 According to phylogenetic analysis of sequences from the mitochondrial cytochrome b gene , Akodon spegazzinii is most closely related to A. boliviensis and more distantly to other members of the A. boliviensis species group , including Akodon polopi and Akodon sylvanus . The boliviensis group is part of the highly diverse genus Akodon and thereby of the tribe Akodontini , which includes about 90 species of South American rodents . Akodontini is one of several tribes within the subfamily Sigmodontinae and the family Cricetidae , which includes hundreds of mainly small rodents distributed chiefly in Eurasia and the Americas . 
