A Previously Undescribed Stage in the Life Cycle of Harpellales (Trichomycetes)

Abstract

A free-living stage of a species of Harpellales (Trichomycetes) is described associated with Simuliidae (Insecta, Diptera) eggs after oviposition, larval moults and fecal material collected from a stream in Devon, United Kingdom. The most immature stage observed comprised a chlamydospore which later formed two diametrically opposed generative cells. Each generative cell produced a cylindrical, coiled trichospore with up to seven appendages. Owing to the close association of the chlamydospores with Simuliidae and the shape of the trichospore it is speculated that the form described is a stage in the life cycle of a species of Harpeila (Harpellales, Harpellaceae). Similarity between the chlamydospore and an unnamed zoosporic fungus known to be pathogenic to the ovaries of Simuliidae is discussed.