STONE, R. DOUGLAS* and BRUCE G. BALDWIN. University and Jepson Herbaria and Department of Integrative Biology, University of California, Berkeley, CA 94720. - ITS and ETS sequence data support the recognition of four Old World genera in Melastomataceae subfamily Memecyloideae.
Sequence variation in the internal and external transcribed spacers of
nuclear ribosomal DNA allows the first analysis of phylogenetic
relationships in the Melastomataceae subfamily Memecyloideae, a group
of shrubs and small trees with about 450 currently recognized species
and a pan-tropical distribution pattern. Earlier proposals to
recognize four paleotropical genera (Memecylon,
Spathandra, Lijndenia, and Warneckea) based on
morphological and anatomical evidence are strongly supported by this
molecular data set. Four east African taxa that had been transferred
to Lijndenia are shown to belong either to Memecylon
(M. fragrans, M. greenwayi, M. semsei) or to
Warneckea (W. jasminoides). Within the large and
widespread Old World genus Memecylon, the west African taxon
M. lateriflorum is strongly supported as sister to the
remaining taxa, corroborating the earlier-hypothesized trend toward
decreasing locule number in this group (ovaries 4-loculed in members
of sect. Mouririoidea versus unilocular in all other species of
Memecylon). Species groups in Memecylon from east
Africa, Madagascar, and Malesia are each well supported as
monophyletic, and the low sequence variation observed within the
Malagasy clade suggests that the high species diversity found on that
island is the result of a recent radiation.
Key words: ETS, ITS, Melastomataceae, Memecyloideae, molecular phylogeny, rDNA