Family Pyxicephalidae

Afrana vandijki Visser and Channing, 1997

Van Dijk’s River Frog, Van Dijk se Rivierpadda (A)

By A. Channing

Currently accepted name: Amietia vandijki (Visser and Channing, 1997)
Red listing status: Least Concern (2013)

Photo by Grundlingh Felicity, 2003. URL: FrogMAP: 898

RED LIST SPECIES

Status: Data Deficient (DD)

Identification

This species reaches a body length of 54 mm in males and 56 mm in females. A. vandijki is superficially similar to the sympatric A. fuscigula, and the two species are known to breed in the same pools. This should be borne in mind when identifying specimens from areas in which the species coexist. A. vandijki may be distinguished from A. fuscigula by the presence of a large pale mark in the middle of the back, and a prominent skin fold running from the back of the eye to the arm, obscuring the upper or entire tympanum. In A. vandijki, 2–3 phalanges of the fourth toe are free of webbing, whereas in A. fuscigula only half to one phalanx is free of webbing (Visser and Channing 1997).

The call is biphasic, consisting of a series of 10–15 clicks uttered within 0.8 s, followed by a harsh, pulsed croak about 0.25 s in duration (Channing 2001).

The tadpoles reach about 55 mm in length. They are dark brown or velvety black with deep, dark fins and a paddle-like tail. The tadpoles are easily distinguished from those of A. fuscigula, which have only a small amount of pigment in their tails (Channing 2001).

Distribution

A. vandijki occurs at medium to high altitudes in the Swartberg and Langeberg mountain ranges in the east of the Western Cape Province. Despite the addition of a number of new atlas records, the distribution of this recently described endemic species is not well known. The atlas data are accurate but incomplete.

Habitat

This species inhabits Mountain Fynbos that receives annual rainfall of 300–800 mm, mainly in winter. The frog is associated with rocky streams on steep, well-vegetated slopes and forested gorges (Visser and Channing 1997). Breeding habitat includes pools on the sides of streams, and deeper, slow-flowing water.

Life history

This species is active throughout the year. Breeding takes place October–December, after good rain. Little is known of the species’ breeding biology. Predators and food items have not been recorded.

Conservation

Status

A. vandijki is classified Data Deficient (Harrison et al. 2001; this publication). It is known to occur in Grootvadersbos Nature Reserve, Boosmansbos Wilderness Area, Swartberg Nature Reserve and Garcia State Forest (Harrison et al. 2001).

Threats

Present and predicted threats include damming of streams, wildfires and loss of habitat to invasive alien plants (Harrison et al. 2001).

Recommended conservation actions

Fieldwork is needed to collect additional distribution data and details of the life history of A. vandijki. The degree of genetic differentiation between the Swartberg and Langeberg subpopulations needs to be established. Habitat should be managed to ameliorate existing and predicted threats (Harrison et al. 2001).

Current distribution map

Undated records;  pre-1996;  1996 to 2002;  2003 to present