First record of the non-indigenous ascidian Microcosmus exasperatus, Heller 1878, in Cyprus

The solitary ascidian Microcosmus exasperatus (Class: Ascidiacea, Family: Pyuridae) is found in both tropical and sub-tropical waters. In the Mediterranean it has been recorded on the coasts of Israel, Lebanon, Turkey, and Tunisia. Here we report its first record from Cyprus, where it was found forming aggregations on ropes in a marina. It was also recorded there on the hull of a 7-meter pleasure craft. We provide both molecular and morphological diagnostics to facilitate the accurate identification of M. exasperatus, as its external appearance resembles that of M. squamiger, which is a widely-distributed species in the western Mediterranean. The occurrence of M. exasperatus on ship hulls and its ability to form large aggregations on artificial substrata may accelerate introduction of the non-native epifaunal organisms that cover its tunic, consequently altering local biodiversity. Thus, we strongly recommend monitoring the progression of this invasive species in the eastern Mediterranean.