Systematics, phylogenetic relationships and conservation of the taxa of Anchusa (Boraginaceae) endemic to Sardinia (Italy)

Sardinia is a major centre of diversity of Anchusa, but the systematics, phylogenetic relationships and conservation status of the taxa endemic to the island are still poorly known mainly because of their remarkable rarity. We present a study on these endemics based on the results of field research focusing on the distribution, the number and size of the populations, the characteristics of the habitat and the factors of threat. Combined with observations on aspects of reproductive biology, on wild populations and cultivated plants, we evaluate the conservation status of the taxa and propose Red List IUCN categories of vulnerability. Original descriptions, nomenclatural types and karyological data are added. The following Anchusa taxa are endemic to Sardinia: A. capellii, A. crispa ssp. crispa, A. crispa ssp. maritima, A. formosa, A. littorea, A. sardoa and A. montelinasana sp. nov. The latter is described, based on the discovery of a morphologically distinct entity on a mountain in southwest Sardinia. Anchusa littorea was found at a single site after C. 25 years from the last record and 7 years of unsuccessful field research; this species is at the brink of extinction due to the extremely reduced size of the only remaining population. Our complete collection of taxa allowed an analysis of phylogenetic relationships based on DNA sequences from the ITS1 ribosomal genome. In spite of the low variation, this marker produced Maximum Parsimony and Neighbour-Joining phylograms suggesting that the group is monophyletic and that the split between the two clades of the mountain and coastal endemics has been a key evolutionary event. We assume the three mountain species to be relict schizoendemics ancestral to the coastal taxa, and the Paleozoic siliceous massifs of central and south Sardinia as the centre of origin of the group.