The polyplacophoran (Eumollusca, Mollusca) fauna of the Aegean Sea with the description of a new species, and comparison with those of the neighbouring seas ATHANASIOS KOUKOURAS* and PARASKEVI KARACHLE  Department of Zoology, School of Biology, Aristotle University of Thessaloniki, GR - 54124 Thessaloniki, Greece Abstract Sampling carried out in the Aegean Sea revealed the presence of 14 chiton species. One new species, Ischnochiton (Haploplax) tsekosi, is described and another species, Lepidopleurus (Leptochiton) algesirensis, is recorded for the first time from the Eastern Mediterranean. For all species, information on their distribution and habitat is given. A checklist of the Mediterranean and Black Sea chitons, as well as their distribution in the Mediterranean territorial areas and the Black Sea, is also presented. Furthermore, the faunas of the Mediterranean territorial areas are compared. According to the considered data, the number of species decreases as follows: Western Mediterranean, Central Mediterranean, Aegean Sea, Adriatic Sea, Levantine Sea and Black Sea. Species with an Atlanto-Mediterranean distribution dominate in all areas and are followed in numbers by the Mediterranean endemics and cosmopolitans.   < back .