Six new species of Macellicephala (Annelida: Polynoidae) from the Southern Ocean and south Atlantic with re-description of type species

<p>Increased sampling efforts in unexplored regions of the Southern Ocean (including depths >500 m) combined with the use of an epibenthic sledge resulted in a large collection of mobile, scale-bearing worms from the family Polynoidae Kinberg, 1856. The greatest taxonomic novelty was found in the genus <em>Macellicephala</em> McIntosh, 1885, the type genus of the exclusively deep-sea polynoid sub-family Macellicephalinae Hartmann-Schröder, 1971. Recently collected material from the Amundsen Sea led to discovery of four new species based on morphology and COI, 16S and 18S genes—<em>Macellicephala gloveri</em> sp. nov., <em>M. linseae</em> sp. nov., <em>M. patersoni</em> sp. nov. and <em>M. brenesorum</em> sp. nov. The holotype of type taxon <em>Macellicephala mirabilis</em> McIntosh, 1885 as well as historic material of <em>Macellicephala</em> collected from the Southern Ocean enabled comparison with the modern material. As a result, <em>Macellicephala mirabilis </em>is re-defined, and two new species, <em>M. monroi</em> sp. nov. and <em>M. macintoshi</em> sp. nov., are erected from the historic material previously ascribed to <em>M. mirabilis</em>. Additionally, DNA-suitable specimens assigned to <em>M. monroi</em> sp. nov. were collected from the Scotia Sea. Genetic data enabled the first test of the monophyly of <em>Macellicephala</em>. Based on current taxa coverage, these taxa<em> </em>form a well-supported monophyletic group as recovered by Bayesian and Maximum Likelihood analyses of our combined genetic dataset. In addition, the analysis shows strong support of a clade comprising <em>Macellicephala</em> and other exclusively deep-sea groups (including cave-dwelling taxa).</p>