Leandra hermogenesii (section Oxymeris), a new endemic species of Melastomataceae from São Paulo, Brazil, is described and illustrated. The distinguishing characteristics of the species include its leaves, which are subcartaceous, ovate to broadly ovate, 5(–7)-plinerved, 5.6–9.6 cm wide, and have a rounded base, its smaller bracts, bracteoles, and glabrous petals , and its larger ovary. A discussion and an identification key to morphologically related species are also presented.