(Lacepède, 1788)
East African black mud turtle
Recognition
This is a moderate-sized (to 20 cm) Pelusios with an elongated, oval, unkeeled, brown carapace that is unserrated posteriorly. In the adult, the vertebral scutes are all broader than long. Neural 1 touches the nuchal, but the 8th is separated from the suprapygal (occasionally it may be missing). The anterior plastral lobe is much broader than the posterior lobe; however, it is only slightly longer than the interabdominal seam (never more than twice as long). The posterior lobe is strongly constricted at the abdominal-femoral seam, and has an anal notch. The plastral formula is: abd > fem > intergul >< hum >< an > gul > pect. The intergular is about 1.5 times as long as broad. Axillary scutes are absent from the bridge. The plastron is yellow with dark seams or a dark border; the bridge is generally brown. A blunt, nonprotruding snout, an unnotched, nonbicuspid upper jaw, and two chin barbels occur on the large head. A short seam occurs between the frontal and temporal scales; a supralabial scale separating the postocular and masseteric scales is always present. The head is usually totally brown, but may contain some small black spots; the jaws are yellow. Neck, limbs, and tail are gray.
Keister and Childress (in Gorman, 1973) and Bull and Legler (1980) reported P. subniger has 34 chromosomes.
Males have longer, thicker tails and slightly concave plastra.
Distribution
Pelusios subniger is restricted to eastern Africa where it ranges from Burundi and Tanzania southward to Mozambique and westward to eastern Congo (former Zaire), Zambia, and northern Botswana; it also occurs on Madagascar, and the Seychelles (Broadley, 1981a). Introduced to Gloriosa Island (extinct), Mauritius Island (possibly extinct now), and Diego Garcia of the Chagos Archipelago (Bour, 1983).
Geographic Variation
Two subspecies are recognized. Pelusios subniger subniger (Lacepède, 1788), the East African black mud turtle, occurs in East Africa and on the islands of Gloriosa, Mauritius, and Madagascar. It has an entire (undivided) supraocular scale, little subdivision of the parietal scales, and an intergular scale that is not greatly enlarged. The Seychelles black mud turtle P. s. parietalis Bour, 1983 resides on the Seychelles Islands. Its supraocular and parietal scales are subdivided by numerous seams, and it has a very large intergular scale and correspondingly small gular scales.
Habitat
Pelusios subniger lives in swamps, marshes, lakes, rivers, and streams in the savannah over much of its range, but in southeastern Africa, Broadley (1981a) found it inhabiting pans and other temporary water bodies.
Natural History
Kaudern (1922) reported that a Madagascar female dug a flask-shaped nest cavity with her front legs and head (an obvious error), laid 12 eggs in an hour and then filled the nest. Broadley (1981a) reported a 17 cm captive female laid about 8 eggs during February and March.
The eggs are elliptical (36 x 21 mm) with a thin, leathery shell. Eggs incubated by Ewert (1979) at about 30°C hatched in 58 days. Loveridge (1941) reported the carapace length of a recent hatchling as 30 mm; Ewert (1979) stated the average carapace length of eight hatchlings was 34.9 mm.
Foods reported by Loveridge (1941) indicate that Pelusios subniger is omnivorous: grass, crabs, worms, snails, insects, fish, and frogs. Loveridge (1941) reported that these turtles are nocturnal, but they apparently bask and may wander about on land during the rainy season.
IUCN Red List Status (1996)
Not listed in Baillie and Groombridge (1996), but P. s. parietalis is considered Critically Endangered in Seychelles Red Data Book 1997 (Gerlach, 1997a) due to deterioration of its habitat. The Seychelles population size is reduced to 400-450 adults.