Data of bottom trawl surveys conducted in the shelf zone of Kronotsky and Avachinsky Bays and off the southeastern coast of the Kamchatka Peninsula at depths of 65–210 m in 2018 and 2022, before and after the harmful microalgal bloom that occurred off the Kamchatka coast in the fall of 2020, were compared. The results indicate a significant decrease in the species diversity, population density, and biomass of benthic organisms in the lower sublittoral zone in 2022 compared to 2018. The least affected area was the northernmost region (Kronotsky Bay), while the most severely affected area was the southernmost region off the southeastern Kamchatka coast south of Cape Povorotny, where the biomass and species diversity dramatically decreased. This is consistent with the satellite monitoring data on chlorophyll a concentration off the Kamchatka coast in September 2020. According to these data, the area of the highest chlorophyll a concentration was the greatest in Avachinsky Bay and off the southeastern Kamchatka coast, where the strongest reduction in biodiversity of marine invertebrates was recorded.

The paper presents a review of the fauna of sea anemones collected and/or documented photographically in the western part of the Bering Sea: in the areas of the Vulcanologov Massif, Karaginsky and Olyutorsky Gulfs and Koryak slope.In total, about 80 species have been identified and an annotated list of sea anemones of the orders Actiniaria, Corallimorpharia, and Zoantharia is provided.This is the first comprehensive report of the species diversity of sea anemones living in the western Bering Sea, based on the recent collections and underwater imaging.

The results of monitoring of the benthic communities’ state during two years after the ecological catastrophe caused by an outbreak of planktonic microalgae off the coast of Kamchatka in autumn 2020 were presented. The consequences of this phenomenon led to the mass extinction of bottom organisms. As a result, in the zone of the upper sublittoral, a strong depletion of the benthic fauna occurred, not only many species, but also entire groups of animals fell out of its composition: most of the sponges and about a half of species of sea anemones, mollusks, echinoderms, ascidians have disappeared. However, the quantity of some groups of Crustacea has increased significantly.

Two species of sea anemones of the genus Sagartiogeton are reported from the reducing environments of the Bering Sea (NW Pacific). One species, Sagartiogeton californicus, is abundant on the Koryak slope in the methane seep sites as well as in the background, and it is also found in hydrothermal vents on the submarine Piip Volcano; another species, Sagartiogeton rufus sp. nov., forms crowded settlements in hydrothermal vent areas on the Northern summit of the submarine Piip Volcano. Taxonomy of Sagartiogeton and related genera is discussed. Genus Antipodactis is synonymized with Sagartiogeton and the family Antipodactidae with Sagartiidae. Genus Artemidactis is suggested to be a senior synonym of Sagartiogeton but formally they are not synonymized. Results of stable isotope analysis showed the absence of site-specific differences between Sagartiogeton californicus from background and methane seep communities and non-chemosynthetic origin of food sources for both Sagartiogeton-species. Zoobank Article LSID: urn:lsid:zoobank.org:pub:3F3C631A-1CAB-4F89-9947-03776AA56096.

A calcareous sponge Leucotreton kurilense gen. et sp. nov. (Sycanthidae) is described from the area of the Kuril Islands. It differs from all members of the family Sycanthidae in its aquiferous system, which is intermediate between leuconoid and sylleibid. Taxonomic status and nomenclature of several taxa formerly assigned to Sycanthidae is discussed. It is shown that the genus Dermatreton Jenkin, 1908 does not belong to Sycanthidae but this name is a senior synonym of Breitfussia Borojevic et al., 2000 (Jenkinidae), syn. nov.; Dermatreton contains three species previously included in Breitfussia: D. chartaceum Jenkin, 1908, D. schulzei (Breitfuss, 1896), comb. nov. and D. vitiosum (Brøndsted, 1931), comb. nov. It is shown that Tenthrenodes Jenkin, 1908 should be considered as a junior synonym of Sycon Risso, 1827, syn. nov. A new genus Scytotreton gen. nov. (Sycanthidae) is created to accommodate two species originally described in the genera Dermatreton and Tenthrenodes, respectively: Scytotreton hodgsoni (Jenkin, 1908), comb. nov. and S. scotti (Jenkin, 1908), comb. nov.

A taxonomy of aplousobranch ascidians from the NW Pacific coasts of Russia, including Bering Sea, Sea of Okhotsk and northern part of the Sea of Japan, is presented.Order Aplousobranchia currently comprises 14 families, 7 of which are represented in the region by at least several species.Sixty-nine species and 19 genera are recognized as valid.Three new genera and four new species are described: Bathyplacentela gen.n., Kussakinia gen.n., Protosynoicum gen.n., Bathyplacentela pedunculata sp.n., Holozoa okhotensis sp.n., H. shimushirensis sp.n., H. urupensis sp.n.A new name Neodiction nom.n. is suggested for Neodictyon Sanamyan, 1998 and Eudistoma okai nom.n. for Eudistoma parvum (Oka, 1927).All known species from this region are included and most of them redescribed based on newly collected specimens and/or on museum material.Many type species are reexamined and illustrated.Identification keys and quality photographic images are provided to simplify a task of species identification for a wide range of biologists.Special attention is paid on nomenclature of discussed families, genera and species, a subject that received little attention from most ascidian experts previously.Several serious long-standing nomenclatural problems were revealed, especially the problems associated with so called "nomina conservanda", a category uncritically and incorrectly applied to several most widely used generic names in Ascidiacea.Possible solutions of these problems are suggested.

: Burrowing sea anemone Paraedwardsia malakhovi sp.n. is described from shallow-waters of East Kamchatka and middle group of Kuril Islands. This is a first record of a member of the genus Paraedwardsia from Far East Seas of Russia. A new replacement name Edwardsiellinae nom.n. is established for subfamily Milneedwardsiinae Carlgren, 1892.How to cite this article: Sanamyan N.P., Sanamyan K.E. 2021. Paraedwardsia malakhovi , a new burrowing sea anemone (Actiniaria: Edwardsiidae) from Kamchatka and Kuril Islands // Invert.Zool. 10.15298/invertzool.18.3.07

A large solitary ascidian Microcosmus armatus sp. nov., described from the Sea of Okhotsk, represents the first record of the genus Microcosmus Heller, 1877 in the cold waters of the Northwestern Pacific. The genus belongs to the family Bolteniidae formerly known as Pyuridae.

Several species of deep-water sea anemones belonging to three genera, Sicyonis, Ophiodiscus and Tealidium, previously assigned to Actinostolidae, are recorded in North Pacific and North Atlantic and described.It is shown that these genera cannot be maintained within Actinostolidae.Family Sicyonidae was reinstated for Sicyonis and Ophiodiscus, while Tealidium, together with related Anthosactis and Hormosoma, is transferred to a new family Anthosactinidae fam.n.Recently described Tetracoelactis, originally assigned to Exocoelactinidae, is transferred to a new family Tetracoelactinidae fam.n., which shows some affinity with Sicyonidae.Removing Sicyonis from Actinostolidae in the present work resulted in the validation of this family: till now wide usage of this family name was invalid because Actinostolidae Carlgren, 1893 was a junior subjective synonym of Sicyonidae Hertwig, 1882.The following new taxa are described: Sicyonis denisovi sp.

Literature records of large actiniid sea anemones along the Atlantic coast of Canada currently include three Urticina species: U. felina, U. fecunda and U. crassicornis. The findings of the present morphological and molecular study conducted in eastern Newfoundland suggest that U. felina is often misidentified, and that this region may only harbor two similar-looking species: U. crassicornis and Cribrinopsis similis. The latter were identified using genetic analysis and comparison of key characters with the same species collected from other regions of the North Atlantic (Barents Sea), whereas no specimen corresponding to U. felina was found. Mitochondrial gene sequences of U. crassicornis, U. felina and C. similis were identical except for a different haplotype found in several specimens of U. crassicornis (with one nucleotide substitution), in contrast to five nucleotide insertions in 16S rRNA fragments of U. fecunda. Phylogenetic analysis based on three mitochondrial and two nuclear gene fragments revealed that the most closely related species among the above-mentioned were U. crassicornis and U. felina, nevertheless U. fecunda groups in the same clade as the Urticina species.

Tetracoelactis ioran gen. et sp. nov. is described from abyssal depths of the NW Pacific and assigned to the family Exocoelactinidae. The genus is unique in having of only four meristematic zones, the lowest number among all species of Actiniaria.

Sea anemones of the genus Cribrinopsis Carlgren, 1921 from the NE Pacific are revised. Specimens traditionally identified from this region as Cribrinopsis fernaldi Siebert & Spaulding, 1976, actually represent two distinct species with different morphology and habitat. One species has long tentacles, a ring of distinct rounded marginal projections, a white column and usually inhabits muddy bottom. The other has short tentacles, no special marginal projections, a bright coloration (usually variations of red and occasionally white), and inhabits rocky substrates. Additionally, the distinction of two sympatric species is supported by molecular analysis. The holotype of C. fernaldi was re-examined, which revealed that in its original description several key features of this species were incorrectly described. The holotype is conspecific with the first (white) species, which therefore should retain the name C. fernaldi. The other species is described as Cribrinopsis rubens sp. nov. Study of the holotype of another Cribrinopsis species previously reported from the NE Pacific, Cribrinopsis williamsi Carlgren, 1940, showed that this species does not resemble any known actiniid species from the NE Pacific. It probably does not belong to Cribrinopsis and its taxonomic position needs further investigation.

Ultra-abyssal Paraedwardsia hadalis sp.n. is a first species of sea anemones described from Aleutian Trench.It resembles two deep water species P. abyssorum and P. lemchei which differ from other Paraedwardsia species by weak development of tenaculi.Paraedwardsia hadalis sp.n.from 7250 m is a most deep water species of the family Edwardsiidae.

Государственный научно-исследовательский институт озерного и речного рыбного хозяйства им

Two small sea anemones, Octineon suecicum and Edwardsiella loveni, known previously only from scarce records in European waters, are reported from British Columbia, Canada.Both genera, Octineon and Edwardsiella were not previously reported from the North Pacific.It is speculated that both species have a wider distribution than it appears from scarce existing records, but due to specific habitat and being flat and firmly attached to bedrock (Octineon) or inhabiting deep narrow crevices in bedrock (Edwardsiella) they escape traditional collecting devices such as trawls or dredges.The phylogenetic and statistical analyses showed that the family Octineonidae is probably related with Hormathiidae.