Similar Ones Are Not Related and Vice Versa—New Dendronotus Taxa (Nudibranchia: Dendronotidae) from the North Atlantic Ocean Provide a Platform for Discussion of Global Marine Biodiversity Patterns

One new species of the genus Dendronotus (Nudibranchia: Dendronotidae) is described from Norway and Northern Ireland, as well adjacent North Sea, one subspecies arcticus by applying a combination fine-scale morphological molecular phylogenetic data. The present case demonstrates multilevel similarities differences considering on hand grouping three similar looking sympatric taxa (D. yrjargul, D. gartensis n. subsp. keatleyae sp.), other two different apparently allopatric subsp.). type genus, frondosus, which commonest dendronotid in United Kingdom, consistently substantial sp. study, apart providing purely taxonomic information, also provides data for broad discussion global biodiversity patterns.