Abstract
Twelve new species of Bibrax Fletcher, 1927 (Coleoptera: Staphylinidae: Pselaphinae: Euplectitae: Metopiasini) from Ecuador are described: B. chullachaqui sp. nov., B. chocoensis sp. nov., B. onorei sp. nov., B. aratrifer sp. nov., B. longiventer sp. nov., B. cerroblanco sp. nov., B. canelazo sp. nov., B. pectinifer sp. nov., B. arachnoides sp. nov., B. amasanga sp. nov., B. yasuni sp. nov., and B. grandis sp. nov. A key for all species of Bibrax is provided. These are the first records of the genus for the country, and we report species from most major environments in the country, from seasonal coastal forests to cloud forests and the Amazonian Basin. The new species expand the scope of morphological variability in the genus, with discovery of numerous microphthalmous and wingless species, and a range of previously unreported secondary sexual characters. Most of the species are only known from single localities, suggesting a large fauna remaining to be discovered from a large portion of South America.