Helminths of Reindeer (Rangifer tarandus) in the Southern Continental Palearctic

Reindeer in the southern Palearctic remain poorly documented, especially regarding helminths. Limited data exist for their small, isolated, and conservation-important populations. Because helminths affect survival, reproduction, and population stability, and act as biogeographic indicators, knowledge of their diversity in these southern regions is considered essential for research and management purposes. A total of 242 fecal samples were obtained from 2012 to 2025 from reindeer inhabiting China, Kazakhstan, Mongolia, and Russia. These samples were examined by coproscopy. Morphological diagnoses were supplemented with DNA analyses. Trematodes of Paramphistomoidea, cestodes of Moniezia, and nematodes identified as E. rangiferi, O. macrotis, the dimorphic O. gruehneri/O. arctica, as well as Nematodirus, Capillaria, and unidentified small strongylids were revealed. All taxa detected in this study have been reported previously for R. tarandus and for the Palearctic, exception for Nematodirus sp. for the southern area. However, examinations of reindeer from selected regions in Russia, as well as Mongolia and Inner Mongolia (China) were carried out for the first time. Southern range limits were established for E. rangiferi in China and O. macrotis in Russia. Species O. macrotis has been proposed as a biogeographical marker for wild reindeer in the Eastern Siberia, while Capillaria may indicate domestic herds.