Systematics Section / ASPT
Kathriarachchi, Hashendra , Samuel, Rosabelle , Hoffmann, Petra , Wurdack, J.Kenneth , Stuessy, Tod F. , Chase, Mark W. .
Phylogenetic relationships in the subtribe Flueggeinae (Phyllanthaceae) with emphasis on genus Phyllanthus: Evidence from nuclear ITS and plastid matK sequences.
Phyllanthus (c. 850 spp.) is the largest genus of Phyllanthaceae. The high species number (including many very similar pantropical weeds) paired with minute unisexual flowers make this a taxonomically challenging group. The current classification by Webster is mainly based on diverse vegetative architecture, pollen and floral morphology. Sequence data from rbcL have shown that Phyllanthus is paraphyletic, with Breynia, Glochidion, Reverchonia and Sauropus (totalling a further c. 450 species) embedded, but sampling and resolution have so far been unsatisfactory. This study analyzes ITS and matK sequence data of subtribe Flueggeinae including all the above genera, and representatives of all eight subgenera of Webster’s (1956) first (mainly neotropical) classification of Phyllanthus, as well as of the palaeotropical subgenera Emblica and Gomphidium and several undescribed and hitherto unplaced infrageneric groups (at least 24 sections). The resulting trees are well resolved and confirm the paraphyly seen with rbcL. Subgenera Isocladus, Kirganelia and Phyllanthus are polyphyletic, whereas other subgenera appear monophyletic. The unique architecture (‘phyllanthoid branching’) of Breynia, Glochidion, Reverchonia, Sauropus and most Phyllanthus taxa has evolved (or/and been lost) several times independently (e.g., subgenus Phyllanthus section Urinaria is sister to subgenus Isocladus section Loxopodium as suggested by Webster 1956 and 1957). Taxonomic divisions based on similar pollen morphology are confirmed, and related taxa share similar geographic distributions.
1 - University of Vienna, Institute for Botany, Dept. of Higher Plant Systematics and Evolution, Rennweg 14, Vienna, A-1030, Austria
2 - Smithsonian Museum Support Centre, Laboratories of Analytical Biology, 4210 Silver Hill Road, Suitland, Maryland, 20746, USA
3 - Royal Botanic Gardens, Kew, Jodrell Laboratory, Richmond, Surrey, TW9 3AB, UK
4 - Royal Botanic Gardens, Kew, Herbarium, Richmond, Surrey, TW9 3AB, U.K.
Presentation Type: Paper
Location: Cottonwood B (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 9:00 AM