Pelagic eggs and larvae of Coryphaenoides marginatus (Gadiformes: Macrouridae) collected from Suruga Bay, Japan

The pelagic eggs, yolk-sac and pelagic larvae of the macrourid fish, Coryphaenoides marginatus, from Suruga Bay in southern Japan, are described. The identification of the pelagic eggs based on 16S rRNA gene nucleotide sequences agreed with that obtained from morphological analyses. The spherical eggs, 1.14–1.30 mm in diameter, contained a single oil globule 0.30–0.38 mm in diameter, and had hexagonally patterned ornamentation on the chorion, 0.025–0.033 mm in width. Many melanophores were present on the anterodorsal region of the embryo after the caudal end had detached from the yolk. Within a day after hatching, each of the yolk-sac larvae had a body axis that was bent slightly at the anterior trunk region, many dorsal and lateral melanophores on the trunk plus several on the gut, and small irregular wrinkles on the dorsal and anal fin membranes. The pelagic larvae had a short caudal region in comparison to other known congeners (length 2.0–3.2+ times head length vs. 4–7, respectively), a short stalked pectoral fin base, and no elongate first dorsal and pelvic fin rays. They were further characterized by the presence of numerous very dense melanophores from just behind the eye to the anterior part of the caudal region at 5.1 mm head length (25.8+ mm total length). The significant difference in vertical distribution between the pelagic eggs and larvae (dominant depths ca. 200–350 m vs. ca. 10–100 m, respectively), with no subsequent collection of pelagic larvae with greater than 6 mm head length, indicate two stages (rising and falling) of ontogenic vertical migration.     

Larvae of <Emphasis Type="Italic">Lamprogrammus shcherbachevi</Emphasis> (Ophidiiformes: Ophidiidae) from the western North Pacific Ocean

Three exterilium larvae (18.2 mm notochord length to 113.3 mm standard length) of an ophidiid, Lamprogrammus shcherbachevi, from the western North Pacific are described. The specimens had a highly specialized morph with a remarkably elongate trailing gut and ventral coracoid process, and many elongate anterior dorsal fin rays, as occur in other exterilium larvae, but were characterized by unique melanophore patterns (a cluster of melanophores on the back of the stalked pectoral fin base, a row of clusters midlaterally on the trunk and caudal region, and further clusters on the trailing gut). Although the largest specimen (113.3 mm standard length, much larger than the previously recorded maximum size of exterilium larvae) retained typical features of the exterilium stage, the ventral coracoid process was significantly reduced in size compared with that of a smaller specimen (37.8 mm standard length). Comparison of the largest specimen with an adult suggests that the anterior dorsal fin rays would disappear during the transformation stage.     

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.     

Larval and juvenile Polymetme elongata (Stomiiformes: Phosichthyidae) collected from Suruga Bay and offshore waters, Japan

Two larvae [17.4 mm standard length: SL (postflexion stage)] and 26.1 mm SL (transformation stage)] and a juvenile (31.7 mm SL) of a phosichthyid, Polymetme elongata, from Suruga Bay and offshore waters, central Japan, are described. These specimens had an elongate body with relatively short preanal length (53–63% SL), long anal fin base (2.6–3.4 times dorsal fin base length), and anal fin origin below dorsal fin base, and were further characterized by a blackish flap on each eye and internal clusters of melanophores (e.g., along caudal myosepta around midlateral line and on ventral margin of caudal peduncle). The short preanal length and larval melanophore pattern were very similar to those of another phosichthyid, Yarrella blackfordi, from the Atlantic Ocean.     

Development of eggs, larvae and juveniles of laboratory-reared blue whiting,Sillago parvisquamis (Percoidei: Sillaginidae)

The embryonic, larval and juvenile development of blue whiting,Sillago parvisquamis Gill, are described from a series of laboratory-reared specimens. Mean egg diameter and mean total length (TL) of newly-hatched larvae were 0.71 mm and 1.58 mm, respectively. The eggs were non-adhesive, buoyant and spherical with an oil globule (mean diameter 0.18 mm). Hatching occurred about 20 hours after fertilization at a temperature of 24.0–25.0°C, newly-hatched larvae having 38–40 myomeres. The yolk and oil globule were completely absorbed 3 days after hatching at 2.8–3.2 (mean 3.0) mm TL. Notochord flexion was completed by 7.2–8.2 (7.7) mm TL, and pectoral and caudal fin rays fully developed by approximately 10 mm and 8.5 mm TL, respectively. Completion of fin development occurred in the following sequence: caudal, pectoral, anal and second dorsal, first dorsal and pelvic, the last-mentioned by approximately 11 mm TL. The larvae ofS. parvisquamis andS. japonica, which closely resemble each other in general morphology and pigmentation, could be distinguished as follows. Newly-hatchedS. parvisquamis larvae had more myomeres thanS. japonica (38–40 vs. 32–34) and more melanophores on the dorsal surface of the body (19–28 vs. about 40).Sillago japonica had a vertical band of melanophores on the caudal peduncle, which was lacking in postflexionS. parvisquamis larvae. In addition, juveniles ofS. parvisquamis (larger than 23 mm TL) had melanophores on the body extending anteriorly to below the lateral line to form a midlateral band, whereas no obvious band occurred on similarly-sizedS. japonica juveniles.     

Pelagic eggs and larvae of Coelorinchus kishinouyei (Gadiformes: Macrouridae) collected from Suruga Bay, Japan

Pelagic eggs and larvae of the macrourid fish Coelorinchus kishinouyei, collected from Suruga Bay, southern Japan and subsequently identified by 16S rRNA gene nucleotide sequences, are described. The spherical eggs, 1.18–1.31 mm in diameter, contained a single oil globule, 0.28–0.33 mm in diameter, and had hexagonally patterned ornamentation on the chorion, 0.017–0.022 mm in width. Melanophores were present on the embryo, yolk and oil globule after the blastopore had closed. Within 1 day after hatching, the body axis of the yolk-sac larvae was bent slightly at the anterior trunk region. During this stage many melanophores formed on the head, trunk, tail, yolk and oil globule, along with small irregular wrinkles on the dorsal and ventral finfolds. Pelagic eggs (after the caudal end of the embryo had detached from the yolk) and yolk-sac larvae also developed xanthophores on the embryo and yolk, and head, trunk, dorsal and ventral finfolds just before tail tip, and yolk, respectively. The pelagic larvae had a short tail, stalked pectoral-fin base and no elongate first dorsal and pelvic-fin rays. Three clusters of melanophores were present on the tail (anterior two embedded to muscle and one just before tail tip subsequently lost with development) and a cluster around the anus (beyond 3.9 mm head length). Nucleotide sequence analyses of comparative adult specimens appeared to confirm a previous proposal that C. productus is a junior synonym of C. anatirostris.     

Developmental morphology of the cyprinid fish Tanichthys albonubes

Embryonic, larval, and juvenile development of a small cyprinid species, Tanichthys albonubes, is described from laboratory-reared specimens. The eggs, measuring 1.0–1.2 mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yolk without oil globules. Hatching occurred 45–53 h after fertilization at 25.5°–26.9°C. The newly hatched larvae, measuring 2.2–2.6 mm in body length (BL), had melanophores on the head and body. In particular, a dark vertical streak occurring posterior to the otic capsule and melanophores above the eyes were distinctive. The yolk was completely absorbed at 3.4 mm BL. Notochord flexion was initiated at 5.0 mm BL and finished at 6.0 mm BL. Aggregate numbers of all fin rays were completed at 11 mm BL. Squamation was initiated at 8.4 mm BL and completed at 13 mm BL. Although the eggs of T. albonubes resembled those of other small danionin species, including Aphyocypris chinensis, Chela dadiburjori, Danio rerio, Devario malabaricus, Gobiocypris rarus, Hemigrammocypris rasborella, and Horadandia atukorali, they differed from those of A. chinensis, C. dadiburjori, G. rarus, and Horadandia atukorali in having a wider perivitelline space. The larvae and juveniles of T. albonubes were similar to those of the aforementioned seven species plus Danio albolineatus, Danio kerri, and Devario sp. (cf. D. aequipinnatus) in general morphology. However, the early life stage morphology of T. albonubes differed from them in having a dark vertical streak posterior to the otic capsule and melanophores above the eyes in the yolk sac larval stage, and a dark lateral streak with an unpigmented area just above the former on the body, a dark blotch on the caudal fin, and reddish dorsal, anal, and caudal fins during the postflexion larval and juvenile stages.     

Description and ecology of larvae and juveniles of three native cypriniforms of coastal southern California

Larval series of the Santa Ana sucker, Catostomus santaanae (Federally Threatened), arroyo chub, Gila orcutti (California Species of Special Concern), and Santa Ana speckled dace, Rhinichthys osculus (California Species of Special Concern) are described from wild-caught specimens from the Los Angeles and Santa Ana river drainages. Santa Ana sucker larvae are elongate, having 41–46 myomeres and a distinctive paired-triangle patch of melanophores over the midbrain. Melanophores present on the snout, dorsal body, lateral midline, dorsal gut, postanal ventral body, and caudal fin. Preanal length 74–79% in body length (BL), typical of catostomids. Arroyo chub larvae relatively deep-bodied, 36–39 myomeres, and a heart-shaped patch of melanophores over the midbrain with a line of melanophores trailing posteriorly. Heavy pigment present on the snout, lower jaw, dorsal body, lateral midline, gill arches, dorsal gut, postanal ventral body, and caudal fin; short preanal length of 65–72% BL, typical of native North American cyprinids. Santa Ana speckled dace are similar to arroyo chub except for having less pigment on the ventral gut, large distinct melanophores on the ventrolateral caudal peduncle, a wedge-shaped patch of midbrain melanophores with no distinct line trailing posteriorly, and lateral midline melanophores that do not extend anteriorly. These three species often occur together and with nonnative cyprinids. Characters distinguishing them from other local larvae, including southern fathead minnow, Pimephales promelas confertus and red shiner, Cyprinella lutrensis, are discussed with their habitat preferences.     

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.     

Growth and morphological development of larval and juvenileepinephelus bruneus (perciformes: Serranidae)

The growth and morphological development of larval and juvenileEpinephelus bruneus were examined in a hatchery-reared series. Average body length (BL) of newly-hatched larvae was 1.99 mm, the larvae growing to an average of 3.96 mm by day 10, 6.97 mm by day 20, 12.8 mm by day 30, 22.1 mm by day 40 and 24.7 mm by day 45 after hatching. Newly-hatched larvae had many mucous cells in the entire body epidermis. By about 4 mm BL, the larvae had developed pigment patterns peculiar to epinepheline fishes, including melanophores on the dorsal part of the gut, on the tips of the second dorsal and pelvic fin spines, and in a cluster on the ventral surface of the tail. Spinelets on the second dorsal and pelvic fin spines, the preopercular angle spine and the supraocular spine, had started to develop by about 6 mm BL. The notochord tip was in the process of flexion in larvae of 6–8 mm BL, by which time major spines, pigments and jaw teeth had started to appear. Fin ray counts had attained the adult complement at 10 mm BL. After larvae reached 17 mm BL, elements of juvenile coloration in the form of more or less densely-pigmented patches started to appear on the body. Squamation started at 20 mm BL. Major head spines had disappeared or became relatively smaller and lost their serrations by 20–25 mm BL.     

A new miniature species of the genus Triplophysa (Balitoridae: Nemacheilinae) from Yunnan, China

During a re-examination of museum specimens of Triplophysa species, some specimens that had been collected from the Jialonghe River in Yunnan Province, China, in April 1975, were identified as a new species. Triplophysa parvus n. sp. can be distinguished by the following combination of characters: dorsal fin rays 3, ; anal fin rays 3, ; pectoral fin rays 1, 11; scales absent; two saddle-like blotches with fuzzy borders cranial to the dorsal fin and four saddle-like blotches caudal to the dorsal fin; distal margin of the dorsal fin emarginate; pelvic fin reaching caudally almost to the anus; anus located immediately cranial to the origin of the anal fin; caudal fin forked; caudal chamber of air bladder reduced to a small free protuberance; head slightly laterally compressed, head deeper than wide at nape; length of caudal peduncle being 18.0–20.0% of standard length; depth of caudal peduncle being 7.8–8.4% of standard length; eye diameter 17.6–21.4% of head length; body depth being 60.7–70.2% of head length; caudal peduncle depth being 39.1–45.0% of caudal peduncle length; and body width at the base of caudal peduncle 59.0–68.0% of the body depth at the base of caudal peduncle. These characters allow a distinction from the similar species of T. nasobarbatula, T. nandanensis, and T. macromaculata.     

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.     

Embryonic and early larval development of <Emphasis Type="Italic">Cottus czerskii</Emphasis> Berg, 1913 (Scorpaeniformes: Cottidae)

The embryonic and early larval development of the Cherskii’s sculpin Cottus czerskii Berg, 1913 was studied. The duration of the embryonic period was 21 days at a water temperature of 9–10°C. Pelagic larvae of approximately 8.0 mm total length leave the egg envelopes, with a large rounded yolk sac with one large oil globule, 10–12 trunk and 30–31 precaudal myomeres and several large melanophores on the yolk sac, 2 melanophores in the peritoneal region, and 30 melanophores in a postanal ventral row. At 11 days after hatching at a length of 9.0 mm, the yolk sac is completely resorbed and the number of myomeres remains the same; seven rays become visible in the caudal fin. The fully formed larva of C. czerskii has an elongated body, a small head, a rounded snout, and an oblong tail part. The melanophores are located in the peritoneal area above the gut, in the abdominal area, and in the postanal ventral row. Armament in the form of spines on the top of the head is absent, pointing to the affiliation of the species that we studied to the Cottus–Leptocottus phenetic group.     

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.     

Larval development of Asemichthys taylori (Cottidae)

Larvae of Asemichthys taylori were reared in the laboratory to identifiable juveniles. A preserved series of larvae was characterized in part by fin meristics (X–XI, 14–15 dorsal fin rays; 15 anal fin rays), as well as a combination of the alignment of the jaw tip with the ventral margin of the gut, heavy lateral melanistic pigment except on the caudal peduncle, and a series of postanal ventral melanophores. An internal, horizontal band of melanin extends through the head from the snout to the gut. Hypural plates do not align vertically even after settlement, giving the appearance that the larvae do not complete notochord flexion during their planktonic stage. Larval A. taylori resemble known larvae of Radulinus spp., a genus under which some authors have synonymized the monotypic genus Asemichthys.     

Leptocephalus larvae of Pterothrissus gissu collected from the Kuroshio–Oyashio transition region of the western North Pacific, with comments on its metamorphosis

 Pterothrissus gissu is a rare albulid fish that is distributed in deep water off Japan. This fish is known to pass through a leptocephalus larval stage, but only metamorphosed (after reaching the fully grown stage) specimens have been available. In this study, the premetamorphosis (before fully grown stage) leptocephalus larva of P. gissu is first described from 45 specimens (117.2–194.5 mm SL) collected by a pelagic otter trawl in the Kuroshio–Oyashio transition region of the western North Pacific in May 1995. Premetamorphosis leptocephalus larvae are characterized by having poorly developed fin rays except for the caudal fin, a translucent body, branched melanophores beneath the eye, and punctuate melanophores on the dorsal edge of the gut from the throat to the anus. Previously fully grown leptocephali were estimated to reach about 130 mm SL based on the size distributions of metamorphosing specimens. However, the present specimens show that fully grown leptocephali of P. gissu exceed 180 mm SL. Received: March 21, 2001 / Revised: March 19, 2002 / Accepted: April 15, 2002     

A description of the smallest Triodon on record (Teleostei: Tetraodontiformes: Triodontidae)

The smallest known specimen (20mm standard length: SL) of Triodon macropterus Lesson is described and illustrated. It is easily distinguished from superficially similar tetraodontid and diodontid larvae or early juveniles of comparable size by the following characters: separate premaxillae in conjunction with the fused dentaries; the presence of multicuspid spinoid scales; the jet-black mark in front of the soft dorsal fin; the developing pelvis, which is visible through the distended skin of the belly; and the presence of a number of procurrent caudal fin rays. The small Triodon differs from the adult in possessing a huge head that measures 45% SL (vs. 28.5–32.7% in adult), the absence of the characteristic dewlap with the conspicuous lateral ocellus, and the structure of the scales and nostrils.     

An unusual macrourid larva (Gadiformes) from San Juan Island, Washington, USA

An unusual macrourid larva was collected in Friday Harbor, San Juan Island, Washington, USA. This specimen is remarkable in appearance having very long anterior dorsal- and pelvic-fin rays, with flattened distal ends free of the fin membrane, and a long, whiplike, heavily pigmented caudal filament. It is similar to smaller Coryphaenoides pectoralis larvae reported from the California Current region, and different from larger specimens of C. pectoralis from the northern North Pacific. Counts and other morphological similarities suggest that this larva should be tentatively assigned to genus Coryphaenoides.     

Larval development of Pseudorhombus oculocirris and P. arsius (Pleuronectiformes, Paralichthyidae) from off southern Japan

 Larvae of two paralichthyids, Pseudorhombus oculocirris and P. arsius, are described and illustrated from specimens collected off Tosa Bay, southern Japan. Peudorhombus oculocirris larvae (5 specimens, 4.5–7.8 mm BL) are characteristic in having 6 or 7 elongated anterior dorsal fin rays and poorly developed head spines and melanophores on the tail. Pseudorhombus arsius larvae (3 specimens, 5.3–8.4 mm BL) are distinctive in having 11 or 12 elongated anterior dorsal fin rays and well-developed head spines, including a row of spines on the sphenotic. Received: June 28, 2001 / Revised: November 2, 2001 / Accepted: November 22, 2001