Mapping of Repetitive Sequences in Brachyhypopomus brevirostris (Hypopomidae, Gymnotiformes) from the Brazilian Amazon
2024
Paula Pinto Rodrigues | Milla de Andrade Machado | Ananda Marques Pety | Willam Oliveira da Silva | Julio Cesar Pieczarka | Cleusa Yoshiko Nagamachi
Brachyhypopomus (Hypopomidae, Gymnotiformes) is a monophyletic genus consisting of 28 formally described species. Karyotypic data are available for 12 species. The same karyotype is described for two species (B. brevirostris and B. hamiltoni), as well as different karyotypes for the same species from distinct locations (B. brevirostris). In this context, B. brevirostris may constitute a cryptic species complex. Thus, in the present study, we analyzed the karyotype of B. brevirostris, from Santaré:m, Pará:, and Tefé:, Amazonas, using classical cytogenetics (conventional staining and C-banding) and molecular techniques (fluorescence in situ hybridization using 18S rDNA, 5S rDNA, U2 snRNA, and telomeric probes). The results show that samples from both locations present 2n = 38, with all chromosomes being acrocentric (FC = 38a). In both populations, 18S rDNA sequences are present on only one pair of homologous chromosomes and telomeric sequences occur only at the ends of the chromosomes. In the Tefé: sample, the 5S rDNA occurs in two pairs, and the U2 snRNA in three pairs. These results are the first descriptions of these sequences for B. brevirostris samples from the Tefé: locality, as well as the first karyotypic description for the Santaré:m locality. Future cytotaxonomic studies of this genus can benefit from these results.
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