Phylogenetic relationships of Cyrillaceae and Clethraceae (Ericales) with special emphasis on the genus Purdiaea Planch

Abstract

The phylogenetic relationships and systematic position of the three genera of Cyrillaceae (Ericales), Cyrilla, Cliftonia, and Purdiaea, were investigated by jackknife analysis of a combination of DNA sequences from the plastid genes atpB, ndhF, and rbcL. The results show that Cyrilla and Cliftonia together are the sister group of Ericaceae, whereas Purdiaea groups with Clethra of Clethraceae. Together, Clethra and Purdiaea form the sister group of ( Cyrilla+ Cliftonia)+Ericaceae. It is concluded that Purdiaea should be moved to Clethraceae. A cladistic analysis based on morphological data was performed to investigate relationships among the species of Purdiaea. The results indicate that Purdiaea belizensis from Central America is sister to all other species of the genus, and that Purdiaea nutans from northern South America is sister to the remaining group of species which are all Cuban endemics, among which P. cubensis from Pinar del Rio in western Cuba is sister to the eight species occurring in the Oriente province in eastern Cuba.