Hieracium petrocastellanum, sp. nov., and Other New Records in the Genus Hieracium (Asteraceae) from the Pollino National Park (Southern Italy)

Hieracium L. s. str. is a taxonomically critical genus of perennial herbaceous plants widely distributed across temperate regions of Europe, Asia, and North America. In Italy, its diversity is mainly concentrated in the Alps and northern Apennines, whereas southern Italy hosts only a limited number of relict taxa. Recent floristic surveys conducted in the Pollino National Park (southern Italy) revealed the presence of five Hieracium taxa, which were subsequently subjected to critical taxonomic evaluation. Detailed morphological analyses, supported by original herbarium comparisons and multivariate morphometric analyses, resulted in the description of a new species, here named H. petrocastellanum, the confirmation of H. pallescens subsp. tephrochlorum in the Italian flora after nearly 130 years from its discovery, and the first record for the Pollino area of H. symphytifolium, previously considered endemic to the Madonie Mountains (north-central Sicily), as well as H. pellitum subsp. pellitum and H. caesioides subsp. caesioides. The new species, Hieracium petrocastellanum, differs in having basal leaves with cuneate bases, only 0–1 cauline leaves, and bracts with sparse simple hairs and moderately dense glandular hairs. Ecological information and data on taxonomic relationships are also provided. The conservation status is assessed for H. petrocastellanum, H. pallescens subsp. tephrochlorum, and H. symphytifolium. An analytical key is presented to distinguish the new species from its closest relatives. These results confirm the Pollino National Park as a biodiversity hotspot and improve current knowledge of Hieracium.