Pionosyllis Malmgren, 1867 is revised based on a cladistic analysis of the 41 species considered herein as valid, two newly described species in this paper (Basidiosyllis victoriae and Opisthodonta russelli), 11 species from other genera actually belonging,

The external gestation of sexually ripe females of the species Exogone naidina (Polychaeta, Syllidae) is described by means of SEM and TEM analysis. The eggs, embryos and juveniles are attached in close vicinity of each parapodial complex in a position

The present study describes polychaete assemblages on three shallow-water benthic habitats, Ulva rigida, Cytoseira barbata and Mytilus galloprovincialis, in relation to space and time from the Sinop Peninsula (Turkish Black Sea coast). A total of 55 polychaete