The aim of the present study was to provide a current survey of the species of parasites found in the Upper Paraná River floodplain, as well as to investigate which strategies and mechanisms used by parasites, are favored and which environmental factors influence the parasite community in the studied environments. During a seven-year period from February 2000 to September 2007, 3,768 fish belonging to 72 species were collected and analyzed for the purpose of studying the parasite fauna. A total of 337 species of parasites were reported, including 12 new descriptions: one myxosporid, Henneguya paranaensis Eiras, Pavanelli and Takemoto Keywords: ichthyoparasites, biodiversity, helminthes, crustaceans, parasite ecology. Diversidade dos parasitos de peixes da planície de inundação do Alto Rio Paraná, BrasilResumo O objetivo do presente trabalho foi realizar um novo levantamento das espécies de parasitos encontradas na planície de inundação do Alto Rio Paraná, bem como investigar quais estratégias e mecanismos utilizados pelos parasitos são mais favorecidos e quais fatores ambientais estão influenciando a comunidade parasitária nos ambientes estudados.

Materials and MethodsThe list of parasitic crustaceans of fishes in Brazil was based on extensive search of published records. This bibliographic review of the crustacean species reported from fishes in Brazilian waters was complemented with information from the Zoological Record, Biological Abstracts, Web of Knowledge, Google Scholar, Aquatic Sciences and Fisheries Abstracts, Biological and Agricultural Index Plus and the Scopus. Data were compiled until March, 2013. In the case of parasitic copepods, only information not presented in the checklist of Copepoda parasites of fishes from Brazil by Luque and Tavares (2007) was included. The number of parasitic associations was calculated from the sum of the richness of species of parasites on each host species.The checklist follows the classification and systematic arrangement proposed by Boxshall and Halsey (2004) for Copepoda, and Young (1998) and Martin and Davis (2001) for other crustacean groups.The species of crustaceans are arranged according to taxonomic categories, within which the species are presented in alphabetical order, followed by hosts (specific name), site of infection, habitat, localities and references (between parentheses, in chronological order). In addition, the checklist also includes crustacean species identified only at the genus level and undetermined species. Crustacean names presented in the checklist follow the most recent taxonomic literature, but validity of individual taxa or reliability of their records was not critically examined by the present authors. Host species were arranged in taxonomic and then alphabetical order.The key to identification of the genera of parasitic crustaceans from fishes in Brazil has been produced on the basis of those by Delaney

Diplostomum (Austrodiplostomum) compactum (Lutz, 1928) metacercariae (Platyhelminthes, Digenea) were found in six fish species, belonging to two orders (Characiformes and Perciformes) and three families (Erythrinidae, Sciaenidae and Cichlidae). A total of 477 individuals were collected, from August 1999 to May 2001, in the upper Paraná River floodplain, Brazil. The metacercariae were infecting the eyes of six host species and the brain of five of them. Plagioscion squamosissimus, Satanoperca pappaterra and Cichla monoculus presented the highest values of prevalence, mean intensity and mean abundance. Diplostomum (A.) compactum was over-dispersed in the population of Hoplias aff. malabaricus, S. pappaterra, P. squamosissimus, Crenicichla britskii and C. monoculus. No significant difference was observed in the metacercariae distribution in the right and left eyes. The abundance of D. (A.) compactum metacercariae was positively correlated with the host's relative condition factor in H. aff. malabaricus and S. pappaterra. No significant difference of the abundance of parasitism between the sex of the hosts was evidenced. In relation to the prevalence, significant difference was observed only in C. britskii. Positive correlations were verified between the prevalence of infection and the standard length of the specimens in C. britskii and the intensity of infection and the standard length of the hosts in P. squamosissimus and C. monoculus. In relation to parasite abundance and the standard length class of the host, significant differences were observed in P. squamosissimus, C. britskii and C. monoculus.

Parasites of 136 specimens of Hemisorubim platyrhynchos, popularly called jurupoca, were analyzed. Fourteen parasite species were recorded: four digeneans (Crocodilicola pseudostoma, one Gorgoderidae species, Sanguinicola platyrhynchi, and Sphincterodiplostomum sp.); three cestodes (Goezeella paranaensis, Spatulifer maringaensis, and Mariauxiella piscatorum); five nematodes (Contracaecum Type 1 larvae of Moravec, Kohn, & Fernandes, 1993; Contracaecum Type 2 larvae of Moravec, Kohn, & Fernandes, 1993; Cucullanus (Cucullanus) zungaro; Eustrongylides ignotus; and Goezia sp.); one acanthocephalan (Quadrigyrus machadoi), and one pentastomid (Sebekia sp.). Most of the helminth specimens were found in larval stages, confirming that H. platyrhynchos is a significant source of their transmission. No dominance was reported. With the exception of Contracaecum Type 2 (featuring random dispersion), the species had a clumped pattern of dispersion in the host sample. Evidence of competition among parasite species was not reported. Several species of parasites were correlated with host size and sex. This fact may be explained by increase in food content and possible behavioral modifications of male and female hosts. Infracommunity diversity was not related to host size or sex.

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