Louse flies (Hippoboscidae) are ectoparasitic dipterans found on the body of birds and mammals. They have been reported from a wide geographic range, and eight species from four genera have been recorded from the Nansei Islands, a stretch of islands lying between Southwestern Japan and Taiwan. However, due to difficulties in obtaining samples, we are yet to have a complete understanding of the fauna and our knowledge on their distribution remains limited. Here, we collected louse fly samples from two scops owl species (Otus elegans and O. semitorques) from three islands within the Nansei Islands, and identified them based on their morphological characteristics. Three species, Ornithoica exilis, Ornithomya avicularia and Icosta amamiensis, were reported with different appearance of species on each island. This is the first record of Om. avicularia for Okinawajima, and the first record of this family for Haterumajima (Oc. exilis and Om. avicularia) and Minami-Daitojima (Om. avicularia). We also sequenced mitochondrial COI gene to estimate their phylogenetic positions, and also to understand the inter-insular population structure of Oc. exilis and Om. avicularia, which were collected from multiple islands. We found no inter-insular genetic differentiation between the populations, despite the host owls having low dispersal ability, indicating low host specificity and host switch of these species. We provide a complete list of all 422 specimens examined and identified in this study, along with records of phoresy by mites and chewing lice. We also present an updated key to bird-parasitising Hippoboscidae species reported from the Nansei Islands and unreported potential species.
Ryukyu Islands, Haplotype network, Cox1, Ectoparasite, Biodiversity
