Pelochelys cantorii

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 thatof P. cummingii is in the Philippines, and possibly the Philippine giant softshells represent a different taxon.

IUCN Red List Status (1996)
Vulnerable (A1cd+A2cd).

Kingdom Animalia
Phylum Chordata
Class Reptilia
Subclass Anapsida
Order Testudines
Suborder Cryptodira
Superfamily Trionychoidea
Family Trionychidae
Subfamily Trionychinae
Genus Pelochelys
Species Pelochelys cantorii

Cantor's giant softshell turtle [English]

Trionyx géant de Cantor [Français]

Cantors Riesen-Weichschildkröte [Deutsch]

Cantors reuzenweekschildpad [Nederlands]

Baur, G. 1891. Notes on the trionychian genus Pelochelys. Ann. Mag. Natur. Hist. (London) (6)7: 445-446.

Das, I. 1985. Indian Turtles: A Field Guide. World Wildlife Fund—India Eastern Region, Calcutta. 119 pp.

Das, I. 1991. Colour guide to the turtles and tortoises of the Indian subcontinent. R&A, Publ. Avon, England. 133 pp.

Das, I. 1995. Turtles and tortoises of India. Oxford Univ. Press, Bombay. 179 pp.

Gray, J. E. 1864a. Revision of the species of Trionychidae found in Asia and Africa, with the descriptions of some new species. Proc. Zool. Soc. London 1864: 76-98.

Mell, R. 1929. Beiträge zur Fauna sinica. IV. Gründzuge einer Ökologie der chinesischen Reptilien und einer herpetologischen Tiergeographie Chinas. Berlin. 282 pp.

Moll, E. O., and J. Vijaya. 1986. Distributional records for some Indian turtles. J. Bombay Natur. Hist. Soc. 83: 57-62.

Nutphand, W. 1979. The Turtles of Thailand. Siamfarm Zool. Gard. 222 pp.

Pope, C. H. 1935. Natural history of Central Asia. Vol. 10. The reptiles of China. Amer. Mus. Natur. Hist. 604 pp.

Rhodin, A. G. J., R. A. Mittermeier, and P. M. Hall. 1993. Distribution, osteology, and natural history of the Asian giant softshell, Pelochelys bibroni, in Papua New Guinea. Chelonian Conserv. Biol. 1: 19-30.

Smith, M. A. 1931. The fauna of British India, including Ceylon and Burma. Reptilia and Amphibia, vol. 1, Loricata and Testudines. Taylor and Francis, London. 185 pp.

Strauch, A. 1890. Bemerkungen über die Schildkrötensammlung im Zoologischen Museum. Mem. Acad. St. Petersburg (7)38: 1-127.

Webb, R. G. 1995. Redescription and neotype designation of Pelochelys bibroni from southern New Guinea (Testudines: Trionychidae). Chelonian Conserv. Biol. 1: 301-310.

Zhang, M. 1984. A new species of Pelochelys from Zhejiang, with subfossil description. Acta Herpetol. Sinica (n. ser.) 3: 71-76.

Zhao, E, and K. Adler. 1993. Herpetology of China. Soc. Amphib. Reptiles, Oxford (Ohio), Contrib. Herpetol., vol. 10, plate 20.

Pelochelys cantorii
Pelochelys cantorii 2
Pelochelys cantorii 3 (close-up of head)
Pelochelys cantorii 4 (juvenile)