Cytogenetic studies in six species of Scinax (Anura, Hylidae) clade Scinax ruber from northern and northeastern Brazil.

Lídia Nogueira,Sérgio Siqueira,Iracilda Sampaio,Paulo Roberto Antunes De Mello Affonso,Juliani Bruna Zanoni,Mirco Solé

doi:10.1590/s1415-4757382220140280

Abstract

Scinax species are still underrepresented in cytogenetic studies, mainly with respect to populations from northeastern and northern Brazil. In this study, we provide new chromosomal information on Scinax boesemani, S. camposseabrai, S. garbei, S. pachycrus, S. trilineatus and S. x-signatus, all belonging to clade S. ruber. They were collected at two locations in the Caatinga biome (northeastern Brazil) and at one in the Amazon (northern Brazil) biomes. Chromosomes were analyzed by conventional staining, C-banding, Ag-NOR staining, and fluorochrome staining. All species shared a modal diploid value of 2n = 24 and fundamental arm number (FN) of 48. Moreover, both chromosomal size and morphology were similar to other species in this Scinaxclade. C-banding revealed centromeric heterochromatin in all species, along with terminal species-specific C-bands in some species. Active nucleolar organizer regions (Ag-NORs) were identified at 11q in most species, except for S. boesemani and S. garbei (Ag-NORs at interstitial region of 8q). Differing from most anurans, GC-rich regions were not restricted to NORs, but also coincident with some centromeric and terminal C-bands. These data contribute to the cytotaxonomy of Scinax by providing chromosomal markers and demonstrating the occurrence of microstructural rearrangements and inversions on chromosomal evolution of Scinax.

Highlights

The genus Scinax (Anura: Hylidae) comprises 113 species widespread from southern Mexico to Argentina, Uruguay, Trinidad and Tobago and Santa Lucia islands (Frost, 2014)
Morphology, osteology, myology, reproductive biology and chromosomes, this genus was divided into two clades: S. catharinae and S. ruber (Faivovich, 2002; Faivovich et al, 2005)
In the clade S. catharinae, the first and second chromosomal pairs are submetacentric and NORs are usually located on the sixth pair, while, in the clade S. ruber, the first and second pairs are metacentric and NORs have been frequentle been detected on pair 11 (Cardozo et al, 2011)

Summary

Introduction

The genus Scinax (Anura: Hylidae) comprises 113 species widespread from southern Mexico to Argentina, Uruguay, Trinidad and Tobago and Santa Lucia islands (Frost, 2014). Karyotypes are known for only 39 species of Scinax and only few studies included banding methods, such as Ag-NOR staining, C-banding, BrdU, fluorochrome staining, and in situ hybridization (Pombal et al, 1995; Kasahara et al, 2003; Nunes and Fagundes, 2008; Cardozo et al, 2011). These cytogenetic studies showed that all species in this genus share a modal diploid value of 2n = 24. In the clade S. catharinae, the first and second chromosomal pairs are submetacentric and NORs are usually located on the sixth pair, while, in the clade S. ruber, the first and second pairs are metacentric and NORs have been frequentle been detected on pair 11 (Cardozo et al, 2011)

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Conclusion