(Gray, 1834a)
Malayan flat-shelled turtle
Recognition
The oval to elongated carapace (to 32 cm) is flattened dorsally and serrated posteriorly (more so in juveniles than in adults). A low, interrupted medial keel is present. Six or seven vertebral scutes are usually present; the first four and the most posterior are large and broader than long, but those between the 4th and last vertebral are smaller and may be as long as broad or a little longer than broad. Neurals are hexagonal in shape and shortest anteriorly. Carapacial color varies from greenish brown to yellowish brown or reddish brown, and each scute contains a dark spot or radiation. Juveniles have two dark spots on each vertebral and one on each pleural. The plastron is bound to the carapace by a ligament and, although there is a bridge, plastral buttresses are usually absent in adults. A poorly developed transverse hinge lies between the hyoplastron and hypoplastron in adults. The entoplastron is intersected by the humero-pectoral seam. The plastral formula is: abd >< pect > an > gul > hum > fem; and the anal scutes are not notched, or only slightly so, posteriorly. Plastron and bridge are yellow to orange with a large dark blotch on each scute, or almost entirely black. In the skull, the squamosal bone is probably present. Smith (1931) reported that the skull had a complete or incomplete temporal arch depending on the loss of the quadratojugal and postorbital. In several Asian genera, the squamosal (= quadratojugal) is either absent or subject to loss. McDowell (1964) found the squamosal in two skulls of Notochelys he examined, and was skeptical of reports of the absence of this bone, since it is loosely attached and easily lost in preparation, leaving little or no evidence on the quadrate of its former presence. When present, the squamosal is separated from the jugal by the postorbital. The orbito-nasal foramen, which houses the palatine artery and an anastomotic artery that joins the artery of the Vidian canal, is on the floor of the cavernosum canal lateral to the border of the basisphenoid and anterior to the primitive caroticum foramen. The ethmoid fissure is broad and the postlagenar hiatus large and rounded. The anterior part of the inferior parietal process flares strongly outward, touching the jugal. Triturating surfaces of the jaws are narrow and ridgeless. The upper jaw has a medial notch bordered by two toothlike cusps. The snout is slightly projecting and the posterior surface of the head is covered with small scales. Head and neck are brown; the chin and throat become pale in old individuals. Young individuals may bear a yellow longitudinal stripe over each eye and another from the corner of the mouth backward to the neck. Limbs are brown and have transversely enlarged scales. The toes are webbed, and the tail is not exceptionally long.
Carr and Bickham (1986) reported a karyotype of 2n = 52; 28 macrochromosomes (18 metacentric or submetacentric, 10 telocentric or subtelocentric) and 24 microchromosomes.
Males have slightly concave plastra and thicker tails than do the flat-plastroned females. During the breeding season, the nose of the male may show a red coloration (Philippen, 1988).
Distribution
Notochelys platynota ranges from peninsular Thailand southward through Malaysia, Sumatra, and Java to Borneo. There is also a dubious record from southern Vietnam; those from Myanmar may be in error (Van Dijk, 1993).
Habitat
Shallow waters with soft bottoms, abundant vegetation, and slow currents, such as swamps, marshes, streams, and ponds in jungle areas, are preferred. Nutphand (1979) reports this turtle from clear mountain streams.
Natural History
Nothing is known of the reproductive behavior of this species. Three eggs found inside a dead female measured 56 x 27-28 mm (Philippen, 1988). The hatchlings are more brightly colored than adults and more strongly serrated, have a more pronounced keel, and are about 55-57 mm in carapace length.
Notochelys platynota is a herbivore, feeding predominantly on aquatic plants. In captivity it accepts a variety of vegetables, but prefers fruits, such as bananas, and also exhibits carnivory (Buskirk, 1997).
Flower (in Smith, 1931) remarked that when a wild Notochelys is disturbed it pulls into its shell with a hiss, and if picked up, defecates on the handler. Unfortunately, captives retain the defecation habit.
IUCN Red List Status (1996)
Data deficient.