Hysterothylacium rhamdiae sp.n., (Ascaridoidea: Anisakidae) from a Neotropical Catfish, Rhmdia sapo (Pisces: Pimelodidae)

A new species of Hysterothylacium is described and figured. The nematodes were collected from the intestine of a neotropical catfish, Rhamdia sapo, collected from its southernmost locality (Napostá stream and Sauce Grande river, Buenos Aires Province). The specimens resemble H. murrayense but differ in having a shorter spicules, in the number and distribution of papillae and the relative size of intestinal caecum ventricular appendix.