Relationships in the Stringybarks, <i>Eucalyptus</i> L&amp;apos;hérit. Informal Subgenus <i>Monocalyptus</i> Series <i>Capitellatae</i> and <i>Olsenianae</i> : Phylogenetic Hypotheses, Biogeography and Classification

Abstract

The stringybark eucalypts form a monophyletic group characterised in Monocalyptus by hispid juvenile leaves. They have been analysed using a phenetic method, additive similarity trees and a cladistic parsimony method (Wagner trees). The shortest Wagner trees indicated that Eucalyptus muelleriana is the sister species to all other stringybarks. E. olsenii and a taxon from the Carnarvon Range (Queensland) are the next most plesiomorphic taxa in the phyletic sequence. The remaining taxa form a trichotomy: E. tindaliae, species with fruits &amp;gt; 8 mm in diameter and with the disc ascending, and species with fruits &amp;lt; 8 mm and with the disc level. Subclades are largely characterised by seedling morphology. A revised informal classification is presented, the group being treated as a superseries. A method of cladistic biogeography is explained and applied. The stringybarks are endemic to eastern mainland Australia plus Kangaroo Island, but not Tasmania, and the consensus area-cladogram suggests a sequence of seven historical events subdividing an ancestral area into eight smaller ones. Queensland appears to be the most plesiomorphic area.