Revision of Adiantopsis radiata (Pteridaceae) with Descriptions of New Taxa with Palmately Compound Laminae

Adiantopsis radiata has long been regarded as the only species with palmately compound laminae in the fern genus Adiantopsis (Pteridaceae). Here, three new species, A. dactylifera, A. timida, and A. crinoidea, with palmate laminar architecture are described. Additionally, a new combination is formalized for A. trifurcata, a typically ternate species originally assigned to Cheilanthes and frequently misidentified in herbarium collections as A. monticola, which is a pinnately compound species endemic to the states of Goias and Tocantins, Brazil. Adiantopsis ternata is affirmed as a distinct and valid species that should not be placed in synonymy with A. rod into. These six palmately compound species differ from each other in the form of their pseudoindusia, the position of attachment of the pinnules to the costae, the form of the adaxial carinae, the shape of the pinnae apices, as well as spore size and ornamentation. All six Adiantopsis species with palmately compound laminae are illustrated, and a distribution map and key are provided.