Taxonomy and biogeography of Australian Rozites species mycorrhizal with Nothofagus and Myrtaceae

Abstract

Seven species of the putatively obligately ectomycorrhizal fungal genus Rozites are described from Australian Nothofagus and myrtaceaeous forests. Rozites metallica, R. armeniacovelata, R. foetens, and R. occulta are new species associated with Nothofagus in south eastern Australia. Rozites fusipes, previously known only from New Zealand, is reported from Tasmanian Nothofagus forests. Rozites roseolilacina and R. symea are new species associated with Eucalyptus in south eastern and south western Australia respectively. The significance of these Rozites species to mycorrhizal and biogeographical theories, such as the origin of ectomycorrhizal fungi associated with myrtaceous plants in Australia are discussed. The diversity of Rozites species in Australia, which equals or exceeds that of other southern regions, furthers the notion that many species of the genus co-evolved with Nothofagus in the Southern Hemisphere. Rozites symea in Western Australia occurs well outside the current geographic range of Nothofagus. It is considered to be a relict species that has survived the shift in dominant ectomycorrhizal forest tree type from Nothofagus to Myrtaceae (local extinction of Nothofagus 4–5 million years ago), and is most likely now confined to the high rainfall zone in the south west. Data on Rozites in Australia support the concept that at least some of the present set of ectomycorrhizal fungi associated with Myrtaceae in Australia are those which successfully completed a host change from Nothofagus, and adapted to changing climate, vegetation and soil conditions during and since the Tertiary. We suggest that the ancient stock of Rozites arose somewhere within the geographical range of a Cretaceous fagalean complex of plant taxa. By the end of the Cretaceous, Rozites and the fagalean complex may have spanned the Asian–Australian region including perhaps many Southern Hemisphere regions. A northern portion of the ancestral Rozites stock gave rise to extant Northern Hemisphere Rozites species and a southern portion speciated as Nothofagus itself speciated.