Barroso, MaríaCapa, MaríaRavara, A.Moreira, JuanParapar, Julio2026-05-132026-05-132026-04-09Barroso, M., Capa, M., Ravara, A. et al. A new species of Lagis Malmgren, 1866 (Annelida; Pectinariidae) and revision of the type material of Lagis koreni. Mar. Biodivers. 56, 39 (2026). https://doi.org/10.1007/s12526-026-01640-61867-16241867-1616https://hdl.handle.net/2183/48235Financiado para publicación en acceso aberto: Universidade da Coruña/CISUG[Abstract] In this study, maximum likelihood phylogenetic analyses of molecular markers (two mitochondrial genes—COI and 16S rRNA) confirmed that Lagis koreni Malmgren, 1866 represents in fact two distinct and well-supported species lineages. Examination of individuals collected on the West coast of Sweden, North of Norway, Northwest Spain, and North of Portugal allowed to morphologically characterise these two lineages. Consequently, Lagis koreni is redescribed based on type material, and a new species named Lagis depende sp. nov. is formally described. The size and number of the crenulations of the anal flap are revealed as main discriminant characters. The lectotype of L. koreni was revised and identified to belong to Cistenides hyperborea Malmgren, 1866 and a new lectotype for L. koreni is therefore tentatively proposed. Individuals of Amphictene auricoma (O.F. Müller, 1776) were also included in the molecular analyses resulting in a well-delineated lineage.engAttribution 4.0 Internationalhttp://creativecommons.org/licenses/by/4.0/DNA species delimitationIntegrative taxonomyNortheast AtlanticPolychaetesSEMjournal articleopen access10.1007/s12526-026-01640-6