Abstract:
Phylogenetic relationships within tribe Phyllantheae, the largest tribe of the family Phyllanthaceae, were examined with special
emphasis on the large genus Phyllanthus. Nuclear ribosomal ITS and plastid matK DNA sequence data for 95 species of tribe
Phyllantheae, including representatives of all subgenera of Phyllanthus (except Cyclanthera) and several hitherto unplaced
infrageneric groups, were analyzed. Results for ITS and matK are generally concordant, although some species are placed
differently in the plastid and ITS trees, indicating that hybridization/paralogy is involved. Results confirm paraphyly of
Phyllanthus in its traditional circumscription with embedded Breynia, Glochidion, Reverchonia, and Sauropus. We favor the
inclusion of the embedded taxa in Phyllanthus over further generic segregation. Monophyletic Phyllanthus comprises an
estimated 1269 species, making it one of the ‘‘giant’’ genera. Phyllanthus maderaspatensis is sister to all other species of
Phyllanthus, and the genus appears to be of paleotropical origin. Subgenera Isocladus, Kirganelia, and Phyllanthus are
polyphyletic, whereas other subgenera appear to be monophyletic. Monotypic Reverchonia is sister to P. abnormis, arborescent
section Emblica to herbaceous Urinaria, free-floating aquatic P. fluitans to the weed P. caroliniensis, and the phyllocladous
section Choretropsis to the delicate leafy P. claussenii. The unique branching architecture known as ‘‘phyllanthoid branching’’
found in most Phyllanthus taxa has been lost (and/or has been derived) repeatedly. Taxonomic divisions within Phyllantheae
based on similar pollen morphology are confirmed, and related taxa share similar distributions. We recommend recognition of six
clades at generic level: Flueggea s.l. (including Richeriella), Lingelsheimia, Margaritaria, Phyllanthus s.l. (including Breynia,
Glochidion, Reverchonia, and Sauropus), P. diandrus, and Savia section Heterosavia.
