Dna barcoding reveals unexpected diversity of deep-sea octopuses in the north-east atlantic

The taxonomy of Bathypolypus and Muusoctopus has long been confounded by poor original de¬scriptions and difficulty in distinguishing among species morphologically. We aimed to use DNA barcoding in conjunction with species delimitation techniques and morphological identification of mature males to identify the species of Bathypolypus and Muusoctopus present in the North-east Atlan¬tic and provide additional information on species distributions. From 298 specimens collected during biannual Deepwater Timeseries cruises and other aligned surveys undertaken by Marine Scotland onboard MRV Scotia between 2005–19, we identified Bathypolypus arcticus, B. ergasticus, B. bairdii, B. sponsalis, B. pugniger, Muusoctopus normani and M. johnsonianus as well as an unidentified Muusoctopus species that we conclude is likely to be a new species. We show the utility of DNA barcoding in identifying difficult to distinguish species such as deep-sea octopuses. Studies like ours are essential to provide clarity on the taxonomy of such groups and to determine the true diversity and distribution of species within them.