Six-tubercled river turtle  (Podocnemis sextuberculata)

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

The six-tubercled river turtle is named for the six pairs of prominent, swollen lumps that are found on the outer edge of the underside of the juvenile’s shell (the plastron), where it meets the upper surface (the carapace). The swellings typically disappear as the turtle ages, but may remain present in some adults. Other characteristic features of this species are a domed and elliptical shell, with broad, smooth scutes, and a serrated rim at the rear exhibited in the juveniles, but which disappears in adulthood (2). The upper shell is grey to olive-brown, while the lower part is yellowish-grey or brown. The head is coloured olive to reddish-brown becoming cream on the jaws, and is broad, with a protruding snout, a deep groove between the eyes and one or two chin barbells. The neck and limbs are dark grey to olive, and the male possesses a longer, thicker tail than the female (2).

The six-tubercled river turtle is found in the Amazon drainage of northern Brazil, north-eastern Peru and south-eastern Colombia (1) (2)

A freshwater species, the six-tubercled river turtle inhabits rivers and other water bodies within the Amazon drainage (2).

The six-tubercled river turtle feeds on aquatic plants and fish (2), using its wide gape and powerful jaws to capture prey (4). The nesting season of this species varies according to location, but usually falls between June and October (2). After mating, the females make lengthy migrations, averaging 18 kilometres in northern Brazil, to the nesting sites (5). Eggs are laid after dark in holes excavated on the sandy banks of rivers, which are exposed when the rivers are low (5) (6). Clutches number between 7 and 22 soft-shelled, creamy-white eggs, which are covered over with sand and left to incubate, while the female returns to the river (2) (6). On hatching, the young turtles’ carapaces measure between 45 and 47 millimetres long (2).

Like many turtle species, the six-tubercled river turtle is hunted for human consumption. In some areas, the exploitation is heavy, with hundreds of individuals collected each week in Tefé, north-west Brazil (7). Overexploitation has already drastically reduced the populations of two related turtle species from the same region, the Giant South American turtle (Podocnemis expansa) and the yellow-headed sideneck turtle (Podocnemis unifilis), and without intervention, it is likely that the six-tubercled river turtle will suffer the same fate (7).

In order to preserve heavily exploited turtle species, such as the six-tubercled river turtle, it is imperative that sustainable use programmes are implemented and effectively managed (7). In addition, protection is required for the waterways used by this species to travel from feeding grounds to the nesting sites (5).

View information on this species at the UNEP World Conservation Monitoring Centre.

To learn more about turtle conservation visit:

• Chelonian Research Foundation:
  www.chelonian.org
• Behler Chelonian Center:
  http://chelonianconservation.org
• Turtle Conservation Fund:
  www.turtleconservationfund.org