(Cuvier, 1825)
Indian softshell turtle
Recognition
The round to oval carapace (to 94 cm) is olive or green, with or without black reticulations; yellow-bordered, dark-centered ocelli are not present, or are poorly developed, in adults, but are often well-developed in juveniles. Several longitudinal rows of tubercles occur on the juvenile carapace, but that of large adults is smooth. A preneural and a neural separate the 1st pair of costals. The 8th pair of costals is large and meets at the midline. Carapacial bones have pitted surfaces. The plastron is gray to white or cream. The callosities are large in the region of the hyo-hypoplastra, xiphiplastra, and entoplastron. The epiplastra nearly touch in front of the entoplastron, which lies at obtuse or right angles to the midline. The skull is broad and the blunt bony snout is short and broad (shorter than the diameter of the eye) and slightly downturned. The wide triturating surface of the maxilla is ridgeless but somewhat rugose. That of the mandible is wide with a sharp ridge along the inner edge which sends off a short perpendicular process at the symphysis. Mandibular diameter at the symphysis is shorter than the diameter of the orbit. The head is green above with several black oblique stripes running toward the sides, one of which runs backward from the lower edge of the orbit. A black medial longitudinal stripe may extend backward from between the orbits to the nape. The jaws are yellowish and the chin and throat cream to whitish. The limbs are green and usually unmarked.
Males have longer, thicker tails than females, with the vent beyond the carapacial rim near the tip of the tail.
Distribution
Aspideretes gangeticus lives in the Ganges, Indus, and Mahanadi river systems in Pakistan, northern India, Bangladesh, and southern Nepal.
Geographic Variation
No subspecies are currently recognized, but variation does exist.
Habitat
This large softshell inhabits deep rivers, streams, and large canals, lakes and ponds with mud and sand bottoms. It seems to prefer turbid waters (Minton, 1966).
Natural History
Mating occurs in shallow water during the monsoon season. Günther (1864) reported the Indian softshell produces low, hoarse, cackling sounds, possibly related to courtship, but Vyas and Patel (1992) did not hear such sounds while observing courtship and mating in this turtle. They reported that the male blocked the path of a receptive female, slowly swam in decreasing circles around her as he moved closer, mounted her carapace from behind while grasping the female's forelimbs with his claws, and grasped the ventral side of her carapace with his hindlimbs prior to intromission. Total time elapsed in courtship was 4-5 minutes. While mounted, the two turtles float, protruding their heads to breathe, and the male squirts water out his nostrils. Copulation took 30-50 minutes.
Nesting occurs between May and January, with a peak in December and January (Das, 1995); however, Vasudevan (1996) reported that nesting in 1992 began on 31 July and ended on 30 October along the Chambal river in central India. The nest is dug in sandy river banks with both hindlimbs excavating alternately (Tikader and Sharma, 1985; Vyas and Patel, 1992). Flask-shaped nest cavities are 17-31 cm deep, with a neck 6-16.5 cm wide and 7-16 cm long, and an broadened egg chamber 11-20.5 cm wide and 8-20.5 cm high (Vasudevan, 1996).
Clutches contain 8-47 (usually 15-20) white, hard-shelled, spherical (23-34 mm) eggs (Das, 1991, 1995; Vyas and Patel, 1992; Vasudevan, 1996). Incubation may take 251-310 days, and hatching takes place simultaneously when there are rains after summer in July (Vasudevan, 1996). Vasudevan (1996) reported hatching percentages of 0-100%, but of those clutches that produced young the percentage of hatching was 88.2-100%.
Hatchlings have 43.0-47.0 carapaces and weigh 9-12 g (Vyas and Patel, 1992; Das, 1995). The number of ocelli on their bright olive carapace varies from three to six (mean 4.3), and 3-5 black lines and a black stripe run backward from behind the eyes and poster forehead.
This species is omnivorous, eating not only mollusks, insects, fish, amphibians, waterfowl, and carrion, but aquatic plants as well. Minton (1966) reported they emerge to bask on sandbanks, and may thermoregulate by resting in shallow waters.
IUCN Red List Status (1996)
Not listed.