Family Pyxicephalidae

Tomopterna Duméril and Bibron, 1841

sand frogs, pyxies, sandpaddas (A)

By A. Channing

Currently accepted name: Tomopterna indet.
Red listing status:

Description

The generic name is derived from the Greek: tomus = cut; pterna = heel. This refers to the deep groove beneath the flange-like metatarsal tubercle projecting from the heel.

Tomopterna contains robust-bodied, medium-sized burrowing frogs that have a rather toad-like appearance and gait (Passmore and Carruthers 1995). The dorsal colouration is usually a mottled grey or brown. The metatarsal tubercle is large and flange-like and is used in digging. Two other genera of stout, burrowing ranids in the atlas region, Hildebrandtia and Pyxicephalus, can be distinguished from Tomopterna by the presence of longitudinal markings on the throat of the former and tooth-like processes in the lower jaw of the latter.

Distribution

The eight species in this genus are widely distributed in East, Central and southern Africa, and include a cryptic polyploid species, T. tandyi (Bogart and Tandy 1976; Channing and Bogart 1996). Additional polyploid species await description (Dawood et al. 2002). These can be reliably identified only on the basis of advertisement calls or DNA sequences.

This genus occurs throughout the atlas region and two or more species may occur in sympatry in many areas. The distribution maps are a reasonably accurate representation of the distribution of most of the Tomopterna species, as presently defined, that occur in the atlas region. However, these distribution patterns may change with the identification of additional cryptic species.

Habitat

Tomopterna species inhabit all biomes in the atlas region with the exception of forests and extremely arid habitats. They are found at altitudes ranging from sea level to 2000 m. They are associated with sandy soils, and are often found along seasonal river courses and temporary pans, and also commonly frequent earth-walled dams on farms and in towns.

Life history

These frogs aestivate underground during the dry season and emerge with the onset of rains. Calling takes place near the edge of shallow water, usually in open areas bare of vegetation. The dorsal colouration camouflages these frogs perfectly against a background of sand and pebbles.

After the eggs have been laid, they sink to the bottom of the water. The tadpoles are brown, robust and large, reaching 44 mm in length in T. delalandii. They are benthic, but often feed upside down at the water’s surface (Channing 2001).

The adults feed on a range of arthropods. Known predators of adults include the Hamerkop Scopus umbretta, Barn Owl Tyto alba and Brown House Snake Lamprophis fuliginosus. The tadpoles are preyed upon by terrapins, for example, Pelusios spp., Pelomedusa subrufa, and fishing spiders Thalassius spp.

Conservation

The known species of Tomopterna are widely distributed and relatively abundant. They occur in numerous protected areas and are not threatened. However, the identification of further cryptic species may necessitate the re-evaluation of their conservation status.