The non-indigenous stolidobrach ascidian Polyandrocarpa zorritensis in the Mediterranean: description, larval morphology and pattern of vascular budding

The stolidobranch ascidian Polyandrocarpa zorritensis was detected, for the third time in the Mediterranean, in the harbour of Taranto (South Italy). Colonies develop vigorously on all hard substrata in shallow water and now represent one of the most important elements of the local fouling community. In this article specimens of the Mediterranean populations of the species are described. The morphology of the larva, which differs from that of other Polyzoinae, and a vascular budding mechanism of replication, similar to that known to occur in the Botryllinae, were both observed for the first time.