Abstract
Gnetum L. is a genus of economic importance distributed in the humid rainforests of Central Africa. The African species of Gnetum are dioecious climbers and only two species (Gnetum africanum Welw. and G. buchholzianum Engl.) have been described previously. The names G. africanum and G. buchholzianum have been applied interchangeably to similar morphological forms of Gnetum specimens in Africa or on duplicates of specimens causing taxonomic confusion. The nomenclature of Gnetum species in Africa is thus in need of reappraisal. Morphological descriptions are based on examination of over 300 specimens from various herbaria, mainly B, BR, FHI, J, K, LISC, P, PRE, WAG and YA. The original applications of the names Gnetum africanum and Gnetum buchholzianum are clarified and two new African species (Gnetum interruptum E.H. Biye sp. nov. and Gnetum latispicum E.H. Biye sp. nov.) are described on the basis of morphological features. A key to the African species is provided and the main characters, such as the shape and size of spike that are essential in the recognition of species in the genus Gnetum in Africa as well as the importance of conservation are discussed. These species are assessed as threatened and at a high risk of global extinction according to the IUCN Red List categories and criteria, and are in need of conservation measures for their protection.
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Acknowledgments
The authors are grateful to the curators of the cited herbaria and to partners of Aluka initiative (http://www.aluka.org) for access to specimens and/or digital images of types, to Donald McCallum and anonymous reviewers for valuable suggestions that improved this paper and to Lesley Deysel for illustrations of the four species of Gnetum in Africa.
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Biye, E.H., Balkwill, K. & Cron, G.V. A clarification of Gnetum L. (Gnetaceae) in Africa and the description of two new species. Plant Syst Evol 300, 263–272 (2014). https://doi.org/10.1007/s00606-013-0879-6
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DOI: https://doi.org/10.1007/s00606-013-0879-6