Re-shaping spurge pioneers : circumscription, taxonomy and phylogeny of Mallotus (Euphorbiaceae s.s.)

Abstract

The thesis focuses on the tropical plant genus Mallotus. This genus belongs to the Euphorbiaceae (spurge family), and comprises c. 110 species. These species are mainly found in (sub)tropical Asia and the West Pacific, with only two species in Africa and Madagascar. Mallotus and its sister genus Macaranga are important components of the forest vegetation of Southeast Asia and show a large variety of life-history strategies (both pioneer and climax). Most Mallotus species are shrubs or trees, seldom climbers. The variable morphology of these species has resulted in three main subgeneric classifications, of which the latest recognizes eight sections. The study presented here was part of a large project involving ecological, revisional and phylogenetic work on Mallotus. Five of the eight sections of the genus Mallotus were revised in the framework of the Flora Malesiana project, hereby provisionally accepting the sectional division of Airy Shaw (1968). The remaining three sections were already revised in a previous study. The monophyly of all eight sections and their evolutionary relationships were analyzed using morphological and molecular data (the chloropast gene matK and the nuclear gene gpd). Finally, the phylogenetic significance of the morphological characters used in the classification by Airy Shaw

was evaluated.