The genus Goniothalamus (Annonaceae) in Sumatra

A comprehensive taxonomic revision of the species of Goniothalamus (Blume) Hook. f. & Thomson (Annonaceae) occurring in Sumatra and adjacent islands is presented for the first time. Fourteen species are recognized, including six endemics that are described as new to science ( G. acehensis, G. alatus, G. dewildei, G. loerzingii, G. longistaminus and G. miquelianus ). In addition, two species are newly recorded from Sumatra, viz. G. parallelivenius Ridl. (previously reported from Borneo), and G. wrayi King (previously reported from Peninsular Malaysia). The extensive nomenclatural confusion regarding the application of the names G. costulatus Miq. and G. opacus Bakh. f. is clarified: the names are shown to be synonymous, with the former having nomenclatural priority. The utility of specific taxonomic characters are also discussed, with particular emphasis on petal indumentum, staminal connective shape, ovary indumentum, stigma shape, monocarp size and shape, and seed indumentum. Biogeographical relationships in the genus are discussed, and the significance of the Barisan mountain range and the Quaternary volcanic tuffs around Lake Toba are highlighted as potential ecological barriers limiting dispersal.  © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society , 2002, 139 , 225–254.