Dinaíza Abadia Rocha-Reis, Rubens Pasa, Fabiano Bezerra Menegidio, John Seymour Heslop-Harrison, Trude Schwarzacher, Karine Frehner Kavalco
Hypostomus Lacépède (1803) is the dominant genus of armored catfish (Siluriformes, Loricariidae, Hypostominae) in Brazilian rivers (Britski, 1972). This group presents a wide interspecific color and morphology variation (Oyakawa et al., 2005), which hinders the identification of some species. Likewise, the existence of various cytogenetic phenotypes, including different chromosomal numbers, karyotype formulas, and location of ribosomal genes (Rocha-Reis et al., 2020), reinforces the need for more appropriate methodologies for species identification. The Alto Paraná river basin concentrates the largest number of studies on freshwater fish in Brazil (Agostinho et al., 2007). This drainage basin is the habitat of 25 species of the genus Hypostomus (Weber, 2003), suggesting a complex evolutionary history for the taxon in this region. Hypostomus ancistroides Ihering (1911), which has a natural distribution in the basins of the rivers Tietê, Ribeira de Iguape, and Alto Paraná (Fricke et al., 2020), is considered a complex of cryptic species due to the different morphotypes found in its area. In fact, this complex of cryptic species has representatives with small morphological variations among populations, different chromosomal numbers, unique karyotype formulas for each population, polymorphisms related to the number and location of Nucleolus Organizer Regions, ribosomal DNAs, constitutive heterochromatin patterns, and even the (occasional) existence of sex chromosome systems (Rocha-Reis et al., 2020).
Rocha-Reis DA, Pasa R, Menegidio FB, Heslop-Harrison JS, Schwarzacher T and Kavalco KF (2020) The Complete Mitochondrial Genome of Two Armored Catfish Populations of the Genus Hypostomus (Siluriformes, Loricariidae, Hypostominae). Front. Ecol. Evol. 8:579965. doi: 10.3389/fevo.2020.579965