Preliminary insights into genetic diversity and history of Nuphar lutea and N. pumila (Nymphaeaceae) in isolated southwestern European populations

•We investigate genetic variability of isolated populations of Nuphar lutea and N. pumila.•We sequenced nuclear ribosomal ITS and chloroplast intergenic spacers.•No evidence for southwestern European long-term refugium for Nuphar species.•Nuphar pumila and N. lutea spread from the Far East to Europe.•No signs of hybridization among Nuphar lutea and N. pumila were found.