Pterolepis xaxa (Melastomateae, Melastomataceae), a new haplostemonous species from Bahia, Brazil

We describe Pterolepis xaxa (Melastomateae, Melastomataceae), a new species collected in “caatinga rupestre” at Licínio de Almeida, Bahia, Brazil. Pterolepis xaxa resembles the recently described Pterolepis haplostemona, both representing the only two species in the genus that are haplostemonous (i.e., with the stamens equal in number to the petals). Apart from flowers with a single whorl of stamens, P. xaxa can also be recognized by intercalycine projections consisting of a very short central axis topped with 2–3 trichomes, and white petals (vs. intercalycine projections lacking trichomes at the apex and magenta or lilac petals in P. haplostemona).