Large-scale megabarcoding using Oxford Nanopore Technology enables fine-scale mapping of Terebellides (Annelida, Trichobranchidae) in Sweden with the description of two new species

Species of the genus Terebellides (Annelida, Trichobranchidae) are common and abundant in marine benthic communities. They are also morphologically homogeneous, and molecular studies have revealed the presence of many undescribed species in the North-East Atlantic. This can hinder accurate environmental monitoring. In the Skagerrak and Kattegat, ten species have been previously detected based on molecular analyses. However, the number of species occurring in Swedish waters, their distributions and relative abundance are unclear.To resolve these questions, a total of 521 specimens of Terebellides were gathered for molecular analyses. To analyse such a large dataset, two methods were used and compared. The first one used individual Sanger sequencing to obtain a 313 bp fragment of the COI marker. The second method combined tagged primers and multiplexed sequencing with Oxford Nanopore Technology (ONT). A total of 191 sequences were obtained with Sanger sequencing and 413 sequences with ONT, demonstrating the advantage of the latter method for this type of dataset. Six species were found, including Terebellides europaea, T. lavesquei, T. shetlandica and T. williamsae and new specimens of two species that had previously been detected but remained undescribed. They are here described as Terebellides agreniusi sp. nov. and Terebellides nevmyanovi sp. nov.LSID for the publication: urn:lsid:zoobank.org:pub:9D13BD18-9D25-4327-8139-F46273449BD9LSID for T. agreniusi: urn:lsid:zoobank.org:act:012F26B8-D297-4F43-9F45-33230BE1B158LSID for T. nevmyanovi: urn:lsid:zoobank.org:act:261E60E9-265F-457A-BE43-ADFF995A9C3A