Dolioponera Brown

Dolioponera Brown

Fig. 36

Dolioponera Brown, 1974a: 31 (as genus in Ponerinae, Ponerini). Type-species: Dolioponera fustigera Brown, 1974b: 32; by original designation.

Dolioponera is a monotypic genus known from only a few specimens collected in west and central Africa. They are apparently cryptobiotic, but nothing else is known about their habits.

Diagnosis. Dolioponera are among the most morphologically distinctive of all ponerines. Their long sinuous bodies are unmistakable, and their unusual setose mandibular teeth are also autapomorphic. Other diagnostic characters (in combination) include their blunt anteromedial clypeal projection, laterally expanded triangular frontal lobes, tiny or absent eyes, clubbed antennae, fusion of mesopleuron with the mesonotum, and relatively high helcium.

Synoptic description. Worker. Very small (TL 2.2–2.8 mm) and very slender ants with the standard characters of Ponerini. Mandibles triangular, with a rounded basal angle, a basal groove, and a series of unusual teeth on the inner surface which appear to be modified setae. Anterior margin of clypeus with a short blunt medial projection. Frontal lobes moderately expanded laterally, with broadly triangular lateral margins. Apical antennal segment enlarged. Eyes absent to very small. Mesopleuron apparently fused to the mesonotum. Metanotal groove absent. Propodeum broad dorsally. Propodeal spiracle round. Metatibial spur formula (1p). Petiole nodiform, the node long and cylindrical. Helcium projecting from near midheight on the anterior surface of A3. Gaster with a strong girdling constriction between pre- and postsclerites of A4. A4 long and cylindrical. Head and body densely punctate, with only sparse pilosity but a dense pubescence. Color orange.

Queen. Similar to worker except eyes present and conspicuous, moderately large and well in front of midlength of head capsule (maximum length of eye about equal to maximum width of scape; much larger than in the specimens reported by Fisher (2006)); large ocelli present. Mesosoma considerably more voluminous than in worker, and with a full complement of flight sclerites.

Male. Unknown.

Larva. Undescribed.

Geographic distribution. Dolioponera is known from only a few collections in Cameroon, Central African Republic and Gabon (Fisher, 2006), Ivory Coast (B. Bolton, pers. comm.) and from a single record from Yemen (Collingwood & van Harten, 2005). The true extent of its range is uncertain.

Ecology and behavior. Virtually nothing is known about the habits of Dolioponera. All known specimens were collected from soil or leaf litter, and their morphological characteristics strongly suggest a cryptobiotic lifestyle. Their tiny body size and unusual sinuous body form suggest that they inhabit and forage in very tight spaces, and their strange mandibular dentition and medial clypeal projection suggest that they are specialist predators, though the identity of their prey is unknown.

Phylogenetic and taxonomic considerations. Brown (1974a) described Dolioponera based on a single specimen from Gabon, and since then a few additional specimens have been collected (Fisher, 2006). The phylogenetic position of Dolioponera is unclear, as molecular data are lacking and morphological evidence is ambiguous. Bolton & Brown (2002), Fisher (2006), and Bolton & Fisher (2008c) suggest the possibility of a close relationship between Dolioponera and the Plectroctena genus group (sensu Bolton & Brown, 2002). We agree that this is the most probable phylogenetic placement for Dolioponera, and have therefore included Dolioponera within the Plectroctena group. See the earlier discussion of phylogenetic relationships within the Plectroctena group for more on the possible phylogenetic position of Dolioponera.