[1] An undetermined species of Rhagomys has also been reported from Mato Grosso in central Brazil.

[3] The species are as follows: This genus is distinguished from other sigmodontine rodents by the presence of a nail on the hallux.

[2] Nuclear DNA sequence analysis has indicated that it is a sister taxon to Thomasomys.

[4] While no other mammal taxa have a similar geographic distribution, a group of hylid frogs does.

[4] Some disjunct distributions have been attributed to fluctuations in forest coverage during the Pleistocene, resulting from the climatic swings of the ice age.