Helminth endoparasites of endemic fish Pygocentrus piraya (Characiformes, Serrasalmidae) from Três Marias reservoir, Minas Gerais, Brazil

Abstract

Ten endoparasite species found in Pygocentrus piraya, which is a piranha species native to São Francisco river, were collected from 108 fi sh caught in Três Marias reservoir in 2004 and 2005, namely: Digenea -Austrodiplostomum sp. (metacercariae); Eucestoda -Proteocephalidae gen. sp. (plerocercoids); and Nematoda -Procamallanus (Spirocamallanus) inopinatus, Cystidicoloides fi scheri and Capillostrongyloides sentinosa (adults); Spinitectus rodolphiheringi (juvenile); Hysterothylacium sp., Contracaecum sp. Type 1 , Spiroxys sp. and Goezia sp. (larvae). In helminth fauna, P. (S.) inopinatus has shown higher prevalence and dominance. Fish sex has infl uenced the prevalence of Hysterothylacium sp., which was higher in female specimens. Longer total length of fi sh has positively infl uenced the abundance of C. sentinosa and Hysterothylacium sp.. The rainy season has favored parasitic indices, mainly P. (S.) inopinatus abundance, as well C. sentinosa and Hysterothylacium sp. prevalence and abundance. There were co-occurrences between adult and some larval nematodes. Endemic piranhas, as well as fi nal hosts, are important intermediate and/or paratenic hosts, given the relevant number of larvae (proteocephalideans and nematodes) of heteroxene cycle found in them. Proteocephalidae gen. sp., C. sentinosa, Hysterothylacium sp., Contracaecum sp. Type 1 , Goezia sp. and S. rodolphiheringi are new records parasitizing P. piraya in São Francisco basin.

Characterisation of nematode larvae found in a vulnerable native Australian fish, the southern pygmy perch, Nannoperca australis Günther

“…The present study is the first report of the larval stage of the genus in Australia, which shows the role of a native fish, southern pygmy perch, in its life cycle. According to Santos-Clapp et al (2022), Spiroxys larvae have a higher incidence in smaller fish. Fish may acquire the infection by eating infected first intermediate hosts or paratenic hosts, such as copepods, aquatic insects and molluscs (Moravec 1998).…”

Sebekia sp. (Eupentastomida, Sebekidae) in Pygocentrus piraya (Actinopterygii: Serrasalmidae) from marginal lagoons of the middle São Francisco River basin, Brazil

“…The endoparasitic fauna of P. piraya from the upper São Francisco River, in the Três Marias reservoir, Minas Gerais, was studied by Santos-Clapp et al (2022) and no pentastomid specimens were found. The presence of Sebekia sp., now recorded in P. piraya from the same basin, but originating from marginal lagoons, indicates that the characteristics of these sites favor ingestion of sebekid eggs by piranhas, possibly due to closer contact between these intermediate hosts and crocodilians, i.e.…”