Ignatova, E.A., H.H. Blom & O.I. Kuznetsova. Schistidium austrosibiricum sp. nov. and S. scabripilum sp. nov. (Grimmiaceae, Bryophyta) – two closely related species from Asian Russia
Arctoa (2016) 25: 107–115
Two new species of Schistidium are described from Asian Russia. Their distinctness is supported by nrDNA ITS1-2 sequence data. S. austrosibiricum was not previously differentiated from S. sinensiapocarpum, mainly due to their similarly long and sharply serrate hair-points in stem and perichaetial leaves and papillose dorsal side of costa. However, they differ in leaf size and shape, hair-points flatness and leaf lamina areolation. S. austrosibiricum is known from southernmost mountain areas of Asian Russia, while S. sinensiapocarpum is a widespread circumholarctic montane species. The second species, S. scabripilum is morphologically similar to S. echinatum, and some specimens were previously referred to it. The main differences between them concern hair-point length and structure, including length of protruding spinulae and their angle with the hair-point axis. However, they belong to different clades in the molecular phylogenetic tree and possess different distribution patterns. S. scabripilum is a northern Asian species, found in the Putorana Plateau, southern Taimyr, Yakutia and Chukotka, while S. echinatum is known from the Alps, Caucasus and Ural mountains, and in western North America. Description, illustrations, distribution and ecological data are provided for the new species, and comparison with similar species is given.