Malaxis ybytui is proposed as a new species from the wetlands of the Campos de Altitude of the Atlantic Rainforest of South Brazil. It is described, illustrated, and compared with other similar species. The new species is recognised by its flat to slightly conduplicate leaves, densely congested inflorescence with small flowers bearing free lateral sepals and four cavities in the lip. It is similar to Malaxis cipoensis and Malaxis sertulifera, being distinguished by its vegetative and floral morphology. The species is found in the mountain’s hillside about 1500m elevation in the Serra do Araçatuba\Papanduva mountain chain. Due to the high degree of endemism in this environment, the few collection records and the anthropic pressure in the region, we infer that the species is Critically Endangered (CR).