ABSTRACT.- The international spread of the myrtle rust pathogen, Austropuccinia psidii, can be largely attributed to the "pandemic" biotype that has more than 450 host species. However, within South America, the putative native range of A. psidii, multiple biotypes have been characterised, each with a restricted known number of hosts. These biotypes may pose a significant biosecurity threat to countries already affected by the pandemic biotype. Here, we report the susceptibility of four species of Myrtaceae from New Zealand, pohutukawa (Metrosideros excelsa), manuka (Leptospermum scoparium), kanuka (Kunzea ericoides), and rawiri manuka (Kunzea ericoides 'gumland ecotype'), to a strain of the Eucalyptus biotype of A. psidii. Symptoms and signs developed on inoculated plants of all species. Qualitative resistance phenotypes, with no disease development, were observed for all four species. However, no hypersensitive responses were observed. As seen for other biotypes, pohutukawa had the greatest susceptibility, while kanuka had the lowest. These findings are consistent with prior work, showing that the Eucalyptus biotype can infect a broader range of species than its field host association implies. As well as uredinia (asexual spores), telia (sexual spores) developed on several plants, indicating that these species could provide a universal host for sexual reproduction and outcrossing between biotypes. Knowledge that the Eucalyptus biotype of A. psidii is virulent on several indigenous New Zealand Myrtaceae will inform future biosecurity risk assessments. These findings highlight the need to develop diagnostics tools to differentiate between biotypes and allow rapid responses to potential future incursions. © 2025 Springer Nature