Molecular divergence in the genus Thrichomys (Rodentia, Echimyidae)

Molecular analysis of cytochrome b (about 1,100 base pairs) in Brazilian Thrichomys specimens from Pantanal, Caatinga, and Cerrado confirmed the monophyly of this genus in neighbor joining, maximum parsimony, and likelihood analyses. Molecular and karyotypic analyses suggested that T. pachyurus (2n = 34), T. inermis (2n = 26), and Thrichomys sp. nov. (2n = 30) belonged to different evolutionary lineages. The grouping of T. apereoides populations with different karyotypes (2n = 28, FN = 52 or 50; 2n = 30, FN = 54) was difficult to explain unless by postulating a recent karyotypic differentiation and/or random extinction of lineages of an ancestral population in which the mitochondrial DNA polymorphism was present.