Molecular analyses have consistently evidenced the phylogenetic heterogeneity of Orthotrichum Hedw., and suggested the need to segregate the species with superficial stomata in a separate genus. A recent proposal has been made to accommodate the monoicous species with such stomata in the genus Dorcadion Adans. ex Lindb., which is, however, an illegitimate name according to the current Code of nomenclature of algae, fungi and plants. Consequently a new name is required, and the generic name Lewinskya F.Lara, Garilleti & Goffinet is proposed. New combinations are made for all the species included in the new genus. Given the long history of the genus Orthotrichum and the similarities between this genus and Lewinskya, the morphological and geographic circumscriptions of both genera are provided to define them accurately. The taxa remaining in Orthotrichum s.str. are also listed.