Nilssonia gangetica (Cuvier, 1825)

Identification Basis

This species is identified based on the structure of its carapace and plastron.

Costal Plate Structure

It has eight pairs of costal plates, with the last pair fully developed and in complete contact along the median line.

Neural and Plate Surface Features

There are two neurals between the first pair of costals, and the plates are coarsely pitted and vermiculate.

Epiplastron and Entoplastron Structure

The epiplastra are narrowly separated from each other in front of the entoplastron, which forms an obtuse or right angle.

Plastral Callosities

Plastral callosities are very large, present on the hyo-hypoplastral and xiphiplastral plates, and also present on the entoplastral plate in older specimens.

Juvenile Dorsal Skin

The dorsal skin of young individuals has longitudinal ridges of small tubercles.

Head and Snout Size

The head is moderately sized; the snout (on the skull) is roughly as long as the diameter of the orbit.

Interorbital Region

In adults, the interorbital region is considerably narrower than the nasal fossa.

Postorbital Arch Measurement

The postorbital arch measures between one third and one half of the greatest diameter of the orbit.

Mandible Inner Edge Structure

The inner edge of the mandible is strongly raised to form a sharp ridge, which extends a short perpendicular process at the symphysis.

Mandible Symphysis Diameter

The diameter of the mandible at the symphysis does not exceed the diameter of the orbit.

Dorsal Coloration

The upper side of the turtle is olive-colored.

Juvenile Back Markings

The back of young individuals is vermiculated with fine black lines, and does not have ocelli.

Head Markings

The head has a black longitudinal streak running from between the eyes to the nape, which is intersected by two or three inverted-V shaped black streaks.

Ventral Coloration

The lower parts of the body are yellowish.

Dorsal Disk Size

The length of the dorsal disk reaches 2 feet.

Distribution Range

This species occurs in the Indus, Ganges/Padma, Meghna, Brahmaputra, Jamuna, Narmada and Mahanadi basins, most of their tributaries, and intervening drainages, within the countries of Afghanistan, Bangladesh, India (including the states of Assam, Bihar, Gujarat, Jammu & Kashmir, Madhya Pradesh, Orissa, Punjab, Rajasthan, Uttar Pradesh and West Bengal), southern Nepal, and Pakistan.