MONOGENEAN HOST-SPECIFICITY AS A BIOLOGICAL AND TAXONOMIC INDICATOR FOR FISH

The biological significance of host specificity among Monogenea parasi tizing freshwater fish and their use as biological markers are discuss ed. The marking of,host species by strictly host-specific Monogenea is dealt with first; the limits of this taxonomic marking are discussed, particularly in cases when parasite specificity is not entirely stric t. The significance of biological marking by these parasites is then l ooked at from the evolutionary viewpoint - microevolutionary in the ca se of host hybridization, and macroevolutionary for the indication of phylogenetic relationships through host-parasite coevolution. The poss ibility of using the Monogenea of endemic north Mediterranean freshwat er fish as ecological and biogeographical indicators is raised.