Aquatic macrophytes from the upper Oligocene fossillagerstätte of Rott (Rhineland, Germany). Part II: A new fossil leaf species of Nymphaea (subgenus Lotos), N. elisabethae Gee et David W. Taylor sp. nov.

Although biologically diverse in insects and plants, the late Oligocene lake deposit of Rott near Bonn in western Germany has yielded very few aquatic macrophytes. Thus, newly discovered evidence of water lilies prompted a phylogenetic analysis of the fossil leaves, whereby one type of water lily leaf was found to pertain to the order Nymphaeales, family Nymphaeceae, genus Nymphaea, subgenus Lotos. Here we describe this previously unknown water lily leaf as a new species of Nymphaea, N. elisabethae Gee et David W. Taylor sp. nov. This leaf is characterized by a notophyllous size, ovate shape, entire margin, narrow basal sinus, and eccentric peltate petiolar insertion. Its primary vein category is actinodromous, while the vein category of lateral primaries and secondary veins off the medial primary vein is brochidodromous. Furthermore, the secondary veins off the medial primary are uniformly spaced, while the tertiary vein course is convex. Comparisons with other leaves from the Rott fossillagerstätte, as well as from other Paleogene and Neogene deposits with water lily leaves in Europe confirm the distinctive leaf morphology of the new species. The occurrence of N. elisabethae representing the subgenus Lotos in the upper Oligocene flora of Rott agrees well with recently discovered carpofloral evidence of the subgenus from the upper Oligocene of southern France. These two fossil occurrences of subgenus Lotos in Europe suggest a time of divergence of about 10 million years earlier than the mid-Miocene divergence time suggested by molecular data.