A new species of Clavellotis Castro et Baeza, 1984 (Copepoda, Lernaeopodidae) parasitic on Patagonian redfish, Sebastes oculatus Valenciennes, 1833 from southern coast of Argentina is described and illustrated. The new species of Clavellotis differs from its congeners by the length of second maxilla, shape of the female trunk, length of genital process, and a combination of characters. The male also shows differences in the second maxilla, the maxilliped and in the shapes of the trunk and genital process. This is the first record of Clavellotis from the southern Atlantic Ocean and also the first record on a Sebastes species.