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Digital archive of theses discussed at the University of Pisa


Thesis etd-11222022-112000

Thesis type
Tesi di dottorato di ricerca
Thesis title
Biosystematics and integrative taxonomy of the Santolina chamaecyparissus complex (Asteraceae)
Academic discipline
Course of study
tutor Prof. Peruzzi, Lorenzo
  • Anthemideae
  • endemism
  • karyology
  • Mediterranean Basin
  • molecular systematics
  • morphometry
  • niche analysis
  • nomenclature
Graduation session start date
The Santolina chamaecyparissus complex (Asteraceae, Anthemideae) includes 14 species of aromatic shrubs and subshrubs endemic to the western Mediterranean region. Most species are important for ornamental purposes, in ethnobotany and for phytochemical studies. However, the taxonomy of this complex was unstable in the past, mostly because the circumscription of species was still based just on qualitative morphological observations. A three years phD research project was carried out to push forward the knowledge concerning the taxonomy and systematics of the S. chamaecyparissus species complex. As first, all names within the complex, both accepted and synonyms, were typified in order to fix the application of the names. Then, all species were sampled for a total amount of 27 populations, including type localities and populations with an uncertain taxonomic position. An integrative taxonomic approach was carried out involving morphometrics, cypsela morpho-colorimetrics, karyological analysis, molecular systematics, and niche analysis. A karyological study pointed out the presence of four ploidy levels in the complex (diploid, tetraploid, pentaploid, and hexaploid). Then, an integrated taxonomic study was conducted on the two polyploid putative species endemic to Corsica and Sardinia, i.e. S. corsica and S. insularis. The results suggested that, despite the different ploidy level, these species cannot be separated and should be considered as a single polymorphic species, namely S. corsica. A similar approach was carried out on populations from southern-France and north-eastern Spain, where several taxonomic issues were pointed out by the nomenclatural works. Indeed, the presence of new endemic taxa was revealed. Finally, a morphometric study including all the newly circumscribed species was conducted to have a complete picture of the morphological variation of the complex and to build an identification key for all taxa. The results of the research project pointed out the importance of integrative taxonomic studies to correctly interpret the variation of Mediterranean plant species. A reliable taxonomic setting is crucial to measure biodiversity, and it is fundamental also for ecological studies and conservation practices.