Sphincterodiplostomum musculosum (Digenea, Diplostomidae) infecting Steindachnerina insculpta(Characiformes, Curimatidae) in the Chavantes Reservoir, Southeastern Brazil

Abstract

This study aimed to report the infection by Sphincterodiplostomum musculosum metacercariae in Steindachnerina insculpta from the Chavantes Reservoir, medium Paranapanema River, municipality of Ipaussu, State of São Paulo, Brazil. Thirty specimens of S. insculpta were collected and 29 were infected with S. musculosum metacercariae (prevalence = 96.67%) in the eyes and visceral cavity. The mean intensity of infection and abundance were 96.6 ± 29.41 (7-846) and 93.3 ± 28.6 (0-846), respectively. Positive correlation was observed between parasite abundance in the eyes and standard length (rs = 0.5, p = 0.005), total weight (rs = 0.649, p = 0.0001), and condition factor (rs = 0.439, p = 0.0154). The high parasitism rates by S. musculosum metacercariae in S. insculpta can be an indicative that this fish species is highly susceptible to infection by this diplostomid, and even reflect the presence of a large abundance of the intermediate host. Moreover, S. musculosum metacercariae are reported for the first time in S. insculpta.

Helminths of Steindachnerina insculptain two distinct stretches of the Taquari River, state of São Paulo, Brazil

“…Zago et al (2013) reported lower prevalence (96.67%) for these metacercariae than in the present study. However the mean intensity of infection (96.6 versus 41.5) and mean abundance (93.3 versus 41.5) were higher.…”

“…Thus far, metacercariae of S. musculosum have been found in a few fish species (CESCHINI et al, 2010;TAKEMOTO et al, 2009;ABDALLAH et al, 2005). In the present study, the Berger-Parker index showed that this digenean was the dominant species in S. insculpta, corroborating the findings of Zago et al (2013) and suggesting that this fish species is highly susceptible to infections with this parasite. Moreover, this parasite species was found in the larval stage, suggesting that S. insculpta is in an intermediate position in the food chain and that it might be part of the diet of some piscivorous birds that are the definitive hosts of S. musculosum (ZAGO et al, 2013).…”

“…However the mean intensity of infection (96.6 versus 41.5) and mean abundance (93.3 versus 41.5) were higher. Moreover, Zago et al (2013) found S. musculosum also parasitizing the coelomic cavity. Ceschini et al (2010) found these metacercariae in S. brevipinna, but they were in the ovary of the hosts, with lower prevalence (90.47%) than in the present study, but with higher infection intensity (52.63 versus 41.5).…”

“…A fish parasitized with approximately 40 metacercariae is likely to have cataracts or even blindness, depending on the size of the fish (EVANS et al, 1976apud ZAGO et al, 2013. Thus, high infection rates by these metacercariae in the eyes reinforce this information, since the fish are weakened and become easy prey for the definitive host, thereby allowing this parasite to finish its life cycle (ABDALLAH et al, 2005;ZAGO et al, 2013).…”

Sphincterodiplostomum musculosum (Digenea, Diplostomidae) in Geophagus brasiliensis (Perciformes, Cichlidae) collected in a lake at Dois Córregos, São Paulo, Brazil

“…The posterior portion presents an ovary, a pair of testicles and a subterminal sphincter (SZIDAT, 1969;CESCHINI et al, 2010). This species was described for the first time in Agamia agami (Gmelin, 1789) (Ardeidae) in Brazil, with adult samples in this bird intestine (DUBOIS, 1936 (CESCHINI et al, 2010) and Steindachnerina insculpta Fernández-Yépez, 1948(ZAGO et al, 2013BRANDÃO et al, 2014).…”