Two atractid nematodes are reported from the large intestine of freshwater turtles of the genus Podocnemis in Colombia. Paratractis hystrix (Diesing, 1851) is redescribed in detail using the scanning electron microscope and is reported from P. expansa, P. vogli and P. unifillis, the last being a new host. Buckleyatractis marinkelli n. g., n. sp. from P. unifillis is characterized by the nature and arrangement of the spines on the body, particularly the dorsal crest restricted to the cervical region and formed of three longitudinal rows of large spines.