First micromorphological characterization of pollen in the newly described species <i>Hesperis sivasica</i> (Brassicaceae) using integrated light and scanning electron microscopy

This study presents the first detailed palynological characterization of Hesperis sivasica, a recently described species from Türkiye. To place the new species within its taxonomic context, pollen features were also analyzed for three closely related taxa: H. bottae, H. kotschyi, and H. thyrsoidea. These comparative species were selected based on morphological similarities and phylogenetic proximity indicated by previous ITS sequence analyses, with H. kotschyi representing the morphologically closest species and H. thyrsoidea and H. bottae representing its closest phylogenetic relatives.Both qualitative () and quantitative () pollen characters were examined using light microscopy (LM) and scanning electron microscopy (SEM). Multivariate cluster analysis was performed to assess the taxonomic closeness of H. sivasica relative to the other species.The results indicate that while all taxa share common Brassicaceae pollen features; tricolpate apertures and reticulate ornamentation, subtle differences in pollen shape, lumen size, and exine microstructure allow differentiation among them. H. sivasica is most closely related to H. kotschyi, followed by H. bottae and H. thyrsoidea shows the greatest divergence, reflecting both morphological and phylogenetic patterns. This study underscores the importance of integrated LM and SEM palynological analyses in resolving fine-scale taxonomic relationships and supporting systematic placement of new species.