Lessons from the first dorsal fin in atheriniforms—A new mode of dorsal fin development and its phylogenetic implications

The median fins in extant actinopterygians are the product of millions of years of evolution. During this time, different developmental patterns for the dorsal and anal fins emerged leading to a high variation in median fin morphology and ontogeny. In this study, the development of anal and dorsal fins in atheriniforms is described and its consequences for the current phylogenetic hypothesis are discussed. Developmental series of five atheriniform species were investigated using clearing and staining as well as antibody staining. The skeletal elements of the second dorsal fin and the anal fin emerge in a bidirectional pattern. The first dorsal fin, however, arises separately in front of the second dorsal fin after this one is almost completely formed. The pterygiophores of the first dorsal fin, including the interdorsal pterygiophores, develop from caudal to rostral, but the fin‐spines of the first dorsal fin form in the opposite direction. This new mode of fin development has been found in all examined atheriniform species with two dorsal fins. Several morphological characters of atheriniforms, including interdorsal pterygiophores, are also found in one other taxon: the Mugiliformes. Thus, several dorsal fin characteristics may provide evidence for a closer relationship of these two taxa.     

Early morphological development ofOmobranchus fasciolatoceps andO. Punctatus (Blenniidae: Omobranchini) reared in an aquarium

Larval and juvenile development of two blenniids,Omobranchus fasciolatocepts andO. punctatus, is described using eggs collected from natural waters in Tokyo Bay and incubated in an aquarium. These larvae and juveniles are compared with those of two otherOmobranchus species,O. elegans andO. loxozonus, distributed widely in Japan.Onobranchus punctatus is characterized by a unique, pointed snout in preflexion larvae, no melanophores proximally on the lower part of the pectoral fins in flexion and postflexion larvae, and pterygiophores projecting externally as blades between the dorsal and anal fin-rays in postflexion larvae and juveniles.Omobranchus fasciolatoceps has the following characteristics: a few melanophores on the fore-and mid-brain, but none on the hind-brain in preflexion larvae; no melanophores on the cleithral symphysis in flexion and postflexion larvae; no external pterygiophore blades in postflexion larvae and juveniles; and a unique dorsal skin flap on the head in juveniles. Ontogenetic developement of dorsal and anal pterygiophores is described forO. fasciolatoceps andO. punctatus. InO. punctatus, the postero-distal part of each proximal radial projects remarkably to form the external blades between the soft fin-rays, whereas the external blades between the fin spines are formed by fusion of a dermal bone developed from the antero-distal part of each proximal radial with the adjacent distal radial.     

The Leiognathus splendens complex (Perciformes: Leiognathidae) with the description of a new species, Leiognathus kupanensis Kimura and Peristiwady

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes the Leiognathus splendens complex comprising four valid species: L. jonesi James, 1971, widely distributed in the Indo-West Pacific, from Mauritius to Papua New Guinea, north to Hainan I. (China), and south to Brisbane, Australia; L. kupanensis sp. nov., currently known only from Kupang, Timor, Indonesia; L. rapsoni Munro, 1964, currently known only from India, Indonesia, and Papua New Guinea, and L. splendens Cuvier, 1829, widely distributed in the eastern Indian and western Pacific oceans, from India to Papua New Guinea, and from southern Japan to northern Australia. The L. splendens complex can be defined by the following combination of characters: body depth 42–60% of standard length; mouth protruding downward; slender, minute teeth uniserially on jaws; lower margin of orbit above the horizontal through the gape when mouth closed; breast almost completely scaled; lateral line complete, and a dark blotch on top of spinous dorsal fin. Diagnostic characters of the members are as follows: L. jonesi—anterior dorsolateral body surface with a semicircular naked area on nape, and a paler dark blotch on spinous dorsal fin; L. kupanensis—anterior dorsolateral body surface widely naked; L. rapsoni—cheek scaled; L. splendens—anterior dorsolateral body surface completely scaled and a jet black blotch on spinous dorsal fin.     

Echinogobius hayashii, A new genus and species of gobiidae

Echinogobius hayashii, a new genus and species of Gobiidae is described, based on 11 specimens from Japan and Australia. This genus is distinguishable from all other gobiid genera in having the following combination of characters: first spine of first dorsal fin hard and straight, about 1.5 times second spine in thickness; first spine of second dorsal fin hard, with similar thickness as first soft ray of second dorsal fin, supported by two normally-sized pterygiophores; snout convex; preopercular spine absent; predorsal scales absent; all scales cycloid. The species occurs between 1–20 m in clear water on clear sandy bottoms influenced by fast tidal currents. Based on our observations, it is not associated with an alpheid shrimp.     

Larvae of two pleuronectiforms, Poecilopsetta plinthus (Poecilopsettidae) and Parabothus coarctatus (Bothidae), from southern Japan

Pelagic larvae of two pleuronectiforms, Poecilopsetta plinthus (Poecilopsettidae) and Parabothus coarctatus (Bothidae), are described and illustrated based on specimens collected off Tosa Bay, southern Japan. Postflexion larvae (8.2–11.9 mm BL) of Poecilopsetta plinthus are characteristic in having a series of melanophore patches along the dorsal and anal fin bases and the inner margins of the pterygiophore zones, and linear myoseptal pigmentation also along the inner margins of the latter. Preflexion and flexion larvae (5.0–6.3 mm BL) of Parabothus coarctatus are distinctive in having the dorsal fin origin located level with the dorsal margin of the eye and seven elongated rays in the anterior part of that fin. Received: November 18, 2000 / Revised: May 1, 2001 / Accepted: June 13, 2001     

Development of eggs of Antarctic krillEuphausia superba in relation to pressure

Summary This paper focuses upon the influence of increasing hydrostatic pressure on the development of krill eggs at 2°C. This experimental study on the embryology ofEuphausia superba was conducted at the Palmer Station, Antarctica during the 1982–1983 austral summer. The gravid females were captured from Bransfield Strait aboard theR/V Hero. The various embryological stages such as early cleavage, blastula, gastrula and limb-bud nauplius larva were defined and described. The duration for these various developmental stages at 1 atm was also established at +2°C and compared with the timing of this event at negative temperature. Krill embryonic development is inhibited at 4°C. The sinking rate of eggs and embryos was also measured at various pressure. The data suggest that pressure does not significantly influence the sinking rate. There appears to be a wide variation of sinking rates of eggs within the same brood. based on a simulated model of sinking rate, egg development was studied at increasing pressure. Pressure of 5–20 atm accelerates the rate of cleavage and therefore the 32-celled stage is attained within 5–8 h, while at 1 atm it took 13 h to reach the same stage. Pressure thus seems to have some influence on the duration of the development of different developmental stages of krill embryos.     

Anatomy and muscle activity of the dorsal fins in bamboo sharks and spiny dogfish during turning maneuvers

Stability and procured instability characterize two opposing types of swimming, steady and maneuvering, respectively. Fins can be used to manipulate flow to adjust stability during swimming maneuvers either actively using muscle control or passively by structural control. The function of the dorsal fins during turning maneuvering in two shark species with different swimming modes is investigated here using musculoskeletal anatomy and muscle function. White‐spotted bamboo sharks are a benthic species that inhabits complex reef habitats and thus have high requirements for maneuverability. Spiny dogfish occupy a variety of coastal and continental shelf habitats and spend relatively more time cruising in open water. These species differ in dorsal fin morphology and fin position along the body. Bamboo sharks have a larger second dorsal fin area and proportionally more muscle insertion into both dorsal fins. The basal and radial pterygiophores are plate‐like structures in spiny dogfish and are nearly indistinguishable from one another. In contrast, bamboo sharks lack basal pterygiophores, while the radial pterygiophores form two rows of elongated rectangular elements that articulate with one another. The dorsal fin muscles are composed of a large muscle mass that extends over the ceratotrichia overlying the radials in spiny dogfish. However, in bamboo sharks, the muscle mass is divided into multiple distinct muscles that insert onto the ceratotrichia. During turning maneuvers, the dorsal fin muscles are active in both species with no differences in onset between fin sides. Spiny dogfish have longer burst durations on the outer fin side, which is consistent with opposing resistance to the medium. In bamboo sharks, bilateral activation of the dorsal in muscles could also be stiffening the fin throughout the turn. Thus, dogfish sharks passively stiffen the dorsal fin structurally and functionally, while bamboo sharks have more flexible dorsal fins, which result from a steady swimming trade off. J. Morphol. 274:1288–1298, 2013. © 2013 Wiley Periodicals, Inc.     

A new species, Gazza squamiventralis, from the East Coast of Africa (Perciformes: Leiognathidae)

Gazza squamiventralis sp. nov. is described as the fifth species of the genus, based on the holotype and eight paratypes, 42–96 mm in standard length, collected along the east coast of Africa, from Kenya to Mozambique. The species is similar to other congeners in general appearance, differing clearly from them in having the ventrolateral surface of the body scaled anterior to a line from the pectoral fin base to the pelvic fin origin (vs naked) and a smooth supraorbital ridge (vs finely serrated). Additionally, the species differs from G. dentex, G. rhombea, and G. achlamys in having the dorsolateral surface of the body scaled anterior to a vertical through the tip of the posterior branch of the supratemporal canal (vs corresponding region naked), and from G. minuta in having the first dorsal fin pterygiophore narrowly expanded anteriorly, with a concave margin (vs broadly expanded, with a convex or linear margin), and a short antrorse extension of the first anal fin pterygiophore (vs long). A key to the five species of the genus Gazza is provided. Received: May 30, 2000 / Revised: September 16, 2000 / Accepted: January 16, 2001     

A new species,gerres infasciatus, from the gulf of thailand (perciformes: Gerreidae)

Gerres infasciatus sp. nov. is described from the holotype and two paratypes, 125–140 mm in standard length (SL), collected off Samut Prakan, northern Gulf of Thailand. The species is similar toG. filamentosus Cuvier andG. macracanthus Bleeker in general appearance, having an elongated second dorsal fin spine, but differs from them in having 39 or 40 pored lateral line scales, the first and second soft dorsal fin ray tips yellow in fresh specimens, a narrow, faint dusky-yellowish margin on the upper membrane of the spinous dorsal fin (between 4th–9th spines), the distal part of the pelvic fin (between 1st–5th soft rays) white for 1/3–1/2 of each ray length (lost after preservation), bands absent on the body in both fresh and preserved specimens, a smaller orbit diameter (11.4–12.4% of SL), a longer second dorsal fin spine (48.0–68.9% of SL), and shorter second and third anal fin spines (10.7–11.2% and 10.4–11.3% of SL), respectively.     

A new loach, Cobitis shikokuensis (Teleostei: Cobitidae), from Shikoku Island, Japan

A new species of spinous loach, Cobitis shikokuensis, is described based on 297 specimens from Shikoku Island, Japan. The new species was formerly known as the Shikoku group of Cobitis takatsuensis. It can be distinguished from other species of Cobitis and closely related genera by a combination of the following characters: dorsal fin with 6 branched soft rays; anal fin with 5 branched soft rays; one brownish streak across eye from the tip of nose, no streak on cheek; a black spot smaller than eye diameter near the dorsal corner of the caudal fin base; 3–5 small brownish speckles on ventral side of caudal peduncle; high caudal peduncle with well-developed fleshy keels on dorsal and ventral side; a lamina circularis at base of dorsal part of pectoral fin absent; first branched soft ray of pectoral fin broad in males; pectoral soft rays widely branched from the approximate midpoint; last anal fin ray with 2 elements; interorbital width 11.2–17.1% of head length.     

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.     

A new species of amblycipitid catfish, <Emphasis Type="Italic">Xiurenbagrus gigas</Emphasis> (Teleostei: Siluriformes), from Guangxi,China

A new species of amblycipitid catfish is described based on five specimens (88.0–164.5mm in standard length: SL) collected from the vicinity of Duan, Guangxi Zhuangzu Autonomous Region, southern China. The new species, Xiurenbagrus gigas, is different from all other known amblycipitid catfish, but similar to X. xiurenensis by having two patches of vomerine teeth. The new species can be distinguished from X. xiurenensis by having a larger head (head length: 27.9–34.9% vs. 21.8–26.4% SL; head depth: 14.4–17.9% vs. 12.4–14.1% SL; head width: 22.4–29.4% vs. 18.1–20.3% SL), lower adipose fin (4.6–6.0% vs. 6.5–8.3% SL), shorter distance from dorsal origin to adipose origin (25.7–32.0% vs. 32.9–38.9% SL), longer dorsal fin (21.2–24.9% vs. 16.2–19.1% SL), longer pectoral fin (18.4–20.7% vs. 13.5–16.8% SL), longer pelvic fin (13.1–14.3% vs. 8.8–11.8% SL), and more gill rakers (7–9 vs. 5). Xiurenbagrus gigas, the largest known species in the family Amblycipitidae, is distributed in the Xijiang River, the longest tributary of the Zhujiang (Pearl) River basin.     

Three‐dimensional reconstruction of the musculature of various life cycle stages of the cycliophoran Symbion americanus

Cycliophora is a very recently described phylum of acoelomate metazoans with a complex life cycle and a phylogenetic position that has been under debate ever since its discovery in 1995. Symbion americanus, which lives attached to the mouthparts of the American lobster, Homarus americanus, represents the second species described for the phylum. Aiming to increase the morphological knowledge about this cryptic clade, the present study describes the muscle arrangement of the feeding stage, the attached Prometheus larva with the dwarf male inside, the free living male, the Pandora larva, and the chordoid larva of S. americanus using actin staining and confocal laser scanning microscopy. 3D reconstructions of the muscular systems are presented. In the feeding stage, circular muscles compose the buccal funnel aperture. In addition, a pair of muscles runs longitudinally in the buccal funnel. A complex sphincter was found just proximally to the anus, and six longitudinal muscles run from the trunk constriction (“neck”) in basal direction. The musculature of the larval stages and the dwarf male is very complex and includes longitudinal muscles that run dorsally and ventrally. In addition, we found dorso‐ventral muscles. The male has a complex posterior muscle apparatus in the vicinity of the penis. In this stage, X‐ and V‐shaped structures were identified on the dorsal and the ventral side, respectively. Pandora and chordoid larvae possess additional circular muscles. We discuss our findings with respect to muscle elements of other metazoan groups and the chordoid larva of Symbion pandora. J. Morphol., 2009. © 2008 Wiley‐Liss, Inc.     

The <Emphasis Type="Italic">Leiognathus aureus</Emphasis> complex (Perciformes: Leiognathidae) with the description of a new species

Taxonomic analysis of a group of morphologically similar ponyfishes (Perciformes: Leiognathidae) establishes a complex comprising three valid species: Leiognathus aureus Abe and Haneda, 1972, widely distributed in the western Pacific Ocean (Taiwan, Philippines, Thailand, Singapore, Indonesia, and northern Australia); L. hataii Abe and Haneda, 1972, currently known only from Ambon, Indonesia; and L. panayensis sp. nov. Kimura and Dunlap, currently known only from Panay Island, the Philippines. The L. aureus complex can be defined by the following combination of characters: mouth protruding forward, not downward; small but sharp conical teeth uniserially on jaws; a black line between lower margin of eye and lower jaw articulation; and lateral line incomplete, ending below posterior part of dorsal fin base or on anterior caudal peduncle. Leiognathus hataii differs from both L. aureus and L. panayensis in having a large dark blotch below the spinous dorsal fin base and fewer counts of scales (lateral line scales 50–58 vs. 64–85 in the latter two species; scales above lateral line 7–10 vs. 12–18; scales below lateral line 22–26 vs. 30–41). Leiognathus panayensis is distinguished from L. aureus in having a deeper body (41–51% SL vs. 35–45% SL in the latter), long posterior limb of maxilla (21–25% HL vs. 15–23% HL), wholly scaled belly (vs. naked along preanal median keel), and a dark blotch on nape (vs. absent).     

A new species,Gazza rhombea, from the Indo-West Pacific, with a redescription ofG. achlamys Jordan & Starks, 1917 (Perciformes: Leiognathidae)

Gazza rhombea sp.nov. is described from 61 type and 81 non-type specimens, 19–176 mm in standard length, collected from the Indo-West Pacific. The species is similar to other congeners in general body appearance, differing from them in having the dorsolateral surface of the body scaled anterior to the dorsal fin origin, but not reaching to a vertical through the tip of the posterior branch of the supratemporal canal (vs. dorsolateral surface of body naked anterior to base of sixth or seventh dorsal fin spine base inG. achlamys; dorsolateral surface of body with scales extending anteriorly beyond tip of posterior branch of supratemporal canal inG. minuta), and having a long narrow anterodorsal extension from the subocular silvery region, in contact with the orbit only proximally (vs. broad anterodorsal extension, with proximal and distal contact with orbit inG. dentex).Gazza rhombea is also distinguishable fromG. achlamys andG. minuta by the morphology of the first dorsal fin pterygiophore, and the neural and hemal spines of the fifth preural centrum. The new species has usually been misidentified asG. achlamys, which is redescribed here, owing to its similarly deep-bodied appearance.     

<Emphasis Type="Italic">Trichiurus nickolensis</Emphasis>, a new hairtail from Australia belonging to the <Emphasis Type="Italic">Trichiurus russelli</Emphasis> complex (Perciformes: Trichiuridae)

A new hairtail, Trichiurus nickolensis, is described on the basis of ten specimens collected off northwestern Australia, off the Northern Territory, and in the Gulf of Carpentaria, Queensland. The new species strongly resembles T. brevis Wang and You in Wang et al., 1992, off Hainan Island, South China Sea, and T. russelli Dutt and Thankam, 1966, off the Waltair Coast, Andhra Pradesh, India, in having the highest point of the supraoccipital crest situated directly above the posterior margin of the eye and a relatively short caudal peduncle. Trichiurus nickolensis differs from those two species in being strongly pigmented on the anterior section of the dorsal fin membrane (vs. slightly pigmented), and having a dorsal head margin that appears concave in lateral view, rises gently from snout tip to above middle of orbit, and then extends more steeply to dorsal fin origin (vs. rising gently from tip of snout to dorsal fin origin). The new species also has a greater number of dorsal fin rays (III, 138–143 vs. III, 127–132 and III, 127–131 in T. brevis and T. russelli, respectively) and total vertebrae (160–166 vs. 147–155 and 149–153), and shorter preanal length (mean 30% TL vs. 33% TL and 35% TL), head length (11% TL vs. 12% TL and 13% TL) and upper jaw length (4% TL vs. 5% TL and 5% TL).     

宽鳃鮟鱇属一新种

20世纪70年代以前,全世界已知宽鳃鮟鱇属Sladenia Regan(1908)鱼类仅有3种。1980～1982年期间,东海水产研究所"东方"号和南海水产研究所"南锋"号调查船分别在东海和南海的大陆架渔场调查时,共采集到4尾珍稀的深海鮟鱇鱼类。经研究,认为这4尾标本是1新种,定名为朱氏宽鳃鮟鱇Sladenia zhui sp.nov.。     

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.     

A pelagic larva of <Emphasis Type="Italic">Plagiopsetta glossa</Emphasis> (Pleuronectiformes,Samaridae), characterized by a trailing gut and S-shaped pelvic bone: description and phylogenetic considerations

 The pelagic larval stage of a pleuronectiform samarid, Plagiopsetta glossa, is described and illustrated, for the first time, from a 8.4-mm BL postflexion specimen collected off Tosa Bay, southern Japan. The larva is distinctive in having broad, semitransparent pterygiophore zones on the dorsal and anal fins, a trailing gut, flexible S-shaped pelvic bone, and a skin fold under the throat. These characteristics are shared with poecilopsettid larvae, suggesting a close relationship between the two families.     

Redescription of a rare deep-sea batfish, <Emphasis Type="Italic">Halieutopsis bathyoreos</Emphasis> (Lophiiformes: Ogcocephalidae)

Halieutopsis bathyoreos Bradbury, 1988 (Lophiiformes: Ogcocephalidae), previously described only on the basis of the holotype (62.6mm in standard length) from the central North Pacific, is redescribed on the basis of the holotype and six additional specimens (41.2–68.7mm in standard length) collected from the western South Pacific, off Papua New Guinea, and the western North Pacific, including the Japanese Archipelago. Halieutopsis bathyoreos is distinguished from its congeners by having a shelflike rostrum extending anteriorly well beyond the mouth, a dorsal escal lobe slightly bisected ventrally, an illicial cavity square in outline and completely visible in ventral view, and lacking tubercles on the ventral surface of the disk. The following characters are newly added to the diagnoses of this species: rostrum width 21–29% of head length, tubercles on the dorsal surface of the disk about half the diameter of those on the lateral margin, and 13–15 large lateral-line scales on the tail.