Heosemys grandis

(Gray, 1860a)
Giant Asian pond turtle

This is one of the largest hard-shelled, semi-aquatic Asian turtles, reaching a carapace length of 43.5 cm. The broad, oval carapace is high arched but depressed dorsally and serrated posteriorly. A well-defined, blunt medial keel is present, and all vertebrals are broader than long. In color, the carapace is brown to grayish brown or black, and a pale streak may occur along the keel; in some, light seams appear between the scutes. In younger individuals, the growth annuli are prominent. The plastron is large and notched posteriorly. Both the anterior and posterior lobes are narrower than the medial portion. The plastral formula is: abd > fem > pect > an >< hum >< gul. The bridge is well-developed and longer than the plastral hindlobe. Both axillary and inguinal scutes are present. Plastron, bridge, and undersides of the marginals are yellow. In juveniles a pattern of dark lines radiating outward from a large dark central blotch occurs on each scute, but these disappear with age and the scutes are uniformly yellow in older turtles. Head and neck are broad, snout only slightly projecting, and the upper jaw contains a shallow medial notch flanked by a pair of toothlike cusps. Skin covering the posterior portion of the head is divided into irregularly shaped scales. The head is grayish green to brown with numerous yellow, orange, or pink mottled spots, which disappear with age so that old turtles may have only a few remaining. Jaws are cream to horn colored; forelimbs large with broad scales on the anterior surface. All toes are webbed.
The karyotype is 2n = 52; 28 macrochromosomes (18 metacentric or submetacentric, 10 telocentric or subtelocentric) and 24 microchromosomes (Carr and Bickham, 1986).
Males have slightly concave plastra and longer, thicker tails than the flat-plastroned females.

Heosemys grandis ranges from Pegu, Myanmar to Vietnam and south through the Malay Peninsula.

This turtle inhabits various fresh waters, such as rivers, streams, swamps, lakes, and marshes from hill country to sea level. It is not restricted to water, and spends much time on land partially hidden under shrubbery. Captives may spend most of the time out of water.

Natural History
Despite its size, its habits are poorly known. In zoos, males have been seen biting at the neck and head of females, and possibly this is part of the courtship ritual. Pritchard (1979) reported that juveniles have a large fontanelle or "soft spot" in the middle of the plastron.
Taylor (1970) and Nutphand (1979) reported they feed mainly on aquatic plants in the wild, but captives are generally omnivorous.
This turtle, along with Hieremys annandalii, is often placed in the Tortoise Temple in Bangkok.

IUCN Red List Status (1996)
Lower risk: near threatened.