The overharvesting of a plant can disturb population dynamics, threatening the species (Ticktin 2004, Rolland et al. 2011). This is especially true for narrowly restricted ones (IUCN 2017), such as the ‘candombá’, endemic to the Chapada Diamantina National Park (CDNP), northeastern Brazil. The extent of occurrence of the candombá is less than 200 km2 (Conceição et al. 2017), and the plant has been traditionally used to ignite fires in wood stoves (Ministério do Meio Ambiente 2007, Oliveira et al. 2013, 2015), with this use continuing today.

This work aimed to perform a comparative study of leaf anatomy, trichome frequency and essential oil production of some Lippia native species of the semi-arid region of Bahia, Brazil. Leaf samples were analyzed with light microscopy and scanning electron microscopy to describe the structure and to quantify the trichome frequency. Six types of glandular trichomes were identified: uni, bi and tetracellular, as well as three types of tectorial trichomes. L. bromleyana presents an ornamented epidermis and no tectorial trichomes on the abaxial surface. L. thymoides has glandular trichomes with irregular contours on both leaf faces, with a higher frequency of tectorial trichomes on the adaxial surface and peltate glandular trichomes on the abaxial surface. L. insignis and L. lasiocalycina are anatomically similar, and present a higher tector trichome frequency on the abaxial surface compared to the others species. L. thymoides and L. insignis are distinguished by the essential oil production.

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.