The mollissima-subgroup of Pont (1965) belongs to the Fannia serena species-group of Chillcott (1961) in the genus Fannia Robineau-Desvoidy, 1830 (family Fanniidae). A review of the F. mollissima-subgroup, previously known from eleven species, is enlarged to include seven additional species: F. albisquama Wang & Zhang, sp. n., F. biseta Wang & Zhang, sp. n., F. doxonglaensis Wang & Zhang, sp. n., F. mainling Wang & Zhang, sp. n., F. multiseta Wang & Zhang, sp. n., F. nigribasicosta Wang & Zhang, sp. n., and F. tibetana Wang & Zhang, sp. n. A key to the known species of the F. mollissima-subgroup is given. To facilitate comparison of the species, the original diagnosis of the F. mollissima-subgroup has been expanded. The biogeography of the subgroup is discussed, including its origin and evolutionary history, the effect of the uplift of the Tibetan Plateau, and the effect of glacial periods during the Quaternary.