(Boddaert, 1770)
Asiatic softshell turtle
Recognition
The round to oval carapace (to 83 cm) is olive gray to greenish brown with numerous yellow-bordered black spots and yellowish dots in younger individuals. In adults the yellow spotting tends to disappear; many adults show no pattern and have uniformly olive carapaces. Several longitudinal rows of small tubercles are on the juvenile carapace, but these disappear in very large adults, which have smooth carapaces. A series of enlarged tubercles lies on the anterior carapacial rim above the neck. No preneural bone is present, and only a single neural separates the anterior pair of costals. The 8th pair of costal bones is well-developed and meets at the midline. Carapacial bones are strongly pitted. Skin of the plastron is whitish to grayish in color. Five callosities may occur on the underlying bones, but that on the entoplastron is infrequent. The epiplastra touch or nearly touch, and the entoplastron lies at obtuse or right angles to the midline. The moderately sized skull has a bony snout which is much longer than the diameter of the orbit. A well-developed symphysial ridge occurs on the mandible, which is equal in length to the diameter of the orbit. No ridge occurs on the maxillary triturating surface. Head, neck, and limbs are olive with numerous small yellow spots, and slightly larger orange to pinkish blotches may occur on the sides of the head behind the orbit. These light spots fade with age leaving a network of dark lines on the adult's green head.
As with other softshells, the karyotype is 2n = 66 (Gorman, 1973).
Males have long, thick tails with the vent near the tip; the tails of females are short. Males have white plastra, females gray.
Distribution
Amyda cartilaginea ranges from the Gulf of Tonkin in Vietnam westward through Laos, Cambodia, and Thailand to southern Myanmar and southward through Malaysia to Sumatra, Java, and Borneo.
Geographic Variation
Variation exists in coloration, carapacial tuberculation and other superficial features (Peter Paul van Dijk, pers. comm.), but further study is required to determine if these variations are of taxonomic significance.
Habitat
Amyda cartilaginea is found in both upland streams and muddy, slow-flowing lowland streams and rivers, and also occurs in ponds, swamps, and oxbow lakes adjacent to large rivers.
Natural History
Nests are dug in mudbanks (Smith, 1931). Nutphand (1979) noted that in Thailand three or four clutches of eggs are laid each year; young females lay about 6 to 10 eggs per clutch and older, larger females lay 20 to 30 eggs. Moll (1979) reported the clutch size is 5 to 7, and Bourret (1941) stated a typical clutch is 4 to 8 eggs. The brittle-shelled eggs are spherical with diameters ranging from 21 to 33 mm, and the incubation period is long, 135 to 140 days (Bourret, 1941).
Amyda cartilaginea is described as highly carnivorous, feeding on fishes, amphibians, crustaceans, aquatic insects and other water-dwelling invertebrates, but a specimen obtained from a food market in Penang, Malaysia, had a large intestine packed with palm kernels (Davenport and Wong, 1992).
Nutphand (1979) reported that this softshell likes to come onto land to burrow into the sand and rest for long periods with only its snout showing. Our captives have seldom basked or come out of the water, although they spent much time buried beneath the sand under water; they also seemed highly nocturnal. A. cartilaginea has a fierce disposition and can be expected to bite when handled.
IUCN Red List Status (1996)
Vulnerable (A1cd+2cd).