Tibouchina spp. (Melastomataceae) are native to South America, but have been planted as ornamentals in many southern hemisphere countries. The Melastomataceae are members of the Myrtales and are close relatives of the Myrtaceae, to which the genus Eucalyptus belongs. The recent discovery of several Chrysoporthe spp. on Tibouchina spp. has prompted a more detailed survey for other Eucalyptus pathogens that might occur on this tree. In this study, the discovery in Australia of Holocryphia eucalypti, a Eucalyptus pathogen, on diseased stems of Tibouchina urvilleana is reported. Characterisation of this fungus was based on morphology and comparisons of β-tubulin gene sequences. Greenhouse pathogenicity tests, including isolates of H. eucalypti from Eucalyptus spp. in Australia and South Africa, showed that the isolates of H. eucalypti from T. urvilleana were significantly more pathogenic on T. urvilleana than isolates from Eucalyptus.