Out of the Balkans and Anatolia to the Western Alps? Surprising phylogenetic implications for two endemic <i>Alyssum</i> (Brassicaceae) species: <i>A. cognense</i> sp. nov. and <i>A. rossetii</i>

Abstract The European Alps show a high degree of endemism associated mainly with the location glacial refugia and environmental heterogeneity. Several Alpine endemics have evolved in genus Alyssum. Here we study perennial Alyssum populations Western Alps, distributed Aosta Valley region, which hosts species diversity, although are rare. We addressed recently described stenoendemic A. rossetii taxonomically uncertain usually attributed to montanum s.s. clarify their phylogenetic position morphological differentiation. latter entity has been shown be distinct from is as new species, cognense, phylogenetically placed montanum–A. repens complex. Both genetic patterns revealed that its closest relative occurs central Balkans. present detailed ecological characteristics differentiation cognense sp. nov. relatives geographically speculate on biogeographic origin. Genetic (reduced diversity nestedness) suggest long-distance dispersal Balkan Peninsula. second studied rossetii, distant belongs Asian section Gamosepalum lineage, includes few representatives southern eastern Europe. Anatolian endemics, so this extreme disjunction remains puzzling. illustrates need for in-depth taxonomic studies, even well-explored regions, also shows processes underlying evolution can complex poorly understood.