Family Pyxicephalidae

Strongylopus Tschudi, 1838

stream frogs, langtoonpaddas (A)

By A. Channing

Currently accepted name: Strongylopus sp.
Red listing status:

Description

The genus name is derived from the Greek: strongylos = rounded (in cross section); pus = foot. Strongylopus species are medium sized, 30–50 mm in length, and most have a streamlined body with long legs and a pointed snout. From a distance they resemble the young of Afrana species, but on closer inspection may be distinguished from other ranid frogs by their long foot that is at least as long as the distance between the tympanum and the tip of the urostyle. The toes are typically very long and moderately to weakly webbed (cf. Afrana and Ptychadena in which the webbing is well developed; Poynton and Broadley 1985b). The dominant colour patterns include stripes, spots and blotches on a brown background. Often a dark band passes from the nostrils, through the eye to the tympanum.

Distribution

The genus Strongylopus contains nine described species that are found from northern Tanzania to the southern tip of Africa. Of these, five are endemic to the atlas region. S. springbokensis occurs in the arid west while the remainder are distributed through the wetter eastern and southern parts of the atlas region. Most species are cryptic, but the advertisement calls are loud and easy to identify. The atlas data for this genus are reliable but incomplete for some species.

Habitat

Members of this genus inhabit all biomes and occur in a wide variety of vegetation types. Some species are found in grassland and forest at high altitudes and on steep slopes, while others occur in flat, low-lying areas. S. grayii is a generalist that can survive in disturbed areas and is able to live and breed even in ditches and rubbish tips. The breeding habitat varies from springs in the arid Richtersveld, to temporary pools in savanna, to streams running through forests.

Life history

Most species commence calling at the beginning of the rains. S. grayii and S. bonaespei, however, start to call with the onset of cold weather in the winter-rainfall region. Most species lay eggs out of water, and these develop into tadpoles within the egg capsule. When the egg mass is flooded by rising water, the tadpoles escape from the capsules. Eggs have thick membranes and are able to survive for more than six weeks without water, provided that they are in a cool, damp place. There are few records of predators (see species accounts).

Conservation

Two species are of concern: S. springbokensis is classified Vulnerable and S. wageri Near Threatened (see species accounts). Both species have limited areas of occurrence and occupancy and are threatened by continuing habitat loss. The low level of importance assigned to frog species by various governing bodies can be a serious threat. For example, the type locality of S. springbokensis was converted to a duck pond by the local authorities, despite their being informed of the presence of the species by Cape Nature Conservation. All species in the atlas region occur in at least one protected area.