Tackling the Paepalanthus elongatus complex (Eriocaulaceae) in central Brazil: nomenclatural changes and description of a new species from Goiás

In Paepalanthus ser. Dimeri, one of the few groups of Eriocaulaceae with dimerous flowers, the poorly understood circumscription of Paepalanthus elongatus and its numerous infraspecific taxa challenge the delimitation of the remaining taxa and distorts the group’s actual diversity. In order to clarify the taxonomy of the group in central Brazil, nomenclatural and taxonomic changes are proposed. Paepalanthus cassiae is described based on specimens usually misidentified as P. elongatus, as well as specimens collected on recent field trips. The new species is easily distinguished from P. elongatus by its smaller habit, dark castaneous leaf sheath, and golden to pale straw-colored involucral bracts, twice as long as the floral disc. Paepalanthus longibracteatus and P. niger are raised to species status based on P. elongatus varieties briefly described by Harold Moldenke. Detailed descriptions are provided for these species. The three species detailed occur in the vicinities of the recently extended Chapada dos Veadeiros National Park. Details of the species’ etymology, distribution, biology, conservation status, and morphological variation, along with illustrative photographs, are provided. Paepalanthus elongatus var. glabrescens is treated as a new synonym of P. elongatus var. elongatus.