Phylogenetic analysis of Eucalyptus informal subgenus Symphyomyrtus section Maidenaria

Abstract

Eucalyptus informal subgenus Symphyomyrtus section Maidenaria includes 86 currently recognised taxa endemic to south-eastern Australia. Cladistic methodology and a morphological data set have been used to examine the phylogenetic relationships of these taxa and an additional two unnamed forms that may be worthy of taxonomic recognition. Maidenaria may be defined as a monophyletic group by the presence of oil glands in the phloem, although this feature is not unique to the group. Informal series Ovatae is paraphyletic, having been defined by plesiomorphic features such as petiolate juvenile leaves. Informal series Vitninales is monophyletic, defined by juvenile leaves that are opposite, sessile and cordate for many nodes. The analysis was a difficult one because of a high level of homoplasy (82%), problems with intergrading complexes of taxa, and coding of characters that are continuously varying. The cladogram produced for Maidenaria can be viewed as a statement of the pattern of variation of morphological characters in the group. It is likely to be only an approximate representation of the phylogeny due to problems of character coding.