A new record of Ascidiella scabra (Müller, 1776) (Ascidiacea, Phlebobranchia) in the southwestern Atlantic

Non-indigenous ascidians are transported across oceans in vessel-hull fouling communities, and regional traffic plays a role in their secondary spread. We found the ascidian Ascidiella scabra (Müller, 1776) in the hull-fouling community of an oceanographic vessel confined to waters of the southwestern Atlantic and Southern Oceans. The previously known distribution of this species was restricted to its native area (Mediterranean Sea and northeastern Atlantic); its presence in the southwestern Atlantic may have been masked in the past by the occurrence of its congener Ascidiella aspersa (Müller, 1776).