Jamesonia (Pteridaceae) in Brazil

Abstract

Jamesonia is a genus of Neotropical ferns that comprises about 50 species, distributed from Mexico to Uruguay. In spite of this wide distribution, this group is more diverse in Andean páramos and subpáramos. Due to the recent changes in its circumscription, with the junction of Eriosorus and segregation of Tryonia, the objective of this work was to carry out the taxonomic study of Jamesonia for Brazil, in order to elaborate its monograph to the Flora of Brazil 2020. This study was based on morphological analyses of specimens deposited in 25 Brazilian herbaria, plus online images of types, field expeditions in the southern and southeastern regions of Brazil, revision of the literature, and scanning electronic microscopy of the spores. Seven species and two hybrids were recognized: J. biardii, J. brasiliensis, J. cheilanthoides, J. flexuosa, J. insignis, J. osteniana, J. rufescens, J. brasiliensis × J. cheilanthoides, and J. ×intermedia, respectively. A distinct specimen, from the border of Brazil (Amazonas) and Venezuela, was treated as Jamesonia sp., due to the presence of only one material. Identification key, descriptions and illustrations are provided for the species and hybrids, as well as, geographical distribution data, comments, list of selected material examined for each taxon, and a full list of all exsiccatae analyzed. We also present an identification key for the genera Jamesonia and Tryonia.