Long-term fieldwork in Brazil helps to unravel the diversity and evolution of the Neotropical Olyreae (Poaceae: Bambusoideae): an unexpected new and threatened genus in Parianinae

Abstract Fieldwork has historically increased knowledge about plant biodiversity in Brazil, including the herbaceous bamboos (grass tribe Olyreae), which is almost exclusive to the Neotropical region. Several new species and three new genera from both Atlantic and Amazonian forests were described from this tribe in the past 15 years. Our recent collections in the central region of Espírito Santo state revealed two distinct populations of a sterile but probably undescribed species similar to members of Eremitis in the subtribe Parianinae (Poaceae: Bambusoideae: Olyreae). Only after recollection did we find plants with synflorescences, which turned out to be very similar to members of Parianella. We investigated the macro- and micromorphology of those specimens and estimated the phylogenetic placement of type collection based on two plastid markers, which recovered it as an independent lineage sister to the Pariana + Eremitis clade. We herein describe this entity as the new genus Aemulanthus and the new species Aemulanthus decumbens, distinguishable mainly by the presence of spiciform synflorescences on decumbent culms composed of monomorphic gynaecandrous whorls, with long laminar pedicels in the male spikelets, also using information given by scanning electron microscopy (SEM) of the leaf blades. Aemulanthus is endemic to central Espírito Santo state, Brazil, and is considered Critically Endangered (CR) following IUCN guidelines. The description of this new genus increases our understanding of the diversity and evolution within this group. It also reinforces the need to preserve local floras, which can be important resources for knowledge about and conservation of Neotropical forests.