Phylogenetic analyses of New Caledonian Metrosideros and Carpolepis (Myrtaceae) from nrDNA (ITS) sequences

Abstract

We have analysed the phylogenetic relationships of all known species in the genera Metrosideros and Carpolepis (Myrtaceae) from New Caledonia. Variation in nucleotide characters from the internally transcribed spacers of nuclear ribosomal DNA was used to construct parsimony and neighbour-joining phylogenies. These show that there is a large measure of congruence between the existing morphological taxonomy for those species and the relationships inferred from analyses of sequence variation. However, the DNA analyses suggest that Carpolepis may have only equal ranking to the infrageneric Metrosideros clades. The DNA analyses also nest M. tetrasticha among the species of subg. Metrosideros, as opposed to its present classification as a monotypic section (Neocaledonica) within subg. Mearnsia. On the basis of these findings, and of the observed differentiation shown in the analyses between the sectional clades Calyptropetala and Mearnsia of subg. Mearnsia, equivalent rankings may be appropriate for four infrageneric clades in Metrosideros. These four are currently classified as the genus Carpolepis (three species), and subg. Metrosideros (seven species), subg. Mearnsia sect. Mearnsia (five species) and subg. Mearnsia sect. Calyptropetala (five species) within Metrosideros.