Monetianthus mirusgen. et sp. nov., a Nymphaealean Flower from the Early Cretaceous of Portugal

Monetianthus mirus gen. et sp. nov. is described based on a single coalified flower from the Early Cretaceous (Late Aptian‐Early Albian) Vale de Agua locality, western Portugal. The flower is actinomorphic and probably bisexual, with a perianth of nine or 10 tepals, an androecium of 20 stamens, and a syncarpous gynoecium with a partly inferior ovary of 12 carpels arranged radially around a central column. Phyllotaxis of tepals and stamens is uncertain. Nondestructive synchrotron radiation x‐ray tomographic microscopy of internal structures documents laminar placentation with around six anatropous and ascending ovules in each locule. Comparison of Monetianthus with living plants indicates a clear relationship to extant Nymphaeales in particular with the Barclaya and Nymphaeoideae clade. Monetianthus thus provides evidence of crown group Nymphaeales, and probably crown group Nymphaeaceae, at a very early stage in the initial diversification of flowering plants.