Biodiversity in some populations of Crataegus (Rosaceae) from western Sicily: Description of two new species and notes on conservation and valorisation

The genus Crataegus, distributed across the temperate regions of almost all continents, constitutes an extremely variable taxon within Rosaceae family. Hundreds of tree and shrub species have been described within it, along with an unknown number of subspecies, varieties and hybrids, partly of medicinal interest and in some cases also with edible fruits. According to recent studies, Sicily – an island in the center of the Mediterranean – constitutes a biodiversity hotspot for this genus in Italy. In this article the authors outline the biological diversity of Sicilian populations recognized at various taxonomic levels. In addition to the known specific and infraspecific taxa, two new species are described: Crataegus drepanensis and Crataegus zichichii. Also, the results of recent studies on the biological activity of extracts of flowers or fruits of some Sicilian populations of hawthorn investi- gated so far are recalled, thus proving that they represent a valuable resource of natural health prod- ucts. Regarding one of the described species (C. zichichii), on the basis of the environmental and landscape value it possesses – as well as decorative – a possible enhancement of it in the forest nurs- ery field and in urban greenery is advocated. Finally, in view of the dangers to which the populations are subjected – particularly that of C. drepanensis – ways of in situ and ex situ conservation are envisaged, and for this possible actions to be implemented are proposed.