Cladistic and Biogeographic Analysis of Western Australian Species of Eucalyptus L'Hérit., Informal Subgenus Monocalyptus Pryor & Johnson

Abstract

The Western Australian species of Eucalyptus informal subgenus Monocalyptus were shown to be a paraphyletic group. A cladistic analysis of a larger sample of taxa, using a Wagner parsimony method, showed that the Queensland species E. rubiginosa is the sister species to all others in Monocalyptus. The Western Australian species E. jacksonii and E. brevistylis were found to be connected to eastern taxa and are probably related to the lineages leading to the 'green ashes' and 'stringybarks' etc. The remaining Western Australian species formed a number of subclades, one of which, including E. marginata and E. staeri, had a separate connection with eastern species, probably all of the 'blue ashes'. A revised informal classification recognising three sections, five subsections, five infrasections, five superseries, five series and two subseries is presented. Biogeographic analyses of each of the major subclades are summarised as one area-consensus tree representing a classification of areas as determined from the taxonomy of the eucalypts. A comparison with the geological and climatological history points to the Tertiary as the likely time of first speciation within Monocalyptus.