Diversity, host specificity, speciation and ecological equivalence in some dactylogyrid monogenoideans of freshwater fish.

Abstract: Objective: To observe their specificity, speciation and ecological equivalence by using previous and present records, from freshwater fish from Tanakpur to Sultanpur areas, during 2009 & 2010. Methods: Data is gathered from the published records to compare it with the present records and entered into a computer database. The taxonomy of monogenoideans follows and those of fish follows. The worms were gently scrapped from the gills of fish and counted manually. They were studied mostly live, under a phase contrast microscope (Olympus CX 41 U-DA 4E 03365 Japan) or fixed in 3% formalin, after being relaxed in lukewarm water. Results: These monogenoids have perfect ecological equivalence, as their macro habitat is geologically connected. They exhibit specificity at different taxonomic levels of the parasites and the hosts. Sympatric speciation of parasites and their host is evident in the present study. Conclusions: The monogenoidean fauna, in this region, has its species integrity in the past sixty to sixty five years. From this important body of study, it seems likely that host specificity among monogenoids from the fresh water fish is more widely spread than previously thought. Seasonal variations, probable controlling factor of infection, determine the intensity. [Copyright &y& Elsevier]