A new species of Procamallanus Baylis, 1923 was found as a parasite of the fish Astronotus ocellatus (Agassiz, 1831) from a lake in the Jardim Botânico Bosque Rodrigues Alves, Belém, Brazil. Procamallanus spiculastriatus sp. n. has a smooth buccal capsule and a well-developed basal ring that is armed with four sclerotized tooth-like structures. The male of the new species is similar to the two species that are known from Brazilian fish, P. peraccuratus Pinto, Fábio, Noronha & Rolas, 1976, and P. annipetterae Kohn & Fernandes, 1988, by the absence of the gubernaculum. It differs from these two by the morphology of the buccal capsule, the number are arrangement of the caudal papillae in males, the size and morphology of the spicules and the shape of the tail of both sexes. Procamallanus spiculastriatus sp. n. is the third species discovered in fish from Brazil. This finding extends the geographical distribution of the genus into the Brazilian Amazon.