Acanthoatractis xinguensis n. gen., n. sp. (Nematoda: Cosmocercoidea: Atractidae) parasite of yellow-spotted Amazon river turtle, Podocnemis unifilis Troschel (Testudines: Podocnemididae) in Brazilian Amazon

Nematodes collected from the stomach of the yellow-spotted turtle Podocnemis unifilis Troschel, 1848 (Testudinidae) in the Brazilian state of Pará are assigned to a new genus, allocated to the family Atractidae (Cosmocerdoidea). Acanthoatractis n. gen. differs from all other genera of Atractidae based on the combination of the following morphological characters: cephalic extremity surrounded by eight bifurcated, wrench-shaped sclerotized structures arranged in a circle; oral opening encircled by two sclerotized pieces with pointed ends and a median portion with a pair of hooks; in males the larger (left) spicule is narrower in the middle third and the gubernaculum is absent. The type species, Acanthoatractis xinguensis n. gen., n. sp., has nine pairs of caudal papillae and a single papilla anterior to the cloacal lip. The new species is the seventh record of an atractid genus parasitizing P. unifilis. [Display omitted] •A new genus and species of atractids parasitizing freshwater turtles from the Amazon region.•Acanthoatractis n. gen. differs from all other genera by the shape of sclerotized structures on the cephalic end.•This is the 27th genus of the family Atractidae.•This is the seventh record of an atractid genus parasitizing Podocnemis unifilis.