taxonID	type	description	language	source
046B87D8FFB55540FF36FB19FAE3F9A1.taxon	distribution	Distribution and ecology. Tortella splendida is an arcto-alpine species, occuring in Asian and North American Arctic regions, in the mountains of Central Europe (Köckinger & Hedenäs, 2023), Caucasus (Kuznetsova et al., 2023), southern Siberia, Russian Far East (our data), China (Eckel, 2007), and in North America in Colorado and Maine (Eckel, 2007). It is common in northern Taimyr and Chukotka, especially on Vrangel Island. It grows on gravelly soil, in niches between rocks of rockfields, rock crevices, on rocks outcrops, especially in areas with calcareous bedrocks; it also occurs along brooks and in polygonal and spotty tundra, where it forms large pure fufts or grows among other mosses. Differentiation. Tortella splendida is similar to T. tortuosa in having leaves with costa papillose on ventral surface and stems lacking central strand. However, its leaves are straight when wet (usually sigmoid and often secund in T. tortuosa); their limbs are gradually narrowing from above base (limbs have parallel margins for a long distance in T. tortuosa); leaf margins are not wavy (usually strongly wavy in T. tortuosa); transition between basal and limb cells is gradual (mostly abrupt, V-shaped in T. tortuosa), elongate basal cells do not extending high along leaf margins (reach far up in T. tortuosa); it also has less tomentose stems (often densely tomentose in T. tortuosa). Basal cells are usually yellowish in arctic plants of T. splendida, contrary to white basal cells of T. tortuosa. Unlike T. splendida, T. tortuosa never possess two layers of guide cells in costa. There is some similarity in leaf shape between T. splendida and T. cuspidatissima, but the latter species can be readily separated by having leaf costae smooth ventrally and stems with weak central strand. Also in T. s plendida on average cells in the upper part of the leaf are smaller (7 – 11 µm vs 11 – 16 µm in T. cuspidatissima) and costa is wider (100 – 150 (– 200) µm vs 50 – 100 (120) µm in T. cuspidatissima).	en	Ignatova, E. A., Czernyadjeva, I. V., Fedorova, A. V., Fedosov, V. E. (2024): On the genus Tortella (Pottiaceae, Bryophyta) in Russian arctic. Arctoa 33 (2): 195-209, DOI: 10.15298/arctoa.33.20, URL: https://doi.org/10.15298/arctoa.33.20
046B87D8FFB5554EFCBCF990FDBFFB41.taxon	distribution	Distribution and ecology. This species was described from Spitzbergen (Norway). In Russian handbooks and check-lists it was provided under the name Trichostomum cuspidatissimum (Savicz-Lyubitskaya & Smirnova, 1970; Ignatov et al., 2006). Werner et al. (2014) also confirmed the presence of Tortella spitzbergensis Canada (Newfoundland) and in Russia (Arctic Siberia and Chukotka). In the course of our study, we found it to occur on Novaya Zemlya and being common on Northern Taimyr and Chukotka. Outside Arctic, it is known in Russia in Anabar Plateau, Yakutia, Magadan Province, Kamchatka, Khabarovsk and Zabaikalsky Territories, Buryatia and Tyva. It grows in wet arctic and mountain tundra, boggy sites, on rocky slopes, screes, wet rock outcrops, often on calcareous rocks. Differentiation. Tortella spitzbergensis differs from all other species of the genus in having large, sharply delimited stem central strand; it is formed of very thin-walled, numerous small cells surrounded by firm-walled cells of central cylinder. Presence of stem central strand, costa smooth on ventral surface, leaves with wide-ovate bases and comparatively short, lanceolate acumina differentiate T. spitzbergensis from T. splendida. Tortella cuspidatissima possesses stem central strand, but the small one; it also has gradual transition between basal and limb cells, but its juxtacostal basal cells reach into the limb at the same height as the marginal ones; its basal marginal cells are only slightly wider than central cells, of the same width or narrower.	en	Ignatova, E. A., Czernyadjeva, I. V., Fedorova, A. V., Fedosov, V. E. (2024): On the genus Tortella (Pottiaceae, Bryophyta) in Russian arctic. Arctoa 33 (2): 195-209, DOI: 10.15298/arctoa.33.20, URL: https://doi.org/10.15298/arctoa.33.20
046B87D8FFBB554EFF36FB30FB49F981.taxon	distribution	Distribution and ecology. Tortella cuspidatissima was described from Hall Island near NW coast of North America, which remains its only known locality in this continent. Werner et al. (2014) considered it as a species of hybrid origin with parent species T. arctica (= T. splendida) and T. spitzbergensis. They also found it in Sweden. Köckinger & Hedenäs (2023) referred to T. cuspidatissima type specimens of T. arctica from the lower course of Lena River. We also found it in herbarium collections from Chukotka and Vrangel Island. It grows on soil in wet arctic tundra, on moist calcareous rocks with soil layer, along streams, and on pebbly sea shore terrace. Differentiation. Tortella cuspidatissima differs from T. tortuosa and T. splendida by presence of stem central strand (though occasionally indistinct) and smooth costa on ventral surface, and from the former species also by gradual transition between basal and limb cells. Small central strand, 2 – 4 cells wide, differentiates T. cuspidatissima from T. spitzbergensis (in the latter species central strand is usually very conspicuous, large, 7 – 14 cells wide, only very rarely + small). In T. cuspidatissima stems are round in transverse section, while in T. spitzbergensis they are triangular in outline. Basal cells reach into the limb at equal height at margins and near costa in T. cuspidatissima, but higher near costa in T. spitzbergensis. In T. cuspidatissima basal marginal cells are narrower or lightly wider than central cells, whereas in T. spitzbergensis several marginal cell rows at leaf base are distinctly wider and shorter, forming pellucid area. An additional character is the width of upper and median laminal cells: (7 –) 11 – 14 (– 16) µm in T. cuspidatissima vs. 8 – 11 (– 13) µm in T. spitzbergensis. Tortella fleischeri, with also posesses weak central strand and costae smooth ventrally, can be distinguished by abrupt transition between basal and limb cells (Fig. 6).	en	Ignatova, E. A., Czernyadjeva, I. V., Fedorova, A. V., Fedosov, V. E. (2024): On the genus Tortella (Pottiaceae, Bryophyta) in Russian arctic. Arctoa 33 (2): 195-209, DOI: 10.15298/arctoa.33.20, URL: https://doi.org/10.15298/arctoa.33.20
046B87D8FFBB554BFCBCF9F0FDABFAAE.taxon	distribution	Distribution and ecology. This species was described from Austria. Köckinger & Hedenäs (2023) characterize it as calciphilous and cryophilous species, usually growing above tree line. Outside the Alps, they report it from Slovakia, Montenegro, and Scotland, considering its presence in the latter locality as surprising, as it is usually substituted in the north of Europe by ecologically similar T. cuspidatissima and T. spitzbergensis. Nevertheless, in Russia it was discovered in the northeastern European part, where T. cuspidatissima was not found and T. spitzbergensis was recorded only on Novaya Zemlya. Tortella fleischeri was identified in collections from Nenetz Autonomous district, on Yugorsky Peninsula and Vaigach Island. It was also revealed in collections from Novaya Zemlya (belongs to Arkhangelsk Province) and Yamalo-Nenets Autonomous District in the north of West Siberia. According to the label data, Tortella fleischeri grew on gravely substrate in different types of tundra. Differentiation. Specimens from Russia were stored in herbaria under the names T. tortuosa and T. cf. arctica. From both these species T. fleischeri differs by presence of stem central strand (however, sometimes indistinct) and narrow strip of smooth cells along ventral surface of costa. From T. cuspidatissima and T. spitzbergensis, which also have stem central strand and costa smooth ventrally, T. fleischeri (at least specimens from Russian Arctic) differ in having abrupt, V- or U-shaped transition between basal and limb cells (Fig. 6).	en	Ignatova, E. A., Czernyadjeva, I. V., Fedorova, A. V., Fedosov, V. E. (2024): On the genus Tortella (Pottiaceae, Bryophyta) in Russian arctic. Arctoa 33 (2): 195-209, DOI: 10.15298/arctoa.33.20, URL: https://doi.org/10.15298/arctoa.33.20
