We report the discovery of the third known specimen of Coluber zebrinus  2000 and fifth known specimen of Prosymna visseri, 1959 from north-western Namibia. The new material is described. The distributions of both of these rare colubrids appear to be reflective of a previously undocumented mopane savanna area of endemism stretching from the Kamanjab region of Namibia to south central Angola and beyond. A similar distribution is shared by numerous other reptiles. Keywords: Reptilia: Squamata: Serpentes: Colubridae: Prosymna visseri, Coluber zebrinus, Kunene River, Mopaneveld, biogeography, Namibia.