Cardamine apennina: a new endemic diploid species of the C. pratensis group (Brassicaceae) from Italy

Italian representatives of the Cardamine pratensis group were investigated using morphometric, karyological, and molecular (AFLP-fingerprinting) analyses. Focus was on resolving the taxonomic and evolutionary position of C. granulosa from Piemonte (NW Italy) and of populations from central Italy, previously included in C. granulosa or C. pratensis s. str. Results show that C. granulosa is a morphologically and genetically well defined diploid species, but is extremely rare and restricted to a small area in Piemonte. Central Italian populations differ from both C. granulosa and C. pratensis s. str., and, although the morphological differentiation is not strongly pronounced, they show marked molecular divergence, suggesting recognition as a new species, Cardamine apennina. Because of their restricted distribution and diploid chromosomal level, C. apennina and C. granulosa may represent basal and quite isolated lineages, whereas reticulation on diploid and polyploid level has affected remaining lineages of the C. pratensis group. Both Italian endemics are endangered due to rarity and habitat loss. A key for identification of the Italian taxa of the C. pratensis group is also provided.