Unveiling a hidden wanderer in the NE Atlantic: a new species of Scalibregma (Annelida, Scalibregmatidae)

During a biodiversity survey conducted in the Bay of Biscay (Northeast Atlantic Ocean, France) within the framework of offshore wind energy development, a new species of Scalibregma was identified. This species is morphologically and genetically (16S rDNA and COI) characterized, and compared with its nearest congeners. A key for Scalibregma species with branchiae from chaetigers 3 to 5 and DNA sequences for S. celticum Mackie, 1991 and S. inflatum Rathke, 1843 occurring in the same area, are provided as well.

Based on molecular phylogenetic analysis using the COI gene, S. celticum is found as sister species of S. drouali sp. nov. Morphologically, the new species is closest to S. stenocerum (Bertelsen & Weston, 1980), but it differs by having a distinct mid-ventral row with large (double) epidermal pads and the presence of hirsute capillaries instead of inconspicuous mid-ventral line and only smooth capillaries as observed in S. stenocerum.

The new species potentially occurs from Atlantic French coast (Bay of Biscay) to Moroccan coast between 55 to 104 m depth.