Studies of Vietnamese pteridophyte flora 4: topotype project

Nomenclatural types serve as reference points in biodiversity research, providing a stable foundation for species naming and identification. Despite their critical role in taxonomy, these specimens are often from old collections and are inaccessible for study using modern methodologies, such as molecular phylogenetics and reproductive biology. This gap can be bridged by recollecting new topotypic materials from type localities. In 2025, the "Vietnamese Pteridophyte Topotype Project" was launched using this approach to advance systematics studies. Here, the first results of this project are presented, including a detailed analysis of Vietnamese pteridophyte types, with emphasis on their historical background, taxonomic composition, and systematic significance. In addition, lectotypes are designated for Pteris quadriaurita var. parviloba Christ and Trichomanes javanicum var. glabra Bonap.