Spirogyromyces vermicola is described as a new genus and species inhabiting the gut of free-living nematodes. The spores are ingested and attach to the gut wall of the host. A stout, helicoid, septate hypha grows down the gut and produces one or several helicoid branches. One or more filiform spores arise from the vicinity of each septum and coil around the main axis or its branches. The mature thallus can fill the gut of the nematode with primary (main axis), secondary (branches), and tertiary (spores) coils of striking symmetry. Spores break away from the thallus and are defecated through the anal orifice to the exterior where they are eventually ingested to initiate infection.