A new dasyatidid stingray, Dasyatis izuensis sp.nov., from Japan is described on the basis of specimens collected from the Izu Peninsula. The new species is distinguished by having the following characters: diamond-shaped disc; dorsal tail keel; white ventral tail fold, its length 24.6-32.3% of disc width; short preorbital snout length, 14.1-18.7% of disc width; smooth body even in adults except for a row of 2-6 small tubercles before tail spine; and 18-20 intestinal valve turns.

View full abstract

A new subspecies of the ayu, Plecoglossus altivelis ryukyuensis, is described on the basis of specimens from Amami-oshima and Okinawa Islands, the Ryukyu Islands, Japan. This new subspecies is distinguished from P. altivelis altivelis by the fewer numbers of pectoral fin rays, longitudinal scales and scales above and below the lateral line, and also by the unique electrophoretic mobilities of several enzymes.

View full abstract

Three species of the soldierfish genus Ostichthys have been collected in the Society Islands at depths of 300-420m: O. archiepiscopus and O. sandix are new records for the South Pacific, and O. ovaloculus is described as new from one specimen taken off Tahiti. It is distinctive in having XI, 16 dorsal rays, 15 pectoral rays, 38 lateral-line scales (other species of the genus with 27-30), 3^1/2 rows of scales above the lateral line, a straight dorsal head profile, long snout, and oval eye; color when fresh, bright red, the centers of scales whitish, resulting in longitudinal banding on the body.

View full abstract

Four new tilefishes of the genus Branchiostegus (Branchiostegidae) are described from southern Indonesia and northwestern Australia. These species are clearly distinguished from their congeners by combinations of: colouration, fin height, jaw length and position, shape of the preoperculum and caudal fin, body proportions and meristics. A key to all 16 species known world-wide, figures of 15 species, and a summary of their synonyms are presented.

View full abstract

Three new species of the sciaenid genus Atrobucca are described: A. kyushini from off Borneo, differs from all known congeners in having no swimbladder appendages enveloping the bladder, no forward directed branches from the ventral limbs of the appendages, a long tube-like last appendage parallel to the bladder wall and a pale mouth lining; A. brevis from off northern Australia and Papua New Guinea, is distinguished by its short pectoral fin (less than 23%SL) and pleural rib on the 11th vertebra; A. adusta from Papua New Guinea, is distinctive in having a low dorsal soft ray number (23-24) and long caudal peduncle (27-30%SL). Atrobucca Chu, Lo et Wu is redefined to accommodate the new species: the genus is principally characterized by the swimbladder appendages divided into developed dorsal and ventral limbs, and the only slightly curved sulcus tail of the sagitta. A key and diagnoses are provided for all known species of Atrobucca.

View full abstract

A new gobiid fish, Eviota lacrimae is described, on the basis of specimens collected from Cape Sata, Japan. This new species is distinguished from other species of the genus by the following characters: lacking IT and POP pores of the sensory organ; pelvic fin I, 4 and its fin membrane reduced between rays; fourth soft ray of pelvic fin with two branches.

View full abstract

An undescribed goby has been collected from several localities in the western tropical Pacific, from Japan to Australia. This species is described as a new species, Fusigobius signipinnis.It differs from other species of Fusigobius in pectoral ray counts, colouration, largely separate pelvic fins, and shape of the first dorsal fin. The species is found in groups on sand, frequently flicking its first dorsal fin. Males are larger than females in mean size. Sex ratios are uneven, and females are twice as numerous as males.

View full abstract

The ophidiid genus Glyptophidium is revised on the basis of 280 specimens. The seven recognized species fall into two well-defined species-groups: I. argenteum species-group with argenteum Alcock, 1889, effulgens sp.nov. and lucidum Smith et Radcliffe, 1913 is characterized i.a. by having 1 ray in each ventral fin, 1 median basibranchial tooth patch, 11 precaudal vertebrae, origin of dorsal fin above vertebrae nos. 3-4. II. macropus species-group with macropus Alcock, 1894 (lectotype selected), longipes Norman, 1939, oceanium Smith et Radcliffe, 1913 and japonicum Kamohara, 1936 (re-established and neotype described) is characterized i.a. by having 2 rays in each ventral fin, 2 median basibranchial tooth patches, 12-13 precaudal vertebrae, origin of dorsal fin above vertebra no. 1 or in front.

View full abstract

Comparative study on the distribution of six species of bitterling in a creek in Fukuoka Prefecture was carried out. The upper part of the creek was fluvial, and the lower part stagnant. Acheilognathus lanceolatus, A. tabira subsp.(b) of Nakamura (1969), A. rhombeus and Rhodeus atremius showed wide distribution in the creek throughout their life. A. limbatus seemed to be a fluvial species, and R. ocellatus smithii a lentic species. In the spawning season, however, all the species of bitterling, excepting R. o. smithii, probably possess a common spawning ground in which mussels occur at a relatively high density. Adult females of A. lanceolatus, A. tabira subsp.(b) and R. atremius without ripe eggs aggregated in the lower, stagnant parts of the creek. Most juveniles of these species and of A. rhombeus seemed to grow in the lower part of the creek, and then migrate upward untill their spawning season. No species among the same phylogenetic group has the same set of the life modes (spawning season, spawning sites, aggregation of females without ripe eggs in the lower part of the creek and probability of upstream migration of 0-year-old fish toward spawning sites).

View full abstract

Morphometric and karyotypic studies were made on two species of ricefishes collected from Yunnan, southwestern China. Oryzias latipes from Yunnan had the same morphological and karyological characteristics as O. latipes collected from eastern China. The Yunnan populations had 2n, 46 chromosomes consisting of 3 metacentric, 8 submetacentric, 2 subtelocentric, and 10 acrocentric pairs, the arm number (NF) being 68 (2n=46, NF=68, 3M+8SM+2ST+10A). The karyotype was characterized by having a “large” metacentric pair and nucleolus organizer regions (NORs) on the short arms of a submetacentric pair. Oryzias minutillus from Yunnan had the same morphological characteristics as O. minutillus from Thailand and Burma, although the karyotype was different from that collected from Thailand. The Yunnan population had 2n, 42 chromosomes consisting of 21 acrocentric pairs, NF being 42 (2n=42, NF=42, 21A). The karyotype was characterized by having NORs at the telomeric regions of an acrocentric pair. Oryzias latipes occurs widely on the eastern Yunnan Plateau where the climate is temperate or subtropical, whereas O. minutillus is found in Xishiangbanna, the southern low mountain areas of Yunnan, where the climate is tropical.

View full abstract

The morphology and innervation of the six oculomotor muscles in the gobiid fish Tridentiger trigonocephalus are described. Every rectus muscle is composed of two types of muscle fibres. Muscles attach onto the cartilaginous or fibrous sclerotica. Oblique muscles attach onto the ethmoidal plate; recti muscles attach onto the parasphenoid or a thick fibrous membrane. There is no myodome. The common oculomotor nerve is composed of four bundles, the trochlear and the externus of two. The two kinds of fibres of the lateral rectus and the two distinct bundles of the nerve VI suggest a possible homology between this muscle in fishes and the lateral rectus +retractor bulbi in mammals.

View full abstract

The micropyles and their surrounding structures of pelagic fish eggs of nine species were examined and compared using a scanning electron microscope (SEM). The surface of the egg membrane possesses uniformly distributed pores. However, Lateolabrax japonicus possesses a number of small knobs. The region of the micropyle of fish eggs examined is characterized by a circular elevation in which the pores are larger than those on the other parts of the egg membrane. In contrast, Kareius bicoloratus egg has no elevation and possesses uniform pores to the edge of the micropylar canal. The funnel-like structure is seen in the opening of the micropyle in Sardinops melanostictus, Saurida elongata, Sillago japonica, Parapristipoma trilineatum, Hypodytes rubripinnis and K. bicoloratus. These specific features of the micropyle may be used for the identification of pelagic eggs.

View full abstract

The spawning and subsequent copulating behavior of the elkhorn sculpin (Alcichthys alcicornis) were observed in an aquarium. Soon after the female was introduced into the tank, the male approached and initiated courtship behavior by unfolding all fins. Females which carried ovulated eggs eventually accepted the male and spawning progressed. Females which had not ovulated, repeatedly rejected the male's advances. The onset of spawning in the female was indicated by fluttering of the pectoral fins and successive horizontal undulations of the posterior trunk which served to sweep the spawning site. The laying of several thousand eggs was preceded by the female taking several large inhalations of water through the mouth and a slight raising of the posterior trunk. The male continued various behavior related to courtship while the female approached spawning. After spawning, the female smoothed the egg mass into a thin layer by using the posterior trunk and anal fin. After spawning, and while the female flattened the egg mass, the male copulated repeatedly. No copulation was observed prior to spawning. Semen was observed to be emitted from the tip of the penis and to leak from the female's genital pore. Eggs were fertilized externally by the emitted sperm in the case of females which had no prior copulating experience in the present breeding season. The entire reproductive behavior of the pair ceased, as the female left the spawning site after flattening the egg mass. The male remained near by, but did not aerate the eggs. During the breeding season, the area around the female's genital pore and along both sides near the base of the anal fin became slightly distended and soft by the accumulation of a serous fluid. It is presumed that this edematous modification serves to flatten the egg mass for softness without crushing the eggs.

View full abstract

Larvae and juveniles of Lateolabrax japonicus and L. latus occurred from January to May 1986 in the shallow waters of the Shimanto estuary. L. japonicus markedly outnumbered L. latus. Distinct ecological differences were recognized in habitats and food habits between the two species: L. japonicus mainly inhabited eelgrass beds composed of Zostera nana, while L. latusappeared evenly in both eelgrass beds and non-eelgrass habitats; the former fed on copepods and cladocerans, while the latter fed on copepods and fish larvae. From these habitat and food habit analyses, estuaries were considered to be important as a main habitat for L. japonicus, but not for L. latus. The fact that ecological differences have occurred during the early life stages was inferred to be one of the possible keys to speculate on the speciation of the two species.

View full abstract

Larval development of Odontobutis obscura obscura, reared with Artemia sp.and Limnodrilus sp.for about two months, was observed in a room maintained at 20±0.5°C. The development was classified into nine nominal stages, and was compared with that of O. o. interrupta and of O. platycephala. The size and shape of the eggs and the development of this species are similar to those of O. o. interrupta and O. platycephala. From the juvenile stage, O. obscura is distinguishable from O. platycephala by the appearance of dark bands on the body located in the same position as in adults. O. o. interrupta is also distinguished from O. o. obscura in the juvenile stage by the presence of melanophores on the dorsal and ventral sides of the caudal peduncle. The anal fin fold of O. obscura is higher than the dorsal fin fold, but the two folds are equal in height in O. platycephala. O. obscura has a well-developed air bladder and swims high in the water at the feeding stage. O. platycephala has a poorly developed air bladder and swims on the bottom. Xanthophores are observed at an earlier stage and more strongly developed in O. obscura than in O. platycephala. Growth rate is faster in O. obscura than in O. platycephala. O. obscura spawns at a smaller body size than O. platycephala. In O. o. obscura, the arrangement of cephalic pit organs is completed at 14mm SL. In O. o. interrupta, this arrangement is completed at the same time or a little later than in O. o. obscura. The infraorbital and verticalantorbital pit lines of O. platycephala, which are separated in the adults, are connected until the juveniles measure about 30mm SL. These pit lines are connected even in the adults of O. o. obscura and interrupta. In O. platycephala, the sensory canals are first formed behind the eyes, then dorso-anterior to the eyes, then at the posterior edge of the preopercles and finally anterior to the eyes. Postocular canals begin to form in individuals more than 20mm SL. All individuals of O. o. interrupta more than 70mm SL have postocular canals. O. o. obscura has no sensory canals throughout life. The differences in growth rate, body size at spawning, and the time of completion of the cephalic lateral line system suggest paedomorphosis in the three taxa studied here.

View full abstract

A total of 7, 000 larval and juvenile Plecoglossus altivelis was collected at semimonthly intervals with a small seine in a surf zone of Tei beach facing Tosa Bay during the period of June 1982 to May 1983. They occurred in the surf zone from middle October to middle May. About 500 larvae and juveniles (10.9-59.9 mm TL) were used to examine their feeding habit. The feeding incidences by collection dates fluctuated from 0 to 100%, with 90.6% in total incidence. They fed mainly on copepods (e.g. Paracalanus parvus and Oithona spp.) throughout postlarval and juvenile stages, while they first took small benthic animals at 53.0mm TL. Their food compositions were influenced fundamentally by the planktonic fauna of the surf zone, but larvae under 20mm TL tended to take relatively larger copepods.

View full abstract

Catlocarpio siamensis Boulenger is a gigantic cyprinid of the subfamily Barbinae occurring in the Menam Chao Phrya River in Thailand and the Mekong River systems in Laos, Cambodia and Vietnam. Due to its morphological resemblance to the Indian and Burmese Catla catla (Hamilton-Buchanan), this species has often been assigned to the genus Catla or even identified as Catla catla (or its synonym, Catla buchanani).
Karyologically, Catla catla is known to be a diploid species with a diploid chromosome number of 50 (Manna and Khuda-Bukhsh, 1977), but the chromosomes of Catlocarpio siamensis have not been studied. In the present study, we found that Catlocarpio siamensis has a diploid chromosome number of 98 and most probably there is a diploid-tetraploid relationship between the two species.

View full abstract

It is known that Lamprologus attenuatus is a substratum spawner and its offsprings are guarded by both parents, or rarely, the female parent on a sandy area in Lake Tanganyika (Kuwamura, 1986). However, details of growth of larvae under parental care are unknown.
Growth of larvae under parental care has been studied on Tanganyikan cichlid fishes (Yanagisawa and Nshombo, 1983; Nagoshi, 1985; Yanagisawa, 1986, 1987). Nagoshi (1985) suggested that in the genus Lamprologus the growth of larvae under parental care is related to the mode of parental care and microdistribution of the larvae in the breeding territory.
In the present study, the growth of larvae under parental care in L. attenuatus was described on the basis of underwater field observations. The characteristics of the larval growth of this species were discussed in comparison with the growth of other Lamprologus species.

View full abstract