Unearthing the identity, taxonomy and nomenclature of the enigmatic Marchantiopsis stoloniscyphula (Marchantiophyta, Marchantiaceae) from China

Owing to a combination of reportedly unique morphological characters and an unlocatable type specimen, Marchantiopsis stoloniscyphula has been regarded as an enigmatic species in Marchantiaceae since its description, and all subsequent taxonomic treatments of this species were made without examination of the type. We located the original material of M. stoloniscyphula which was included as an admixture within the holotype of Wiesnerella fasciaria deposited in IFP. Our morphological examination found that M. stoloniscyphula and W. fasciaria are conspecific with Marchantia papillata subsp. grossibarba and Sandea japonica, respectively. The nomenclature of Marchantiopsis and M. stoloniscyphula are discussed. Lectotypes for M. stoloniscyphula and W. fasciaria are also designated.