Revision and Phylogeny of subtribes Chrozophorinae and Doryxylinae (Euphorbiaceae) in Malesia and Thailand

A phylogeny of the complete tribe Chrozophoreae is presented in order to establish the possible monophyly and relationships in subtribes Chrozophorinae (Chrozophora) and Doryxylinae ( Doryxylon, Melanolepis, Sumbaviopsis, Thyrsanthera). Added are the other subtribes in tribe Chrozophoreae, the Speranskiinae (Speranskia) and Ditaxinae ( Argythamnia, Caperonia, Chiropetalum, Ditaxis, Philyra). Outgroups are the genera Agrostistachys and Chondrostylis (tribe Agrostistachydeae). The phylogeny shows two monophyletic groups, subtribe Speranskiinae together with Ditaxinae, and subtribe Chrozophorinae with Doryxylinae. The latter group is statistically well supported by a high bootstrap value. The first group is weakly supported and collapses easily when the characters are selected somewhat differently. The former subtribes Chrozophorinae and Doryxylinae are united into one subtribe, Chrozophorinae. The remaining taxa in tribe Chrozophoreae, the monogeneric subtribe Speranskiinae and subtribe Ditaxinae are united into subtribe Ditaxinae. Within subtribe Chrozophorinae s.l. Chrozophora is sister taxon to all other taxa, followed by Thyrsanthera and Melanolepis. Doryxylon and Sumbaviopsis were apparently the last to separate. The differences between all, mainly monotypic, genera are quite large, therefore, the present delimitation is favoured over a suggested union of Doryxylon and Sumbaviopsis.