A taxonomic reassessment of the Centaurea busambarensis complex (Compositae, Cardueae), with description of a new species from the Egadi Islands (W Sicily)

The results of a statistical biometric study of the Centaurea busambarensis complex, which represents the C. cineraria aggregate in Sicily and its offshore islets, are presented. Seventeen populations, representing all seven previously recognized taxa (four species and three additional subspecies) plus a presumed undescribed one were studied. The statistical analysis (PCA and DA) of 26 morphological characters confirmed these eight taxa as distinct, geographically or ecologically vicarious units of equal weight, not supporting their treatment at different ranks. Consequently, they are recognized here as species, resulting in the description (with illustration) of one of them as new (C. aegusae, endemic to Favignana island, Egadi Archipelago, W Sicily) and in a new combination at species rank (C. seguenzae). A key for identifying the eight species of the complex is provided.