Applying novel genetic tools to assist in the delimitation of species boundaries within the herbaceous bamboo lineage

Abstract The delimitation of species boundaries in taxonomically intricate plant groups can prove challenging due to inconsistencies in morphological and molecular data. In this study, we employed modern analyses to test the current species boundaries in the Neotropical herbaceous bamboo genus Raddia. This lineage shows high support in phylogenetic trees yet displays limited phylogenetic resolution at the innermost phylogenetic branches, thereby rendering the relationships between species and their boundaries ambiguous. To gain a deeper understanding of the evolutionary processes occurring in this lineage, we employed both a single-locus and a multi-locus approach utilizing population genetic data. The results from both approaches are largely concordant and consistent with the recognition of most of the currently accepted species as distinct lineages. However, some taxonomic species received lower support, suggesting either recent divergence or other processes that may obscure species boundaries. These findings highlight the challenges of species delimitation in recently diverged lineages in bamboos and indicate that additional data, particularly from genomic-scale markers and broader population sampling, may help to further clarify relationships specifically within Raddia. This study emphasizes the importance of continued research on plant groups with complex taxonomic histories and contributes to a better understanding of the processes underlying species diversification.