Consideraciones taxonómicas, citogenéticas y moleculares en Argyrochosma flava (Cheilanthoideae)

Abstract

The genus Aryrochosma (J. Sm.) Windham (Cheilanthoideae, Pteridaceae) was established by Windham in 1987. The genus is strictly Neotropical, is defined based on a unique combination of anatomical, cytological and palynological characters that circumscribe it as a natural taxon. These synapomorphies consist in sporangial distribution along the terminal portion of the veins; the spore morphology with a cristate-reticulate outer perispore, with a camerated inner stratum composed by tiny radial rodlet; in the chromosome number (x =27), the gametophyte morphology cordate with wide notch, symmetrical and glabrous, lacking farina producing trichomes; and the chemical composition of the farinose indument, and patterns of variability at conservative enzyme loci. Molecular phylogenetic analyzes within the subfamily confirmed that it is a monophyletic genus, close to the pellaeoid clade, with which share similarities in leaf architecture, sporangial disposition, and the spore structure, and distant from the notholaenoid clade that is characterized by presenting farinose indument in sporophytes and gametophytes. Argyrochosma flava appears to be a sexual diploid, n = 27, based on spore size and number of spores per sporangium. The yellow farina appears to be a synapomorphy of A. flava.