Abstract
Odontarrhenais a taxonomically difficult genus of the tribe Alysseae, including a number of critical species complexes in the Balkan Peninsula. One of these isO. baldaccii, which was previously included in the inconsistent taxonAlyssum fallacinumbut recently shown to be distinct from it.
In this paper, we analyzed the still uncertain taxonomic circumscription ofO. baldacciiby a comparative analysis of the population from the type locality in Crete and other populations from mainland Greece, which were previously attributed toA. fallacinumor dubitatively included inO. baldacciis.l. The results supported the separation of these mainland populations in a new distinct species, here described asOdontarrhena stridii, sp. nov.
Plant habit, leaf shape and size and silicle shape were the major distinguishing morphological characters. Molecular data also suggested divergence between the two groups of populations, while supporting their phylogenetic affinity.
The two species are diploid schizo-endemics with 2n = 16, allopatric distribution and specialization for serpentine soils. Shoot Ni concentrations well above 1000 mu g g(-1)dry weight were confirmed for the Cretan population ofO. baldacciiand found for the first time in two populations ofO. stridii, which is therefore a new hyperaccumulating species of the Balkan Mediterranean flora.
An updated key to the GreekOdontarrhenataxa is provided.