Lycophytes and ferns of an Amazonian-Cerrado ecotone in Maranhão State, Northeastern Brazil: identification key and annotated list of taxa.

Abstract

We present a key to identify and an annotated list of lycophytes and ferns of the Immediate Geographical Region of São Luís, Maranhão State, which has ecotonal characteristics of Amazonian Forest, Cerrado, and Coastal Vegetation. Specimens were collected monthly between April 2020 and September 2022 in the 13 municipalities of this region. A total of 64 species were identified, including 61 species of ferns, in 18 families and 38 genera, and three species of lycophytes, in two genera and one family. The most representative families were Pteridaceae (18 species) and Polypodiaceae (nine species). The most recorded substrate of occurrence was terrestrial with 35 species (54.6%), followed by epiphytic with 15 species (23.4%), aquatic with four species (6.2%), rupicolous with three species (4.6%), and hemiepiphytic with two species (3.1%). Five species (7.8%) had more than one life form. This study expands the knowledge about the geographic distribution of fern and lycophyte species in the central region of Northern Maranhão, in Northeastern Brazil, which until now had several sampling gaps. Maranhão has a diversity that is still poorly reported and known compared to other states in South and Southeast Brazil. Therefore, floristic surveys are essential to increase what is known about the flora, especially in areas under anthropic pressure and places with few collections, such as the ecotonal areas in Maranhão.