Yonenaga's spiny-rat is known from dunes along the middle São Francisco River in northwestern Bahia, Brazil. It digs its own burrows, and field data indicate that adults sometimes share burrow systems.
Its coat is paler than that of other Trinomys: pale cinnamon on the back, mixed with darker hairs, fading on the sides and contrasting with the white underside. It has long hind feet and a long, two-colored tail with a conspicuous hair tuft.
It digs burrow systems in valleys among the dunes. Field observations found adults sharing burrows and sometimes nest sites; the account also reports Eugenia seeds as a major source of food and water.
An extinction-risk assessment has not been added yet.