Hemoparasites of the Four-Eyed Frog (Pleurodema thaul) from Chile

Amphibians host a diverse array of macro and microparasites, and these relationships can provide relevant information for assessing and monitoring population and ecosystem health. The dynamics and outcomes of these host-parasite interactions are influenced by several biotic and abiotic factors, as well as by the characteristics of both the parasite and the host. This study aims to identify hemoparasites in Pleurodema thaul (four-eyed frog) (Leptodactylidae) across its extensive distribution in Chile and to explore potential relationships between parasite occurrence, host traits, and habitat variables. To achieve this, we surveyed P. thaul populations from 40 localities between the extreme north and south of Chile (22-43°S), in a latitudinal gradient of 2500 km. In each locality, individuals were actively searched along the margin of water bodies, manually captured, sexed, and measured using standard morphometric and biosecurity protocols. Blood samples were collected via facial vein puncture using needles and heparinized capillary tubes. Smears were prepared on-site, fixed with methanol, and stained with 10% Giemsa for subsequent microscopic analysis at 40× and 100× magnification. Hemoparasites were detected in 61% (221/363) of individuals, with three genera identified: the hemogregarines Hepatozoon sp. and Dactylosoma sp. (Adeleorina), with a prevalence of 7% and 39%, respectively, and the hemococcidium Lankesterella sp. (Eimeriorina), with 22%. The study describes the key characteristics of these parasites in both intra- and extracellular developmental stages. These findings contribute to the understanding of anuran hemoparasites by expanding knowledge on their distribution, morphological traits, and local and regional host-parasite interactions.