A revision of the Malesian monotypic genus Cheilosa Blume (Euphorbiaceae)

The West Malesian genus Cheilosa Blume has been revised; the variability of the only species, C. montana Blume, will be described. Cheilosa montana combines the two former species C. montana and C. malayana (Hook. f.) Airy Shaw. Typical for Cheilosa are the presence of glands in the teeth of the leaves; thyrsoid, mainly unbranched, ramiflorous to terminal inflorescences; absence of petals; the presence of a disc; 9 or 10 stamens; 3- (rarely 4)-locular ovaries with one ovule per locule; thick-walled fruits; an aril around the seed; and endosperm. Fascicled hairs are usually present on the lower surface of the leaves, but are caducous. The excluded C. whiteana Croizat is provisionally transferred as a new species to Trigonostemon by Airy Shaw.