Tortella tortuosa (Hedw.) Limpr., Laubm. Deutschl.

Tortella tortuosa (Hedw.) Limpr., Laubm. Deutschl. View in CoL 1: 604. 1888. — Tortula tortuosa Hedw., Sp. Musc. Frond. 124. 1801.

This species is widespread throughout Holarctic (it is absent only in areas without rocky substrates), as well as in Central and South America. It is common in mountain areas of Russia and found in some its lowland provinces. However, in Russian Arctic it is substituted by other species of the genus: Tortella fleischeri in European part and Novaya Zemlya, T. splendida , T. cuspidatissima , and T. spitzbergensis in Asian sector of the Arctic, except Chukotka, where it is not rare and may co-occur with aforementioned species. Few specimens from Polar Ural (Yamalo-Nenetz Autonomous District) also belong to T. tortuosa . This species is readily recognized by combination of such characters as stems lacking central strand; leaves with parallel margins at mid-leaf, contorted and crisped when dry, wavy at margins, with costa papillose on ventral surface, and usually thin-walled, hyaline basal cells, abruptly delimited from limb cells with v-shaped boundary, reaching high up along margins. Its distinctions from other species of the genus occurring in Rissian Arctic are discussed in comments to these species.