A synoptic review of the family Dendronotidae (Mollusca: Nudibranchia): a multilevel organismal diversity approach

Abstract

A synoptic review of the family Dendronotidae is presented based on morphological and molecular data. Three genera are recognized: Dendronotus, Pseudobornella, and Cabangus gen. nov. Two new Dendronotus species are described, D. yrjargul sp. nov. and D. nordenskioeldi sp. nov., which reveal fine-scale differences. Dendronotus yrjargul sp. nov. from mid-Norway and the Arctic regions is a sister species to the North Pacific D. kalikal. These two species are showing clear morphological and ontogenetic differences but are close in genetic distance. In contrast, Dendronotus nordenskioeldi sp. nov. from the Laptev Sea is externally similar to the white morphs of D. lacteus or D. frondosus, but according to the molecular data and radular morphology it is distinct from any of its congenerics. Comparison of molecular and morphological data of D. niveus from the type locality (White Sea) and material from other localities with those from the American North Atlantic coast (type locality of D. elegans) reveals their substantial similarity. Therefore, D. niveus is considered a junior synonym of D. elegans. The present review of the family Dendronotidae contributes to a general discussion on the species concepts and on a recent proposal of multilevel organismal diversity.

Biodiversity hotspot in cold waters: a review of the genus Cuthonella with descriptions of seven new species (Mollusca, Nudibranchia)

“…This suggests a case of allopatric speciation between the North Atlantic C. concinna concinna and its sister NE Pacific subspecies C. concinna bellatula subsp. nov. Allopatric speciation has previously been well documented from various species of nudibranchs (e.g., Korshunova et al, 2018bKorshunova et al, , 2020a. The reasons why the biodiversity hotspot for cuthonellids in the Middle Kuril Islands has not been recognised before can be explained by both insufficient sampling and a deficit of taxonomic reviews for this region.…”

“…22), which has no reliable morphological apomorphies (see discussion in Korshunova et al, 2017a). Only narrower, more finely defined taxa of genus-and family groups can be used to integrate morphological and molecular data (Korshunova et al, 2017b(Korshunova et al, , 2020a…”

“…However, for some groups of invertebrates biodiversity is higher in northern seas, e.g. in marine isopods (Poore & Bruce, 2012) or nudibranchs of the family Dendronotidae (Korshunova et al, 2020a). Here we report the unexpectedly high diversity of a genus of aeolidacean nudibranch molluscs in the waters of the North Pacific.…”

Consolidated data on the phylogeny and evolution of the family Tritoniidae (Gastropoda: Nudibranchia) contribute to genera reassessment and clarify the taxonomic status of the neuroscience models Tritonia and Tochuina

“…This proves necessity of a fine-scale distinguishing of the genera within the family Tritoniidae. The radular patterns of adult Marianina rosea highly resemble early juvenile teeth of other complex at adult stage tritoniids [ 78 , 79 ], and also species from the distantly related family Dendronotidae [ 80 , 81 ]. According to the molecular phylogenetic analysis ( Fig 1A ) Marianina with simple external morphology (narrow body with non-branched appendages, Figs 1A , 1B and 8 ) is a sister taxon to the tritoniid Tritoniopsis with a complex external morphology (broad body with strongly branched appendages).…”

“…For the notum following states are recognized (the details of codes on the figure): NA, notal edges are absent or weakly defined; NM, notal edges considerably modified (for example, into large separate lobes); NP, notal edges present, well-defined. Sources of the morphological data used for the character state coding are [1,2,25,47,73,81,86,90,93,117,127] and the present study. See also text for discussion.…”