A new species of and an annotated checklist of polychaetes from mangroves of the Brazilian Amazon Coast (Annelida, Paraonidae).

The polychaete fauna from the mangroves of the Amazon Coast in Maranhão state, Brazil, is reported in this study. Fourteen species are listed, namely (Leuckart, 1847); Arabella (Arabella) iricolor Montagu, 1804; (Fabricius, 1780) complex; Exogone (Exogone) breviantennata Hartmann-Schröder, 1959; (Claparède, 1864); Müller, 1858; Hartman, 1944; Nageswara Rao, 1981; (Gravier, 1901); (Saint-Joseph, 1901); Perkins, 1980; ; (Hartman, 1945); and Müller, 1858. Among them, and are recorded for the first time in Brazil. is a new species for science, characterized by a rounded prostomium, 4-8 pairs of foliaceous branchiae, absent eyes, and two types of modified neurochaetae, acicular and hook-shaped.