Molecular diversity within the genus <i>Laeonereis</i> (Annelida, Nereididae) along the west Atlantic coast: paving the way for integrative taxonomy

The polychaete genus Laeonereis (Annelida, Nereididae) occurs over a broad geographic range and extends nearly across the entire Atlantic coast of America, from USA to Uruguay. Despite research efforts clarify its diversity systematics, mostly by morphological ecological evidence, there is still uncertainty, mainly concerning species culveri , which constitutes an old notorious case taxonomic ambiguity. Here, we revised molecular distribution based on multi-locus approach, including DNA sequence analyses partial segments cytochrome c oxidase subunit I (COI), 16S rRNA, 28S rRNA genes. We examined specimens collected 26 sites along American Massachusetts (USA) Mar del Plata (Argentina). Although no comprehensive examination was performed between different populations, COI barcodes revealed seven highly divergent MOTUs, with mean K2P genetic distance 16.9% (from 6.8% 21.9%), confirmed through four clustering algorithms. All MOTUs were geographically segregated, except for 6 7 southeastern Brazil, presented partially overlapping ranges Rio de Janeiro São Paulo coast. Sequence data obtained markers supported same MOTU delimitation segregation as those COI, providing further evidence existence deeply lineages within genus. extent divergence observed in our study fits comfortably reported polychaetes, Nereididae, thus strong indication that they might constitute separate species. These results may therefore pave way integrative studies, aiming status herein reported.