Cryptomarasmius gen. nov. established in the Physalacriaceae to accommodate members of Marasmius section Hygrometrici.

Phylogenetic placement of the infrageneric section Hygrometrici (genus Marasmius sensu stricto) in prior molecular phylogenetic studies have been unresolved and problematical. Molecular analyses based on newly generated ribosomal nuc-LSU and 5.8S sequences resolve members of section Hygrometrici to the family Physalacriaceae. The new genus Cryptomarasmius is proposed to accommodate members of Marasmius section Hygrometrici. Fourteen species belonging to section Hygrometrici whose available type specimens bear morphological features corresponding to the new genus are formally combined in Cryptomarasmius. Taxonomic transfers are made only for taxa in which type specimens have been studied and/or representative material sequenced. Although other species placed in section Hygrometrici may belong in Cryptomarasmius, further transfers are not proposed until additional studies on type material are conducted.