Two new species and a remarkable record of the genus Dendronotus from the North Pacific and Arctic oceans (Nudibranchia)

Abstract

Two new species of the nudibranch genus Dendronotus, Dendronotus arcticus sp. n. and Dendronotus robilliardi sp. n., are described from the Arctic and North Pacific oceans respectively, based on morphological and molecular data, and the North Pacific Dendronotus albus is revealed to be a species complex. The species Dendronotus robilliardi sp. n. is described from the northwestern Pacific (Kamchatka) differing from the northeastern Pacific Dendronotus albus by molecular and morphological data. The synonymy of Dendronotus diversicolor with Dendronotus albus is confirmed by analysis of their original descriptions. An endemic Arctic species Dendronotus arcticus sp. n. is also described here, differing substantially from all species of the genus Dendronotus using morphological and molecular data. An unusual record of the recently described Dendronotus kamchaticus Ekimova, Korshunova, Schepetov, Neretina, Sanamyan, Martynov, 2015 is also presented, the first from the northeastern Pacific, geographically separated from the type locality of this species in the northwestern Pacific by a distance ca. 6000 km; molecular data show them to belong to the same species.

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

“…Figure 4A-F. Dendronotus arcticus Korshunova et al 2016 [22] (pp. 26-28), Figures 1 and 3; Korshunova et al 2020 [23] (p. 21), Figure 7.…”

“…There are fine morphological differences between these taxa in the numbers of dorsolateral and oral veil appendages, as well as details of the central radular teeth (Figure 4). Dendronotus arcticus arcticus ranges from the core of the Arctic region [22], including the Laptev and Kara Seas, to the easternmost part of the Barents Sea adjacent to the Kara Sea. By contrast, D. arcticus gartensis n. subsp.…”

“…has translucent basal colouration, spinose dorsolateral appendages with golden-yellow upper parts and bright yellow spots on the dorsal side (Figure 4G,I,O,P). There are also potential fine-scale morphological differences between these subspecies internally in the relatively greater number of denticles on the rachidian teeth, copulatory organ and shape of the ampulla, and the number of prostatic alveoles (Figure 2B [22]).…”

“…Moreover, in recent years further and previously undetected diversity has been documented from Norway, the United Kingdom and neighbouring northern European localities [13][14][15][16][17][18]. A particular focus in recent years in connection with these biodiversity studies has been the family Dendronotidae and genus Dendronotus Alder and Hancock, 1845, which includes common shallow water species and for which a series of major revisions including the description of several new species has been conducted [19][20][21][22][23][24]. A new species of Dendronotus that spans both insular Europe (the United Kingdom) and European continent (Norway) was recently described as D. europaeus [25].…”

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

“…In the check-list of free living marine invertebrates of the Far Eastern seas of Russia, twenty two species are mentioned for the southern Kurile Islands and southern Sakhalin [Martynov, 2013], however the exact geographical range of species across this region is not clear. Scarce information on the Sakhalin nudibranch fauna is exceptionally low in comparison to the well-studied and rich biodiversity of the Sea of Japan [Baba, 1960;1961;Martynov, Roginskaya, 2005;Martynov et al, 2015a, b;Ekimova et al, 2016;2021b;2022b;Korshunova et al, 2023a], Kurile Islands [Martynov et al, 2015 a,b;Korshunova et al, 2020a,b;Martynov, Korshunova, 2020;2022;Ekimova et al, 2021a; and Kamchatka [Martynov et al, 2009;2015a, b;Korshunova et al, 2016].…”