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.