Streblognathus Mayr

Robertson, H. G., 2002, Revision of the ant genus Streblognathus (Hymenoptera: Formicidae: Ponerinae)., Zootaxa 97, pp. 1-16 : 1-2

[[ Genus Streblognathus Mayr ]]

Streblognathus was named by Mayr (1862) to hold a single species Streblognathus aethiopicus , originally described as Ponera aethiopica by Smith (1858). Distribution of the genus is limited to grassland and southern karoo regions of southern Africa, and it has the largest worker ants in Africa, measuring up to 2.5 cm long. Like many large southern African ponerine ants, Streblognathus has lost the queen caste and instead, reproduction is undertaken by a single, mated worker, termed a gamergate (Ware et al. 1990; Peeters 1991). Mandibular glands of workers contain three types of pyrazines which, in a study based on two colonies, were found to occur in smaller quantities and in different proportions in the gamergate compared with the mated workers (Jones et al. 1998). Colony size of S. aethiopicus is moderately small ranging from 9 to 51 workers (Ware et al. 1990). Workers stridulate, apparently for alarm purposes, by moving the presclerite of the second gastral segment, which has ridges on it, against the posterior edge of the first gastral segment (Lewis 1896, Ware 1994).

Carpenter (1930) drew attention to the apparent similarity between Streblognathus , Dinoponera Roger (South American genus), and Archiponera Carpenter (an extinct genus known from fossils in the 35 million year old Florissant Shales in Colorado, USA). Kempf (1971) commented that Dinoponera was clearly related to Pachycondyla F. Smith and other large-sized ponerine allies. The above genera fall in the tribe Ponerini (Bolton 1995), and although there is an admitted similarity between them in the general habitus of workers and males, no-one has found dependable morphological characters that can be used to discern their evolutionary relationships. The situation is further confused by the considerable morphological variation in Pachycondyla and the high probability that it is paraphyletic or polyphyletic.

This revision of Streblognathus came about because of the discernment of a new species, specimens of which were previously included under S. aethiopicus . Behavioural and molecular research by V. Cuvillier-Hot, C. Peeters and co-workers (submitted) has revealed that there are two species in the genus and this is further confirmed by detailed morphological analysis, the results of which are presented here.