A specimen of Acrochordidae, Acrochordus granulatus (Schneider, 1799) (Squamata), which was collected on Amamioshima Island, Ryukyu Archipelago, Japan in 1938, was discovered in the historical zoological collection of the Kyoto University, Japan. The specimen was originally included in the “Third Higher School collection” and is now kept in the Kyoto University Museum. The specimen represents the first record of this species from Japan. Morphology of the specimen is described, and the migration route of this individual is briefly discussed.

Sampling of rice fields in Kanagawa Prefecture, Japan, yielded an undescribed species of the non-marine ostracod genus Sarscypridopsis McKenzie, 1977. Small marginal denticles on the left valve give this species its name: Sarscypridopsis denticulata n. sp. Most species of the genus Sarscypridopsis are restricted to Africa, and based on morphological characters, the closest congener of this new species is native to Botswana. We therefore conclude that this species is probably not native to Japan, and it joins six other non-marine ostracod species that are probably or possibly alien or invasive in Japan. Including the new species, four of these are associated with rice fields. All specimens of Sarscypridopsis denticulata n. sp. are female, and one of the antennal claws (claw G2) is more robust and with better developed serration compared with the other antennal claws. This is a feature of several Cypridopsinae lineages, but in females only. An overview of the zoogeographical distribution of the genus is provided.

Ricuzenius toyamensis Matsubara and Iwai, 1951 was originally described on the basis of eight specimens collected from Toyama Bay, the Sea of Japan coast of central Honshu Island, Japan. The species has subsequently been considered as a valid species of the genus Icelus Krøyer, 1845, diagnosed by the following characters: supraocular and parietal spines absent; nuchal spine blunt and indistinct, covered with skin; uppermost preopercular spine unbranched; mid-sized scales scattered (not in rows) above and below lateral line; belly naked; minute ctenoid scales on upper part of maxillary; lateral line scales large, tubular, bearing spinules on dorsal and posterior margins; and lower jaw slightly protruding anteriorly. However, examination of the type specimens of Icelus rastrinoides Taranetz in Schmidt, 1935, a northern Sea of Japan species, showed them to be consistent with the holotype and paratypes of I. toyamensis. Accordingly, I. rastorinoides is regarded as a senior synonym of I. toyamensis, with the lectotype of the former being designated herein. The species is redescribed in detail on the basis of the types of both nominal species plus non-type specimens, with a note on geographic variations in dorsal- and anal-fin ray counts, which reflect Jordan’s rule.

The taxonomic status of millipedes of the genus Spirobolus Brandt, 1833, referred to as “Yaeyama-maruyasude” from the Yaeyama Islands, Ryukyu Islands, Japan, was unresolved. We assess the taxonomic status of these Yaeyama Spirobolus sp. using an integrated morphological and molecular approach, and describe them as a new species, S. akamma sp. nov., for which partial sequences of the nuclear 28S ribosomal RNA, mitochondrial cytochrome c oxidase subunit I, and 16S ribosomal RNA markers are provided. This new species differs from continental China and Taiwan endemic congeners in anterior gonopod morphology (in having an elongate and subtriangular coxa, and a pentagonal mesal sternal process), posterior gonopod morphology (in having a coronoid prefemoral endite with rounded distal end, and an elongate telopodite), and in having four serrations on the cyphopod lateral flange.

Two distinctive species of Amphipoda are described from the Ariake Sea in Japan. Scutischyrocerus japonicus sp. nov. (Family Ischyroceridae) is characterized by the cylindrical shape and the shield-like coxae 2–5. This new species differs from S. scutatus Myers, 1995 in the uropods with peduncles bearing many plumose setae. In the second species, Ledoyerella clavata (Hirayama, 1984) comb. nov. (Family Kamakidae), the lateral cephalic lobe is strongly produced, and the gnathopods 1, 2 of both sexes are the same size, with the propodus being almost as long as the carpus. This species can be distinguished from its congeners by the heavily setose posterior margins of pereopods 6, 7 bases. Ledoyerella spinosa Ren, 2006 is synonymized with this species.

A new shallow-water species of the genus Odontohenricia Rowe and Albertson, 1988 is described from the coast of Rishiri Island, Hokkaido, northeastern Japan. The new species is different from other congeners in having intermarginal series extending 2/3 of the arm length, abactinal spines more than 0.3 mm in length, and oral spines with opaque and serrated tips.

Two specimens of the carangid fish Scomberoides tala (Cuvier, 1832) (141.5–411.0 mm in standard length, 151.9–433.0 mm in fork length), collected from northern Miyazaki Prefecture and the Yaeyama Islands, southern Japan, represent the first specimen-supported Japanese records and northernmost record of the species, previously recorded from the east coast of South Africa, Arabian Sea, Bay of Bengal, Indo-Australian Archipelago, Australia, Gulf of Thailand, and South China Sea. In addition, the distribution of S. tala in Japanese waters was assessed on the basis of a previous photographic record, and the Japanese name for the species was discussed.

In this study we describe one new species of Dactylogyrus Diesing, 1850 and three new species of Bivaginogyrus Gussev and Gerasev in Gussev, 1985 (Monogenea: Dactylogyridae) from two freshwater fishes Gnathopogon elongatus elongatus (Temminck and Schlegel, 1846) and G. caerulescens (Sauvage, 1883) (Cypriniformes: Gobionidae) endemic to Japan. Further, G. elongatus is a new host record for Paradiplozoon skrjabini Achmerov, 1974 (Monogenea: Diplozoidae). Dactylogyrus tamoroko n. sp. is most similar to D. chenjiagengi Zhang in Zhang, Zhou, and Wen, 1990, D. clypeatus Gussev, 1955, and D. gnathopogonis Yamaguti, 1963; it differs from these three congeners by the bifurcate base of the accessory piece. Bivaginogyrus japonicus n. sp. is close to D. polylepidis Alvarez Pellitero, Simon Vicente, and Gonzalez Lanza, 1981, but it can be separated from the latter species based on its uniform-sized marginal hooks. The new species was connected to the cartilage tissue of the gill using filament-like structures, which are assumed to be derived from secretions of the reservoirs associated with each marginal hook. Bivaginogyrus cingulatus n. sp. resembles D. navicularis Gussev, 1955, D. trullaeformis Gussev, 1955, and D. imberbis Wu and Wang, 1983, but the new species is distinguished from these three species by having its inconspicuous outer roots. Bivaginogyrus exiguus n. sp. is comparable to D. pandus Wu and Wang, 1983 and D. colpodes Wu, Wang, and Song, 1983, but differs from these two species in having a shorter penis. Molecular phylogenetic analysis indicates that Bivaginogyrus is a paraphyletic group and shows affinity to “Dactylogyrus” species parasitic on gobionid fishes. However, most of those closely related Dactylogyrus species are yet to be described for their internal morphology and should accordingly be redescribed. The three new species of Bivaginogyrus are assumed to have been co-introduced along with G. e. elongatus into non-native regions of this host.

Although the members of the genus Telmatactis Gravier, 1916 have been reported from broad area of the world including Japanese waters, the localities of the species have been limited to shallow areas. In this study, we report a new species in this genus, Telmatactis profundigigantica sp. nov., collected from the deeper area than 200 m of the East China Sea off Okinawa Island, discovered by ROV, and taken care of in Okinawa Churaumi Aquarium. This new species is chiefly characterized by its comparatively huge size of its body, over 10 cm in diameter and height, far larger than the other known species of this genus. Moreover, this species has characteristic multiple-headed tentacles and large cnidae in its acrospheres. In the present article, we also discuss the severe toxicity of this species and touch on the ecology of deep-sea anemones.

Three specimens of Ophioteichus multispinum H. L. Clark, 1938 are redescribed from approximately 2.3–12.6 m water depth at Sabiura, Kushimoto, Wakayama Prefecture in central Japan. The species occurs completely buried on sandy bottoms. Ossicle morphology is described. Based strictly on images, we present in situ occurrence of the genus Ophioteichus H. L. Clark, 1938 from the intertidal regions of Susami, Wakayama Prefecture, and Tosashimizu, Kochi Prefecture.

A single specimen of apogonid fish, Pristiapogon taeniopterus (Bennett, 1836) (Actinopteri: Kurtiformes) previously reported from Micronesia, Polynesia, Melanesia, the Hawaiian Islands, Madagascar and Indian Ocean, was recently caught at Minamidaito Island, Okinawa Prefecture, Japan. This specimen is the first record of the species from the Northwest Pacific including Japan and is now the most northerly record. Pristiapogon taeniopterus differs from its congeners in having developed gill rakers 15–17; circumpeduncular scales 15–18; upper-jaw length 17.9–21.5% SL; distinct dark stripes on both dorsal, anal and both lobes of caudal fin; dark vertical bar posterior to the base of caudal fin incompletely developed or interrupted at the central portion of the fin; dark band or blotch on posterior part of caudal peduncle just anterior to caudal-fin base; and pectoral-fin rays usually 13. The new standard Japanese name “Sumihiki-ishimochi” is proposed for the species.

Fifteen specimens (70.9–95.5 mm standard length) of the Indo-Pacific species Scorpaenodes corallinus Smith, 1957, previously recorded from Mozambique, Tanzania, Kenya, the Seychelles, Indonesia, Australia, the Hawaiian Islands, New Caledonia and French Polynesia, and recently collected from Okinawa Island (Okinawa Islands) and Yoron Island (Amami Islands), represent the first Japanese records of the species. Examination of a wide range of specimens indicated that the presence of coronal spines (formerly considered diagnostic of the species) was inconsistent. The new standard Japanese name “Ichigo-isokasago” is proposed for the species.

A subterranean millipede species, Antrokoreana gujoensis Masuda, 2010, is redescribed based on specimens newly collected around its type locality, in the limestone area of Mino Terrane on Honshu Island, Japan. Males of A. gujoensis were originally described as having no penes, but nonetheless, the examined specimens clearly demonstrate that this species possesses the penes behind leg-pair 2. An emended diagnosis of this species and a key to all eight currently recognized species of Antrokoreana is provided.

The cystidicolid nematode Salvelinema walkeri (Ekbaum, 1935) is a swim bladder parasite of freshwater salmonids in western North America, ranging from northern California to southern British Columbia. This parasite was found from two age-2.0, juvenile coho salmon Oncorhynchus kisutch (Walbaum, 1792) caught in the southern central Gulf of Alaska in December 1992. This represents the first record of S. walkeri from salmonids caught in offshore waters of the North Pacific Ocean. The two coho salmon harbored as many as 1053 and 278 nematodes, respectively, but there was no significant difference in the condition factor between infected and uninfected fish. The recovered nematodes are highly likely to have been alive in the host swim bladder when the fish were caught because their bodies were in good condition. Based on the observations in this and other papers, S. walkeri is inferred to survive throughout marine residence of salmonids after these fish are infected in streams and enter the sea. While the usefulness of S. walkeri as a stock discrimination tool is less than that of current methods employed for a similar purpose, the potential use of this freshwater parasite as a biological tag is also discussed for studying the ecology of ocean-migrating salmonids.