Distribution and Conservation Assessment of Douepea arabica (Brassicaceae)

Douepea arabica (Hedge & Kit Tan) O.Appel & Al-Shehbaz is a rare and threatened subshrub species endemic to Saudi Arabia. In autumn 2024, a survey of the greater Jabal Qaraqir area of Prince Mohammed bin Salman Royal Reserve (PMBSRR) in northwestern Saudi Arabia was conducted, during which all specimens of D. arabica observed were recorded. In total, 932 D. arabica individuals were recorded from 48 fragmented populations at altitudes of 580 to 1245 m above sea level (m a.s.l.). These data were utilised to determine the species’ extent of occurrence (EOO) of 229.4 km2 and area of occupancy (AOO) of 128 km2. While these records expand the previously recorded distribution, the EOO and AOO are still quite small for this geographically restricted species. The primary threats to D. arabica are mainly anthropogenic, with habitat fragmentation and loss due to development and overgrazing by pastoral livestock key contributors. Utilising the data recorded from this survey as well as past research, the authors conclude that D. arabica should be classified globally as Endangered, based on the IUCN Red list criteria B1ab(iii), B2ab(iii), and C2a(i). As such, conservation programmes that integrate both in situ and ex situ methods are recommended to ensure the survival and prosperity of this rare endemic species.