The diversity of polychaetes (Annelida: Polychaeta) in a long-term pollution monitoring study from the Levantine coast of Turkey (Eastern Mediterranean), with the descriptions of four species new to science and two species new to the Mediterranean fauna

During a relatively long-term pollution monitoring study between 2015 and 2021 (annually between 2015 and 2019; triennially after 2019), a total of 257 polychaete species belonging to 40 families were identified at 17 soft bottom stations (depth range: 11-89 m) along the Levantine coast of Turkey. Among them, four species belonging to Hesionidae (Oxydromus digitifera sp. nov.), Orbiniidae (Leitoscoloplos mediterranea sp. nov.), Paraonidae (Paraonis lobulata sp. nov.) and Capitellidae (Barantolla cryptogenica sp. nov.) are new to science, two species belonging to Cirratulidae (Chaetozone elakata) and Ampharetidae (Anobothrus amoureuxi) are new additions to the Mediterranean fauna and 28 species are new additions to the marine fauna of Turkey. Among the families, Spionidae (29 species), Syllidae (22 species) and Paraonidae (22 species) accounted for 28% of the total number of species, and Capitellidae, Lumbrineridae and Spionidae comprised 45% of the total number of individuals. The most dominant species in the region were Lumbrineris geldiayi, Notomastus mossambicus and Prionospio saccifera. A total of 20 alien species belonging to 12 families were found in the region, with N. mossambicus and P. saccifera accounting for more than 85% of the total number of individuals of alien species. The new species are described and compared to the closely related species.