The taxonomy of aeolidacean nudibranchs the traditional group previously known as Tergipedidae is discussed. To integrate diverse molecular phylogenetic pattern and morphological disparity in a broadly ontogenetic context revised classification at family level presented. families Calmidae Iredale & O'Donoghue, 1923, Eubranchidae Odhner, 1934, Fionidae Gray, 1857 s. str. (restricted, with genus Fiona only), Bergh, 1889 s.str. inclusion Tergipes only) are restored. Cuthonidae 1934 only...

A new classification of Ophiuroidea, considering family rank and above, is presented. The superfamily taxa in O’Hara et al. (2017) were proposed to ensure a better readability the phylogeny but are unavailable under provisions ICZN. Here, morphological diagnoses all 33 families five superfamilies provided. Ten families, Ophiosphalmidae fam. nov., Ophiomusaidae Ophiocamacidae Ophiopteridae Clarkcomidae Ophiopezidae Ophiernidae Amphilimnidae Ophiothamnidae nov. Ophiopholidae described....

The taxonomy of Zelentia Korshunova, Martynov Picton, 2017, a genus aeolidacean nudibranchs recently separated from Trinchesia Ihering, 1879, is reviewed. Using previous and novel data, including the defining morphological characters supplementary gland inserted into penis, which also armed with stylet, it demonstrated that well-established amphi-boreal taxon. A phylogenetic tree haplotype network for species are provided. new Northeastern Pacific, willowsi sp. nov. second Pacific species,...

'Cryptic' species are an emerging biological problem that is broadly discussed in the present study. Recently, a cryptic definition was suggested for those which manifest low morphological, but considerable genetic, disparity. As case study we unique material from charismatic group of nudibranch molluscs genus Trinchesia European waters to reveal three new and demonstrate they show dual nature: on one hand, can be considered 'cryptic' complex due their overall similarity, other stable...

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

Most of the taxonomically reliable internal and microstructural characters (e.g. jaws, dental plate, genital plates, vertebrae) recent Ophiuroidea are studied using SEM on a broad comparative basis for first time, including examination arm spine articulation shape in 178 species from 105 genera 16 families encompassing all major ophiuroid generic diversity. Numerous taxonomic contradictions caused by “over-applying” external to traditional systematics found analyzed. Among newly applied...

The world’s most northern species of the nudibranch genus Adalaria rossica sp. nov. from Franz Josef Land and a new Onchidoris expectata north-west Pacific Matua Island (Kurile Islands) are described. Prior to this study fauna was represented only by two common North Atlantic species. Molecular taxonomic data were not applied for nudibranchs previously. Nudibranchs have never been investigated. Furthermore, taxon, ultima nov., is described here. taxonomy onchidoridid genera discussed.

A new species of calcareous sponge, Ernstia pyrum sp. nov. (Calcarea, Calcinea, Clathrinida, Clathrinidae) is described from marine reef aquarium. It assumed that its type locality Indonesia. Molecular data render this as a member the genus Ernstia, although morphology deviates in significant points original definition genus. In particular has clear atrial cavity not lined with choanocytes (true atrium), feature reported before for

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 rarely seen Arctic taxa as well North Atlantic, and South Pacific, tropical Indo-West Pacific flabellinid species is investigated morpho-anatomically with multi-locus markers (partial COI, 16S rDNA, 28S rDNA H3) which were generated analysed in comprehensive aeolid taxon sampling. It was found that the current family...

The taxonomy of common northern nudibranch molluscs the genus Dendronotus in vast cold regions Eurasia remains largely unknown. Abundant material collected many localities from Barents Sea, via Arctic region, to north-west Pacific was analysed for first time. An integrated approach combining morphological and ontogenetic data with molecular four-gene (COI, 16S, H3, 28S) analysis reveals seven species, including three previously undescribed. frondosus (Ascanius, 1774) dalli Bergh, 1879 were...

Cryptic species are an important concept of modern biodiversity studies and a potential basis for immensely increasing the amount biological diversity worldwide; however, conceptual grounds cryptic still need to be refined. Here, using remarkable example from marine invertebrates, case complex common large‐sized nudibranchs genus Dendronotus in European waters is presented, which relevant ongoing discussion. Based on extensive sampling seas Northern Hemisphere United Kingdom Sea Japan,...

Abstract Dorids are one of the largest nudibranch groups, encompassing more than 2000 species. One crucial problems with tracing evolution dorids is relationship between cryptobranch (gill cavity present) and phanerobranch absent). Integrative morphological molecular studies enigmatic Japanese dorid species genus Cadlina, C. japonica ‘C.’ sagamiensis, which were collected by Emperor Japan (Shōwa era), presented here for first time. It shown that while does belong to Cadlina clade, another...

Organismic diversity, as well distributional and ecological patterns, can be fully understood in an evolutionary framework only. Reliable phylogenetic trees are required to 'read history', but not yet available for most marine invertebrate groups. Molecular systematics offers enormous potential, still fails 'all-species approaches' on groups with species that rare or occur remote areas only, simply because there is no easily collectable material sequence analyses. Exploring morphologically...

The sea-grass borer Zachsia zenkewitschi belongs to a group of economically and ecologically important bivalves, commonly referred as shipworms. sole recognized representative the genus Zachsia, this species displays an unusual life history reproductive strategy that is now understood include: environmental sex determination free swimming larvae, extreme sexual size dimorphism between males females, internal fertilization, maintenance often large harems male dwarfs within specialized cavity...

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Heterochronic development has been proposed to have played an important role in the evolution of echinoderms. In class Ophiuroidea, paedomorphosis (retention juvenile characters into adulthood) documented families Ophiuridae and Ophiolepididae but not investigated on a broader taxonomic scale. Historical errors, confusing stages with paedomorphic species, show difficulties correctly identifying effects heterochrony evolution. This study presents detailed analysis 40 species morphologies...

A unique example of brackish water fjord-related diversification a new nudibranch genus and species Bohuslania matsmichaeli gen. n., sp. n. is presented. There are only few previously known brackish-water opisthobranchs B. the first ever described with such an extremely limited geographical range apparently strict adherence to salinity levels lower than 20 per mille. Up date taxon has been found in very restricted area Idefjord, bordering Sweden Norway, but not any other suitable localities...

Video surveys were carried out during the 75th cruise of RV Akademik M.A. Lavrentyev (June 2016) along northern slope Volcanologists Massif, in south-western Bering Sea. The seafloor was explored using ROV Comanche 18 . Seven dives performed depth range from 4,278 m to 349 m. Overall, about 180 species megafauna recognised. Fifteen types communities corresponding certain ranges distinguished based on most abundant taxa. Dominance changed with following order: holothurian Kolga kamchatica at...

Based on material from the fourth cruise of RV Akademik Mstislav Keldysh and MAR-ECO G.O. Sars, 31 species Ophiuroidea were identified section Mid-Atlantic Ridge between Reykjanes Azores. The taxonomy group genera with reduced arm comb tentacle pores restricted only to proximal segments is reviewed. It suggested that Homalophiura H.L. Clark, 1915, Ophiurolepis Matsumoto, Theodoria Fell, 1961 Homophiura Paterson, 1985 should be regarded as synonyms genus Ophioplinthus Lyman, 1878. From...

Nudibranch molluscs of the genus Corambe differ from most other Doridoidea by having ventral rather than dorsal anus and gills. Because these features, such as separate cerebral pleural ganglia, corambids have been considered an archaic or enigmatic group. The first tropical eastern Pacific species is described in morphological some histological detail. Selected organs circulatory central nervous features are reconstructed serial semithin slides visualized three dimensions using Amira...

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 molecular majority of 21 families one largest nudibranch subgroups (Aeolidacea) show externally highly simplified vermiform family,...

Using the nudibranch genus Amphorina as a model, ongoing speciation is demonstrated, well how periodic-like patterns in colouration can be included an integrated method of fine-scale species delimitation. By combining several methods, including BPP analysis and study molecular, morphological, ecological data from large number specimens within broad geographic range northern Europe to Mediterranean, five are recognised , reviewed here for first time. Two new southwestern coast Sweden...