We describe two new species of Calibrachoa (Solanaceae) from southern Brazil grasslands. The new species were first detected by molecular data, and later corroborated by morphological traits and field observations. Both species are erect shrubs with showy purple corollas. The main distinctive morphological traits are the marked dark purple ring contrasting with the yellow corolla throat and the lobed stigma in C. atropurpurea, and the long androecium reaching the distal part of the corolla tube and the connivent anthers in C. synanthera. A key for the species with purple flowers from the Rio Grande do Sul Brazilian State, where the species were found, is given.