Two new Brazilian species of Tachia (Gentianaceae: Helieae)

Two new species of Tachia (Gentianaceae: Helieae) are described from Brazil. They share the unusual characteristic of quadrangular, winged stems, formerly only known from Tachia longipes in Suriname. They differ from this species in their larger, winged, keeled, and long-acuminate calyx lobes. Tachia lancisepala, spec. nov., is only known from one collection from the State of Rondônia in Brazil, and has unusually large and broadly funnelshaped corollas and ovate leaves with winged petioles. Tachia siwertii, spec. nov., has been found in three separate areas in southern Amazonas and Pará (Brazil) and is characterized by more elliptic leaves, unwinged petioles, and a narrower corolla than T. lancisepala.