Pseudoponera Emery

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 : 205-207

Pseudoponera Emery

Fig. 49

Pseudoponera Emery, 1900a: 314 (as subgenus of Pachycondyla ). Type-species: Ponera quadridentata Smith, F., 1859: 143 (junior synonym of Formica stigma Fabricius, 1804: 400 ); by monotypy.

Trachymesopus Emery, 1911: 84 (as subgenus of Euponera ; in Ponerinae , Ponerini ). Type-species: Formica stigma Fabricius, 1804: 400 ; by original designation. Bolton, 1995: 48 ( Trachymesopus as junior synonym of Pseudoponera , due to synonymous type species).

Trachyponera Santschi, 1928: 43 (incorrect subsequent spelling of Trachymesopus Emery ).

Pseudoponera species are small to medium-sized and found in tropical regions of the Americas and from China south to Australia. The genus currently contains 6 species.

Diagnosis. Workers of Pseudoponera lack any obvious autapomorphies and superficially resemble those of a number of other genera, including Austroponera , Cryptopone , Euponera , Hypoponera , Mesoponera and Rasopone . Separation from these and other genera of the Ponerinae is based on the following set of characters: compound eyes present, mandible with a basal groove (occasionally weakly developed) but no pit, ventral apex of the metatibia with one pectinate and one simple spur, mesosomal profile nearly continuous but interrupted by a shallowly impressed metanotal groove, propodeal spiracle slit-shaped, subpetiolar process without an anterior fenestra and prora present on the anterior margin of the first gastral sternite. Pseudoponera is morphologically most similar to Austroponera and some species of Euponera . It can be separated from Austroponera by the presence of slit-shaped propodeal spiracles (they are round in Austroponera ) and from Euponera by the lack of a basal mandibular pit. Pseudoponera is also similar to Cryptopone , but differs from it in having eyes, lacking a basal pit on the mandibles, and lacking mesotibial traction setae. Pseudoponera workers also strongly resemble those of Hypoponera , but have two metatibial spurs instead of one, generally have wider heads, and tend to be slightly larger. Pseudoponera is similar to Mesoponera but is generally smaller, with denser pilosity, smaller eyes, larger frontal lobes, a wider head, and a broader propodeal dorsum. Workers of Pseudoponera could also conceivably be confused with those of Brachyponera , but these genera differ in their metanotal groove structure (reduced to a suture in Pseudoponera but deeply impressed in Brachyponera ), and Pseudoponera lacks the basal mandibular pits of Brachyponera . Finally, Pseudoponera can be separated from Rasopone by the presence of a basal mandibular groove (occasionally weakly developed) and a slit-shaped rather than round or oval propodeal spiracle.

Synoptic description. Worker. Medium-sized (TL 3.25–5.5 mm) ants with the standard characters of Ponerini . Mandibles triangular, with roughly five to ten teeth and a basal groove (pit absent or obsolete). Anterior margin of clypeus broadly convex. Frontal lobes moderately large and closely approximated. Scapes flattened basally. Eyes very small to small (2-4 facets in diameter), located far anterior on sides of head. Mesopleuron entire. Metanotal groove present as a shallow impression. Metapleural gland orifice orifice without a posterior U-shaped cuticular lip. Propodeum generally narrowing dorsally (more strongly narrowed anteriorly) and with a distinct dorsal face. Propodeal spiracles elongate and slit-like. Metatibial spur formula (1s, 1p). Petiole generally scale-like, rounded dorsally. Gaster with a strong girdling constriction between pre- and postsclerites of A4, stridulatory organ absent. Head and body finely punctate, sometimes with light striations on the sides of the mesosoma, and with abundant pilosity and dense pubescence. Color variable, generally dark brown to ferrugineous.

Queen. Similar to worker but slightly larger, alate, with ocelli and larger compound eyes, and with the modifications of the thoracic sclerites that are typical of alate ponerine queens.

Male. Emery (1911) provided a diagnosis for Pseudoponera males, but he circumscribed the genus differently than it is here and some aspects of his diagnosis may no longer apply. Ogata (1987) provided a description for males of Trachymesopus , which is synonymous with our definition of Pseudoponera (s.s.), but he included Parvaponera darwinii , which we place in a separate genus.

Larva. Described for various species by Wheeler & Wheeler (1952, 1971a, 1976).

Geographic distribution. The majority of species included here in Pseudoponera are Neotropical with a single species occurring in eastern Australia. One species, P. stigma , is widespread in both the Neotropics and the Asia Pacific ( Wetterer, 2012a). It is generally accepted that this is a New World species which has become established in Asia through dispersal by humans. However, Wetterer (2012) points out that there is little direct evidence to support this and the biology of this species is not typical of invasive ants.

Ecology and behavior. Very little is known about the ecology and behavior of Pseudoponera , and the heterogeneous nature of the genus as defined here casts more doubt than usual on any attempt to extrapolate from observations of single species or species groups to the genus as a whole. On the other hand, the taxa placed here in Pseudoponera all share a small body size and apparently cryptobiotic habits, and most of them are probably generalist predators and scavengers. Below are a few brief notes on observations of individual species.

The type species of the genus, P. stigma , is a versatile and adaptable species which can apparently utilize a wide range of habitats and nesting sites ( Longino, 2013; Wetterer, 2012a). Wilson (1958c) reported that in New Guinea this species is forest-dwelling, nests under the bark of rotting logs, forages singly, has a diffuse nest structure, and has independent colony foundation. Wild (2002) reported that P. stigma in Paraguay nests in rotting wood and forages in leaf litter, while in Costa Rica the small colonies of this species have been found from the ground layer up to the canopy ( Longino, 2013). Oliveira et al. (1998) reported on a colony of P. stigma in Brazil which contained 80 workers and was nesting in a rotting log. This colony had multiple dealate queens, but only one of them was mated and succeeded in egg laying. Workers appeared to police egg laying by the other queens. While it is generally accepted that P. stigma is a tramp species distributed by human action, especially in eastern Asia and the Pacific, there seems little biological data to support this position and Wetterer (2012a) questioned where this was truly the case. Longino (2013) provided observations of other Pseudoponera species in Costa Rica, noting that P. cauta is typically found in leaf litter and under wood on the ground, while P. cognata apparently nests in dead wood at ground level or even arboreally.

Phylogenetic and taxonomic considerations. The taxonomic history of Pseudoponera is complex. The genus was erected by Emery (1900a) as a subgenus of Pachycondyla , with Ponera quadridentata (now P. stigma ) as the type species by monotypy. Emery described Pseudoponera as new again the following year ( Emery, 1901), but with Ponera amblyops now designated as the type species. Unfortunately the latter type species was recognized throughout most of the subsequent taxonomic literature (e.g., Emery, 1911), despite P. quadridentata (= P. stigma ) being the true type species by the rules of priority. Bolton (2003) identified and remedied this error.

Emery (1900a, 1901) initially considered Pseudoponera to be a subgenus of Pachycondyla , but subsequent authors alternated between treating it as a separate genus (e.g., Bingham, 1903; Wheeler, 1922b; Donisthorpe, 1943c; also Emery, 1911) or as a subgenus of Euponera (e.g., Forel, 1901a; Emery, 1909; Wheeler, 1910). Pseudoponera was eventually synonymized under Pachycondyla by Brown (1973). We consider Pseudoponera to have a single junior synonym. Trachymesopus Emery (1911) (and its misspelled form Trachyponera Santschi (1928)) is an objective synonym of Pseudoponera as they share the same type species ( Bolton, 1995).

As defined here, Pseudoponera is a collection of small to medium sized cryptobiotic species with no strong synapomorphies linking them to one another. Schmidt's (2013) molecular phylogeny of the Ponerinae includes two species now placed in Pseudoponera : P. stigma (the type species) and an undescribed species from Costa Rica. The P. stigma group is inferred to be sister to the castanea group in this phylogeny, and while similar they are morphologically divergent and the castanea group is here placed in a separate genus, Austroponera . Additionally, while not included in Schmidt’s (2013) phylogeny, our morphological analysis has led us to transfer the Pa. darwinii group from Pseudoponera to a new genus, Parvaponera . This treatment is supported by unpublished data provided by P. S. Ward (pers. comm.), who found Pa. darwinii and two related but unidentified species to be the sister group of P. stigma . Unfortunately these three groups ( Austroponera , Parvaponera and Pseudoponera ) have not been included in a single analysis and therefore the relationships among them are unresolved. However, the available data suggests that they are closely related.

Figures

FIGURE 49. Worker caste of Pseudoponera stigma: lateral and dorsal view of body and full-face view of head (CASENT0178180, April Nobile and www.antweb.org); world distribution of Pseudoponera.