Abstract
A new species of Nephtyidae, Inermonephtys brasiliensis, is described from material previously referred to I. palpata Paxton 1974 from off São Paulo and Paraná States, SE Brazilian coast. The new species is characterized by interramal branchiae starting from setiger 3, basal papillae starting on setiger 5, and two kinds of lyrate setae. Several lyrate setae occur as a postacicular spiral bundle in both noto- and neuropodia all along the body, showing two different morphologies (i.e., very short or very long tines). Lyrate setae with long tines are the most common, while those with short tines are more difficult to distinguish and may be absent in some parapodia. A redescription of I. palpata is also provided.