Gastrointestinal parasite diversity in two contrasting guanaco (Lama guanicoe) populations of Argentina: Comparing Chacoan and Patagonian populations.

The guanaco (Lama guanicoe), the largest wild artiodactyl in South America, shows contrasting population trends across its distribution. While more than two million individuals persist in continental Patagonia, only two relict populations remain in the Gran Chaco region. Although gastrointestinal parasites have been documented in some guanaco populations, substantial knowledge gaps persist across their range. This study characterizes the diversity and composition of gastrointestinal parasites in two contrasting populations, one critically endangered and isolated in the Chaco region (Córdoba Province) and another abundant and expanding in southern Patagonia (Santa Cruz Province). Using three coproparasitological techniques and molecular analyses, we observed lower parasite richness in the Chacoan population, with only a few coccidian oocysts detected. In contrast, the Patagonian population exhibited a more diverse assemblage of parasites, including taxa from the phyla Apicomplexa and Nematoda. Molecular analyses supported the detection of Cystoisospora sp. in the analysed samples. These differences provide a basis for further investigation into the ecological and environmental factors associated with parasite assemblages. Overall, our findings highlight the value of continued parasitological monitoring to improve understanding of host-parasite dynamics and their relevance for the conservation of wild camelids under changing environmental conditions.