Annulohypoxylon, sometimes called cramp balls, is a genus of fungi in the family Xylariaceae. The 27 species in the genus have a collectively widespread distribution.

The genus Annulohypoxylon was created in 2005 and contains species formerly placed in the closely related genus Hypoxylon (it is equivalent to Hypoxylon section Annulata sensu). Fossils of Annulohypoxylon have been found in 12 million year old rocks from central England.

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