Canningia spinidentis gen. et sp. n. infects the fir bark beetle Pityokteines spinidens Rtt. in Austria. The pathogen attacks mainly the fat body, Malpighian tubules, the muscles and the connective tissue of larvae and adults, and the gonads of adults. The development is haplokaryotic, with single spores. Spores are short tubular, uninucleate, with globular anchoring disc inserted subapically, laterally, in a depression of the endospore wall. Polar filament is isofilar, with 5/6 coils. Polaroplast is composed of two lamellar parts of different density. A new genus Canningia gen. n. is proposed based on differences in ultrastmc-tures of spores from Unikaryon Canning, Barker, Hammond et Nicholas, 1974.