New records of helminths in Chelidae freshwater turtles (Testudines) in South America

Helminthological studies with Chelidae freshwater turtles in South America were conducted in Argentina, Uruguay and Brazil, where nematodes, digeneans and monogeneans were reported. In this context, the study aims to report new cases of gastrointestinal helminth parasites of Acanthochelys spixii, Hydromedusa tectifera, and Phrynops hilarii. A total of 65 hosts from the southern region of Rio Grande do Sul, Brazil, were examined. Seven taxa belonging to Nematoda, Digenea, and Monogenoidea have new cases on hosts Chelidae in South America, as well as a Nematoda and two Digenea have new host cases for Brazil. Thus, the study expands the knowledge about the diversity of helminths and the geographic distribution of taxa associated with Chelidae turtles.


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The parasites are important in the conservation of biological resources and ecosystems, as well as acting as bioindicators, are important pieces in studies of environmental impact or even conservation of host species, due to the close host-parasite interaction (Marcogliese, 2004). However, parasitological studies are often neglected, being regarded when somehow the parasites cause diseases in their hosts or degrade biological products, causing economic damages (Marcogliese, 2004;Amato & Amato 2010).

Caimanicola brauni
Most gastrointestinal helminths can be acquired through the ingestion of intermediate and/or paratenic hosts, which transmit the infective forms through the trophic chain (Dobson et al., 2005).
Although there is little knowledge about the life cycle of helminths found parasitizing the freshwater turtles studied in this research, it is possible to affirm that most present heteroxenic life cycle, based on studies of similar species or species of the same family. Spiroxys contortus and representatives of Camallanidae use crustaceans as intermediate hosts (Hedrick, 1935;Anderson, 2000). Dioctophyme renale, a helminth recognized by its zoonotic potential, commonly parasitizes the kidney of domestic and wild mammals, with oligochaetes as intermediate hosts and fish and amphibians as paratenic hosts (Anderson, 2000). Some species of Physaloptera use beetles, cockroaches, and crickets as intermediate hosts (Anderson, 2000). Molluscs, fish, and anurans act as intermediate hosts of digeneans belonging to Cryptogonimidae (Cribb et al., 2003;Miller & Cribb, 2008). The host species of the present study were considered generalist and/or opportunistic, with the diet composed of invertebrates (Insecta, Gastropoda, Crustacea, Hirudinea, Arachnida, Malacostraca, and Oligochaeta), anurans, fish and plant fragments (Huckembeck et al., 2007;Bonino et al., 2009;Alcade et al., 2010;Brasil et al., 2011;Assman et al., 2013). In this context, helminth infections may be related to the diet of the freshwater turtles, since these infections may be influenced by the habitat and eating habits of their hosts (Ferguson & Smales, 2006).
According to Mascarenhas et al. (2016) road-killed animals can offer interesting results for helminthological research as observed for freshwater turtles, providing important information about the diversity of their parasites, and about the biology of the hosts, that may contribute to the conservation Rev. Bras. Zoociências| 21(1) | 2020 7 of the involved species and their habitats. Most of the helminthological studies related to Chelidae freshwater turtles in the Southern area of Brazil were performed with animals collected on roads and highways, demonstrating the importance of the use of this type of material in helminthological research.
The diversity of helminth parasites of A. spixii, for example, was unknown until 2013 when the first studies using animals found dead on roads in the south of Brazil began to reveal digenetic and nematodes helminths parasitizing the species (Mascarenhas et al., 2013(Mascarenhas et al., , 2016.