Typical intracranial myiasis in Nigerian red river hogs (Potamochoerus porcus) caused by an unknown bot fly (Diptera: Oestridae)

We report an unknown taxon of bot fly (Diptera: Oestridae: Oestrinae) in red river hogs (Potamochoerus porcus Linnaeus, 1758) in Cross River State, Nigeria. From direct observation and interviews with local hunters, we document that, remarkably, the parasite typically occurs within the intracranial supra-meningeal space – i.e., between the inner wall of the skull and the brain – but without causing visible inflammation or clinical signs. The parasite is most similar (up to 87.9%) to Rhinoestrus usbekistanicus based on cytochrome oxidase subunit 1 DNA sequencing but is sufficiently divergent phylogenetically to represent a new or previously un-sequenced taxon. Morphologically, the parasite shares some, but not all, features with R. nivarleti. Local cultural belief systems attribute aspects of red river hog behavior (e.g. intelligence, elusiveness) to the parasite, suggesting a prolonged presence in the red river hog population. The parasite's unusual anatomic location may be aberrant, or it may be a protective adaptation to life in red river hogs, which forage vigorously with their snouts.