Belonopelta, Centromyrmex, Concoctio, Condylodon, Diacamma, Dinoponera, Dolioponera, Emeryopone, Harpegnathos, Heteroponera, Myopias, Myopopone, Mystrium, Odontoponera, Onychomyrmex, Paraponera, Paraprionopelta, Phrynoponera, Plectroctena, Probolomyrmex (recently transferred to its own, monotypic subfamily, Probolomyrmicinae), Psalidomyrmex, Rhytidoponera, Simopelta, Streblognathus, Thaumatomyrmex, Typhlomyrmex.
Included Tribes.