The ultrastructure of three microsporidia from winter moth, Operophtera brumata (L.), and the establishment of a new genus Cystosporogenes n.g. for Pleistophora operophterae (Canning, 1960)

Abstract

The ultrastructure of three species of microsporidia in winter moths, Operophtera brumata (L.), has been used to consolidate taxonomic assessments previously based on light microscopy. The characters formerly used to assign Nosema operophterae Canning, 1960 to a new genus Orthosoma Canning, Wigley & Barker, 1983, namely that the nuclei are isolated and that sporoblasts are separated from ribbon-shaped multinucleate (2, 4, 8 or rarely 12 nuclei) sporonts, were upheld at the ultrastructural level. Development was in contact with the cell cytoplasm but all stages, which must have included meronts, had an electron dense surface coat. Nosema wistmansi Canning, Wigley & Barker, 1983, was found to be ultrastructurally typical of the genus Nosema Naegeli, 1857. An unusual feature of this species was the close association of cysternae of host endoplasmic reticulum with the surface of meronts, an association lost in sporogony.