Phylogeny of Melaleuca, Callistemon, and related genera of the Beaufortia suballiance (Myrtaceae) based on 5S and ITS-1 spacer regions of nrDNA

A phylogenetic analysis of genera within the informal suballiance Beauforti a (family Myrtaceae), largely endemic to Australia and New Caledonia, is pr esented based on separate and combined data sets for SS and ITS-1 spacer re gions of nuclear ribosomal DNA. The two sets were not in conflict but the 5 S data set was more informative. Data were analysed using conventional pars imony, jackknife parsimony, and three-item parsimony analyses. Three-item a nalysis gave more resolved trees than conventional parsimony analysis. The Beaufortia suballiance includes two major clades, with all Australian repre sentatives of Callistemon (shown to be monophyletic) and most Australian re presentatives of Melaleuca forming one of these. The sister clade comprises a well-defined group of endemic New Caledonian taxa (classified as Callist emon and Melaleuca), some Australian species of Melaleuca, a clade includin g the Western Australia/Northern Territory genera Beaufortia, Lamarchea, an d Regelia, and a clade including the south-west Western Australian genera C alothamnus, Eremaea, Conothamnus, and Phymatocarpus, All molecular analyses support the monophyly of Conothamnus and of Regelia, genera for which a nu mber of species were included. Three-item analysis of the combined data set supports the monophyly of Beaufortia. The findings have implications for b oth taxonomy and biogeography. (C) 1999 The Willi Hennig Society.