A new species of marine hatchetfish, Polyipnus surugaensis, is described based on a specimen collected from Suruga Bay, Japan. This species is distinguished from congeners by the following character combination: the 3rd supra-abdominal photophore is higher in position than the 2nd; the predorsal dark pigmented area does not reach to the median line of the body and is separated from the subdorsal dark pigmented area; the posterior vomerine shaft is toothless.

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For the systematic study of the gonostomatid fishes of the Diplophos taenia species complex, a total of 698 specimens was obtained from the three oceans. Four valid species were recognized: D. taenia Günther, D. proximus Parr, D. orientalis Matsubara, and D. australis sp.nov. The diagnostic characters are 90-100 total vertebrae (TV) (37-41 abdominal (AV) +52-60 caudal vertebrae (CV)) and 103-115 IC photophores (IC) for D. taenia, 85-90 TV (36-39 AV+48-52 CV) and 98-104 IC for D. proximus, 83-86 TV (33-35 AV+49-52 CV) and92-100 IC for D. orientalis, and 84-91 TV (33-37 AV+50-54CV) and 99-105 IC for D. australis. In addition to the above, D. proximus has larger orbital diameter (the proportion to head length 21-28%) than the other three species (15-23%) beyond 70mm in standard length. Due to wide distribution, D. taenia shows meristic variations: the numbers of TV, IC and anal fin rays (A) are smaller at lower latitudes and larger at higher ones in all oceans, and the number of A is smaller in the Atlantic (56-71) than in the other oceans (59-72) of the same latitude. Because of these variations, identification to species level is possible only area by area. The distribution of each of the four species is also distinct: D. taenia is a cosmopolitan between about 40°N and 30°S exclusive of the eastern tropical Pacific; D. proximus is endemic to the eastern tropical Pacific; D. orientalis is limited to the North Pacific transitional zone between about 30° and 40°N; and D. australis in a transitional zone of the Southern Ocean south of 20°S.

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All the fish specimens of Neoclinus bryope species complex collected from Okinawa Island including the 2 specimens already reported as N. bryope are referable to N. okazakii. Neoclinus nudus, hitherto known only from Taiwan, is newly recorded from Okinawa Island. These two species are redescribed on the basis of the specimens from Okinawa Island. The specimens from Okinawa are compared with those from Shirahama in the case of N. okazakii and with specimens from Taiwan as well as N. lacunicola and N. toshimaensis specimens from Shirahama in the case of N. nudus. The habitats of N. okazakii and N. nudus are clearly separated in the waters of Heshikiya, Okinawa Island and the habitat of either species is rather particular in that it is exceptionally unoccupied by blenniids which are flourishing in the coastal waters of the Okinawa Islands.

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From specimens collected in the western North Pacific, the early ontogeny of Psettina iijimae and Laeops kitaharae is described. Diagnostic characters of the genera throughout larval stages are also provided. It is suggested that these species are distributed on continental shelf or at the edge, and that they spawn between July and September.

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The development of squamation is described in four teleost species, Cichlasoma octofasciatum (Cichlidae), Poecilia reticulata (Poeciliidae), Barbus barbus (Cyprinidae) and Corydoras arcuatus (Callichthyidae). These observations are compared to previous descriptions of the squamation development in other species (mainly teleosts) known from the literature. Among teleosts, 7 different regions can be delimited on the body, each containing the sites of the first scale appearance. Some species have only one site (generally located on the caudal peduncle) whereas others have two or more. The possibility of the involvement of epigenetic factors to explain the existence of several sites of scale appearance and their localization on the body surface is discussed.

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The karyotype of the catfish, Parasilurus aristotelis, from Lake Trichonis, Greece, shows that the species has a diploid chromosome number of 2n=58. Comparison with published data on the karyotypes of other species belonging to Parasilurus shows the same chromosome number but different arm numbers. Reported karyological data of the European populations of Silurus indicate that they have a diploid number of 2n=60. A reduction in chromosome number is assumed to be connected with speciation and, therefore, Parasilurus probably forms a separate group from that of Silurus.

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The operculum may be divided into the proximal, the distal and the intermediate regions. The epithelium lining the inner surface of the operculum (EISO) and the opercular epidermis (OE) of these regions in Clarias batrachus show significant differences in their thickness, in the density, in the dimensions of mucous cells and club cells, and in the distribution of lymphocytes, melanocytes, taste buds and ampullary organs. These differences in structural organization are associated with the different conditions prevailing at these locations. Rich vascularization observed in the tissues underlying the OE has been correlated with assisting the fish in accessory respiration. In contrast, the tissues underlying the EISO are poorly vascularized. Accessory respiration in this region may not be so advantageous.

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Movement of the fluvial form of red-spotted masu salmon (1⁺ and older), Oncorhynchus masou rhodurus, was studied using mark-recapture methods in a Japanese mountain stream. Most (63-91%) adult salmon were recaptured in the pool in which they were marked. The rest of the salmon moved upstream or downstream<20m during the non-breeding period. The proportion of the salmon moving increased slightly during the breeding period, but did not exceed 66%. The distance moved was also more variable during this period. The proportion of the smaller salmon which moved was larger than that of the larger fish during the non-breeding period. Conversely, during the breeding period, larger fish moved more frequently. Sedentary behaviour and local movements of adult salmon seem to be affected by their social relationships.

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Embryonic and morphological development of larvae and juveniles of the amberjack, Seriola dumerili Risso, are described using specimens raised at Yaeyama Station (Ishigaki Island, Okinawa Pref.), Japan Sea Farming Association. The specimens obtained from brood fish (3 females, 3 males) were treated with gonadotropin and spawned on 6th of April 1987. The eggs of amberjack are pelagic, spherical in shape and 1.01-1.17mm in diameter. The yolk is roughly segmented and has a single oil globule 0.22-0.24mm in diameter. The perivitelline space is narrow. During development, a few melanophores and no xanthophores were observed on yolk. Hatching took place 35hrs. 15min. after spawning out at temperatures 23.1-23.7°C. The newly hatched larvae were 2.84-3.04mm in TL with 27 (13+14) myomeres and an oil globule anteriorly situated beyond the head. 3 days after hatching 4.00mm TL, the mouth opened. 10 days after hatching 4.26mm TL, small denticles appeared on the margin of the upper jaw and there were 1 anterior and 2 posterior preopecular spines. At 5.96mm TL, notochord was slightly flexed. Caudal, dorsal and anal fins with rudiments of rays appeared at 8.00mm TL. The specific numbers of all fin rays and spines were obtained in a juvenile 9.60mm TL. In a juvenile 34.25mm TL, 54 days after hatching, the characteristic brown band of amberjack had appeared on head. Some notable changes in relative growth were observed at 5mm and 15mm in TL.

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Under controlled laboratory conditions, the locomotor activity rhythms of four species of wrasses (Suezichthys gracilis, Thalassoma cupido, Labroides dimidiatus and Cirrhilabrus temminckii) were individually examined using an actograph with infrared photo-electric switches in a dark room at temper-atures of 21.3-24.3°C, for 7 to 14 days. The locomotor activity of S. gracilis occurred mostly during the light period under a light-dark cycle regimen (LD 12: 12; 06: 00-18: 00 light, 18: 00-06: 00 dark). The locomotor activity commenced at the beginning of the light period and continued until a little before the beginning of dark period. The diel activity rhythm of this species synchronizes with LD. Under constant illumination (LL) this species shows distinct free-running activity rhythms varying in length from 23 hrs. 39min. to 23 hrs. 47min. Therefore, S. gracilis appears to have a circadian rhythm under LL. However, in constant darkness (DD), the activity of this species was greatly suppressed. All the fish showed no activity rhythms in DD conditions. After DD, the fish showed the diel activity rhythm with the resumption of LD, but this activity began shortly after the beginning of light period. The fish required several days to synchronize with the activity in the light period. Therefore, S. gracilis appeared to continue the circadian rhythm under DD. In T. cupido, the locomotor activity commenced somewhat earlier than the beginning of the light period and continued until the beginning of the dark period under LD. The diel activity rhythm of this species synchronizes with LD. Under LL, four of the five specimens of this species tested showed free-running activity rhythms for the first 5 days or longer varying in length from 22 hrs. 54min. to 23 hrs. 39 min. Although the activity of this species was suppressed under DD, two of five fish showed free-running activity rhythms throughout the experimental period. The lengths of such free-running periods were from 23 hrs. 38min. to 23 hrs. 50min. under DD. Therefore, it was ascertained that T. cupido has a circadian rhythm. In L. dimidiatus, the locomotor activity rhythm under LD resembled that observed in T. cupido. The diel activity rhythm of this species synchronizes with LD. Under LL, four of seven of this species showed free-running activity rhythms throughout the experimental period. The lengths of such free-running periods were from 23 hrs. 07min. to 25 hrs. 48min. Although the activity of this species was suppressed under DD, three of five fish showed free-running activity rhythms throughout the experimental period. The lengths of such free-running periods were from 23 hrs. 36min. to 23 hrs. 41min. under DD. Therefore, it was ascertained that L. dimidiatus has a circadian rhythm. Almost all locomotor activity of C temminckii occurred during the light period under LD. The diel activity rhythm of this species coincides with LD. Under LL, two of four of this species showed free-running activity rhythms throughout the experimental period. The lengths of such free-running periods were from 23 hrs. 32min. to 23 hrs. 45min. Although the activity of this species was suppressed under DD, one of the four fish showed free-running activity rhythms throughout the experimental period. The length of the free-running period was 23 hrs. 21min. under DD. Therefore, C temminckii appeared to have a circadian rhythm. According to field observations, S. gracilis burrows and lies in the sandy bottom while T. cupido, L. dimidiatus, and C. temminckii hide and rest in spaces among piles of boulders or in crevices of rocks during the night. It seems that the differences in nocturnal behavior among the four species of wrasses mentioned above are closely related to the intensity of endogenous factors in their locomotor activity rhythms.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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A specimen of the filefish, Pervagor nigrolineatus, was collected from dead coral patches at a depth of 3 m in Zamami-jima, Kerama Islands (26°14'N, 127°19'E). This species is recorded for the first time from Japan. It has been known to be distributed in the tropical western Pacific from the Philippines to New Guinea (Hutchins, 1986). The present specimen is more similar in scale characters to the Philippine specimens than to the New Guinean ones.

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