Characiform Fish Research Articles

First report of four characiform fishes (Ostariophysi: Characiformes) for Uruguay

In this article the authors present the first report of four characiform fish species for Uruguay, extending their current distribution to the middle and lower Uruguay River basin: Astyanax saguazu Casciotta, Almirón and Azpelicueta, 2003; Hypobrycon poi Almirón, Casciotta, Azpelicueta and Cione, 2001; Leporinus amae Gody, 1980; Cyphocharax saladensis (Meinken, 1933). These species were previously recorded from either the upper Uruguay River, Patos-Merín lagoon system or Paraná River. Color pattern in life for A. saguazu and H. poi are described for the first time.

Are characiform fishes Gondwanan in origin? Insights from a time-scaled molecular phylogeny of the Citharinoidei (Ostariophysi: Characiformes).

Fishes of the order Characiformes are a diverse and economically important teleost clade whose extant members are found exclusively in African and Neotropical freshwaters. Although their transatlantic distribution has been primarily attributed to the Early Cretaceous fragmentation of western Gondwana, vicariance has not been tested with temporal information beyond that contained in their fragmentary fossil record and a recent time-scaled phylogeny focused on the African family Alestidae. Because members of the suborder Citharinoidei constitute the sister lineage to the entire remaining Afro-Neotropical characiform radiation, we inferred a time-calibrated molecular phylogeny of citharinoids using a popular Bayesian approach to molecular dating in order to assess the adequacy of current vicariance hypotheses and shed light on the early biogeographic history of characiform fishes. Given that the only comprehensive phylogenetic treatment of the Citharinoidei has been a morphology-based analysis published over three decades ago, the present study also provided an opportunity to further investigate citharinoid relationships and update the evolutionary framework that has laid the foundations for the current classification of the group. The inferred chronogram is robust to changes in calibration priors and suggests that the origins of citharinoids date back to the Turonian (ca 90 Ma) of the Late Cretaceous. Most modern citharinoid genera, however, appear to have originated and diversified much more recently, mainly during the Miocene. By reconciling molecular-clock- with fossil-based estimates for the origins of the Characiformes, our results provide further support for the hypothesis that attributes the disjunct distribution of the order to the opening of the South Atlantic Ocean. The striking overlap in tempo of diversification and biogeographic patterns between citharinoids and the African-endemic family Alestidae suggests that their evolutionary histories could have been strongly and similarly influenced by Miocene geotectonic events that modified the landscape and produced the drainage pattern of Central Africa seen today.

Profiles of sex steroids, fecundity and spawning of a migratory characiform fish from the Paraguay–Paraná basin: a comparative study in a three-river system

This study investigated for the first time the reproductive biology of Prochilodus lineatus in a system of rivers in southeastern Brasil, relating it to the role of tributary rivers in the reproductive success of this important commercial fish in the Upper Paraná River basin, where a cascade of hydroelectric dams were deployed. Specimens were caught bimonthly in three river sites: (S1) Grande River, downstream from the Porto Colômbia dam; (S2) Pardo River; and (S3) Mogi Guaçu River. Sex steroid plasma levels, fecundity, follicular atresia, oocyte diameter and gonadosomatic index (GSI) were compared among sites. In S1, fish exhibited changes in the reproductive parameters: lower GSI, oocyte diameter and fecundity and higher follicular atresia index, when compared to S2 and S3. Frequency of maturing fish was higher in S3 and spawning was only registered in S3. In sites S2 and S3, plasma concentrations of testosterone and 17β-estradiol in females and testosterone in males showed wide variations following gonadal maturation. Fish from S1 showed few significant variations in sex steroid concentrations throughout the gonadal cycle. These results indicate that P. lineatus does not reproduce in Grande River (S1), but probably uses the Pardo River (S2) as a migratory route towards the Mogi Guaçu River (S3) where they complete gonadal maturation and spawning. Our findings contribute for understanding the reproductive biology of P. lineatus and to highlight the importance of tributaries in impounded rivers as a favourable environment for migration and spawning of fish.

Role of HSP70 in the regulation of the testicular apoptosis in a seasonal breeding teleost Prochilodus argenteus from the São Francisco river, Brazil

This study investigated the relationship among heat shock protein 70 (HSP70), proliferating cell nuclear antigen (PCNA), and testicular apoptosis during a breeding cycle of Prochilodus argenteus, a neotropical migratory characiform fish of importance in commercial fishery from the São Francisco River basin. A total of 48 (12 fish/sampling) adult males were caught using casting and drifting nets in four samplings from June 2008 to March 2009. Immunohistochemistry, Western blotting, terminal transferase-mediated dUTP nick-end labeling (TUNEL), enzyme-linked immunosorbent assay (ELISA), and caspase-3 colorimetric assay were assessed in different phases of spermatogenesis. Labeling for HSP70 occurred in spermatogonia (SPG(A) 18.0±1.5 and SPGB 27.9±1.0 in 100 mm(2), respectively) and Sertoli cells in all sampling periods, with higher values in June (resting period) while spermatocytes were labeled in September (maturation period) and December (ripe period). For PCNA, immunoreaction was predominant in spermatogonia in June and September, while primary spermatocytes were labeled mainly in December (18.7±2.0). TUNEL-positive reaction occurred throughout the sampling periods, and labeling was detected in the nucleus of germ cells in all developmental phases, except spermatozoa. By ELISA, total HSP70 in testis increased significantly from June to December, and decreased in March (regression period), P<0.05. Caspase-3 activity decreased from June to December and increased in March. Taken together, our results suggest that HSP70 may protect the germ cells from caspase-3-dependent apoptosis during testicular activity and, reduction of HSP70 and increase of apoptosis contribute for testicular remodeling after the breeding season in wild populations of P. argenteus in the São Francisco River.

Oocyte adhesiveness and embryonic development ofAstyanax bimaculatus(Linnaeus, 1758) (Pisces: Characidae)

This study shows for the first time the presence of a jelly coat on oocytes of neotropical Characiformes fish. This structure could be responsible for the adhesiveness of Astyanax bimaculatus oocytes, a species widely distributed in South America including in the São Francisco River basin in Brazil. Adult specimens of A. bimaculatus were submitted to artificial reproduction in order to analyse the egg morphology and embryonic development. The eggs were fertilised and kept in incubators with a water temperature of 24°C so that embryogenesis could be monitored. Ovulated and unfertilised oocytes were also collected and submitted to routine histological techniques. Astyanax bimaculatus oocytes were found to be spherical, yellowish, and covered by a thin jelly coat with a slightly adhesive surface. The mean oocyte diameter was 1.03 ± 0.03 mm, the perivitelline space was 0.21 ± 0.02 mm and the jelly coat's thickness was 0.04 ± 0.01 mm. Positive periodic acid-Schiff (PAS) stain and Alcian blue stain pH 2.5 indicated the presence of neutral glycoproteins, and carboxylated acid glycoconjugates on the jelly coat that formed mucosubstances that may be associated with egg adhesiveness. At a water temperature of 24°C, blastopore closure and hatching occurred at 5 h and 17 h after fertilisation, respectively. The results of this study provide essential information for phylogenetic studies and for a better understanding of the reproductive strategy of A. bimaculatus, currently included in the incertae sedis group of the Characidae family due to the lack of monophyly among the families of the group.

Phylogenetic relationships of Paleotetra, a new characiform fish (Ostariophysi) with two new species from the Eocene-Oligocene of south-eastern Brazil

Paleotetra, a new characiform genus with two new species (P. entrecorregos and P. aiuruoca) from Palaeogene deposits of south-eastern Brazil is described. The fossil material is made up of two articulated specimens preserved as impressions in lateral view and including some bones and teeth. The new genus is hypothesized to be deeply inserted within the Characidae based on the apomorphic lack of a supraorbital bone, the low number of vertebrae (35), and the presence of four teeth in the inner series of the premaxilla; however, the new species cannot be assigned to any modern genus. Relationships of the two new species are further tested in a phylogenetic analysis along with 160 other characiform species using 360 morphological characters (150 coded for Paleotetra entrecorregos and 123 for P. aiuruoca), further supporting their recognition as characid characiforms. These results document the evolution of these characid lineages as early as the Eocene-Oligocene.

Early ontogeny of aquarium-raised Moenkhausia sanctaefilomenae (Characiformes: Characidae)

The ontogeny of the characiform fish Moenkhausia sanctaefilomenae, from early embryogenesis through the early larval period, is presented. Fertilized eggs were slightly elliptical, measured 0.6 mm in diameter, and were surrounded by a fertilization envelope 0.8 mm in diameter. Much of the early embryogenesis is complete after 12 h, with cleavages complete after 2.5 h and gastrulation complete after 3 additional hours. The initial formation of organs needed for predatory behaviors occurs within 72 h. Growth of the cranial elements is quite dramatic and allows for the capture of relatively large prey at the onset of exogenous feeding. Elaboration of these elements continues into the early larval period.

Nuclear-follower foraging associations among Characiformes fishes and Potamotrygonidae rays in clean waters environments of Teles Pires and Xingu rivers basins, Midwest Brazil

During under and overwater observations were recorded nuclear-follower foraging associations among three species of characiform fishes - Chalceus epakros, Hemiodus semitaeniatus and Hemiodus unimaculatus - and a freshwater stingray species - Potamotrygon orbignyi - in the Teles Pires and Xingu rivers basins, Midwest Brazil. The teleost fishes were observed closely following the stingrays during the behavior of stirring the substrate to uncover invertebrates, which cause discrete sediment clouds. Apparently this sediment perturbation attracts the fishes that approached the foraging stingrays to feed on small preys and other food types exposed this way. This is a typical example of a commensal relationship in which one participant is benefited while the other is unaffected, and represents the second published record of nuclear-follower feeding association between potamotrygonid rays and teleost fishes, demonstrating the potential of naturalistic studies in discovering new interactions involving species of freshwater fish.

Isolation and characterization of eight polymorphic microsatellite markers for the migratory characiform fish, Salminus brasiliensis

Eight polymorphic microsatellite loci were isolated and characterized for the migratory freshwater fish Salminus brasiliensis (Characiformes) and tested on 67 individuals from nine geographically distant locations along the Paraná Basin. The number of alleles per locus ranged from four to 14, with observed heterozygosity estimates ranging from 0·15 to 0·79.

Morphological plasticity associated with environmental hypoxia in characiform fishes from neotropical floodplain lakes

The ability to develop reversible dermal extensions on the lower jaw in some South American characiform fishes has been proposed as a way to optimize the performance of aquatic surface respiration (ASR) during hypoxic conditions. These structures are formed by edema of the hypodermal tissues and can develop in a large proportion of individuals inhabiting a lake within a few hours following daily changes in dissolved oxygen. Our study report the development of dermal lip protuberances in elevenspeciesof characiform fishes associated with periods of strong environmental hypoxia in floodplain lakes of Salado River, Argentina. Protuberances occurred in different basic forms in fishes with divergent head morphology (genera Astyanax, Ctenobrycon, Aphyocharax, Brycon, Mylossoma, Tri- portheus, Oligosarcus and Acestrorhynchus). The dis- covery of dermal projections on the anterior border of maxillary bone extends the known range of structures affected by lip protuberances. Dermal structures began to develop simultaneously in both jaws below dissolved oxygen (DO) concentrations of 1.20-1.75 mgl �1 and rose in a steep manner as oxygen level decreased. The degree of morphological plasticity differed among traits and species. The shape of response of morphology to DO was similar to that previously reported on ASR, providing additional evidence about the functional link between these traits. Our results suggests that dermal lip protuberances are widely spread among characiform fishes, affecting several mouth structures. The different types of protuberances would make up for the limi- tations imposed by body size and mouth shape and position on the performance of ASR in fishes with divergent morphology.

The South American freshwater fish Prochilodus lineatus (Actinopterygii: Characiformes: Prochilodontidae): new species in Vietnamese aquaculture

The freshwater characiform fish Prochilodus lineatus is a detritivorous species that has its native distribution area in South America but has been imported to China for aquaculture purposes. This is the first time that it is being reported in Vietnam, both from aquaculture and captured from a river channel. According to local authorities, the species is becoming increasingly important in local aquaculture and its spread can be expected. Keeping in mind the high biomass production in the rivers of its native distribution area, a successful establishment of P. lineatus into Vietnamese fresh waters may exert serious impacts on the local ecosystems.

Redescripción de Parodon caliensis y Saccodon dariensis (Characiformes: Parodontidae)

Redescription of Parodon caliensis and Saccodon dariensis (Characiformes: Parodontidae). Parodontidae family is a group of Characiformes fishes distributed throughout South America and parts of Panama, except in the basins of the southern Bahia state in Brasil on the Atlantic coast, Patagonia and the Amazon river channel. The family includes three genera: Apareiodon Eigenmann 1916, Parodon Valenciennes 1849 y Saccodon Kner 1863, 28 recognized species and two valid genera: Parodon and Saccodon. Redescription of Parodon caliensis and Saccodon dariensis is carried out based on type, and topotypic material from Colombia. Significant differences were found in morphometric, meristic, osteologic and color characters. S. dariensis is widely distributed but P. caliensis is restricted to the upper Cauca River drainage. Three species are considered herein as synonyms of S. dariensis: Apareiodon dariensis, A. compressus and S. caucae. Sexual dimorphism is described for both species.

Life-history of the South American darter, Characidium pterostictum (Crenuchidae): evidence for small scale spatial variation in a piedmont stream

The present study compares the reproduction, condition and size of the small characiform fish, Characidium pterostictum, sampled at close sites differing in severity of flash flood effects. Data were obtained from seasonal samples in two sites situated 8 km apart in the same stream. In the upstream site, habitat is more severely affected by flash floods than in the downstream site, and this difference was hypothesized to produce differences in life history and individual reproduction trade-off patterns, as predicted by life-history theory. The results provided evidence for small-scale spatial variation in life-history and trade-off patterns within the studied population. At the most severely disturbed site, C. pterostictum displayed a trade-off pattern that favored reproductive life-span (e.g., larger size, higher and seasonally stable condition, larger mean size of mature females) over instantaneous reproductive output (lower gonadosomatic index), while the opposite pattern was observed in the less disturbed site. Because of the differences in disturbance effects between each sampling site, these results suggest that within-stream variability in the severity of hydrological disturbance can influence life-history patterns at small spatial scales. An implication of the results is that fish occupying areas that are hydrologically more variable within a stream are not necessarily at an energetic or reproductive disadvantage, but may be simply under environmental conditions that favor distinct patterns of energy allocation (or trade-offs) and population persistence, as predicted by life-history theory. Therefore, plasticity in life-history is expected to be common in stream fish populations that are widespread in a stream system with spatially variable or patchy habitat characteristics.

Cretaceous characiform fishes (Teleostei: Ostariophysi) from Northern Tethys: description of new material from the Maastrichtian of Provence (Southern France) and palaeobiogeographical implications

Abstract The order Characiformes (Teleostei: Otophysi) is one of the most diverse freshwater fish groups. It contains around 1400 living species in South and Central America and Africa. Their fossil record starts in the Cretaceous on both continents and also in Europe. Here, we describe and discuss the occurrences of new characiform fish teeth from Provence (Maastrichtian, S. France). Five morphological types are recognized. They belong to possibly three different taxa, and they are regarded as Characiformes indet. However, two of them have resemblances to alestin fishes and could be related to the African family Alestidae. The characiform fishes from Provence are among the oldest known in Europe, together with a freshwater characiform fish occurring in Romania, and the recently described marine fish Sorbinicharax from Italy. The biogeographical history of characiform fishes has been intensively discussed during the last three decades. The group is generally accepted to be Gondwanan and its diversification linked with the break-up of this continent, with two main scenarios depending on whether the group is archaeo- or telolimnic. Some authors also propose a Pangaean origin. The recent discoveries of Sorbinicharax and of the fossils from Provence change our view on the Cretaceous characiform diversity and their early ecology, and they also enable us to re-evaluate the proposed biogeographical scenarios, reinforcing the hypothesis of the telolimny of the group.

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RT-PCR was used for amplifying Piaractus mesopotamicus growth hormone (GH) cDNA obtained from mRNA extracted from pituitary cells. The amplified fragment was cloned and the complete cDNA sequence was determined. The cloned cDNA encompassed a sequence of 543 nucleotides that encoded a polypeptide of 178 amino acids corresponding to mature P. mesopotamicus GH. Comparison with other GH sequences showed a gap of 10 amino acids localized in the N terminus of the putative polypeptide of P. mesopotamicus. This same gap was also observed in other members of the family. Neighbor-joining tree analysis with GH sequences from fishes belonging to different taxonomic groups placed the P. mesopotamicus GH within the Otophysi group. To our knowledge, this is the first GH sequence of a Neotropical characiform fish deposited in GenBank.

Colonization, population expansion, and lineage turnover: phylogeography of Mesoamerican characiform fish

We present a phylogeographical analysis of four genera of Mesoamerican primary freshwater fish ( Brycon , Bryconamericus , Eretmobrycon , and Cyphocharax ). Three hundred and thirty-nine individuals were genotyped into one of 31 operational taxonomic units (OTUs) based on the nucleotide sequence of their mitochondrial ATPase 6 & 8 genes (842‐839 bp). Contrary to inference based on the species-level taxonomy of these genera, molecular data identified only a single case of sympatry between closely related OTUs, despite extensive parapatry. Polytomies dominate the mtDNA-based phylogenies and demonstrate multiple, noncontemporaneous waves of rapid expansion across Mesoamerica from South American sources. Analyses based on genetic distances observed among congeneric species of Mesoamerican primary freshwater fishes in comparison to divergence between transisthmian marine fishes permit the strong inference that the Pliocene rise of the Panama land bridge provided the first opportunity for the colonization of Mesoamerica by Characiform fishes. We develop a priority-effect model, based on the assumption that genetically closely related OTUs share similar ecological niches, to reconcile the general lack of contemporary sympatry between closely related OTUs with the substantial historical connectivity among Mesoamerican drainages demonstrated by the rapid expansion of Brycon , Bryconamericus , and Cyphocharax . Finally, in most cases, we infer that the westerly limits of freshwater fish distributions in Mesoamerica are more consistent with being defined by ecological factors rather than by dispersal limitation. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 235‐255.

Redescrição e osteologia de Bryconamericus exodon Eigenmann, 1907 (Ostariophysi, Characiformes, Characidae)

Apresenta-se a redescrição de Bryconamericus exodon Eigenmann (1907), espécie-tipo do gênero, uma descrição osteológica da espécie, uma comparação com outras espécies de Characiformes e comentários sobre seu relacionamento com outros caracídeos. Bryconamericus exodon é facilmente distinta de todas as demais espécies do gênero por possuir os lobos superior e inferior da nadadeira caudal castanho-escuros; aproxima-se das espécies de Bryconamericus com corpo alongado e baixo, menos de 30% do comprimento padrão, boca terminal e dentes da série externa do pré-maxilar desalinhados. Compartilha com outros Characidae um palatino fenestrado, perfurado ou adelgaçado, em sua porção médio-anterior, e um pós-cleitro 3 alongado e com aproximadamente a mesma largura em toda sua extensão, sinapomorfias adicionais para os Characidae com ii, 8 raios na nadadeira dorsal e quatro dentes na série interna do pré-maxilar.

Relationships among characiform fishes inferred from analysis of nuclear and mitochondrial gene sequences

Suprafamilial relationships among characiform fishes and implications for the taxonomy and biogeographic history of the Characiformes were investigated by parsimony analysis of four nuclear and two mitochondrial genes across 124 ingroup and 11 outgroup taxa. Simultaneous analysis of 3660 aligned base pairs from the mitochondrial 16S and cytochrome b genes and the nuclear recombination activating gene (RAG2), seven in absentia (sia), forkhead (fkh), and α-tropomyosin (trop) gene loci confirmed the non-monophyly of the African and Neotropical assemblages and corroborated many suprafamilial groups proposed previously on the basis of morphological features. The African distichodontids plus citharinids were strongly supported as a monophyletic Citharinoidei that is the sistergroup to all other characiforms, which form a monophyletic Characoidei composed of two large clades. The first represents an assemblage of both African and Neotropical taxa, wherein a monophyletic African Alestidae is sister to a smaller clade comprised of the Neotropical families Ctenolucidae, Lebiasinidae, and the African Hepsetidae, with that assemblage sister to a strictly Neotropical clade comprised of the Crenuchidae and Erythrinidae. The second clade within the Characoidei is strictly Neotropical and includes all other Characiformes grouped into two well supported major clades. The first, corresponding to a traditional definition of the Characidae, is congruent with some groupings previously supported by morphological evidence. The second clade comprises a monophyletic Anostomoidea that is sister to a clade formed by the families Hemiodontidae, Parodontidae, and Serrasalmidae, with that assemblage, in turn, the sistergroup of the Cynodontidae. Serrasalmidae, traditionally regarded as a subfamily of Characidae, was recovered as the sistergroup of (Anostomoidea (Parodontidae + Hemiodontidae)) and the family Cynodontidae was recovered with strong support as the sistergroup to this assemblage. Our results reveal three instances of trans-continental sistergroup relationships and, in light of the fossil evidence, suggest that marine dispersal cannot be ruled out a priori and that a simple model of vicariance does not readily explain the biogeographic history of the characiform fishes.

Osteology and morphology of the characiform fish Alestes stuhlmanniiPfeffer, 1896(Alestidae) from the Rufiji River basin, East Africa

The osteology of a population of the characiform fish Alestes stuhlmannii, from the Rufiji River basin of Tanzania, is described, and meristic and morphometric data from over 100 specimens, ranging from 15·5 to 218 mm standard length are given. Two allometric changes occur during growth of this fish: both the number of gill rakers and the interorbital width relative to the head length increase with size. There are also changes in tooth form associated with growth in A. stuhlmannii, with the unicuspid teeth of juveniles becoming almost molariform in adults. This change in dentition with age, and therefore size, may have implications for recognizing taxa, some of which (the fossil genera Sindacharax and Bunocharax, and the living dwarf petersiines) have been distinguished by jaw or dental characters.

Short-term cold storage of sperm from six neotropical characiformes fishes

Sperm of the following Neotropical Characiformes fish species were tested for cold storage: Brycon lundii, Piaractus mesopotamicus, Leporinus elongatus, Leporinus friderici, Prochilodus lineatus and Prochilodus marggravii. Each sperm sample was split into two aliquots. The first was placed into a plastic bag with air or oxygen and the second, in a plastic tube with air. The samples were maintained at temperatures between 1.7-4.9 ºC. The rate of sperm motility was estimated using a 50 mM NaCl solution as the activating solution. The shortest sperm storage duration (7 h) was recorded for L. friderici, when the sperm motility rate reached ~ 30%, whereas the longest duration (20 h) was obtained with the sperm of P. lineatus. A fertilisation test using Prochilodus marggravii sperm refrigerated for 8 h yielded 88-90% of viable embryos. The refrigerated storage method could be of practical applications, especially in fish reproductive management at hatchery stations.