Five specimens (10.4-86.5mm standard length) of the Indo-West Pacific flatfish Asterorhombus filifer Hensley and Randall, 2003 were collected at depths of 12-21 m on sandy bottoms at Yoron Island and Amami-oshima Island, Ryukyu Islands, Japan. These specimens represent the first records of A. filifer from Japan and the northernmost records of this species.

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Nine specimens of a flatfish collected from Western Australia were tentatively identified as Arnoglossus aspilos praeteritus Whitley, 1950. The original description of this subspecies is brief and the validity of the taxon had not been investigated, despite its inclusion in subsequent short notes and lists. Our examination of the new material and the type series of A. aspilos praeteritus reveals that this taxon clearly differs from the members of the genus Arnoglossus in having a well-defined interorbital space and split hypurals. It differs subtly from A. aspilos (Bleeker, 1851) in appearance, although both taxa closely resemble each other in most counts and proportional measurements. Arnoglossus aspilos praeteritus is herein redescribed and reassigned as a valid species of the genus Engyprosopon, viz., E. praeteritus. This species differs from other species of Engyrposopon in having a series of dark blotches on the dorsal and anal fins and a pair of small black blotches on the caudal fin, and by lacking sexual differences in morphology and coloration.

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Helcogramma ishigakiensis (Aoyagi, 1954), originally described as Lepidoblennius marmoratus ishigakiensis from the Ryukyu Islands, southern Japan, and subsequently regarded as a junior synonym of Helcogramma inclinata (Fowler, 1946), is redescribed here as a valid species. Helcogramma ishigakiensis is characterized by the following combination of characters: 13-15 (modally 14) second dorsal-fin spines; 28-39 pored lateral-line scales; 4-5+1+4-6 (typically 4+1+4) mandibular pores; anterior nostril tentacle unbranched; orbital tentacle simple; nape without scales; and bases of dorsal fins and entire caudal fin reddish in mature male. A synopsis of the other species of Helcogramma occurring in the Ryukyu Islands and a key to the Ryukyu species of the genus are provided.

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The shortfin pomfret, Brama pauciradiata Moteki, Fujita and Last, 1995, is redescribed based on six specimens collected off Mie Prefecture, Japan. Although this species was originally described based on 23 specimens collected off northwestern and northeastern Australia and off Hawaii, the largest specimen measured 81.8 mm SL and most of the type series are juveniles of less than 50 mm SL. The present specimens include five much larger specimens, of 103.8-160.1 mm SL. Distinct differences observed in some proportional measurements between the type series and the present larger specimens are regarded as ontogenetic changes because the countable characters agree well with those of type series and because the pattern of transformation in body shape of the present specimens and the type series of B. pauciradiata is similar to that of its congeners. The distance from the lowest part of the base of the pectoral fin to the insertion of the pelvic fin, and also the pale caudal peduncle saddle of preserved specimens, were regarded as diagnostic characters in the original description, but these characters are shared with congeners. A female specimen of 155.0 mm SL (FRLM 42111) is regarded as representing the minimum size of maturity because of the condition of its oocytes. The distributional range of B. pauciradiata extends from the eastern Indian Ocean to a wide area of the western-central Pacific Ocean.

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The genus Peristedion Lacepede, 1801 occurring around Japanese waters is reviewed, with 4 species described based on 157 Japanese specimens: Peristedion orientale Temminck and Schlegel, 1843, P. liorhynchus (Gunther, 1872), P. nierstraszi Weber, 1913, and P. amblygenys Fowler, 1938. The four species are distinguished from each other by the shape of the rostral projection, the position of the fourth sensory pore on the rostral projection, the number of branches on the filamentous barbel on the lip, the total number of chin barbels, and the shape of the perifacial rim. The present study records P. amblygenys in Japanese waters for the first time.

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A new scorpionfish, Sebastapistes perplexa, is described on the basis of 43 specimens from the Pacific coast of Japan, where it ranges from the Boso Peninsula to Shikoku, including the Izu Islands, in depths of 2-48 m. The new species is characterized by having 12-15 (mode 14) pectoral-fin rays; 33-42 (37) scale rows in longitudinal series; 4 or 5 (5) scale rows above the lateral line, 9-13 (10) scale rows below the lateral line; 3 or 4 (4) scale rows between the sixth dorsal-fin spine base and the lateral line; 3-5 (4) scale rows between the last dorsal-fin spine base and the lateral line; 2-4 (3) pre-dorsal scale rows; 11-17 (15) gill rakers; palatine teeth present; ctenoid body scales; simple anterior and posterior lacrimal spines; no lateral lacrimal spine or ridge; the first and second suborbital ridges fused to form a single ridge with one suborbital spine at its end; a median ridge on lower opercular spine; the opercular spines not covered by scales; and a dark blotch usually visible on the subopercle and pectoral-fin base (distinct in preserved specimens). Sebastapistes perplexa appears to be restricted to temperate waters whereas its congeners are primarily tropical and subtropical species. The new species is compared in detail to two congeneric species that share some diagnostic features with it, and to the sympatric S. strongia (Cuvier in Cuvier and Valenciennes, 1829).

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A new species of mud shrimp, Axianassa japonica (Gebiidea: Axianassidae), is described and illustrated on the basis of a single male specimen from Kushimoto, Wakayama Prefecture, Japan, collected at a depth of 15 m. It represents the first record of the genus from Japanese waters. Of the nine congeneric species it appears closest to A. heardi Anker, 2011, known from Queensland, Australia. The presence of two pairs of short longitudinal carinae on the anterior part of the carapace, the ventrally blunt pleuron of the first pleomere, and the presence of an incomplete suture on the uropodal endopod immediately distinguish the new species from A. heardi. The status of Axianassidae is briefly discussed, and an identification key to the species of Axianassa is provided.

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An adult male specimen of the amphibian acanthocephalan Acanthocephalus lucidus Van Cleave, 1925 was isolated from the intestine of a whitespotted char, Salvelinus leucomaenis leucomaenis (Pallas, 1814), collected from a stream in Aomori Prefecture, northern Japan. This represents the second record of fish infection by this species of acanthocephalan. The life cycle of A. lucidus is discussed, and the char is assumed to have become infected by preying on a frog harboring the specimen. The known vertebrate hosts of A. lucidus and the geographical distribution of this species in Japan and East Asia are tabulated.

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Five species of helminth endoparasite (two digeneans, Brachyphallus crenatus (Rudolphi, 1802) and Lecithaster gibbosus (Rudolphi, 1802); two cestodes, plerocercoids of Nybelinia surmenicola (Okada in Dollfus, 1929) and a tetraphyllidean; and an acanthocephalan, post-cystacanths of Bolbosoma sp.) were found in adults of Arctic lampreys Lethenteron camtschaticum (Tilesius, 1811) arriving in the lower part of the middle reaches of a river in Hokkaido, Japan, for spawning after a period of growth in the sea. These parasites are all common species previously reported from various marine fishes in the North Pacific and all have complex life-cycles involving host-to-host transmission via a predator-prey relationship. To have become infected with these food-borne parasites, Arctic lampreys need to have ingested various body parts of infected prey fishes at sea. Consequently, the endoparasites recovered suggest that the Arctic lamprey has a role as a predator in marine ecosystems.

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The dactylogyrid monogenean Bivaginogyrus obscurus (Gussev, 1955) is redescribed from the gills of two cyprinids, Pseudorasbora pumila pumila Miyadi, 1930 in Nagano Prefecture and P. parva (Temminck and Schlegel, 1846) in Ibaraki Prefecture. These are the first records of this parasite in Japan. Pseudorasbora p. pumila, which is endemic to central Japan, represents a new host record for B. obscurus. This monogenean is the first helminth and the second parasite discovered from wild P.p. pumila.

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The ancyrocephalid monogenean Salsuginus seculus (Mizelle and Arcadi, 1945) was found infecting the gills of mosquitofish, Gambusia affinis (Baird and Girard, 1853), from Okinawa, Aichi, Tokushima, and Kyoto prefectures in Japan. These are the first records of S. seculus from Japan. This parasite was most likely introduced along with mosquitofish from Texas (USA) through Hawaii and Taiwan into Japan in the late 1910s. It appears to have low salinity tolerance.

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