A molecular phylogeny of Celtidaceae and Ulmaceae (Urticales) based on rbcL nucleotide sequences

On the basis of 1,290 bp sequences of the chloroplast gene rbcL, a molecular phylogeny of seven of nine genera of the Celtidaceae and four of six genera of the Ulmaceae was produced. These data were analyzed together with some other urticalean genera using three methods (i.e., maximum parsimony, maximum likelihood, and neighbor joining methods). Maximum likelihood topology among 18 trees obtained indicated that the Urticales are monophyletic with its common clade splitting basally into two: one leading to a line comprising Ampelocera (traditionally placed in Celtidaceae) and Ulmaceae, and the other leading to a line comprising the remaining genera of Celtidaceae, Moraceae, and other Urticales. Ulmaceae, to which Ampelocera is a sister group, are monophyletic, as supported by many lines of morphological evidence. In contrast to Ulmaceae, the monophyly of Celtidaceae (excluding Ampelocera) was not supported, and resolution of relationships of Celtidaceae with other Urticales, as well as of those within the family, is left for future study.