Polydora websteri—A Commensal of Anadara kagoshimensis in the Azov-Black Sea Region

The occurrence of polychaete borers was recorded from the alien clam Anadara kagoshimensis (Tokunaga, 1906) at Chushka Spit near Port Kavkaz in January 2020. On the basis of morphological analysis, the polychaetes were identified as Polydora websteri Hartman in Loosanoff & Engle, 1943, alien to the Azov-Black Sea basin. This species was recorded for the first time from coastal waters of Romania on carbonate rocks in 1997 and, subsequently, coastal areas of Sevastopol and Lake Donuzlav in oysters Crassostrea gigas (Thunberg, 1793) in 2009 and 2019. Polydora websteri was not previously recorded from the Kerch Strait and the Sea of Azov. This is the first report of its occurrence in Anadara kagoshimensis in the Azov-Black Sea region, which is an invasion area for both species.