Toward an atlas of Salish Sea biodiversity: the flora and fauna of Galiano Island, British Columbia, Canada. Part I. Marine zoology.

Background: Based on records dating from 1859 to 2021, we provide an overview of the marine animal diversity reported for Galiano Island, British Columbia, Canada. More than 650 taxa are represented by 20,000 species occurrence records in this curated dataset, which includes dive records documented through the Pacific Marine Life Surveys, museum voucher specimens, ecological data and crowd-sourced observations from the BC Cetacean Sightings Network and iNaturalist. New information: We describe Galiano Island's marine animal diversity in relation to the Salish Sea's overall biodiversity and quantify the proportional contributions of different types of sampling effort to our current local knowledge. Overviews are provided for each taxonomic group in a format intended to be accessible to amateur naturalists interested in furthering research into the region's marine biodiversity. In summary, we find that the Pacific Marine Life Surveys, a regional community science diving initiative, account for 60% of novel records reported for Galiano Island. Voucher specimens account for 19% and crowd-sourced biodiversity data 18% of novel records, respectively, with the remaining 3% of reports coming from other sources. These findings shed light on the complementarity of different types of sampling effort and demonstrate the potential for community science to contribute to the global biodiversity research community. We present a biodiversity informatics framework that is designed to enable these practices by supporting collaboration among researchers and communities in the collection, curation and dissemination of biodiversity data.

Three new species of the genus Dendronotus from Japan and Russia (Mollusca, Nudibranchia).

Three new species of the genus Dendronotus are described from the North Pacific waters of Japan and Russia. For the first time since 1949, three new species, D. jamsteci sp. nov., D. zakuro sp. nov. and D. bathyvela sp. nov. are described from the waters of the Japanese Islands. D. zakuro sp. nov. was also discovered in the waters of Russia (Kamchatka). The descriptions of the new species D. jamsteci sp. nov. and D. zakuro sp. nov. are based on morphological and molecular data; D. bathyvela sp. nov. morphologically belongs to the group of D. robustus, D. velifer and D. patricki. This study revises our knowledge of North Pacific species of the genus Dendronotus, considerably expands the number of species worldwide and contributes to the multilevel fine-scale diversity concept.

Fine-scale species delimitation: speciation in process and periodic patterns in nudibranch diversity.

Using the nudibranch genus Amphorina as a model, ongoing speciation is demonstrated, as well as how periodic-like patterns in colouration can be included in an integrated method of fine-scale species delimitation. By combining several methods, including BPP analysis and the study of molecular, morphological, and ecological data from a large number of specimens within a broad geographic range from northern Europe to the Mediterranean, five species are recognised within the genus Amphorina, reviewed here for the first time. Two new species from the southwestern coast of Sweden are described, A. viriola sp. nov. and A. andra sp. nov. Evidence is provided of a recent speciation process between the two closely related, yet separate, species which inhabit the same geographic localities but demonstrate strict water depth differentiation, with one species inhabiting the shallow brackish top layer above the halocline and the other species inhabiting the underlying saltier water. The results presented here are of relevance for currently debated issues such as conservation in relation to speciation, fine species delimitation, and integration of molecular, morphological and ecological information in biodiversity studies. The periodic approach to biological taxonomy has considerable practical potential for various organismal groups.

Multiple paedomorphic lineages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella.

Paedomorphosis is an important evolutionary force. It has previously been suggested that a soft-substrate sediment-dwelling (infaunal) environment facilitates paedomorphic evolution in marine invertebrates. However, until recently this proposal was never rigorously tested with robust phylogeny and broad taxon selection. Here, for the first time, we present a molecular phylogeny for a majority of the 21 families of one of the largest nudibranch subgroups (Aeolidacea) and show that the externally highly simplified vermiform nudibranch family, Pseudovermidae, with clearly defined paedomorphic traits and inhabiting a soft-substrata environment, is a sister group to the complex nudibranch family, Cumanotidae. We also report the rediscovery of one of the most enigmatic nudibranchs-Xenocratena suecica-on the Swedish and Norwegian coasts 70 years after it was first found. Xenocratena was described from the same location and environment in the Swedish Gullmar fjord as one of the most enigmatic vermiform organisms, Xenoturbella bocki, which represents either an original simple bilaterian body plan or secondary simplification of a more complex organisation. Our results show that Xenocratena suecica reveals an onset of parallel paedomorphic evolution so we have proposed the new family, Xenocratenidae fam. n., to accommodate the molecular and morphological disparities we discovered. The paedomorphic origin of another aeolidacean family, Embletoniidae, is also demonstrated for the first time. Thus, by presenting three independent lineages from non-closely related aeolidacean families, Xenocratenidae fam. n., Cumanotidae and Embletoniidae, we confirm with phylogenetic data that a soft-substrata burrowing-related environment strongly favours paedomorphic evolution. We suggest criteria to distinguish ancestral and derived characters in the context of modifications of ontogenetic cycles. Applying an evolutionary model of the soft substrate-driven multiple paedomorphic origin of several families of nudibranch molluscs we propose that it is plausible to extend this model to other marine invertebrates and suggest that the ancestral organisation of the enigmatic metazoan, Xenoturbella, might correspond to the larval part of a complex ancestral bilaterian ontogenetic cycle with sedentary/semi-sedentary adult stages and planula-like larval stages.

Multilevel fine-scale diversity challenges the 'cryptic species' concept.

'Cryptic' species are an emerging biological problem that is broadly discussed in the present study. Recently, a cryptic species definition was suggested for those species which manifest low morphological, but considerable genetic, disparity. As a case study we present unique material from a charismatic group of nudibranch molluscs of the genus Trinchesia from European waters to reveal three new species and demonstrate that they show a dual nature: on one hand, they can be considered a 'cryptic' species complex due to their overall similarity, but on the other hand, stable morphological differences as well as molecular differences are demonstrated for every species in that complex. Thus, this species complex can equally be named 'cryptic', 'pseudocryptic' or 'non-cryptic'. We also present evidence for an extremely rapid speciation rate in this species complex and link the species problem with epigenetics. Available metazoan-wide data, which are broadly discussed in the present study, show the unsuitability of a 'cryptic' species concept because the degree of crypticity represents a continuum when a finer multilevel morphological and molecular scale is applied to uncover more narrowly defined species making the 'cryptic' addition to 'species' redundant. Morphological and molecular methods should be applied in concordance to form a fine-scale multilevel taxonomic framework, and not necessarily implying only an a posteriori transformation of exclusively molecular-based 'cryptic' species into morphologically-defined 'pseudocryptic' ones. Implications of the present study have importance for many fields, including conservation biology and fine-scale biodiversity assessments.

The genus Zelentia is an amphi-boreal taxon expanded to include three new species from the North Pacific and Atlantic oceans (Gastropoda: Nudibranchia: Trinchesiidae).

The taxonomy of Zelentia Korshunova, Martynov Picton, 2017, a genus of aeolidacean nudibranchs recently separated from Trinchesia Ihering, 1879, is reviewed. Using previous and novel data, including the defining morphological characters of a supplementary gland inserted into the penis, which is also armed with stylet, it is demonstrated that the genus Zelentia is a well-established amphi-boreal taxon. A phylogenetic tree and haplotype network for species of the genus Zelentia are provided. A new species from the Northeastern Pacific, Zelentia willowsi sp. nov. and a second Northeastern Pacific species, Zelentia nepunicea sp. nov., previously thought to be "Cuthona" pustulata (Alder Hancock, 1854), are described using morphological and molecular data. A new species from the North Atlantic and sub-Arctic White Sea, Zelentia roginskae sp. nov., is also described using morphological and molecular data. The Northeastern Pacific Zelentia nepunicea sp. nov. and"Cuthona" punicea Millen, 1986, which externally share a similar reddish colouration, are shown to belong to two different families since "Cuthona" punicea possesses a supplementary gland inserted into the vas deferens and an unarmed penis, characters of the genus Cuthonella Bergh, 1884, belonging to the Cuthonellidae family. Despite belonging to different families and having significant internal differences, externally Cuthonella punicea and Zelentia nepunicea sp. nov. appear similar, thus the new sympatric species of Zelentia is given the name Z. nepunicea sp. nov. which means non punicea. To facilitate identification and avoid further confusion we provide a comparative table which encompasses diagnostic morphological data for Northeastern Pacific species of the families Cuthonidae, Cuthonellidae and Trinchesiidae which are externally similar to the described new taxa.

Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda).

The Flabellinidae, a heterogeneous assembly of supposedly plesiomorphic to very derived sea slug groups, have not yet been addressed by integrative studies. Here novel material of rarely seen Arctic taxa as well as North Atlantic, North and South Pacific, and tropical Indo-West Pacific flabellinid species is investigated morpho-anatomically and with multi-locus markers (partial COI, 16S rDNA, 28S rDNA and H3) which were generated and analysed in a comprehensive aeolid taxon sampling. It was found that the current family Flabellinidae is polyphyletic and its phylogeny and taxonomic patterns cannot be understood without considering members from all the Aeolidacean families and, based on a robust phylogenetic hypothesis, morpho-anatomical evolution of aeolids is more complex than suspected in earlier works and requires reclassification of the taxon. Morphological diversity of Flabellinidae is corroborated by molecular divergence rates and supports establishing three new families (Apataidae fam. n., Flabellinopsidae fam. n., Samlidae fam. n.), 16 new genera, 13 new species, and two new subspecies among the former Flabellinidae. Two families, namely Coryphellidae and Paracoryphellidae, are restored and traditional Flabellinidae is considerably restricted. The distinctness of the recently described family Unidentiidae is confirmed by both morphological and molecular data. Several species complexes among all ex-"Flabellinidae" lineages are recognised using both morphological and molecular data. The present study shows that Facelinidae and Aeolidiidae, together with traditional "Tergipedidae", deeply divide traditional "Flabellinidae." Diagnoses for all aeolidacean families are therefore provided and additionally two new non-flabellinid families (Abronicidae fam. n. and Murmaniidae fam. n.) within traditional tergipedids are established to accommodate molecular and morphological disparity. To address relationships and disparity, we propose a new family system for aeolids. Here the aeolidacean species are classified into at least 102 genera and 24 families. Operational rules for integration of morphological and molecular data for taxonomy are suggested.

Corrigenda: Polyphyly of the traditional family Flabellinidae affects a major group of Nudibranchia: aeolidacean taxonomic reassessment with descriptions of several new families, genera, and species (Mollusca, Gastropoda). https://doi.org/10.3897/zookeys.717.21885.

[This corrects the article DOI: 10.3897/zookeys.717.21885.].

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

Two new species of the nudibranch genus Dendronotus, Dendronotus arcticussp. n. and Dendronotus robilliardisp. 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 robilliardisp. 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 arcticussp. 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.