Aracia sp. (Polychaeta: Sabellidae) from the Don River estuary (Sea of Azov basin).

During the monitoring investigations in the Don River estuary, an alien polychaete species of the family Sabellidae was recorded. Polychaete specimens were collected two times within a month, in the later sample one specimen had eggs in anterior abdominal chaetigers. The description of present specimens is provided. All the specimens match the diagnosis of the genus Aracia Nogueira, Fitzhugh et Rossi, 2010. However, there is an uncertainty at the species level: both A. riwo and A. heterobranchiata characters are present, though the latter seems to be more likely. Probable way of penetration into the Don River estuary is ballast water tanks, for many tankers use to spill their ballast water in this area. [ABSTRACT FROM AUTHOR]