Constitutive heterochromatin heteromorphism in the Neotropical armored catfish (Ihering, 1905) (Loricariidae, Hypostominae) from the Paraguay River basin (Mato Grosso do Sul, Brazil).

A cytogenetic analysis based on the integration of a number of different chromosomal methodologies, including chromosome microdissection was carried out to characterize the chromosomally polymorphic population from the Paraguay River basin, state of Mato Grosso do Sul in Brazil. All specimens had 2n=72 (FN=116) but two distinct karyotype formulas: karyomorph A (12m+14sm+18s+28a) and karyomorph B (13m+14sm+17st+28a). Karyomorph A and B differed only for pair 19 that consisted of two subtelocentrics in karyomorph A and a large metacentric and a subtelocentric in karyomorph B.

Hidden Diversity in the Populations of the Armored Catfish Kner, 1854 (Loricariidae, Hypostominae) from the Paraná River Basin Revealed by Molecular and Cytogenetic Data.

Only one species of armored catfish, Valenciennes 1836, has been historically described in the basin of the Paraná River, from Misiones (Argentina). However, the ample variation found in the morphology and coloration of the populations sampled in the tributaries of the Brazilian state of Paraná makes it difficult to establish the real taxonomic status and evolutionary history of the specimens, suggesting that is not the only species found in this basin. By combining data on mitochondrial DNA (COI gene) and chromosomal markers from different populations, totaling 144 specimens, in the tributaries of the Paraná, and specimens from Misiones (type-locality of ), we detected five distinct evolutionary lineages.

Cytogenetic data on sp. (Siluriformes, Loricariidae) of the Paraguay River basin (MS) sheds light on intrageneric karyotype diversification.

Kner, 1854 is a diverse catfish genus, currently comprising 66 valid species, but karyotype data were recorded for 33 species, although only ten have their taxonomic status defined. Considerable karyotype diversity has been found within this genus, with 2n varying from 34 to 54 and structural variability including heteromorphic sex chromosomes. In many cases, uncertainty on the taxonomic status of the study populations hampers reliable interpretation of the complex chromosomal evolutionary history of the group.

Chromosomal polymorphism in Rineloricaria lanceolata Günther, 1868 (Loricariidae: Loricariinae) of the Paraguay basin (Mato Grosso do Sul, Brazil): evidence of fusions and their consequences in the population.

Rineloricaria is the most species-rich genus of the Loricariinae (armored catfish) with 65 valid species. However, the karyotype structure is known only for eight species in this group. This study provides cytogenetic data for Rineloricaria lanceolata collected from the upper Paraguay basin (Mato Grosso do Sul).