The genus Clemensiella (Apocynaceae – Asclepiadoideae) is reported to include two species. Clemensiella mariae, a Philippine endemic, is redescribed, illustrated, and lectotypified. Its chromosome number (2n = 22) is reported for the first time. The recently described Hoya viracensis is synonymised with Clemensiella mariae. Clemensiella omlori is described as a new species from Borneo and Sumatra. The taxonomic relationship of Clemensiella to other genera of tribe Marsdenieae is discussed.