Abstract
Dichanthelium is a genus belonging to the family Poaceae, included in the subfamily Panicoideae. It is widely distributed on the American continent, from Canada to Argentina. In Brazil, several species are endemic, mainly to the Chapada Diamantina, the Bahian portion of the Espinhaço range. One of them, D. cumbucana, has a problematic circumscription. During the preparation of a taxonomic account of Dichanthelium for Bahia, we found some specimens from Morro do Chapéu, a municipality of the northern portion of Chapada Diamantina, to be similar to D. cumbucana, but with distinguishing features. After morphological, anatomical and scanning electron microscopy (SEM) analyses, we found significant differences in the vegetative and reproductive characters of these specimens. Based on these data, we consider these specimens to be part of an independent taxon, herein described as the new species D. arenicola, which is only known from areas of sandy soils associated with “campo rupestre” vegetation. We also provide illustrations, data on habitat and distribution, as well as a conservation status assessment for the new species.