Amorphophallus mangelsdorffii is described as a species new to science and illustrated. It is closely related to A. antsingyensis as indicated by the spiny (echinate) pollen exine, and both are more closely related to each other than to the other three endemic species of Madagascar. A. mangelsdorffii differs from A. antsingyensis mainly by the small stigma, much shorter pollen exine spinulae, a reflexed and twisted spathe lamina, a much less dissected leaf blade with relatively large leaflets and, in contrast to all other Malagasy species, its flowering simultaneous with the leaf at the end of the rainy season. A key to all Malagasy species of Amorphophallus is provided.
Willdenowia is an international peer-reviewed journal publishing original research papers in English from the entire fields of plant, algal and fungal systematics, covering the evolution, taxonomy and nomenclature of these organisms as well as related fields such as floristics and plant geography. Three issues appear each year (in April, August and December) in an open-access online edition and a print edition. Individual papers may be published in the online edition as fast-track articles ahead of inclusion in these issues.