RESUMO: The study of the original description and the holotype – and only known specimen – in the Natural History Museum, London, allows us to transfer the Brazilian Amazon species Choeridium tridenticeps Arrow, 1913, currently treated in Ateuchus Weber, 1801 (= Choeridium Le Peletier de Saint-Fargeau & Audinet-Serville, 1828), to the genus Canthidium Erichson, 1847. Features such as a trituberculate head, protibiae serrated along the outer edge, and a row of deep punctures covering the posterior edge of the pronotum are alien to Ateuchus, but commonly found in Canthidium. At the same time, the specimen matches all known diagnostic features of Canthidium, with the posterior pronotal punctation placing it in the subgenus Neocanthidium Martínez et al., 1964. The new combination Canthidium (Neocanthidium) tridenticeps (Arrow, 1913) is thus established. Canthidium now includes 176 species. The C. tridenticeps holotype was collected during the Amazon leg of the 1911 Stanford Expedition to Brazil, along the Madeira-Mamoré Railroad, then under construction. We provide coordinates for each of the construction camps visited by the collectors W.M. Mann and F. Baker, including Camp 28 (09°38′57″S, 64°58′05″W), in modern Mutum-Paraná (Porto Velho, Rondônia), the type locality of C. tridenticeps. This is a preliminary contribution from our ongoing Ateuchus and Canthidium revisionary projects.
doi: https://doi.org/10.11606/1807-0205/2026.66.special-issue-1.012