Hieracium gulianum, a new hawkweedspecies from limestone rocks around Geulhem, the Netherlands

Hieracium gulianum is described as a new species from the Netherlands. The description is accompanied by illustrations. The species is only known from a very restricted area near Geulhem and Valkenburg in South Limburg, where it occurs in open vegetation on steep limestone cliffs in the valley of the River Geul. The total number of individuals is estimated as being less than 200. Hence, the species is considered critically endangered according to the IUCN criteria. Hieracium gulianum faces two main threats: succession of the open vegetation in which the two populations occur and vegetation clearance of the rock faces in Geulhem.. We strongly plea for a special action plan to ensure the biodiversity value of the limestone cliffs in South Limburg, which provide a habitat that is very rare in the Netherlands.