Host-parasite interaction between trematode, Clinostomum marginatum (Clinostomidae) and armoured catfish, Pterygoplichthys pardalis (Loricariidae) from Brazilian Amazon.

Clinostomid trematodes are only widely studied due to the ability to infect their metacercariae, which can affect amphibians, fish, snakes and occasionally mammals, with occasional records in humans. The Loricariids constitute the most diverse family of neotropical fish, with more than 800 registered species. They present a large heterogeneity of colors and body forms that reflect its high degree of ecological specialization and importance on economic aspects such as ornamentation and food. In spite of these factors, studies involving the diversity of parasitic fauna that affect in these fish is still scarce. In this aspect, our study presents the first record of occurrence of the parasite Clinostomum marginatum in association with the Loricariid Pterygoplichthys pardalis in the Amazon region of Brazil. In September 2018, in the river mouth of Tapajós river, tributary of Amazon river, 32 specimens of P. pardalis and six specimens of Aphanotorulus emarginatus were captured. The parasitological studies revealed the occurrence of metacercariae of C. marginatum in association with P. pardalis, representing a prevalence of 12.5% with a mean abundance of 0.18 and a medium intensity of infection of 1.5. No C. marginatum parasitism was observed in A. emarginatus.