Discovery of a new species of the genus <i>Astragalus</i> (Fabaceae) in the Zagros oak forests: insights from morphological and molecular data

Astragalus, the largest genus of flowering plants, exhibits a remarkable center of diversity within the Irano-Turanian floristic region. This study describes Astragalus dalahuensis, a new species from section Poterion, discovered in the Dalahu region of western Iran. While morphologically resembling A. bruguieri and A. russellii, A. dalahuensis is distinguished by its large calyx, stipules with a clearly visible midvein, and smaller fruits. Morphological analyses highlight these unique characteristics, and molecular phylogenetic analyses using ITS and matK sequences confirm its placement with other species grouped within section Poterion. These data, however, cast doubts on monophyly of this section, as our data make polyphyly of section Poterion likely. Endemic to the Zagros oak forests, A. dalahuensis faces significant threats from agricultural expansion and habitat degradation and should be categorized as Critically Endangered (CR) under IUCN criteria.