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A single specimen of feather star Comaster nobilis (Carpenter, 1884) was collected from the shallow waters of Sagami Bay, Kanagawa Prefecture, Japan in December 2022. This specimen is the new distributional record of C. nobilis from Sagami Bay and the northernmost finding in Japanese waters. We described the external features of this feather star species that is rarely encountered in middle latitudinal warm waters in Japan. [ABSTRACT FROM AUTHOR]

A single specimen of a basket star Astroglymma sculptum (Döderlein, 1896) was collected from the shallow water of Sagami Bay, Kanagawa Prefecture, Japan in June 2022. This specimen is the northernmost record of A. sculptum which so far has been known from the tropical and subtropical waters south of the Kii Peninsula, Wakayama Prefecture, Japan. We described the new locality and external features of this basket star that is rarely encountered species in middle latitudinal warmwater settings in Japan. New Japanese genus name, “Aka-tezurumozuru-zoku” was provided for the Astroglymma. [ABSTRACT FROM AUTHOR]

Gastropods of the genus Mucronalia (Eulimidae) are known ectoparasites of brittle stars (Ophiuroidea). However, the identities of host species are only known for three of some ten described species in the genus. Here, we report associations of Mucronalia snails, including one new species, with ophiuroid hosts from Japan and New Caledonia: M. spp. aff. alba with Ophiomastix annulosa, Ophiomastix mixta, and Ophiocoma cynthiae; M. sp. cf. exquisita with Amphioplus (Amphioplus) sp.; Mucronalia ryukyuensis n. sp. with Ophionereis porrecta; and Mucronalia sp. with Amphiura velox. Mucronalia ryukyuensis n. sp. is described from Okinawa, southwestern Japan. The new species is characterized by its slender shell with a large body whorl and aperture compared with other species of the genus. Among Japanese congeners, the shell of the new species is most similar to that of M. exilis, but differs in having a teleoconch with less-convex whorls, regularly increasing in diameter. The present study corroborates Warén's (1983) general rule that eulimids in a single genus parasitize hosts of the same echinoderm class, and our records suggest that closely related species of Mucronalia tend to exploit hosts of a more restricted lineage. We also briefly discuss the divergence processes of Mucronalia snails, which likely involve host shifts and geographic isolation. [ABSTRACT FROM AUTHOR]

Echinoderms, including sea urchins and starfish, have played important roles in cell, developmental and evolutionary biology research for more than a century. However, since most of them take a long time to mature sexually and their breeding seasons are limited, it has been difficult to obtain subsequent generations in the laboratory, resulting in them not being recognized as model organisms in recent genetics research. To overcome this issue, we maintained and obtained gametes from several nonmodel sea urchins in Japan and finally identified Temnopleurus reevesii as a suitable model for sea urchin genetics. Genomic and transcriptomic information was obtained for this model, and the DNA database TrBase was made publicly available. In this review, we describe how we found this species useful for biological research and show an example of CRISPR/Cas9 based knockout sea urchin. [ABSTRACT FROM AUTHOR]

We described the external features of an echinoid, Caenopedina pulchella (A. Agassiz & H. L. Clark, 1907), a rarely encountered species as well as the first record from Japanese waters. The morphological characteristics of three specimens collected off Nagasaki in the East China Sea (depth 384-378 m) in 2012, off Misaki in Sagami Bay (depth 94-100 m) in 2014, and off Toshima in the Izu Islands (depth 370 m) in 2015 were consistent with the previous descriptions. These findings expand the northernmost range of this species in the North Pacific. We proposed a new Japanese standard name, Myoga-gaze, for this species. [ABSTRACT FROM AUTHOR]

Ten excellent specimens of Chondrometra rugosa A. H. Clark 1918 (Echinodermata, Crinoidea, Comatulida, Charitometridae) were collected from the depth of 763-796 m off the Shima Peninsula, Kumano-nada Sea, central Japan on May 1st, 2004. This species has been known from tropical West Pacific. This is the first record for waters around Japan. We propose the Japanese name of this species as "Oni-katsura-umishida". [ABSTRACT FROM AUTHOR]

The starfish Asterias amurensis is a marine pest native to the northwestern Pacific and has successfully invaded southern Australia. Asterias amurensis have caused substantial environmental and economic impacts in both native and non-native regions. However, little information is available about the genetic features of its native populations, especially for those in North China. Here we sequenced the complete mitochondrial genomes of five individuals from different locations in China and compared their characteristics with three mitogenomes available from Japan. Multiple analyses and comparisons revealed little difference in the gene composition, gene order, codon usage, and nucleotide content among the eight mitogenomes. However, intraspecific phylogenetic reconstruction unveiled two divergent lineages between specimens from North China plus Ushimado (Seto Inland Sea, Japan) and northern Japan (Asamushi and Onagawa). This conclusion was backed by an analysis of pairwise genetic distances, which showed that individuals from different lineages had relatively higher values (all above 2%). Based on knowledge of paleoenvironmental and tectonic activity in the northwestern Pacific, the two lineages might have originated during the Early Pliocene due to the isolation of the East China Sea from the Japan Sea/East Sea during that time, while the present-day distribution of these lineages have likely been influenced by the ocean current system. [ABSTRACT FROM AUTHOR]

More than 100 individuals of sea cucumber larvae were collected in the Japanese coastal sea of Moroiso, Sagami Bay, Kanagawa Prefecture, central-eastern Japan, in January 2018. Based on an obtained sequence of mitochondrial 16S rRNA gene region of one juvenile, it was identified as Sclerodactyla multipes by BLAST search with 0.3% genetic distance. The developmental process of the S. multipes was observed for three months, in which time, they grew from 250 μm to about 4 mm in length; here they showed distinct tentacles and dermal ossicles. Detailed morphological features of this species were described based on stereomicroscopic, fluorescence and SEM observations for the first time. This is the first description of life history through planktonic larva to juveniles in the family Sclerodactylidae. [ABSTRACT FROM AUTHOR]

An ascothoracidan crustacean of the genus Dendrogaster Knipowitsch, 1890 (Dendrogasteridae), known for more than 80 years to infect the sea star Certonardoa semiregularis (Müller & Troschel, 1842) and previously identified as Dendrogaster ludwigi Le Roi, 1905 , is described as a new species on the basis of recently collected specimens from Mie and Yamaguchi Prefectures, Japan. Dendrogaster adhaerens n. sp. was found within the coelomic cavity of the arms of its host sea star. Partial sequences of the cytochrome c oxidase subunit I (COI) gene show that the specimens from both localities are conspecific. This new species was also confirmed to be morphologically distinct from Dendrogaster sp. cf. ludwigi infecting Echinaster luzonicus (Gray, 1842), which has also been confused with D. ludwigi. The new species differs from all of its congeners in the anastomosis of the posterior primary branches and its adhesion to the inner body wall of the host. [ABSTRACT FROM AUTHOR]

A new parasitic species of eulimid gastropod, Haliella seisuimaruae sp. nov., is described from bathyal (728-978 m) waters off the Pacific coasts of Japan. It shows the closest resemblance to the type species H. stenostoma from the North Atlantic and Barents Sea in having a tall shell with an almost straight outer lip, but differs in having a junction of the parietal wall and columellar lip at 38% of the aperture height from the suture (33% in H. stenostoma), a slightly wider aperture and a more curved and extended columellar lip. The holotype of H. seisuimaruae sp. nov. was found attached to an irregular sea urchin, Brissopsis sp. cf. luzonica (Spatangoida: Brissidae). This represents the first direct observation of parasitic ecology and echinoderm host for the genus Haliella. A new replacement name, Eulima tsushimensis nom. nov., is proposed here for Eulima stenostoma A. Adams, 1861, which is preoccupied by Eulima stenostoma Jeffreys, 1858 (type of Haliella). [ABSTRACT FROM AUTHOR]

Two new species and two new occurrence records of the genus Ophiambix Lyman, 1880 (Echinodermata: Ophiuroidea), were found on hydrothermal vents at the Pacific coast of Japan. Ophiambix kagutsuchi, new species, is distinguished from other congeners in having small granules separated from each other on aboral surface of disc, flat teeth, second from oral-most arm spines being cylindrical and spiniform in shape, and one small and spiniform tentacle scale on each tentacle pore. Ophiambix macrodonta, new species, is distinguished from the other congeners in having small granules circularly arranged surrounding the periphery of disc scales on aboral surface of disc, flat teeth, second from oral-most arm spines being flat and leaf-like in shape, and one small and spiniform tentacle scale on each tentacle pore. Furthermore, Ophiambix epicopus Paterson & Baker, 1988, was recorded from Japan for the first time and another congener, Ophiambix aculeatus Lyman, 1880, was also collected. Ophiambix kagutsuchi, new species, and Ophiambix macrodonta, new species, were collected from deep-sea chemosynthetic environments. A tabular key to all six species of the genus Ophiambix is provided. [ABSTRACT FROM AUTHOR]

In 2011, a tropical holothurian was found off the temperate coast of Kagoshima, Kyushu, Japan. This holothurian was identified as Stichopus naso Semper, 1867, which was first described in the Philippines, and is known to be distributed within the tropical Indo-West Pacific region. Herein, we examined its morphological characteristics and compared it with pre-described examples and discuss its origin from the perspective of climate change and artificial transfer. We considered that both perspectives are plausible because sea water temperature has recently risen around Japan, creating the possibility of eggs and larval transfer from southern regions and the consequent establishment of adult S. naso populations. Accidental introduction via ballast water from vessels and other pathways may not be implausible. In any case, ocean warming caused by global climate change is considered as a key factor in the survival and settlement of adult S. naso populations. [ABSTRACT FROM AUTHOR]

Three new species of the ascothoracidan crustacean genus Dendrogaster Knipovich, 1890 (Dendrogasteridae) are described from goniasterid sea-stars in Japan. Dendrogaster komatsuae sp. nov. and D. tobasuii sp. nov. were found respectively in the coelomic cavities of Lithosoma japonica Hayashi, 1952 and two species of Mediaster: M. arcuatus (Sladen, 1889) and M. brachiatus Goto, 1914 from the Kumano-nada Sea. Dendrogaster nagasakimaruae sp. nov. was similarly found in Nymphaster euryplax Fisher, 1913 from the East China Sea. Partial DNA sequences of the cytochrome c oxidase subunit I and 16S ribosomal RNA genes were determined for D. tobasuii sp. nov. These findings represent the first records of Dendrogaster from the host family Goniasteridae in Japan. [ABSTRACT FROM AUTHOR]

The subgenus Setihenricia Chichvarkhin and Chichvarkhina, 2017 currently consists of 32 out of 94 species of sea stars in the genus Henricia Gray, 1840. However, only 10 have been molecularly ascertained as to the phylogenetic position. Based on seven mitochondrial gene markers (16S rRNA, COI, tRNA-Ala, tRNA-Leu, tRNA-Asn, tRNA-Gln, and tRNA-Pro), we performed molecular analyses to assess the monophyly of Setihenricia using 16 species of Henricia from Japanese waters, as well as other congeners for which sequences were available in public databases. The monophyletic Setihenricia was only weakly recovered because the support values were low, but we assume this taxon may be valid in consideration of a morphological key. Henricia kinkasana Hayashi, 1940 is herein identified as a new member of Setihenricia, based on molecular and morphological evidence. Sequences in the public databases previously identified as H. compacta (Sladen, 1889) and H. obesa (Sladen, 1889) were nested in the Setihenricia clade; these two species are also likely members of Setihenricia . Our morphological assessment yielded three findings: (1) the number of the rows of spines on each inferomarginal plate, being three or more, appears to be a useful diagnostic character for Setihenricia, as has been suggested in previous studies, (2) the degree of spine tapering turned out to be less relevant in diagnosing the subgenus than previously supposed, (3) two newly introduced characters--( i ) the width of adambulacral plates and ( ii ) the ratio of two measurements in ambulacral plates to the length of interradius--may be effective to distinguish members of this apparent Henricia subclade from other members of the genus. [ABSTRACT FROM AUTHOR]

We report seven species of the genus Henricia Gray, 1840 that were found in Vostok Bay, and two species from adjacent area, known from museum collection or seen in underwater footage. while existing literature reported no confirmed species from this area. Most of these species: H. djakonovi, H. alexeyi, H. densispina, H. hayashii, H. granulifera, H. pacifica, H. asiatica, and H. oculata robusta were reported from the Sea of Japan previously. H. nipponica, known from Japan, is reported from Russian seas for the first time. All studied taxa are re-described here using a range of morphological characters and partial 16S rRNA nucleotide sequences, life colorations of several species are reported for the first time, and an identification key is provided. Lectotype designations are fixed for studied series of species described by AM Djakonov. [ABSTRACT FROM AUTHOR]

Metacrimenes fenestra, a new palaemonid genus and species is described on the basis of an ovigerous female and one juvenile specimen from Suruga Bay, central Japan. The specimens were associated with the stalked crinoid Metacrinus rotundus Carpenter, 1885, collected at a depth of 131200 m. Photographs taken in situ indicate that the shrimp lives ectosymbiotically on its crinoid host. The greatly reduced bud-like exopod on the third maxilliped links the new genus to Mesopontonia Bruce, 1967 (Indo-West Pacific) and Waldola Holthuis, 1951 (East Pacific), in which the exopod is absent, but the presence of antennal spine on the carapace and the non-elongate, symmetrical second pereopods immediately distinguish Metacrimenes n. gen. from these genera. Molecular phylogenetic analysis using a dataset concatenating two mitochondrial markers (16S rRNA and COI genes) clusters the new genus with Paraclimenes gorgonicola (Bruce, 1967), two species of Mesopontonia and Brucecaris tenuis (Bruce, 1969). However, in Paraclimenes Bruce, 1995 and Brucecaris Marin & Chan, 2006, the third maxilliped exopod is normally developed, flagellum-like. Other differentiating characters between the new taxon and the presumably allied taxa are discussed.

A new dendrochirotid sea cucumber collected in the intertidal zone of western Japan, Lipotrapeza littoralis sp. nov., is described. This species has a medium body size (approximately 30-80 mm), brownish body color, 20 tentacles arranged in a double circle (15+5), a long calcareous ring, ten anal papillae and five anal scales, and numerous pedicels covering the entire body at an even density. For comparison, we also examined the syntype specimens of Lipotrapeza japonica Heding and Panning, 1954 and provide illustrations of the general appearance of its body, calcareous ring, and ossicles. The calcareous rings of both species are very similar in appearance, but the new species is readily distinguishable from L. japonica by the number of anal papillae. The appearance of the rosette ossicles also differs in the two species. [ABSTRACT FROM AUTHOR]

Gastropods of over a dozen genera in the family Eulimidae have been identified as parasites of brittle stars, and many more remain to be discovered and described for a comprehensive understanding of the evolutionary history of their host-parasite relationships. In this study, we describe Fusceulimoides kohtsukai gen. et sp. nov., parasitic on the little brittle star, Ophiactis savignyi (Ophiactidae), in Kanagawa, central Japan. The new genus is distinguished from other eulimid genera by the combination of following seven conchological characters: (1) a very small size of up to 1.7 mm high, (2) a colorless translucent appearance, (3) a conical pupiform shape with a paucispiral protoconch, (4) slightly convex teleoconch whorls, (5) a remarkably large body whorl occupying 65-70% of the total shell height, (6) a broad, somewhat squarish and laterally expanded aperture with a strongly curved outer lip, and (7) a developed parietal callus without an indentation or depression in the umbilical area. A multi-locus molecular phylogeny revealed its distant relationship to Hemiliostraca + Pyramidelloides , a previously known clade of ophiuroid parasites, thereby suggesting multiple origins of this host-parasite association in Eulimidae.

Well preserved, articulated brittle star skeletons from the early Carnian (early Late Triassic)HalobiaShales of Yamaguchi, Japan, are described as a new genus and species of the family Ophiacanthidae:Leadagmara gracilispina. The new form constitutes the oldest unequivocal representative of this extant ophiuroid family, significantly extending its stratigraphical range. The first cladistic analysis of the Ophiacanthidae including all extant genera suggestsL. gracilispinaholds a basal, but not the basalmost, position within the family, forming a sister group with the extantOphiomedeaandOphioprististo the other ophiacanthids except forOphiologimus, which itself is sister to all other ophiacanthids. These results imply that ophiacanthids originated in the pre-Carnian. A critical re-evaluation of the ophiacanthid fossil record reveals that the vast majority of records consist of dissociated lateral arm plates, which provide no insights into divergence times of the lineages. Among the few records of articulated specimens, onlyInexpectacantha acrobaticafrom the Pliensbachian of France proved sufficiently well-known to yield phylogenetically relevant information. Its position within the ophiacanthid clade indicates that more than half of the extant ophiacanthid lineages, in particular the former ophiacanthinids and ophiotominids, must have diverged by the Pliensbachian. http://zoobank.org/urn:lsid:zoobank.org:pub:F64E44C3-7275-4EC8-B048-4C7B2C6D57EF [ABSTRACT FROM AUTHOR]

A new dendrochirotid sea cucumber, Satsumaocnus kaiyomarui gen. nov., sp. nov. from deep water of southern Japan is herein described. The new species displays the following unique characters : a cylindrical, soft body; mouth surrounded by five oral valves; 10 equal, dendritic tentacles arranged in a single circle, each composed of two tufts; a low, stout, compact, calcareous ring without posterior prolongations; body wall ossicles comprising an external layer of small, x-framed hourglass-shaped cups originally described as "double-faced x-framed cup ossicles" in a previous study reported by Yamana et al. (2019), and an inner layer of scarce dendriform/branched rods, sometimes taking the shape of delicate plate-like deposits. Although the general (external and internal) morphological characters of the new species correspond well with the characters of species within the cucumariid subfamily Colochirinae Panning, 1949, our material lacks any buttons or elaborate plate-like ossicles which characterize all extant genera within this subfamily. We, therefore, describe our material as a new species S. kaiyomarui sp. nov. within the new genus Satsumaocnus. The predominant body wall deposits of the new species strongly resemble the hourglass type ossicles of some species of the psolid genus Lissothuria (Verrill, 1867), but differ in their possession of a supporting x-shaped frame. In addition, it is noteworthy that these hourglass deposits also resemble the table ossicles of some holothuriids and stichopodids, when viewed from the side, especially the small tables of some Labidodemas and/or Stichopus species, while the dendriform rods resemble those of Thelenota.

Reproduction and larval/post-larval development of the one of the smallest known comatulid Dorometra sesokonis were studied on the coral reefs of Sesoko-jima Island, Okinawa, Japan. Breeding individuals were found every month from May 2003 to April 2004 indicating continuous reproduction. Individuals possessed both mature ovaries and testes, and were therefore characterized as simultaneous hermaphrodites. This species was observed to be an external brooder in which the embryos developed on the surface of parental genital pinnules until the doliolaria larval stage, and subsequently released doliolariae settled on substrata within 4 days after hatching. Larvae then metamorphosed into the post-larval cystidean stage, which lasted for more than a month. The reproductive features of this species are unique among crinoids, and, together with juvenile morphological features observed in adults, can be interpreted as adaptations to their cryptic habitat, which is subject to frequent natural disturbances. [ABSTRACT FROM AUTHOR]

Marine stations have continued to contribute significantly to understanding the physiology, taxonomy, development, ecology, and evolution of animals. There are more than 50 marine stations of national universities in Japan, and historically their establishments were closely related to the initial stage of zoology in the country. More than 10 years ago, Japanese Association for Marine Biology (JAMBIO) was established to facilitate the collaboration among marine stations in the activities of research, education and administration. One of the successful activities of JAMBIO that contribute to zoology is the JAMBIO Coastal Organism Joint Surveys, in which scientists and students at multiple marine stations, as well as those from research institutes or museums, stay at a marine station for a few days, and collect and make a record of marine organisms. As of 2021, 22 surveys have been performed and new species have been reported from taxa such as Cnidaria, Nematoda, Platyhelminthes, Annelida, Mollusca, Arthropoda, and Echinodermata.

Ctenostome bryozoans were collected from depths of 150-300 m in Suruga Bay, the Kumano Sea, and off Sendai Bay on the Pacific coast of Japan. Among these samples were five new species, three of which were epibiotic on other animals. Alcyonidium clavum n. sp., found encrusting cirri of the stalked crinoid Metacrinus rotundus , was previously reported in Japan as Alcyonidium mamillatum , but differs from the latter in lacking rings on the peristome. Triticella parvacrista n. sp. and Triticella cunabula n. sp. were epibiotic on the isopod Bathynomus doederleini and the pycnogonid Ascorhynchus japonicum , respectively. This is the first record of the genus Triticella from Japanese waters. These species differ from previously described species in autozooidal morphology, particularly the dimensions of the autozooidal dilatation, in the presence or absence of the frenaculum, and in the septate junction between the dilatation and pedicel. Bockiella arcatumida n. sp., found as erect colonies on pebbles and hydroids collected off Sendai Bay, differs from previously known species in the size and arrangement of the kenozoids in the branch. Metalcyonidium morum n. sp., collected southwest of the Izu Peninsula, occurred as small colonies having a peduncle of short kenozooids. This is the first record from the northwestern Pacific for both the genus Metalcyonidium and the family Clavoporidae. Metalcyonidium morum n. sp differs from Metalcyonidium gautieri , the only other species known in the genus, in having the capitulum divided into two parts, and in the length of the kenozooids comprising the peduncle.

The northern Pacific seastar Asterias amurensis Lütken was recently introduced to Tasmanian waters, possibly through ballast water discharged from ocean-going vessels. Three Tasmanian populations and seven native populations from Japan and eastern Russia were examined in 1994 for variation at 22 allozyme loci. There was significant spatial heterogeneity in gene frequencies among the native populations, especially for the ocus APK, where Gwas a very high 0.47. The Tasmanian populations could not be separated genetically from one another, suggesting they have a common origin from a single introduction. The average heterozygosity per locus of the Tasmanian populations (0.116 to 0.127, mean 0.123) was ∼30 to 40% less than that of the native populations (0.177 to 0.216, mean 0.192), suggesting that colonisation of Tasmanian waters was accompanied by a population-size bottle-neck. The Tasmanian seastars were genetically more closely related to the two populations from central Japan (Suruga and Tokyo Bays) than to populations from Vladivostok, northern Japan (Yoichi, Nemuro and Mutsu Bays) or southern Japan (Ariake Sea). However, there were significant differences between the populations from Tasmania and central Japan, which may be attributable to founder effects or may mean that the true source of the Tasmanian introduction has yet to be identified. [ABSTRACT FROM AUTHOR]

Two new water-soluble phenanthroperylene quinones, gymnochrome H ( 2 ) and monosulfated gymnochrome A ( 3 ), as well as the known compounds gymnochrome A ( 4 ) and monosulfated gymnochrome D ( 5 ) were isolated from the deep-sea crinoid Hypalocrinus naresianus , which had been collected in the deep sea of Japan. The structures of the compounds were elucidated by spectroscopic analysis including HRMS, 1D 1 H and 13 C NMR, and 2D NMR. The absolute configuration was determined by ECD spectroscopy, analysis of J -couplings and ROE contacts, and DFT calculations. The configuration of the axial chirality of all isolated phenanthroperylene quinones ( 2 - 5 ) was determined to be ( P ). For gymnochrome H ( 2 ) and monosulfated gymnochrome A ( 3 ), a (2' S ,2″ R ) configuration was determined, whereas for monosulfated gymnochrome D ( 5 ) a (2' R ,2″ R ), configuration was determined. Acetylated quinones are unusual among natural products from an echinoderm and gymnochrome H ( 2 ) together with the recently reported gymnochrome G ( 1 ) represent the first isolated acetylated phenanthroperylene quinones.

The ophiuroid species listed were collected by benthic faunal surveys from 2016 to 2018 in submarine caves of the Ryukyu Islands, southwestern Japan. The material includes 20 species from 8 families, Amphiuridae, Ophiocomidae, Ophiodermatidae, Ophiolepididae, Ophioleucidae, Ophiomyxidae, Ophionereididae and Ophiotrichidae. This is the first comprehensive report of submarine cave-dwelling ophiuroids from Japanese waters. Also provided is a redescription of a rare species, Dougaloplus echinatus (Ljungman, 1867), with a detailed description of its ossicle morphology. The species has previously been reported from Brazil, Australia, Eastern Indian Ocean to Southern China, in 11-118 m depth, and this is the first record of D. echinatus from Japanese waters. A brief discussion of the scarcity of submarine cave systems, and the need for their conservation, is provided.

Four new dendrochirotid sea cucumbers, Neocucumis misakiensis sp. nov., Pseudocolochirus misakiensis sp. nov., Lipotrapeza purpurata sp. nov., and Pentamera misakiensis sp. nov., and three other known species, Amphicyclus japonicus Bell, 1884, Cucumaria tegulata Augustin, 1908, and Placothuria ohshimai Liao, 1997, are described from off Jyogashima Island, Misaki peninsula, south coast of Kanagawa Prefecture, Japan. In this study, Cucumaria tegulata Augustin, 1908, is referred to the genus Hemiocnus Mjobo Thandar, 2016. Furthermore, a new phyllophorid genus Pseudoplacothuria is here erected to accommodate Placothuria ohshimai Liao, 1997. Although its external and internal body morphology and most of the ossicle morphology resemble those of Pentamera spp., it differs in possessing thick lens-shaped ossicles in the body wall, and also in possessing needle-shaped ossicles in the gonadal tubules.

A revision of the genus Astrodendrum Döderlein (Ophiuroidea, Euryalida, Gorgonocephalidae) is based on 14 specimens, including the holotypes of Astrodendrum galapagense A. H. Clark and Astroconus capense Mortensen and a syntype of Gorgonocephalus sagaminus Döderlein. A new species Astrodendrum spinulosum is described from the Pacific coast of Japan. It is distinguished from its congeners in having conical external ossicles on aboral side of the disc; bulges on lateral edges of proximal arms; 1 terminal projection on each arm spine of proximal portion of the arm; 2 or 3 secondary teeth on each hook-shaped arm spine of distal portion of the arm. A taxonomic key to all six species of the genus Astrodendrum is provided.

The specimens of Paralepas maculata on a sea urchin, Prionocidaris sp. were collected in Okinawa, southern Japan. This species has not been reported since its original description. This represents the first observation of this species from Okinawa and the first instance found on this sea urchin species. In this paper, the morphology of the new P. maculata specimens is reported, and compared with the type series of this species. Small individuals were found on the holotype. The probable androdioecious sexual system of the species, which includes dwarf-male like individuals and hermaphrodites, is discussed. This study was facilitated by the collaboration of scientists and aquarium staff, suggesting the potential of such collaborations in biodiversity studies. [ABSTRACT FROM PUBLISHER]