The tail is bicolor, dark above and pale below, and clad in short, fairly dense fur, and the feet are brown on top with tufts of white hair between the digits, which have strong nails.

The exact boundaries are not well known, with various isolated outlying areas and with populations west of the Paraguay River overlapping the range of the Paraguayan bolo mouse (N. lenguarum).

[3] The hairy-tailed bolo mouse is mainly diurnal, with some activity at dusk and at night, particularly in the dry season.

Its diet varies with the time of year, but mainly consists of seeds and green plant material, and sometimes includes small invertebrates.

This mouse is a reservoir for certain hantaviruses, including the Araraquara strain from Brazil, which can cause disease in humans.