The Rio Negro tuco-tuco digs underground in sandy areas. Its large head and digging forefeet are distinctive features.
It has a short neck, a large head, small ears, and short forelimbs with large digging claws.
It digs burrows underground using its incisors and claws.
In Uruguay, some populations contain both black and agouti individuals.
It has uniformly black, agouti and dark-backed forms. The dark-backed form has a broad dark grey-brown stripe from the snout to the base of the tail.
An extinction-risk assessment has not been added yet.