A new species of stringybark, Eucalyptus mackintii, from eastern Victoria and its phenetic and cladistic relationships

Abstract

Populations of stringybark trees from East Gippsland, with affinities to Eucalyptus macrorhyncha, were studied by pattern analyses of adult and seedling morphology, leaf volatile oils and flavonoid composition. They had previously been determined as hybrids, or as referable to an undescribed taxon. Samples of E. deuaensis, E. globoidea, E. macrorhyncha and E. muelleriana were included to assess the affinities of E. aff. macrorhyncha to other stringybark taxa. No evidence was found to support a hybrid origin of E. aff. macrorhyncha, and it is described as E. mackintii sp. nov.

In adult morphology E. mackintii is similar to, but distinct from E. macrorhyncha, whereas in seedling morphology the two are indistinguishable. Two chemical forms of E. mackintii were detected in the leaf volatile oils, both of which have also been reported to occur in E. deuaensis and E. macrorhyncha. The leaf flavonoid composition of the new species is similar to that of E. macrorhyncha, although some differences between the two were observed. The inclusion of E. mackintii in a cladistic analysis of the informal superseries Capitellaticae Ladiges & Humphries resulted in the taxon forming an unresolved basal trichotomy within the infraseries Capitllatae.