Rattus dammermani Thomas, 1921 is known from southwestern Celebes. Rattus toxi Sody, 1941 is a subjective synonym of that taxon. Although the name dammermani has been listed in the literature as a subspecies of R. rattus, it is actually a valid species that is morphologically more closely related to R. rattus than to any other species of Rattus known from Celebes.