Two new threatened species of Benstonea Callm. & Buerki (Pandanaceae) from Sabah (Borneo, Malaysia)

Two new species of Benstonea Callm. & Buerki (Pandanaceae) are described from Sabah (Borneo, Malaysia). Benstonea fortuita Callm. & Buerki is only known from a small patch of forest in the southern tip of Crocker Range in the southwest of the state. It is diagnosed by its subacaulescent habit, its leaves abruptly attenuate at the apex and narrowing towards the base, and its solitary globose syncarp on a short peduncle. Benstonea serpentinica Callm. & Buerki is endemic to the ultramafic substrate of Mt. Silam in eastern part of the state ; it is diagnosed by its lateral plurisyncarpic infructescence, its peduncle covered with prophylls at base, and its stout acuminate style. Discussions on the morphological and molecular phylogenetic affinities of the new species are provided. Finally, both new species are assessed as “Critically Endangered” following IUCN Red List Categories and Criteria.