Taxonomy, phylogeny, and geography of Neoscortechinia Hook. f. ex Pax (Euphorbiaceae)

Six species are recognized in Neoscortechinia, two more than before, because N. angustifolia is raised to species level and N. forbesii is split into N. philippinensis (new combination) and N. forbesii s.s. The varieties of N. kingii are united. The genus Cheilosa, which closely resembles Neoscortechinia, is kept separate and it is used as the outgroup in the cladistic analysis of Neoscortechinia. The latter analysis resulted into a cladogram, which shows a first branching off of the sister species N. angustifolia and N. sumatrensis, followed by a subsequent branching off of N. nicobarica, N. philippinensis, and finally N. forbesii and N. kingii. Four of the six species show a wide-spread distribution in W Malesia ( N. kingii, N. nicobarica, N. philippinensis, and N. sumatrensis) and N. forbesii is wide-spread in E Malesia. Only N. angustifolia has an endemic distribution (NE Borneo) and is vicariant with its sister species. The distribution of N. forbesii may be due to dispersal combined with a vicariance event.