Gray, 1864a
Cantor's giant softshell turtle
Recognition
This is the largest of the trionychid turtles, reaching a carapace length of up to 200 cm (Das, 1991). The smooth adult carapace is mostly uniform olive to brown with no definite pattern. The neck and limbs are similarly pigmented. Tubercles are missing from the cervical region, or are very small. Small juveniles may have dark spotted carapaces with a yellow rim and dark spots on the head; the carapace and head markings are lost with age. The young lack pliable tubercles on the neck. The juvenile carapace is smooth, or with continuous ridges only in the area of the underlying bones. Vertical cusp-edged scales are present along the lower margin of the forelimb.
Distribution
Pelochelys cantorii lives in southeastern Asia from India to southern China (including Hainan) south through Thailand and Vietnam into Malaysia, western Indonesia (including Java and Borneo), the Philippines, and northern New Guinea (Rhodin et al., 1993; Webb, 1995).
Geographic Variation
It is possible that P. cantorii as now recognized consists of several different taxa. Robert G. Webb has informed us that the northern New Guinea population most probably represents a distinct species. Smith (1931) reported that all specimens he examined from Myanmar, Thailand, and the Philippine Islands had seven neurals and the last two pairs of costals touching medially, while those from Malaysia, Indonesia, and New Guinea had eight neurals and only the last pair of costals touching medially. Baur (1891), on the basis of skull features, thought specimens of Pelochelys from the Philippines differed from mainland specimens. A good quantitative study is needed to determine if subspecies do exist; unfortunately, because of its large size relatively few specimens have been deposited in museum collections. The names P. cummingii Gray, 1964a and P. poljakowii Strauch, 1890 are available from the Philippines and southern China, respectively, should these populations prove to be different taxa. The subfossil turtle P. taihuensis Zhang, 1984 from Zhejiang Province, China was put in the synonymy of Rafetus swinhoei by Zhao and Adler (1993).
Habitat
Pelochelys cantorii is found in freshwater streams and deep, slow-moving rivers, often far inland. It commonly enters brackish estuaries along the coast and has been caught at sea. Much time is spent under water, and Nutphand (1979) reported it can absorb needed oxygen through its pharynx.
Natural History
Dr. Edward Moll has told us that Malaysian P. cantorii nest in February and March, laying 24-28 eggs per clutch. In India it lays clutches of 20-28 eggs in February and March; the spherical eggs are 30-35 mm in diameter (Das, 1985, 1995).
Pelochelys cantorii eats fish, crabs, shrimp, mollusks, and some aquatic plants (Nutphand, 1979).
Remark
After designation of a neotype and restricting the name Pelochelys bibroni to the population in southern New Guinea, Webb (1995) chose the name Pelochelys cantorii Gray, 1864a by line priority over P. cummingii Gray, 1864a for the remaining Asian and northern New Guinea populations. Also, the type locality of P. cantorii is in Malaysia, while that of P. cummingii is in the Philippines, and possibly the Philippine giant softshells represent a different taxon.
IUCN Red List Status (1996)
Vulnerable (A1cd+A2cd).