A single pelagic juvenile (23.1 mm standard length) of a lophiid fish, collected from 100–115 m in depth in the East China Sea, was identified as Sladenia zhui Ni, Wu, and Li, 2002, originally described from the East and South China Seas, on the basis of meristic counts [I-I-I-I, 10 dorsal-fin rays (2 post-cephalic spines); 7 anal-fin rays; and 19 pectoral-fin rays] and mitochondrial DNA sequences. Reported here for the first time, juveniles of Sladenia Regan, 1908 are uniquely characterized by inflated, balloon-like skin surrounding the head and body, and undeveloped head spines. The Japanese names “Daruma-ankou-zoku” and “Daruma-ankou” are proposed herein for the genus Sladenia and S. zhui, respectively.

A new nematode species that is lung parasitic to a bufonid toad, Rhabdias kafunata sp. nov., is described and illustrated from Miyakojima island, Okinawa Prefecture, Japan. Although the new species was previously identified as R. incerta Wilkie, 1930, it is clearly distinguishable from that species by the characteristics of body proportion, buccal capsule, and esophagus. Additionally, the new species differs from other congeners inhabiting East Asia and the Russian Far East in the following features: longer body length, cup-like buccal capsule, longer esophagus length, presence of thickened anterior muscular part in esophagus, cuticular inflation less prominent in region posterior to small cephalic cuticular inflation, middle part of body and tail tip, and tail long and tapering. Partial sequences of mitochondrial cytochrome c oxidase subunit I and 12S rDNA genes were provided as DNA barcodes for the new species.

A single specimen of Thrissina dussumieri (Valenciennes, 1848) collected from the Ogasawara Islands, previously reported and briefly described ca. 90 years ago, has since been largely overlooked in studies of Japanese engraulid fishes. The specimen was re-examined and described in detail, and the record of T. dussumieri from Japanese waters is confirmed. The new standard Japanese name “Tsurugi-katakuchi” is proposed.

During the past three decades, ten specimens (174.1–235.1 mm standard length) of the Bluespotted Hind Cephalopholis cyanostigma (Valenciennes in Cuvier and Valenciennes, 1828), distributed in the eastern Indian and western Pacific oceans, have been collected from the southern Ryukyu Islands, Japan, although the species has been formally recorded from Japanese waters only on the basis of a single photograph, with the northernmost specimen-based record being Taiwan. The Ryukyu Island specimens, described here in detail, represent the first specimen-based records of C. cyanostigma from Japan, in addition to the northernmost record of the species. The new standard Japanese name “Samidare-hata” is proposed for the species.

Canthidermis macrolepis (Boulenger, 1888) is newly recorded from Japan and Micronesia on the basis of nine specimens (206.9–349.8 mm SL), having been previously reported from the northwestern Indian Ocean and northern South China Sea (the latter based solely on DNA barcoding). The species is probably widespread throughout the Indo-West Pacific region but has been confused with Canthidermis maculata (Bloch, 1786). Detailed morphological comparisons of both species resulted in the following differences being recognized between them: numbers of body scale rows [38–41 (modally 40) in C. macrolepis vs. 40–49 (44) in C. maculata], second dorsal-fin rays [25–27 (26) vs. 22–26 (24)], anal-fin rays [22–24 (23) vs. 20–23 (21)] and pectoral-fin rays [14–16 (15) vs. 13–15 (14)]. Sequences of the mitochondrial DNA COI gene determined from the presently-reported specimens of C. macrolepis, which also differed in color from similarly sized C. maculata, having a uniformly grayish body without spots, were also compared with congeners. The Japanese standard name “Bouzu-mongara” is newly proposed for C. macrolepis.

A new spider species, Cybaeus daimonji, from Kyoto, western-central Honshu, Japan is described based on both sexes. The shape of epigyne indicates that this new species is close to C. communis Yaginuma, 1972, C. kirigaminensis Komatsu, 1963, C. maculosus Yaginuma, 1972 and C. shinkaii (Komatsu, 1970), which are distributed in eastern to central Honshu. Nuclear internal transcribed spacer 1, 28S ribosomal RNA and histone H3 as well as mitochondrial cytochrome c oxidase subunit I, 12S ribosomal RNA and 16S ribosomal RNA sequences of the new species are provided for future phylogenetic studies.

A new species of holothurian, Elpidia soyoae sp. nov., is described from the Japan Trench area, at depths of 3570–4145 m. It is distinguished from its congeners in having: four or five paired papillae and unpaired papillae present along entire dorsal radii (four to seven papillae on each radius), with wide separation between second and third paired papillae; maximum length of Elpidia-type ossicles in dorsal body wall exceeds 1000 µm; axis diameter of dorsal Elpidia-type ossicles less than 40 µm; tentacle Elpidia-type ossicles with arched axis and shortened, occasionally completely reduced arms and apophyses. Purple pigmentation spots composed of small purple particles on both dorsal and ventral body wall. This is the second species of Elpidia Théel, 1876 from Japanese abyssal depths. The diagnosis of the genus Elpidia is modified to distinguish from all other elpidiid genera. A morphological comparison of the species of the slender axis group of genus Elpidia, and partial mitochondrial cytochrome c oxidase subunit I (COI) gene sequences of type specimens are provided.

Five specimens (41.2–47.0 mm standard length) of the Indo-Pacific species Bulbonaricus davaoensis (Herald, 1953), previously recorded from Kenya, Taiwan, the Philippines, Indonesia, Papua New Guinea, Australia, and Fiji, were collected from Okinoerabu Island, Amami Islands, Ryukyu Islands and Chichi Island, Ogasawara Islands. The specimens represent the first Japanese and northernmost (Okinoerabu Island) records of the species. A detailed description is given for the specimens and the new standard Japanese name “Shuuyajiri-chin’yojiuo” is proposed for the species. Photographs of fresh metamorphosed adult specimens, a fresh larval specimen, and live individuals of B. davaoensis are provided.

A new nematode species, Rhabdias kiri sp. nov., which is a lung parasite in a microhylid frog Microhyla okinavensis Stejneger, 1901 from Ishigakijima island in the Yaeyama Islands of Ryukyu Archipelago, Japan is described and illustrated. This new species differs from other congeners inhabiting East Asia and the Russian Far East in its features: i.e., shorter body length, slender body shape, narrower and shallower buccal capsule, shorter head diameter and cuticular inflation less prominent in the anterior and middle parts of the body. This is the first record of a frog parasite in Rhabdias from the Yaeyama Islands. Partial sequences of mitochondrial cytochrome c oxidase subunit I and 12S rDNA genes were provided as DNA barcodes for the new species.

Four specimens from Minami-iwo-to island of Volcano Islands were identified as Uropterygius oligospondylus Chen, Randall, and Loh in Loh et al., 2008. It is the first identified record from Japan and the northernmost record of the species. Uropterygius oligospondylus can be characterized by the following characters: total vertebrae 100–103; body gray with blackish reticular pattern; jaws teeth in two or three rows; anus close to mid-body; head 13.7–16.7% TL; trunk 32.8–36.6% TL; body depth at gill opening 5.8–8.3% TL; eye diameter 3.9–5.3% of head length; snout 16.2–20.3% of head length; and presence of a distinct notch above mid-eye. A new Japanese standard name “Kobu-kikai-utsubo” is proposed for the species. The position of the fourth infraorbital pores from original description should be revised as “far behind posterior end of eye”.

The monostiliferous hoplonemertean Proamphiporus kaimeiae sp. nov. is described based on a single specimen collected from the bottom of the Northwest Pacific, 262 m deep, off Tohoku in Japan, by use of a remotely operated vehicle during a cruise organized by Tohoku Ecosystem-Associated Marine Sciences (TEAMS) research project in 2019. The position of the cerebral organs in the new species, being posterior to the proboscis insertion, is unusual for Eumonostilifera, which is one of the diagnostic traits of the so-far monospecific Proamphiporus Chernyshev and Polyakova, 2019, and Amphiporus rectangulus Strand, Herrera-Bachiller, Nygren, and Kånneby, 2014. The latter is herein transferred to Proamphiporus to yield a new combination, Proamphiporus rectangulus comb. nov., based on the reported internal morphology. Molecular phylogenetic analyses based on 16S rRNA, cytochrome c oxidase subunit I, 18S rRNA, 28S rRNA, and histone H3 genes placed P. kaimeiae in a clade comprised of Proamphiporus crandalli Chernyshev and Polyakova, 2019 and Proamphiporus rectangulus.

We describe a new species of ilyplanid polyclad, Zygantroides serpulidicola sp. nov., from Amakusa, Kumamoto, Japan. This is the third member of Zygantroides Faubel, 1983 and the first record of the genus from the Pacific Ocean. Zygantroides serpulidicola sp. nov. is characterized by i) the mouth opening near the common gonopore, ii) the sperm ducts separately entering a pear-shaped seminal vesicle, iii) an elongated Lang’s-vesicle duct, and iv) the horseshoe-shaped Lang’s vesicle located posterior to the common gonopore. We provide a partial sequence of the mitochondrial cytochrome c oxidase subunit I (COI) gene (712 bp) as a DNA barcode for the species. Our phylogenetic analyses based on concatenated sequences of the 16S, 18S, and 28S ribosomal DNA and COI indicate that Z. serpulidicola sp. nov. is nested in a clade comprised of Discocelidae and Ilyplanidae; the latter does not appear to be monophyletic.

Females of the lernaeopodid copepod Salmincola edwardsii (Olsson, 1869) were found parasitizing the gill area of southern Asian Dolly Varden, Salvelinus malma krascheninnikova Taranetz, 1933, from four rivers (Rusha River, Rausu River, Shari River, Shibetsu River) in and near the Shiretoko Peninsula, eastern Hokkaido Island, Japan. The females are briefly described as the first record of S. edwardsii from Hokkaido Island and the southernmost distribution record for the species in Asia. The branchial chamber was the most frequently used site for attachment by the females, followed by the gill filaments and the inner surface of the operculum. The overall prevalence of infection was 42.1%, and intensity ranged from 1 to 6 (mostly 1 or 2). The species was not collected from the central and western regions of Hokkaido Island, and the restriction of its distribution to eastern Hokkaido Island is discussed in terms of anadromy of the host species. The impact of global climatic warming on the Hokkaido populations of S. edwardsii is also discussed.

A new species of free-living marine nematode, Proplatycoma tsukubae sp. nov. (Enoplida: Leptosomatidae: Platycominae), is described from Japan. The specimens were obtained from sea-floor sediments collected at a depth of 117–202 m off the coast of Shimoda, Shizuoka Prefecture, Japan. Proplatycoma tsukubae sp. nov. is similar to P. africana (Gerlach, 1959) in the unilobed amphidial flaps. However, it differs from P. africana based on the much shorter amphidial flaps just reaching the anterior edge of the amphidial aperture, the accessory structure of the spicules being constricted at the middle and tapering toward both ends, the longer apophyses of the gubernaculum, and the blunt tip of the tail. The partial nucleotide sequences for the cytochrome c oxidase subunit I and the 18S rRNA regions in P. tsukubae sp. nov. are also presented for future applications in DNA barcoding or phylogenetic studies. Updated taxonomic keys to genera in the subfamily Platycominae and species in Proplatycoma are provided.

Tiny annelids identified as the marine meiobenthic polychaete Dinophilus gyrociliatus (Schmidt, 1857) have been reported not only from shallow water sediments but also artificial environments such as experimental aquaria almost all around the world; the species has thus been regarded to show a cosmopolitan distribution. However, various types of ciliary-band arrangements and genetic sequences have been reported from different populations, leading to a doubt on the species’ taxonomic identity. In this study, we present results of our SEM observation of Dinophilus sp. cf. gyrociliatus from Japan and provide mitochondrial 16S ribosomal RNA and cytochrome c oxidase subunit I gene sequences of Japanese populations as DNA barcodes for contributing to resolving the taxonomic uncertainty of “D. gyrociliatus”.

Monoporella projecta sp. nov. from the continental shelf and slope east of the Boso Peninsula, Japan adds to the bryozoan fauna along the northwestern Pacific coast, where more than 10 species of this genus have been recorded. Colonies of this species are uniserial encrusting in growth form, and autozooids are large and much inflated with a projecting orificial rim. These colony and zooidal characteristics may be related to the deep-water environment.

A new dendrochirotid sea cucumber, Massinium japonicum sp. nov., is described from areas in western Japan, including the middle of the Seto Inland Sea, west of the Sea of Japan, the shore of the Amakusa Peninsula, and the shore of the Kii Peninsula. The ossicle assemblage of the new species (M. japonicum) is similar to that of M. maculosum Samyn and Thandar, 2003, the type species of Massinium Samyn and Thandar, 2003. However, the new species is readily distinguishable from M. maculosum and its congeners by the absence of rod/elongated rosette ossicles in the tentacles. The tentacle ossicles of the new species comprise only oval, simple, open rosettes, 20–40 µm in length, while the other congeners possess rods/elongated rosette-shaped ossicles in the tentacles (very rarely also table ossicles). This new species has been collected from the shallow waters of western Japan living amongst boulder area in the intertidal-subtidal zone, at a depth of approximately 0–20 m.

A new kelp crab species of the genus Pugettia Dana, 1851 from Shandong Peninsula, north China is described and illustrated. Pugettia longipes n. sp. resembles P. ferox Ohtsuchi and Kawamura, 2019 and P. quadridens (De Haan, 1837), but can be distinguished by many morphological and morphometric characters. These include the shape of the basal antennal article, shorter cheliped merus, longer ambulatory legs (first legs longer than chelipeds in merus length), the structure of male first gonopod, and the different ontogenetic patterns of changes in the male chelae. A taxonomic key to all the upper subtidal species of Pugettia distributed in East Asian waters and P. longipes n. sp. is also provided.

Three species of nemerteans, Balionemertes cf. australiensis Sundberg, Gibson, and Olsson, 2003 (Palaeonemertea), Prosadenoporus olympiae sp. nov. (Hoplonemertea: Eumonostilifera), and Coella gloriae sp. nov. (Hoplonemertea: Polystilifera: Reptantia), are reported based on material collected intertidally at a rocky shore in Cebu Island, Republic of the Philippines. Cytochrome c oxidase subunit I (COI) barcode sequences of these species have earlier been published elsewhere. The Cebu specimen that is herein identified tentatively as Balionemertes cf. australiensis posseses i) small black dots on the ventral body surface, ii) a neurochord in the lateral nerve, iii) serial rhynchocoelic septa, and iv) nephrostomes, characters that were not mentioned in the original description of the species from Australia; the exact species identification requires barcode sequences from topotypes. Prosadenoporus olympiae can be differentiated morphologically from other congeners by having three accessory-stylet pouches; when alive, worms of this species showed negative hydrotaxis. Coella gloriae differs from all the reptantic polystiliferans by having i) four rows of the eyes, ii) the cephalic furrows, iii) no dorsal marking, iv) separate mouth and proboscis openings, v) blind-ending extracerebral vessels, vi) non-forked fibre core in the dorsal ganglia, vii) the subdorsal nerves, and viii) the cerebral organs partly overlapping the brain.

Three species of the family Euphylliidae (Cnidaria, Anthozoa, Hexacorallia, Scleractinia) have been formally recorded for the first time from the Ryukyu Islands, Japan, based on specimens. Their unique polyp morphology, such as the combination of extended tentacle, are considered to be useful for taxonomy at the species level in genus Fimbriaphyllia Veron and Pichon, 1980 and Euphyllia Dana, 1846. One reason that their distribution might have been overlooked is the insufficiency of environmental surveys, including turbid, sheltered, and upper mesophotic environments.

Two specimens of Ophiopsila cf. polyacantha H. L. Clark, 1915 are described from approximately 15 m water depth at Kakeromajima island, Amami Islands in southwestern Japan. The species occurs on sandy bottoms with the disc buried and the arms extended above the substratum. Bioluminescence and burrowing behavior are described. The specimens are clearly morphologically different from the two species of Ophiopsila Forbes, 1843 previously recorded from Japan. The new Japanese name “Kin-habu-toranoo-kumohitode” is proposed.

Six decapod crustacean species, including one gebiidean and five anomurans, are reported as new to the marine fauna in the Sea of Japan based on material collected from the coast of Tottori Prefecture, western Japan. Among them, the munidid squat lobster Paramunida tricarinata (Alcock, 1894) is new to the Japanese fauna. In addition to the six species, the occurrence of the diogenid hermit crab Paguristes versus Komai, 2001 in the Sea of Japan is confirmed on the basis of specimens newly obtained from Tottori Prefecture. The current knowledge on the fauna of Gebiidea and Anomura in the western Japanese coast of the Sea of Japan is also briefly summarized.

A faunal investigation of shallow-water (<50 m) comatulids of the Ashizuri-Uwakai Sea, Shikoku Island, southern Japan was performed between mid-2011 and early 2015, using scuba. It revealed that 30 species of seven families are distributed in the area, including two tropical species, Clarkcomanthus mirabilis (Rowe, Hoggett, Birtles, and Vail, 1986) and Clarkcomanthus mirus (Rowe, Hoggett, Birtles, and Vail, 1986) that are recorded in Japanese waters for the first time, as well as two species recently described during the research. Seventy-five percent of the listed species are tropical species, and 70% are shared with the fauna of the Ryukyu Islands, the southernmost part of Japan. These results agree with the general feature of the Ashizuri-Uwakai Sea in which the biota is strongly influenced by the Kuroshio Current flowing from the south.

Key Words:feather stars, marine fauna, new records, Kuroshio Current.

A new species of flabelligerid polychaete, Lamispina miurai sp. nov., has been described based on material collected at a depth of 226–228 m in the Pacific Ocean, off Aomori, Japan. Lamispina miurai sp. nov. can be differentiated from other congeners by the following features: i) the body is not covered with sand or large sediment particles; ii) the lamispines are present on the chaetiger 4 and succeeding chaetigers; iii) the tip of the lamispine is curved and subdistally serrated; iv) the cephalic cage is formed by chaetigers 1–3; and v) the length of the cephalic cage is twice as long as the body width.

An ovigerous female of the rare cymothoid isopod, Elthusa splendida (Sadowsky and Moreira, 1981) was discovered in a museum specimen of Japanese spurdog Squalus japonicus Ishikawa, 1908 collected from the East China Sea. This cymothoid species was previously known only from the type locality, off southern Brazil, the western South Atlantic. Therefore, the new record in the East China Sea represents the almost maximum distribution range extension on the earth (i.e., the antipodes). In addition, the present female is the largest specimen of this species on record (57.9 mm in total length). We described the East China Sea specimen along with verification of the presence of four pits on pereonite 1, an important diagnostic character of the species, using a 3D measurement system.

Dactylogyrus petruschewskyi Gussev, 1955 (Monogenea: Dactylogyridae) was found infecting the gills of Megalobrama amblycephala Yih, 1955 (Cypriniformes: Cyprinidae: Cultrinae) that was sampled from the Ono River flowing into Lake Kasumigaura in Ibaraki Prefecture, central Japan. This is the first record of this monogenean from Japan, and this parasite was most likely introduced and established along with M. amblycephala from China into Japan. The 28S rDNA sequence of D. petruschewskyi is available in the database but not based on a published study. We analyzed molecular data based on newly collected specimens, and the obtained sequence corresponded to the available sequence.

A single specimen (31.7 mm in standard length) and an underwater photograph of Acentrogobius limarius Allen, Erdmann, and Hadiaty, 2015 (recently described from Batanta Island, West Papua, Indonesia) from Amami-oshima and Iriomote-jima islands, Ryukyu Islands, Japan, respectively, represent the first Northern Hemisphere records of the species, the former being the northernmost record. A full description of the specimen is given and the new standard Japanese name “Hokosaki-kirara-haze” proposed for the species.

Recent views on the goals and methods of historical biogeography have sought support in the distinctions between three phases of biogeographic study and between three aspects of biogeographical hypotheses that were made by Ian. R. Ball in 1975 and 1990. Here it is shown that these recent perspectives on Ball’s philosophy concern misinterpretations of his views that, therefore, are incorrectly used in the development of a theoretical framework for the formation and testing of biogeographic hypotheses. This re-evaluation of Ball’s views also serves as a template for a critical appraisal of several recently published standpoints on the goals and methods of biogeography. Recent panbiogeographic studies postulate wide-spread ancestors in the explanation of present-day vicariant distributions. Wide-spread, even cosmopolitan, ancestral distributions also underlay early applications of taxon-cladistic biogeography, but this notion of primitive cosmopolitanism has been abandoned and replaced by the more realistic assumption that the ancestor had a more restricted distribution. The notion of primitive cosmopolitanism, or at least greatly widespread ancestors, has resurfaced in historical biogeographic hypotheses featuring in modern panbiogeographic studies. This explanatory model is combined with the concept of polymorphic ancestors, which may give rise to parallel evolution of descendant taxa through the process of recombination of ancestral characters. Ample parallelism is well-known in phylogenetic analyses, while it is known also from cases of relatively recent urban evolution. Recent insights into developmental genetics, character identity, and homology concur with the polytopic and polytypic biogeographic model. Progress in historical biogeography is expected to be based on calibrated timetrees and on a pluralistic approach in which the boundaries of various biogeographical hypotheses are clearly demarcated, thus delimiting the domain in which potentially falsifying observations are applicable.

Females of the lernaeopodid copepod Salmincola markewitschi Shedko and Shedko, 2002 were collected from the buccal cavity of whitespotted char, Salvelinus leucomaenis (Pallas, 1814), in a mountain stream of Nagano Prefecture, Honshu Island, the largest main island of Japan. The females are described as the first record of S. markewitschi from Honshu Island, because the species has so far been reported from the Russian Far East and the southern Kuril Islands east of Hokkaido Island, Japan. The copepod previously reported as Salmincola californiensis (Dana, 1852) from the same host species from the same stream and a nearby hatchery is herein regarded as S. markewitschi. As the species closely resembles Salmincola carpionis (Krøyer, 1837), it is desirable to re-identify the copepod specimens reported before as S. carpionis from Japanese salmonids, especially Salvelinus spp. Contraction of the formalin-fixed and preserved specimens, especially their second maxillae, of S. markewitschi is discussed. Information on the known hosts and distribution records of S. markewitschi is also compiled.

While examining specimens identified as Paracaristius maderensis (Maul, 1949) at the Scripps Institution of Oceanography Marine Vertebrate Collection, we encountered an individual of the genus Platyberyx Zugmayer, 1911. This specimen was collected in the Central Pacific Ocean, 900 km east of Wake Atoll during the Naga Expedition 1959–1961. We identified the specimen as Platyberyx rhyton Stevenson and Kenaley, 2013, and it represents the first record of this species outside of Japanese waters. This is a range extension of around 3400 km east for this species, as well as the first record of a juvenile individual and the fourth record of the species overall. We provide a morphological description and comparisons to the three previously known adult specimens.