Boyania colombiana Humberto Mend. (Melastomataceae) is described and illustrated from an area of sandy soils in the department of Caquetá, Colombia. It is a disjunct species in a monotypic genus known from the Guayana Shield in Guyana. Boyania colombiana is distinguished from B. ayangannae Wurdack by the shape of the leaf base, the petiole longer than 2 cm, the shortened internodes, and the absence of a dorsal connective appendix. Boyania colombiana is compared to other genera of the tribe Bertolonieae, and the generic position of the new species is discussed.