Fig. 2
DIC light micrographs of Diatomophthora perforans subsp. norvegica at different life cycle stages in Synedra ulna. a, b Clusters of infected diatoms each containing mature parasitoid thallus; c two empty sporangium with column of discharge tubes (red arrow); d colony of S. ulna attached to their red algal substrata with multiple infected diatoms. Scale bars = 50 μm in all pictures