Abstract
Fishes of the Loricariidae family, known as “cascudos”, constitute an endemic group in Neotropical freshwaters. In this study, were cytogenetically examined two species of Loricariidae (Pterygoplichthys anisitsi Eigenmann & Kennedy, 1903 and Farlowella amazonum (Günther, 1864) belonging to Hypostominae and Loricariinae subfamilies respectively) from Iguatemi River. Our study provide the first description regarding C-band and fluorochromic analysis in Farlowella amazonum. In Farlowella amazonum, diploid number was 58 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric regions of some chromosomes and large subtelomeric blocks were evidenced on the long arm of the pair 27, being this region CMA3+/DAPI-. The Pterygoplichthys anisitsi showed diploid number equal 52 chromosomes, with single Ag-NOR and heterochromatic blocks in centromeric and telomeric regions of some chromosomes and conspicuous large telomeric blocks on the long arm of the pair 10, being this region CMA3+/DAPI-. The results show that karyotype formula is nonconservative in Pterygoplichthys anisitsi and Farlowella amazonum.
Highlights
Fishes of the Loricariidae family, known as “cascudos”, constitute an endemic group in Neotropical freshwaters and are morphologically characterised by the body covered by several rows of plates and a ventral mouth with lips forming a sucker (Graça and Pavanelli 2007)
Evident bitelomeric markings were present in the pairs 10 and 15, and conspicuous large telomeric blocks were present on the long arm of the pair 10 and interstitial blocks were evidenced on the long arm pair 9, adjacent to the Ag-NOR region (Fig. 2b)
DAPI staining revealed pale regions corresponding to telomeric regions on the long arm of the pair 10, coinciding with chromomycin A3 (CMA3)+ region, confirming that those regions are poor in AT
Summary
Fishes of the Loricariidae family, known as “cascudos”, constitute an endemic group in Neotropical freshwaters and are morphologically characterised by the body covered by several rows of plates and a ventral mouth with lips forming a sucker (Graça and Pavanelli 2007) This family includes 887 valid species in seven subfamilies: Hypoptopomatinae, Loricariinae, Hypostominae, Neoplecostominae, Lithogeninae, Delturinae, and Ancistrinae (Eschmeyer and Fong 2014). Ancistrinae (as a tribe Ancistrini) was considered as a tribe in the family Hypostominae along with Hypostomini, Rhinelepini, Pterygoplichthini, and Corymbophanini (Armbruster 2004) According to the latter author, the Pterygoplichthini is composed by genera and species groups: Pterygoplichthys Gill, 1858, Hemiancistrus annectens group, being that Liposarcus Günther, 1864, and Glyptoperichthys Weber, 1991 are recognized as synonyms of Pterygoplichthys. For tribe Pterygoplichthini cytogenetic studies are scarce, which all species presenting a diploid number of 52 chromosomes, as observed in Pterygoplichthys joselimaianus (Weber, 1991) (Oliveira et al 2006), Pterygoplichthys anisitsi Eigenmann & Kennedy, 1903 (cited as Liposarcus anisitsi – Alves et al 2006), Pterygoplichthys multiradiatus (Hancock, 1828) (cited as Liposarcus multiradiatus – Alves et al 2006) and Pterygoplichthys gibbiceps (Kner, 1854) (cited as Glyptoperichthys gibbiceps – Alves et al 2006)
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