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Using information from all published reports and data collected during several parasitological surveys between April 2003 and September 2009, a checklist of the parasites of fishes from Guandu River, southeastern of Brazil was generated. A total of 85 parasite species, 54 named species (1 Acanthocephala, 1 Cestoda, 2 Crustacea, 13 Digenea, 11 Nematoda, 23 Monogenea and 3 Myxozoa) and 31 undetermined species (3 Acanthocephala, 2 Cestoda, 1 Crustacea, 8 Digenea, 8 Nematoda, 4 Hirudinea, 3 Monogenea and 2 Myxozoa) in 21 fish host species from Guandu River, were listed in the current study, including 36 new locality records and 36 new host records. Also, a host-parasite list is included herein.

Pollution in aquatic ecosystems due to negative human activities remains a problem in both freshwater and marine environments and is an ongoing subject of research. Several studies have shown that some fish parasites can be used as a tool for biomonitoring because they demonstrate higher metal accumulation capacity compared to their host tissues. However, compared to acanthocephalans, information regarding the absorption mechanisms and accumulation rates in nematodes is relatively limited. Here, we evaluated the potential of larvae Contracaecum sp. (L3) as indicators of contamination by metals by analyzing thirteen element concentrations: magnesium (Mg), aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), cadmium (Cd), barium (Ba), and lead (Pb) in the parasites and host Acestrorhynchus lacustris, using inductively coupled plasma mass spectrometry. Twelve of the thirteen analyzed elements were detected in at least 2-fold higher concentrations (e.g. Ni) and were up to approximately 50-fold higher (e.g. Pb) in parasites than in host tissues, including elements known for their high toxicity (As, Cd, Pb) and those considered to be essential (Cu and Zn). Our results suggest that Contracaecum sp. larvae can be used as bioindicators of metal contamination because even in early stages of development, numerous essential and non-essential elements were accumulated, making this system a useful tool for monitoring polluted environments.

Four species of Ligophorus (Monogenea: Dactylogyridae), i.e., L. tainhae n. sp., L. brasiliensis n. sp., L. guanduensis n. sp., and L. lizae n. sp., are described. The specimens were collected from the gills of Mugil liza (Mugilidae) from the Guandu River (22 degrees 48'32"S, 43 degrees 37'35"W), State of Rio de Janeiro, Brazil, between January 2008 and March 2008. The male copulatory organ of L. tainhae n. sp. differs from the all known species of this genus in having the largest accessory piece, the length of accessory piece exceeding the length of the copulatory organ tube, and the distal tip of the lower lobe crossing the upper lobe. Ligophorus brasiliensis n. sp. and L. guanduensis n. sp. have a similar shape of the accessory piece, but in L. guanduensis n. sp. the lower lobe is larger than the upper lobe (as opposed to L. brasiliensis n. sp.), the ratio between length of upper lobe and the length of the proximal part of the accessory piece before the bifurcation is shorter and the distal tip of the lower lobe extends to the level of the upper lobe (in L. brasiliensis n. sp. the distal tip of lower lobe crossing the upper lobe). In L. lizae n. sp., the terminal bifurcations of the accessory piece are equal in length and unequal in the other 3 new species. Species of Ligophorus are recorded for the first time from Brazil.

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Sixty specimens of singing catfish Trachelyopterus striatulus (Steindachner, 1877) (Siluriformes: Auchenipteridae) collected from Guandu River (22° 48' 32" S and 43° 37' 35" W), in the state of Rio de Janeiro, Brazil from October 2006 to March 2009, were necropsied to study their parasites. From the 60 specimens of T. striatulus examined 57 were parasitised by at least one parasite species. The majority of the parasite specimens collected were monogeneans followed by Nematoda, Digenea and Hirudinea. Cosmetocleithrum sp. was the numerically predominant species with highest prevalence and abundance. The parasites of T. striatulus showed the typical pattern of aggregated distribution. No parasite species showed significant correlation between the body total length of the host and their abundance. The mean parasite species richness was not correlated with the host's total body length and sex. Values of the Brillouin index of diversity had a mean of H = 0.083 ± 0.136.Keywords: parasite ecology, fish parasites, Trachelyopterus striatulus, Guandu River, Brazil. Ectoparasitos como espécies numericamente dominantes na comunidade parasitária deTrachelyopterus striatulus (Siluriformes: Auchenipteridae) do rio Guandu, Sudeste do Brasil ResumoEntre outubro de 2006 a março de 2009 foram necropsiados 60 espécimes de cumbaca, Trachelyopterus striatulus (Steindachner, 1877) (Siluriformes: Auchenipteridae) provenientes do rio Guandu (22° 48' 32" S e 43° 37' 35" O), estado do Rio de Janeiro, Brasil para estudo de suas comunidades parasitárias. Dos 60 espécimes de peixes examinados, 57 estavam parasitados por pelo menos uma espécie de metazoário parasito. Os monogenéticos constituíram a maioria dos espécimes coletados, seguidos de Nematoda, Digenea e Hirudinea. Cosmetocleithrum sp. foi a espécie numericamente predominante, com maiores valores de prevalência e abundância. Os parasitos de T. striatulus apresentaram um típico padrão de distribuição agregado. Nenhuma espécie de parasito apresentou correlação significativa entre o comprimento total do hospedeiro e sua abundância. A avaliação do efeito do sexo do hospedeiro na abundância parasitária não apresentou resultados significativos. A riqueza de espécies de parasitos não apresentou correlação com o comprimento total e sexo dos hospedeiros. As infracomunidades parasitárias tiveram uma média para o índice de diversidade de Brillouin de H = 0.083 ± 0.136.Palavras-chave: ecologia parasitária, fish parasites, Trachelyopterus striatulus, rio Guandu, Brasil.

In the present paper, we described the first record of an epibiont protozoan Epistylis sp. Ehrenberg, 1830 (Ciliophora, Peritrichia)

An occurrence of the copepod Lamproglena monodi Capart, 1944, parasitizing freshwater fishes in Brazil is presented, along with new morphological data. This crustacean was originally described parasitizing several cichlids in Africa. In the present study, the crustaceans were collected from the body surface and gills of two fish species native to Brazil [Astronotus ocellatus (Agassiz, 1831)