Estudos citogenéticos e moleculares nos gêneros Mesomys e Lonchothrix (Rodentia, Echimyidae, Eumysopinae)

Abstract

The Echimyidae family is considered the most taxonomically diverse among South American hystricognathi rodents, comprising 25 genera and 93 species. The subfamily Eumysopinae is represented by nine genera, among which we highlight the arboreal genera Mesomys, which has four recognized species, and Lonchothrix described as monotypic (L. emiliae), both distributed in the Amazon. Morphological, molecular and chromosomal studies in the genera Mesomys and Lonchothrix have contributed to a better understanding of taxonomic design, phylogenetic relationships and karyotypic patterns. Recent molecular investigations have shown an as yet undescribed diversity, suggesting that these taxa are even more diverse than previously assumed. Furthermore, the limits of geographic distribution in the Amazon for the species M. hispidus and M. stimulax have been questioned by some authors. In this sense, the current study sought to investigate the karyotypic diversity and the geographic limits of the Mesomys and Lonchothrix genera, based on classical and molecular cytogenetic analysis and through sequences of the mitochondrial genes Cytochrome b (Cytb) and Cytochrome Oxidase - Subunit I (COI) from different locations in the Brazilian Amazon. The species M. stimulax and Mesomys sp. n. presented 2n=60/NF=110, while M. hispidus presented 2n=60/NF=112 and Lonchothrix emiliae presented 2n=66/NF=126, both unpublished karyotypes for the genera. Phylogenetic analysis confirmed Mesomys and Lonchothrix as sister genera and showed a high intraspecific rate in M. hispidus and Mesomys sp. n. from Itaituba, may be related to a new lineage in the genus Mesomys.