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).

我们描述了Pterolepis xaxa（野牡丹科，野牡丹科），这是一种在巴西巴伊亚州 Licínio de Almeida 的“caatinga rupestre”采集的新物种。Pterolepis xaxa与最近描述的Pterolepis haplostemona相似，两者均代表该属中仅有的两个单茎植物（即，雄蕊的数量与花瓣的数量相等）。除了具有单轮雄蕊的花朵外，P. xaxa还可以通过由非常短的中心轴组成的间质突起和白色花瓣（相对于在顶端和洋红色或洋红色或P. haplostemona中的丁香花瓣）。