Taxonomy and cytogeography of Cardamine raphanifolia and C. gallaecica (Brassicaceae) in the Iberian Peninsula

For a long time it was considered that Cardamine raphanifolia is widely distributed with several infraspecific taxa in the Mediterranean region. Recent studies showed that C. raphanifolia is restricted to the northern Iberian Peninsula. Cardamine gallaecica from NW Spain was regarded to be closely related, but was originally regarded as C. amara, and later described as C. raphanifolia subsp. gallaecica. In this study, we validate the treatment of C. raphanifolia and C. gallaecica as distinct species, and show their clear differentiation based on morphometric and molecular AFLP analyses. Moreover, both species are clearly distinct from C. amara subsp. pyrenaea, which has an overlapping distributional range with C. raphanifolia. Hexaploid (2n = 48) and octoploid cytotypes (2n = 64) of C. raphanifolia, and tetraploid (2n = 32) and hexaploid (2n = 48) cytotypes of C. gallaecica were found. Due to their weak morphological and genetic differentiation, these polyploid races are not classified as separate taxa.