Phylogeny and systematics of Asian Schefflera species (Araliaceae): taxonomically useful morphological characteristics and their evolution

1 Moscow State University, Moscow, Russia
2 Russian-Vietnamese Tropical Center, Hanoi, Vietnam

Asian species of the genus Schefflera form a monophyletic group called Asian Schefflera Clade within the family Araliaceae. Though several systems of Asian Schefflera species were suggested during the twentieth century, recent investigations showed extensiveinfrageneric polyphyly. We studied the variation of a number of morphological characteristics within the Asian Schefflera Clade and clarified their evolution by mapping them onto our extended molecular phylogenetic tree. Our results indicate that the presence or absence of the septate cavity in stem pith is the only feature which agrees with dividing of Asian Schefflera Clade into two subclades and therefore can be used for description of two monophyletic sections. Then, several other features facilitate description of some minor monophyletic groups. One group differs by an unusual type of leaf blade. Three groups within Asian Schefflera Clade are characterized by polymerous flowers in contrast to other pentamerous species. The ancestral type of the inflorescence is a panicle of umbels, which changed twice into double raceme during the evolution of Asian Schefflera Clade. The evolution of styles in the gynoecium, a feature which was broadly used for subdivision of the genus Schefflera, is rather complicated: the ancestral state is the presence of the styles, once the styles were lost and then two cases of reversion to the presence of the styles occurred. Thus, the evolution of most morphological features within Asian Schefflera Clade appeared to involve more homoplasies (parallelisms and reversions) than it was previously supposed. Nevertheless, employing a complex of features will be helpful for description of monophyletic groups during elaboration of phylogenetic system of the genus Schefflera. The work was supported by the Russian Foundation for Basic Research (projects 12-04-31073 and 12-04-16130) and by the Ministry of Education and Science of Russia (FCP “Kadry”, State Contract NK-541P/P341).

© 2012 Organizing Committee