Molecular identification of Didemnum vexillum Kott, 1982 from sites around the UK coastline

Didemnum vexillum Kott, 1982 is a tunicate known as the carpet sea squirt that is non-native to the UK. It has been reported from sites in the UK and Ireland based on morphological characteristics. Here we present the results of Cytochrome Oxidase I mitochondrial gene analyses to confirm species identification of specimens taken from several of the sites around the UK mainland coast where non-native tunicate colonies have been reported. The results confirm the identity of the UK carpet sea squirt samples as Didemnum vexillum and provide additional information on COI haplotypes present in the UK.