Origin and relationships of the myco‐heterotrophic liverwort Cryptothallus mirabilis Malmb. (Metzgeriales, Marchantiophyta)

Heterotrophic life histories have evolved independently numerous times in the angiosperms. In non‐vascular embryophytes, heterotrophy is known only in the genus Cryptothallus . Cryptothallus mirabilis obtains photosynthates indirectly from a host tree via a basidiomycete that is simultaneously ectomycorrhizal on the host, a strategy known as myco‐heterotrophism. This simple thalloid liverwort was initially described as an albino variant of Aneura pinguis , and the literature varies on whether it should be considered as such, as a distinct species of Aneura , or as a separate genus. Here, the relationships of C. mirabilis within the family Aneuraceae are reconstructed using DNA sequence data from the chloroplast ( rps 4, rps 14, atp B‐ rbc L spacer, trn G), mitochondrial ( trn S), and nuclear (26S and ITS) genomes. Several allopatric populations of C. mirabilis and of both sympatric species of Aneura (i.e. A. pinguis and A. maxima ) were included. Cryptothallus mirabilis is resolved as having a single origin from within Aneura , and hence the myco‐heterotrophic liverwort should be considered as a distinct species of Aneura , rather than an autonomous genus. The fungal symbiont of the photosynthetic A. pinguis is of the same genus, Tulasnella , as that of C. mirabilis , suggesting that the heterotrophic life strategy might have evolved from a pre‐existing symbiosis. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 1–12.