Grisin des marais Formicivora acutirostris

Small long-tailed antwren with a very restricted range; occurs in marshes with tall grasses and scattered bushes in the state of Parana and is usually very hard to see. Two similar-looking forms occur, which may be distinct species. Both sexes are mostly brown above with bold spots on darker wings. Males of the São Paulo form are black below whereas southern birds are gray below.