Introduction

Abstract

The woody genus Diplusodon Pohl is one of the ten genera of Lythraceae that is native to Brazil, and with 104 species, it is the second largest genus in the family.Diplusodon is characterized by a predominantly subshrubby or shrubby habit, showy 6-merous actinomorphic flowers, floral tubes on which the sepals alternate with conspicuous epicalyx segments, a style turned to one side of the corolla, and two whorls of stamens. The capsular fruit is divided by a bipartite placenta with lunate septa and contains winged seeds. The species occur mostly in the Cerrado Biome, the floristically diverse savannah that covers more than two million km2 of the Central Brazilian Plateau, extending west into Bolivia, south to Paraguay and east to the Caatinga Biome inhabit environments including grassy fields, cerrados of low elevation, and, less frequently, dense cerrados and margins of gallery and dry forests. However, the species are predominantly narrow-endemic to the campos rupestres and high-altitude rocky cerrados, where the largest diversity of Diplusodon species is found, occurring in small populations and often restricted to just one or a few adjoining mountains. A total of 103 species and eight varieties are recognized in the genus. New information on floral and vegetative morphology, pollen, cytology, chemistry, floral biology, habitat, and keys to the species accompanied by descriptions, illustrations, distribution maps, and assignment of conservation status. Diplusodon is a monophyletic genus and a molecular phylogenetic analysis using calibrated Bayesian analysis suggested that speciation was rapid and a mean date estimate of 3.46 Ma for the origin of Diplusodon. The chromosome number is constant for the genus indicating that speciation took place at the diploid level.