Ostreichnion Duby, Mém. Soc. Phys. Hist. nat. Genève 16(1): 33 (1862).
MycoBank number: MB 3645; Index Fungorum number: IF 3645; Facesoffungi number: FoF 00163; – 3 morphological species (Boehm et al. 2009a), 3 species with molecular data.
Type species – Ostreichnion americanum Duby, Mém. Soc. Phys. Hist. nat. Genève 16(1): 34 (1862).
Notes – Ostreichnion, previously placed in the Mytilinidiaceae, has been transferred to Hysteriaceae (Boehm et al. 2009a). This was based on sequence data derived from two of the three species, O. curtisii (CBS 198.34) and O. sassafras (CBS 322.34), deposited by Lohman (1934). The genus is characterized by dictyospores or large didymospores ascospores borne in choncate mytilinidioid, fragile fruitbodies, with thin-walled slerenchymatous cells.