Whole-genome sequencing suggests taxonomic inflation in the Careproctus snailfishes (Liparidae) of the northeast Atlantic–Arctic region

As Arctic Ocean temperatures rise, the composition and distribution of fish species are changing. A clear and accurate classification of species is therefore instrumental to the conservation and management of this region. Careproctus snailfishes (Liparidae) are common in the region, but suffer from controversial taxonomy, relying on morphological characters that are difficult to study due to fragile skin, soft bodies, and poorly ossified skeletons. In the present study, we provide a screening of the Careproctus species diversity in the northeast Atlantic and adjacent Arctic region. Using a combination of mitochondrial DNA and nuclear SNP data, we evaluate the taxonomic validity of certain proposed species, distinct from C. micropus and C. reinhardti. Our findings provide minimal support for more than these two species. Since the species unit forms the foundation for biodiversity research and communication, we highlight the importance of reliable and established morphological traits in taxonomy. We recommend supplementing morphology with genetic methods to minimize the risk of taxonomic inflation, especially in rare or understudied taxa. Furthermore, we confirm the occurrence of C. micropus from a coastal fjord system in northern Norway, extending its known distribution.