This 10 céntimos stamp was issued by Spain in 1966 for Día del Sello (Stamp Day), featuring the elusive Water Chevrotain (Hyemoschus aquaticus), native to Central and West Africa. Released for Rio Muni, then a Spanish-administered territory, the design highlights the species’ delicate form and spotted coat in fine engraved detail by F.N.M.T. The stamp belongs to a popular wildlife topical series and remains sought after for its clean typography, colonial-era postal history, and attractive zoological illustration. A desirable addition for collectors of African fauna, Spanish territories, and 1960s commemoratives.