A report of a new species and new record of Cadlina (Nudibranchia, Cadlinidae) from South Korea

Abstract

Of the four species in the genus Cadlina present in the northwestern Pacific region, C. japonica has been the only species recorded from South Korea. For the purpose of investigating Cadlina in Korean waters, specimens were collected from the Korean East Sea (Sea of Japan) by scuba diving. The radula and morphology of these specimens were examined by stereoscopic and scanning electron microscopy. Based on morphology, three species were identified in Korean waters, including the new species, Cadlina koreanasp. nov., C. umiushi (first record in South Korea), and C. japonica. Cadlina koreanasp. nov. somewhat resembles C. umiushi but differs in both its morphology as well as the structure of its radula. The background color of Cadlina koreanasp. nov. is translucent white, tubercles on the dorsum are opaque white and the yellow marginal band is absent. The radular formula of Cadlina koreanasp. nov. is 57 × 23.1.23 with a rectangular rachidian tooth. In addition, mitochondrial cytochrome c subunit 1 (COI), 16S ribosomal RNA (16S rRNA), and nuclear 28S ribosomal RNA (28S rRNA) gene sequences were generated and used for analysis of Automatic Barcode Gap Discovery (ABGD) and reconstruction of the phylogenetic tree. Morphological distinction and genetic analyses confirm that three Cadlina species are present in Korean waters of which Cadlina koreana is a new species.

Nudibranch molluscs of Sakhalin Island, Northwestern Pacific: new records and descriptions of two new species

“…Spokoinaya Bay, Rudnaya Bay [Martynov et al, 2015a,b;Korshunova et al, 2020a;Chichvarkhin, 2016]. It was discovered further south, in the Sea of Japan waters of South Korea [Do et al, 2020]. Our results extend the geographical range of this species to southern parts of the Sea of Okhotsk (Aniva Bay).…”

“…In the case of the genera Cadlina, Adalaria, Onchimira, and Cuthonella phylogenetic reconstructions were performed. For this purpose, we incorporated in our analyses molecular datasets obtained in previous studies: Cadlina [Korshunova et al, 2020b;Do et al 2020;Ekimova et al, 2021a]; Adalaria and Onchimira [Hallas et al, 2017]; Cuthonella [Korshunova et al, 2020b]. For the rest of the biodiversity only a BLAST-n search was done.…”

The Phyloperiodic Approach Removes the “Cryptic Species” and Puts forward Multilevel Organismal Diversity

“…nov., and C. bellburnellae sp. nov.), as well as the previously described Cadlina laevis, C. kamchatica [32], C. koreana (external and radular drawings on Figures 2-4 for the latter species are based on [72]), C. paninae, and C. umiushi [32] based on the shape of copulative spines (Figures 5 and 12(A13-A15)). However, the radular morphology (central teeth) and external features of C. vinogradovi sp.…”

Validating a molecular clock for nudibranchs—No fossils to the rescue

“…The discovery of a new species of nudibranch adds to a recent body of work employing molecular data to propel species discovery in this diverse group of invertebrates (e.g. Do et al., 2020 ; Epstein et al., 2019 ; Matsuda & Gosliner, 2018 ), but the nudibranch fauna of the western Atlantic has been less well studied than the Indo‐Pacific.…”

“…Bertsch noted that the reproductive system was identical to that illustrated in the original description of C. sedna (Marcus & Marcus, 1967) and that the radular morphology matched the holotype, and fell within the range for specimens described from the Gulf of California (Bertsch, 1978). Overall, he did not consider these slight morpho- Do et al, 2020;Epstein et al, 2019;Matsuda & Gosliner, 2018), but the nudibranch fauna of the western Atlantic has been less well studied than the Indo-Pacific.…”