Three new tribes in Myrtaceae and reassessment of Kanieae

Abstract

The current tribal classification of Myrtaceae was based on analysis of the plastid matK coding region within the trnK intron. The phylogenetic position of the genera Cloezia and Xanthomyrtus was poorly supported, and the original sequence for Kania, the type genus of the tribe Kanieae, was rather poor. To clarify relationships, we sequenced plastid psbA-trnH and an extended portion of the trnK intron, including the spacer regions flanking matK, and nuclear ribosomal ITS and ETS regions for representative species across the tribes, including denser sampling of the three genera of interest. Analyses of these extended datasets show a strong relationship between Kania and the tribe Metrosidereae but not with other genera presently assigned to the Kanieae. The relationship between Kania and the tribe Metrosidereae is strongly correlated with morphological features recently documented in Metrosideros fossils. Consequently, a new tribe, Tristaniopsideae PeterG.Wilson, is described to accommodate most genera presently assigned to Kanieae. Furthermore, the morphological divergence and genetic distance shown by Cloezia and Xanthomyrtus are here considered as justifying their recognition as the tribes Cloezieae Peter G.Wilson and Xanthomyrteae Peter G.Wilson. Recognition of these tribes brings to four the number of tribes absent from present-day mainland Australia. Prior to this study, Metrosidereae was the only tribe in subfamily Myrtoideae that was absent from mainland Australia.