Revision of the Malesian and Thai species of Sauropus (Euphorbiaceae: Phyllanthoideae)

Fourteen species of Sauropus are recognised for Malesia, 21 for Thailand. Two species are described as new, S. asymmetricus of Sumatra and S. shawii of Borneo. Many new synonyms, especially for S. androgynus and S. rhamnoides, are provided. The latter two species have a much wider distribution than described before and both are difficult to separate from each other. A phylogeny based on morphological and palynological data proved futile, but showed that Sauropus together with Breynia and Glochidion are embedded in the paraphyletic Phyllanthus. Most species which formerly belonged to Synostemon and are now included in Sauropus are probably, with the exception of S. bacciformis, related to Breynia and Glochidion. Because of the poor phylogenetic results the circumscription of Sauropus is not changed (Synostemon still included), and an infrageneric classification is not provided.