Karyotype description of possible new species of the Hypostomus ancistroides complex (Teleostei: Loricariidae) and other Hypostominae

Kátia Sayuri Endo,Luiz Ricardo De Souza Paiva,Claudio Henrique Zawadzki,Emanuel Ricardo Monteiro Martinez,Horácio Ferreira Júlio Júnior

doi:10.4025/actascibiolsci.v34i2.9318

Kátia Sayuri Endo, Luiz Ricardo De Souza Paiva + Show 3 more

Open Access

https://doi.org/10.4025/actascibiolsci.v34i2.9318

Copy DOI

Abstract

Cytogenetic analyses were performed in four species of the Hypostominae subfamily, three from Hypostomus (Hypostomini) genus and Rhinelepis aspera (Rhinelepini). Three populations of Hypostomus ancistroides were analyzed, which had 2n=68 chromosomes, but presented different karyotype formulas. Hypostomus regani and H. strigaticeps , both from Ivai river, showed 2n=72 chromosomes with two distinct cytotypes. In turn, R. aspera of the upper Parana river basin presented 2n=54 chromosome. Multiple Nucleolar Organizer Regions (NORs) have been evidenced by silver nitrate staining in species of Hypostomus and single NOR in R. aspera . The observed variation in the chromosome number and the marked variability in karyotype formulas and NORs reveal a certain amount of karyotype variation in the genus Hypostomus suggesting the probable existence of cryptic species with independent chromosome traits. Therefore, our data can be of great value in discriminating species and understanding their chromosomal evolution.

Highlights

Siluriformes is an extremely large, diverse and widely distributed order of fish inhabiting tropical regions around the world (FERRARIS, 2007; TEUGELS, 1996)
Cases of sex chromosomes were found in the literature for some Hypostominae, as ZZ/ZW in Hypostomus sp. (ARTONI et al, 1998) and XX/X0 in Ancistrus sp. 1 (ALVES et al, 2006), which was not observed in this study, showing that chromosomal changes related to gender/sex should be a variable character in the group
Differences in karyotype formulas have been described for other populations of H. ancistroides by Michele et al (1977), Artoni and Bertollo (1996) and Alves et al (2006) (Table 2)

Summary

Introduction

Siluriformes is an extremely large, diverse and widely distributed order of fish inhabiting tropical regions around the world (FERRARIS, 2007; TEUGELS, 1996). The number of species within Siluriformes is about 3100 and may be even higher (FERRARIS, 2007; NELSON, 2006; REIS et al, 2003; TEUGELS, 1996). Among the Siluriformes, the family Loricariidae has around 680 species, distributed into seven subfamilies: Delturinae, Hypoptomatinae, Loricariinae, Hypostominae, Neoplecostominae, Lithogeneinae and Otothyrinae (CHIACHIO et al, 2008; REIS et al, 2003, 2006). Armbruster (2004) proposes Ancistrini and Hypostomini as tribes of the subfamily Hypostominae and created three new tribes in this subfamily: Corymbophanini, Pterygoplichthini, Rhinelepini. He suggested the removal of Delturus, Hemipsilichthys, Isbrueckerichthys, Kronichthys, Pareiorhina and Upsilodus from the subfamily Hypostominae. Armbruster (2004) recognized the genus Hypostomus as the only representative of Hypostomini

Methods

Results

Conclusion