Psychotria pendens (Rubiaceae, Psychotrieae), a new ultramafic species from Central Palawan, Philippines

Psychotria pendens from the lowland ultramafic forest of Mt. Victoria, Palawan Island, Philippines is herein described as a new species of Rubiaceae. The new species is morphologically similar to P. rubiginosa (Gitingensis species group) by having monochotomous inflorescence and oblanceolate to oblong-elliptic leaves but is distinguished by its large, leaf-like, valvate stipules with biattenuate to biacuminate tips, pendent inflorescence, glabrous abaxial leaf surface, narrowly triangular bracts, and glabrous calyx. Molecular analysis revealed that this newly discovered species belongs to the Pacific Psychotria clade, and is allied to the Philippine species P. luzoniensis and Hawaiian species P. mariniana. The species is assessed as Critically Endangered (CR) based on the IUCN Red List categories and criteria.