Increased information on biodiversity from the neglected part of the North Pacific contributes to the understanding of phylogeny and taxonomy of nudibranch molluscs

Abstract

Understanding of the biological diversity, involving molecular phylogenetic methods, is a fundamental task for a broad array of evolutionary, taxonomic, and ecological studies, as well as a basis for conservation. Our hydrobiological survey during an expedition in 2021 to the coastal waters of the Kuril Islands (the northwestern Pacific) revealed the undocumented diversity of the nudibranch molluscs. Two new species of the genera Zelentia and Cuthonella are described here using analysis of fine-scale morphological and molecular data. Representatives of the genus Zelentia prior to this study were known only from the North Atlantic and from the Canadian and US northeastern Pacific. In addition, two new distributional records of the previously described species Cuthonella denbei Korshunova et al., 2020 and Cuthonella soboli Martynov, 1992 are presented here for the first time. The molecular phylogenetic framework for the majority of the species of the genera Cuthonella and Zelentia, including the two new species, confirmed the taxonomic distinctness of the genus Zelentia (family Trinchesiidae) and the genus Cuthonella (family Cuthonellidae), and represents another important result of this study.