This 40 céntimos commemorative stamp was issued in 1966 by Spain for Río Muni (Spanish Guinea) to celebrate the Día del Sello (Stamp Day). The design features the giant pangolin (Smutsia gigantea), a rare, scaly anteater native to West and Central Africa, shown curled around a tree branch. Printed by the F.N.M.T. (Fábrica Nacional de Moneda y Timbre) in Madrid, it highlights the rich biodiversity of the region while promoting philately. Today, this issue holds special interest for collectors of colonial Africa, fauna-themed stamps, and Spanish overseas territories.