The fauna of Mongolian bats and their ectoparasites is not yet fully documented. This study analyzes ectoparasite samples of 15 bat species from diverse taiga, steppe, and desert locations. We recorded 27 parasite species in total and report their abundance, host preference, and occurrence herein. In describing a new bat fly species (Basilia dolchii n. spec.), reporting six parasite species never before recorded in Mongolia, and examining rare host species such as Myotis frater and Murina hilgendorfi, this work expands present knowledge in this research area. To assess respective individual and species-specific parasite loads comprised of different insects or mites, we introduce a parasite body size dependent model
