A new Cotyledon is described from the Tanqua Karoo in the Western Cape. Cotyledon tanquana is a distinct succulent shrublet from the lower eastern slopes of the Cedarberg Mountains and rocky terrain in the Succulent Karoo. It differs from Cotyledon orbiculata var. orbiculata by its distinctly cuneiform glandular hairy dull-green leaves and short dull-reddish corolla tube 15–17 × 5–8 mm bearing horizontally spreading transversely oblong yellowish squamae 2 × 1 mm, truncate at the apex.