Family : PLATYSTERNIDAE
Species : Platysternon megacephalum
Maximum carapace length : 25 cm
(Chan-ard et al, 2012)

The endangered Big-headed Turtle inhabits hill and mountain streams and small rivers in northern areas of mainland Southeast Asia.

This is the only living species in the family Platysternidae. The taxonomic, or evolutionary, placement of this family relative to other turtle families such as Testudinidae (land tortoises), Geoemydidae (Asian hard-shelled terrapins) and Emydidae (new world terrapins) is unclear.

'Platysternon' means 'flat-chested' (which must refer to the underside of the plastron), and 'megacephalum' means 'large-headed'.

The identifying features of this small-medium terrapin are the large head, which cannot be withdrawn into the shell, and the long, thick tail (which in juveniles may exceed carapace length). The latter is highly muscular, and is used to help the turtle push itself over obstacles.

The shell is oval and flattened, with a prominent vertebral keel. The jaws are markedly hooked and, reportedly, this turtle can use its 'beak' to help it climb into trees (Das, 2010).

The carapace and plastron are brownish, yellowish, greenish or greyish (Pipatsawasdikul et al, 2010). Juveniles have more vivid colours, with bright red skin on the cheeks and throat, and a yellow stripe behind the eye.

It is nocturnal, and its diet comprises small invertebrates such as insects, snails and worms (Das, 2010).

It is heavily hunted and trapped: brightly-coloured juveniles end up in the international pet trade, and adults end up in food markets in various countries.

This turtle is known to occur above 700 metres in southern Myanmar, northern Thailand, Laos and Cambodia (?). In other locations, such as Vietnam and parts of southern China it occurs at lower elevations (Chan-ard et al, 2012).

Reptile Database currently lists 5 valid subspecies. 

Figs 1 to 3 : Juvenile, with a carapace length of 8.2 cm, from Doi Suthep, Chiang Mai province, northern Thailand. At the same location were tadpoles of a species of Leptobrachium. It was postulated that the turtles might prey on these tadpoles (Manthey & Denzer, 2013). Photos thanks to Ulrich Manthey.


References :

Chan-ard, T., Cota, M., Achachak, C., & Safuwong, M. (2012). Measurements of the Big-Headed Turtle (Platysternon megacephalum Gray, 1831)(Platysternidae, Testudines) from Phu Luang, Loei Province, Northeastern Thailand.

Manthey, U. & Denzer, W. (2013). Südostasiatische Anuren im Fokus: Spezies der Gattung Leptobrachium Tschudi, 1838 (Amphibia: Anura: Megophryidae). Sauria, 35(3), 3-22.

Pipatsawasdikul, K., Voris, H. K., & Thirakhupt, K. (2010). Distribution of the Big-Headed Turtle (Platysternon megacephalum, Gray 1831) in Thailand. Zoological Studies, 49(5), 640-650.

Conservation of Asian Tortoises & Freshwater Turtles: pdf