Macromitrium nepalense is characterized by its irregularly 1–3-layered upper lamina with pluripapillose cells on both dorsal and ventral surfaces. This peculiar and important feature has been overlooked or incorrectly stated by all recent taxonomic literature in circumscribing the species. The study provides a revised circumscription of Macromitrium nepalense and revealed that the surface structure of the upper lamina as shown in the cross-section is essential to the understanding of many Macromitrium species. Four additional species of Macromitrium have been found with such a peculiar feature. Macromitrium incrustatifolium and M. longibrachteatum are reduced to synonymy with M. nepalense based on the overall similarities of their gametophytic features; while M. serpens and M. tongense remain distinct from M. nepalense by having elongate, curved and sigmoid basal cells.