Iroponera, Schmidt & Shattuck, 2014

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 : 196-198

Iroponera gen. nov.

Fig. 46

Type-species: Iroponera odax (described below); by present designation.

Iroponera is a monotypic genus restricted to south-eastern Australia. It occurs in wet forested habitats and is infrequently encountered.

Etymology. The name Iroponera is based on the Latin ironia, “assumed ignorance”, combined with the suffix “-ponera”, derived from the subfamily name Ponerinae . The name expresses our surprise at finding such a novel genus in a well-collected country like Australia.

Diagnosis. Iroponera workers are recognizable by the presence of a single metabial spur, absence of eye (although small dimples or slight discolorations are sometimes present where the eyes would be expected) and elongate and narrow mandibles with three or four small, widely spaced teeth. In overall body shape and size Iroponera closely resembles Hypoponera or Ponera , and all of these genera share the single metatibial spur. However, the unique mandibular shape and lack of eyes will separate this genus from others in the subfamily.

Synoptic description. Worker. Small-sized (TL 2.6 mm) ants with the standard characters of Ponerini . Mandibles elongate and narrow, with three or four small, widely spaced teeth on the masticatory margin, the basal margin essentially absent, and lacking a basal groove or pit. Anterior clypeal margin broadly rounded and convex. Frontal lobes moderately large. Antennae often with a four segmented apical club. Eyes essentially absent, at most with small dimples or slight discolorations present where the eyes would be expected. Metanotal groove reduced to a suture. Propodeum broad dorsally. Propodeal spiracles round to oval. Metatibial spur formula (1p). Petiole nodiform. Helcium projecting from near midheight of anterior face of A3. Prora reduced and apparently absent. Girdling constriction between pre- and postsclerites of A4 apparent. Head, mesosoma and petiole weakly sculptured and with a matte surface, gaster weakly punctate. Head and body with scattered pilosity and a moderately dense pubescence. Color orange.

Queen. Not described.

Male. Not described.

Larva. Not described.

Geographic distribution. Iroponera is restricted to south-eastern Australia (southern New South Wales, Victoria and Tasmania) .

Ecology and behavior. This genus has been encountered only a handful of times and very little is known regarding its biology. All collections have been made at wetter sites consisting of wet sclerophyll woodlands. Nests occur in soil under rocks or under bark and contain only a few workers. The lack of eyes, small body size and pale color suggest a hypogeic lifestyle, and this may explain their infrequent collection.

Phylogenetic and taxonomic considerations. The placement of this genus within the Ponerinae has not been

examined in detail as the taxon was not included in Schmidt’s (2013) phylogeny. While superficially similar to Dolioponera , another tiny, eyeless, depigmented, slender ponerine with clubbed antennae and generally cryptobiotic habitus, this similarity is undoubtedly convergent. W. L. Brown (pers. comm.) speculated that Iroponera might be close to Cryptopone , but the lack of basal mandibular pits and mesotibial pusher setae, together with contrasting mesosomal shape and mandibular structure strongly suggest otherwise. In some ways, the Iroponera mandibles remind one of Myopias , but they are not as long and close differently, nearer to the clypeal margin. Determining the exact placement of this genus within the subfamily will require further data.

Figures

FIGURE 46. Worker caste of Iroponera odax: lateral and dorsal view of body and full-face view of head (holotype, MCZC); world distribution of Iroponera.