Still Many to Be Named: An Integrative Analysis of the Genus Dendronotus (Gastropoda: Nudibranchia) in the North Pacific Revealed Seven New Species

Abstract

In this paper, we report on the discovery of the hidden biodiversity of the genus Dendronotus (Gastropoda: Nudibranchia) in bathyal areas of the North Pacific (the Sea of Okhotsk and the Kuril Islands). We also test different scenarios of Dendronotus expansion to deeper waters. An integrative analysis was implemented based on morphological data (light microscopy and SEM) and molecular data, which included molecular phylogenetic analysis of four markers (COI, 16S, H3, and 28S), molecular species delimitation analyses, and ancestral area reconstruction. Our results indicated the presence of seven species new to science, five of which are described herein. The phylogenetic reconstructions show that these new species are members of different Dendronotus lineages. Ancestral area reconstruction indicates the shallow-water origin of the genus, while the invasion of deep waters occurs independently multiple times.