Ponera Latreille

Schmidt, C. A. & Shattuck, S. O., 2014, The Higher Classification of the Ant Subfamily Ponerinae (Hymenoptera: Formicidae), with a Review of Ponerine Ecology and Behavior, Zootaxa 3817 (1), pp. 1-242 : 200-203

Ponera Latreille

Fig. 48

Ponera Latreille, 1804: 179 (as genus). Type-species: Formica coarctata Latreille, 1802c: 65 ; by subsequent designation of Westwood, 1840: 83.

Pseudocryptopone Wheeler, W.M., 1933a: 12 (as genus). Type-species: Cryptopone tenuis Emery, 1900a: 321 ; by original designation. Wilson, 1957: 356 ( Pseudocryptopone as junior synonym of Ponera ).

Pteroponera Bernard, 1950: 3 (as genus). Type-species: Pteroponera sysphinctoides Bernard, 1950: 4 ; by monotypy. Brown, 1973: 184 ( Pteroponera as junior synonym of Ponera ).

Selenopone Wheeler, W.M., 1933a: 19 (as genus). Type-species: Ponera selenophora Emery, 1900a: 317 ; by original designation. Wilson, 1957: 356 ( Selenopone as junior synonym of Ponera ).

Ponera is a large genus (53 described species) of small cryptobiotic ponerines. Though Asia is the center of Ponera species diversity, a small number of species occur in Europe, Madagascar, and North America.

Diagnosis. Workers of Ponera are superficially similar to those of several other ponerine genera, including Hypoponera , Cryptopone , Euponera and Pseudoponera , but Ponera differs from these genera in having an anterior fenestra in the subpetiolar process. A few species of Hypoponera apparently also have a fenestra, but they lack the paired posterior teeth on the subpetiolar process that are typical of Ponera , and Hypoponera has only a single maxillary palp segment while Ponera has two. Some Belonopelta and Emeryopone also have an anterior fenestra in the subpetiolar process, but these genera have narrow mandibles with long attenuated teeth, while Ponera has typical triangular mandibles with only short teeth.

Synoptic description. Worker. Very small to small (TL 1–4 mm) ants with the standard characters of Ponerini . Mandibles triangular, with numerous small teeth or denticles on the masticatory margin and without a basal groove or pit. Anterior clypeal margin mildly convex, sometimes with a median tooth. Frontal lobes small and closely approximated for nearly their entire length. Antennae often with a four or five segmented apical club. Eyes very small and located very far anterior on the sides of the head. Metanotal groove reduced to a suture. Propodeum broad to mildly narrowed dorsally, with sharp posterior margins. Propodeal spiracles round. Metatibial spur formula (1p). Petiole squamiform, in dorsal view with a convex anterior face and a straight posterior face. Subpetiolar process rectangular or rounded, sometimes with a pair of teeth at the posterior margin and always with a thin spot (fenestra) near the anterior end. Gaster with a strong girdling constriction between pre- and postsclerites of A4. Stridulitrum present on pretergite of A4. Hypopygium rarely with a row of stout spines on each side. Head and body lightly punctate, sometimes with light striations on the sides of the mesosoma and sometimes with smooth and shiny regions of the mesosoma. Head and body with sparse pilosity but a dense pubescence. Color variable, testaceous to black. See the more detailed description in Taylor (1967).

Queen. Similar to worker but winged, with ocelli, larger compound eyes, and the usual modifications of the thoracic sclerites ( Taylor, 1967).

Male. See description by Taylor (1967).

Larva. Described by Wheeler (1900b), Wheeler & Wheeler (1952, 1971a), Taylor (1967), and Escoubas et al. (1987). Ponera larvae have three or four pairs of sticky tubercles with which they are attached to nest walls by workers ( Taylor, 1967).

Geographic distribution. The species diversity of Ponera is highest in eastern and southeastern Asia and Melanesia, with only a few species reaching Australia and points east. Like the distantly related but convergent genus Hypoponera , Ponera seems better adapted to inhabiting temperate regions of the world than most ponerines, as an endemic cluster of Ponera species occurs in Europe and North America. A few species are readily spread by human activity ( Taylor, 1967; Bolton & Fisher, 2011). Two undescribed Ponera species are known from the Malagasy region (Antweb, 2008; but see Bolton & Fisher, 2011), and an undescribed species which may be a Ponera is known from Costa Rica ( Longino, 2013). See Taylor (1967) for a detailed discussion of Ponera biogeography.

Ecology and behavior. The ecology and behavior of Ponera were reviewed by Taylor (1967). We will only briefly summarize his key points and then note additional research. Ponera are among the smallest of all ponerines and are thus well adapted to a cryptobiotic lifestyle. Nests are constructed in rotting wood or under rocks, and colonies are small, usually with around 30 workers, but colonies with up to 60 workers have been reported in P. pennsylvanica ( Wheeler, 1900a) and an average colony size of 60 workers and a maximum observed colony size of 135 workers was reported for P. coarctata (Liebig et al., 1985) . Like Hypoponera , Ponera larvae have specialized sticky tubercles with which workers attach them to nest surfaces, moving them higher to avoid flooding. Ponera are probably generalist arthropod predators, though few direct observations of their food preferences have been observed. In cafeteria-style feeding experiments, various Ponera species in New Guinea accepted diplurans, collembolans, and spiders, but rejected various other prey. Workers are rarely seen foraging on the ground surface, but are collected from leaf litter, moss, rotting wood, and other confined microhabitats. Workers are sluggish and feign death when disturbed ( Wilson, 1957; Pratt et al., 1994). Colony foundation is semi-claustral ( Taylor, 1967).

Pratt et al. (1994) studied the division of labor in colonies of P. pennsylvanica . Most colonies exhibited typical age-related polyethism, with younger workers focusing on brood care and older workers on foraging. Most colonies were monogynous, but some had multiple queens (though the reproductive division of labor among them was unknown). Both winged and ergatoid queens occur in this species (ergatoids have also been reported in P. coarctata: Wheeler, 1900a ). P. pennsylvanica is unusual among ponerines in that it mates in large swarms of reproductives away from the nest ( Haskins, 1970; Peeters, 1991a). Pratt et al. (1994) observed that foraging in this species is generally performed by solitary workers, but groups of workers will sometimes cooperate to retrieve large prey. Tandem running was used during nest emigrations (this has also been reported for P. coarctata : N Carlin, pers. comm. in Hölldobler & Wilson, 1990). See Wheeler (1900a), Kannowski (1959), and Mackay & Anderson (1991) for additional details of the habits of P. pennsylvanica . Johnson (1987) reported on the distribution and ecology of P. exotica .

Liebig et al. (1995) observed queen size polymorphism in P. coarctata , a close relative of P. pennsylvanica , and Liebig et al. (1997) found that workers in orphaned colonies of P. coarctata form dominance hierarchies through aggressive interactions, and that they exchange liquids via trophallaxis as a form of social appeasement (among ponerines, trophallaxis is otherwise only known from some Hypoponera ).

Phylogenetic and taxonomic considerations. Ponera Latreille (1804) is one of the two oldest genus names in the Ponerinae (the other being Odontomachus ), and is the designated type genus of both Ponerinae and Ponerini . For much of the early taxonomic history of the Ponerinae , Ponera served as a sort of default genus into which most new species were placed. This fact is demonstrated by Bolton et al. (2006), who list 312 species and subspecies names which have been transferred out of Ponera and into other ponerine genera (this is nearly as many as are listed for Formica , the oldest ant genus name). Only as the subfamily became gradually more finely divided along generic lines did the current boundaries of Ponera start to take shape.

The identity of the type species of Ponera is somewhat controversial. Latreille (1804) did not designate a type species when first describing the genus, but later ( Latreille, 1810) designated Ponera crassinoda (now Pachycondyla crassinoda ) the type species. Westwood (1840) was either unaware of this designation or chose to ignore it, as he named P. coarctata the type species of Ponera . Emery (1901) later designated P. crassinoda as the type species of Pachycondyla . Subsequent authors have universally used the generic names Ponera and Pachycondyla in the sense of Westwood and Emery. See Taylor (1967) for a more detailed discussion of this issue. We follow recent authors and treat Ponera coarctata as the type species of Ponera .

Ponera has three junior synonyms: Pseudocryptopone Wheeler (1933a) , Selenopone Wheeler (1933a) , and Pteroponera Bernard (1950) , the latter described only from a male specimen and synonymized unceremoniously under Ponera by Brown (1973). In removing several species from Ponera to create his new genera Pseudocryptopone and Selenopone, Wheeler (1933a) admitted the flimsy merits of his new generic distinctions, and Wilson (1957) later agreed, synonymizing Pseudocryptopone and Selenopone back under Ponera . The final major change in the taxonomy of Ponera came with the thorough revision by Taylor (1967). Taylor recognized that “ Ponera ” actually consisted of two unrelated lineages: true Ponera , represented by most of the species formerly placed in Pseudocryptopone and Selenopone , as well as Ponera coarctata and its relatives; and the much larger genus Hypoponera . See Taylor (1967) for a more detailed discussion of the taxonomic history of Ponera .

Schmidt's (2013) molecular phylogeny of the Ponerinae confirms Taylor’s distinction between Ponera and Hypoponera and places Ponera as sister to Ectomomyrmex . This relationship is also supported by morphology ( Taylor, 1967). While there are no obvious synapomorphies linking Ponera and Ectomomyrmex , some species of Ponera (e.g., P. alpha ) are quite similar to Ectomomyrmex ( Taylor, 1967) . It is possible that Ectomomyrmex will prove to be non-monophyletic with respect to Ponera , with the latter genus representing a morphologically reduced clade within Ectomomyrmex . The reverse scenario, with P. alpha as sister to Ectomomyrmex (and Ponera hence non-monophyletic) is also possible but less plausible given the morphological reductions in Ponera ( Taylor, 1967) . Many species of Emeryopone have an anterior fenestra in their subpetiolar process as in Ponera , and this character could represent a synapomorphy of these two genera, though molecular phylogenetic evidence ( Schmidt, 2013) suggests that they are not sisters.

Figures

FIGURE 48. Worker caste of Ponera. Upper specimen: Ponera alpha: lateral and dorsal view of body and full-face view of head (CASENT0172423, April Nobile and www.antweb.org). Lower specimen: Ponera tenuis: lateral view of body and fullface view of head (ANIC32-001503 and CASENT0172429, April Nobile and www.antweb.org); world distribution of Ponera.