Austroponera, 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 : 180-182

Austroponera gen. nov.

Fig. 41

Type-species: Euponera (Brachyponera) rufonigra Clark, 1934b: 30 ; by present designation.

Austroponera is a small genus (3 described species) which is restricted to Australia and New Zealand. While it is found in a variety of habitats it is nowhere common and is biologically little known.

Etymology. Austroponera is a combination of austro, Latin for “south” and referring to Australia, the region where this genus occurs, together with “ponera” from the subfamily name Ponerinae .

Diagnosis. Workers of this genus can be separated from other Ponerinae by the combination of the following characters: anterior clypeal margin convex, without a blunt anteromedial rectangular projection and in side view posterior to the anterior margin of head (the clypeus rounded above mandibles), mandibles triangular and relatively short, their outer margins generally flat or convex medially and lacking a basal pit or groove, the ventral apex of the metatibia with both a large pectinate spur and a smaller simple spur, the propodeal spiracle round or ovoid, and a prora present on the anterior margin of the first gastral sternite. Austroponera is morphologically similar to several other ponerine genera. These include Brachyponera , from which it can be separated by the lack of a basal mandibular pit or groove and the presence of a prora on the anterior margin of first gastral sternite; Cryptopone , which has stout traction setae on the dorsum of the mesotibiae (these are absent in Austroponera ); Pseudoponera , which has a slit-shaped rather than round propodeal spiracle as found in Austroponera ; and Rasopone , from which it can be separated by its presence of a stridulatory organ on A4 and its rounded rather than angular anterior clypeal margin. While not closely related based on the findings of Schmidt (2013), Austroponera is morphologically similar to some Mesoponera species. It differs in the shape of the clypeus (in side view the anterior clypeal margin is posterior to the anterior margin of the head, the clypeus being rounded above mandibles) and in having shorter mandibles which have their outer margins generally flat or convex medially rather than concave. While these two genera are superficially similar and the differences outlined here subtle, they are not closely related and the similarities are due to convergence rather than relatedness.

Synoptic description. Worker. Medium-sized (TL 4–5 mm) ants with the standard characters of Ponerini . Mandibles triangular, relatively short, with roughly ten teeth and no basal pit or groove. Anterior margin of clypeus broadly convex and often with a small projecting tooth medially. Frontal lobes small. Scapes not flattened basally. Eyes moderate in size, located anterior of head midline. Mesopleuron divided by a transverse groove. Metanotal groove either shallowly depressed or reduced to a suture. Propodeum dorsally broad, not narrowed anteriorly. Propodeal spiracle round. Metatibial spur formula (1s, 1p). Petiole squamiform. Subpetiolar process lacking an anterior fenestra. Helcium low on anterior face of A3. Girdling constriction between pre- and postsclerites of A4 apparent. Stridulitrum present on pretergite of A4. Head and body with scattered pilosity. Color reddish-brown to dark brown.

Queen. Similar to worker, but winged or ergatoid and with the other differences typical for alate ponerine queens.

Male. Unknown.

Larva. Unknown.

Geographic distribution. Austroponera is restricted to Australia and New Zealand

Ecology and behavior. Species of Austroponera are found in a diversity of habitats ranging from open situations such as roadsides, pastures and gardens to native forests ( Don, 2008; Heterick, 2009). Nests are small, with tens rather than hundreds of workers, and are found in rotting wood, leaf litter, under rocks, or directly in the soil ( Brown, 1958). They are predacious and attracted to sweet baits. Workers are often encountered in leaf litter samples and pitfall traps and when disturbed are timid, retreating into their nests ( Don, 2008). Both winged (in A. castaneicolor ) and ergatoid (in A. castanea ) queens are known to occur in the genus ( Wilson & Taylor, 1967).

Phylogenetic and taxonomic considerations. Schmidt (2013) included A. castanea in his phylogeny and found it to be the sister group of Pseudoponera , with this pair, in turn, the sister group to Cryptopone . The species currently included in Austroponera show significant variation in a number of morphological characters. For example, the Australian species A. rufoniger differs from the remaining species, which are both restricted to New

Zealand, in lacking the medial clypeal tooth and well developed metanotal groove. As only one of the New Zealand species was included in Schmidt’s (2013) phylogeny there is limited detailed information on its relationship to the Australian species. Given the morphological differences between these species it is possible that the genus is not monophyletic. However at this time we are placing them together based on the morphological characters outlined above, along with biogeographic considerations, while noting that this conclusion may need to be modified when the results of further studies are known.

Austroponera is morphologically similar to Rasopone , a genus known only from Central and South America. They share a similar body habitus and differ primarily in Austroponera possessing a stridulatory organ on A4 and in having a differently configured clypeus. Based strictly on morphology, it could be argued that they should be placed together in a single genus. However, we are keeping them separate based on the characters outlined above and biogeographic considerations ( Austroponera is restricted to the Australian region while Rasopone is only known from the Americas). Unfortunately no species of Rasopone were included in Schmidt’s (2013) phylogenetic analysis and the phylogenetic relationship between these two genera is uncertain. A detailed study of the relationships among the species currently placed in these genera would be highly advisable.

Figures

FIGURE 41. Worker caste of Austroponera castanea: lateral and dorsal view of body and full-face view of head (CASENT0172341, April Nobile and www.antweb.org); world distribution of Austroponera.