Dictyonema irrigatum is a species of basidiolichen in the family Hygrophoraceae. It was originally described as a new species in 1860 by Miles Joseph Berkeley and Moses Ashley Curtis, who classified it as a member of the fungal genus Corticium. In their Latin description, Berkeley and Curtis characterized the species as having a thin, reflexed cap with a wrinkled- (woolly) surface and a smooth, cream-coloured hymenium (spore-bearing surface). They noted that it formed dense patches on rocks and recorded the type locality as Hong Kong. Robert Lücking transferred the species to the genus Dictyonema in 2013.