On the relation of Potamomyces armatisporus to the fossil form-type Mediaverrunites and its taxonomical and ecological implications

This study links the spores of the recent ascomycete genus Potamomyces with the fossil form-taxa Mediaverrunites. Spores of the only known representative of Potamomyces, P. armatisporus, were found in recent material from Nepal together with a previously unknown spore type described here for the first time as Potamomyces nepalensis-type. Potamomyces is thus not a monotypic genus. The rarely isolated type species P. armatisporus is known as a lignicolous freshwater ascomycete from tropical rivers. Our findings indicate that the genus also lives in damp conditions in terrestrial habitats, and is recently distributed also in subtropical regions. Based on the fossil findings of Mediaverrunites, the genus Potamomyces evolved at least 25 million yr ago at the onset of younger Tertiary. Potamomyces is an excellent example of the potential of interdisciplinary fungal research, combining insights from fungal evolution, taxonomy, ancient and recent distribution and ecology.