Skeleton of Indian Flapshell Turtle
Species: L. punctata
The skull has vomer-prefrontal struts, the postorbital arch narrower than the horizontal diameter of the orbit, a closed fenestra postotica (broad ascending strut of pterygoid sutured to opisthotic), and a short maxillary bridge (between the foramen intermaxillaris and the opening of internal nares). The body of the hyoid consists of three pairs of bones and the posterior horn is not subdivided. The carapace has a prenuchal bone (initially isolated but sutured to the nuchal in large adults), two neurals between the first pair of pleurals, and a diagonally oriented suture between the nuchal and the first pleural (forming laterally expanded first pleurals). The nuchal (ventral view) is bifid or notched on either side (costiform processes). There are six to nine (usually eight) neurals with one or two pairs of the posteriormost pleurals sutured medially; the last (eighth) pair of pleurals is subtriangular in shape. The rear half of the bony carapace has posteriorly tapered and somewhat concave lateral margins. There is a series of juxtaposed but unsutured peripheral elements, the anteriormost being the largest, that are not connected to the ribs or to the rest of the carapace, and that may or may not be homologous with the peripherals of hardshelled turtle species. The number of peripherals seems to vary ontogenetically, with the smallest number in the largest turtles, the reduction presumably occurring by fusion between adjacent elements. The plastron has well developed callosities on all bones, except that the isolated entoplastral callosity varies greatly in size, and may be absent. The hyo- and hypoplastra are fused on each side, without visible suture, and share a very large callosity that, in large adults, is enlarged anteriorly and almost contacts the posterolateral enlargement of the epiplastral callosity to form the lateral margin of the carapace; thus, replacing the peripheral bones in this area of the shell.
About the animal
The Indian flapshell turtle (Lissemys punctata) is a freshwater species of turtle found in South Asia. The “flap-shelled” name stems from the presence of femoral flaps located on the plastron. These flaps of skin cover the limbs when they retract into the shell. It is unclear what protection the flaps offer against predators. The carapace of L. punctata viewed from above is broadly oval in adults, but more circular in young, widest just anterior to hind limbs. The carapace is moderately arched, shell height is 35.0-40.5% of carapace length, the margin of the carapace is smooth and slightly flared posteriorly, the marginal bones are not united with the pleurals, the plastron is large but mostly cartilaginous. Indian flapshell turtles are widespread and common in the South Asian provinces.