Rossellidae (Porifera: Hexactinellida) from the Bering Sea and off Bering Island

© INVERTEBRATE ZOOLOGY, 2023Invertebrate Zoology, 2023, 20(1): 57–89 Rossellidae (Porifera: Hexactinellida) from the Bering Sea and off Bering Island K.R. Tabachnick1*, L.L. Menshenina2, H. Ehrlich3 1 P.P.Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Nahimovsky 36, 117997 Russia. 2 Biophysical Department, Physical Faculty, Moscow State University, Moscow, 119992, Russia. 3 Institute of Electronics and Sensor Materials, Technische Universität Bergakademie Freiberg, Freiberg 09599, Germany. * Corresponding author: [email protected] Konstantin Tabachnick ORCID 0000–0002–7669–7233 Larisa Menshenina ORCID 0000–0002–7668–9778 Hermann Ehrlich ORCID 0000–0003–4951–3555 ABSTRACT: Members of the family Rossellidae are the main contributors to the hexactinellid fauna and even to the macrobenthic fauna in the deep waters of the North Pacific. Representatives of this family often reach a larger size than other Hexactinellida, Porifera and even other representatives of benthic invertebrates. Description of Rossellidae from the Bering Sea collected by trawls, submersibles and remotely operated vehicles (ROVs) during the expeditions of RVs ‘Akademik M.A. Lavrentyev’ and ‘Akademik Mstislav Keldysh’ are given. Subgenera, species and subspecies in five genera are described and include: Acanthascus (Acanthascus) alani profundus; A. (Acanthascus) alani microdiscoctasterus ssp.n.; Acanthascus (Rhabdocalyptus) borealis; Acanthascus (Rhabdocalyptus) heteraster; Acanthascus (Rhabdocalyptus) mirabilis; Acanthascus (Staurocalyptus) tylotus; Aulosaccus ijimai; Bathydorus laniger; B. spinosus; B. spinosissimus; B. sp.; Caulophacus (Caulophacus) elegans; C. (Caulophacus) hyperboreus; C. (Caulophacus) miri sp.n.; C. (Caulophacus) subarcticus sp.n.; C. (Caulophacus) sp.; Hyalascus giganteus; H. keldishi sp.n. We suggest a new name B. levis neospinosus ssp.n. for B. levis spinosus of Wilson to avoid the homonymy with B. spinosus Schulze and simultaneously we offer it as a lower synonym of the latter. Meantime B. levis and B. spinosus are considered to be different species. The subdivision of Rossellidae into Rossellinae and Lanuginellinae has no reasonable morphological grounds in their diagnoses anymore and support for uniting these two subfamilies is provided. How to cite this article: Tabachnick K.R., Menshenina L.L., Ehrlich H. 2023. Rossellidae (Porifera: Hexactinellida) from the Bering Sea and off the Bering Island // Invert. Zool. Vol.20. No.1. P.57–89, Suppl. Tables. doi: 10.15298/invertzool.20.1.03 KEY WORDS: Rossellidae, Bering Sea, species and subspecies descriptions, Hexactinellida. Rossellidae (Porifera: Hexactinellida) из Берингова моря и у острова Беринга К.Р. Табачник1*, Л.Л. Меньшенина2, Г. Эрлих3 1 Институт океанологии им. П.П. Ширшова, РАН, Москва, Нахимовский проспект 36, 117997 Россия. 2 Кафедра биофизики, Физический факультет, Московский государственный университет им. М.В. Ломоносова, 119992 Россия. 3 Institute of Electronics and Sensor Materials, Technische Universitдt Bergakademie Freiberg, Freiberg 09599, Germany. * Corresponding author: [email protected] 58 K.R. Tabachnick et al. РЕЗЮМЕ: Губки семейства Rossellidae являются основными представителями Шестилучевых губок и вцелом макробентоса в глубоководной зоне северной части Тихого океана. Эти губки часто достигают значительных размеров среди других Шестилучевых губок, представителей других классов губок и даже других бентосных беспозвоночных. Приводятся описания представителей Rossellidae из Берингова моря и тихоокеанской части острова Беринга собранные тралами, обитаемыми и необитаемыми подводными аппаратами в ходе экспедиций на кораблях “Академик Мстислав Келдыш” и “Академик М.А.Лаврентьев”. Пять родов включают ряд видов, подвидов и подродов: Acanthascus (Acanthascus) alani profundus; A. (Acanthascus) alani microdiscoctasterus ssp.n.; Acanthascus (Rhabdocalyptus) borealis; Acanthascus (Rhabdocalyptus) heteraster; Acanthascus (Rhabdocalyptus) mirabilis; Acanthascus (Staurocalyptus) tylotus; Aulosaccus ijimai; Bathydorus laniger; B. spinosus; B. spinosissimus; B. sp.; Caulophacus (Caulophacus) elegans; C. (Caulophacus) hyperboreus; C. (Caulophacus) miri sp.n.; C. (Caulophacus) subarcticus sp.n.; C. (Caulophacus) sp.; Hyalascus giganteus; H. keldishi sp.n. Новое название B. levis neospinosus ssp.n. предложено для B. levis spinosus Wilson для избегания ононимии с B. spinosus Schulze и одновременно назначается младшим синонимом последнего. В тоже время B. levis и B. spinosus различаются как разные виды. Подразделение Rossellidae на Rossellinae и Lanuginellinae в настоящее время лишено достоверных морфологических оснований, их диагнозы неразличимы, приводятся доводы по ликвидации этих двух подсемейств. Как цитировать эту статью: Tabachnick K.R., Menshenina L.L., Ehrlich H. 2023. Rossellidae (Porifera; Hexactinellida) from the Bering Sea and off the Bering Island // Invert. Zool. Vol.20. No.1. P.57–89, Suppl. Tables. doi: 10.15298/invertzool.20.1.03 КЛЮЧЕВЫЕ СЛОВА: Rossellidae, Берингово море, видовые и подвидовые описания, Hexactinellida. sampled by the ROVs dives during US expeditions. We continue here the description of the Bering Sea hexactinellids collected in its western part, generally from the Piip Volcano, Kommandorsk Basin and off Bering Island. Sponges were sampled by trawls, HOVs ‘Mir-1’ and ‘Mir-2’ during the 22nd cruise of the RV ‘Akademik Mstislav Keldysh’and by the ROV ‘Comanche-8’ during the 75th and 82nd cruises of the RV ‘Akademik M.A. Lavrentyev’. A single hexactinellid representative belonging to a new genus and species — Ijimaiella beringiana from the family Euplectellidae — was described earlier by Tabachnick (2002a). Continued descriptions of new taxa show that our knowledge of these large-sized conspicuous animals is still far from being complete. Reef building hexactinellids of families Farreidae and Euretidae from the Bering Sea are described separately (Tabachnick et al., in press). The representatives of the family Rossellidae, which are the main contributors to the Introduction Investigation of hexactinellid sponges from the Bering Sea started with the description of the US ‘Albatross’ collection in 1888–1890 from the Aleutian Islands (formally outside the Bering Sea (Schulze, 1899). Several other representatives of Hexactinellida from this area were subsequently described by Schulze (1899). In 1906 a series of trawl stations were made by a subsequent ‘Albatross’ expedition in the Bering Sea, off Bering Island, off the Kuril Islands, and off Japan. Specimens collected from these stations were examined and described by Okada (1932). Later investigation of the Bering Sea hexactinellids was connected with the SU expeditions of the RV ‘Vityaz’ and other ships. The results of these expeditions were published by Koltun (1967). Description of hexactinellid sponges from the eastern part of the Bering Sea were published by Stone et al. (2011) and Reiswig and Stone (2013), whose materials were 59Rossellidae from the Bering Sea hexactinellid fauna and even to the entire macrofauna in the North Pacific are described below. Representatives of Rossellidae in the genera Acanthascus and Aulosaccus often reach about half a meter in length. Other species in the genus Caulophacus, have peduncles over 1–1.5 m long. Recently, diverse structural pecularities of Rossellidae (Ehrlich et al., 2008) remain to be also in focus of experts in biomaterials science. Hexactinellids principally have been accepted within this scientific direction as unique sources for biosilica inspired materials chemistry (Ehrlich et al., 2011, 2016) as well as poriferan scaffolding strategies (Tsurkan et al., 2020; Khrunyk et al., 2020). In addition, the recent discovery of actin within skeletal structures of rossellids (Ehrlich et al., 2022) stimulates further research with respect to their morphology, skeletogenesis and structural biology. Material and methods The specimens examined for this paper were collected during the cruise of the RV ‘Akademik Mstislav Keldysh’ voyage 22 with Sigsbee trawls and HOVs ‘Mir’; RV ‘Akademik M.A. Lavrentyev’ voyages 75 and 82 with the ROV ‘Comanche’. The collected materials were preserved in 80–96% alcohol and stored at room temperature. For light microscopy, spicule preparations were made by the method described by Janussen et al. (2004): a K2Cr2O7 solution was made with water (K2Cr2O7 powder: water ˜1:1 vol%) and H2SO4 (96% conc.) was added (K2Cr2O7 solution: H2SO4 ˜1:1 vol%). A dry sponge sample was placed on the microscopic slide; 1–2 drops (depending on sample size) of the K2Cr2O7 solution were added. The microscopic slide was heated (ca. 50–70 °C) for a few minutes to let the solution react. After evaporation of the fluid, the slide was removed from the heat and placed on a cold surface (ca. 20 °C) and a few drops of water were added. The water solution was removed by one or several small pieces of normal filter paper. Water was added again and the spicule carefully stirred by needles, and again filter paper was used to remove excess water (occasionally it was necessary to repeat this procedure several times). The dry preparations were covered by Canada balsam and cover glass. The preparations were examined with a BIOLAR optical microscope with PA–7 camera lucida adopted for it. Abbreviations: avg — average; D, d — diameter; HOV — human-occupied vehicles; IORAS — P.P. Shirshov Institute of Oceanology of Russian Academy of Sciences; L, l — length; max — maximum; min — minimum; n — number of measures; ROV — remotely operated vehicle; RV — research vessel; sta. — station; std — standard deviation. Systematics Rossellidae Schulze, 1885 The latest summary of the early history of Rossellidae and its scope is given by Tabachnick (2002b). This family is in the order Lysaccinosida and was originally subdivided into 3 subfamilies, Rossellinae (characterized by having neither discoctasters nor strobiloplumicomes), Lanuginellinae (characterized by the presence of strobiloplumicomes but no discoctasters), and Acanthascinae (characterized by having discoctasters but no strobiloplumicomes). Tabacknick (2002b) abolished the latter subfamily due to the presence of spicules resembling discoctasters in the holotype of the type species for the genus Caulophacus — C. (Caulophacus) latus. This genus together with Caulophacella was later moved from the Rossellinae to the Lanuginellinae (Dohrmann et al., 2017; Reiswig et al., 2021). Reiswig and Stone (2013) resurrected the subfamily Acanthascinae, arguing that discoctasters were only found in the three genera within that group, without comment on the possible presence of these distinctive spicules in the genus Caulophacus. However, we continue to adhere to contend that the abolishment of the subfamily Acanthascinae is appropriate and suggest consideration of its tree genera status in the lower subgeneric level. As for the two remnant subfamilies of Rossellidae, the only morphological reason for the subdivision of this family was absence in Rossellinae and presence in Lanuginellinae of specific spicules — strobiloplumicomes. The genetic monophyletic charecters of these grpoops sudgested by Dohrmann et al. (2017) are not supported by any common morphological features sutable for the separate diagnoses of these two subfamilies. Inspite that the genetic analysis of Lanuginellinae supports keeping this subfamily no relible morphological features could be established to be valid for the diagnosis, which provides its definition from Rossellinae. A weak feature of this subdivision is connected with two facts. The first: absence of a peculiarity (in this case strobiloplumicomes in Rossellinae) is a principally weak taxonomic feature, being alone it does not provide reliable ground for the taxon’s characterization – absence of a feature may be a result of multiple loses of it, or the feature has not appeared at all, thus the possibility of a polyphyletic origin of the taxon with such character is highly likely. And the second: strobiloplumicomes were not found in some specimens of monospecific Mellonympha — M. vellata (a doubtful Lanuginellinae representative) (Tabach- 60 K.R. Tabachnick et al. Fig. 1. Acanthascus (Acanthascus) alani microdiscoctasterus ssp.n. Complete specimen before ROV ‘Comanche’ sampling. Рис. 1. Acanthascus (Acanthascus) alani microdiscoctasterus ssp.n. Целый экземпляр перед взятием образца подводным роботом “Comanche”. high with 2 oscula about 80 mm in diameter. The sponge was attached to rocky substratum; its basal part is about 100 mm in diameter. Some irregular prostalia diactins are observed, they are generally oscularia but some of these spicules are lateralia. The walls of this specimen are up to 25–30 mm in thickness. Only a portion, about 100x100 mm and 10–25 mm in thickness, from the upper part of this sponge was sampled, a largest portion of the holotype specimen was left on the bottom alive. The collected material was reduced to many lamellate fragments during the fixation and transportation. SPICULES. MEGASCLERES. Choanosomal spicules are diactins with stout, smooth shafts, and rounded, rough outer ends. These diactins are 1.4–4/ 0.004–0.013 mm. Several hypodermal pentactins with smooth and spiny tangential rays were found among the spicule preparations, they likely belong to other representatives of Acanthascus numerously distributed around this specimen. Dermalia and atrialia are very similar, both consisting of pentactins, hexactins, some stauractins and rare diactins with short-spiny rays and rounded outer ends. Most pentactins and some stauractins have tuberculated rudiments of the absent rays. The only difference between dermal and atrial spicules is the dominance of pentactins in the dermal sides of the colony and hexactins in the atrial sides. Dermal pentactins have tangential rays 0.081–0.196 mm long (n=25, avg: 0.150 mm, std: 0.029 mm), the proximal rays 0.104– 0.233 mm long (n=25, avg: 0.169 mm, std: 0.032 mm), and rudiments of the distal ray if present 0.007–0.019 mm long (n=19, avg: 0.011 mm, std: nick, 2002b). Now the new phylogenetic data led to the transferring of the genus Caulophacus (it is unclear complete (with numerous subgenera) or only a part of it) and suggestion of a new diagnosis for Lanuginellinae (Reiswig et al., 2021). This operation is a final point in the disappearance of the last reliable differences between the two remaining subfamilies and this fact requires the final formal action of the entire abolishment of discussed subfamilies. Thus Rossellidae now is an integral family, which has no subdivision into subfamilies. Meantime the fact of presence or absence of specific microscleres: discoctasters (former specific feature of Acanthascinae abolished by Tabachnick (2002b)) and presence of strobiloplumicomes (specific feature of former Lanuginellinae) can be definitely used in keys to genera and subgenera of numerous rossellid taxa in corresponding chapters suggested by Tabachnick (2002b) following the insubstantial (as it is obvious now) subdivision into groups. Acanthascus Schulze, 1886 Acanthascus (Acanthascus) alani Ijima, 1898 Acanthascus (Acanthascus) alani microdiscoctasterus ssp.n. Figs 1, 2; Suppl. Tab. 1. MATERIAL. Holotype: IORAS 5/2/3805. RV ‘Akademik M.A. Lavrentyev’ – 75, ROV ‘Comanche’, sta. 18, spec. 5-2, 55.4352° N 167.2668° E, 1420 m. DESCRIPTION. BODY. Funnel-like body with smooth dermal and atrial surfaces, about 500 mm 61Rossellidae from the Bering Sea Fig. 2. Spicules of Acanthascus (Acanthascus) alani microdiscoctasterus ssp.n., holotype. A — dermal stauractin. B — dermal hexactin. C — dermal pentactin. D — dermal diactin. E–F — choanosomal diactins and their outer ends. G–J — discoctasters. K — primary rosette of discoctaster, secondary rays not developed. L — secondary ray of discoctaster. M–N — spherical microdiscohexasters. O — stellate microdiscohexaster. P–T — oxyoidal microscleres. U — primary rosette and secondary ray of oxyoidal microsclere. Рис. 2. Спикулы Acanthascus (Acanthascus) alani microdiscoctasterus ssp.n., голотип. A — дермальная стаурактина. B — дермальная гексактина. C — дермальная пентактина. D — дермальная диактина. E–F — хоаносомальные диактины и их концевые элементы. G–J — дискоктастры. K — первичная розетка дисоктастра, вторичные лучи не развиты. L— вторичные лучи дискоктастра. M–N — сферические микродискогексастры. O — звездчатый микродискогексастр. P–T — оксиоидные микросклеры. U — первичная розетка и вторичные лучи оксиоидной микросклеры. 62 K.R. Tabachnick et al. 0.002 mm). The diameter of these rays is 0.009– 0.015 mm. Dermal hexactins have rays of equal length 0.159–0.252 mm long (n=3, avg: 0.201 mm, std: 0.047 mm). Stauractins have tangential rays 0.137–0.189 mm long (n=3, avg: 0.158 mm, std: 0.027 mm), their rudimental tubercles if present are 0.007–0.015 mm long (n=3, avg: 0.012 mm, std: 0.004 mm). Some unique diactins have rays about 0.222 mm long with a widening in the middle. Atrial pentactins have tangential rays 0.085–0.178 mm long (n=13, avg: 0.144 mm, std: 0.024 mm), the ray directed inside the body is 0.074–0.204 mm long (n=13, avg: 0.145 mm, std: 0.033 mm), the rudiment of the distal ray if present is 0.007–0.019 mm long (n=13, avg: 0.010 mm, std: 0.003 mm), the diameter of these rays is 0.010–0.011 mm. Atrial hexactins have rays 0.104–0.326 mm long (n=26, avg: 0.170 mm, std: 0.046 mm). Atrial stauractins have tangential rays 0.111–0.144 mm long (n=3, avg: 0.132 mm, std: 0.018 mm), their rudimental tubercles if present are 0.011–0.015 mm long (n=4, avg: 0.013 mm, std: 0.002 mm). MICROSCLERES. Discoctasters are common and rare discomultiasters are present in this species. Unlike discohexasters, discomultiasters have more than 8 tufts of secondary rays — up to 11, sometimes these additional secondary rays have a single secondary ray, but usually they have 2–8 secondary rays in a tuft. The secondary rays of discoctasters have spiny shafts. Some discoctasters have a specific shape with 4 secondary ray tufts located in one plane distributed at about 90 degree to each 4 other secondary ray tufts which are similar to the former ones are situated below it. Some discoctasters without developed secondary rays were found. The discohexasters are 0.036–0,079 mm in diameter (n=25, avg: 0.061 mm, std: 0.010 mm), their primary rosette is 0.025– 0.050 mm in diameter (n=25, avg: 0.038 mm, std: 0.007 mm). Spherical discohexasters with numerous secondary rays are 0.023–0.036 mm in diameter (n=20, avg: 0.028 mm, std: 0.003 mm), their primary rosette is 0.006–0.014 mm in diameter (n=20, avg: 0.009 mm, std: 0.002 mm). An occasional spherical discohexaster is 0.065 mm in diameter with primary rosette 0.011 mm in diameter. A unique stellate discohexaster was also found with 3–4 secondary rays 0.054 mm in diameter with the primary rosette 0.027 mm in diameter. Oxyoidal microscleres are very fragile and in the spicule preparations they were usually broken with their primary rosettes and secondary rays separated. The secondary rays (1–3 in number, but sometimes up to 7) have finest part at base what provides the effect described above, they are covered by numerous spines directed towards the spicular center especially at their basal part. Many oxyoidal microscleres have secondary rays of different length. The oxyoidal microscleres included oxyhexasters, oxyhemihexasters (most of these two forms should be rather called anysooxyhexasters and anysooxyhemihexasters) and hexactins. The oxyhexasters and oxyhemihexasters are 0.067–0.281 mm in diameter (n=26, avg: 0.139 mm, std: 0.035 mm), their primary rosette is 0.008–0.022 mm in diameter (n=20, avg: 0.013 mm, std: 0.003 mm). A unique oxyhexaster was 0.027 mm in diameter with primary rosette 0.009 mm in diameter. The oxyhexactins are 0.126–0.154 mm in diameter (n=7, avg: 0.154 mm, std: 0.025 mm). REMARKS. In the presence of the set of dermal spicules and fragile oxyoidal microscleres when such spicules easily split to primary and secondary rays the new subspecies is similar to two previously described subspecies: A. (Acanthascus) alani alani Ijima, 1898 and A. (Acanthascus) alani profundus Koltun, 1967. The differences are in the sizes of discoctasters, the presence of discomultiasters and in the similarity between dermal and atrial spicules in the new subspecies (in previously described subspecies atrialia are generally hexactins). Hypodermal pentactins with smooth and spiny tangential rays found in the new subspecies are considered to have allochthonous origin but meantime they point the close affinities between tree subgenera of Acanthascus which taxonomic status was downgraded by Tabachnick (2002b). It is very likely, that these subspecies should be raised to the species level but due to the historical tradition and comfort in identification of multispecific taxon Acanthascus its taxonomic position is preserved at the moment. A question of rising of the status of all the described subspecies to specific level requires futher investigations. ETYMOLOGY. The subspecies name reflects the characteristically small size of discoctasters. DISTRIBUTION. Currently found only at the Piip Volcano slope, Bering Sea, at 1420 m depth. Acanthascus (Acanthascus) alani profundus Koltun, 1967. Figs 3, 4; Suppl. Tab. 2. SYNONYMY. Acanthascus alani profundum Koltun, 1967: 93. MATERIAL. IORAS 5/2/3830, 3831: RV ‘Akademik M.A. Lavrentyev’ – 75, ROV ‘Comanche’, sta. 9, spec. 2-3 and 2-4 correspondingly, 55.4282° N 167.2772° E, 986 m. IORAS 5/2/3835: RV ‘Akademik M.A. Lavrentyev’ – 75, ROV ‘Comanche’, sta. 9, spec. 1, 55.4282° N 167.2772° E, 984 m. DESCRIPTION. BODY. The specimens are saccular: IORAS 5/2/3835 — 600 mm high, diameter of the osculum is approximately 250 mm (a fragment of this specimen was sampled, it measures 180 mm high, 100 mm in maximal diameter of the osculum, 63Rossellidae from the Bering Sea Fig. 3. Acanthascus (Acanthascus) alani profundus, a ROV ‘Comanche’ photo of the specimen IORAS/ 5/2/3826. The arrow shows sampled fragment. Рис. 3. Acanthascus (Acanthascus) alani profundus, фотография выполненая подводным роботом “Comanche” образца IORAS/5/2/3826. Стрелка показывает на взятый фрагмент. Fig. 4. Acanthascus (Acanthascus) alani profundus, external shape. Scale 50 mm. A — two specimens: large — IORAS/5/2/3830: small — IORAS/5/2/3831. B-C — view from different sides IORAS/5/2/3826. Рис. 4. Acanthascus (Acanthascus) alani profundus, внешний вид. Масштаб 50 мм. A — два экземпляра: большой — IORAS/5/2/3830; маленький — IORAS/5/2/3831. B-C — вид с разных сторон IORAS/5/ 2/3826. the walls are 10–15 mm in thickness); 5/2/3830 — 180 mm high, 100 mm in diameter, the walls are 8– 10 mm in thickness; 5/2/3831 — 110 mm high, 40 mm in diameter, the walls are 5 mm in thickness. The latter two specimens are attached to each other by their basal parts; their atrial cavities are not common. Prostalia lateralia are diactins which protrude at 10– 45 mm over the dermal surface. REMARKS. Despite some notable differences in spicule sizes of dermal and atrial spicules and the presence of microdiscohexasters the newly found specimens are assigned to Acanthascus (Acanthascus) alani profundus Koltun, 1967 first of all owing to the presence of two size classes of discoctasters. Another type of spicules found in the new specimens is microdiscohexaster. Quite probably that the differences between our specimens and the original description of the subspecies is a result of that only a small fragment of a sponge was studied initially (Koltun, 1967). All other spicules show a similar type in the variations described earlier and in newly found specimens. It is very likely that A. (Acanthascus) alani profundus should be synonymized with A. (Acanthascus) platei Schulze, 1899, but it requires a significant revision since the largest discoctasters are dermal and the smallest are atrial (unlike A. (Acanthascus) alani profundus). Another species with a notable difference in dermal and atrial discoctasters is A. (Acanthascus) cactus, but unlike the specimens discussed above this species has generally dermal stauractins and atrial pentactins. DISTRIBUTION. Bering Sea, at 984–2440 m depth. 64 K.R. Tabachnick et al. mal pentactins (their tangential rays) are 10–15 mm over the dermal surface. The hypodermal pentactins are most parathropal with spiny tangential rays. REMARKS. Differences between the new and previousely described specimens of A. (Rhabdocalyptus) borealis (Okada, 1932; Koltun, 1967) are given in the Suppl. Tab. 3. The most important of them: no microdiscohexasters in all investigated specimens were observed; smaller diameter of the oxyoidal microscleres; the ray of atrial hexactin may be notably smaller. Nevertheless these features are considered to be intraspecific, they are widening the species limits. Morever, the specimen described by Koltun (1967) has some additional intermediate parameters. DISTRIBUTION. Bering Sea, Pacific side of Kuril Islands, at 440–2849 m depth. Acanthascus (Rhabdocalyptus) heteraster Okada, 1932 Fig. 6; Suppl. Tab. 4. MATERIAL. IORAS 5/2/3824: RV ‘Akademik M.A. Lavrentyev’ – 75, ROV ‘Comanche’, sta. 21, spec. 4, 55°28′58.8″ N 167°15′30.6″ E, 2849 m. DESCRIPTION. BODY. The preserved specimen is tubular, about 90 mm high, 50 mm in maximal diameter; the walls are 1–3 mm thick. Prostalia lateralia are hypodermal orthotropal (rarely parathFig. 5. Acanthascus (Rhabdocalyptus) borealis, external shape. Scale 50 mm. A — IORAS/5/2/3827. B — IORAS/5/2/3814. C — IORAS/5/2/3808. Рис. 5. Acanthascus (Rhabdocalyptus) borealis, внешний вид. Масштаб 50 мм. A — IORAS/5/2/3827. B — IORAS/5/2/3814. C — IORAS/5/2/3808. Acanthascus (Rhabdocalyptus) Schulze, 1886 Acanthascus (Rhabdocalyptus) borealis Okada, 1932 Fig. 5; Suppl. Tab. 3. MATERIAL. IORAS 5/2/3827: RV ‘Akademik M.A. Lavrentyev’ – 75, ROV ‘Comanche’, sta. 18, spec. 3-1, 55.4382° N 167.2652° E, 1569 m. IORAS 5/2/3808; 3814: RV ‘Akademik M.A. Lavrentyev’ – 75, ROV ‘Comanche’, sta. 9, spec. 2-5 and 2-2 correspondingly, 55°28′58.8″ N 167°15′30.6″ E, 2849 m. DESCRIPTION. BODY. The biggest specimen is IORAS 5/2/3827: 160 mm high, 60 mm in maximal diameter (close to the osculum); walls are 2–6 mm thick. Prostalia oscularia are diactins which protrude up to 20 mm over the osculum, prostalia lateralia are hypodermal pentactins which make a dense cover up to 15 mm above the dermal surface. Other specimens are smaller: IORAS 5/2/3814: 60 mm high, 20 mm in diameter in the middle and 15 mm in diameter of the osculum, the walls are 1–1.5 mm thick; IORAS 5/2/3808: 50 mm high, 25 mm in diameter in the middle and 20 mm in diameter of the osculum, the walls are 2–3 mm thick. Prostalia in the small specimens is smaller: oscularia diactins protrude up to 15–20 mm, prostalia lateralia of hypoderFig. 6. Acanthascus (Rhabdocalyptus) heteraster, external shape. Scale 10 mm. A — view from dermal side. B — view from atrial side. Рис. 6. Acanthascus (Rhabdocalyptus) heteraster, внешний вид. Шкала 10 мм. A — вид с дермальной стороны. B — вид с атриальной стороны. 65Rossellidae from the Bering Sea ropal) spiny pentactins irregularly distributed and protruding 1–4 mm over the dermal surface. REMARKS. The newly found specimen has spicules size parameter different from those of the type specimen described by Okada (1932) (see the Suppl. Tab. 4). The long ray of atrial hexactins (directed into the atrial cavity) in the new specimen is notably longer then those in previouse descriptions; discoctasters are of a single type and their minimal size is less than that in the type specimen and larger than the minimal size of this type of microsclere in a specimen described by Koltun (1967). The discoctasters in the new specimen are notably larger than the same type of discoctasters in the initial description, microdiscohexasters are absent and oxyoidal microscleres reach larger sizes. Nevertheless most spicule parameters of this new specimen correspond to A. (Rhabdocalyptus) heteraster much more then to other species of the subgenus and it seem more reasonable to expand the spicule parameters in the previous species then to create a new one. DISTRIBUTION. Bering Sea, off Pacific coast of Canada, 445–2849 m depth. Acanthascus (Rhabdocalyptus) mirabilis Schulze, 1899 Suppl. Tab. 5. MATERIAL. IORAS 5/2/3826: RV ‘Akademik M.A. Lavrentyev’ – 75, ROV ‘Comanche’, sta. 17, spec. 3, 55.4599° N 167.269° E, 2279 m. DESCRIPTION. BODY. The specimen IORAS 5/2/3826 is a fragment of the 5–10 mm thick upper wall of the sponge. Prostalia oscularia and lateralia of large diactins protrude at 20–35 mm over the osculum margin. Prostalia of hypodermal pentactins protrude at about 10 mm over the dermal surface. The diameter of the osculum is about 80 mm in diameter (reconstructed). Hypodermal pentactins of both orthotropal and parathropal types have spiny or smooth tangential rays. REMARKS. The new specimen agrees with the description of specimens of Rhabdocalyptus mirabilis (Reiswig et al., 2013) except for the absence of microdiscohexasters. Both these specimens have floricoidal discoctasters that differ from those in the original description of this species (Schulze, 1899) while they have floricoidal discoctasters. The discs of floricoidal discoctasters are assymetrically attached to the secondary ray, while in the original description they are completely symmetrical. Spicules with assymetrical features are also known in: A. (Rhabdocalyptus) unguiculatus (Ijima, 1904) — a similar species with predomination of oxyhexasters and oxyhemihexasters over the oxyhexactins. This specimen also differs from A. (Rhabdocalyptus) gomezei (Tabachnick et al., 2019), a species with notable amount of dermal stauractins, and A. (Rhabdocalyptus) bidentatus — stauractins predominate in this species and secondary rays of discoctasters have 2 teeth (Okada, 1932). DISTRIBUTION. Off S of Alaska Peninsula, Bering Sea, 1143–2311 m depth. Fig. 7. Acanthascus (Staurocalyptus) tylotus, a ROV ‘Comanche’ photos. A — two specimens before capturing surrounded by numerous specimens of Farrea sp. A — IORAS 5/2/3832 – a smaller specimen, to the left; IORAS 5/2/3807 – a bigger specimen, to the right. B — magnified portion of the specimen IORAS 5/2/3807). Рис. 7. Acanthascus (Staurocalyptus) tylotus, фотография подводного робота “Comanche”. A — два экземпляра перед поимкой, окруженные многочисленными представителями Farrea sp. A — IORAS 5/2/3832 – маленький экземпляр, слева; IORAS 5/2/3807 – больший экземпляр, справа. B — увеличенный фрагмент образца IORAS 5/2/3807). 72 K.R. Tabachnick et al. Fig. 12. Spicules of Bathydorus spinosus, IORAS 5/2/3809 (additional types to previous descriptions). A — small oxyhexaster. B — large oxyhexaster. C — oxyhexactin. D, E, G — abnormal oxyoidal microscleres. F — oxyhemihexaster. Рис. 12. Спикулы Bathydorus spinosus, IORAS 5/2/3809 (в дополнение к предыдущим описаниям). A — маленикий оксигексастр. B — большой оксигексастр. C — оксигексактина. D, E, G — анормальные оксиоидные микросклеры. F — оксигемигексастр. Fig. 13. Spicules of Bathydorus sp., IORAS 5/2/ 3838. A–B — dermal stauractins. C — oxyhemihexaster. D — oxyhexactin. Рис. 13. Спикулы Bathydorus sp., IORAS 5/2/ 3838. A–B — дермальные стаурактины. C — оксигемигексастр. D — оксигексактина. SPICULES. MEGASCLERES. Hypodermal (and hypoatrial pentactins as well), rarely stauractins with conically pointed, rough outer ends. The tangential rays of these pentactins are 0.3–1.0 mm long, the ray directed inside the body is 0.5–1.0 mm long, these rays are 0.009–0.034 mm in diameter. Choanosomal diactins 2.3–3.7/0.008–0.014 mm have stout shafts or with a widening in the middle with rounded, rough outer ends. Dermalia and possibly atrialia are stauractins, rarely tauactins. They have slightly rough rays with conically pointed or rounded outer ends. The rays of these stauractins are 0.085–0.344 mm in diameter (n=27, avg: 0.192 mm, std: 0.065 mm), the diameter of these rays is 0.004–0.013 mm. MICROSCLERES. Oxyoidal microscleres have very thin rays. They are usually oxyhexasters and oxyhemihexasters with 1–3 secondary rays, often curved or sometimes oxyhexactins. The diameter of oxyhexasters is 0.144–0.237 mm (n=25, avg: 0.170 mm, std: 0.020 mm), the diameter of their primary rosette is 0.007–0.015 mm (n=25, avg: 0.008 mm, std: 0.002 mm). The diameter of oxyhexactins is 0.148– 0.215 mm (n=8, avg: 0.175 mm, std: 0.021 mm). 73Rossellidae from the Bering Sea Fig. 14. Caulophacus (Caulophacus) elegans, external shape from different sizes. Scale 50 mm. A — IORAS 5/2/2152. B — IORAS 5/2/2147. C — IORAS 5/2/2216. D — IORAS 5/2/2187. Рис. 14. Caulophacus (Caulophacus) elegans, внешний вид с разных сторон. Масштаб 50 мм. A — IORAS 5/2/2152. B — IORAS 5/2/2147. C — IORAS 5/2/2216. D — IORAS 5/2/2187. Caulophacus (Caulophacus) elegans Schulze, 1886 Figs 14, 15; Suppl. Tab. 11. SYNONYMY: Caulophacus elegans Schulze, 1885: 438, fig. 159 — nomen nudum in the fig. footnote; 1886: 46; 1887: 126; Koltun, 1967: 118. MATERIAL. IORAS 5/2/2147: RV ‘Akademik Mstislav Keldysh’ – 22, sta. 2309, trawl, N off the Bering Island, 55°13.24–12.02′ N 167°29.07–26.7′ E, depth 3957–3978 m. IORAS 5/2/2151; 2152; 2155; 2157; 2158.1; 2162; 2164; 2167; 2168; 2169; 2172; 2173; 2174; 2175; 2179; 2180; 2180.1; 2184; 2185; 2186; 2187; 2191; 2194; 2195; 2199; 2202; 2204; 2207; 2208; 2210; 2211; 2212; 2214; 2216; 2218; 2236; 2245; 2260; 2261; 2269; 2275; 2296; 2299; 2306; 2308: RV ‘Akademik Mstislav KeldyREMARKS. Among the species of Bathydorus only B. servatus Topsent, 1927 (1928) has similar oxyoidal microscleres with such thin rays. But dermal stauractins are much smaller as well as oxyoidal microscleres are also smaller in the newly found material, besides dermal diactins are absent (unlike B. servatus). Based on a small fragment, description of a new species does not seem reasonable, moreover, the spicule content may be not complete and thus the generic identification is also not perfect. Spicules of other hexactinellids — Farrea and Periphragella were also found in investigated spicule preparations so the specimen is obviously contaminated by foreign spicules. Caulophacus Schulze, 1886 Caulophacus (Caulophacus) Schulze, 1886 74 K.R. Tabachnick et al. Fig. 15. Spicules of Caulophacus (Caulophacus) elegans. A — dermal hexactin. B — atrial hexactin. C– D — dermal or atrial pentactins: C — smooth; D — with spines on the rays close to the spicule center. E — choanosomal hexactin. F–H — choanosomal diactins. I — spiny spherical discohexaster. J — abnormal spiny discohexaster. K–O — lophodiscohexasters: O — anysolophodiscohexaster. P — lophodiscodiaster. A–J; L; N–O — IORAS 5/2/2152. K; M; P — IORAS 5/2/2147. Рис. 15. Спикулы Caulophacus (Caulophacus) elegans. A — дермальная гексактина. B — атриальная гексактина. C–D — дермальные или атриальные пентактины: C — гладкая; D — с шипами на основаниях лучей. E — хоаносомальная гексактина. F–H — хоаносомальные диактины. I — шиповатый сферический дискогексастр. J — аномальный шиповатый дискогексастер. K–O — лофодискогексастеры. O — анизолофодискогексастер. P — лофодискодиастер. A–J; L; N–O — IORAS 5/2/2152. K; M; P — IORAS 5/2/2147. 75Rossellidae from the Bering Sea sh’ – 22, sta. 2316, trawl, N off the Bering Island, 55°36.08–35.00′ N 167°23.04–24.46′ E, depth 4200– 4294 m. DESCRIPTION. BODY. The specimens have a mushroom shaped body typical for Caulophacus. Some specimens however are just fragments. Discoidal bodies are from 33 to 200 mm in diameter, 1.5–10 mm in thickness, with undulating edges of discs. Peduncles are tubular 2.5–20 mm in diameter. SPICULES. MEGASCLERES. Hypodermalia and hypoatrialia are pentactins with rays having smooth and rounded outer ends or they have tubercles or numerous tubercles on the shafts close to the spicular center. The tangential rays of hypodermal and hypoatrial pentactins are 0.3–0.6 mm long, the ray directed inside the body is 0.5–0.7 mm long, these rays are 0.017–0.038 mm in diameter. Choanosomal spicules are diactins and hexactins. Choanosomal diactins usually have a widening in the middle, sometimes four rudimental tubercles or they are stout, their outer ends are rounded and rough. Choanosomal diactins are 1.1–1.5/0.005–0.011 mm. The diactins of the peduncle are 0.019–0.022 mm in diameter; they are connected by numerous synapticular junctions. Choanosomal hexactins have smooth rays with rounded outer ends, that are 0.45–0.9/ 0.023–0.044 mm in length. Dermalia and atrialia are similar to each other in shape and generally in size. They are hexactins which have rays directed outside the body. Rays are pinular and smooth or slightly covered by tubercles; other rays have rounded or conically pointed, rough outer ends. Rarely dermal and atrial spicules are pentactins with a rudimental tubercle situated in place of the ray directed inside the body. The pinular ray of dermal hexactins is 0.096–0.248 mm long, tangential rays are 0.067–0.141 mm long, the ray directed inside the body is 0.048–0.137 mm long, the diameter of these rays is 0.007–0.011 mm; the diameter of the pinular part is 0.037–0.044 mm. The pinular ray of atrial hexactins is 0.111–0.340 mm long, tangential rays are 0.067–0.144 mm long, the ray directed inside the body is 0.037–0.118 mm long, the diameter of these rays is 0.007–0.009 mm; the diameter of the pinular part is 0.026–0.037 mm. MICROSCLERES. Obviously two types of discoidal microscleres are known in these specimens. Some oxyoidal microscleres but likely they belong to other hexactinellids from close locations. Discohexasters have short principal rays, the rays are spiny and usually they have 5–6 secondary rays, rarely 1. Abnormal discohexasters are rare. The discohexasters are 0.086–0.151 mm in diameter with primary rosette 0.011–0.036 mm in diameter. Lophodiscohexasters often have tubercles carrying some additional discoidal rays on the smooth shafts; sometimes the secondary rays are of different sizes (lophoanysodiscohexasters). The secondary rays of large lophodiscohexasters are short–spiny, in small spicules they look to be smooth and even sometimes tyloidal in shape (not completely developed). The number of secondary rays is from 4 to about 30. Rarely lophodiscodiasters were found. Lophodiscohexasters are referred to a single size class of spicules in spite the significant size variation. The gap of their size classes was observed in some specimens but in other the gap is different and in some completely absent. The diameter of lophodiscohexasters is 0.047–0.324 mm with primary rosette 0.022– 0.144 mm in diameter. The largest lophodiscohexaster was found in the specimen 5/2/2168 — 0.324 mm in diameter with the primary rosette 0.108 mm in diameter what is close to that described by Koltun (1967) (0.330 mm in diameter) which he considered to have allochthonic origin. REMARKS. As it was observed, the specimens of different sizes: small and big (Suppl. Tab. 11) have very similar sizes of spicules. Moreover, Table 11 shows that the smallest specimen 5/2/2187 has the most spicules of larger sizes than larger specimens. Among numerous species of Caulophacus (Caulophacus) the newly found materials are most of all similar to C. (Caulophacus) elegans in the presence of discohexasters (unlike discohexactins), shape of most spicules, but unlike the previously known species it has dissimilar dermal and atrial pinular hexactins. The dermal hexactins are smaller than the atrial ones in C. (Caulophacus) elegans and generally equal in the new specimens from the Bering Sea. DISTRIBUTION. Bering Sea, E of Japan, 3680– 4220 m. Caulophacus (Caulophacus) hyperboreus Koltun, 1967 Figs 16–18; Suppl. Tab. 12. MATERIAL. IORAS 5/2/2084; IORAS 5/2/ 2153; 2154; 2161.1; 2228.1; 2229; 2231; 2232; 2233; 2234: RV ‘Akademik Mstislav Keldysh’ – 22, sta. 2309, trawl, N off the Bering Island, 55°13.24– 12.02′ N 167°29.07–26.7′ E, 3957–3978 m. IORAS 5/2/2150; 2158; 2177; 2178; 2182; 2183; 2183.1; 2217: RV ‘Akademik Mstislav Keldysh’ – 22, sta. 2316, trawl, N off the Bering Island, 55°36.08– 35.00′ N 167°23.04–24.46′ E, 4200–4294 m. IORAS 5/2/3811; 3811.2–3811.9; 3820, 3821: RV ‘Akademik M.A. Lavrentyev’ – 75, sta. 22, ROV ‘Comanche’, 55°30′36.1″ N 167°19′27.1″ E, 3879– 3578 m. DESCRIPTION. BODY. The specimens had mushroom-like bodies or fragments often attached to a peduncle branching into many separate bodies. It is not obvious if they represent a single specimen 76 K.R. Tabachnick et al. Fig. 16. Specimens of Caulophacus (Caulophacus) hyperboreus attached to a dead skeleton of Periphragella (not visible here). A ROV ‘Comanche’ photo. RV ‘Akademik M.A. Lavrentyev’ – 75, sta. 22, 55°30′36.1″ N 167°19′27.1″ E, depth 3879– 3578 m. Рис. 16. Экземпляры Caulophacus (Caulophacus) hyperboreus прикрепленные к мертвому скелету Perifragella (не виден). Фотография подводного робота “Comanche”; НИС “Академик М.А. Лаврентьев” – 75, станция 22, 55°30′36.1″ N 167° 19′27.1″ E, глубина 3879–3578 м. Fig. 17. Specimens of Caulophacus (Caulophacus) hyperboreus: A — IORAS 5/2/2232. B — IORAS 5/ 2/2250, view from different sides. C — IORAS 5/2/2661, view from different sides. Scale 10 mm. Рис. 17. Экземпляры Caulophacus (Caulophacus) hyperboreus: A — IORAS 5/2/2232. B — IORAS 5/ 2/2250, вид с разных сторон. C — IORAS 5/2/2661, вид с разных сторон. Масштаб 10 мм. 77Rossellidae from the Bering Sea Fig. 18. Spicules of Caulophacus (Caulophacus) hyperboreus, IORAS 5/2/2229 (additional types to previous descriptions). A — dermal pinular hexactin. B — dermal pinular pentactin. C — atrial pinular hexactin. D — atrial pinular pentactin. Рис. 18. Спикулы Caulophacus (Caulophacus) hyperboreus, IORAS 5/2/2229 (в дополнение к предыдущим описаниям). A — дермальная пинулярная гексактина. B — дермальная пинулярная пентактина. C — атриальная пинулярная гексактина. D — атриальная пинулярная пентактина. with stolonial branching or multiple organisms of same species that settled on the peduncle of one colony. The specimen sizes ranged from those with the disc 3 mm in diameter and 1 mm in thickness with peduncle 1 mm in diameter to the biggest ones 55 mm in diameter, 3–4 mm in thickness and the peduncle about 5 mm in diameter. But some of them reach even larger sizes — a single lamellate fragment of the discoidal body 90x70 mm and 4–6 mm in thickness was found. REMARKS. The species was originally described as a subspecies: Caulophacus schulzei hyperboreus Koltun, 1967. Both species from the North Pacific, C. (Caulophacus) schulzei and C. (Caulophacus) elegans, are completely different from the subspecies described by Koltun (1967). Among the newly found specimens of Caulophacus hyperboreus many had pinular pentactins among both dermal and atrial hexactins sometimes in large amounts. As it is seen from the Suppl. Tab. 12, it can be assumed that spicule combination and their sizes are very similar between investigated specimens and dissimilarities are considered as an inerspecific variation. Unlike specimens described by Koltun, some specimens from the new series from the Bering Sea have dermal and atrial pinular pentactins with their rudimentary ray directed inside the body, in some specimens they are even more numerous then corresponding hexactins (for instance, IORAS5/2/2229; 2232 and some other specimens). Meantime, the other spicules correspond in shape and size to typical representatives and these specimens are undoubtedly belonging to the same species. DISTRIBUTION. Bering and Okhotsk Seas, 3400–4294 m depth. Caulophacus (Caulophacus) miri sp.n. Figs 19, 20. MATERIAL. HOLOTYPE. IORAS 5/2/2054. RV ‘Akademik Mstislav Keldysh’ – 22, sta. 2296, HOV ‘Mir-1’, Pacific side of Bering Island, 54°57.7′ N 165°42.85′ E, 5952 m. DESCRIPTION. BODY. The specimen is fungus-like with a discoidal ovoid body 140x190 mm and 20 mm thick, the edge of the disc is everted down so that the atrial surface present also on the lateral edge of the discoidal body. The tubular peduncle was broken into several pieces during collection but was 180 mm long with walls 5 mm in thickness. The upper part of the peduncle is 20x25 mm in diameter while the lower part is about 20 mm in diameter. SPICULES. MEGASCLERES. Choanosomal spicules are diactins and hexactins. The diactins are sometimes thick but most were thin. The thick diactins have stout shafts and rounded outer ends, they are 2–2.7/0.032–0.110 mm. The thin diactins have stout shafts, sometimes with a widening in the middle or four tubercle rudiments, their outer ends are rounded, smooth or rough, they are 1.5–1.9/0.008– 0.024 mm. Choanosomal hexactins have rays 0.4– 1.6/0.015–0.1 mm with conically pointed outer ends. Hypodermalia and hypoatrialia are pentactins with conically pointed outer ends. Tangential rays of these pentactins are 0.2–1.4 mm long, the ray directed inside the body 0.1–0.8 mm long, their diameter 78 K.R. Tabachnick et al. Fig. 19. Caulophacus (Caulophacus) miri sp.n., holotype, external shape from different sides. Scale 50 mm. Рис. 19. Caulophacus (Caulophacus) miri sp.n., голотип, внешний вид сразных сторон. Масштаб 50 мм. mm), the diameter of pinular ray is 0.019–0.033 mm at base and 0.041–0.063 mm in maximal mediate part, the diameter of other rays is 0.015–0.019 mm at base. The pinular ray in atrial hexactins may also be spherical but often they are elongate, often with irregular shaft having a widening some distance from the base. Pinular ray of atrial hexacins is 0.074– 0.463 mm in diameter (n=30, avg: 0.226 mm, std: 0.135 mm), tangential rays are 0.078–0.152 mm in diameter (n=30, avg: 0.114 mm, std: 0.018 mm), the ray directed inside the body is 0.078–0.152 mm in diameter (n=30, avg: 0.105 mm, std: 0.014 mm), the diameter of pinular ray is 0.019–0.026 mm at base and 0.022–0.052 mm in maximal mediate part, the diameter of other rays is about 0.015 mm at base. MICROSCLERES. Most microscleres are thickrayed discohexactins, but there are rare discohemihexasters and sometimes discohexasters with 2–4 secondary rays. Lophodiscohexasters with 4–12 secondary rays are common close to the dermal and atrial surfaces. Some of these spicules have stout shafts, some have some secondary rays raised from the side of the primary rays, rarely lophodiscostauis 0.02–0.10 mm. Specific types of large hexactins are located beneath the atrial surface, each having a shortened ray directed outside the body with rough or short spiny rounded distal ends. Sometimes this ray is lanceolate in shape, and they do not protrude over the entire atrial surface. This outwardly protruding ray is about 0.6 mm long, whereas tangential rays are 1,3 mm long. The ray directed inside the body is about 0.8 mm long and the diameter of these rays is 0.04–0.05 mm. The diactins of the peduncle have a diameter of 0.015–0.053 mm and are connected to each other by numerous synapticular junctions. Dermalia and atrialia are pinular hexactins, they have rounded or conically pointed outer ends, tangential rays and the ray directed inside the body are short-spiny. Some rare dermal pentactins have no pinular ray; the unpaired ray is equal in shape to other rays. Pinular ray of dermal hexacins is spherical, 0.067–0.107 mm in diameter (n=25, avg: 0.085 mm, std: 0.011 mm), tangential rays are 0.074–0.141 mm in diameter (n=25, avg: 0.104 mm, std: 0.016 mm), the ray directed inside the body is 0.056–0.111 mm in diameter (n=25, avg: 0.089 mm, std: 0.015 79Rossellidae from the Bering Sea Fig. 20. Spicules of Caulophacus (Caulophacus) miri sp.n., holotype. A — thick choanosomal diactin. B– D — choanosomal diactins. E — choanosomal hexactin. F — hypodermal or hypoatrial pentactin. G — hypoatrial hexactin. H — dermal pinular hexatin. I — dermal hexactin. J–M — atrial pinular hexactins. N– O — discohexasters. P — abnormal discohexaster. Q–R — discohemihexasters. S — abnormal discohexaster. T–V — lophodiscohexasters. W — lophodiscostauraster. X — abnormal stauractin. Рис. 20. Спикулы Caulophacus (Caulophacus) miri sp.n., голотип. A — толстая хоаносомальная диактина. B–D — хоаносомальные диактины. E — хоаносомальная гексактина. F — гиподермальная или гипоатриальная пентактина. G — гипоатриальная гексактина. H — дермальная пинулярная гексактина. I — дермальная гексактина. J–M — атриальные пинулярные гексактины. N–O — дискогексастры. P — аномальный дискогексастр. Q–R — дискогемигексастры. S — аномальный дискогексастр. T–V — лофодискогексастры. W — лофодискостаурастер. X — аномальная стаурактина. with the diameter of their primary rosette being 0.023–0.063 mm (n=25, avg: 0.037 mm, std: 0.010 mm). REMARKS. In comparison to other species in this subgenus, the new species has a notable and significant difference in the sizes between dermal and atrial spicules. This feature is observed also in the type species — Caulophacus (Caulophacus) rasters are found. The diameter of discohexactin is 0.089–0.185 mm (n=27, avg: 0.135 mm, std: 0.032 mm). The thick–rayed discohexasters are 0.059– 0.104 mm in diameter (n=9, avg: 0.078 mm, std: 0.013 mm), the diameter of the primary rosette is 0.036–0.044 mm (n=9, avg: 0.039 mm, std: 0.003 mm). The lophodiscohexasters are 0.036–0.101 mm in diameter (n=25, avg: 0.067 mm, std: 0.016 mm), 80 K.R. Tabachnick et al. latus Schulze, 1886 (re-described later: Schulze, 1887; Tabachnick, 2002b). Unlike it, the new species has dermal hexactins with spherical shape of pinular heads; atrial hexactins with widened pinular rays and often they have irregular overall shape of the pinular ray when it is thickest at base, close to the center of the spicule. Microscleres sizes are also quite different between these species. Caulophacus (Caulophacus) latus has calycocomes or lophodiscohexasters which are extremely large. Other species of Caulophacus (Caulophacus) which also have larger pinular ray in atrial hexactins and pentactins carry short spines on this ray. ETYMOLOGY. The species is named after the HOV ‘Mir’ which collected this specimen. DISTRIBUTION. Currently found only off the Pacific side of Bering Island, at 5952 m depth. Caulophacus (Caulophacus) subarcticus sp.n. Figs 21, 22; Suppl. Tab. 13. MATERIAL. HOLOTYPE: IORAS 5/2/2274: RV ‘Akademik Mstislav Keldysh’ – 22, sta. 2306, trawl, Pacific sine of the Bering Island, 54°57.1– 57.7′ N 165°49.9–51.0′ E, 4401–3797 m. DESCRIPTION. BODY. The specimen is fungus–like with a discoidal body 25 mm in diameter and 1–2 mm in thickness. The peduncle is about 1.5 mm in diameter and 35 mm long. SPICULES. MEGASCLERES. Choanosomal spicules are diactins and hexactins. The diactins are divided into two types: large and small. The former (about 1.5/0.02 mm) have stout shafts, conically pointed outer ends. Common diactins are thin with a widening in the middle, the outer ends are rough, rounded or clavate, these diactins are 0.9–2.4/0.006– 0.009 mm. Choanosomal hexactins have conically pointed outer ends, their rays are 0.6–0.8/0.02–0.04 mm. Hypodermal and hypoatrial pentactins have smooth tangential rays or they are spiny at base, the ray directed inside the body may be spiny, the outer ends are smooth, conically pointed. The tangential rays of hypodermal and hypoatrial pentactins are 0.3–0.5 mm long, the ray directed inside the body is 0.6–1.0 mm, the diameter of these rays is 0.02–0.03 mm. Spicules of the peduncle are diactins about 8/ 0.006–0.023 mm with stout shafts, rounded or clavate outer ends. Unlike the penduncular diactins of other species, these do not fuse to each other. Dermalia are hexactins as well as rare pentactins with a rudimental tubercle instead of a sixth ray directed inside the body. Dermal hexactins include those with clavate pinular rays and long tangential rays as well as those with a lanceolate pinular ray. The tangential rays and the ray directed inside the body are rough or short-spiny at their distal half with conically pointed outer ends. The clavate pinular ray of dermal hexactin is 0.037–0.141 mm long (n=25, avg: 0.079 mm, std: 0.023 mm), maximal diameter of this ray is 0.011 mm, tangential rays are 0.041–0.107 mm long (n=25, avg: 0.087 mm, std: 0.015 mm), the ray directed inside the body is 0.030–0.093 mm long (n=25, avg: 0.066 mm, std: 0.018 mm), the diameter of these rays is 0.006 mm. Lanceolate pinular ray of dermal hexactin is 0.070–0.159 mm long (n=25, avg: 0.123 mm, std: 0.020 mm), the maximal diameter of this ray is 0.004 mm, tangential rays of these spicules are 0.052–0.081 mm long (n=25, avg: 0.064 mm, std: 0.010 mm), the ray directed inside the body is 0.033–0.078 mm long (n=25, avg: 0.059 mm, std: 0.011 mm), the diameter of these rays is about 0.003 mm. Atrialia are pentactins with rudimental tuberculated ray directed inside the body or sometimes hexactins, these spicules have pinular ray elongate Fig. 21. Caulophacus (Caulophacus) subarcticus sp.n., holotype, external shape. Scale 10 mm. Рис. 21. Caulophacus (Caulophacus) subarcticus sp.n., голотип, внешний вид. Масштаб 10 мм. 81Rossellidae from the Bering Sea Fig. 22. Spicules of Caulophacus (Caulophacus) subarcticus sp.n., holotype. A–B — dermal pinular hexactins. C — dermal pinular pentactin. D–E — atrial pinular pentactins. F — hypodermal or hypoatrial pentactin. G — choanosomal hexactin. H–I — choanosomal diactins. J — thick-rayed discohexactin. K — thin–rayed discohexactin. L — discohexaster. M — intermedium spicule between discohexaster and lophodiscohexaster. N — lophodiscohexaster. Рис. 22. Спикулы Caulophacus (Caulophacus) subarcticus sp.n., голотип. A–B — дермальные пинулярные гексактины. C — дермальная пинулярная пентактина. D–E — атриальные пинулярные пентактины. 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