A new species of Nereididae (Annelida Polychaeta) from the Island of Ustica (northern Sicily, Italy).

A new species of Nereididae, Nereis usticensis n. sp., found among Cystoseira species, on the hard bottoms o infralittoral upper zone of the Island of Ustica, is described. Particular features of the new taxon are the posterior notopodial homogomph falcigers, with one terminal tooth and two or three smaller, lateral ones an( the distribution pattern of paragnaths On maxillary and oral rings. A comparison with similar species is offered.