Four new species of the tribe Vanguerieae (Rubiaceae) from southern, southwestern and western Madagascar are described and illustrated. Two species belong to the genus Pyrostria Comm. ex Juss.: P. costata Klack. & Razafim. with small leaves and distinctly ribbed pollen presenters and fruits, and P. macrocarpa Klack. & Razafim. characterized by its large, obconical, 5 – 6-lobed fruits. The other two species belong to the Malagasy subendemic genus Peponidium Ar.nes: P. leroyi Klack. & Razafim., characterized by hairy leaves with ciliate margins, sparsely pubescent flowers and ribbed pollen presenters, and P. sessile Klack. & Razafim., distinct by its cordate almost sessile leaves and double-tipped corolla lobes. Risk of extinction assessments for all four species are presented, as well as the respective distribution maps.