Nutphand, 1986
Southeast Asian narrow-headed softshell turtle
Recognition
This is one of the largest soft-shelled turtles, with a carapace as long and wide as 140 cm and 100 cm respectively (Nutphand, 1990). A large individual may weigh 100-120 kg. The carapace is light brown to yellowish-brown, with irregular pale yellow, dark-bordered, camouflage-like markings (number and shape vary between individuals), and a light rim. The plastron is cream-colored to pinkish-white. Five yellow stripes are present on the dorsal and lateral sides of the neck; two converge on the posterior neck, just before the carapace, to form a medial stripe that extends onto the surface of the head (the convergence occurs on the back of the head in C. indica). The skin is a tan to brown, the front limbs bear some vague yellow bands on brown, and the hindlimbs are unmarked.
Adult males have longer, thicker tails than adult females and juveniles.
Distribution
Chitra chitra is known only from the Mae Khlong River in Ratburi Province and the Khwae Noi River in Kanchanaburi Province, western Thailand (Nutphand, 1990).
Geographic Variation
Unknown.
Habitat
A riverine species, it prefers clean, flowing rivers with sandy bottoms (Nutphand, 1979). The natural habitat has been much altered by dams and reservoirs. All confirmed specimens have been captured either in the reservoirs or in the densely settled downstream river sections (Van Dijk and Thirakhupt, 1996).
Natural History
This species seldom ventures on land, possibly only to nest. According to Nutphand (1986), Chitra chitra deposits its eggs before the rainy season in nest cavities 50-75 cm deep above the upper water level in the sand or a mixture of sand and soil on the banks of its rivers. A clutch may contain 60-117 eggs (Nutphand, 1979, 1986). Nutphand (1986) reported a 111 cm female released 107 eggs. The eggs are white, round, hard-shelled, and have a diameter of about 35 mm.
Chitra chitra eats clams, crabs, and fish; to catch fish, it rapidly shoots out its long neck and seizes the fish with its mouth as the fish swims by (Nutphand, 1986). Taylor (1970) commented on the severity of bites by large individuals, but Peter Paul van Dijk (pers. comm.) suspects that Taylor saw a closed-mouth lunge and interpreted it as a vicious attempted bite. The jaws of Chitra are so slender and delicate that biting seems out of the question.
Remark
The original description by Nutphand (1986) and a subsequent one published by Nutphand in 1990 are very brief, and lack the detail usually expected in a species description. Fortunately, Van Dijk, Thirakhupt, and Webb (in press) have re-evaluated Chitra chitra, and have prepared a more detailed description and comparison with C. indica and Pelochelys cantorii.
IUCN Red List Status (1996)
The species is Critically endangered (A1cd, B1+2c) and its population declining (Baillie and Groombridge, 1996; Van Dijk and Thirakhupt, 1996). In addition to alteration of its waterways, other threats to the continued existence of C. chitra include pet trade collecting (this animal does badly in captivity; Van Dijk and Thirakhupt, 1996), and collection of both adults and eggs for the food market. The turtle needs to be protected under Appendix 1 of CITES, and hunting of food and the pet trade must cease, while formation of protected areas within its range must continue.