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The size and shape of red blood cells (RBCs) provide key information on life-history strategies in vertebrates. However, little is known about how RBC shape evolved in response to environmental factors, body size and the role of evolutionary rate. Here, we analysed RBC morphometrics in a set of Teleostei (bony fishes) and Elasmobranchii (sharks and rays) species testing the hypothesis that phylogenetic relationship explains species occupation of morphospace. We collected data on cell and nucleus area and volume, nucleus:cytoplasm ratio and shape factor for 65 species belonging to 28 orders. Then, we built phylomorphospaces separately for bony fish and sharks and rays. To test whether phylogenetic relationships predicted phenotypic similarity, we calculated multivariate phylogenetic signal. We also estimated the evolutionary rate of RBC shape for each node and tip using ridge regression. Finally, we tested whether habitat and body size influenced RBC shape using a PGLS. We found a significant phylogenetic signal in RBC shape for bony fish, but not sharks and rays. Saltwater teleost species were more clustered than freshwater ones in the phylomorphospace, suggesting clade disparity. Accordingly, the rate of evolution was highly heterogeneous, with significant decrease in Acanthopterygii. Neither habitat nor body size influenced RBC shape. In conclusion, RBC shape seems to have evolved in fishes in response to multiple selective pressures independent of life-history characters.

Vertebrates have four visual cone opsin classes that, together with a light-sensitive chromophore, provide sensitivity from the ultraviolet to the red wavelengths of light. The rhodopsin-like 2 (RH2) opsin is sensitive to the centre blue-green part of the spectrum, which is the most prevalent light underwater. While various vertebrate groups such as mammals and sharks have lost theRH2gene, in teleost fishes this opsin has continued to proliferate. By investigating the genomes of 115 teleost species, we find thatRH2shows an extremely dynamic evolutionary history with repeated gene duplications, gene losses and gene conversion affecting entire orders, families and species. At least four ancestral duplications provided the substrate for today’sRH2diversity with duplications occurring in the common ancestors of Clupeocephala, Neoteleostei, and Acanthopterygii. Following these events,RH2has continued to duplicate both in tandem and during lineage specific genome duplications. However, it has also been lost many times over so that in the genomes of extant teleosts, we find between zero to eightRH2copies. Using retinal transcriptomes in a phylogenetic representative dataset of 30 species, we show thatRH2is expressed as the dominant green-sensitive opsin in almost all fish lineages. The exceptions are the Osteoglossomorpha (bony tongues and mooneyes) and several characin species that have lostRH2, and tarpons, other characins and gobies which do not or only lowly express the gene. These fishes instead express a green-shifted long-wavelength-sensitiveLWSopsin. Our study highlights the strength of using modern genomic tools within a comparative framework to elucidate the detailed evolutionary history of gene families.

To investigate chromosome evolution in fish species, we newly mapped 181 markers that allowed us to construct a yellowtail (Seriola quinqueradiata) radiation hybrid (RH) physical map with 1,713 DNA markers, which was far denser than a previous map, and we anchored the de novo assembled sequences onto the RH physical map. Finally, we mapped a total of 13,977 expressed sequence tags (ESTs) on a genome sequence assembly aligned with the physical map. Using the high-density physical map and anchored genome sequences, we accurately compared the yellowtail genome structure with the genome structures of five model fishes to identify characteristics of the yellowtail genome. Between yellowtail and Japanese medaka (Oryzias latipes), almost all regions of the chromosomes were conserved and some blocks comprising several markers were translocated. Using the genome information of the spotted gar (Lepisosteus oculatus) as a reference, we further documented syntenic relationships and chromosomal rearrangements that occurred during evolution in four other acanthopterygian species (Japanese medaka, zebrafish, spotted green pufferfish and three-spined stickleback). The evolutionary chromosome translocation frequency was 1.5-2-times higher in yellowtail than in medaka, pufferfish, and stickleback.

A new tilefish, Branchiostegus biendong, is described on the basis of three specimens (181–209 mm in standard length [SL]) collected from a local fish market of Quy Nhon on the South China Sea coast of central Vietnam. It can be distinguished from 17 congeners in having the following combination of characters: six diagonal scale rows exposed on cheek; cheek scales moderately large (diameter 2.2–2.5% SL); predorsal ridge black; cheek almost silver with an oval-shaped, yellow blotch along ventral margin of eye; dorsal fin translucent yellowish with narrow black margin overlapping stronger yellowish coloration dorsally; upper lobe of caudal fin with 5–6 yellow stripes and tip with black blotch; and lower lobe of caudal fin navy blue. A key to five species of Branchiostegus from Vietnamese waters is provided.

The presence of Aluterus monoceros (Linnaeus, 1758) in Mar del Plata, Argentina (38° S) was registered over 40 years ago. This new report extends its southernmost distribution limit to 39° S (Necochea: ~ 120 km). The presence of the species could be associated to the warm subtropical water derived from the Brazilian continental shelf. The hypothesis was tested with satellite images of the sea surface temperature recorded during the cruise the specimen was caught.

A total of 1,471 specimens of 16 species of flatfishes (Pleuronectiformes) were caught during 48 sampling campaigns between July 2005 and June 2007 at ten stations in Guanabara Bay, Rio de Janeiro, Brazil. Paralichthyidae was the dominant family, with Etropus crossotus as the dominant species. The outer stations, especially those on the western side of the lower estuary, were distinguished as a result of their higher abundance of flatfishes and number of species. The spatial distribution of E. crossotus and its population structure indicate that this species is an estuarine resident despite the apparent reduction in its area of occupation within the estuarine complex. Among the other species, nine were classified as marine stragglers (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus and Trinectes paulistanus) and three as estuarine opportunists (Bothus robinsi, Citharichthys macrops and Syacium papillosum); another three could not be classified due to the small number of captures or lack of previous data (S. tessellatus, A. lineatus and C. spilopterus). Resumo: Um total de 1.471 espécimes de 16 espécies de linguados (Pleuronectiformes) foram capturados durante 48 campanhas de amostragem entre julho de 2005 e junho de 2007 em dez estações na Baía de Guanabara, Rio de Janeiro, Brasil. Paralichthyidae foi a família dominante, com Etropus crossotus como a espécie dominante. As estações externas, especialmente aquelas no lado ocidental do baixo estuário, foram distinguidas como resultado de sua maior abundância de linguados e número de espécies. A distribuição espacial de E. crossotus e sua estrutura populacional indicam que esta espécie é uma residente estuarina, apesar da aparente redução em sua área de ocupação dentro do complexo estuarino. Dentre as outras espécies, nove foram classificadas como migrantes marinhos (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus e Trinectes paulistanus) e três como oportunistas estuarinos (Bothus robinsi, Citharichthys macrops e Syacium papillosum); outras três não puderam ser classificados devido ao pequeno número de capturas ou falta de dados prévios (S. tessellatus, A. lineatus e C. spilopterus).

While much of the functional work on suction feeding has involved members of Acanthopterygii, an earlier cypriniform radiation led to over 3200 species filling nearly every freshwater trophic niche. Within the great majority of acanthomorph clades that have been investigated suction feeding and the underlying morphology responsible for the generation of rapid suction have been largely conserved. This conserved feeding-apparatus is often associated with increasing the force experienced by the prey item, thus making a strike on elusive prey more effective. Cypriniforms' trophic anatomy is comprised of a number of novelties used for benthic feeding, which characterized early members of this clade. The modified cypriniform structure of the oral jaws represents a situation in which a particular type of suction feeding allowed for probing the benthos with a more functionally maneuverable anatomy. Requisite evolutionary modifications included origin and elongation of a median kinethmoid, duplications of certain divisions of the muscles of the adductor mandibulae, and origin of a dorsal, intra-buccal muscular palatal organ used in winnowing detritus. The elongated kinethmoid (coupled with modified adductor muscles) allowed for a type of premaxillary protrusion that decoupled the upper and lower jaws, enabled premaxillary protrusions with a closed mouth, and facilitated benthic feeding by increasing functional flexibility. The resultant flow of fluid generated by cypriniforms is also quite flexible, with multiple instances of peak flow in a single feeding event. This greatly modified morphology allowed for a degree of kinematic maneuverability not seen within most acanthomorphs. Later cypriniform radiations into piscivorous, insectivorous, or planktivorous feeding guilds were associated with shortening of the kinethmoid and with simplified morphology of the adductor, likely involving an emphasis on ram feeding. Although this suite of morphological novelties seemingly originated within the context of benthic feeding, with minimal modifications these anatomical features were later coopted during radiations into different functional niches.

A redescription and diagnosis of Trimma tevegae , based on 50 additional specimens from the type locality at Rabaul, New Britain is provided, and contrasted with the redescription and diagnosis of T. caudomaculatum , based on the type material and an additional 22 specimens from various western Pacific localities. Trimma tevegae may most easily be recognized by the lack of a blue stripe (dark in preservative) in the dorsal midline of the snout, and a short second spine in the first dorsal fin, reaching posteriorly to the origin or first few ray bases of the second dorsal fin. Trimma caudomaculatum can be identified by the blue stripe from the snout along the dorsal midline, the blue spots and stripes in front of the eye, on the opercle and beneath the eye (dark in preserved material), and the very elongate second dorsal spine, usually extending to beyond the end of the second dorsal fin. Three similar-looking new species are described. Trimma burridgeae and T. hollemani are morphologically very close to each other, differing mainly in the length of the second dorsal spine (to the posterior base of the second dorsal fin or beyond in T. burridgeae ; to the anterior base of that fin in T. hollemani ). These two species differ by over 9% of the bases of the COI gene. Trimma corerefum is the most distinctive of the species, differing in lacking a blue stripe on the dorsal surface of the snout, in the pigment pattern around the eye, in having fewer cephalic sensory papillae (free neuromasts) in rows d ʹ, ea , ep , f, r and ot , and in a shorter fifth pelvic fin ray (34–45% length of fourth pelvic ray). The morphological differences between the species are reinforced by the results of a barcode analysis of the COI gene, based on 105 specimens.

The gilthead seabream and the soles, Senegalese sole and common sole, are important species in Mediterranean aquaculture. In this chapter, a review of the current genomic resources available for these species is carried out. First, transcriptome information, their main characteristics, and the high-throughput gene expression tools developed in these three species are described. Second, the current genetic maps and their applications for the identification of QTLs for traits of interest in aquaculture are also reported. Moreover, the main features of Senegalese sole genome draft are analyzed and its structure is compared with other Acanthopterygii confirming a high degree of synteny that allows for comparative genomic studies. To show the relevance of these genomic resources to enhance the aquaculture procedures, the SoleaDB database that hosts the genomic information for soles is described. Moreover, main results obtained using transcriptomic tools to decipher the regulatory pathways that control larval development, nutrition and metabolism, as well as the health and welfare status are reviewed. Future directions of genomic research and the impact of novel species-specific applications and resources are highlighted.

Basic and neutral neurohypophyseal (NH) nonapeptides have evolved from vasotocin (VT) by a gene duplication at the base of the gnathostome lineage. In teleosts, VT and IT are the basic and neutral peptides, respectively. In the present study, VT and IT precursor genes of Heteropneustes fossilis and Clarias batrachus (Siluriformes, Ostariophysi) were cloned and sequenced. The channel catfish Icatalurus punctatus NH precursor sequences were obtained from EST database. The catfish NH sequences were used along with the available Acanthopterygii and other vertebrate NH precursor sequences to draw phylogenetic inference on the evolutionary history of the teleost NH peptides. Synteny analysis of the NH gene loci in various teleost species was done to complement the phylogenetic analysis. In H. fossilis, the NH transcripts were also sequenced from the ovary. The cloned genes and the deduced precursor proteins showed conserved characteristics of the NH nonapeptide precursors. The genes are expressed in brain and ovary (follicular envelope) of H. fossilis with higher transcript abundance in the brain. The addition of the catfish sequences in the phylogenetic analysis revealed that the VT and IT precursors of the species-rich superorders of teleosts have a distinct phylogenetic history with the Acanthopterygii VT and IT precursors sharing a less evolutionary distance and the Ostariophysi VT and IT having a greater evolutionary distance. The genomic location of VT and IT precursors, and synteny analysis of the NH loci lend support to the phylogenetic inference and suggest a footprint of fish- specific whole genome duplication (3R) and subsequent diploidization in the NH loci. The VT and IT precursor genes are most likely lineage-specific paralogs resulting from differential losses of the 3R NH paralogs in the two superorders. The independent yet consistent retention of VT and IT in the two superorders might be directed by a stringent ligand-receptor selectivity.

The taxon Beloniformes represents a heterogeneous group of teleost fishes that show an extraordinary diversity of jaw morphology. I present new anatomical descriptions of the jaw musculature in six selected beloniforms and four closely related species. A reduction of the external jaw adductor (A1) and a changed morphology of the intramandibular musculature were found in many Beloniformes. This might be correlated with the progressively reduced mobility of the upper and lower jaw bones. The needlefishes and sauries, which are characterised by extremely elongated and stiffened jaws, show several derived characters, which in combination enable the capture of fish at high velocity. The ricefishes are characterised by several derived and many plesiomorphic characters that make broad scale comparisons difficult. Soft tissue characters are highly diverse among hemiramphids and flying fishes reflecting the uncertainty about their phylogenetic position and interrelationship. The morphological findings presented herein may help to interpret future phylogenetic analyses using cranial musculature in Beloniformes.