The surface topography of Eudiplozoon nipponicum (Monogenea) developmental stages parasitizing carp (Cyprinus carpio L.)

Using scanning electron microscopy (SEM), the external morphology of all developmental stages (egg, oncomiracidium, diporpa, just fused juvenile and adult) of the parasite, Eudiplozoon nipponicum (Monogenea, Diplozoidae), from the gills of carp was studied. During the ontogeny, the tegument, tegumentary and sensory structures are subsequently developed. The tegument of free swimming oncomiracidium occurs in two types — the ciliated and non-ciliated with numerous uniciliated sensory structures. An attachment apparatus starts to form during the oncomiracidium stage. Further developmental stages are adapted to the environment of the gills. Tegumentary folds become more apparent later in development and assist to the parasite’s attachment. In connection with its reproductive strategy, the two morphological structures of diporpa (ventral sucker and dorsal papilla) appear to play important role. On the gills, two individuals need to meet and these structures mediate the fusion between two diporpae. The hindbody of adult parasite is highly modified for attachment. The haptor, folds and lobular extensions are most developed. The forebody is flexible and able to interact with host gill tissue via the mouth and associated mouth structures. The process of food intake of the parasite was discussed.