Karyotype description of two species of Hypostomus (Siluriformes, Loricariidae) of the Planalto da Bodoquena, Brazil

Abstract

ABStRACt. Hypostomus sp 3-Córrego Salobrinha NUP 4247 and Hypostomus sp 2-Rio Perdido NUP 4249, collected in the Planalto da Bodoquena, Paraguay River basin, Brazil, were characterized cytogenetically. Hypostomus sp 3-Córrego Salobrinha showed two modal numbers. This polymorphism consists of the presence of two extrachromosomes. It was not possible to define the diploid number in four specimens, where cell lineages had 2n = 83 and 2n = 84 chromosomes in one individual, and 2n = 82, 2n = 83 and 2n = 84 chromosomes in the others. These results reveal the existence of a genetic mosaic due to the occurrence of one or two extrachromosomes in this species. Hypostomus sp 2-Rio Perdido NUP 4249 showed a 2n = 84, FN = 106 with size heteromorphism in one pair of chromosomes stained with AgNO 3 . In both species, C banding showed a pattern of heterochromatin distribution with a few small bands in the centromeric and pericentromeric regions coinciding with chromomycin A 3 staining. Until now, the major diploid number for the genus Hypostomus was 2n = 80, but the species studied here had chromosomes that in- creased this number and the variation for this genus. Our results are also the first cytogenetic data on Hypostomus from the Paraguay River basin.

Karyotype structure of Hypostomus cf. plecostomus (Linnaeus, 1758) from Tapajós River basin, Southern Amazon: occurrence of sex chromosomes (ZZ/ZW) and their evolutionary implications

“…The standard C band observed in H. cf. plecostomus with a few conspicuous blocks on the long arm of the chromosome as well as on the short arms of other chromosomes, was also found in other species of the genus, such as H. affinis (Kavalco et al, 2004), H. nigromaculatus (Rubert et al, 2008), and H. cochliodon (Cereali et al, 2008). This corroborates the results of Artoni and Bertollo (1996) and Kavalco et al (2004), who reported that Hypostomus has relatively little constitutive heterochromatin.…”

“…With the expansion of karyotypic data from this genus, its diversity has been further confirmed by different authors (Alves et al, 2006;Cereali et al, 2008;Rubert et al, 2011;Bueno et al, 2012Bueno et al, , 2013. In addition, hypotheses of phylogenetic relationships of the genus Hypostomus, based on taxonomic and molecular analysis (from mitochondrial DNA sequences) allowed some groupings with in this genus (Montoya-Burgos, 2003).…”

“…The diploid number in Hypostomus was reported to vary between 2n = 54 chromosomes in H. plecostomus (Muramoto et al, 1968) and 2n = 84 chromosomes in Hypostomus sp. 2 (Cereali et al, 2008). However, Artoni and Bertollo (2001) considered that the species with high diploid number are probably more derived than those with 2n = 54 and that high diploid number was the result of chromosomal rearrangements as centric fissions.…”

Chromosomal diversity in Hypostomus (Siluriformes, Loricariidae) with emphasis on physical mapping of 18S and 5S rDNA sites

“…This genus is known for its wide degree of chromosome diversification (Artoni and Bertollo, 2001;Mendes-Neto et al, 2011;Bueno et al, 2012), with 2n ranging from 54 chromosomes in H. plecostomus (Muramoto et al, 1968) to 84 chromosomes in Hypostomus sp 2 (Cereali et al, 2008). Nevertheless, H. plecostomus could be a case of misidentification and could belong to another Loricariidae genus.…”

“…According to Reis et al (2006), this group is subdivided into six subfamilies: Loricariinae, Hypoptopomatinae, Hypostominae, Neoplecostominae, Lithogeninae, and Delturinae. In Hypostominae, the diploid number (2n) varies from 34 chromosomes in Ancistrus cuiabae (Mariotto et al, 2011) to 84 chromosomes in Hypostomus sp 2 (Cereali et al, 2008). Most cytogenetic studies show great variability in some chromosome features; however, molecular analyses, such as physical mapping of ribosomal genes, have been done for only a small number of species (Mariotto et al, 2011;Mendes-Neto et al, 2011;Rubert et al, 2011;Ziemniczak et al, 2012;Traldi et al, 2012).…”