The first record of a simulid gut fungus Simuliomyces microsporus(Harpellales) in Japan using freeze-preserved host insects for dissection

Abstract

　Simuliomyces microsporus (Legeriomycetaceae, Harpellales) was collected from the hindguts of the larvae of Simulium aokii (Simuliidae: Diptera). This is the first report of this species (genus) from Japan. A thick cell wall was produced between each zygospore and zygosporophore, which was remarkably recognized on the surface of the detached zygospores. The apical cell wall was absent in the remaining zygosporophores on thalli. Solitary detachment of zygospores from zygosporophores was observed for the first time in this species. Host insects were immediately dissected after collection (ordinal method) or dissected after preservation in the frozen condition (new method). In defrosted specimens, dissection of the abdomen and derivation of the mid- and hind-gut was easy, and the harpellalean fungus could be observed. Preservation by freezing of host insects appeared to be a suitable method for studying Harpellales.