The nothrotheriine sloth from riverbank deposits of the Río Acre region of Peru in western Amazonia was originally assigned to Nothropus priscus Burmeister, 1882. Although relatively complete, with essentially the pes unknown, its description was accompanied only by limited information on its cranial remains. The remains of this sloth, actually of late Miocene age, were extensively prepared. Subsequent analysis indicates that its original assignment is incorrect and that it belongs to a new genus and species, which is distinguished from other nothrotheriines by the following (among other) features: notably domed braincase; depressed, narrow snout; lack of parietal ⁄ alisphenoid contact; ulna with prominently projecting anconeal process; distal position of femoral greater trochanter; medial articular condyle of femur butts against patellar trochlea. Phylogenetic analysis places the new genus and species as sister group to the (Pronothrotherium (Nothrotheriops + Nothrotherium)) clade.