Background – Studies of neotropical Monimiaceae revealed a new species of Mollinedia endemic to the state of Espírito Santo, eastern Brazil. In this study, we describe, illustrate, and compare the new species with related taxa. In addition, ecological comments and extinction risk assessment of the new species are provided.Methods – This study was based on herbarium material and field work observations. The risk of extinction assessment follows the IUCN Red List of Threatened Species’ Criteria and Categories and the latest version of the IUCN Guidelines.Results – Mollinedia ruschii sp. nov. has habitat specificity with few individuals recorded, mainly in the Estação Biológica de Santa Lúcia, a protected area created by Augusto Ruschi, a Brazilian naturalist and researcher, to whom we dedicate the name of the new species. Phytosociological and forest dynamics studies and intensive field work in the area where the species occurs, enabled the detection of the decline of mature individuals in previous decades. Following the IUCN Red List criteria, the species is assessed as Critically Endangered.