Family : TRIONYCHIDAE
Species : Pelodiscus spp.
Maximum carapace length : >35 cm (in P. maacki)

Pelodiscus turtles are a group of softshells whose distribution is centred in China and the Far East (refer to Fig. 6, Farkas et al, 2019 for species range).

As of 2020 five species are recognised, two of which occur in Southeast Asia, specifically Vietnam: Pelodiscus sinensis is the most wide-ranging of the two, occurring in northern Vietnam, China and parts of Japan. The other species, P. variegatus, occurs in north-central Vietnam, and on the island of Hainan, China.

Three other species occur in the Far East including P. axenaria (mainland China), P. parviformis (mainland China and Hainan) and P. maackii (China, Korea, Japan, Russia).

In their native habitat these turtles occur in still waterbodies such as ponds, lakes, marshes, and slow-flowing, lowland rivers. They are predominantly aquatic in habits, and are rarely seen out of water. Their natural diet comprises a wide range of aquatic invertebrates, fishes and vegetation.

The carapace, which may reach lengths of around 35 cm in P. maackii, is oval in shape. In adults the carapace is smooth in texture, whilst juveniles may possess raised tubercles. The neck is long and thick with leathery skin, and the snout is pointed. The carapace is olive green to brownish green in colour, and may be plain, mottled or patterned with small, pale spots depending on the species.

They are an important food source in some Asian cultures, and are extensively farmed. As a consequence they have  been introduced to many parts of Southeast Asia including Thailand, Peninsular Malaysia, Singapore, Indonesia and the Philippines. Hybridisation may have occurred between different species (Gong et al, 2018).

In Singapore Pelodiscus turtles are locally common in some man-made waterbodies, having been introduced or released from aquaculture stock. It is possible that hybrids may be present, which makes species identification difficult.

Fig 1 : A large Pelodiscus sp. with dark brown head from Singapore's central reservoirs, where Pelodiscus turtles have been widely introduced. The thin, dark, post-ocular stripe is a feature of both P. axenaria and P. parviformis (Table 4, Farkas et al, 2019). 

Figs 2 to 4 : Another Pelodiscus sp. from Singapore. This is the typical resting posture, with body and feet resting on the substrate and the neck extended to the water's surface. The abundant pale speckles on the carapace, limbs, head and neck, appear to be similar to those described for P. maacki (Table 4, Farkas et al, 2019).


References :

Farkas B, Ziegler T, Pham CT, Ong AV, Fritz U (2019) A new species of Pelodiscus from northeastern Indochina (Testudines, Trionychidae). ZooKeys 824: 71–86. https://doi.org/10.3897/zookeys.824.31376

Gong, S., Vamberger, M., Auer, M., Praschag, P., & Fritz, U. (2018). Millennium-old farm breeding of Chinese softshell turtles (Pelodiscus spp.) results in massive erosion of biodiversity. The Science of Nature, 105(5-6), 34.