Abstract
Abstract Verbascum species have economic value as ornamental plants and in traditional medicinal uses. Sixteen species of Verbascum are recognized on the Arabian Peninsula, two of which comprise two varieties each, giving eighteen taxa in total. They are collectively widespread but often narrowly restricted individually, occurring in Saudi Arabia, Yemen, Oman, and the United Arab Emirates. In this study, in situ and ex situ conservation gap analyses of 18 Verbascum taxa found on the Arabian Peninsula were undertaken based on taxon richness and ecogeographic diversity using complementarity analysis. The results indicate that 30% of the Verbascum taxa population was found within protected areas (PAs), while 70% was found outside PAs. Verbascum taxa hotspots were identified in the northwest region of Tabuk Province and the southwest region of Asir Province in Saudi Arabia. In eight out of 26 ELC zones, ecogeographic diversity was observable both in complementary PAs and at complementary sites. The greatest diversity of Verbascum taxa was observed in PAs located in ELC Zones 19 and 25. Complementarity analysis identified six complementary PAs within the existing network and, at a resolution of 10 × 10 km, twelve complementary sites, of which eight lie within existing PAs and four outside them, indicating locations where other effective area-based conservation measures could be implemented. Because the two analyses used different selection units and their solutions overlap spatially, these totals are not additive. Only two of the eighteen Verbascum taxa of the Arabian Peninsula are represented in international or national genebanks, in each case by a single accession. Therefore, recommendations are provided in this study for active in situ and ex situ conservation methods that would aid in conserving the diversity of Verbascum taxa on the Arabian Peninsula.