Stachytarpheta lajedicola (Verbenaceae), a new species from the Caatinga of Minas Gerais state, Brazil: the first report of the genus in limestone outcrops

Stachytarpheta is one of the largest genera of Verbenaceae, found mainly in the campos rupestres of Brazil. We describe a new species, Stachytarpheta lajedicola, and report for the first time the occurrence of the genus in limestone outcrops. The new species is endemic to the Caatinga domain, northern Minas Gerais state, growing in an open karst formation of the municipality of Matias Cardoso, locally known as Lajedão. Its main diagnostic characteristics are the branches with well-developed longitudinal edges, leaves with attenuate to caudate apex, and inflorescences with linear bracts, exceeding the calyx in length. We provide a detailed description, illustrations, photographs, a geographic occurrence map, and comparisons with the morphologically similar species. Stachytarpheta lajedicola may be considered Critically Endangered (CR), and the biological importance of Lajedão and the conservation of the new species are discussed.