Hydroides dianthus (Polychaeta: Serpulidae), an alien species introduced into Tokyo Bay, Japan
An example is given of a species recently introduced into Tokyo Bay, central Japan, probably from European or American waters. Empty calcareous tubes and living specimens of the serpulid polychaete Hydroides dianthus (Verrill, 1873) were found on monitoring test panels immersed near Ichikawa, Tokyo Bay, in 2006, together with its congeners H. ezoensis, H. exaltatus and H. fusicolus. The species of North American origin is now common in Europe, West Africa and the Mediterranean. We discuss its origin, vector, source of introduction and possible impact.