Observations on the host specificity of Pomphorhynchus patagonicus (Acanthocephala) from the Alicura Reservoir (Patagonia, Argentina).

The acanthocephalan Pomphorhynchus patagonicus was found in 3 species of fish in the Alicura Reservoir (Patagonia, Argentina). These included Oncorhynchus mykiss, Patagonina hatcheri, and Percichthys trucha. Prevalence, intensity, size of the parasites, and percentage of gravid females were analyzed. The relatively low prevalence and intensity were probably due to the low consumption of the intermediate host, Hyalella patagonica. The highest values of intensity, length, and percentage of gravid females were found in Percichthys trucha. This species is considered to be the preferred host of P. patagonicus in the reservoir. No mature eggs were found in O. mykiss; this, together with the parasite's low growth rate, underlines the hypothesis that this species is not a suitable host for P. patagonicus.