Studies of Vietnamese Pteridophyte Flora 3.

This is the third paper in a series dedicated to updating the knowledge of the Vietnamese pteridophyte flora. Based on recent collections, we first reported three new national records of ferns: Haplopterisyakushimensis, Lindsaeakohkongensis, and Pterispseudowulaiensis. Secondly, we conducted phylogenetic analyses to investigate the placements of Lindsaeakohkongensis and Leptochiluspoilanei, each based on three plastid DNA markers. Our results revealed that Lindsaeakohkongensis is sister to L.ensifolia, while Leptochiluspoilanei is embedded within L.cantoniensis. We discussed these results in the context of systematics. Lastly, we reported chromosome numbers for 20 fern species in Vietnam. For seven of these species, including Gymnosphaerasalletii, Lepisorusspicatus, Leptochiluspoilanei, Pteridryscostularis, Pterislatipinna, Pyrrosiaeberhardtii, and Tectariasetulosa, these counts were recorded for the first time. Additionally, three new cytotypes were identified for Diplaziumdoederleinii, Pterisesquirolii, and Tectariaharlandii. This study underscores the need for more diverse data, including DNA sequences, chromosome numbers, and reproductive modes, to be collected and integrated into systematic studies and taxonomic treatments to enhance our understanding of Vietnam's pteridophyte flora.