Karyotype description of two species of the genus Akodon (Rodentia, Sigmodontinae) in the northern Rio Grande do Sul state, Brazil

Caroline Badzinski,Daniel Galiano,Jorge Reppold Marinho,Bruno Busnello Kubiak,Cassiano Estevan

doi:10.5007/2175-7925.2015v28n3p187

Abstract

Among the sigmodontine rodents, the genus Akodon is the second in numerical terms, with about 45 recognized species. In the Rio Grande do Sul state, there are 5 registered species. This article shows data on the distribution of the species of the genus Akodon in the northern Rio Grande do Sul state, as well as a description of the karyotypes of species from this region are shown. Six localities were sampled from August 2008 to May 2010. A total of 44 specimens underwent cytogenetic analysis and 2 species were identified ( Akodon montensis and Akodon paranaensis ). The karyotype of A. montensis was 2n = 24, FN = 44 and that of A. paranaensis was 2n = 44, NF = 46. Data on abundance and distribution of these species corroborate the pattern described in other studies with the rodent community in the northern portion of the state, where the Akodon species are seen as dominant. The fact that only A. montensis and A. paranaensis were captured is an indication that these two species are the only ones with confirmed occurrence in the northern portion of this state.

Highlights

Among the South American rodent families, Cricetidae stands out, encompassing about 55% of the species described (MUSSER; CARLETON, 2005)
The data obtained in this study are in accordance with the already known distribution patterns of the genus Akodon described by D’Elía (2003) and Pardiñas et al (2003), where A. paranaensis and A. montensis might occur in sympatry
It has been identiied as one of the dominant species of rodent communities in other fragments of the northern Rio Grande do Sul state (GALIANO et al, 2007; 2013; KUBIAK et al, 2009). Both Akodon species are found in high altitude regions, especially A. montensis, found at an altitude above 700 meters in some regions along its distribution (GEISE et al, 2004; GONÇALVES et al, 2007; GALIANO et al, 2014). These two species belong to the cursor group (SMITH; PATTON, 2007), which shows an extensive karyotypic diversity, ranging from 2n = 14-15 in Akodon cursor Winge, 1887, to 2n = 44 in Akodon mystax Hershkovitz, 1998, Akodon paranaensis and Akodon reigi González, Langguth & Oliveira, 1998

Summary

Introduction

Among the South American rodent families, Cricetidae stands out, encompassing about 55% of the species described (MUSSER; CARLETON, 2005) This family is divided into 2 subfamilies: Sigmodontinae and Neotominae, and among the irst one, there is the tribe Akodontini, which has 12 genera and 63 species, accounting for 35% of the total diversity of the group. The genus Akodon includes species with high morphological similarity, showing a complex and poorly understood taxonomy (CHRISTOFF et al, 2000; HASS et al, 2008). For this reason, karyotypic analyzes are necessary in order to identify many Brazilian species (CHRISTOFF et al, 2000; GONÇALVES et al, 2007). Data on the distribution of the genus Akodon in the northern portion of Rio Grande do Sul state, as well as a description of the karyotypes of the species from this region were shown

Methods

Results

Conclusion