Genetic barcoding confirms the presence of the neurotoxic sea slug Pleurobranchaea maculata in southwestern Atlantic coast

This work extends a previous report on the outbreak of an unknown neurotoxic sea slug along the southwestern Atlantic coast by providing identification to species level. In this study a c. 550 base pair (bp) region of the cytochrome c oxidase subunit 1 mitochondrial gene used for genetic barcoding was sequenced from three individual slugs sourced from three locations in Argentina. These data, in concert with previous description on the morphology and the presence of a neurotoxin of similar effect of that produced by pleurobranchs from New Zealand, confirm the identity of these sea slugs as Pleurobranchaea maculata. This is the first record of the species in the Atlantic Ocean, thus suggesting an exotic origin. Given the fast spread of reports in the southwestern Atlantic (c. 2000km of coastline in 6 years) we recommend urgent studies to determine the origin, toxicity, population genetics and impacts on local ecosystems.