Karyotypic relationships among the tribes of Hypostominae (Siluriformes: Loricariidae) with description of XO sex chromosome system in a Neotropical fish species

Abstract

The family Loricariidae, with about 683 species, is one the largest fish families in the world. The subfamily Hypostominae was recently reviewed and is now divided in five tribes. With the main objective of contributing to a better understanding of the relationships of the members of the subfamily Hypostominae, cytogenetic analyses were conducted in seven species (three Hypostomini, three Pterygoplichthini and two Ancistrini) from Brazil and Venezuela. In Pterygoplichthini, all species show 2n = 52 chromosomes. In Hypostomini Hypostomus ancistroides has 2n = 68, H. regani 2n = 72 and Hypostomus goyazensis 2n = 72 chromosomes. In Ancistrini Ancistrus n. sp. 1 has 2n = 39/40 with a sex chromosome system of the type XX/X0, which is a novelty for neotropical fishes, and Ancistrus n. sp. 2 has 2n = 52 chromosomes. Six species have single Ag-NORs and two multiple Ag-NORs. The possible cytogenetic relationships among the species of Hypostominae are discussed.

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

“…Karyotype variations with conservation of the 2n over distinct populations of the same species are common in Hypostomus (Artoni and Bertollo, 1996;Alves et al, 2006;MendesNeto et al, 2011;Rubert et al, 2011). We found this situation in H. ancistroides and H. nigromaculatus, species that are widespread in Brazilian basins.…”

“…We found this situation in H. ancistroides and H. nigromaculatus, species that are widespread in Brazilian basins. All populations of H. ancistroides and H. nigromaculatus that have been studied showed 2n = 68 chromosomes (Artoni and Bertollo, 1996;Alves et al, 2006;Rubert et al, 2011) and 76 chromosomes (Rubert et al, 2008), respectively, with differences in karyotype formulae, heterochromatic pattern and NOR location. According to Bueno et al (2012), in addition to the centric fissions, pericentric and paracentric inversions also have an important role in karyotype diversification of Hypostomus, which could explain these population differences.…”

“…According to Alves et al (2006), multiple NORs in terminal position are common in species of Hypostomus, but the simple NOR condition is also observed in some species of this genus. The variability of this feature in this group is obvious, contributing to its chromosome diversity.…”

Diversity and chromosomal evolution in the genus Ancistrus Kner, 1854 (Loricariidae: Ancistrini) from three hydrographic basins of Mato Grosso State, Brazil

“…It also differs from closely related taxonomic groups, like most species analyzed in the subfamily Hypoptopomatinae (Andreata et al, 1992(Andreata et al, , 1993(Andreata et al, , 2006 and in the tribe Pterygoplichthini (Alves et al, 2006).…”

Cytogenetic characterization of Devario aequipinnatus (McClelland, 1839) and Devario yuensis (Arunkumar and Tombi, 1998) (Cypriniformes: Cyprinidae) from Manipur, northeast India

“…Similarly, sex chromosomes were indistinguishable in several cyprinid fishes reported so far Kılıç-Demirok and Ünlü, 2001;Kilic-Demirok and Ünlü, 2004;Esmaeili et al, 2007Esmaeili et al, , 2008Esmaeili et al, , 2009Esmaeili et al, , 2010Kalbassi et al, 2008). The occurrence of cytologically differentiated sex chromosomes in a large number of living marine fish species appears to be rare (Galleti et al, 2000), although it has been described in some catfishes (Alves et al, 2006) and in platyfish (Devlin and Nagahama, 2002).…”