A new species of Pseudanisakis Layman & Borovkova, 1926 (Nematoda: Ascaridida) from Rioraja agassizii and Psammobatis extenta (Rajidae) in Brazilian southwestern Atlantic waters.

Pseudanisakis sulamericana n. sp. is described from the intestines of the rays Rioraja agassizii and Psammobatis extenta off the coast of Brazil. It can be readily differentiated from the three existing species of the genus. From P. tricupola Gibson, 1973, it differs in not having cupolas on the lips, having a dentigerous ridge of 90-95 denticles ( vs 65-78) in a continuous subtriangular ring around the mouth, and in having an ejaculatory duct which is shorter than the spicules. From P. rajae (Yamaguti, 1941), it differs in having a single rather than a double row of denticles. It appears most similar to P. baylisi Gibson, 1973, but differs from it in having a smaller body-size (7.5-27 vs 16-46 mm), shorter spicules (1.14-1.90 vs 1.90-3.80 mm) and especially in having much more conspicuous denticles on the lips. The present record confirms the presence of the genus in subtropical waters.