Gleichenia nagalingumiae sp. nov., a remarkably well-preserved fossil species with in situ spores from the Miocene of Australia

There are few well-documented members of the Gleicheniaceae from the Cenozoic. Most records are confined to Australia and New Zealand and of sterile material. Gleichenia nagalingumiae sp. nov. was found at McGraths Flat, a recently discovered fossil deposit in central New South Wales (Australia). In this Lagerstätte, fossil preservation in the iron hydroxide mineral goethite provides a remarkable level of subcellular detail. The sori of Gleichenia nagalingumiae sp. nov. occur in a distinct chamber within the lamina, a feature only seen in three extant members of this genus, one from Africa, Madagascar and the Mascarene Islands, another from New Zealand, and the third from Malesia. Gleichenia nagalingumiae sp. nov. is the first record of a taxon with sori in laminar pits from Australia. Recent molecular phylogenies place taxa with sori in laminar pits at the base of the Gleichenia clade. Our discovery suggests that Gleichenia species with sori in laminar pits were more widespread than previously thought. The presence of Gleichenia in this deposit indicates open and disturbed habitats in the region.