Cryptothallus is a genus of liverworts in the family Aneuraceae. The plants are small, and are white to pale green as a result of lacking chlorophyll. The morphology of Cryptothallus is very similar to that of Aneura. As a result, Renzaglia, has suggested it may be considered "merely as an achlorophyllous species of Aneura." Wickett and Goffinet have argued the same position on the basis of sequences of nuclear, mitochondrial, and plastid DNA.