Fedosov, V.E., Y.-M. Wei, B.C. Ho, J. Atwood, O.I. Kuznetsova & M.S. Ignatov. 2024. The genus Fissidens in Russia, III: Fissidens kiusiuensis (Bryophyta), a new species for the Russian Far East

Arctoa (2024) 33: 107–116

doi: 10.15298/arctoa.33.12

Among recent collections of mosses from the Ussurijsky Nature Reserve (Primorsky Territory, Russia) we found a very small Fissidens species, which did not match any species description in its combination of morphological traits. The species resembles the North American F. closteri subsp. closteri in the mostly subentire leaf margins and having only a few stereids in the costa, but in its scabrous calyptrae it also matches the East Asian F. closteri subsp. kiusiuensis. Molecular phylogenetic study found that the nuclear ITS of these plants is subidentical with Chinese plants from Guangxi Province, and strongly different from the North American plants. Morphological variation in Asian populations is found to be broader than previously described. Therefore we suggest resurrection of Fissidens kiusiuensis as a separate species. The finding in Guangxi Province is the third record of this species in China. A correction is made regarding the citation of lectotype specimen of F. closteri in the NY herbarium.