Diversity of ectoparasites associated with Rhabdomys pumilio and Rhabdomys intermedius (Muridae) in the Fynbos, Succulent Karoo and Nama-Karoo biomes of South Africa

Rodent species within the southern African genus <i>Rhabdomys</i> are ecologically flexible, exhibit opportunistic behaviour, and are adapted to a wide range of habitat types. They comprise four morphologically cryptic species that are, however, strictly confined to different vegetation types represented by distinct biomes. Descriptive ectoparasite data on the diversity of lice, fleas, mesostigmatic mites, and ticks are currently limited to <i>Rhabdomys pumilio</i> in the Fynbos biome, and narrative data on trombiculid mites are absent. To address these gaps in ectoparasitic knowledge, the present study was extended across a broader geographic scale and included <i>R. pumilio</i> from the Succulent Karoo biome, as well as <i>R. intermedius</i> occurring in the Nama-Karoo biome. The complete ectoparasite assemblage associated with 237 <i>Rhabdomys</i> individuals (171 <i>R. pumilio</i> and 66 <i>R. intermedius</i>) trapped at 12 localities during the spring-summer seasons of 2023 to 2025 yielded more than 10 000 ectoparasite individuals representing five taxonomic groups: lice, fleas, mesostigmatic mites, trombiculid mites, and ticks. Overall, 46 ectoparasitic species were recorded, comprising one louse species, nine flea species, nine mesostigmatic mite species, five tick species, and 22 trombiculid mite species. <i>Rhabdomys pumilio</i> harboured 42 ectoparasite species across the Fynbos and Succulent Karoo biomes, while <i>R. intermedius</i> in the Nama-Karoo biome harboured 21 species. The study provides detailed data on the prevalence, and localization on the host body of 14 chigger species described as new in separate taxonomic papers or awaiting description. Additional contributions include 36 new locality records across ectoparasite taxa, 14 new host associations and 24 mtDNA <i>COI</i> barcodes for flea species, which complement morphological identifications. This study highlights that more extensive geographic sampling of rodent host species can substantially enhance our understanding of the true diversity of rodent ectoparasites in South Africa.