ETD

• Centaurea
• endemism
• functional traits
• karyology
• morphometry
• systematics

The genus Centaurea L. (Asteraceae) is one of the most diverse and taxonomically complex plant genera within the Mediterranean region. A representative case is C. aplolepa Moretti, an Italian endemic plant occurring in Tuscany, Liguria, Emilia-Romagna, and Piedmont. In Tuscany, three subspecies are actually recognized: C. aplolepa subsp. carueliana (Micheletti) Dostál, C. aplolepa subsp. cosana (Fiori) Dostál, and C. aplolepa subsp. subciliata (DC.) Arcang. In addition, “C. aplolepa subsp. maremmana” sensu Arrigoni was also included in the present work, although it is currently treated as a heterotypic synonym of C. aplolepa subsp. carueliana. To evaluate their taxonomic value, an integrative taxonomic approach was applied, combining morphometrics, functional traits, and karyological analyses. Fifteen morphological characters (related to the general morphology and the structure of floral heads, leaves, and cypselae), three functional traits (LDMC, cypselae biomass, plant height), and karyotype asymmetry indices (MCA, CVCL) were analysed. Statistical analyses revealed that C. aplolepa subsp. subciliata is morphologically distinct. LDMC values are largely uniform, but cypselae biomass and plant height further differentiate this taxon. Karyological analyses confirmed the diploidy level (2n = 18), with C. aplolepa subsp. subciliata showing a slightly higher karyotype asymmetry values. This study highlights the need to reevaluate the current taxonomic circumscription of C. aplolepa in Tuscany, since, based on several evidence, C. aplolepa subsp. subciliata is the only clearly distinct taxon.