Two fossil species of Metrosideros (Myrtaceae) from the Oligo-Miocene Golden Fleece locality in Tasmania, Australia

<p><strong>Premise of the Study:</strong> The capsular-fruited genus <i>Metrosideros </i>(Myrtaceae) is one of the most widely distributed flowering plant genera in the Pacific but is extinct in Australia today. The center of geographic origin for the genus and the reason for and timing of its extinction in Australia remain uncertain. We identify fossil <i>Metrosideros </i> fruits from the newly discovered Golden Fleece fossil flora in the Oligo-Miocene of Tasmania, Australia, shedding further light on these problems.</p> <p><strong>Methods:</strong> Standard paleopalynological techniques were used to date the fossil-bearing sediments. Scanning electron microscopy and an auto-montage camera system were used to take high-resolution images of fossil and extant fruits taken from herbarium specimens. Fossils are identified using a nearestliving-relative approach.</p> <p><strong>Key Results:</strong> The fossil-bearing sediments are palynostratigraphically dated as being<i> Proteacidites tuberculatus </i>Zone Equivalent (ca. 33-16 Ma) in age and provide a confident Oligo Miocene age for the macrofossils. Two new fossil species of <i>Metrosideros </i> are described and are here named <i>Metrosideros dawsonii </i>sp. nov. and <i>Metrosideros wrightii </i>sp. nov.</p> <p><strong>Conclusions:</strong> These newly described fossil species of <i>Metrosideros</i> provide a second record of the genus in the Cenozoic of Australia, placing them in the late Early Oligocene to late Early Miocene. It is now apparent not only that <i>Metrosideros</i> was present in Australia, where the genus is now extinct, but that at least several <i>Metrosideros</i> species were present during the Cenozoic. These fossils further strengthen the case for an Australian origin of the genus.</p>