Astragalus austrobalcanicus, a new species of Astragalus sect. Caprini from southern Albania and northern Greece

Astragalus sect. Caprini includes 300 species occurring in dry habitats from lowlands to the alpine belt from northwestern Africa and western Europe in the West to Central Asia in the East. In Europe, approximately a dozen taxa occur and our recent phylogenomic study (Maylandt et al., 2025) revealed a genetically divergent lineage from the mountains of southern Albania and northern Greece that was traditionally treated as Astragalus exscapus, A. pubiflorus or A. exscapus subsp. pubiflorus. Here, based on an extended sampling for morphometric analysis we show that this lineage is morphologically distinct and differs from closely related, proximally occurring and/or morphologically similar A. exscapus, A. hellenicus, A. pubiflorus and A. transsilvanicus. Therefore, we here describe this lineage as a new species, Astragalus austrobalcanicus, and provide diagnosis, description, geographical distribution, and conservation status as well as a table with diagnostic characters differentiating it from its closest relatives. In addition, we established the chromosome number 2n = 16 for this new species.