First Karyotypic Insights into Potamotrygon schroederi Fernández-Yépez, 1958: Association of Different Classes of Repetitive DNA.

Introduction: Currently, there are 38 valid species of freshwater stingrays, and these belong to the subfamily Potamotrygoninae. However, cytogenetic information about this group is limited, with studies mainly using classical techniques, Giemsa, and C-banding.

Methods: In this study, we used classical and molecular cytogenetic techniques - mapping of 18S and 5S rDNA and simple sequence repeats (SSRs) - in order to investigate the karyotypic composition of Potamotrygon schroederi and reveal the karyoevolutionary trends of this group.

Karyotypic variation of two populations of the small freshwater stingray Potamotrygon wallacei Carvalho, Rosa & Araújo 2016: A classical and molecular approach.

Potamotrygoninae comprises a group of Neotropical fishes with an ancient relationship with marine environments. In the last few years, 11 new Potamotrygon species were described, including Potamotrygon wallacei Carvalho, Araújo e Rosa 2016. Cytogenetic data about this species are limited to classical markers (Giemsa, C-Banding and Ag-NOR techniques), these studies highlighted a rare sexual chromosome system XX/X0 with males presenting 67 chromosomes and females 68 chromosomes.

Chromosomal rearrangements and the first indication of an ♀X X X X /♂X X Y sex chromosome system in Rineloricaria fishes (Teleostei: Siluriformes).

Rineloricaria is the most diverse genus within the freshwater fish subfamily Loricariinae, and it is widely distributed in the Neotropical region. Despite limited cytogenetic data, records from southern and south-eastern Brazil suggest a high rate of chromosomal rearrangements in this genus, mirrored in remarkable inter- and intraspecific karyotype variability. In the present work, we investigated the karyotype features of Rineloricaria teffeana, an endemic representative from northern Brazil, using both conventional and molecular cytogenetic techniques.

Cryptic Diversity in the Terminal Portion of the Chromosomes of the Dogtooth Characins, Family Cynodontidae (Ostariophysi: Characiformes).

The chromosomes of the dogtooth characins, fish species of the family Cynodontidae, have only a relatively small amount of heterochromatin, including the terminal portion. Curiously, in the cynodontid , the terminal portion is rich in repetitive DNAs, including transposable retroelements and microsatellite sequences. Given this, this study investigated the composition of the terminal portion of the chromosomes of two cynodontid species ( and ), to compile a database for the evaluation of all three cynodontid genera, and in particular, verify the possible tendency for the accumulation of repetitive DNAs in the terminal portion of the chromosomes of , , and The 1, 3, and 6 transposable retroelements and the (CA) (GA), (GATA), (GACA), (CAT), and (CAC) microsatellite motifs are found primarily in the terminal portion of the chromosomes of the species analyzed in this study, except , which has no evidence of the presence of or through the fluorescent hybridization technique.

Cytogenetic Analysis of Panaqolus tankei Cramer & Sousa, 2016 (Siluriformes, Loricariidae), an Ornamental Fish Endemic to Xingu River, Brazil.

Despite conservation of the diploid number, a huge diversity in karyotype formulae is found in the Ancistrini tribe (Loricariidae, Hypostominae). However, the lack of cytogenetic data for many groups impairs a comprehensive understanding of the chromosomal relationships and the impact of chromosomal changes on their evolutionary history. Here, we present for the first time the karyotype of Panaqolus tankei Cramer & Sousa, 2016.

Comparative cytogenetic of six species of Amazonian Peacock bass (, Cichlinae): intrachromosomal variations and genetic introgression among sympatric species.

Cytogenetic data for the genus Bloch et Schneider, 1801 are still very limited, with only four karyotype descriptions to date. The sum of the available cytogenetic information for species, points to a maintenance of the diploid number of 48 acrocentric chromosomes, considered a typical ancestral feature in cichlids. In the current study, we performed molecular and classical cytogenetic analyses of the karyotype organization of six species of , the earliest-diverging genus of Neotropical cichlids.