Recent fieldwork in Namibia has led to the discovery of two undescribed species of Ruellia, Ruellia acetabula and Ruellia kaokoana. These taxa are described and illustrated. Additionally, new lectotypifications are proposed for Ruellia marlothii and Ruellia diversifolia. Some specimens previously identified as Ruellia diversifolia are ascribed to the two new species. A revised checklist and a key to distinguish the nine species of Ruellia native to Namibia plus the Angolan R. diversifolia are provided. Keywords: Africa, discovery, new species, Ruellieae, sympatry, systematics.