A new species of Leucas, here described as L. gypsicola A. J. Paton, Friis & Sebsebe, was collected in 2015, on gypsum outcrops of the Gorrahei Formation at the Lele Hills between Ginir and Imi, Oromia National Regional State, Ethiopia. The closest relatives of L. gypsicola are two species, which occur in the dry parts of Ethiopia and Somalia (L. abyssinica) and in the Rift Valley of Kenya (L. hirundinaris). Leucas gypsicola seems to be a narrow endemic, restricted to outcrops of gypsum dominated by the tree Commiphora guidottii in Acacia-Commiphora woodland and bushland east of the Ethiopian highlands, similar to the narrowly restricted ranges of two recently described species of Commicarpus, C. macrothamnus Friis & O. Weber and C. leleensis Friis & Sebsebe (Nyctaginaceae).