Amylostereum is the single genus in the fungal family Amylostereaceae. The genus currently comprises four saprotrophic and parasitic species, which live off living or dead wood. The Amylostereaceae cause white rot in the wood by disintegrating the tissue component lignin. They produce crust-like, partially wavy fruit bodies on the surface of infested trees, which are similar to those produced by Stereum species.

There are four described species in the Amylostereaceae: A. chailletii (the type), A. areolatum, A. ferreum and A. laevigatum. The species were initially considered part of Stereum until mycologist Jacques Boidin found atypical microscopic differences between them. Forty years after his extensive researches from 1958, Boidin reclassified Amylostereum into its own family.

Three Amylostereum species are symbionts of wood wasps in the genera Sirex, Urocerus, and Xoanon, which infest conifers. The female wood wasps deposit their eggs together with fungal spores and mucus in trees, and the fungus is eaten by the wasp's larva as food. The fungus propagates vegetatively through the formation of asexual spores in newly emerged females that are stored in special structures adapted for the transport of symbiotic fungi. The A. areolatum–Sirex noctilio symbiont complex has been studied extensively because of its potential to cause substantial economic losses in the forestry industry, particularly in non-native regions.

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