CONICET | Buscador de Institutos y Recursos Humanos

In this contribution, we publish chromosome data for 22 cheilanthoid ferns collected in Argentina. Counts of 12 species are reported for the first time, while the remaining 10 records corroborate previously published data. Our dataset confirmed the chromosome base numbers of 27, 29 and 30 for the cheilanthoid genera studied. Patterns of chromosomal evolution in Cheilanthoideae revealed that the plesiomorphic base number of x = 30 has been reduced independently in several lineages during the evolution of this group of ferns . Our data exhibited an array of different ploidy levels including 2x, 3x and 4x. All Adiantopsis, Argyrochosma and Doryopteris species examined, as well as four Cheilanthes species, were diploid, whereas polyploid counts were recovered for Astrolepis (3x), Gaga (3x), Myriopteris (3x), Pellaea (3x and 4x), and the remaining Cheilanthes studied (3x and 4x). Among the polyploids, six triploid apomictic species were detected. Polyploidy, hybridization and apomixis are frequent in cheilanthoid ferns, suggesting that they have played an important role in the diversification and evolution of this group