Thursday, March 31, 2016

Yellow-headed Sideneck Turtle, Podocnemis unifilis (Family Pelomedusidae)

Occurs as a waif in Trinidad waters. A 10 September 2012 a story in Newsday reported several individuals of this species on Manzanilla Beach; the article included a photograph confirming the identity of the turtles as this species.
Maximum carapace size about 680 mm in females, about 330 mm in males; hatchlings are about 40 mm in carapace length. 
Carapace dark brown to black, oval with a low medial keel on the second and third vertebral scutes; posterior portion is flared; overall coloration is mostly gray; it lacks the interorbital groove found in all other species of the genus Venezuelan specimens tend to have a single chin barbel. Juveniles have yellow and orange head spots including one on the snout; these fade quickly in females but are retained by adult males. Similar species: Perhaps most easily confused with Podocnemis expansa that has only yellow head spots, and lacks the spot on the snout; it also lacks the medial keel found in this species. Smooth skin on the head of this species will distinguish it from Mesoclemmys gibba which has granular skin on its crown. 

Widespread in the Amazon and Orinoco basins. 

A highly aquatic species, that basks on occasion, it uses small streams, ponds, and flooded forest and during the dry season restricts it activity to remaining bodies of water. Diurnal, but nesting occurs at night. 

Its diet is mostly herbivorous including fruits, stems, and leaves of aquatic plants; but also includes molluscs and dead fish. 

It nests earlier in the season than P. expansa, and females do not form the large nesting aggregations that its congener does. Nesting occurs on sandbanks close to the water. Clutch sizes range from 19−41 with larger females producing more eggs. This turtle is hunted by humans for food.

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