To Be or Not to Be Alien, That is the Question: the Case of Five New Polychaete Species from the Levantine Sea

A series of sampling activities in the Tyre Coast Nature Reserve, on the Southern coast of Lebanon, in the context of the project Blue Tyre - Local Partnership for Sustainable Marine and Coastal Development, allowed for the collection of material to study the polychaete fauna of the area, with particular focus on Non-Indigenous Species (NIS). The detection of several taxonomical novelties resulted in the description of five new species belonging to four families: Dorvilleidae, Eunicidae, Nereididae, and Sabellidae. Based on clear differences compared to the historical polychaete fauna of the Mediterranean Sea and on the presence of morphological similarities or genetic correspondence with Indo-Pacific taxa, we suggest that, despite having Mediterranean type locality, the newly described species should be considered NIS in the Mediterranean. Thus, the present data reaffirm the importance of the Levantine Sea and the Lebanese coast as an outpost for the early tracking of bioinvasions in the Mediterranean area. Specific epithets of Pseudobranchiomma Jones, 1962 species are amended to their correct Latin gender, following article 30.1.2 of the I.Z.C.N. Lastly, a review of the available literature on both the genera Nereis Linnaeus, 1758 and Lysidice Lamarck, 1818 reveals the necessity of corrections to the taxonomic status of some species within these genera.