"I. tarsalis" is a docile, herbivorous animal that lives in trees. It is so distinct from other species that it was placed in its own genus, Irenomys, in 1919. The name comes from the Ancient Greek word εἰρήνη ("iren") meaning "peace", in reference to the end of World War I. Although it has been generally placed in the tribe Phyllotini, genetic evidence does not support any close relationships with other genera, so that it is now classified as a member of the subfamily Sigmodontinae "incertae sedis" (of uncertain position).