We describe a new species of Tomodon from ridge tops and xeric scrub forests in the southern Andes of Bolivia. The new species most closely resembles T. ocellatus and Pseudotomodon trigonatus. It has more maxillary teeth than either species and also differs in color pattern and meristic characters. The number of maxillary teeth (10–12) in the new species approaches the number in Thamnodynastes, thus blurring the distinction between Thamnodynastes and Tomodon and lending support to recent suggestions that these genera should be synonymized. The geographic and ecological distributions of the new species and Bothrops jonathani overlap, and these species appear to form a Müllerian mimicry system.