A new staphylinoid beetle, Capnosolius ariasae gen. et sp. nov. is described from the Valdivian region of Chile. Members of this species display morphological affinities with both Leiodidae and Agyrtidae, including a weakly explanate pronotum, leiodid-like antennal club, and loss of aedeagal parameres. This new species is placed within its own genus on the basis of morphological uniqueness; the genus is tentatively placed within Camiarinae: Neopelatopini, with a discussion of support from morphological and DNA evidence. A key to described genera and a species checklist are provided for world Neopelatopini.