Ferns of the Parque Nacional das Nascentes do Rio Parnaíba, Brazilian Cerrado

Abstract The floristic and taxonomic treatment of ferns from the Parque Nacional das Nascentes do Rio Parnaíba (PNNRP), a protected area in the northern portion of the Brazilian Cerrado, within the boundaries of the states of Maranhão, Tocantins, Piauí and Bahia, is presented. Considered the largest full protection area of the Cerrado, the PNNRP is in a region rapidly losing its native coverage due to the expansion of agribusiness. This treatment includes identification keys for genera and species, descriptions, comments on diagnostic and ecological characteristics, species distribution, and illustrations. Twenty-five species were recorded in the study area, distributed in 11 families. Blechnum areolatum and B. asplenioides were recorded for the first time in the state of Maranhão, while Pteridium esculentum var. harpianum, Dicranopteris flexuosa, Trichomanes pilosum and Meniscium serratum are new records for the state of Piauí.