[1] Members of the tribe Oryzomyini ("rice rats"), in the Cricetidae subfamily Sigmodontinae, normally have ungual tufts, but they may be reduced or absent in semiaquatic species (i.e. those adapted to life in the water).
[2] Lundomys molitor, Nectomys apicalis, the marsh rice rat (Oryzomys palustris), and species of Holochilus lack ungual tufts on their forefeet.
Pseudoryzomys simplex, Mindomys hammondi, Nectomys squamipes, Sigmodontomys alfari, Oryzomys couesi, the marsh rice rat, and species of Melanomys have sparse ungual tufts only, and Lundomys molitor, Nectomys apicalis, Sigmodontomys aphrastus, and species of Holochilus have very reduced tufts or lack them entirely.
[4] Among other South American cricetids, Abrothrix lanosus has white ungual tufts that are shorter than the claws.
[11] The Brazilian spiny rat Phyllomys sulinus has long, light gray ungual tufts.