A nomenclatural history for Plectorrhiza purpurata (Orchidaceae)

The nomenclatural history of the Australian epiphytic orchid Plectorrhiza purpurata (Rupp) M.A.M.Renner is reviewed. The first name published for this species, Cleisostoma gemmatum Rupp, is illegitimate, and Rupp proposed a replacement name, Cleisostoma purpuratum Rupp, shortly thereafter. Though the replacement was somewhat obliquely worded, Rupp fulfilled the requirements of the International Code of Nomenclature for algae, fungi, and plants, such that Cleisostoma purpuratum was available to serve as the basionym for the name generally used for this orchid since 1967, i.e. Schistotylus purpuratus (Rupp) Dockrill. The transfer of this taxon to Plectorrhiza under the new name Plectorrhiza gemmata M.A.Clem., D.L.Jones & D.P.Banks resulted in the publication of a superfluous name, because the earliest legitimate epithet purpurata is available in Plectorrhiza and ought to have been adopted. The required new combination is made