Helminths of Steindachnerina insculpta in two distinct stretches of the Taquari River, state of São Paulo, Brazil.

The purpose of this study was to evaluate the helminth fauna of Steindachnerina insculpta in the Taquari River, a tributary of the Jurumirim reservoir in the state of São Paulo, and to investigate whether some helminth species may act as a bioindicator of environmental impact. The host fish sample was composed of 60 specimens, with 30 individuals sampled in a lotic stretch and 30 in a lentic stretch. The following were found: the monogeneans Anacanthoroides mizelli, Diaphorocleidus kabatai, Urocleidoides sp. and Euryhaliotrema chaoi; the digenean Sphincterodiplostomum musculosum and unidentified metacercariae; the nematode Travnema travnema and unidentified larvae; and the acanthocephalan Gorytocephalus plecostomorum. The total prevalence of monogeneans (z = 3.14; p = 0.002) and A. mizelli (z = 3.879; p ≤ 0.001), as well as the mean abundance of total monogeneans (U = 642.0; p ≤ 0.001) and A. mizelli (U = 623.5; p ≤ 0.001), were higher in the lentic stretch. Steindachnerina insculpta and its monogeneans comprise a potential group that could be used to investigate environmental impact, as demonstrated in this study.