A new species of Multidentia (Rubiaceae) from central Africa

Background - The genus Multidentia Gilli (Rubiaceae-Vanguerieae) includes nine species from tropical Africa. A tenth species, M saxicola O.Lachenaud & Sene, is here described and illustrated. Methods - Classical methods of herbarium taxonomy have been applied. Key results - Multidentia saxicola occurs in Cameroon and in D.R.Congo; it is only known from two localities about 1,500 km apart. It most closely resembles M sclerocarpa (K.Schum.) Bridson from Tanzania but differs in the nearly unlobed calyx and lenticellate fruits. It differs from M dichrophylla (Mildbr.) Bridson in having much larger calyces and fruits and in being a taller tree (12-20 m). Multidentia saxicola is evaluated to be Critically endangered (CR B2ab(iii)) according to IUCN criteria. A key to the central African species of Multidentia is presented.