Structure of the Tegument and Ectocommensal microorganisms of Gyliauchen nahaensis (Digenea : Gyliauchenidae), an inhabitant of herbivorous fish of the Great Barrier Reef, Australia

The ultrastructure of the tegument and tegument-associated microorganisms o f the gyliauchenid digenean Gyliauchen nahaensis is described by transmissi on and scanning electron microscopy. The tegument is devoid of surface spin es and is characterized by a moderately folded apical membrane, abundant ve sicles, basal mitochondria, a folded basal plasma membrane, and a thick bas al matrix. Microorganisms form a dense biofilm on the tegument of the poste rodorsal surface and the excretory papilla. At least 7 microbial morphotype s were identified, including eubacteria, spirochaetes, and nanobacteria.