ABSTRACT
The microhabitat and surface topography of microcotylid monogenean parasites Neothoracocotyle commersoni and Pricea multae from gills of Spanish mackerels, Scomberomorus commerson was investigated. The results showed that N. commersoni was aggregated at the first gill sector while P. multae was aggregated at both first and second sectors in single infestation. In contrary, in mixed infestation, N. commersoni occupied the first sector of gills and P. multae was restricted only at the fourth sector with high intensity of infestation compared to N. commersoni. Aggregation of single species of monogenea in restricted habitat may aid cross-fertilization and hence producing of hybrids strains of parasites which might be more potent and vicious causing severe damage to the host. Surface ultrastructure of the representative monogenea showed that the tegument was provided with microvillus-like projections that suggested metabolic exchange and absorption of micromolecular nutrients from the surrounding environment. The architecture of clamps of N. commersoni was differed from that of P. multae in possessing microvillous-like projections which may act as organ of nutrition beside its principle attachment function. Ultrastructure of the clamps of both species described aid in understanding of the parasite habitat and survival.
