Vairimorpha Pilley 1976

Nuclei diplokaryotic and monokaryotic; life cycle dimorphic, with a dominant diplokaryotic, disporoblastic sequence of merogony and sporogony and a temperature dependent monokaryotic, octosporoblastic sporogony; meiosis probably occurs at the onset of the octosporoblastic sporogony; transmission is per os; disporoblastic sequence all stages are in direct contact with host cell cytoplasm, in merogony diplokaryotic cells divide by binary fission or form short chains of diplokaryotic cells, in sporogony: spindle shaped sporonts, initially with a central diplokaryon, later with two diplokarya situated at the poles, prior to disporoblastic division, produce spores, 5.0 - 6.0 x 2.3 - 2.8 µm, ovoid and have a rugose exospore and thick endospore, with lamellar polaroplast with close-packed anterior lamellae and looser posterior lamellae, polar tube isofilar with about 13 coils, arranged in a single rank obliquely round the diplokaryon; octosporoblastic sequence appears most abudantly when the temperature drops below 25° C, in sporogony diplokaryotic cells become enveloped by a membranous sporophorous vesicle, division into sporoblasts occurs by invagination of the surface in rosette formation, spores, 2.8 - 4.0 x 1.7 - 2.4 µm are ellipsoid and uninucleate, spore wall composed of a smooth membrane-like layer overlying an endospore composed of a thick electron dense layer and a very thick electron lucent layer, polar tube is isofilar with 12 or 13 coils obliquely around the single nucleus; the species causes high mortality in larvae following damage to the intestinal wall by penetration of the polar tubes; type species V. necatrix (Kramer, 1965) Pilley, 1976 in haemolymph and adipose tissue of Pseudaletia unipunctata (Lepidoptera, Noctuidae) and other Lepidoptera. 1976).