Comparative cytogenetics of two species of genus Scobinancistrus (Siluriformes, Loricariidae, Ancistrini) from the Xingu River, Brazil

By

Cardoso, Adauto Lima
Sales, Karline
Nagamachi, Cleusa
Pieczarka, Julio
Noronha, Renata

Type

Article

Date of Publication

2013

Original Publication

Comparative cytogenetics : international journal of plant & animal cytogenetics, karyosystematics and molecular systematics

Volume

7

Series / Issue

Issue: 1

Pages

43-51

Subjects

chromosome rearrangements , karyotypic divergence , sympatry

Contributed by

Pensoft Publishers

Language

English

Published by

St. Petersburg, Russia [Published] with technical support of Zoological Institute RAS [2007]-

Identifiers

DOI: https://doi.org/10.3897/compcytogen.v7i1.4128

 

Abstract

The family Loricariidae encompasses approximately 800 species distributed in six subfamilies. The subfamily Hypostominae consists of five tribes; of them, the tribe Ancistrini is relatively diverse, but it is not well known from the cytogenetic point of view. Genus Scobinancistrus Isbrücker et Nijssen, 1989, which is part of the tribe Ancistrini, has two species that occur in sympatry in the Xingu River, Brazil. In this work, we performed the first karyotypic characterizations of these two species and sought to identify the processes involved in their karyotypic evolution. Chromosomal preparations were subjected to Giemsa staining, silver nitrate impregnation, C-banding, CMA3 staining, DAPI staining, and FISH (fluorescence in situ hybridization) with 18S rDNA and telomeric probes. We found that S. aureatus Burgess, 1994 and S. pariolispos Isbrücker et Nijssen, 1989 shared the diploid number, 2n=52, but differed in their karyotypic formulae (KFs), distribution of constitutive heterochromatin (CH), and the localizations of their nucleolus organizer regions (NORs), which were found on the interstitial and distal regions of the long arm of chromosome pair 3 in S. aureatus and S. pariolispos respectively. We suggest that these interspecific variations may have arisen via paracentric inversion or transposition of the NOR. The karyotypic differences found between these two Scobinancistrus species can be used to identify them taxonomically, and may have functioned as a mechanism of post-zygotic reproductive isolation during the speciation process.