The soles are naked and and have five well-developed tubercles. The claws also are well developed, but the nail of the thumb is small and appressed. The long and narrow hind feet have especially large claws. The body is stocky. The tail is shorter than the head and body, coarsely and conspicuously scaled, and uniformly brown.
Females have five pairs of mammae.
The skull is large and heavily built, the rostrum short and wide, the zygomatic plates very deep, the interorbital region narrow, the incisive foramina long and narrow, and the auditory bullae large and inflated. Based on molar occlusal pattern, Misonne considered Tryphomys to be closely related to Sundamys, but Musser and Newcomb disagreed. Also, in young adult Tryphomys the three laminae on each first lower molar consist of large, discrete cusps, whereas in Sundamys these laminae are noncuspidate.