Cytogenetic characterization of Hollanda-Carvalho & Weber, 2004 from the Teles Pires River, southern Amazon basin: evidence of an early stage of an XX/XY sex chromosome system.

In the present study, we analyzed individuals of (Loricariidae) collected from the Teles Pires River, southern Amazon basin, Brazil. has a diploid chromosome number of 2n = 64 and a karyotype composed of 12 metacentric (m), 22 submetacentric (sm), 14 subtelocentric (st), and 16 acrocentric (a) chromosomes, with a structural difference between the chromosomes of the two sexes: the presence of a block of heterochromatin in sm pair No. 26, which appears to represent a putative initial stage of the differentiation of an XX/XY sex chromosome system.

Chromosomal Diversity of Three Species of Hypostomus Lacépède, 1803 (Siluriformes, Loricariidae), from the Paraná River Basin, Brazil: A Species Complex in Hypostomus ancistroides Reinforced by a ZZ/ZW Sex Chromosome System.

Hypostomus shows wide morphological patterns, corroborated by great chromosomal diversity that has suggested the existence of new species, especially from small tributaries. Cytogenetic analysis has contributed to estimate a cryptic diversity providing important data for taxonomic and evolutionary studies. Cytogenetic techniques were carried out on species from a small tributary of Ivaí River, Keller River (upper Paraná River basin): Hypostomus aff.

Diversity of Sex Chromosome Systems in Ancistrini (Loricariidae, Hypostominae): ZZ/ZW in Ancistrus taunayi Miranda Ribeiro, 1918.

The karyotype of the Ancistrini catfish Ancistrus taunayi was analyzed by conventional (Giemsa staining, AgNOR staining and C-banding) and molecular cytogenetic (5S and 18S rDNA-FISH) methods. The diploid chromosome number was 2n = 50 (22 metacentrics + 10 submetacentrics + 10 subtelocentrics + 8 acrocentrics) for both sexes. A single NOR-bearing acrocentric chromosome pair (No.

Karyotypic diversity of the armoured catfish genus Hypostomus (Siluriformes: Loricariidae) in the context of its occurrence and distribution.

This study taxonomically reviewed the specimens studied by Artoni & Bertollo (1996) and assimilated species of Hypostomus into three groups according to their cytogenetic characteristics, vagility and occurrence environments.

Cytogenetic characterization of species of the family Heptapteridae (Teleostei: Siluriformes) from the Cuiabá and Ivaí River Basins, Brazil.

We cytogenetically characterized three species of Heptapteridae (Pimelodella sp, Pimelodella taenioptera, and Imparfinis schubarti) by investigating the distribution of constitutive heterochromatin and nucleolar organizer regions by silver nitrate impregnation (Ag-NOR) and fluorescence in situ hybridization. Pimelodella sp showed had a diploid number (2n) = 46 chromosomes, 26m + 10sm + 10st, and FN = 92; P. taenioptera, 2n = 52 chromosomes, 26m + 22sm + 4st, and FN = 104; and I.