Hypural Plate Research Articles

Culture protocols of the Metallic Shiner for ornamental aquaculture

AbstractObjectiveWhile North American fishes are often overlooked by the ornamental fish industry, there is growing interest in fishes native to the southeastern USA, a hot spot for fish diversity. The Metallic Shiner Pteronotropis metallicus, a small‐bodied leuciscid native to Florida and Georgia, is sometimes available in the ornamental fish trade through wild collection and limited captive production. This species exhibits a distinctive color pattern straddling the lateral line: a dorsal pink to red line, fading to a black to blue stripe. This group of minnows is largely unknown to ornamental aquaculture and lacks defined culture protocols. Our objective was to develop culture protocols for the Metallic Shiner.MethodsFollowing collection of wild broodstock, we used routine culture methods to experimentally determine substrate preference, egg incubation, egg disinfection, larval feeding, and larval development.ResultMetallic Shiner spawning was more successful on yarn mops compared with other media, with average output of >50 embryos per tank per day. Hatching success was similar for static incubators (24%) and upwelling incubators (20%) and was also similar among egg disinfection treatments (iodine, hydrogen peroxide, and formalin). Larval feeding regimes altered survival, with Otohime A1 exhibiting higher survival (44%) over 14 days posthatch (dph) and better growth than other feeding regimes. During the developmental trial with water temperature at a relatively constant 25°C, length increased from 5 mm notochord length (4 dph) to 8.7 mm standard length (45 dph), with significant milestones occurring at 4 dph (swim bladder inflation), 16 dph (flexion), and 23 dph (hypural plate formation).ConclusionThese data provide basic culture information for the Metallic Shiner while also providing a place of reference to begin investigating culture protocols for related species, including species of conservation concern.

An enigmatic interstitial trichomycterine catfish from south-eastern Brazil found at about 1000 km away from its sister group (Siluriformes: Trichomycteridae)

During recent field studies in the upper Rio Paraná basin, south-eastern Brazil, a small undescribed trichomycterine catfish with interstitial habits was found. The combination of morphological character states exhibited by this species did not allow placement to any genus from eastern South America. A multigene phylogeny here performed strongly supported the new taxon as sister to Scleronema. Due to the confusing generic classification of the Trichomycterinae, the new taxon is formally placed in a new subgenus of Scleronema (Plesioscleronema subgen. nov.), instead of in a new monotypic genus. The inclusion of the new taxon in Scleronema implicated in a review of generic diagnostic morphological characters. Two apomorphic character states were found to be useful to diagnose Scleronema in this broader sense: presence of a skin flap on the posterior margin of the opercle and a unique frontal bone morphology. Scleronema auromaculatum spec. nov. differs from other trichomycterines by a unique morphology of the area involving the postero-dorsal portion of the quadrate and the adjacent region of the hyomandibula, the uroneural separated by the dorsal hypural plate by an interspace, and a widened hemal spine of the preural centre 2. The about 1000 km gap between the area where the new species was collected and the nearest collecting site of its sister group is probably a consequence of both anthropic environmental degradation and the specialised interstitial habits in this fish group, making it difficult to be found in ichthyological inventories.

A comparative study on the caudal skeleton of goatfishes (Teleostei: Perciformes: Mullidae) from the Western Indo-Pacific region: An additional taxonomic tool

The present study was conducted to provide a comparative description of the caudal skeleton of the mullid fishes (family Mullidae) from the western Indo-Pacific region. Nine species belonging to three genera were studied, i.e., Mulloidichthys vanicolensis, Parupeneus heptacanthus, P. macronemus, P. margaritatus, P. rubescens, Upeneus doriae, U. sundaicus, U. tragula, and U. vittatus. Based on X-ray imaging, the configuration of the caudal skeleton and the caudal-fin formula are reported for all species. The new data reveal that the shape, size and degree of fusion of individual bones of the caudal skeleton and the caudal fin-ray formula can be different among genera, and also between congeneric species. The neural spine of PU2 is short in all species, except in P. macronemus. The hypural plates 1 and 2 are usually separated, but fused in M. vanicolensis and U. doriae. The hypural plates 3 and 4 are fused in all species except in P. rubescens. The parhypural is long and broad in all examined species, the highest relative length of the parhypural is present in P. macronemus. The uroneural 2 is absent in M. vanicolensis, U. doriae, U. tragula, and U. vittatus, but present in the remaining species. These differences indicate that the structures of the caudal skeleton are additional useful tools in the taxonomic study of mullid species.

Habitat influences skeletal morphology and density in the snailfishes (family Liparidae)

We tested the hypothesis that deep-sea fishes have poorly mineralized bone relative to shallower-dwelling species using data from a single family that spans a large depth range. The family Liparidae (snailfishes, Cottiformes) has representatives across the entire habitable depth range for bony fishes (0 m–> 8000 m), making them an ideal model for studying depth-related trends in a confined phylogeny. We used micro-computed tomography (micro-CT) scanning to test three aspects of skeletal reduction in snailfishes (50 species) across a full range of habitat depths: 1) reduction of structural dimensions, 2) loss of skeletal elements, and 3) reduction in bone density. Using depth data from the literature, we found that with increasing depth, the length of the dentary, neurocranium, and suborbital bones decreases. The ventral suction disk decreases width with increasing maximum habitat depth and is lost entirely in some deeper-living taxa, though not all. Although visual declines in bone density in deeper-living taxa were evident across full skeletons, individual densities of the lower jaw, vertebra, suction disk, hypural plate, and otoliths did not significantly decline with any depth metric. However, pelagic and polar taxa tended to show lower density bones compared to other species in the family. We propose that skeletal reductions allow snailfishes to maintain neutral buoyancy at great depths in the water column, while supporting efficient feeding and locomotion strategies. These findings suggest that changes in skeletal structure are non-linear and are driven not only by hydrostatic pressure, but by other environmental factors and by evolutionary ancestry, calling the existing paradigm into question.

The fast and the tendinous? Locomotor modifications of the caudal peduncle in Gila spp. from the American Southwest

In the American Southwest, the fishes within the genus Gila evolved in an environment with seasonal rainstorms that caused stochastic flooding. Some species within this genus, such as bonytail (Gila elegans), possess locomotor morphologies that are similar to those seen in high-performance swimmers such as tuna and lamnid sharks. These shared features include a shallow caudal peduncle, lunate tail, and mechanisms to transmit force from the anterior musculature to the tail fin. We compared the skeletal anatomy of the caudal region of bonytail to roundtail chub (Gila robusta) and humpback chub (Gila cypha) to determine which vertebral elements have been modified to create a shallow peduncle. We also tested the tensile strength of the red (slow oxidative) axial muscle by performing a standard stress test. If the muscle can withstand a large load, this suggests it may play a tendon-like role in transmitting force from the anterior muscle to the hypural plate of the tail. Lastly, we measured the collagen content of the red axial muscle (visualized using serial sections and Masson’s trichrome stain) to determine if increased tensile strength is associated with increased collagen content. We found bonytail caudal peduncles are characterized by acute vertebral spines and have red axial muscle that can resist tearing under tension. Roundtail chub peduncles are characterized by relatively more obtuse angles and the red muscle tears easily under tension. Humpback chub possess an intermediate morphology, with relatively obtuse vertebral spine angles and the red muscle can resist tearing under tension. Bonytail have increased collagen content in posterior red axial muscle compared to the anterior musculature also suggesting a tendon-like role of the posterior red muscle. In combination with previous studies of swimming performance, our findings suggest that the axial musculature of bonytail may play a role in transmitting force directly to the shallow peduncle in a manner similar to that of the great lateral tendon of scombrids.

Axial skeleton morphology of the Western Palearctic aphaniid fishes (Teleostei: Cyprinodontiformes; Family: Aphaniidae)

AbstractThe axial skeleton morphology of eighteen aphaniid species was examined for the first time by X‐ray radiography, a non‐lethal method. The number of total vertebrae in the genus Aphanius is ranged from 26 to 29, in Aphaniops, it is ranged from 24 to 28, and in Paraphanius mento, it is ranged from 26 to 27. The vertebral column in Aphanius was often slightly curved, and it is varied from almost straight (most common) to slightly or strongly curved and straight in two others. The caudal skeleton of the family Aphaniidae is characterized by a single and completely fused hypural plate, and a total number of 9–12 branched segmented soft rays, a single and elongate epural bone. All examined species of the genus Aphanius and Paraphanius mento displayed a straight epural bone in their caudal skeleton, while it was often sinuous‐like and thick in all species of the genus Aphaniops. This study supports the assumption that a sinuous epural is likely the first detected morphological synapomorphy for the “inner” clade of Aphaniops. The family Aphaniidae is closer to Cyprinodontidae, Valenciidae and Fundulidae than other cyprinodontiforms in the caudal skeleton, which is in agreement with the multigene phylogeny of cyprinodontiforms.

Integrative taxonomy reveals a new species of pacu (Characiformes: Serrasalmidae: Myloplus) from the Brazilian Amazon

ABSTRACT Pacus of the genus Myloplus represent a formidable taxonomic challenge, and particularly so for the case of M. asterias and M. rubripinnis, two widespread and common species that harbor considerable morphological diversity. Here we apply DNA barcoding and multiple species discovery methods to find candidate species in this complex group. We report on one well-supported lineage that is also morphologically and ecologically distinct. This lineage represents a new species that can be distinguished from congeners by the presence of dark chromatophores on lateral-line scales, which gives the appearance of a black lateral line. It can be further diagnosed by having 25-29 branched dorsal-fin rays (vs. 18-24), 89-114 perforated scales from the supracleithrum to the end of hypural plate (vs. 56-89), and 98-120 total lateral line scales (vs. 59-97). The new species is widely distributed in the Amazon basin, but seems to have a preference for black- and clearwater habitats. This ecological preference and black lateral line color pattern bears a striking similarity to the recently described silver dollar Metynnis melanogrammus.

Evidence for the existence and diversification of a new group of cichlids in the Miocene lakes of the Tugen Hills, Kenya

Evidence for the existence and diversification of a new group of cichlids in the Miocene lakes of the Tugen Hills, Kenya

Recently diverged killifishes: Morphometry and caudal skeleton osteology of two members of the Aphanius dispar species group (Aphaniidae, Teleostei)

Recently diverged killifishes: Morphometry and caudal skeleton osteology of two members of the Aphanius dispar species group (Aphaniidae, Teleostei)

Histomicroscopy and normal anatomy of the adult killifish Aphanius hormuzensis (Teleostei; Aphaniidae) from the Persian Gulf coastal environment.

The histomicroscopy and normal anatomy of the major body organ systems were investigated in the adult killifish, Aphanius hormuzensis using histological examination, X-ray imaging, double staining, light microscopy and scanning electron microscopy (SEM). Based on the histomicroscopic observations, the kidney, liver and swim bladder in the studied species were comparable to other fish models. The anterior portion of the kidney is bulbous, while the posterior portion is narrow and elongated; the liver has a single lobe and the swim bladder is a single-chambered organ with no connection to the digestive tract (physoclistous). X-ray imaging and double staining examination showed 12 abdominal and 15 caudal vertebrae and a single hypural plate in the caudal skeleton. According to light microscopy, the scales were rounded to pentagonal in shape with three types of radii (primary, secondary and tertiary), and the urohyal bone was elongated. SEM microscopy showed a single row of tricuspid teeth on the upper and lower jaw, respectively, each tooth has two lateral cusps that are shorter than the middle one. The number of teeth was 17-18 in the upper jaw and 19-20 in the lower jaw. The saccular otoliths were rounded-trapezoid in shape with a moderately incised and V-shaped excisura. The members of killifishes are an important group for biologists because of their evolutionary properties, regeneration capacity and usefulness as biological control and also for the ecotoxicological assessment of environmental pollution. The outcomes of this study may provide a useful basis for future research on the genus Aphanius.

An evaluation of a double-tailed deformity in a coral-reef surgeonfish Acanthurus nigrofuscus (Acanthuridae) using micro-computed tomography.

X-ray micro-computed tomography scans were used to examine the caudal-fin structure of an unusual double-tailed deformity in an adult brown surgeonfish Acanthurus nigrofuscus from the Great Barrier Reef. In both this case and in a similar double-tailed deformity in a juvenile Tomini surgeonfish Ctenochaetus tominiensis from the Philippines, the caudal fin was duplicated along the dorsoventral axis. Detailed examination of the A. nigrofuscus specimen revealed that the deformity was associated with duplication and reflection of the hypural plates and the posterior vertebrae, yet the fish survived to adulthood, indicating that the effects of duplication on survival may be limited.

The caudal skeleton of Arambourgthurus scombrurus (Arambourg, 1967), a Paleogene oceanic surgeonfish

Abstract A detailed description of the caudal skeleton of the Paleogene nasine surgeonfish Arambourgthurus scombrurus is provided herein. The compound (urostylar) centrum is fused with a large, nearly triangular, thick hypural plate, formed by consolidated hypurals 1–4. The compound centrum supports a large autogenous parhypural bearing a thick and blunt hypurapophysis. Hypural 5 is a small triangular bone. There is a single elongate autogenous uroneural and three epurals, the first of which is remarkably stout and elongate, with its proximal end embraced by the open neural arch of the second preural vertebra. The haemal spines of the second and third preural vertebrae are fused to their respective centra. The phylogenetic relationships of Arambourgthurus are discussed. Arambourgthurus shares some features with the Eocene Sorbinithurus and the Miocene Marosichthys, and together they constitute a monophyletic group that represents the sister group of the pair formed by the extant genus Naso and the fossil ...

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COVER PHOTOGRAPH: Stage 41. Early pre‐hatching. The tip of the tail extends over the head to the posterior of the eye. The iridocytes start to turn a brown‐orange color. A few small round teeth are visible on the jaws. There are 30‐32 cartilaginous vertebrae with neural and hemal arches forming. Ossification of the vertebrae and arches is underway. In the tail, the hypural plate cartilages are forming. From: Embryonic development of the annual killifish Austrofundulus limnaeus: An emerging model for ecological and evolutionary developmental biology research and instruction; Jason E. Podrabsky, Claire L. Riggs, Amie L. Romney, S. Cody Woll, Josiah T. Wagner, Kristin M. Culpepper and Timothy G. Cleaver; Developmental Dynamics 246:779–801.

Spawning, Embryology, and Larval Development of the Milletseed Butterflyfish Chaetodon miliaris in the Laboratory

AbstractAs part of the Rising Tide Conservation effort to advance marine ornamental aquaculture the Milletseed Butterflyfish Chaetodon miliaris (also known as Millet Butterflyfish) was chosen as a candidate species for developing butterflyfish aquaculture methodologies. Thirty‐five mature Milletseed Butterflyfish were imported to University of Florida's Tropical Aquaculture Laboratory in Ruskin, Florida, from The Rainbow Reef exhibit at Aulani, a Disney Resort and Spa in Ko Olina, Hawaii, for evaluation. Spawning behavior was documented through personal and video observation five times. Eggs were collected immediately after spawning and checked for fertilization, and a sample of 100 ± 10 eggs were photographed every hour until hatching to document embryological development. Larval development was monitored through multiple rearing trials. Larvae were stocked into 128‐L, cylindrical, rearing tanks at 15–20 larvae/L and fed nauplii of the copepod, Parvocalanus crassirostris, and the microalgae, Tisochrysis lutea, was added to green the water. Samples of larvae were measured using notochord length from the tip of the snout to the edge of the notochord prior to flexion, SL from the tip of the snout to the edge of the hypural plate, and TL. Spawning occurred in broodstock tanks between one dominant male and a single female with a large, swollen abdomen. Eggs of the Milletseed Butterflyfish were small, spherical, pelagic, and transparent and hatched after a 28‐h period at 25.5°C. Newly hatched larvae had unpigmented eyes and a closed digestive tract and measured 1.20–1.24 mm in notochord length. Larvae were capable of feeding at 4 d posthatch (dph), fully absorbed the yolk sac by 7 dph, and began forming the tholichthys plates at 24 dph. Larvae survived to 44 dph in preliminary culture trials and measured 6.49–6.56 mm TL. Further investigation into the culture requirements of Milletseed Butterflyfish will supply a crucial base for developing aquaculture protocols for other marine ornamental species.

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from the upper río Magdalena basin, Colombia

Trichomycterus tetuanensis, new species, is described from the río Tetuan, upper río Magdalena basin in Colombia. The new species is distinguished by its margin of caudal fin conspicuously emarginate, in combination with a high number of opercular odontodes (21-39), reflected externally in the large size of the opercular patch of odontodes, 3 irregular rows of conic teeth in the upper jaw, 42-52 interopercular odontodes, 8 branchiostegal rays, 37 post Weberian vertebrae, 7 branched pectoral-fin rays, hypural 3 separated from hypural plate 4+5, and background coloration light brown with darker dots uniformly sparse on dorsum and sides of trunk. Some apomorphic characters informative for the phylogenetic affinities of the new species within Trichomycterus are discussed.

Aphanius marassantensis, a new toothcarp from the Kızılırmak drainage in northern Anatolia (Cyprinodontiformes: Cyprinodontidae)

Aphanius marassantensis, new species, is described from the Kızılırmak River drainage in northern Anatolia based on colouration, meristic and morphometric characters, and the mtDNA COI barcode region. It is distinguished from other Anatolian Aphanius by one or several of the following characters: a stout body shape (BD/SL 28.2-39.6%), complete scale cover, and 25-28 scales along the lateral line. Males have 8-13 dark-brown lateral bars, of which the antepenultimate bar anterior to the caudal-fin base is 0.9-1.8 times wider than the anterior white interspace, 2-3 vertical rows of spots on the caudal fin, a black dorsal fin, sometimes with a narrow whitish-grey base, a white anal fin with 1-3 rows of black spots, in some individuals with a black margin, and hyaline pelvic fins. Females do not have vertical rows of dark-brown spots on caudal or anal fins, but numerous dark-brown spots on the flanks, arranged in 1-3 lateral rows behind a vertical from the dorsal-fin base. Their dorsal fin is hyaline with tiny dark-brown spots on rays and membranes; pectoral fins, caudal and anal fins are hyaline, and one prominent large dark-brown blotch is situated in mid-lateral position on the hypural plate. The new species is also distinguished by 11 fixed, diagnostic nucleotide substitutions in the mtDNA COI barcode region. The description of this new species, which brings the number of Anatolian Aphanius species to 12, underlines the character of Anatolia as a region of extraordinarily high biodiversity.

A New Species ofLeporinus(Characiformes: Anostomidae), from the Orinoco Basin, Venezuela

A new species of Leporinus in the L. cylindriformis group is described from the Río Orinoco basin, Venezuela. This new species can be separated from congeners by the combination of an extremely dorsoventrally slender body, the presence of a prominent midlateral spot positioned ventral to the dorsal fin, and the absence of any other intense dark pigmentation. The new species is most similar to L. aripuanaensis from the Rio Aripuanã, Brazil, but can be most easily differentiated from that species by the absence (79% of specimens) or faint presence (21% of specimens) of a circular dark spot over the hypural plate in the new species, versus the presence of an intensely pigmented dark spot in that position, respectively. It can be further distinguished from L. aripuanaensis by the modal number of predorsal scales (12 versus 11). Small juveniles of the two species do not differ morphometrically, but their allometric growth trajectories differ. Above 70 mm SL, the new species differs from L. aripuanaensis in interorbital width (34–44% HL versus 30–34%) and eye diameter (29–34% HL versus 26–30% HL). This new species represents the most recent of a long series of newly discovered taxa within Leporinus and reinforces the Orinoco Basin as a region of high endemism.

The Untold Story of the Caudal Skeleton in the Electric Eel (Ostariophysi: Gymnotiformes: Electrophorus)

Alternative hypotheses had been advanced as to the components forming the elongate fin coursing along the ventral margin of much of the body and tail from behind the abdominal region to the posterior margin of the tail in the Electric Eel, Electrophorus electricus. Although the original species description indicated that this fin was a composite of the caudal fin plus the elongate anal fin characteristic of other genera of the Gymnotiformes, subsequent researchers proposed that the posterior region of the fin was formed by the extension of the anal fin posteriorly to the tip of the tail, thereby forming a “false caudal fin.” Examination of ontogenetic series of the genus reveal that Electrophorus possesses a true caudal fin formed of a terminal centrum, hypural plate and a low number of caudal-fin rays. The confluence of the two fins is proposed as an additional autapomorphy for the genus. Under all alternative proposed hypotheses of relationships within the order Gymnotiformes, the presence of a caudal fin in Electrophorus optimized as being independent of the occurence of the morphologically equivalent structure in the Apteronotidae. Possible functional advantages to the presence of a caudal fin in the genus are discussed.

The caudal skeleton of extant and fossil cyprinodontiform fishes (Teleostei: Atherinomorpha): comparative morphology and delimitation of phylogenetic characters

The caudal skeleton of teleost fishes of the order Cyprinodontiformes is described and compared on the basis of 394 extant and eight fossil species, supporting delimitation of 21 phylogenetic characters, of which 13 are firstly reported. The Cyprinodontiformes are unambiguously diagnosed by the presence of a single, blade-like epural, and by principal caudal-fin rays continuous on upper and lower hypural plates. Monophyly of the suborder Cyprinodontoidei is supported by the widened neural and hemal spines of the preural centrum 3 and presence of a spine-like process on the stegural, and monophyly of the Aplocheiloidei by the absence of radial caudal cartilages. A keel-shaped lateral process on the compound centrum supports monophyly of the Nothobranchiidae. Some characters of the caudal skeleton in combination to other osteological features indicate the cyprinodontiform fossil genus †Prolebias to be a paraphyletic assemblage; †P. aymardi, †P. delphinensis and †P. stenoura, the type species of the genus, all from the Lower Oligocene of Europe, possibly are closely related to recent valenciids; †“P.” meridionalis from the Upper Oligocene of France is an incertae sedis cyprinodontid; and, †“P”. cephalotes, †“P”. egeranus and †“P”. malzi from the Upper Oligocene-Lower Miocene of Europe are closely related to poeciliids, probably closely related to the recent African genus Pantanodon due to they sharing unique derived features of pelvic fin, branchial arches and jaws.

Glyptothorax jayarami, a new species of catfish (Teleostei: Sisoridae) from Mizoram, northeastern India

A new sisorid catfish, Glyptothorax jayarami, is described from the Kaladan basin of Mizoram, India. It is characteristicin having densely tuberculate skin; an elongate, ovoid thoracic adhesive apparatus with an oval central depression fromwhich the ridges on the apparatus diverge; two blackish-brown blotches at caudal-fin base behind the hypural plate; welldeveloped plicae on the ventral surfaces of simple and adjacent branched rays of pectoral and pelvic fins; a narrow caudal peduncle (5.5–7.9 % SL) and long 2 + 6–7 gill rakers on the first branchial arch.