Fossil water lily fruits with seeds Nymphaea subgenus Lotos, from the Oligocene of Armissan/Narbonne (France)

摘要

Based on specimens from a historical collection from the classical Oligocene locality Armissan (Southern France) fossil fruits of Nymphaeaceae are described that can be affiliated to the Nymphaeaceae genus Nymphaea subgenus Lotos with confidence. Such findings were first described in 1865 by Saporta from Armissan as an extinct genus, Anoectomeria. However, in the absence of preserved seeds, and due to a misinterpretation of the organisation of the fruits, the fossils could only be affiliated to Nymphaeaceae in general. The identification of the historical specimens with preserved seeds allows a new interpretation of such fossils and, hence their identification as fruits of the subgenus Lotos. Especially the characteristical mode of fruit dehiscence, which leads to typical stigmatic discs in extant as well as in fossil specimens, confirms this affiliation. In this study, the flowers/fruits described by Saporta (rhizome, leaves and isolated seeds were also included in his taxa) are revised to Nymphaea (subgenus Lotos) brongniartii. Comparable Paleogene fossils from other localities are also discussed. Based on N. (L.) brongniartii the minimal geological age of the subgenus Lotos can be determined as Late Oligocene. By interpretation of the comparable Paleogene fossils as belonging to subgenus Lotos the minimal geological age of this taxon would even be Middle Eocene. The Late Oligocene minimal geological age of Lotos is in agreement with phylogenetic trees based on molecular data and allows a better calibration of molecular phylogenetic trees of Nymphaeaceae.