Characidae Research Articles

Karyotypic characterization of two species of the genusSerrapinnus(Characiformes, Characidae), with the description of a structural polymorphism inS. heterodon

The family Characidae, one of the largest and more diversified fish families in the Neotropical region, is certainly not a monophyletic group, which is supported by the cytogenetic data showing its extensive chromosome variability. In this work, two species of the genus Serrapinnus, S. heterodon and S. piaba, from the Sao Francisco river basin were analyzed. Both species presented the same diploid number, 2n=52 chromosomes, and the same karyotypic formula, 16m+20sm+14st+2a. The heterochromatin distribution, evidenced by C-banding, was also similar between both species. On the other hand, two NORs were evidenced in S. heterodon, while a multiple NOR system was characterized in S. piaba, both confirmed by silver nitrate staining as well as by fluorescent in situ hybridization with 18S rDNA probe. Furthermore, two additional karyotypes (cytotypes) were observed in S. het- erodon, with 15m+20sm+14st+3a and 17m+20sm+14st+1a chromosomes, respectively, characterizing a structural chromosome polymorphism in the population. The differences between the three S. heterodon karyotypic forms are probably due to pericentric inversions related to the 8 th and 26 th chromosome pairs.

Karyotype characterization and gene mapping of 5S and 18S rDNA in three species of Oligosarcus (Teleostei: Characidae)

AbstractOligosarcus is a monophyletic Characidae genus with 15 species described, distributed through the freshwater bodies of South and Southeastern parts of South America. Recently, a new classification of this genus has been proposed based on morphological characters and mtDNA sequence, but still now there are many uncertainties in relation to the taxonomic classification of this group. In this study, three Oligosarcus species were chromosomically analyzed using conventional and molecular techniques in order to characterize their karyotipic constitution. All the three species presented 2n = 50 chromosomes, distributed as follows: O. jenynsii—2M/24SM/10ST/14A, O. pintoi—2M/20SM/12ST/16A, and O. hepsetus—2M/16SM/16ST/16A. A metacentric chromosome, larger than any other chromosome in the complement, was identified in all cases and probably corresponds to the marker chromosome of the Characidae family. The first submetacentric chromosome may also represent a marker chromosome, but at genus or subfamily lev...

Intromittent Organ in the Genus Monotocheirodon (Characiformes: Characidae)

We herein document intromittent organs in four Peruvian populations of inseminating fishes of the family Characidae, genus Monotocheirodon, which may comprise new species. All females histologically analyzed from these populations, as well as a female of Monotocheirodon pearsoni, had spermatozoa within the ovary, confirming insemination. Male M. pearsoni produced aquasperm with spherical nuclei (diameter 1.6 μm), with no intromittent organ. On the other hand, males from the Peruvian populations of Monotocheirodon produced spermatozoa with slightly ovoid to elongate nuclei (lengths 1.8–4.1 μm) and possessed distinct intromittent organs. Some populations with more elongate sperm nuclei had longer intromittent organs. Each intromittent organ consisted of an elongate extension of the body wall encompassing an extension of the common sperm duct and urinary duct, which joined with one another near the base of the organ and opened to the outside at the pointed tip of the organ. Skeletal muscle cells are present throughout the organ. At the base, the skeletal muscle is oriented around the organ (circular) possibly forming a sphincter. The skeletal muscle along the organ is mainly oriented longitudinally, although some circular bundles are present. These males are apparently able to manipulate the organs by means of this muscle. The wall of the sperm duct within the organ is folded and lined with a low cuboidal epithelium. The posterior portions of the testes of males with the longest intromittent organs lack spermatogenic tissue and serve as open storage regions for mature spermatozoa.

Biologia reprodutiva e reprodução induzida de duas espécies de Characidae (Osteichthyes, Characiformes) da bacia do São Francisco, Minas Gerais, Brasil

Astyanax bimaculatus (Linnaeus, 1758) e Tetragonopterus chalceus Spix & Agassiz, 1829 são duas importantes espécies de peixes forrageiros da bacia do São Francisco. Espécimes destas duas espécies foram submetidos à indução da desova através de hipofisação, para observação de aspectos reprodutivos e obtenção de subsídios para definição de protocolo de reprodução artificial. Machos e fêmeas receberam dose única de extrato bruto de hipófise de carpa comum (6 mg/kg de peixe). A extrusão de ovócitos foi realizada cerca de 12,8 e 11 h após a aplicação da injeção de hipófise, respectivamente para A. bimaculatus e T. chalceus, com a temperatura da água a 26ºC. Mais de 70% das fêmeas das duas espécies responderam positivamente ao tratamento e as taxas médias de fertilização dos ovos foram acima de 70%. Os ovócitos de A. bimaculatus e T. chalceus são esféricos, opacos, demersais, levemente adesivos, de coloração amarela ou parda, e contendo em média respectivamente 4774 e 2563 ovos por grama de ova. O desenvolvimento embrionário nas duas espécies foi rápido, com duração de menos de um dia, estando a temperatura da água entre 24 e 25ºC.

Chromosomal analysis of Astyanax fasciatus (PISCES, CHARACIDAE) from the Araguari river, Uberlândia, MG, Brazil

The genus Astyanax is one of the most numerous of the family Characidae, comprising a large number of similar-shaped species, but displaying innumerable karyotypic variations in its chromosome number and/or structure. The literature describes A. fasciatus populations with diploid chromosome numbers varying from 2n = 45 to 2n = 48. In this study, A. fasciatus specimens captured in the Araguari River (Alto Paraná basin) were cytogenetically characterized, revealing a diploid chromosome number of 2n = 46. The nucleolar organizing regions (NORs), detected with silver nitrate staining, showed a multiple system with two pairs of marked chromosomes. These findings are congruent with those of other studies involving populations of the same species.

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A new inseminating fish species of the family Characidae, Bryconadenos tanaothoros, from tributaries of the upper rio Xingu and upper rio Tapajós basins, Mato Grosso, Brazil is described as the type species of a new genus. This new species and the genus are characterized by a glandular organ on the anterior region of the anal fin of sexually mature males, curved lower jaw teeth, and an inseminating reproductive mode. This new genus is hypothesized as most closely related to Attonitus, a genus with three inseminating species from Peru. Bryconadenos and Attonitus are suggested as related to certain inseminating, but undescribed characid species of uncertain relationships that are similar in certain respects to species of the glandulocaudine Planaltina and to the inseminating species of Knodus. These and a few other inseminating characids are included in a previous tentative characid subgroup designated as Clade A. No species among a relatively small sample of the many species of the Clade A genus Bryconamericus were found inseminating, except Bryconamericus pectinatus. However, newly collected specimens of B. pectinatus were found to have caudal-fin squamation like that of the species of Knodus and this species is here tentatively referred to Knodus. Our investigations indicate that at least several species of Knodus, including the type species, Knodus meridae, are not inseminating, but we found two inseminating apparently new characid species that currently would be referred to Knodus. These species lack the derived anal-fin rays present in the males of K. pectinatus. Other Clade A taxa known to be inseminating, such as two species of the large genus Creagrutus, three species of Monotocheirodon (two undescribed), and the species and genera of the characid subfamily Glandulocaudinae are briefly discussed regarding possible relationships to Attonitus and Bryconadenos. The anatomical aspects of the primary and secondary sexual characteristics of Bryconadenos and Attonitus are discussed in relation to certain other inseminating characids, such as the species of Brittanichthys and Hollandichthys, that are not currently hypothesized to belong to Clade A and presumably acquired insemination independently. It is concluded that much additional data regarding the reproductive modes as well as other anatomical/physiological systems of characids currently included in and excluded from Clade A are necessary before a reasonably supported phylogeny of Clade A characids and their possible outgroup relatives can be advanced. The anal-fin gland cells of sexually active male Bryconadenos specimens are histologically indistinguishable from club cells (also called alarm substance cells) found within the skin of cypriniforms, characiforms, catfishes, and other otophysan fishes. These cells occur at the skin's surface of the anal-fin gland in male Bryconadenos where they are organized into an organ. Many other adult male characids have club cells at the anal-fin's skin surface, often associated with anal-fin hooks, but were not found organized into an organ as in Bryconadenos. We hypothesize these cells to secrete a pheromone during courtship via holocrine secretion. Males of the genera Lophiobrycon , Glandulocauda, and Mimagoniates, tribe Glandulocaudini, were found to have club cells associated with their caudal-fin organ, but no specialized mucus cells were present as found in the caudal organ of males of the glandulocaudine Corynopoma riisei, tribe Stevardiini (= Corynopomini of past authors). In this species, males have hypertrophied mucus cells hypothesized to be modified for pheromone secretion. Evidence that the derived scales and fin rays of the caudal organ of males of the tribe Glandulocaudini are not homologous with that of other tribes of the Glandulocaudinae, as this subfamily was previously recognized, is discussed and it is concluded that the members of the tribe Glandulocaudini should be recognized as a separate subfamily, the Glandulocaudinae, with possible close relationships to some other Clade A inseminating characids that lack caudal-fin organs. The remaining tribes of the former Glandulocaudinae are here included in the subfamily name Stevardiinae. Many species of these two subfamilies and some of the other inseminating Clade A characids have modified sperm cells with an elongate "binding"cytoplasmic collar and mitochondria located along and beyond the nucleus. This may be an indication of a relationship at a unique level within Clade A characids. However, further research on the derived nature and homology of the sperm cells within inseminating Clade A characids and of the caudal organs of the tribes of the Stevardiinae must be undertaken in order to utilize sperm cell features as characters for studying phylogeny. Finally, the kinds of secretory cells and gross anatomical structures in the tail organs of the stevardiine tribes need detailed research in order to better present hypotheses of phylogeny for the tribes of the Stevardiinae as well as all inseminating Clade A characids.

Riffle and pool fish communities in a large stream of southeastern Brazil

The structure of the fish communities of a pool and a rapid in the ribeirão Santa Bárbara is described. This stream of 5th order is a direct tributary of the rio Tietê in the system of the upper rio Paraná. Thirty three species, from nine families and three orders, were referred in the two mesohabitats: the pool with 31 species, and the rapid with 18. Orders Characiformes, Siluriformes, and Perciformes presented the greatest number of species in the two mesohabitats. The families Characidae and Loricariidae were the most specious, followed by Cichlidae in the pool, and by Parodontidae in the rapid. Most species were accidental, 17 in the pool, and 10 in the rapid, and only six were constant in the two mesohabitats. The greatest diversity and evenness occurred in the pool. The seasonal variation for both assemblages was high, with the pool having a high turnover of species that could be due to the proximity with main channel of the rio Tietê.

Gene mapping of 5S rDNA sites in eight fish species from the Paraíba do Sul river basin, Brazil

The use of improved cytogenetic techniques such as fluorescent in situ hybridization (FISH) has offered important methodologies for cytotaxonomic and evolutionary studies. In particular, the mapping of 5S rDNA sites has proved to be an excellent marker in the study of different organisms and, more recently, in fish. In the present work, the FISH technique was used to map the 5S rDNA sites in the chromosomes of eight neotropical fish species from the Paraíba do Sul river basin, four of these belonging to the order Characiformes, family Characidae, genus Astyanax (A. scabripinnis, A. parahybae, A. giton and A. intermedius) and four to the order Siluriformes, family Loricariidae (Neoplecostomus microps, Harttia loricariformis, Hypostomus affinis and Upsilodus sp.). Karyotype evolution aspects of the analyzed groups are discussed.

Endocytosis of horse-spleen ferritin in the black tetra, Gymnocorymbus ternetzi (Characidae: Teleostei)

The capability and capacity of various tissues in black tetra Gymnocorymbus ternetzi (Boulenger), family Characidae, to take up horse-spleen ferritin from the blood stream are described. In the head kidney from specimens injected intraperitoneally with horse-spleen ferritin, numerous large cells were tightly packed by yellow-brown granules when the period of time between injection and sacrifice was over 2 h. These cellular granules were tightly packed with Prussian blue precipitation in tissues treated with an acid ferrocyanide solution, i.e., they displayed a deep blue colour. Similarly, smaller cells were also observed in the trunk kidney, gills and peripheral connective tissue of the pancreas and spleen at this stage after ferritin injection, but they were always few in number. Yellow-brown granules or Prussian blue granules were not found in endothelial cell layers of heart and liver. We suggest that practically all clearance of the blood from foreign and scavenger macromolecules is performed by macrophages in the head kidney of the black tetra, whereas the spleen seems to function mainly as a reservoir for red blood cells in this species.

A new Eocene citharinoid fish (Ostariophysi: Characiformes) from Tanzania

ABSTRACT A single specimen of the anterior portion of a small fish was collected from the Eocene Mahenge site of Tanzania in 1996. The specimen, preserved as part and counterpart natural mold, is identified as belonging to a characiform fish, although the presence of a Weberian apparatus has not been confirmed beyond doubt. Features of the bones, such as the prominent lateral ridge on the anterodorsal corner of the opercle, the fused postcleithra 2+3, and the lack of a dentary symphyseal hinge, indicate that the fish is related to the Citharinidae and Distichodontidae. The fossil cannot be included in any known genus, and is described here as a new genus and species, Eocitharinus macrognathus. The fossil record of characiforms includes few articulated skeletons, of which only one had been reported previously from Africa, described in the family Characidae (=Alestidae).

Structure of Fish Assemblages in Amazonian Rain-Forest Streams: Effects of Habitats and Locality

Abstract We examined fish assemblage structure in three headwater rain-forest streams in the Urubu River Basin, Central Amazonia, as it relates to habitat heterogeneity. Riffles and pools, two types of stream habitat, were defined by current, depth, and substrate parameters, adjusted for Amazonian stream characteristics. We assessed species richness, composition, and abundance as they varied between riffles and pools across three similar streams. Four riffles and four pools were identified in each stream and sampled four times during 1996 and 1997. The samples yielded a total of 856 individuals of 22 species. The most abundant species were in the families Characidae, Lebiasinidae, Helogenidae, and Rivulidae. We found an interactive influence of riffle/pool habitat and stream factors on species richness, composition, and abundance. Rain-forest stream fish assemblages are structured by both habitat and stream locality.

Composição e abundância da ictiofauna na zona litorânea de um tributário, na zona de sua desembocadura no reservatório de Jurumirim, Estado de São Paulo, Brasil

Monthly collections of fishes using a trawl net were carried out from August 1996 to December 1997 with the objective of evaluating the composition and diversity of fish species in the littoral area of the transition zone between Veados Stream and Jurumirim Dam (Upper Paranapanema River, Sao Paulo State). Diversity and similarity indices of ichthyofauna at the sites were determined and correlated with abiotic factors such as dissolved oxygen, temperature, pluviometric precipitation and hydrological level. Twenty-six (26) fish species (the majority small-sized) of the family Characidae ( Tetragonopterinae and Cheirodontinae ) were registered. Representatives of the orders Siluformes, Gymnotiformes, Perciformes and Synbranchiformes occurred in lower abundance. Significant differences were found in the site diversity indices, but not in the abiotic factors. Significant correlations between the abundance of the ichthyofauna and the variations in the abiotic factors were not detected. The presence of fish larvae in the samples indicates the importance of the transition zone as a reproduction area of the fish species registered in this study

Ultrastructural aspects of the myxosporean Henneguya astyanax n. sp. (Myxozoa: Myxobolidae), a parasite of the Amazonian teleost Astyanax keithi (Characidae).

This study reports light and electron microscopical aspects of a myxosporean found in the gills of the freshwater teleost Astyanax keithi Géry, Planquete & Le Bail, 1996 (family Characidae), collected from the estuarine region of the Amazon River, near Belém, Brazil. The prevalence of infection was 23%. In interlamellar spaces of the gills, ellipsoidal whitish cyst-like plasmodia structures were present, which contained spores. The spores had a spermatozoa-like appearance (47.8 +/- 0.71 microm in total length) with a fusiform body (15.2 +/- 0.77 pm in length, 5.7 +/- 0.71 microm in width and 4.2 +/- 0.31 microm in thickness), and each of the 2 valves presented a tapering tail (32.6 +/- 1.11 microm in length). The valves surrounded a binucleate sporoplasm cell and 2 polar capsules (5.0 +/- 0.13 microm in length, 1.5 +/- 0.07 microm in width) that contained 8 to 9 coils of the polar filament. In the sporoplasm, several unique sporoplasmosomes were visible. A synoptic table of spore measurements of known Brazilian Henneguya species is presented. The spores differed from those of previously described species. Based on spore morphology, it is concluded that this species belongs to the family Myxobolidae, genus Henneguya, and that it constitutes a new species: H. astyanax n. sp.

Alterações hematológicas e histopatológicas em pacu, Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes, Characidae),

Lab. de Patol. Organismos Aquaticos Centro de Aquicultura da Unesp, Via Prof. Paulo Donato Castellane, 14884-900 Jaboticabal, Sao Paulo

Tolerance of Yolk Sac and Free-Swimming Fry of the Zebra DanioBrachydanio rerio, Black TetraGymnocorymbus ternetzi, Buenos Aires TetraHemigrammus caudovittatus, and Blue GouramiTrichogaster trichopterusto Therapeutic Doses of Formalin and Sodium Chloride

Abstract The purpose of this study was to determine the tolerance of larval fish in the families Characidae, Cyprinidae, and Belontiidae to therapeutic doses of sodium chloride and formalin. Four species of fish were included in this study: zebra danio Brachydanio rerio (also known as Danio rerio), black tetra Gymnocorymbus ternetzi, Buenos Aires tetra Hemigrammus caudovittatus, and blue gourami (also known as threespot gourami) Trichogaster trichopterus. Representative species from each family for both yolk sac fry (2–3 d old) and free-swimming fry (5–7 d old) were tested. The treatments consisted of 1 or 3 g/L sodium chloride or 12.5 or 25 mg/L formalin. Mortalities at 24 and 48 h were compared. Although 12.5–25 mg/L of formalin appears to be safe for very young zebra danio fry, therapeutic doses of salt are not recommended. Yolk sac and free-swimming fry of the blue gourami are tolerant of therapeutic doses of salt (1–3 g/L) but very sensitive to formalin. Because there are significant differences in t...

Condition factor in nine species of fish of the Characidae family in the upper Paraná River floodplain, Brazil.

The condition factor for nine species of tropical freshwater fish of the Characidae family in the upper Paraná River floodplain is described. Fish were caught over a period of 12 months (February 1993 to March 1994). Knowledge of the nine species is important for adequate management and maintenance of the biological equilibrium of the ecosystem.

Chromosome R-banding pattern and conservation of a marker chromosome in four species, genus Astyanax (Characidae, Tetragonopterinae)

Abstract The R-banding pattern obtained by 5-Bromodeoxiuridine incorporationin the chromosomes was analyzed in four species from genus Astyanax (Pisces, Characidae), A. altiparanae, A. fasciatus, A. schubarti and A. scabripinnis using specimens sampled from populations of the upper Paraná river system, in Brazil. Chromosome constitution and C-band pattern are also described forthe four species. The occurrence of chromosome homoeologies of several chromosomepairs, including a chromosome marker that is found in almost every species belonging to family Characidae was observed. These chromosome similarities may indicate a close evolutionary relationship within this group of species.

An uncommon condition for a sex chromosome system in Characidae fish. Distribution and differentiation of the ZZ/ZW system in Triportheus.

Triportheus is a neotropical freshwater Characidae fish that has a well-differentiated ZZ/ZW sex chromosome system. The W chromosome of this genus contains a large amount of heterochromatin and is smaller than the Z chromosome. This contrasts with other ZW fish systems where the W chromosome is larger in size due to increased heterochromatin. All species of Triportheus that have been studied cytologically (about 50% of the known species for this genus, from some of the major South American hydrographic basins) share this sex chromosome system, indicating a probable synapomorphic condition not present in other genera of the large Characidae family. However, while the Z chromosome appears to be largely conserved, the W chromosome shows a differential evolution with morphological differentiations not only among species, but also among populations from the same hydrographic basin, and with some species presenting a greater homology between the W and the Z chromosomes than others.

Some 20th century fish discoveries

Of the approximately 1.5 million species described to date, about 48 170 (3.2%) are vertebrates. Of these 24 618 (51%) are fishes. Amazingly, 41% of fishes are found in fresh water which makes up a negligible percentage of the water on earth. The sea accounts for 97% of all water on the planet and contains 58% of the fish species, mostly from shallow, warm-coastal areas. The families Cichlidae, Cyprinidae, Characidae, Loricariidae, and Cyprinodontidae constitute about half of all the recently described new freshwater fish species named in the period 1978–1993. The Gobiidae and Serranidae are the marine families with the largest number of recently described new species. The most new freshwater teleost names came from South America (39%), Africa (32%) and Asia (17%). New fish species continue to be described at the rate of roughly 130–160 each year. An estimated 13 775 new fish names have been proposed in this century, representing about 56% of all currently known fish species. Three species are discussed in detail to represent remarkable examples of 20th century fish discoveries: the coelacanth Latimeria chalumnae, the salamanderfish Lepidogalaxias salamandroides of Western Australia, and the megamouth shark Megachasma pelagios.

Characidiin Genus Characidium (Teleostei, Characiformes) in Southern Brazil, with Description of Three New Species

Three new species of the characidiin fish genus Characidium are described from southern Brazil. Characidium serrano sp.n., from the upper rio Uruguay drainage in the Rio Grande do Sul and Santa Catarina states, is diagnosed by the presence of unique oblique bars on the sides of the body. Characidium orientale sp.n., from the laguna dos Patos drainage, in eastern Rio Grande do Sul state, and C. occidentale sp.n., from the rio Uruguay drainage in western Rio Grande do Sul, are members of a group of species (also including C. rachovii, which has a short lateral line) diagnosed by the presence of roundish black marks on the pelvic, dorsal, anal fins; C. orientale and C. occidentale are distinguished from each other by the relative size of these marks near the anterior end of the anal fin (larger in C. occidentale), and their organization in the dorsal fin (forming a band in C. occidentale). The status of the other four species of Characidiinae (C. pterostictum, C. rachovii, C. tenue, and Characidium sp. cf. C. zebra) occurring in the area is briefly reviewed. Descrevem-se tres especies novas de peixes caracidiineos do genero Characidium ocorrentes no sul do Brazil. Characidium serrano sp.n., da bacia do alto rio Uruguai nos estados do Rio Grande do Sul e Santa Catarina, sao diagnosticados pela presenca exclusiva de barras obliquas nas laterais dos corpo. Characidium orientalesp.n., do sistema da laguna dos Patos, no leste do Estado do Rio Grande do Sul, e C. occidentale sp.n., da bacia do rio Uruguai no oeste daquele estado, sao membros de um grupo de especies (que tambem inclui C. rachovii, a qual possui linha lateral curta) diagnosticado pela presenca de manchas pretas arredondadas nas nadadeiras pelvicas, dorsal e anal; C. orientale and C. occidentale diferem no tamanho destas marcas (maiores em C. occidentale) junto a porSao anterior da nadadeira anal e sua organiza7ao na nsdadeira dorsal (formando uma faixa transversal em C. occidentale). Discute-se, tambem, a sistematica das outras quatro especies de caracidiineos (C. pterostictum, C. rachovii, C. tenue, and Characidium sp. cf. C. zebra) ocorrentes na area.