Cryptothallus is a previously recognized genus of liverworts in the family Aneuraceae. The plants are small, and are white to pale green as a result of lacking chlorophyll. This feature led to the creation of a separate genus.[1] The morphology of species assigned to Cryptothallus is very similar to that of Aneura. As a result, Karen Renzaglia in 1982 suggested that the only species then placed in the genus, Cryptothallus mirabilis, may be considered "merely as an achlorophyllous species of Aneura."[2] Wickett and Goffinet argued the same position on the basis of sequences of nuclear, mitochondrial, and plastid DNA, and moved Cryptothallus mirabilis to Aneura.[3] A 2010 molecular phylogenetic study confirmed the position of Cryptothallus within Aneura.[4] This was accepted in the 2016 world checklist of hornworts and liverworts.[5]
Two species were formerly placed in the genus.[5]