The genus Alterosa Blahnik, 2005 (Trichoptera, Philopotamidae, Philopotaminae) in northeastern Brazil, including the description of three new species and an identification key for the genus.

Alterosa Blahnik, 2005 contains 35 described species distributed in southern and southeastern Brazil. Three new species of Alterosa from northeastern Brazil are described and illustrated, Alterosa amadoi sp. n., Alterosa castroalvesi sp. n. and Alterosa caymmii sp. n., the first records of the genus from northeastern Brazil. An identification key for all known species of the genus is also presented.