A further step towards the characterisation of Terebellides (Annelida, Trichobranchidae) diversity in the Northeast Atlantic, with the description of a new species

Several new species of genus Terebellides Sars, 1835 (Annelida, Trichobranchidae) have been recently described from the Northeast Atlantic Ocean after the detection of a large complex of species based on DNA sequence data from previous research. Some of those species (belonging to the so-called Group A) have already been described elsewhere. In this paper, we revise several Terebellides clades belonging to Groups B, C and D resulting in the identification of five nominal species: Terebellides gracilis Malm, 1874, Terebellides atlantis Williams, 1984, Terebellides williamsae Jirkov, 1989, Terebellides irinae Gagaev, 2009, and Terebellides shetlandica Parapar, Moreira & O’Reilly, 2016, plus one new species described here as Terebellides lavesquei sp. nov. All these species are characterised by a combination of morphological features complemented with a nucleotide diagnostic approach (specific COI nucleotides in the alignment position). Morphological characters used to discriminate between taxa refer to the branchial shape, presence/absence of ciliated papillae dorsal to thoracic notopodia and the morphology of thoracic and abdominal uncinal teeth. An updated identification key to all described species of this genus in NE Atlantic waters is also includedThis study was partly supported by the FAUNA IBÉRICA research project Polychaeta VII, Palpata, Canalipalpata II (PGC2018–095851–B–C64) funded by the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación, and coordinated by JP. Funding was also provided from the Ramón y Cajal program (RYC-2016- 20799) funded by Spanish MINECO, Agencia Estatal de Investigación, Comunidad Autónoma de las Islas Baleares and the European Social Fund to MC. Financial support was also provided by the Norwegian Taxonomy Initiative: Cryptic polychaete species in Norwegian waters, knr 49-13, project no. 70184228 to AN; Polychaetes in the Norwegian Sea, project no. 70184227; Polychaetes in Skagerrak, project no.70184216; and the MAREANO program. We are deeply grateful to the reviewers of the manuscript, Pat Hutchings and Nicolas Lavesque, as well as Greg Rouse, ZooKeys Subject Editor and Nathalie Yonow, ZooKeys Copy Editor, for their constructive suggestions, which greatly improved the quality of the manuscript. We also thank Yordanka Banalieva and Tsvetelina Milenkova for their valuable help in the efficient manuscript editorial and accounting management processe