Similarity between metazoan parasite communities of two sympatric brackish fish species from Brazil.

Between March 2000 and February 2003, 63 specimens of Genidens barbus and 69 specimens of Aspistor luniscutis (Siluriformes: Ariidae), sympatric species from the coastal zone of Angra dos Reis (23 degrees 01'S, 44 degrees 19'W), RJ, Brazil, were necropsied to study their metazoan parasite communities. Parasite community descriptors were calculated and possible similarities statistically tested. Twenty-two species of metazoan parasites were identified, 15 species from G. barbus and 16 associated with A. luniscutis. Nine species were common to both host species; 4 of them exhibited significant differences in terms of abundance and prevalence. Mean total abundance, species richness, diversity, evenness, and Berger-Parker dominance values were not significantly different in the 2 species of fish. Similarity within parasite infracommunities showed highest homogeneity in A. luniscutis. The parasite infracommunities of A. luniscutis and G. barbus were characterized by ectoparasite dominance and scarcity of species with high prevalence. Nevertheless, low values of similarity were observed between infracommunities, and evidence for 2 distinct infracommunities groups was found.