A new species of Orientatractis (Nematoda: Cosmocercoidea: Atractidae) parasite of Yellow-Spotted Amazon River Turtle, Podocnemis unifilis Troschel, 1848 (Testudines: Podocnemididae) in Brazilian Amazon.

The current study describes a new species of nematode, Orientatractis matosi n. sp. (Atractidae), from the stomach and large intestine of Podocnemis unifilis Troschel, 1848 (Testudinidae), collected in the Tocantins and Xingu rivers in the Brazilian state of Pará. The new species was described using light and scanning electron microscopy and differs from its congeners mainly in the number and distribution of the male caudal papillae and by having a shorter right spicule. Orientatracits matosi n. sp. is the eleventh species of the genus Orientatractis Petter, 1966, the third reported from the Amazon, and the second described from P. unifilis. [Display omitted] • Orientatractis matosi n. sp. (Atractidae) is a new parasite of Podocnemis unifilis (Testudines: Podocnemididae) from the Amazon region. • This is the second known species of the genus Orientatractis in P. unifilis. • Orientatractis matosi n. sp. has nine pairs of caudal papillae and the shortest right spicule amongst its congeners. • Orientatractis matosi n. sp. is the third species reported from the Amazon region. [ABSTRACT FROM AUTHOR]