Nearctic–Palaearctic relationships of black flies (Diptera: Simuliidae): chromosomal and morphological evidence for the Prosimulium magnum species group in Japan

The banding patterns of the polytene chromosomes of Prosimulium yezoense Shiraki from Japan are resolved relative to the standard map for the genus Prosimulium, revealing two unique fixed inversions and novel autosomal and sex-linked rearrangements. Diagnostic chromosomal and morphological criteria demonstrate that P. yezoense is a member of the Prosimulium magnum group. The species is transferred, with three additional species – P. apoina Ono, P. karibaense Ono, and P. sarurense Ono – from the Prosimulium hirtipes group to the P. magnum group, representing the first geographic record of the group outside North America. The P. magnum group is one of only a few insect taxa, and one of only two simuliid taxa, distributed exclusively in Japan and the Nearctic region.