 In the same paper in which they described "Lundomys", Voss and Carleton also, for the first time, diagnosed the tribe Oryzomyini in a phylogenetically valid way.Previously, Oryzomyini had been a somewhat loosely defined group defined among others by a long palate and the presence of a crest known as the mesoloph on the upper molars and mesolophid on the lower molars; this crest is absent or reduced in "Holochilus" and "Lundomys".Voss and Carleton recognized five synapomorphies for the group, all of which are shared by "Lundomys"; the placement in Oryzomyini of "Lundomys" and of three other genera—"Holochilus", "Pseudoryzomys", and "Zygodontomys"—which also lack complete mesoloph(id)s has been universally supported since.