Two species of Harpellales from Chironomidae (Diptera) newly recorded in Japan

Abstract

Two species in Harpellales, Stachylina subgrandis and Smittium aggregatum were recorded for the first time in Japan. Stachylina subgrandis was identified in the midgut, and Sm. aggregatum was identified in the hindgut of Tanytarsini (Chironomidae) larvae. Three of the four larvae examined had dual infections with these species at each part of the gut. Smittium aggregatum has a well-developed holdfast, consisting of long obovoid cells arranged side by side surrounded by a substance for adhering to the gut lumen. The development process of the holdfast cell arrangement was observed and illustrated here.