Phylum: Ascomycota Family: Mycosphaerellaceae
Stigmidium ascophylli (Cotton) Aptroot (2006)
A tiny fungus living in the receptacles of Channelled Wrack Pelvetia canaliculata and Egg Wrack Ascophyllum nodosum. These seaweeds live on the upper shore so are less inundated than other brown seaweeds, especially Channelled Wrack. Infrequently recorded but thought to be very common
References:
Webber - Observations on the structure, life history and biology of Mycosphaerella ascophylli