The oval carapace (to 31 cm) is flattened dorsally, has an indentation at the broad cervical, and is strongly serrated around its entire rim. Posterior marginals are somewhat upturned, and pleurals somewhat concave. Vertebrals are wider than long, and the 5th is expanded. Günther (1882) reported a slight indication of a medial keel on the 4th and/or 5th vertebrals. Well-defined growth annuli surround the flat vertebral and marginal areolae. Eleven marginals lie on each side, and two supracaudals. The carapace is yellowish brown to brown with dark seams, but some have dark radiations along the outer border of each scute. Large black blotches occur on the marginals. The plastron is well-developed with a deep anal notch and a broad anterior notch which somewhat separates the gulars. Its forelobe is longer but narrower than the hindlobe. The plastral formula is: abd > hum > fem > gul >< an > pect; the gulars are thickened and extend slightly beyond the carapacial rim. The bridge is wide; the inguinal is large and often subdivided, and the axillary is small to moderate. The plastron is yellowish brown with darkened seams, and some dark streaking may be present. The head is large with a nonprojecting snout and an upper jaw which lacks a hook, or is only slightly hooked. Its large prefrontal is longitudinally divided, and followed by a large undivided frontal scale; other head scales are small. The maxillae are ridged, but the premaxillae are not. The head is yellow to tan with pink pigment about the snout on some. Forelimbs are black; hindlimbs and tail dark brown. The anterior surface of the somewhat flattened forelimbs is covered with large, overlapping pointed scales. A single large conical tubercle lies on each thigh, and the tail may end in a horny scale.
Males have longer, thicker tails than do females. In males the ventral scales of the tail are placed pairwise and make regular contacts at the midline, but in females these scales are staggered and form a zigzag line of medial contact (Chan-ard et al., 1996).
Manouria impressa ranges from the Karenni Hills in Myanmar to Malaysia and to Vietnam. It has also been found in Hunan Province, China (Zhao, 1986), but this individual probably was introduced (Buskirk, 1989a).
This tortoise inhabits evergreen forests and bamboo thickets on hills and mountains. McMorris and Burns (1975) thought the natural habitat seems to be fairly dry, and not usually associated with water bodies. The tortoises rely on heavy dew or rain-drenched vegetation for water. In the wild they spend much time hiding under leaf litter.
Nutphand (1979) reported the mating season coincided with the rainy period; Chan-ard et. (1996) observed courtship activity from mid-March to September. A courting male approaches a female from the front and bobs his head up and down while simultaneously opening and closing the mouth. If receptive, the female raises her body high, and the male moves to her rear and mounts. The male stretches his neck and vocalizes during copulation, but does not bite or ram the female.
The eggs are laid in a shallow cavity and then covered with leaves; McMorris and Burns (1975) reported that a female laid 17 eggs between 16 and 29 May. Hatchlings are yellowish to light brown with rounded, medially keeled, heavily serrated carapaces. Chan-ard et al. (1996) calculated that the hatchling carapace is approximately 50 mm long.
Manouria impressa seems to be more active at twilight and during showers. The natural diet is composed almost entirely of the mushrooms Pleurotus, Amanita, Auricularia, and Termitomyces, and to a lesser degree Tricholoma, Russula, and Favolus (Chan-ard et al., 1996). Data on captive diet can be found in Nutphand (1979), McMorris and Burns (1975), Weissinger (1987), and Espenshade and Buskirk (1994).
IUCN Red List Status (1996)
Vulnerable (A1acd, B1+2acd). This rare species is declining in the wild. The major threats to its survival are exploitation for Chinese and Vietnamese food markets and habitat loss from agricultural expansion and uncontrolled forest fires (Chan-ard et al., 1996).