Among the various animals which display this distribution pattern are the leaf or pond turtles belonging to the genus Mauremys. Today there are six species, three with a distribution centred round the Mediterranean, and another three in Eastern Asia. Recent DNA work has shown that they are closely related to the Cuora I discussed in the last post, and the Asian genera Chinemys and Ocadia are part of the same group.
The rarest of the group is the species we have at Bristol, the Annam Leaf Turtle M.annamensis. The most southerly of the Asian species, it is found only in coastal lowlands in central Vietnam. Its closest relative is believed to be the Yellow Pond Turtle, M.mutica, which is found to the north in Vietnam and southern China.
|range of M.annamensis|
Mauremys are adapted to warm temperate and sub-tropical climates, and the western species are often exposed to very cold weather for at least part of the year. In common with other aquatic turtles, they hibernate underwater, only coming up on warm days. In the more seasonal parts of their range, where the ponds may dry up in the summer, they will also aestivate buried in the mud for part of the year.
As with most aquatic chelonians, they are omnivorous, feeding on aquatic insects, snails, worms and occasional fish, but also taking plant material. Mating takes place in the water, with the gravid females seeking out soft earth ear the water to lay a clutch of 4-8 eggs. As with most of not all chelonians, they have temperature-dependent sex determination, with egg incubation temperatures affecting whether the hatchling is male or female. In most species, the key temperature is around 30oC, but the exact temperature for M.annamensis is as far as I am aware not yet determined with certainty. Knowledge of this is however very important for conservation, as by incubating eggs at the correct temperature it is possible to maximise the number of egg-producing females and so maximise productivity in the captive population.
|Captive adult M.annamensis|
To return to our own animals – we currently have 6 juveniles bred at Chester Zoo on show. They are only a few years old, so it will be at least 3 or 4 years before they are large enough to produce offspring of their own. As M.annamensis is classed as Critically Endangered, this cannot happen soon enough.
(Images from European Freshwater Turtle Breeders Association, Wikipedia, Arkive)
The freshwater turtle genus Mauremys D.Barth 2003 http://vipersgarden.at/PDF_files/PDF-648.pdf
Declared Turtle Trade from the US – World Chelonia Trust