The mordax rat is a medium-sized rat of mainland eastern New Guinea. It has been recorded in forests, gardens, and cultivated areas.
Its back is rust-brown with yellowish-brown hair tips. The fur is coarse and spiny, and the underside is dull cream. The tail is one-colored and shorter than head-and-body length.
It is terrestrial and digs burrow systems. The guide reports it more often in gardens, plantations, and human-altered grassland than in primary forest. It sometimes enters village houses for stored rice or sweet potato but is not described as a true village resident.
An extinction-risk assessment has not been added yet.