Tibouchina caatingae, a new species of Melastomataceae (Melastomeae), is herein described and illustrated. This species has been collected only in areas covered by caatinga vegetation in Bahia State, Brazil, and is one of the few species of the family registered for this type of vegetation. Due to the type of habit, organization of leaves on the branches, and color of the petals, it is morphologically similar to T. noblickii and T. lithophila. These are also endemic to Bahia, and are the only species from the genus that occur in the same vegetation type. However, these last two species have much smaller leaves, and glandular trichomes on the appendages of the stamens, while in T. caatingae the leaves are larger and the anthers have glabrous appendages on the stamens. Although these three species occur in the same type of vegetation, they were never found in sympatry. Based on IUCN criteria, T. caatingae can be considered endangered.