Annelida Polychaeta.

The following list gives the polychaete species recorded in the Italian seas. A total of 876 species belonging to 71 families of the Polychaeta Class are listed. Fifty species new to the Italian fauna, representing more than the 5% of the total number of species, have been added to the pre-vious edition of the "Checklist della fauna italiana" (Castelli et al., 1995). Various papers reporting the results of a wide-ranging census programme of the Italian polychaete fauna and already cited in the previous edition of the check list represent the bibliographical background to the present list (Gambi et al., 1985; Castelli et al., 1987; Castelli et al., 1995). This chapter is based on that baseline list and numerous other publications. Moreover, personal observations by the authors of this chapter and other researchers working on polychaetes along the Italian coastline have supplemented the present checklist. Notes, bibliographical references describing significant changes from the previous list (Castelli et al., 1995), including particularly important modifications of species geographical distribution and the most important synonymies have been added to the text. The reassignments of records from a larger to a more limited geographical area following the new concept of the subdivision of the Italian seas (Bianchi, 2004) have not been referenced. In general, the placement of the polychaete Families within the Orders follows the Linnean ranking used by Vieitez et al. (2004) for the polychaetes of the Iberian fauna. However, it must be stressed that, based on the cladistic analysis of Rouse & Fauchald (1997), Rouse & Pleijel (2001) consider two main groups within Polychaeta: Scolecida and Palpata. This latter group has been further divided into Aciculata and Canalipalpata, which were not assigned to any Linnean rank. These two clades are subdivided into taxonomic ranks roughly corresponding to the "classic" Linnean Orders. In Tab. 1 the taxonomic scheme proposed by Rouse & Pleijel (2001) and the one proposed by Vieitez et al. (2004) are compared. The two schemes partially overlap with some noticeable exceptions. The nomenclature of every Family is based on taxonomic revisions of the Family itself or its sub-ranks. Within each Family (or Sub- Family when present) the Genera are listed in strict alphabetical order. Within each Genus (or Sub-Genus when present) the species are listed in strict alphabetical order. The most important changes from the previous edition (Castelli et al., 1995) concern some Families that have been the object of particular study during the last ten years in the Mediterranean Sea and along the Italian coastline. In general, careful bibliographic analysis and the research effort spent in the recent period on the analysis of the Italian polychaete fauna permit us to consider the present list a satisfactory picture of the species distribution. However, the numerous changes from the previous edition and the results of some future large-scale sampling campaigns in the Italian seas indicate that the present list may have to be further modified over the next few years.