Morphogenesis in hatchery-reared larvae of the black rockfish,Sebastes schlegeli,and its relationship to the development of swimming and feeding functions

The developmental sequence of morphological characteristics related to swimming and feeding functions was investigated in hatchery-reared larvae and juveniles ofSebastes schlegeli, a viviparous scorpaenid. The fish were extruded at an early larval stage, when the mean body size was 6.23 mm TL. Fin-ray rudiments became visible at 9.0 mm TL in the dorsal and anal fins, at 8.0 mm TL in the pectoral and pelvic fins and 6.0 mm TL (size at extrusion) in the caudal fin. Completion of segmentation of soft rays in the dorsal and anal fins was attained by 14 mm TL and in all fins by 17 mm TL. Branching of soft rays in the respective fins started and was completed considerably later than the completion of segmentation, as well as ossification of the fin-supports. Morphological transformation from larva to juvenile was apparently completed by about 17 mm TL. Although the completion of basic juvenile structures was attained by transformation at that body size, succeeding morphological changes occurred between 17 mm and 32 mm TL. Newly-extruded larvae possessed one or two teeth on the lower pharyngeal and pharyngobranchials 3 and 4, but lacked premaxillary, dentary, palatine and prevomer teeth. The fish attained full development of gill rakers and gill teeth by 15 mm TL, the upper and lower pharyngeal teeth subsequently developing into a toothplate. Development of the premaxillary, dentary and palatine teeth was completed at about 30 mm TL, by which time loop formation of the digestive canal and the number of pyloric caeca had attained the adult condition. The developmental sequence of swimming and feeding functions during larval and early juvenile periods appeared to proceed from primitive functions to advanced or complex ones, from the ability to produce propulsive force to that of swimming with high maneuverability and from development of the irreducible minimum function of passing food into the stomach to the ability to actively capture prey via passive food acquisition with the gill rakers and gill teeth. The relationship of morphological development to the behavior and feeding activity of artificially-produced hatchlings is also discussed.     

Larval development of Argentine hake Merluccius hubbsi

The ontogeny of the developmental stages of the hake Merluccius hubbsi is described. Fish larvae and post-transitional juveniles were collected in the Nor-Patagonian area from 1989 to 2004. The opening of the mouth and the pigmentation of the eyes are coincident with yolk resorption, finishing the yolk-sac stage. This species presents pigmentation on the head, trunk and tail typical of gadiform larvae. Pectoral fin development is completed during the transformation stage. The post-transitional juvenile stage begins when the fin-ray complements are complete and squamation begins. The fins become fully formed in the following sequence: pelvic fins, first dorsal fin, second dorsal and anal fins together, caudal fin and pectoral fins. The caudal complex is totally developed in larvae of 22·0–23·0 mm standard lengths ( L _S) and all vertebral elements are first observed in larvae of 8·5 mm L _S. The rate of development of M. hubbsi observed in this study could be faster than the rates reported for other species of Merluccius by different authors.     

Skeletal development and abnormalities of the vertebral column and of the fins in hatchery-reared turbot Scophthalmus maximus

To describe the skeletal development and abnormalities in turbot Scophthalmus maximus, samples were collected every day from hatching to 60 days after hatching (DAH). A whole-mount cartilage and bone-staining technique was used. Vertebral ontogeny started with the formation of anterior haemal arches at 5·1 mm standard length (L(S) ) c. 11 DAH, and was completed by the full attainment of parapophyses at 16·9 mm L(S) c. 31 DAH. Vertebral centra started to develop at 6·3 mm L(S) c. 16 DAH and ossification in all centra was visible at 11·0 mm L(S) c. 25 DAH. The caudal fin appeared at 5·1 mm L(S) c. 11 DAH and ossification was visible at 20·6 mm L(S) c. 37 DAH. The onset of dorsal and anal fin elements appeared at 5·8 mm L(S) c. 15 DAH and 6·3 mm L(S) c. 16 DAH, respectively. Ossifications of both dorsal fin and anal fin were visible at 20·6 mm L(S) c. 37 DAH. The pectorals were the only fins present before first feeding, their ossifications were completed at 23·5 mm L(S) c. 48 DAH. Pelvic fins began forming at 7·2 mm L(S) c. 19 DAH and calcification of the whole structure was visible at 19·8 mm L(S) c. 36 DAH. In the present study, 24 types of skeletal abnormalities were observed. About 51% of individuals presented skeletal abnormalities, and the highest occurrence was found in the haemal region of the vertebral column. As for each developmental stage, the most common abnormalities were in the dorsal fin during early metamorphic period (stage 2), vertebral fusion during climax metamorphosis (stage 3) and caudal fin abnormality during both late-metamorphic period (stage 4) and post-metamorphic period (stage 5). Such research will be useful for early detection of skeletal malformations during different growth periods of reared S. maximus.     

伊克昭弓鳍鱼在华南的发现

<正> 近年来,随着地层工作的深入,在华南中生代晚期地层中,接二连三地发现了与华北中生代晚期狼鳍鱼群中的鱼化石相近的种类。继华南中华弓鳍鱼(Sinamia huananensis,苏德造,1973)、伍氏副狼鳍鱼(Paralycoptera wui,张弥曼、周家健,1977)之后,浙江省区测队在缙云县壶镇水口晚侏罗世火山岩系的沉积夹层中,又发现了伊克昭弓鳍鱼(Ikechao-amia)。这一鱼化石和内蒙的东方伊克昭弓鳍鱼(I.orientalis Liu)有些不同,我们在此简单记述,并对伊克昭弓鳍鱼属的特征作些补充,以期对我国南、北地区中生代晚期鱼群的综合研究提供些许资料。     

Larvae and juveniles of the plunderfishes <Emphasis Type="Italic">Artedidraco shackletoni</Emphasis> and <Emphasis Type="Italic">A.</Emphasis><Emphasis Type="Italic">skottsbergi</Emphasis> (Notothenioidei,Artedidraconidae) from the Indian sector of the Southern Ocean

Early life stages of Artedidraco skottsbergi and A. shackletoni were collected off Adélie Land. The morphology and pigmentation pattern of nine larvae and juveniles of A. skottsbergi between 17.2 and 21.4 mm in standard length (SL), and of two juveniles of A. shackletoni measuring 25.1 mm SL were described. A. skottsbergi was characterized by a heavily pigmented body, except for the caudal peduncle, with distinctively dense pigmentation on the ventrolateral half of the body and caudal section (17.2–17.9 mm SL). Furthermore, they had no pigmentation on the pectoral fin base until they attained 21.4 mm SL. Juvenile A. shackletoni had a heavily pigmented body except for the ventral side of the abdomen and the anal fin base. The proximal part of the dorsal fin and most of the anal fin were covered with melanophores. Although knowledge of larval and juvenile Artedidraco species is limited, the distribution of melanophores on the fins, pectoral fin base and caudal peduncle at each developmental stage may be useful for species identification.     

Osteological development of the lophiid anglerfish,lophius gastrophysus

The osteological development of the head skeleton and dorsal, pectoral, and anal fin supports, are described from cleared and stained specimens ofLophius gastrophysus larvae, ranging from 4.6 to 21.8 mm NL; the results are compared with those of juvenile (79.8 mm SL) and adult (398 mm SL) specimens. Tiny conical teeth are present on the premaxillary, dentary, palatine and vomer since early stage. The first three dorsal fin spines are initially positioned on the midline of body posterior to the supraoccipital, but they migrate forward with growth and become cephalic in juveniles. The forward movement of the dorsal spines is produced by the forward extension of the cartilaginous basal inside the subepidermal space. During the planktonic larval stage the pectoral fins are on the sides of body as in ordinary fishes, but they move ventrad and become leg-like in bottom living juveniles and adults. Ossification of the caudal complex ofL. gastrophysus larvae proceeds very slowly and only the 21.8 mm NL larva has an almost completely ossified caudal complex. Eight principal caudal rays are loosely attached on the posterior edge of the hypurals and no procurrent rays are present. Larvae have well developed parhypurapophysis at the mid-portion of the urostyle which transforms into keel-like structure in juveniles and adults.     

Fossil record of a silurid catfish from the Middle Miocene Sanuki Group of Ohkawa, Kagawa Prefecture, Japan

A fossil specimen identified as a silurid catfish (92.5 mm SL) was collected from the Middle Miocene Sanuki Group (15.8±0.9 Ma) of Ohkawa, Kagawa Prefecture, Japan. This is the oldest certain record of a silurid catfish. Morphological characteristics of the specimen are as follows: 52 or 53 vertebrae, 61 or 62 anal fin rays, a stout, short spine (11%SL) and 10 or more soft rays of the pectoral fin, 8 or more pelvic fin rays, 8 or more branchiostegal rays, head length of ca. 24%SL, and most probably not forked caudal fin. The fossil specimen is clearly distinct from three extant silurids in Japan, and probably belongs to an undescribed form considering its geological age.     

Reproduction and early development of a freshwater pipefish <Emphasis Type="Italic">Microphis leiaspis</Emphasis> in Okinawa-jima Island,Japan

We investigated the size at maturation, breeding season, and morphological development of larvae and juveniles of a freshwater pipefish Microphis leiaspis, which belongs to Gastrophori, collected from three rivers on the northern part of Okinawa-jima Island, Japan. The minimum size of brooding males was 105–123 mm in standard length (SL). The smallest mature female was estimated to be ca. 130 mm SL from the analysis of gonadosomatic index (GSI) and histological observations of gonads. The breeding season was estimated to be from June to December according to monthly changes in female GSI, histological observations of gonads, and monthly changes in the occurrence of brooding males. The number of eggs in the male brood pouch ranged from 75 to 241 (mean ± SD: 152 ± 52, n = 22). The male releases newly hatched larvae in freshwater areas. After newborns grow in the sea, they return to freshwater areas of the rivers and attain maturity. Microphis leiaspis was conformed to have an amphidromous life history. Notochord length of the released larvae was 6.1 mm, with a well-developed finfold. Larvae attained 11.1 mm SL, formation of the caudal and dorsal fin rays was complete, and the caudal fin became lozenge shaped at 30 days after the release, and juveniles reached 36.0 mm SL at 63 days after release. In the period between 30 and 63 days after the release, formation of all fins except the pectoral fins was completed, and caudal fin rays were extended and sector shaped with deep slits between each fin ray. The morphology of the released larvae of M. leiaspis is similar to that of Gastrophori species, and the morphology of juveniles similar to other species of Microphis.     

高原特有条鳅鱼类两新种在广西的发现及其动物地理学意义

描述了采自广西都安县红水河水系的条鳅亚科鱼类2个新种：丽纹云南鳅yhnnanilus pulcherrimussp．nov．在侧线长度、鳞片分布、鳍条数目、尾型、吻须长度等方面与侧纹云南鳅yunnanilus pleurotaenia(Regan,1904)最为相似,但新种独特的斑纹和上下唇的长乳突可明显与之区别,二者在一些度量特征上也有区别。黄体高原鳅Triplophysa flavicorpus sp．nov．与同分布于西江水系的南丹高原鳅T．nandanensis Lan et al．较为相似,并以下列特征组合与高原鳅属所有已知种相区别：背鳍分枝鳍条10根、臀鳍分枝鳍条6～7根、体被细鳞、侧线完全、具6条宽横斑和1条沿侧线的细纵纹、尾鳍深分又、尾鳍基具1半圆形黑斑、尾鳍上下叶各具2条黑色横斑、腹鳍末端后伸超过肛门、腋部具发达的肉质鳍瓣、上唇中央完全中断等。云南鳅属和高原鳅属均是高原特有类群,前者仅分布于云南东中部地区,后者则集中分布于青藏高原。两个新种的分布地均远离这两个属的分布中心,而且呈间断分布。通过各自相近种谱系关系分析,推测这种特殊的分布格局是通过隔域分化形成的。     

Developmental structure of the vertebral column,fins, scutes and scales in bester sturgeon,a hybrid of beluga Huso huso and sterlet Acipenser ruthenus

In the larval bester, a hybrid sturgeon of beluga Huso huso and sterlet Acipenser ruthenus, development of cartilage around the notochord began 7 days post hatch (dph) (14·0 mm, total length, L_T). The vertebral cartilage develops in the following sequence: basidorsals and basiventrals, neural canals, neural spines and ribs. The development of ribs remained incomplete in the largest specimen (181 dph, 179 mm L_T) that was examined. Endoskeletal development of the fins began 4 dph for the dorsal and anal fins, 6 dph for the pectoral fin and 10 dph for the caudal and pelvic fins. Complete elements of all fins were observed by 91 dph and complete ossification of fin rays was observed by 122 dph in the double‐stained specimens. Observation of the histological sections, however, suggested that ossification occurred soon after the formation of the organic matrix in the fin rays. Dorsal scutes were first visible by 25 dph, followed by the lateral and ventral scutes, which were visible by 37 and 44 dph, respectively. The number of scutes was fixed at 44, 59 and 91 dph and ossification was complete by 59 (dorsal) and 91 dph (lateral and ventral scutes) in the double‐stained specimens. Ossification occurred soon after the formation of the scute organic matrix in the histological sections. Four types of scales were observed in the H. huso×A. ruthenus hybrid. Median predorsal, preanal and small scales on the anterior section of the head were visible by 59 dph. Scales on the caudal fin were visible by 91 dph and a variable assemblage of scales anterior to the anal fin was visible by 122 dph. Both the scutes and scales developed in a process that is similar to that of intramembranous ossification.     

Osteological development in the Japanese sardine,Sardinops melanostictus

The development of all osteological elements, except scales, of the Japanese sardine,Sardinops melanostictus, is described from newly-hatched larvae to adult fishes. Newly-hatched larvae lacked osteological elements. Part of the head skeleton began to develop in 53 hour old larvae (4.2 mm in notochord length [NL]). Larvae at the first-feeding stage (77 hours, 5.5 mm NL) possessed several elements of the head skeleton and pectoral fin supports. In a 10.5 mm NL specimen, part of the caudal and dorsal fin supports were apparent. The centra appeared in specimens 18–22.7 mm in standard length (SL). Gill rakers were first observed in the lower branchial arches at 13 mm NL and spine-like processes with spiny nodules from about 25 mm SL. The distance between the predorsal and first dorsal proximal radial relative to SL rapidly decreased with forward translocation of the dorsal fin and became constant beyond approximately 34 mm SL. At this stage, most basic osteological elements were established. Completion of the osteological structure was characterized by the disappearance of the dentary teeth at 60–70 mm SL. Based on the osteological development, ontogenetic intervals consisting of four periods and eight phases were recognized.     

Juvenile development of a flathead,Suggrundus meerdervoortii (Scorpaeniformes: Platycephalidae)

Juvenile development ofSuggrundus meerdervoortii was described, based on twelve specimens (12.9–43.8 mm SL) collected from off Yamagata Prefecture, Japan Sea. Two exterior openings in the lateral line scales were completed at ca. 35 mm SL, with the interopercular flap and iris lappet being visible at ca. 44 mm SL, these all being useful taxonomic characters. In juveniles and additional young and adult specimens (ca. 70–191 mm SL), the proportions of head length, snout length, orbital diameter, caudal peduncle depth and caudal fin length decreased with growth; interorbital width decreased rapidly until ca. 70 mm SL, but more or less stabilised thereafter (70–191 mm SL).     

A larva of Coryphaenoides pectoralis (Gadiformes: Macrouridae) collected by deep-sea submersible from off Hokkaido, Japan

A late-stage larva of Coryphaenoides pectoralis was first observed in situ and subsequently collected by the deep-sea submersible “Shinkai 2000” from mesopelagic waters at a depth of 530 m off Hokkaido, Japan. The larva (14.5 mm in head length, 149+ mm in total length) has fan-like pectoral fins, elongate first dorsal fin, pelvic fin and tail, 10 first dorsal rays (including 2 pseudospines), and 7 pelvic fin rays, 6 branchiostegal rays, no light organ, anus just anterior to anal fin origin, 2 retia and gas glands, 14 abdominal vertebrae, and previously reported larval pigmentation. Counts of second dorsal and anal fin rays, and caudal vertebrae, are reported for the first time.     

Redescription of <Emphasis Type="Italic">Bregmaceros mcclellandi</Emphasis> Thompson, 1840 (Gadiformes: Bregmacerotidae)

 This study redescribes Bregmaceros mcclellandi Thompson, 1840, based on one specimen (74.4 mm SL) from the Bay of Bengal and 66 specimens (30.0–84.7 mm SL) from Mumbai (Bombay), India, because the type specimens have apparently been lost. The present specimens are characterized by having black dorsal, pectoral, and caudal fins and show the following morphology: caudal fin slightly forked; body chromatophores present mainly at the dorsal part; no scales on cheek; vertebrae 52–55 (13–15 + 38–41); dorsal rays 52–59; anal rays 54–60; pectoral rays 18–20; caudal rays 27–31 (principal rays 14); transverse scales 14–15. In the 66 Mumbai specimens, it was confirmed that the distinctive black fin pigmentation developed sequentially with growth, with complete pigmentation first on the anterior lobe of the dorsal fin, then simultaneously on the posterior lobe of the dorsal fin, the caudal fin, and the pectoral fin, and last, on the anal fin. This species is known only from the Arabian Sea, Bay of Bengal, and Gulf of Thailand. A review of 16 nominal Bregmaceros species indicates that, besides B. mcclellandi, the distinctive dark fin pigmentation is found in B. atripinnis (Tickell), B. atlanticus Goode and Bean, B. japonicus Tanaka, and B. lanceolatus Shen. B. atripinnis is considered a junior synonym of B. mcclellandi, and the others are clearly distinct from B. mcclellandi. Comments are made on some of the characters to more fully characterize the species and for reference in future revisionary and phylogenetic studies. Received: June 17, 2002 / Revised: December 2, 2002 / Accepted: December 24, 2002     

Juveniles of two sillaginids,Sillago aeolus andS. sihama,occurring in a surf zone in the Philippines

Sillaginid juveniles collected from the surf zone at Tigbauan, Iloilo, Philippines, between May 1986 and September 1987 were identified asSillago aeolus (n=702, 8.9–26.0 mm SL) andS. sihama (n=3414, 8.6–22.9 mm SL), based on the numbers of dorsal and anal soft fin rays and vertebrae. The two species were easily distinguishable by the pattern of melanophores distributed on the caudal fin base,S. aeolus having a triangular-shaped cluster, whereas the melanophores formed a vertical line inS. sihama. The ratios of pre-anal and caudal peduncle lengths to SL also differed between the species, both being higher inS. aeolus. The occurrence ofS. aeolus was limited to the dry season, from January to March. On the other hand,S. sihama occurred year-round, although a peak was observed in the dry season, from November to April.     

REVIEW ON PEIPIAOSTEUS BASED ON NEW MATERIALS OF P. PANI

<正>Based on abundant new materials of Peipiaosteus pani, many features are newly described, they include: rostral bones, circumorbital series, the ectopterygoid process of the maxilla, quadratojugals, branchial toothplates, axial skeleton, fulcra and epiaxial fin-rays on the caudal fin. A few other features such as the hyomandibula and branchiostegal are revised. The ontogenetic and taphonomic characters of Peipiaosteus indicate that it probably assumed a habit of migration like its extant descendants. A review of the differences between P. pani and P. fengnengensis shows that all the differences except the dorsal and anal fin-ray numbers proposed by Bai (1983) are not true or remain uncertain. Through comparison, stichopterus is included in the revised family: Peipiaosteidae. Finally, a review of the phylogeny of Acipenseriformes results in a conclusion of Peipiaosteidae and Acipenseridae as sister groups.     

内蒙古石拐群古鳕类一新属

内蒙古石拐地区石拐群召沟组中的长腹鳍大青山鳕(新属、新种) Daqingshaniscus longiventralis gen. et sp. nov. 是在我国中侏罗世地层中发现的一比较原始的古鳕类.其头骨眶后部分短,鳃盖骨大于下鳃盖骨,背鳍位于腹鳍与臀鳍之间,腹鳍基线长,鳍条都从基部分节、远端分叉,棘鳞仅见于尾上叶,全歪型尾,鳞片呈菱形.大青山鳕既与苏联南哈萨克斯坦 Karatau 地区的 Pteroniscus 很接近,又与我国新疆的维吾尔鳕 Uighuroniscus 及西德北部的 Stadthagen 地区的 Indaginilepis 相似.     

Atrosalarias hosokawai, a new species of blenny (perciformes: Blenniidae) from the western pacific

A new species of blenny,Atrosalarias hosokawai is described on the basis of 15 specimens from the western Pacific. It is distinguished from the only known congeneric species,A. fuscus (=A. fuscus fuscus+A. fuscus holomelas), by the following: supraorbital cirrus broad and flat (vs. slender and thread-like inA. fuscus); dorsal fin broadly contacting caudal fin (vs. narrow contact); anal fin narrowly contacting caudal fin (vs. usually free or (rarely) very narrow contact); posteriormost dorsal and anal fin rays long (vs. short); first or posteriormost soft dorsal fin ray shortest (vs. posteriormost ray shortest); first soft anal fin ray shortest (vs. posteriormost ray shortest); caudal fin rays branched in specimens over 36.0 mm SL (vs. unbranched); a large dark spot on base of pectoral fin absent (vs. present or absent); a red margin on anterior dorsal fin absent (vs. present). Futhermore,A. hosokawai differs fromA. f. fuscus in having a lower number of dorsal fin spines (ten vs. eleven) and geographical distribution (western Pacific Ocean vs. Indian Ocean and Red Sea). AlthoughA. hosokawai occurs sympatrically withA. f. holomelas, it can be further distinguished from the latter in lacking a large dark spot on base of pectoral fin.     

Larval development of Hypsophrys nicaraguensis (Pisces: Cichlidae) under laboratory conditions

The cichlid Hypsophrys nicaraguensis is a popular fish known as butterfly, and despite its widespread use as pets, little is known about its reproductive biology. In order to contribute to this knowledge, the study describes the relevant larval development characteristics, from adult and larval cultures in captivity. Every 12h, samples of larvae were collected and observed under the microscope for larval stage development, and every 24h morphometric measurements were taken. Observations showed that at 120h, some larvae had swimming activity and the pectoral fins development was visible; at 144h, the dorsal fin appear and all larvae started food intake; at 168h, the formation of anal fins begins, small rudiments of pelvic fins emerge, the separation of caudal fin from anal and dorsal fins starts, and the yolk sac is reabsorbed almost completely; at 288h, the pelvic fins starts to form; at 432h, the rays and spines of dorsal and anal fins can be distinguished, both the anal and the dorsal fins have the same number of spines and rays as in adults. After 480h larvae have the first scales, ending the larval stages and starting the transformation to fingerlings. Larvae were successfully fed with commercial diet.