Recently rediscovered in the Hokkaido University collection, the holotype and single paratype of Lycenchelys brevimaxillaris Toyoshima, 1985 were found to differ from the original description of the species in the following characters: posision of posterior end of upper jaw and numbers of anal fin rays, gill rakers on lower gill arch, suborbital, mandibular, and preoperculer pores, and vomerine and palatine teeth. Because no significant differences were found in the counts, proportions, and other characters (e.g., interneural space insertion of first dorsal fin pterygiophore), including body color, between these type specimens and L. melanostomias Toyoshima, 1983, the recently demonstrated synonymy of the two names is confirmed. The holotype and paratype of L. brevimaxillaris have been registered in the collections of Hokkaido University, Hakodate (HUMZ), and the National Science Museum, Tokyo (NSMT), respectively.

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A species of freshwater sculpin, Japanese name "Kibire-kajika", inhabits some rivers of the Korean Peninsula. Although this species has been recorded under the name Cottus poecilopus Heckel, 1840 or the incorrect subsequent spelling C. poecilopterus, it is shown by comparison with the type specimens to differ from both subspecies of C. poecilopus (C.p. poecilopus Heckel, 1840 and C.p. volki Taranetz, 1933). Moreover, it is distinguished from all other members of the genus Cottus by the following combination of characters: lacking palatine teeth, pectoral fin rays not branched even in adults, lateral line complete, terminal pores of mandibular sensory canals opening separately on either side of symphysis, body almost naked, back and sides lacking dark vermiculations, pelvic fin with bands or white roundish marks bordered with a blackish line, innermost ray of pelvic fin longer than 60% of length of longest ray, second dorsal fin rays numbering 18-21, anal fin rays 14-17, pectoral fin rays 12-13, and vertebral number 34-36. We describe this species here as a new species, Cottus koreanus, on the basis of 28 specimens collected from several rivers in Korea.

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A new species of cyclopoid copepod, Allocyclops (Allocyclops) austronipponicus, is described from a freshwater habitat in Okinawa Island, Japan. This is the first record of the genus Allocyclops from Asia. The new species is distinguished from its congeners by having the following combination of character states: (1) antennal seta representing exopod present; (2) maxillule with two-segmented palp; (3) legs 1-4 each with inner coxal seta; (4) distal endopodal segment of leg 4 with three inner and one outer setae and two apical spines; and (5) seta present on remnant of proximal segment of leg 5, this seta short in comparison to length of somite.

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Three similar species of water mite in the subgenus Hygrobates (genus Hygrobates) are reported from middle Honshu, Japan. These include two recently described lacustrine species, Hygrobates (Hygrobates) biwaensis Tuzovskij, 2003 and H. (H.) rarus Tuzovskij, 2003, which are known only from Lake Biwa, and one new fluvial species, H. (H.) capillus sp. nov. The new species is distinguished from the other two by the truncate P-2 ventral projection; the female genital plates being longer than the genital opening and extending to the post-genital sclerite; the anterior border of the flat male genital plate; and the larger body size (408-603μm). Two or three setae are confirmed to be present on the female pre-genital sclerites in the three species reported herein; this character state has never so far been recorded in any member of this subgenus.

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A new boring sponge, Cliona reticulata sp. nov., is described from coral reefs of the Ryukyu Islands, southwestern Japan. This species differs from closely related taxa, such as C. aprica Pang, 1973, C. caribbaea Carter, 1882, C. orientalis Thiele, 1900, and C. tenuis Zea and Weil, 2003, primarily in its apparent inability to undergo papillary fusion and thus form incrustations on top of the excavated substratum, the lack of symbiotic dinophycaeans (zooxanthellae), and the unusually large size of the pits caused by cellular etching. A new type of thin, long and wavy spiraster found in the holotype is another distinctive character. The morphology of the substratum excavated by the sponge is also considered to be of diagnostic value. This is the second species of the genus Cliona reported from the Ryukyu Islands.

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A new species of dicyemid mesozoan, Dicyema koshidai sp. nov., is described from Shiroika, Sepioteuthis lessoniana Lesson, 1830, collected off Uozu in Toyama Bay and off Mihonoseki in the Sea of Japan. The dicyemid is a large species that reaches a length of about 5000μm. The vermiform stages are characterized as having 32-40 peripheral cells, a conical calotte, and an axial cell that extends to the middle of the metapolar cells. Infusoriform embryos consist of 37 cells; two nuclei are present in each urn cell and the refringent bodies are solid. The dicyemids live in folds of the renal appendages of the cephalopod host. This is the second dicyemid species to be described from S. lessoniana. Additional details of the first species, D. orientale Nouvel and Nakao, 1938, are described. The dicyemid fauna in S. lessoniana is discussed.

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It is shown that the genus name proposed for a flatworm, Ichthyophaga Syromiatnikova, 1949, is not preoccupied by the name frequently used for a genus of fishing eagles, Ichthyophaga Lesson, 1843, since usage of the latter in modern ornithological publications is actually based on a subsequent misspelling or an unjustified emendation of the original generic name Icthyophaga Lesson, 1843. Despite this one-letter difference, a replacement name for the flatworm genus is necessary due to the prevailing usage in ornithology of the generic name spelled as Ichthyophaga. As replacement name the generic name Piscinquilinus nomen novum is proposed.

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