Xerotrema is a small genus of fungi in the family Odontotremataceae. It comprises two species. The genus was circumscribed by Martha Allen Sherwood and Brian John Coppins in 1980. The type species, Xerotrema megalospora, is found in the United States and Canada. X. quercicola was added to the genus in 2008. These fungi produce tiny, deeply cup-shaped fruiting bodies on weathered, barkless wood of conifers and hardwoods in temperate regions. While the genus was originally thought to be non-lichenized, at least one species appears to form facultative partnerships with green algae, meaning it can survive with or without an algal partner.

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