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During the KuramBio expedition in 2012, macrobenthos samples were collected with an epibenthic sledge from 12 sites on the abyssal plain of the Northwest Pacific Basin adjacent to the Kuril-Kamchatka Trench (KKT) and on the western slope of the KKT, at depths between 4830 and 5780 m. In terms of the peracarid fauna, the NW Pacific abyss was found to be one of the richest and densely populated deep-sea regions of the World Ocean. With 482 species, 168 genera, 61 families and 5 orders, the superorder Peracarida was found to be the most diverse and one of the most abundant macrobenthic taxa in the collection. Of the taxa found, 3 genera and 386 (80%) species were apparently new to science, 30 genera and the family Dendrotionidae (Isopoda) being recorded for the first time in the NW Pacific. The peracarid fauna composition at the abyssal depths of the KKT region was typical of the open, non-isolated abyssal plain. The Isopoda proved the most diverse and abundant peracarid order (245 species, 61.3% of the individuals), followed by the Amphipoda (79 species, 19.6%), Tanaidacea (77 species, 9.1%), the Cumacea (70 species, 9.7%), and the Mysida (11 species, 0.23%). The highest peracarid abundance (up to 1047 ind./1000 m2) was recorded on the western slope of the trench, abundances at the abyssal plain being lower (125–639 ind./1000 m2). The peracarid distribution in the area studied was affected by a complex of various factors, the food availability reflected in the Particular Organic Matter (POM) flux belonging to the most important ones. Specifically, increases in the peracarid abundance and species richness corresponded in most cases with a high sediment organic carbon content or the high surface productivity level in the area. As indicated by the sediment composition, the food input to the deep-sea system apparently differed between the sites sampled. On the trench slope, accumulation of organic debris, transported down the slope from shallower regions, played an apparently major role. The abyss in the northern and in the southern parts of the area sampled is influenced by the high surface productivity, resulting from the regional hydrography. The area east of the Middle Kuril Islands is likely influenced by the organic material transported from the Sea of Okhotsk through the Kuril Straits.

In the samples of the expedition SokhoBio (Sea of Okhotsk Biodiversity Studies) arcturoid isopods were present at eight sites in the Kuril Basin of the Sea of Okhotsk (1685–3366 m), the Bussol Strait (2327–2358 m), and the western abyssal slope of the Kuril-Kamchatka Trench (KKT) (3371–3377 m). They were represented by eight species of three genera and two families, Antarcturus, Chaetarcturus (Antarcturidae), and Neastacilla (Arcturidae). Six species turned out to be new to science. The composition of fauna and distribution of arcturoids in the Kuril Basin and the adjacent regions are discussed. A list of all arcturoid species known from the Sea of Okhotsk and the adjacent waters off the Pacific coast of the Kuril Islands and the Southeastern Kamchatka at depths > 500 m is provided. In the abyss of the Sea of Okhotsk two species (Chaetarcturus cf. beddardi (Gurjanova, 1935) and Neastacilla birsteini sp. nov.) were found. Neastacilla birsteini sp. nov., the dominant species in the abyss of the Kuril Basin, is described herewith. The new species differs from all other species of the genus by the 6-articled antennae I. N. birsteini sp. nov. most closely resembles N. anophthalma (Birstein, 1963) comb. nov. nov. Both species can be distinguished from all other species of the genus by the absence of eyes and a long article 5 of antenna I which is longer than articles 1–3 together. N. birsteini sp. nov. differs from N. anophthalma in the following characters: the pleon of the new species is 1.5 times longer than pereonite 4 and has an elongated distal part with a notch at the apex; the pereopod I carpus is 3.2 times as long as wide.

The deep-sea Munnopsidae Lilljeborg, 1864 of the Kuril Basin of the Sea of Okhotsk, the Bussol Strait, as well as the western abyssal slope of the Kuril-Kamchatka Trench (KKT) off the Bussol Strait were studied. The material was collected during the expedition SokhoBio (Sea of Okhotsk Biodiversity Studies) in the summer of 2015. The first data on the composition and distribution of the family Munnopsidae from the SokhoBio samples are presented. In total 2190 individuals of Munnopsidae from 53 species, 26 genera and seven subfamilies have been collected at 19 of 21 C-EBS stations at all 11 sites of the SokhoBio expedition. The most abundant subfamily in the samples was Ilyarachninae Hansen, 1916 (36%), followed by Eurycopinae Hansen, 1916 (29%). In the Kuril Basin 39 species of 20 genera and 5 subfamilies were found, the main portion of munnopsids here was represented by the Ilyarachninae (39%), followed by the group of genera incertae sedis (31%) and Eurycopinae (27%). The abyssal munnopsid fauna of the Kuril Basin is an intermediate in terms of diversity and species richness between the adjacent studied abyssal areas, the Sea of Japan and the open abyssal of the KKT. Half of the collected species, 27 species (51%) are shared with the KKT area, 22 species (41.5%) are common to the Kuril Basin and the Pacific sites. About 80% of the collected species are new to science. One of the new species, Gurjanopsis kurilensis sp. nov. is described herein. Gurjanopsis Malyutina and Brandt, 2007 is the only genus within the Munnopsidae having a posteromedial notch in the pleotelson containing tiny uropods and the anus. A similar notch in the pleotelson containing uropods within Janiroideа Kussakin, 1967 is known only in species of Jaera Leach, 1814 (Janiridae G.O. Sars, 1897). The male pleopods of Gurjanopsis which cover the pleopodal cavity of the pleotelson are unusual for the family. This “operculum” is formed by the small pleopods 1 and 2 and the enlarged exopods of pleopods 3. This is similar to the pleopodal structure found in the primitive asellote superfamilies Aselloidea Latreille, 1802 and Stenotrioidea Hansen 1905, while in Janiroideа only pleopods 1 and 2 are operculate. The new species is the third species of the rare genus Gurjanopsis and the first record of the genus, previously only known from the deep-sea of the Arctic and the Antarctic, for the Pacific Ocean. The finding a species of Baeonectes Wilson, 1982 in abyssal depths of the Kuril Basin is the deepest record of the genus.

Macrofauna (46,343 invertebrates from 41 taxa) were collected by means of a camera-epibenthic sledge (C-EBS) during the expedition SokhoBio (Sea of Okhotsk Biodiversity Studies) on board of the RV Akademik M.A. Lavrentyev in 2015. In total 11 sites and 22 stations were sampled at bathyal and abyssal depths ranging from 1696 m to 4798 m in the Kuril Basin of the Sea of Okhotsk (16 stations), the Bussol Strait (two stations) and western slope of the Kuril-Kamchatka Trench (KKT) (four stations). Polychaetes occurred most frequently in the samples with 17,546 individuals, followed by Peracarida with 14,099 individuals (5625 isopods, 3887 amphipods, 3225 tanaids, 1269 cumaceans, and 90 mysids), Copepoda (4679 ind.) and Bivalvia (3999 ind.). Numbers of individuals ranged between 140 at station 3–10–6383 at station 7–3. The numbers of taxa per station were smallest at station 3–10 (4 taxa) and highest at station 2–7 (31 taxa). Peracarida were the most common malacostracan crustaceans recorded, with Isopoda comprising 40% of all peracarids within this fraction, followed by Amphipoda with 27%, Tanaidacea with 23%, Cumacea with 9% and Mysida with 1%. At station 3–10, not a single peracarid was sampled. Isopoda dominated most of the stations, especially in the abyssal sites of the Kuril Basin. Amphipoda occurred in higher numbers in the Bussol Strait at site 8 as well as at Pacific station 9-7. In the SokhoBio area, studied macrofauna was distributed very patchily. In terms of diversity and composition the abyssal macrofauna of the Kuril Basin shows an intermediate state between the adjacent studied abyssal areas: the semi-isolated Sea of Japan and the open abyssal plain of the Kuril-Kamchatka Trench (KKT) area.

Eurycope producta Sars, 1868 and Eurycope inermis Hansen, 1916 are two widely distributed and highly abundant isopod species complexes within Icelandic waters, a region known for its highly variable environment. The two species complexes have bathymetric depth ranges from 103 to 2029 m (E. producta) and from 302 to 2113 m (E. inermis). Molecular evidence was used for species delimitation within these species complexes by analyzing nuclear (18S rDNA, H3) and mitochondrial (16S rDNA, COI) sequence data. Tree-based methods (BI and ML) and four species delimitation methods (ABGD, GMYC, NDT, PTP) were applied, in order to disentangle the two species complexes. A total of eight and four species clades could be identified within samples of the E. producta and E. inermis complexes and respectively included the closely related species E. dahli Svavarsson, 1987; E. hanseni Ohlin, 1901; and E. cornuta Sars, 1864. The morphological findings coincide with the observed molecular species clades. The elucidated species clades were geographically and bathymetrically much more restricted than previously assumed. Eight species clades featured depth spans of less than 400 m and only four species clades featured depth spans of 1000 to 1500 m. Only two species clades (E. producta sensu stricto and E. inermis sensu stricto) were found on both sides of the Greenland-Scotland Ridge. Further, species distribution maps were generated using random forest, to predict potential distributional patterns for the resolved species clades of the two species complexes. We present the first attempt of combining morphological, molecular, and species distribution models in marine isopods thus far.

Since the 1990s, the marine benthos of the Greenland–Iceland–Faeroe (GIF) Ridge has been sampled through the BIOICE (Benthic Invertebrates of Icelandic waters) and subsequent IceAGE (Icelandic Marine Animals: Genetics and Ecology) projects. Isopod crustaceans formed one of the prominent macrofaunal groups. Most isopod families occurred on both sides of the ridge, but showed side-specific abundance patterns reflecting known distribution from the literature. Our results from 35,536 isopod specimens from 55 epibenthic sled stations show a depth pattern at the family level indicating typical shallow water families like, for example, Paramunnidae or typical deep-water families like, for example, Haploniscidae and Ischnomesidae, while other families did not show a clear depth trend. We hypothesize that the ridge influences the distribution of the families through its effects on the hydrography and sediment characteristics. Total organic carbon (TOC) and mud content significantly explained isopod family distributions, possibly reflecting different habitat use and lifestyle (e.g., infaunal, epifaunal). Our analysis of a subset of 27 selected BIOICE and IceAGE stations and 100 isopod species (22,574 specimens), mostly covering the upper 1000 m depths between Iceland and Norway along the Iceland–Faeroe Ridge (IFR), resulted in four main species assemblages differing in species diversity. Whereas north of the IFR, we found 76 species; south of the IFR, we found 52 species; 40 species occurred both north and south of the IFR. Although the subset of selected stations is limited to a comparably small portion of the IceAGE sampling grid and to a comparably restricted depth range of the upper 1000 m, our result shows the slope area of Northeast Iceland and around the Faeroes and the Norwegian Channel with the highest number of species, especially stations in the thermocline between 400 and 800 m depth, where we observed the turnover from shallow to deep-water faunal elements.

Coxicerberus fukudai (Ito, 1974) (Isopoda) is redescribed from Korean and Japanese localities. Molecular analysis based on two mitochondrial markers (mtCOI and Cytb) of the studied populations shows two diverged lineages, reflected in high (10.5% and 9.5%) pairwise differences and high haplotype diversity. One of the clades is shared by Korean and Japanese populations with little divergence rate (0.02% and 0.03%), and another is only found in Korea. We failed to find any consistent morphological differences across the examined populations, probably indicating the existence of cryptic species. We also examined the possible influence of the endosymbiotic bacterium Wolbachia on the haplotype diversity. Infection with the bacterium shows a distinct distribution pattern, with all the southern Korea populations being infected, whereas the northern populations are not.

The present paper provides data of the world-wide distribution, abundance and diversity of the rare deep-sea munnopsid genus, Acanthocope Beddard, 1885 and presents an identification key to the 18 known species of Acanthocope. Two new species, Acanthocope puertoricana sp. nov. from the tropical abyssal area near the Puerto Rico Trench and Acanthocope galaica sp. nov. from the Galicia Bank, Northeastern Atlantic are described. Additionally, Acanthocope annulatus Menzies, 1962 and Acanthocope eleganta Malyutina and Brandt, 2004 have been collected in the Puerto Rico Trench area, whereas Acanthocope galatheae Wolff, 1962 were collected along a latitudinal transect crossing the tropical abyssal North Atlantic during the Vema-TRANSIT expedition. A. puertoricana is most similar to A. carinata Chardy, 1972 from the Northwestern Atlantic and differs from the latter by: a more slender body; a broader head; a more slender and shorter lateral projections of the pleotelson; the presence of ventral spines on natasome; and a longer uropod. A. galaica sp. nov. is most similar to A. spinicauda Beddard, 1885 and differs from the latter by having a more elongate pleotelson with almost straight lateral margins between lateral spines, whereas the margins are more convex in A. spinicauda. Pereopods 5 and 6 of A. galaica have broader carpi than in A. spinicauda.

We analyzed composition and variations in benthic macrofaunal communities along a transect of the entire length of the Vema-Fracture Zone on board of RV Sonne (SO-237) between December 2014 and January 2015 in order to test whether the Mid-Atlantic Ridge serves as a barrier limiting benthic taxon distribution in the abyssal basins on both sides of the ridge or whether the fracture zone permits the migration of species between the western and eastern abyssal Atlantic basins. The Puerto Rico Trench, much deeper than the surrounding abyssal West Atlantic, was sampled to determine whether the biodiversity of its hadal macrofauna differs from that of the abyssal Atlantic. The composition of the macrofauna from the epibenthic sledge catches yielded a total of 21,332 invertebrates. Crustacea occurred most frequently (59%) with 12,538 individuals followed by Annelida (mostly Polychaeta) (26%) with 5491 individuals, Mollusca (7%) with 1458 individuals, Echinodermata (4%) with 778 individuals, Nematoda (2%) with 502 individuals and Chaetognatha (1%) with 152 and Porifera (1%) with 131 individuals. All other taxa occurred with overall less than ten individuals (Hemichordata, Phoronida, Priapulida, Brachiopoda, invertebrate Chordata, Echiurida, Foraminifera (here refereed to macrofaunal Komokiacea only), Chelicerata, Platyhelminthes). Within the Crustacea, Peracarida (62.6%) with 7848 individuals and Copepoda (36.1%) with 44,526 individuals were the most abundant taxa. Along the abyssal Vema-Fracture Zone macrofaunal abundances (ind./1000 m 2 ) were generally higher on the eastern side, while the highest normalized abundance value was reported in the Puerto Rico Trench at abyssal station 14-1 2313 individuals/1000 m 2 . The lowest abundance was reported at station 11-4 with 120 ind./1000 m 2 located at the western side of the Vema-Fracture Zone. The number of major macrofaunal taxa (phylum, class) ranged between five (stations 12-5, 13-4 and 13-5 at hadal depths in the Puerto Rico Trench) and 14 (station 9-8) in the western abyssal basin of the Vema-Fracture Zone. Differences are seen in the distribution of Porifera at macrofaunal level between eastern and western sides of the Vema-Fracture Zone. Macrofaunal composition of the study area is compared with data from other expeditions in the Atlantic and the northwest Pacific Ocean.

Two new abyssal species of Dendrotionidae are described: Dendromunna kurilensis sp. nov. from the Northwest Pacific Basin to the east of the Kuril–Kamchatka Trench and D. okhotensis sp. nov. from the Kuril Basin of the Sea of Okhotsk. The new species represent the first records of the family for the Northwest Pacific and the first records of the genus for the North Pacific. The new species differ from the remaining species of Dendromunna by the extremely long antennae and pereopods (antenna I is about 0.7–0.8 body length, article 4 of antenna II is about 0.6–0.7 body length, bases of pereopods are about 0.2–0.3 body length), the male pereopod I with concave lateral margins, short pereonite 1 (

The asellote family Gnathostenetroididae Kussakin, 1967 is reported for the first time from Australian waters. Four new species of Gnathostenetroides Amar, 1957 from the Great Barrier Reef are described. The genus Maresiella Fresi and Scipione, 1980 is here placed into synonymy with Gnathostenetroides and a new diagnosis is given for Gnathostenetroides together with a key to the 12 species and a map of the distribution of the genus. The genus Dignatroides Stock and Vonk, 1990 is placed into synonymy with Caecostenetroides Fresi and Schiecke, 1968, and a new composition of the family Gnathostenetroididae, the updated diagnosis and a key to the three genera are provided.

As part of the New Zealand government Ocean Survey 20/20 programme (OS 20/20, 2006–2013), samples from the Chatham Rise and Challenger Plateau collected in 2007 were analysed to determine the effects of key environmental parameters, in particular sediment and water mass properties, on spatial changes in the community structure (abundance, diversity and community composition) of bathyal asellotan isopods. Benthic collections were obtained in austral autumn (May/June 2007) and included a total of 21 epibenthic sledge samples taken from the upper slope between 218 and 1239 m. Due to the contrasting environmental settings between the Chatham Rise and Challenger Plateau, in terms of surface productivity and habitat heterogeneity, we expected the abundance, regional (or gamma-) diversity and community composition of benthic isopods to significantly differ between the two regions, and furthermore local (or alpha-) diversity and abundance (density) to decrease with increasing depth. Consistent with our assumptions, multivariate PERMANOVA analysis revealed a clear distinction in species composition between the Chatham Rise and Challenger Plateau with satellite surface chlorophyll (Chl) a and bottom temperature being the main environmental drivers. In contrast to previous benthic studies from the same sampling campaign, however, differences in isopod density and diversity between the two regions were not significant, either at species, or generic and family level. In addition, no depth-related changes in abundance and diversity could be observed at any hierarchical level. Instead, isopod densities at species and generic level were positively correlated with satellite surface Chl a and %silt, whilst species and generic diversity could be positively linked to the amount of total organic matter (TOM) in surficial sediments. In total, 97 asellote species in 54 genera and 15 families could be identified from both regions, of which 90.7% were likely new species. Species diversity was average to high when compared to other regions in the Northern and Southern hemispheres. However, neither for Chatham Rise nor for the Challenger Plateau did the species accumulation curves reach an asymptote, indicating that additional samples are required to provide more robust diversity estimates.

The benthos of the Kuril–Kamchatka Trench (KKT) was sampled during the KuramBio II expedition on board the RV Sonne in 2016. Macrobenthos was, for the first time, collected in the KKT hadal zone using an epibenthic sledge. Isopod crustaceans were one of the dominant taxa, and Munnopsidae was the most abundant and diverse asellotan family, comprising 49% of all Isopoda. During the expedition, a total of 67 species of 24 genera from eight subfamilies of Munnopsidae were collected, including 41 species of 15 genera from 18 hadal stations. In general, the taxonomic diversity of the munnopsid fauna in the KKT hadal zone was lower than that of the Northwest Pacific (NWP) abyssal fauna adjacent to the KKT. Two subfamilies, Lipomerinae and Acanthocopinae, were not found in the hadal zone. Most of all collected munnopsid individuals (92%) belonged to the three subfamilies: Eurycopinae (42%; 15 species), Betamorphinae (33%; four species), and Storthyngurinae (17%; two species). The rest of all munnopsid individuals (8%) belonged to the subfamilies Ilyarachninae, Munnopsinae, Syneurycopinae, and to a group of incertae sedis genera. The eight most numerous species representing the three most widely distributed and speciose genera—Eurycope, Betamorpha and Rectisura—encompassed 78% of all munnopsid individuals. The study of the Munnopsidae collected during the four expeditions (SoJaBio in 2010, KuramBio in 2012, SokhoBio in 2015 and KuramBio II in 2016) extended the known diversity of the munnopsid species in the KKT area from 39 described species of 14 genera to 157 species of 36 genera. Most collected species (87%) were new to science. The fauna richness showed a tendency to decrease from the open abyssal towards the hadal zone of the KKT and towards the semi-isolated abyssal Kuril Basin of the Sea of Okhotsk, and especially towards the more isolated abyss of the Sea of Japan. A comparison of the munnopsids from NWP and those from other oceans showed their similar composition with the same dominant subfamilies. The main difference between the abyssal munnopsids from the NWP and from the Atlantic sector of the Southern Ocean was the proportion of the Lipomerinae (2% vs. 16% of munnopsid individuals, respectively). A trend of reduction in the munnopsid diversity from abyssal to hadal depths, similar to that in the KKT, was also revealed in the Puerto-Rico Trench.

In the past seven years, the biology of the bathyal, abyssal and hadal faunas of meio- macro-, and megabenthos of the northwestern (NW) Pacific have been intensively investigated by Russian and German partners. A total of four joint expeditions with both RV Akademik M.A. Lavrentyev as well as RV Sonne have provided data on the systematic, evolution and biogeography of the deep-sea fauna of the Sea of Japan, Sea of Okhotsk, the Kuril-Kamchatka Trench (KKT) and the NW Pacific open abyssal plain. Goals of these expeditions were to study the biodiversity, biogeography and trophic characteristics of the benthic organisms in different NW Pacific deep-sea environments, to compare more isolated deep-sea basins with more easily accessible ones and to test whether the hadal of the KKT isolates the fauna of the Sea of Okhotsk to the fauna of the open NW Pacific area. An outline of some important results in presented. These data build the basis of the Beneficial ( B iog e ography of the n orthwest Pacific fauna. A benchmark study for e stimations o f alien i nvasions into the Ar c tic Ocean i n times of r a pid c l imate chance) project which aims to deliver a sound biogeographic baseline study of the NW Pacific area. These data will serve as a solid basis and benchmark for predicting potential species invasions supported by the retreat of Arctic Ocean sea ice. Thus our data will be beneficial for the assessment of state and quality of the Arctic marine ecosystem in a changing environment.

Abyssal macrofaunal composition of 21 epibenthic sledge hauls from twelve stations taken in the Kuril–Kamchatka Trench (KKT) and at the adjacent abyssal plain, Northwest Pacific, is presented. Sampling with the fine meshed epibenthic sledge yielded higher abundances and species richness than was reported from previous expeditions from board of RV Vityaz. In total 84,651 invertebrates were sampled with RV Sonne between July and September of 2012 (31,854 invertebrates if standardised for 1000 m2 trawled distances) from 41 taxa of different taxonomic ranks (15 phyla, 28 classes, 7 orders) were sampled from a trawled area of 53,708 m² and have been analyzed. Few taxa were frequent and most taxa were rare in the samples, twelve taxa occurred with more than 1% frequency. Of these, the Polychaeta were most abundant followed by the benthic Copepoda and Isopoda. Total numbers of individuals varied between stations and were highest with 4238 individuals at station 2-10 close to the KKT in 4865 m depth and lowest with 374 individuals at station 6-11 in 5305 m depth. At this station also the lowest number of taxa occurred (18 taxa) while the highest number occurred with 31 taxa at station 3-9 in 4991 m depth. Numbers of individuals decreased with increasing depth between 4830 and 5780 m. Crustaceans of the superorder Peracarida were one of the dominating taxa with four orders occurring frequently in most samples. In total, Isopoda were most important and occurred with 59% of all peracarid orders sampled, followed by Amphipoda with 21%, Tanaidacea with 11%, Cumacea with 9%, and Mysidacea with

The isopod family Munnopsidae Lilljeborg, 1864 was the most diverse and species richest family among all macrobenthic organisms collected during the expedition KuramBio in the abyssal area off the Kuril–Kamchatka Trench (R.V. Sonne, 2012). The munnopsid genus Microcope Malyutina, 2008 , represented by two species, was one of the most abundant and frequent isopod genera sampled at all stations. Microcope ovata ( Birstein, 1970 ), the only known Pacific species of Microcope to date, is redescribed based on the new collections, since the types of the species were lost. Descriptions of a new species from the KuramBio samples, Microcope stenopigus sp. nov. and a new species from the opposite side of Pacific Ocean, from the southeastern Australian slope, Microcope justi sp. nov., are presented herein. These findings increase the number of described species of Microcope to five and extended the geography of the genus from the previously known South Atlantic, Antarctic and the northwestern Pacific to the new localities from the southwestern Pacific. The depth range for the genus was also extended from 2014–7370 m, to 427–7370 m. A map of the distribution of the genus Microcope and a key to the described species of Microcope are provided.

This study focusses on the isopod biodiversity in the abyssal area southeast of the Kuril–Kamchatka Trench. The KuramBio (Kuril–Kamchatka Biodiversity Studies) expedition in summer 2012 collected altogether 10,169 isopods from 21 C-EBS hauls at 12 stations, belonging to 19 families, 73 genera and 207 species from the depth range between 4830 and 5780 m. Munnopsidae and Desmosomatidae were the most abundant and species-rich families, Eurycope (Munnopsidae) and Macrostylis (Macrostylidae) the most abundant genera. An nMDS plot on the basis of the Cosine similarity index reveals no clear pattern and all hauls to be different from each other. We compared our data with 12 stations from the same depth range sampled by the Russian RV Vityaz about 50 years ago and were able to identify several species collected by the RV Vityaz . The identified isopod species belonged to the families Munnopsidae, Macrostylidae, Haploniscidae, Desmosomatidae, Ischnomesidae and Nannoniscidae. Of the 333 individuals collected by the RV Vityaz , Haploniscidae and Munnopsidae were the most abundant families. Desmosomatidae were only represented by Vityaz samples are not approaching an asymptote, indicating that even after repeated sampling just a part of the local fauna has been recorded so far.

Individual wood fragments obtained from Agassiz trawl samples in the abyssal plain area off the Kuril–Kamchatka Trench were analysed for faunistic components. Out of seven pieces of wood collected, only five harboured fauna and each showed distinctively different colonization patterns. In total, 257 specimens, mainly belonging to the phyla Arthropoda, Nematoda, Mollusca and Annelida, were collected from the available pieces of wood. While wood-boring bivalves of the genus Xylophaga, generally seen as opportunists among wood-converting organisms, were present at nearly all stations, the overwhelming majority of taxa found were restricted to individual pieces of wood. A fresh piece of wood from a site opposite to the Tsugaru Strait, was the most heavily colonized. The presence of shallow or even putative fresh-water taxa beside truly deep-water components possibly suggests a recent sinking of that particular wood fragment and demonstrates the role of such ephemeral organic objects in deep-sea ecosystems as energy-rich feeding grounds and potential distributional stepping stones. Detailed studies of driftwood communities on single sunken wood fragments from deep oceans are limited. The present data not only demonstrate a tolerance of some taxa to changes in physical parameters, such as hydrostatic pressure, salinity and temperature, but also indicate a higher biodiversity on fresher wood pieces compared to wood which already underwent decomposition processes. It is, however, not clear whether the species diversity was linked to the type of wood, since exhaustive analyses on the wood pieces themselves were not conducted.

Angelika Brandt, Marina V.Malyutina (2015): The German-Russian deep-sea expedition KuramBio (Kurile Kamchatka biodiversity studies) on board of the RV Sonne in 2012 following the footsteps of the legendary expeditions with RV Vityaz. Deep-Sea Research II 111: 1-9, DOI: 10.1016/j.dsr2.2014.11.001

The abyssal macrobenthos of the Kuril–Kamchatka Trench (KKT) area was sampled for the first time using a fine-meshed camera-epibenthic sledge (C-EBS) during the German–Russian KuramBio expedition 2012 (RV Sonne, 223 cruise). Crustaceans of the order Isopoda were one of the dominant macrobenthic taxa, and the family Munnopsidae was the most abundant and diverse among 17 collected asellotan families, comprising about 48% of all isopods. During the KuramBio expedition no less than 80 species of 28 genera and eight subfamilies of Munnopsidae were collected with 21 EBS hauls at 12 stations. About 80% species are new to science and half of the genera and the subfamily Lipomerinae are recorded for the first time in the Northwest Pacific. The most abundant and speciose subfamily was Eurycopinae (58% of all specimens and 29 % of species), followed by Ilyarachninae (12% and 16%). Most species are rare and occur with low abundance at one or few stations. Ten most numerous species belonging to the genera Eurycope (5 species), Microcope (2), Disconectes (1), Ilyarachna (1) and Aspidarachna (1) comprised 68% of all munnopsids. The species Eurycope sp.1 and Microcope ovata ( Birstein, 1970) were the most abundant and frequent species, occurring at all stations. The highest abundance of Munnopsidae and high diversity, with 32 species, occurred at station 3–9 on the western slope of the KKT. The cluster analysis of the Bray–Curtis similarity shows a low similarity between stations. The least similar was station 1-10, with only 26% similarity with other stations. Low similarity also characterized station 3–9 (34%). The comparison with known data revealed differences in species composition of Munnopsidae of the abyssal plain of the KKT area and the fauna of adjacent bathyal and hadal zones. Similar ratios of the munnopsid subfamilies and genera and some similar species have been revealed for the KuramBio and ANDEEP areas.

Collections of munnopsid isopods of the BIOICE (Benthic Invertebrates of Icelandic Waters; 1991–2004) and the IceAGE1 (Icelandic Marine Animals: Genetics and Ecology; since 2011) expeditions included ten species of the genusEurycopeG.O. Sars, 1864, thereof are two species new to science. Thus, the descriptions of the two new species are presented herein.Eurycope elianaesp. n. is distinguished from the other species of the genus mainly by two long, slightly robust, simple setae on the tip of the rostrum in combination with the size and shape of the rostrum itself.E elianaesp. n. shares the presence of two long, slightly robust, simple seta on the tip of the rostrum withE. tumidicarpus. The shape of the rostrum itself is more similar toE. inermisand species of theE. complanatacomplex.E. aculeatasp. n. is characterized by possessing dorsomedial acute projections on pereo-nites 5–7, which is unusual for the genus.E. aculeatasp. n. is most similar toE. cornuta. Both new species are, so far, known only from localities south of the Greenland-Scotland Ridge.

The Greenland–Scotland Ridge (GSR) is a major topographic feature, extending from Greenland to Scotland. It constrains the water exchange between the northernmost North Atlantic Ocean and the Greenland, Iceland and Norwegian Seas (GIN Seas) and thus forms a potential barrier for faunal exchange from the Arctic to the North Atlantic (and vice versa). Recently an increase in Atlantic water inflow has been observed, leading to changes in physical parameters (i.e. temperature and salinity), which may have an impact on the resident fauna. In this study, we analyzed the composition and distribution of six selected genera of the isopod family Munnopsidae (Crustacea) occurring north and south of the GSR. We examined 82 epibenthic sledge samples and 26 additional sub-samples taken in the course of the Benthic Invertebrates of Icelandic Waters (BIOICE) and Icelandic Marine Animals: Genetics and Ecology (IceAGE) projects, respectively, covering a total depth range from 103 to 2752 m depth. Overall, 58 of the evaluated stations originated in the area north of the GSR, while the remaining 50 samples were collected south of the ridge. In total, 10517 individuals could be assigned to 15 species, most belonging to the genus Eurycope Sars, 1864. Due to the presence of the GSR as well as differences in the environment, we expected significant dissimilarities in faunal composition between the two study areas. However, most species (8) occurred on both sides of the ridge, while four species were restricted to the region north of Iceland, and three to the region south of the ridge. Depth (or factors related to depth) appeared to be the most important factor in driving distributional patterns of the studied species. Temperature was also an important driver, but not to the same extent as depth. On the contrary, salinity and sediment type did not have much influence on munnopsid distribution patterns. Hence, the presence of the ridge does not restrict faunal exchange between the northern North Atlantic Ocean and GIN Seas for most of the investigated species, which may be explained by the good swimming abilities and the ecological flexibility of these munnopsid species.

Reductogonium iroquois gen. nov. sp. nov., a new genus and species of paramunnid isopods from the Northwest Pacific open abyssal plain to the east of the Kuril-Kamchatka Trench, is described based on materials from the KuramBio expedition (2012). The new genus is distinguished from other paramunnid genera by its reduced pereonite 7 that lacks appendages in adult individuals (one seta is presented instead of the pereopod VII on its position). It is also distinguished by its head, which has a medial crest bearing a tuft of setae on its posterior part, and by the extremely long articles of antennae and pereopods. The unusual paedomorphic features of the new genus might be adaptations to deep-sea conditions. Paedomorphosis was recorded for different taxa of deep-sea animals. The reduction of the last pair of pereopods, which corresponds to the state of manca stages, was observed independently in different families and orders of Isopoda. Finding a new species and a new genus of the Paramunnidae with paedomorphic features confirmed that this phenomenon is a common evolutionary strategy for deep-sea Asellota.

Areas of the Northwest (NW) Pacific have been investigated in the last century from board of the Russian RV Vityaz. During the past decade intensive collaboration between German and Russian scientists has yielded a wealth of precious material partly from unknown areas. The samples are comparable and were retrieved using comparative epibenthic sledge (EBS) deployments following a standardized sampling approach. In the present paper we investigate a large number of EBS samples (76) from a widespread geographic area. Macrofaunal high-taxonomic-level taxa composition is analysed based on four joint expeditions performed between 2010 and 2016, led by German and Russian teams in the NW Pacific, the Sea of Japan, the Sea of Okhotsk, and the Kuril-Kamchatka Trench and adjacent abyssal plain. In total, 410,279 invertebrates were sampled with an epibenthic sledge and more than half of all animals were collected in the Sea of Japan (240,803 individuals). Arthropods, represented by crustaceans, were dominant throughout all geographic areas (199,044 ind.), followed by Annelida (84,751 ind.), Echinodermata (46,317 ind.), and Mollusca (43,391 ind.). Within these phyla, eleven taxa occurred with more than 10,000 individuals in the samples from all geographic areas. The most numerous were the Peracarida (104,139 ind., represented by Isopoda [42,511 ind.], Amphipoda [29,375 ind.], Cumacea [16,364 ind.], Tanaidacea [15,889 ind.]), followed by Polychaeta (84,751 ind.), Copepoda 76,496 ind., Bivalvia (36,286 ind.), Ophiuroidea (34,818 ind.), Nematoda (24,968 ind.), Ostracoda (11,304 ind.), and Holothuroidea (10,772 ind.). The pattern of occurrence per taxon varied between geographic areas. In general, Bivalvia and Holothuroidea were more frequently recorded from hadal stations, but no significant differences could be observed between geographic areas (Sea of Japan, Sea of Okhotsk, and open NW Pacific) at high level taxa (classes, subclasses, superorders) when community composition is compared and depth differences are taken into account. However, significant differences between all depth zones (p

We report three new species of isopod crustaceans that belong to a rare higher taxon of asellote Isopoda. This taxon does not fit into current classifications. The isopods occurred in abyssal soft sediments, near manganese nodules, and in the vicinity of hydrothermal vents. Given their wide spatial occurrence across the Atlantic and Pacific Oceans, a cosmopolitan distribution is assumed. A cladistic analysis revealed a close relationship with the Macrostylidae, a common representative of the deep-sea macrofauna. Analyses of character evolution across the Janiroidea showed sufficient synapomorphies to justify the erection of Urstylis gen. nov. and the new family Urstylidae based on the three new species. All taxa are described in this paper. Urstylidae is characterized, amongst other apomorphies, by an elongate habitus with spade-like head; uropods are long, styliform; one pleonite is free; antennal merus and carpus are relatively short; the first pereopod is carpo-propodosubchelate, and more robust and shorter than pereopod II. Several characters, such as the pereopods’ posterior scale-like claw that basally encloses the distal sensilla may be interpreted as ancestral when compared to the situation in the highly derived Macrostylidae. © 2014 The Linnean Society of London

Faunistic data from a newly designed camera-epibenthic sledge (C-EBS) are presented. These were collected during the joint Russian–German expedition SoJaBio ( S ea o f Ja pan Bio diversity Studies) on board the R.V. Akademik Lavrentyev from four transects (A–D) between 460 and 3660 m depth. In total, 244,531 macro- and megafaunal individuals were sampled with the classes Malacostraca (80,851 individuals), Polychaeta (36,253 ind.) and Ophiuroidea (34,004 ind.) being most abundant. Within the Malacostraca, Peracarida (75,716 ind.) were most abundant and within these, the Isopoda were the dominant taxon (27,931 ind.), followed by Amphipoda (21,403 ind.), Cumacea (13,971 ind.) and Tanaidacea (10,830 ind.). Mysidacea (1581 ind.) were least frequent. Bivalvia, Amphipoda, Cumacea and Mysidacea as well as inbenthic meiofaunal Nematoda occurred in higher numbers at the shallower stations and their numbers decreased with increasing depth. Polychaeta, Isopoda, and Tanaidacea, on the contrary, increased in abundance with increasing depth. Only one isopod species was sampled at abyssal depths in the Sea of Japan but at very high abundance: Eurycope spinifrons Gurjanova, 1933 (Asellota: Munnopsidae). Echinoderms occurred frequently at the shallower slope stations. Ophiuroids were dominating, followed by holothurians, and echinoids and asteroids which occurred in lower numbers and primarily at the shallower stations of transects A and B. Only 2163 individual anthozoans were recorded and these were mostly confined to the lower slope. The technical design of a new C-EBS is described. Next to temperature-insulated epi- and suprabenthic samplers, it is equipped with still and video cameras, which deliver information on seabed topography and megafaunal occurrence. Furthermore, Aanderaa CTD and SEAGUARD RCM allow for collection of physical parameters, such as near bottom oxygen composition, temperature and conductivity.

During the expedition SoJaBio (Sea of Japan Biodiversity studies) a rich collection of peracarid crustaceans from the slope and the deep-sea basin of the Sea of Japan (at depth range from 450 to 3660 m) was made. The superorder Peracarida was recognized as the most abundant taxon of the macrobenthos in the investigated area and comprised 146 species, 85 genera, 42 families and five orders. From these taxa 93 species, 18 genera and 10 families are reported for the first time in the Sea of Japan below 500 m. Among them, 42 species and two genera were apparently new to science. The diversity and species richness as well as abundance of most of the peracarid species were highest at the shallowest slope stations (∼ 450–550 m) and decreased with depth. Conversely, the abundance of three species, Eurycope spinifrons Gurjanova, 1933 (Isopoda), Chauliopleona hansknechti Larsen et Shimomura, 2007 and Paratyphlotanais japonicus Kudinova-Pasternak, 1984 (Tanaidacea) increased distinctly below the slope (∼2600–3300 m). It is assumed that these species are opportunistic taxa which have recently colonized the geologically young pseudo-abyssal habitats of the Sea of Japan. On the basis of faunistic similarity between 24 stations, three distinct faunal assemblages were identified, distributed on the slope (∼450–1500 m), lower slope (∼2500–2700 m) and at the pseudo-abyssal stations. The key peracarid species for each of them were determined.

A small collection of isopods of the family Munnopsidae Lilljeborg, 1864, including four species from the slope and the deep-sea basin of the Sea of Japan (Northwest Pacific), was studied. The new species Baeonectes brandtae sp. nov. which occurs at depths of 455–1525 m is described. It is the second species of Baeonectes Wilson, 1982 described from the Sea of Japan and the deepest recorded species of the genus. Eurycope spinifrons Gurjanova, 1933 , the only Eurycope species known from the Sea of Japan is redescribed. It is the most abundant species in the studied deep-sea macrobenthic communities in all samples.

Due to isolation and a period of severe anoxic conditions in geologically recent times, biodiversity is low in the deep Sea of Japan. Among a small group of species inhabiting depths below 2500, only one isopod species, Eurycope spinifrons, was found during the SoJaBio expedition in 2010, but it was the most abundant species of all benthic taxa. E. spinifrons was found with remarkably high numbers of individuals at the sampled stations below 2500 m, providing a rare opportunity to investigate aspects of population structure and reproduction of a deep-sea isopod. The distribution, population structure, fecundity and depth dependent density of E. spinifrons were studied. Brooding females were the longest in body size and least abundant, while mancae were the shortest and most abundant. The mean length of individuals showed little deviation among the stations below 2500 m, ranging from 4.21±0.29 mm in brooding females to 1.20±0.26 mm in free-living mancae. Iteroparity is demonstrated for E. spinifrons. It is argued that females have continuous reproduction which increases in the summer. The length of the brooding females is positively correlated with the number of eggs in the marsupium in our sample (r=0.291; p

Are there widespread peracarid species in the deep sea (Crustacea: Malacostraca)?The global zoogeographic distribution of the most widespread peracarid species occurring in three or more ocean basins below 2000 m is analysed. Basing on the published data we investigated 45 peracarid species, which have a most widespread distribution and most likely are cosmopolitan. Thirty-three species have a wide distribution in the Northern Hemisphere. Most species occur in the North Atlantic, however, 16 of these species occur also in the North Pacific, a more limited number of species occurs in the South Atlantic or South Pacific The Southern Ocean displays some special zoogeographic features and 22 widespread species occur there below 2000 m, including highly eurybathic ones. In total, 11 of the analysed species occur in all oceans.Eucopia australis(Lophogastrida),Munneurycope murrayi(Isopoda) andEurythenes gryllus(Amphipoda) are the species with the widest distributions. Other peracarids occurring in all oceans are: the isopodsParamunnopsis oceanicaandEurycope sarsi, the mysidCaesaromysis hispidathe lophogastridEucopia unguiculata, the amphipodMesopleustes abyssorumand the tanaidsExspina typica, Paranarthura insignisandPseudotanais nordenskioldi. No cumacean species has been reported with an ocean-wide distribution butCampylaspis glabraoccurs in the Atlantic, Indian and Pacific oceans. Among plenty of rare species in each order there are only few species with wide distribution records. There is evidence from molecular genetic studies that some of the widespread peracarids represent several cryptic species, however, some,e.g. Eucopia australis, seem to be truly cosmopolitan species. Geography of sampling is biasing our view of biogeography. The history and quality of taxonomic work as well as the reliability of geo- graphic records (quality control of large databases) limits our investigations of widespread or cosmopolitan species as much as the limited knowledge of variation within most species causes difficulties in defining morpho-species with certainty.

Dubinectes infirmus sp. n., Munnopsidae, is described from the Argentine Basin, southwest Atlantic, at depths between 4586–4607 m. The new species is distinguished by a narrow rim of the pleotelson posterior margin which is not raising over its dorsal surface; article 3 of the antennula is subequal in length to article 2; distomedial lobes of male pleopod 1 are of same size as distolateral lobes; stylet of male pleopod 2 is subequal in length to protopod; uropod exopod is more than a half of endopod length. Some generic characters which are weakly pronounced in the new species or have different state are defined more precisely in the revised diagnosis of Dubinectes. The modified diagnosis of the genus, a key to the species of Dubinectes as well as the distribution of the genus are presented.

Three new species of the genus Belonectes Wilson & Hessler, 1981, from the munnopsid subfamily Eurycopinae Hansen are described from the deep Weddell Sea, Atlantic sector of the Southern Ocean. Belonectes grasslei sp. nov., B. stoddarti sp. nov., and B. daytoni sp. nov. are the first species of the genus described from the region: previously only two species of Belonectes were known from the northeastern Atlantic and the Peru-Chile Trench, the southeastern Pacific. The modified diagnosis of the genus Belonectes and a key to the species of the genus are presented. The pattern of the total ventral sculpture of the natasome, a medial lobe of article 4 of the maxillipedal palp which is larger than article 5 and the navicular male pleopod 1 with its deep keel are suggested to be additional important generic characters of Belonectes. The most useful characters to distinguish species of Belonectes are the size of article 1 of the antennula, the shape and size of the articles 3–5 of the maxillipedal palp, the shape of the distal margin of the male pleopod 1, the shape of distolateral part of the protopod of the male pleopod 2, the size and shape of the preanal ridge, and the size of the exopod of the uropod.

Storthyngura longispina sp. nov. and S. antarctica sp. nov. are described from the deep sea of the West-Atlantic part of Antarc­ tica. The new species are most similar to S. elegans Vanhoffen, 1914 and S. parka Malyutina & Wagele, 2001, forming a group of closely related species. New data on three known species from the region: S. elegans Vanhoffen, 1914, S. kussakini Brandt & Malyutina, 2002 and S. phyllosoma (Just, 2001) comb, nov., and redescription of S. snanoi Menzies, 1962 from the north­ western Atlantic are also presented. The genus Storthyngura is re-evaluated, and the recently described genus Platyprotus Just, 2001 is reduced to a junior synonym of Storthyngura.

Storthyngura kussakini sp. nov. was sampled in the Southern Ocean at a depth of 181–182m from on board the RV Polarstern in February of 1996. The new species differs from all other Storthyngura by the narrow posterior legs, and from the most similar Storthyngura argentica George & Menzies, 1968 from the Scotia Sea by the absence of the dorsal spines on the head, pleonite and pleotelson and the different shape of the pleotelson and pleopod 1.

A redescription of Storthyngura elegans Vanhoffen, 1914 from the Southern Ocean and the description of Storthyngura parka sp. nov. from the eastern Pacific off the coast of Peru are presented. The new species is most similar to S. elegans and can be distinguished by short dorsal spines on pereonites 2–4, short coxal lobes of pereopods 3 and 4, long anlerolateral spines of pereonite 4, a rounded caudal margin of the pleotelson, without notch, and some details of the appendages.

The family Munnopsidae was the most abundant and diverse among 22 isopod families collected by the ANDEEP deepsea expeditions in 2002 and 2005 in the Atlantic sector of the Southern Ocean. A total of 219 species from 31 genera and eight subfamilies were analysed. Only 20% species were known to science, and 11% of these were reported outside the ANDEEP area mainly from other parts of the SO or the South Atlantic deep sea. One hundred and five species (50%) were rare, occurring at only 1 or 2 stations. Seventy-two percent of all munnopsid specimens belong to the most numerous 25 species with a total abundance of more than 75 specimens; 5 of these species (40% of all specimens) belong to the main genera of the world munnopsid fauna, Eurycope, Disconectes, Betamorpha, and Ilyarachna. About half of all munnopsid specimens and 34% of all species belong to the subfamily Eurycopinae, which is followed in occurrence by the Lipomerinae (19%). Munnopsinae is the poorest represented subfamily (1.5%). The composition of the subfamilies for the munnopsid fauna of the ANDEEP area differs from that of northern faunas. Lipomerinae show a lower percentage (7%) in the North Atlantic and are absent in the Arctic and in the North Pacific. This subfamily is considered as young and having a centre of origin and diversification in the Southern Ocean. The analyses of the taxonomic diversity and the distribution of Antarctic munnopsids and the distribution of the world fauna of all genera of the family revealed that species richness and diversity of the genera are highest in the ANDEEP area. The investigated fauna is characterised also by high percentage of endemic species, the highest richness and diversity of the main munnopsid genera and subfamily Lipomerinae. This supports the hypothesis that the Atlantic sector of SO deep sea may be considered as the main contemporary centre of diversification of the Munnopsidae. It might serve as a diversity pump of species of the Munnopsidae to more northern Atlantic areas via the deep water originating in the Weddell Sea. r 2007 Elsevier Ltd. All rights reserved.

Based on our current knowledge about population genetics, phylogeography and speciation, we begin to understand that the deep sea harbours more species than suggested in the past. Deep-sea soft-sediment environment in particular hosts a diverse and highly endemic invertebrate fauna. Very little is known about evolutionary processes that generate this remarkable species richness, the genetic variability and spatial distribution of deep-sea animals. In this study, phylogeographic patterns and the genetic variability among eight populations of the abundant and widespread deep-sea isopod morphospecies Betamorpha fusiformis [Barnard, K.H., 1920. Contributions to the crustacean fauna of South Africa. 6. Further additions to the list of marine isopods. Annals of the South African Museum 17, 319–438] were examined. A fragment of the mitochondrial 16S rRNA gene of 50 specimens and the complete nuclear 18S rRNA gene of 7 specimens were sequenced. The molecular data reveal high levels of genetic variability of both genes between populations, giving evidence for distinct monophyletic groups of haplotypes with average p-distances ranging from 0.0470 to 0.1440 (d-distances: 0.0592–0.2850) of the 16S rDNA, and 18S rDNA p-distances ranging between 0.0032 and 0.0174 (d-distances: 0.0033–0.0195). Intermediate values are absent. Our results show that widely distributed benthic deep-sea organisms of a homogeneous phenotype can be differentiated into genetically highly divergent populations. Sympatry of some genotypes indicates the existence of cryptic speciation. Flocks of closely related but genetically distinct species probably exist in other widespread benthic deep-sea asellotes and other Peracarida. Based on existing data we hypothesize that many widespread morphospecies are complexes of cryptic biological species (patchwork hypothesis).

Three expeditions were performed in the framework of ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) in order to understand the Southern Ocean (SO) biodiversity of the Isopoda and to investigate faunal connections with other deep-sea areas in the world oceans. We sampled mainly in the Atlantic sector of the SO (Drake Passage along the Shackleton Fracture Zone, off Elephant Island, in the South Shetland Islands area, in the northwestern Weddell Sea, and at the South Sandwich Islands), but also took two stations in each Bellingshausen Sea and Cape Basin. In total, three expeditions yielded 13,046 specimens of Isopoda. During ANDEEP I–II 5525 specimens and 317 species of Isopoda were sampled, and 7521 specimens and 496 species were discriminated from the ANDEEP III material. Overall, Isopoda comprised 35% of all Peracarida sampled, and we identified 674 isopod species from the 40 deep SO stations. Eighty-nine of these species (13%) were known, the others (585 species) were new to the area, and most of these were new to science, 43 genera being recorded for the first time. Asellota comprised 97% of all ANDEEP Isopoda, and Munnopsidae were the most dominant family, followed by the Desmosomatidae, Haploniscidae, and Ischnomesidae. To our present knowledge 87% of the SO deep-sea Isopoda are apparently “endemic”. Most species did not occur frequently in the samples. Abundance was higher at the shallower ANDEEP stations and highest in the Powell Basin at station 133, and generally decreased with increasing depth. Species richness was highest with 92 species at the bathyal station 80-9 in 3100 m off Kapp Norvegia, in general, species richness was highest at around 3000 m depth with 216 species found at all ANDEEP stations, and 92 species sampled at a single station in 3100 m depth. The cluster analysis of the isopod composition from ANDEEP revealed in general terms that the abyssal Weddell-Sea stations build one cluster. Depth turned out to be the most important abiotic factor for the species composition reported. Most of the species frequently occurring at the abyssal stations are Munnopsidae, which can swim. The SO deep sea differs in faunal composition from the shelf, and few isopod species occur at many stations, while most species only occur at few. The reasons for these findings are unknown. Future studies should focus on the functional role of the frequent species of the SO deep-sea ecosystem and food-web.

A new epibenthic deep-sea genus of Munnopsidae, Gurjanopsis gen. nov., is erected for Munneurycope incisa (Gurjanova, 1946) from the Arctic deep sea and Gurjanopsis australis sp. nov., described from the Weddell Sea, Southern Ocean. The new genus is distinguished by pleotelson broader than the ambulosome, rectangular in dorsal view, with a deep posteromedial notch comprising the anus and the small slender uropods; natasome is large inflated, with thin cuticle; pereonite 7 is longest, as long as pereonites 5 and 6 together. The basis of pereopod 1 is twice as long and as wide as bases of pereopods 2–4; pereopod 7 differs from pereopods 6 and 7 by the stout long distoventral seta and the dorsal row of plumose setae on ischium and the stout merus. The male pleopods 1 and 2 do not operculate the pleopodal cavity completely; pleopod 3 has an enlarged exopod, 1.5 longer than pleopod 2.

We examined deep-sea epibenthic sledge isopod data from the Atlantic sector of the Southern Ocean (SO) (depth range=742–5,191 m). Samples were taken during the expeditions EASIZ II (ANT XV-3) in 1998 and ANDEEP I and II (ANT XIX3/4) in 2002. A total of 471 isopod species were recorded from 28 sites. The species richness of the epibenthic sledge samples was highly variable (6–82 species). Species richness was highest at site 131-3 in 3,053 m depth in the north-eastern Weddell Sea. The highest numbers of species were sampled in the middle depth range and lower species richness was found in the shallower and deeper parts of the study area. Depth is suggested to explain isopod species richness better than both latitude and longitude. Between 58°S and 65°S, the number of species ranged from 9 to 82 (mean=35.9). Further south in the Weddell Sea, between 73°S and 74°S, species richness was lower and the number of species ranged from 6 to 35 (mean=19.2). With regard to longitude, the highest species richness (up to 82 species) was found between 50°W and 60°W in the area of the South Shetland Islands and around the Antarctic Peninsula, while numbers did not exceed 50 species in the eastern Weddell Sea. The haul length, ranging from 807 to 6,464 m, was positively correlated with depth; however, there was no linear relationship between haul length and species richness. We therefore suggest that depth was the most important factor explaining isopod species richness. However, only 28 sites were visited and the statistical power is thus limited. Sampling in the deep sea is expensive and time consuming and as yet this is the best isopod data set available from the Atlantic sector of the SO. Future expeditions are therefore important to better explain the current patterns of benthic diversity in Antarctica.

A review of the Russian deep-sea investigation of Antarctic fauna beginning from the first scientific collection of Soviet whaling fleet expeditions 1946–1952 is presented. The paper deals with the following expeditions, their main tasks and results. These expeditions include three cruises of research vessel (R.V.) Ob in the Indian sector of the Antarctic and in the Southern Pacific (1955–1958); 11 cruises of the R.V. Akademik Kurchatov in the southern Atlantic (November–December 1971); 16 cruises of the R.V. Dmitriy Mendeleev in the Australia–New Zealand area and adjacent water of the Antarctic (December 1975–March 1976); 43 cruises of the R.V. Akademik Kurchatov in the southern Atlantic (October 1985–February 1986); and 43 cruises of the R.V. Dmitriy Mendeleev in the Atlantic sector of the South Ocean (January–May 1989). A list of the main publications on the benthic taxa collected during these expeditions with data of their distribution is presented. The results of Russian explorations of the Antarctic fauna are presented as theoretical conclusions in the following topics: (1) Vertical zonation in the distribution of the Antarctic deep-sea fauna; (2) Biogeographic division of the abyssal and hadal zones; (3) Origin of the Antarctic deep-sea fauna; (4) Distributional pathways of the Antarctic abyssal fauna through the World Ocean.