Chromosome characterization and biogeographic relations among three populations of the driftwood catfish Parauchenipterus galeatus (Linnaeus, 1766) (Siluriformes: Auchenipteridae) in Brazil

Abstract

The present study employed basic and molecular cytogenetic methods to characterize three populations of Parauchenipterus galeatus from the basins of the Paraná and São Francisco Rivers, and a region of connection between the two basins. Although the diploid number was equal to 58 chromosomes, variations in karyotype formula were detected among the populations. B chromosomes were detected only in the population from the São Francisco River. Heterochromatin was located in the terminal position in almost all the chromosomes and in the pericentromeric position in some acrocentric chromosomes in the three populations. A single nucleolus organizer region was detected by silver nitrate and 18S rDNA-fluorescent in situ hybridization in the short arm of one subtelocentric pair in the three populations, varying only in the chromosome pair bearing this site. The 5S rDNA sites were located in two submetacentric chromosome pairs in the three populations, varying only in the chromosome pairs bearing these sequences. Classic and molecular chromosome markers, along with the context of the natural history of the formation of hydrographic basins, ecological aspects, and the geographic isolation of populations between hydrographic basins and within the same basin, were important contributions to the discussion on possible biogeographic relations among the populations of Parauchenipterus galeatus.

The role of chromosomal fusion in the karyotypic evolution of the genus Ageneiosus (Siluriformes: Auchenipteridae)

“…The available data in the literature for hybridization with 18S rDNA probe for Auchenipteridae are restricted to Parauchenipterus galetaus (Lui et al, 2009;Lui et al, 2010) and Glanidium ribeiroi (Fenocchio et al, 2008), which always confirmed the results presented by silver impregnation of only one marked pair. According to Ravedutti & Júlio Jr. (2001), simple NORs seem to be a feature of Auchenipteridae.…”

“…), whereas another population of this species and Ageneiosus atronasus (cited as A. brevifilis), both from Solimões River (Fenocchio & Bertollo, 1992), and Ageneiosus brevis and Ageneiosus ucayalensis, both from Catalão Lake (Santos & Nakayama, 2011), have the diploid number of 56 chromosomes. However, species from other genera that were cytogenetically studied, as Glanidium ribeiroi, Parauchenipterus galeatus and Auchenipterus osteomystax (cited as A. nuchalis) have 58 chromosomes (Fenocchio & Bertollo, 1992;Ravedutti & Júlio Jr., 2001;Fenocchio et al, 2008;Lui et al, 2009;Lui et al, 2010).…”

Karyotypic variation of Glanidium ribeiroi Haseman, 1911 (Siluriformes, Auchenipteridae) along the Iguazu river basin

“…Most species of Auchenipteridae, analyzed by C-banding of genera Ageneiosus, Auchenipterus, Glanidium, Parauchenipterus and Tatia (Ravedutti and Júlio Junior, 2001;Fenocchio et al, 2008;Lui et al, 2009Lui et al, , 2010Lui et al, , 2013a; present paper), presented the heterochromatin as preferentially located in terminal regions with pale blocks, which seems to be a characteristic of the family. One prominent heterochromatic block was observed in the short arm of the pair where the NORs are located in the species of this study.…”

“…The chromosomal studies related to the Iguazu river basin include 24 nominally valid species, and at least 10 others that had not yet been described (Kantek et al, 2007). Regarding Auchenipteridae, the chromosomal studies are still scarce, comprising only species of the genera Ageneiosus, Auchenipterus, Glanidium, Parauchenipterus and Tatia (Fenocchio and Bertollo, 1992;Ravedutti and Júlio Junior, 2001;Fenocchio et al, 2008;Lui et al, 2009Lui et al, , 2010Lui et al, , 2013a. Regarding the Iguazu river, there are only two valid species of this family, Tatia jaracatia (Pavanelli and Bifi, 2009) and Glanidium ribeiroi, both having 58 chromosomes.…”

Cytogenetics of the Thorny Catfish <b><i>Trachydoras paraguayensis</i></b> (Eigenmann &amp; Ward, 1907), (Siluriformes, Doradidae): Evidence of Pericentric Inversions and Chromosomal Fusion

“…Irrespective of this polymorphism, the interstitial position of 5S rDNA sites found in T . paraguayensis was also described for Auchenipteridae species, such as Parauchenipterus galeatus [Lui et al, 2010], A. inermis [Lui et al, 2013a], Tatia jaracatia , and T. neivai [Lui et al, 2013b]. 205 Despite the fact that 2n = 58 is considered to be an ancestral trait in Doradidae, the variations in karyotype structures suggest that chromosomal rearrangements are involved in chromosomal differentiation in this family.…”