Genetic similarity between Boccardia proboscidea from Western North America and cultured abalone, Haliotis midae, in South Africa

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South African cultured abalone, Haliotis midae, are commonly infested by the non-indigenous spionid polychaete, Boccardia proboscidea. This annelid species occurs naturally along the west coast of North America and around Japan, but has also been introduced in Hawaiʻi, Australia, New Zealand and perhaps the Iberian Peninsula. Reportedly, worms were inadvertently transported to South Africa on Haliotis rufescens imported from California in the late 1980s. To test this hypothesis, populations from six abalone farms on the west, south and east coasts of South Africa were compared with populations from California (Alamitos Bay and La Jolla), Washington State (False Bay Harbour) and British Colombia (Vancouver Island). Sequence data of 16S rRNA and cytochrome b (Cyt b) mitochondrial genes show a genetic similarity between worms from South Africa and the west coast of North America with identical haplotypes for each gene found among these populations. The data also indicate that worms were spread among farms in South Africa primarily through the transport of infested abalone.