Ephemeropteran fauna of the Koshiki Islands

Abstract

The Koshiki Islands are located in the western part of Kyushu District, and consist of Kami-Koshiki Island, Naka-Koshiki Island, and Shimo-Koshiki Island. Although it is considered that the Koshiki Islands were connected to Kyushu Island during the last glacial period when the sea level lowered, some endemic species have been reported there. This is suggested that the Koshiki Islands have formed their own unique biota. There are few studies of the aquatic insects of the Koshiki Islands. In particular, there are no reports of the distribution of the mayflies that we focus in this study. However, we were able to collect mayflies in some streams of the Koshiki Islands, so we would like to report on them here. We were able to collect at least nine species of six genera, and four families (i.e, Baetidae, Ephemeridae, Heptageniidae, and Dipteromimidae). All the mayfly species recorded on the Koshiki Islands were also recorded on Kyushu Island, and there was no difference in the fauna present between Kami-Koshiki Island and Shimo-Koshiki Island. In Naka-Koshiki Island, we were not able to observe any mayflies. This paper is the first record of mayflies in the Koshiki Islands.