Gastrointestinal helminths associated with three species of freshwater turtles in the Pampa biome, southern Brazil

Maintenance of the life cycle of a wide diversity of helminths depends on the aquatic environment. Freshwater turtles are considered one of the main groups in these ecosystems due to their high density and biomass. However, there is little information on the infection parameters of helminths associated with the Chelidae species Hydromedusa tectifera, Phrynops hilarii, and Acanthochelys spixii that occur in the Pampa biome. Therefore, this study aimed at analyzing the gastrointestinal helminth assemblage of the three species. Analyses showed that A. spixii was associated with 11 helminth taxa while P. hilarii and H. tectifera were parasitized by eight taxa each. The gastrointestinal helminth assemblage of A. spixii and H. tectifera showed high similarity by the Morisita index. Infections suggest that the helminth fauna is directly related to the diet of the hosts, since A. spixii, P. hilarii, and H. tectifera are generalist and/or opportunistic with diets composed of various invertebrates, which, in turn, are part of the life cycles as intermediate hosts of most of the identified helminths. Thus, this study highlights not only the importance of helminthological research for the understanding of the biology of host organisms, but also the need for conservation of flooded areas characteristic of the Pampa biome, which is essential to maintain the diversity of the ecosystem.

Helminth’s assemblage of Trachemys dorbigni (Testudines: Emydidae) in southern Brazil: implications of anthropogenic environments and host’s genders

ABSTRACT The assemblage of helminths of Trachemys dorbigni was analyzed according two environments (rural and urban) and according to host’s gender. Thus, the helminths found were: Spiroxys contortus (Rudolphi, 1819), Falcaustra affinis (Leidy, 1856), Camallanus emydidius Mascarenhas & Müller, 2017, Dioctophyme renale (Goeze, 1782) (larvae), Eustrongylides sp. (larvae) (Nematoda), Telorchis corti (Stunkard, 1915), Telorchis achavali Mañé-Garzón & Holcman-Spector, 1973, Telorchis spp. (Digenea), Polystomoides rohdei Mañé-Garzón & Holcman-Spector,1968 and Neopolystoma sp. (Monogenoidea). Parasitological indices suggests that S. contortus, F. affinis, C. emydidius, T. corti and P. rohdei are species common in helminth assemblage of T. dorbigni in southern Brazil. Infection by Dioctophyme renale is typical of the urban area and suggest relation with eutrophication process and feedback of parasitic cycle in the freshwater urban environment. Parasitological indices of Neopolystoma sp. and T. achavali suggest to be occasional infections; whereas infection by Eustrongylides sp. could be considered accidental. About Telorchiidae, there was no co-occurrence of the species of this group for the examined hosts. In relation to host’s gender, it was observed that infections by S. contortus, F. affinis, C. emydidius and T. corti had higher rates in females, showing a more intimate association with the females of T. dorbigni. The results suggest that human impact on the environment could affect the infrapopulacional dynamics of parasite species influencing the presence and rates of infection of helminths or exacerbating heterogeneities related to host’s gender.

Nematode parasites of Chelidae (Testudines) from southern Brazil

The presence of helminths associated with freshwater turtles is rarely reported. There are no records of nematodes parasitizing Acanthochelys spixii, and for Hydromedusa tectifera, there is only the report of unidentified nematodes found in this species in Argentina. This is the first report of nematodes (Spiroxys contortus and Camallanus sp.) in A. spixii and the first record of Spiroxys contortus and Camallanus sp. in H. tectifera. This is the southernmost record of S . contortus because this nematode was previously recorded only in Mexico.