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)

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 sporonts, were upheld at the ultrastructural level. Nosema wistmansi Canning, Wigley & Baker, 1983, was found to be ultrastructurally typical of the genus Nosema Naegeli, 1857. Pleistophora operophterae (Canning, 1960) has been transferred, on ultrastructural criteria, to a new genus Cystosporogenes n.g. Microsporidia which undergo multisporous sporogony in sporophorous vesicles are now distributed among seven genera. These are: Glugea Thelohan, 1891; Pleistophora Gurley, 1893; Pseudopleistophora Sprague, 1977; Vavraia Weiser, 1977; Baculea Loubes & Akbarieh, 1978; Polydispyrenia Canning & Hazard, 1982 and Cystosporogenes n.g. New genera would appear to be needed for Pleistophora sp. of Sandars & Poinar (1976) and PLeistophora sp. of Percy, Wilson & Burke 1982).