Fedosov, V.E., I.V.Czernyadjeva, E.A. Ignatova, O.I. Kuznetsova, A.V. Fedorova & M.S. Ignatov. On the Bryoxiphium norvegicum and B. japonicum (Bryoxiphiaceae, Bryopsida)
Arctoa (2016) 25: 52–68
Bryoxiphium japonicum was accepted as a subspecies of B. norvegicum in the world revision of the genus by Б. Löve & D. Löve (1953) and treated in the recent literature at this rank. However, ITS sequence data indicate a strong genetic difference between plants from the southern part of Russian Far East (mainland, Sakhalin and Kuril Islands), Japan and China, and plants from the northern part of Russian Far East (Chukotka, Kamchatka, Commander Islands), Transbaikal Siberia, south-east Yakutia, and also from North America and Iceland. Low genetic variation over the expanded range of B. norvegicum s. str. and its sharp differentiation of sequences from East Asian plants suggest the resurrection of Bryoxiphium japonicum as a separate species. Additional comparison of these two taxa confirmed the diagnostic value of previously used morphological characters and revealed new ones, allowing the identification of plants in sterile state. Bryoxiphium japonicum differs from B. norvegicum in longer filiform awns in perichaetial and perigonial leaves with sharply serrate vs. slightly crenulate or subentire margins, higher dorsal lamellae in stem leaves, presence of attenuate filiform acumen in stem leaves, and shorter cells at the base of stem leaves.