Common toad-headed turtle
The oval to elliptical (usually broadest behind the center), flattened, brown to olive-gray carapace (to 31.7 cm) has a smooth posterior rim. There is usually no medial groove, but a low vertebral keel may be present on younger individuals. The flared 1st vertebral is the largest and broader than long; the 5th, which is also flared and broader than long, is second largest; vertebrals 2-4 are broader than long in juveniles, but become longer with growth until they may be slightly longer than broad; the 4th is smallest. The cervical scute varies from small to long and narrow. The plastron is well-developed and has an anal notch. Its forelobe is rounded anteriorly and is broader than the hindlobe, which does not strongly taper toward the rear. The bridge is relatively broad. The plastral formula is usually: intergul > fem >< abd >< an >< pect >< hum > gul; the intergular completely separates the gulars. Plastral coloration is variable, consisting of a yellow ground color with or without brown pigmented areas. The head is large and very broad with a slightly projecting snout and an upper jaw with only a slight notch. Two chin barbels are present. The upper surface of the head is covered with small to large, irregularly-shaped scales. The head is distinctly bicolored (brown or gray dorsally, yellow ventrally) with some orangish smudges. The neck is darker dorsally and lighter ventrally, and may bear some blunt tubercles. Limbs are gray on the front and sides but cream beneath.
Killebrew (1976) reported the karyotype as 2n = 50 (26 macrochromosomes, 24 microchromosomes), but both Gorman (1973) and Bull and Legler (1980) found the diploid number to be 58 (22 macrochromosomes, 36 microchromosomes).
Males have longer, thicker tails and may have concave plastra.
Phrynops nasutus lives in French Guiana, Surinam, and possibly northeastern Brazil.
Currently, no subspecies are recognized.
This turtle has been taken from a variety of slow-moving aquatic habitats, such as forest marshes, inundated woodlands, and muddy ditches (Pritchard and Trebbau, 1984).
Little life history data is available. Hatchlings have 59-60 mm carapaces, and P. nasutus is probably carnivorous, as are other Phrynops, but no wild foods have been reported.
IUCN Red List Status (1996)