Allium erimomeli, a new hexaploid species of A. sect. Codonoprasum (Amaryllidaceae) from Milos and Antimilos Islands (Kiklades, Greece)
TL;DR
The recognition of Allium erimomeli as a distinct species emphasizes the significance of polyploidy and insular isolation in the diversification of A. Codonoprasum in the Aegean region and enhances the understanding of evolutionary relationships within the section.
Abstract
Background and aims – The genus Allium exhibits extensive diversification in the Mediterranean Basin, where insular endemism and polyploidy have played a significant role in species evolution. During taxonomic and biosystematic studies of A. sect. Codonoprasum , an undescribed species was discovered on the volcanic islands of Milos and Antimilos (Kiklades, Greece). This study aims to determine its taxonomic status and phylogenetic relationships using an integrative approach. Material and methods – The new species was investigated using comparative morphology, leaf anatomy, karyological analyses, genome size estimation by flow cytometry, and phylogenetic reconstruction based on nrITS sequence data. These data were compared with those of closely related species, particularly A. occultum , as well as other representatives of A. sect. Codonoprasum from Europe and the Mediterranean region. Key results – Allium erimomeli is described here as a new species. Karyological and flow cytometric analyses revealed a hexaploid chromosome complement (2 n = 6 x = 48) with a mean genome size of 46.2 pg. Phylogenetic reconstruction recovered the species as a strongly supported clade sister to the tetraploid A. occultum . Despite their close phylogenetic relationship, the two taxa differ in ploidy level, genome size, and diagnostic morphological characters, primarily relating to the bulb, leaves, and ovary. Additional differentiation is supported by leaf anatomy. Morphological characters were also compared with those of A. sibthorpianum and A. rumelicum . Conclusion – The recognition of A. erimomeli as a distinct species emphasizes the significance of polyploidy and insular isolation in the diversification of A. sect. Codonoprasum in the Aegean region. These findings further enhance our understanding of evolutionary relationships within the section and call for expanded phylogenetic and cytogenetic sampling across the eastern Mediterranean region.