Four new nereidid polychaete species are described; all were sampled during the MUSORSTOM oceanographic cruises. Leonnates crosnieri n. sp. (New Caledonia) resembles L. indicus Kinberg, 1866 but the former has pharynx area VI with 18-19 papillae in group, and superior lobe is present throughout the body. Neanthes philippinensis n. sp. (Philippine Islands) is closely allied to N. maculata Wu, Sun & Yang, 1985 but it differs by having only one line of five paragnaths on pharyngeal area VII-VIII. Neanthes pleijeli n. sp. (Philippine Islands and New Caledonia) resembles N. anchylochaeta Horst, 1924 but it differs by lacking cones in pharynx areas II, III, IV, V and VI. Nicon pettiboneae n. sp. is a deep water species (Philippine Islands and New Caledonia); it differs from other species by the presence of neuropodial infracicular sesquigomph falcigers in all parapodia.
Annelida, Polychaeta, Nereididae, Indo-Pacific, new species.