Cirratulidae is a group of common marine benthic annelids with about 397 nominal species described worldwide, 58 of which are reported in European waters. Due to the general morphological homogeneity among species from several genera, this group is considered difficult to identify to species level, has a complex taxonomical and nomenclatural history and is largely understudied. The aim of this study was to assess the species d...

The importance of identifying biological diversity accurately and efficiently is becoming more evident. It is therefore critical to determine the species boundaries between closely related taxa and to establish diagnostic characters that allow us to define species. This is not an easy task when species exhibit high intraspecific phenotypic plasticity or when distinct evolutionary lineages with an unusually large amount of gene...