A phylogenetic classification of the Malesian Hippomaneae (Euphorbiaceae)

The delimitation of genera of the tribe Hippomaneae in the Euphorbiaceae has never been solved satisfactorily. The species of this tribe present in the Malay Archipelago (Malesia) were recently revised, but no satisfying generic classification was available. Therefore, a partial phylogenetic analysis of the Malesian Hippomaneae was performed. The delimitation of genera after the analysis was done as conservatively as possible, with only those monophyletic genera distinguished that possessed unique apomorphies within the whole of the Hippomaneae. The genera recognized are not likely to be altered in a more elaborate analysis of the complete Hippomaneae. For this reason the use of a partial analysis for generic delimitations seems justified and presents, when carefully executed, a procedure with which the value of larger regional flora revisions can be greatly improved. The analysis resulted in eight trees, all pointing to the same generic delimitation. Before the analysis 12 groups could be distinguished, but after the analysis it was apparent that only 11 of them constituted monophyletic groups. Two new genera will have to be described, some others will have to be united, and several old delimitations, already abolished for some time, will have to be reestablished. Most remarkable are the union of Excoecaria with Glyphostylus and Sebastiania; and the position of Gymnanthes near taxa formerly attributed to Sapium.