The present paper deals with the isopods present in the stomach content of Sympterygia acuta and S. bonapartei, two species of Rajidae frequently found along Rio Grande do Sul coast. Eight species of isopods were found in the stomachs analysed, and Ancinus gaucho sp.n. showed to be an important food resource for the fishes, especially for S. bonapartei. The difference found in the diet composition of both species of skates seems to reflect a non selective feeding of the fishes on distinct benthic communities. The description of Ancinus gaucho is also furnished herein as well as a key to the known species of the genus.
Stomach content; New species; Taxonomy; Identification keys; Ancínus gaucho; Isopoda; Rajidae; Rio Grande do Sul; Brazil