Helminths Infecting Sympatric Congeneric Treefrogs in Northeastern Brazil

We aimed to describe the helminth fauna associated with two sympatric congeneric treefrogs species (Boana multifasciata and Boana raniceps) from a highland marsh in northeastern Brazil. In addition, we investigate the body size influence on parasitological descriptors in these treefrogs, in which we expected that larger frogs would have greater abundance and richness helminths too, and no differences with respect to helminth composition once both hosts are exposed to similar environmental conditions.

We collected anurans during the rainy season from 11 January to 09 February 2019, using visual and auditory searches in breeding environments. We analysed the presence of ectoparasites under an epidermis, oral cavity, and endoparasites present in the organs. Using a Linear mixed-effects model we tested the relationship between the host body size (length and weight) and helminths abundance and richness. In addition, we used the ANOSIM R test to investigate the differences between the hosts with respect to helminth composition.

We recorded 37 individuals (15 specimens of B. multifasciata and 22 of B. raniceps), in which 89.1% of them were infected by at least one helminth species. We found 355 helminths from 12 taxa parasitizing the two treefrogs, but just three parasite taxa were common to both species. All identified helminth species found in B. multifasciata are new records and four are new records for B. raniceps. In addition, we present the first record of Cosmocerca paraguayensis in Brazil. We found no support for the hypothesis that larger frogs tend to be more parasitized, at least for congeneric species, and sympatric hosts species have similar helminth composition. We also present a compilation of helminths occurring in treefrogs belonging to the Boana genus in South American, increasing our knowledge of the parasitic diversity of Neotropical anurans.

Our results suggest a lack of knowledge about helminth fauna associated with amphibians even for common and widely distributed species, such as Boana spp., and demonstrate the need to deepen our knowledge about host parasitic relationships, especially in the Neotropical region.