Size Adult females may attain a body length of 95 mm but males are smaller.
Description This is one of the larger sized toads and has the typical square, thick-set build associated with this genus. The skin is rough and dry with wart-like glandular elevations (which are rounded) on the upper side, and includes a pair of massive parotoid glands on the neck behind the eyes. The eye (which is often greenish) has a horizontally elliptical pupil. The legs are longer than the body length. There are no hard ridges on the heel of the hindfoot, nor discs on the toes and fingers, nor are the toes fringed with webbing. The tarsal fold is well developed. Generally, the upper body surface is either uniformly light brown or brown with distinctive dark blotches, and these blotches merge in some populations. The underside is off-white and often covered with small spots, particularly in young specimens. The advertisement call is a series of rasping squawks emitted at a rate of about one per second.
Biology The Karoo toad mainly inhabits the summer rainfall region but its habitat also enters the winter rainfall region. It is well adapted to survive in arid areas and occurs in a variety of habitats ranging from flat, open sandy areas to rocky mountainous areas in the Nama-Karoo, Succulent Karoo, Fynbos, Thicket and Grassland biomes. Breeding occurs in a variety of permanent or temporary water bodies such as streams, rivers, dams, pans, bogs, water holes and rain pools.
Breeding has been recorded during the summer period from spring to autumn and in winter in the winter rainfall region. However, this species is an opportunistic breeder in the winter rainfall region, and will also breed during the summer months if there is sufficient water available. At breeding sites, the males call after dark but may also call during the day, especially in overcast and wet weather. They have also been found to be well separated from other calling males. The eggs, which are 1.5 mm in diameter, are laid in long, 7 mm wide strings and may number over 100 eggs per clutch. These are laid in shallow water and become attached to vegetation or any other object in the water. The eggs develop into free-swimming benthic tadpoles which are relatively small and dark, and tend to form small schools. They are known to grow to a maximum length of 24 mm within a matter of days and take about 20 days to metamorphose into tiny toadlets. The Karoo toad usually runs or walks but can hop for short distances.
Distribution This species has a wide distribution in the drier western parts of South Africa which extends into some of the eastern parts of the country and includes Lesotho and Swaziland . There are also a few records from southern Namibia and Zimbabwe has an isolated population. The taxonomy of this species requires further investigation which could possibly result in some populations being described as separate species.
Distribution in GCBC The Karoo toad occurs in the lower lying areas to the west of the main Cederberg range of mountains, and in the lowlands that extend from the coastal zone inland in the northern part of the GCBC.
Conservation status Not threatened.
Threats No serious threats.
Current studies This species was assessed in the Southern African Frog Atlas Project (published in 2004).