Elachista scutulata (Smith) Areschoug
Description: Thallus a loose, globose cushion to 30 mm wide from which a tuft of free assimilatory filaments arises. Assimilatory filaments unbranched, usually more than 100 µm wide and 5-10 mm long, coalescing basally together with paraphysis-like filaments into a loose cushion; cortex and medulla present in the cushion. Many discoid chloroplasts in each cell. Unilocular sporangia sunken in the cushion; plurilocular sporangia unknown.
Habitat: mid to lower intertidal; epiphytic on Himanthalia elongata. Widely distributed in Ireland and Britain; western and southern coasts where the host occurs.