Alpinia koshunensis Hayata was first publicized in 1915. After that, most authors didn’t treat this species as a synonym of Alpinia formosana K. Schumann until 1978. Recently we checked the type of A. koshunensis Hayata, compared the original description and got more relevant materials. We confirm A. koshunensis Hayata is a unique species. A taxonomic treatment, color photographs, illustration, and distribution of this species are provided to aid the identification of this endemic
plant. A detailed comparison table between A. koshunensis Hayata and closely related species are also provided. Key words: Alpinia koshunensis; Zingiberaceae; Synonym; Taiwan; Plant taxonomy.