The monotypic genus Argelodes Ruta, which includes the species A. magnificus Ruta (Coleoptera, Scirtidae), was originally described based on a single male from Argentina. Prior to this study, this male represented the only known individual of the species. Here, we report the genus Argelodes from Chile for the first time and provide the first formal description of the female, along with habitus and genitalia illustrations. The female of A. magnificus is similar to the male in body coloration and general shape, but exhibits sexual dimorphism, with less protuberant eyes, a more convex pronotum, and a more robust body. This study also includes a comparison with other large-sized Scirtidae genera occurring in Chile.