Morphological and phylogenetic analysis approach to three new species and a new section of Astragalus (Fabaceae) from Mongolia

<i>Astragalus</i> L. is the largest genus worldwide, comprising more than 3,100 species belonging to 250 sections. In Mongolia, approximately 130 species, including 15 endemic and 25 subendemic species have been previously recognized from 42 sections and 6 subgenera. In this study, we investigated several species within section Laguropsis in Mongolia based on extensive morphological analyses and molecular evidence. Based on these results, we describe three new species and a new section. Two of the newly described species, <i>A.oyunicus</i> and <i>A.teshigicus</i>, belong to the section Laguropsis, whereas the remaining species, <i>A.uvsicus</i>, is the type species of the new section Uvsicus. Furthermore, our findings revealed that (i) <i>A.tamiricus</i>, previously considered endemic to Mongolia, is an additional synonym of <i>A.laguroides</i>, and (ii) <i>A.gobi-altaicus</i>, previously a synonym of <i>A.laguroides</i>, is an independent species. Finally, we provide taxonomic nomenclature, morphological observations, distribution maps and wild photo illustrations of each species.