Two syntopic morphotypes of the genus Hypostomus - H. nigromaculatus and H. cf. nigromaculatus (Atlântico Stream, Paraná State) - were compared through the allozyme electrophoresis technique. Twelve enzymatic systems (AAT, ADH, EST, GCDH, G3PDH, GPI, IDH, LDH, MDH, ME, PGM and SOD) were analyzed, attributing the score of 20 loci, with a total of 30 alleles. Six loci were diagnostic (Aat-2, Gcdh-1, Gpi-A, Idh-1, Ldh-A and Mdh-A), indicating the presence of interjacent reproductive isolation. The occurrence of few polymorphic loci acknowledge two morphotypes, with heterozygosity values He = 0.0291 for H. nigromaculatus and He = 0.0346 for H. cf. nigromaculatus. FIS statistics demonstrated fixation of the alleles in the two morphotypes. Genetic identity (I) and distance (D) of Nei (1978) values were I = 0.6515 and D = 0.4285. The data indicate that these two morphotypes from the Atlântico Stream belong to different species.
ABSTRACT. Sixty-two specimens of Iheringichthys labrosus, captured in Rosana, Taquaruçú, Salto Grande and Canoas I reservoirs, located in the Paraná River basin, were necropsied. Fifty specimens were parasited by at least one species (80.65%). Six parasite species were recorded: one species of Dactylogyridae; one species of Apocreadiidae; one species of Proteocephalidea; Procamallanus (Spirocamallanus) pimelodus Pinto, Fábio, Noronha e Rolas, 1974; Quadrigyrus sp.; and Ergasilus sp. Thirty-five specimens of Iheringichthys labrosus were captured in Upper Paraná River floodplain. Thirteen specimens were parasited by at least one species (37.14%). Five parasites species were found: Herpetodiplostomum gymnoti larvae; one species of Proteocephalidea; Procamallanus (Spirocamallanus) pimelodus; Contracaecum sp. Type 1 larvae of Moravec, Kohn and Fernandes, 1993; and Quadrigyrus sp. In both study sites, the prevalence and parasitism abundance were not correlated with hosts standard length. There were significant differences between prevalence and parasites species abundance according to fishes' sex only in upper Paraná floodplain. Moreover, the parasitism abundance did not influence the host condition factor in both sites. Parasites infra communities from the fishes of both sites comparison presented a similarity of 54.54%.
ABSTRACT. One hundred and twenty-four specimens of Corydoras paleatus (Jenyns, 1842) collected from July 2001 to December 2002 in five reservoirs in Paraná state were analyzed. One hundred and ninety-eight Procamallanus (Spirocamallanus) pintoi (Kohn; Fernandes, 1988) were collected, representing a prevalence of 78.23% and a mean intensity of infection of 2.04 parasites by fish. The values of prevalence and mean intensity of infection for P. (S.) pintoi were submitted to statistical tests for the analysis of the host's relation. Data showed that the standard length and host's sex do not influence the parasitism level. Moreover, no significant difference of parasitism among the five analyzed reservoirs was found and the parasitism does not have seasonality. Kohn; Fernandes, 1988), representando uma prevalência de 78,23% e uma intensidade média de 2,04 parasitos por peixe. Os valores de prevalência e intensidade média de infecção para P. (S.) pintoi foram submetidos a testes estatísticos para a análise de sua relação com o hospedeiro, os quais demonstraram que o comprimento padrão e sexo do hospedeiro não interferem no nível de parasitismo. Também foi verificado que não há diferença significativa de parasitismo entre os cinco reservatórios analisados e que não possuem uma sazonalidade.Palavras-chave: Corydoras paleatus, endoparasitos, reservatórios, Paraná.
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