Siculosciadium, a new monotypic genus of Apiaceae from Sicily

The results of a morphological and molecular systematic investigation of the poorly known Sicilian endemic species Peucedanum nebrodense (Guss.) Nyman (Apiaceae subfam. Apioideae) are presented in order to better characterize the species and clarify its phylogenetic position. Morphological, karyological, anatomical, and ontogenetic studies indicate that this species is taxonomically distinct. Phylogenetic analysis of combined morphological and nuclear ribosomal DNA (nrDNA) ITS sequence data suggests an affinity with Dichoropetalum Fenzl, whereas an unweighted pair group method with arithmetic mean (UPGMA) analysis, based on 36 morphological characters, suggests that P. nebrodense is similar to Ormosolenia Tausch. Given its unusual life cycle; distinct suffruticose, evergreen, and dwarf habit; and peculiar fruit anatomy, we recognize P. nebrodense as distinct from Ormosolenia and Dichoropetalum, and we treat it as the new monotypic genus Siculosciadium C. Brullo, Brullo, S. R. Downie & Giusso based on S. nebrodense (Guss.) C. Brullo, Brullo, S. R. Downie & Giusso ≡ Pteroselinum nebrodense Guss., which is lectotypified herein.