 Its external morphology is similar to that of "Holochilus brasiliensis", and over the course of its complex taxonomic history it has been confused with that species, but other features support its placement in a distinct genus, Lundomys.Within the family Cricetidae and subfamily Sigmodontinae, it is a member of a group of specialized oryzomyine rodents that also includes "Holochilus", "Noronhomys", "Carletonomys", and "Pseudoryzomys".