Urtica longifolia Burm. f. (1768) is the oldest available name known for Debregeasia velutina Gaudich. (≡ Debregeasia longifolia (Burm. f.) Wedd.), the type of the genus Debregeasia Gaudich. However, the previous assumption regarding the holotype of Urtica longifolia is incorrect and is here clarified. An incomplete specimen from Burman’s herbarium at G is shown to be part of the original material, but does not show all diagnostic characters referred to in the protologue and now necessary to distinguish D. longifolia from other species of that genus. It is designated lectotype, and an epitype, Jacobs 8058 (K), is designated to secure current usage. The confusing nomenclatural history of Missiessya in relation to Debregeasia is reviewed: “ Missiessya ” was invalidly published by Gaudichaud in 1847–1848; Weddell validly published it as an illegitimate superfluous name in 1854 and later (1857) as an illegitimate later homonym.