Revisiting the isolation source after half a century: on a yellow-green alga.

Fungi-algae interactions, such as lichen-forming fungi and parasitic chytrids on phytoplankton, are common in ecosystems. In contrast, interactions between filamentous fungi and soil algae that can be observed with the naked eye have been given little attention and remain unexplored. Here, we report a fungus that was associated with a visible symptom of dead algae on a soil surface in Sugadaira-kogen, Nagano, central Japan. -like conidiophores were growing on vesicles and dead bodies of a yellow-green alga, . The fungus was identified as based on its morphology by microscopic observation, phylogenetic analysis, and the similarity of the isolation substrate with the first description of the species. Co-culture experiments showed a filamentous cell differentiation of the alga by the fungus, but no harmful or beneficial effects on algal growth. Therefore, we speculate that is a facultative parasite of under natural conditions.