(Smith, 1838)
East African serrated mud turtle
Recognition
Pelusios sinuatus is a large (to 46.5 cm) Pelusios with an elongated oval carapace that is strongly serrated posteriorly in juveniles, less so in adults. Broadest behind the bridge, the carapace is flattened or concave across the vertebrals in adults. All vertebrals are strongly keeled in juveniles, less so in adults. In adults the keel is reduced to raised protuberances at the rear of the first four vertebrals. Vertebrals are broader than long in juveniles, usually longer than broad or of equal dimensions in adults. Four to seven neurals are present, with six or seven the usual number; the 8th is always absent, the 7th is reduced or absent, the 5th may be absent, and the 1st is reduced and does not touch the nuchal. Growth annuli and radiations are often present on the carapacial scutes, giving the shell a roughened appearance in juveniles and young adults. The carapace is black, but the seams may be yellow in adults; juveniles have brown to olive carapaces. The plastron is large, only slightly smaller than the opening of the carapace, and bears a deep posterior notch. Its anterior lobe is short, less than twice as long as the interabdominal seam, and the posterior lobe is not indented at the abdominal-femoral seam. The plastron formula is: abd > fem > intergul >< an > hum > gul >< pect. The intergular scute is usually about twice as long as broad. A small axillary scute is present on the broad bridge. The bridge and the undersides of the marginals are black; the plastron is yellow with a black border. A yellow streak extends backward on each anal scute. The head is broad, but not overly long, with a protruding pointed snout and notched, often bicuspid, upper jaw. A large frontal scute covers much of the dorsal surface of the head. Two barbels are present on the chin. Dorsally, the head is yellowish gray to olive, sometimes with small darker markings. Chin, throat, and underside of the neck are yellow, and the limbs, tail, and dorsal surface of the neck grayish.
The karyotype consists of 34 chromosomes (Bull and Legler, 1980).
Males have longer, thicker tails and slightly concave plastra.
Distribution
Pelusios sinuatus lives solely in East Africa where it ranges from southern Somalia southward to Zululand, much of the former Transvaal Province, and Kwazulu-Natal, and westward to Lake Tanganyika and Victoria Falls.
Habitat
Pelusios sinuatus occurs only in permanent bodies of water, such as rivers and lakes, which are found from the coastal plain to elevations of over 1500 m in the upland savannah (Loveridge, 1941) (Pelusios sinuatus biotope).
Natural History
Loveridge (1941) reported native fishermen told him that Pelusios sinuatus nests in July, but he questioned this since very small individuals (51 mm) were collected in March and July, indicating a very long developmental period. Ewert (1979) described the eggs as elongated with a parchmentlike shell and a long vitelline sac. Loveridge (1941) described the plastron in the very young as brick-red edged with black, the scute seams being broadly edged with white.
In the wild, P. sinuatus feeds on worms, insects, snails, fish, and frogs.
IUCN Red List Status (1996)
Not listed.