Allozyme differentiation of two populations of the genus Neoplecostomus Eigenmann & Eigenmann, 1888 (Teleostei, Loricariidae) from the upper Paraná River basin, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Genetic diversity in Egeria densa and E. najas in Jupia Reservoir, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chromosome evolution in fish: sex chromosome variability in Eigenmannia virescens (Gymnotiformes : Sternopygidae)

New data are presented on the sex chromosomes of the fish species Eigenmannia virescens (Gymnotiformes, Sternopygidae). A new finding, involving the occurrence of ZZ/ ZW sex chromosomes, is described in specimens sampled from the Sao Francisco and Amazon river basins in Brazil. All individuals had a chromosome number of 2n = 38. The homologs of the sex chromosome pair from the Sao Francisco river basin sample differed only in their morphology, while those from the Amazonian sample differed both in morphology and heterochromatin pattern. A possible model for the evolution of the sex chromosomes in E virescens is proposed, including data from populations from the Parana (Brazil) river basin, in which male heterogamety has already been described. The occurrence of different sex chromosome systems in species and populations of the neotropical freshwater fish fauna is discussed. Copyright (C) 2002 S. Karger AG, Basel.

New occurrence of microchromosomes B in Moenkhausia sanctaefilomenae (Pisces, Characidae) from the Parana River of Brazil: analysis of the synaptonemal complex

The Moenkhausia sanctaefilomenae specimens showed a karyotype consisting of 2n = 50 chromosomes with 12 metacentrics, 36 submetacentrics and two subtelocentrics. In addition to the basic karyotype, all the males specimens have cells ranging from zero to two B microchromosomes in mitotic metaphases. These chromosomes were not observed in the female specimens. C-band analysis showed a distribution pattern of characteristic heterochromatin with interstitial and centromeric blocks. However, the B chromosomes were faintly stained with C-banding and were not fluorescent with CMA(3) staining. The meiotic studies showed the formation of bivalents in metaphase I and in pachytene under an optical microscope. Through synaptonemal complex analysis with an electron microscope, the pachytene showed 25 bivalents completely paired and a small bivalent corresponding to the B chromosomes. In the same preparation, one of the B chromosomes was observed in a univalent form. on the basis of pairing behavior and morphology it is assumed that B chromosomes of M. sanctaefilomenae show homology between them and their evolutionary aspects are discussed.

A new Moenkhausia Eigenmann, 1903 (Ostariophysi: Characiformes) from Chapada Diamantina, rio Paraguaçu Basin, Bahia, Northeastern Brazil

Moenkhausia diamantina, nova espécie, é descrita de tributário do rio Paraguaçu, BA, nordeste do Brasil. Esta espécie é distinguida das demais congêneres por caracteres relacionados ao padrão de coloração do corpo, pela presença de escamas na linha mediana pré-dorsal e número de raios da nadadeira anal.

Detection of hybrids and genetic introgression in wild stocks of two catfish species (Siluriformes: Pimelodidae): The impact of hatcheries in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Molecular systematic and historical biogeography of the armored Neotropical catfishes Hypoptopomatinae and Neoplecostominae (Siluriformes: Loricariidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

5S rDNA chromosomal mapping and COI sequence analysis reveal differentiation among distinct populations of a characid fish Serrapinnus notomelas

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Deep barcode divergence in Brazilian freshwater fishes: the case of the Sao Francisco River basin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Description of a new species of Pareiorhina (Siluriformes: Neoplecostominae) from Rio Sao Francisco basin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A new species of Hyphessobrycon (Characiformes : Characidae) from rio Portuguesa, rio Orinoco basin, Venezuela

A new species of Hyphessobrycon is described from tributaries of the rio Portuguesa, rio Orinoco Basin, Venezuela. The new species is diagnosed from congeners by the presence of two large hooks on each side of the anal fin in adult males ( processes of last unbranched and first branched anal-fin rays), distal third of caudal-fin black except for its distal tips ( which are hyaline), anal-fin rays v, 19-21, and dorsal-fin rays ii, 8. Comments on its generic status and putative relationships are provided.

Genetic variability of two populations of Pseudoplatystoma reticulatum from the Upper Paraguay River Basin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Length-weight relationships for 20 species collected in the Jurumirim reservoir (Paranapanema Basin, Brazil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

A new species of Ctenobrycon Eigenmann, 1908 (Characiformes: Characidae) from the rio Orinoco basin, Venezuela

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

DNA barcodes discriminate freshwater fishes from the Paraiba do Sul River Basin, São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)