taxonID	type	description	language	source
11488784FFEDFF83FB3CAEBFFDE5DE53.taxon	diagnosis	Diagnosis. The new genus differs from Isopterygiopsis in having terete or indistinctly complanate vs. strongly complanate foliage; leaves often homomallous to falcate-secund vs. straight to slightly homomallous; plants autoicous or apparently dioicous (only one sex is known) vs. dioicous; operculum high conic vs. rostrate. Type species: Isopterygiella pulchella (Hedw.) Ignatov & Ignatova (= Leskea pulchella Hedw.).	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFEDFF83FB3CAEBFFDE5DE53.taxon	description	Description. Plants small or minute, green or yellowish-green, silky glossy, in small soft patches. Stems terete-foliate or indistinctly complanate, sparsely and irregularly branched; central strand present; hyalodermis well-developed or absent, in the latter case epidermal cells with thinner outer walls; rhizoids axillary, purple, coarsely papillose. Leaves straight or slightly falcate-secund, ovate-lanceolate to lanceolate, narrowly acute or acuminate; margins entire or serrulate near apex or throughout; costa short, double; laminal cells linear, basalmost cells shorter and wider, alar cells not differentiated or few alar cells quadrate to short rectangular. Specialized asexual reproduction by axillary propagulae of 3 – 4 cells in one row. Autoicous or apparently dioicous (male plants unknown). Inner perichaetial leaves short. Capsules erect to inclined, cylindric to slightly, rarely moderately curved. Operculum conic, sometimes with an apiculus. Annulus revoluble, of 2 – 3 rows of cells. Peristome slightly reduced; exostome teeth whitish, striolate below, papillose above; basal membrane of endostome ca. 40 % of exostome teeth length, segments narrow, not perforated, cilia 1 – 2, short to about as long as exostome teeth, nodose. Spores 10 – 15 µm. Calyptra cucullate. The genus inclides two species.	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFEFFF83F8C2AF7AFB6CDCD4.taxon	description	Isopterygiopsis Z. Iwats. Plants small, green or yellowish-green, strongly silky glossy, in loose tufts. Stems strongly complanate, irregularly branched; central strand absent or present, occasionally consisting of few cells; hyalodermis well-developed, rhizoids axillary, purple, coarsely papillose. Leaves apparently distichous, very rarely slightly secund (when growing in inappropriate habitats), ovate-lanceolate to ovate, gradually acuminate or abruptly narrowed into piliferous apiculus, moderately to strongly concave, occasionally cucullate; margins entire; costa short, double; laminal cells linear, basal cells shorter and wider, alar cells not differentiated. Specialized asexual reproduction by axillary propagulae of 3 – 4 cells in one row. Dioicous. Inner perichaetial leaves short. Capsules erect, rarer inclined, cylindric or slightly curved. Operculum rostrate. Annulus of 1 – 2 (– 3) rows of cells. Peristome moderately reduced; exostome teeth whitish or yellowish, striolate below, papillose above; basal membrane of endostome low, ca. 30 % of exostome teeth length, segments narrow, not perforated, cilia 1 (– 2). Spores 8 – 15 (– 17) µm. Calyptra cucullate. Type species: Isopterygiopsis muelleriana (Schimp.) Z. Iwats. (typified by Z. Iwatsuki, who however treated this species in a wide sense, including ‘ Orthothecium catagonioides ’ and keeping in mind solely Asian plants which we refer to a separate species). The genus inclides two species.	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFEFFF82FB3CACC5FBEADFBE.taxon	description	Stems to 2 cm long, central strand consisting of few cells present, rarer lacking. Leaves erect-spreading to spreading, loosely or densely arranged, (0.5 –) 1.0 – 1.5 × (0.2 –) 0.3 – 0.4 mm, ovate-lanceolate, gradually attenuate, with 1 – 2 - seriate apical portion 2 – 4 cells long, moderately concave, not cucullate; margins flat, entire; laminal cells 60 – 100 (– 120) × 4 – 5 µm, alar cells not differentiated. Specialized asexual reproduction by axillary propagulae of 3 – 4 cells in one row. Sporophytes rare, unknown in Russia. [Perichaetial leaves gradually narrowed into narrow acumen with serrulate margins. Setae 1.2 – 1.5 cm. Capsules ca. 1.2 mm long, erect, straight to weakly curved. Spores 10 – 14 µm].	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFEFFF82FB3CACC5FBEADFBE.taxon	distribution	Distribution and ecology. Isopterygiopsis muelleriana is a mountainous species occurring in South and Central Europe and extending northward to the southern areas of Norway (Hodgetts & Lockhart, 2020); it was also reported from Turkey (Ros et al., 2013), Africa (Kenya, Tanzania, Uganda) (O’Shea, 2006) and India (Gangulee, 1978 - 1980). Isopterygium sericifolium Dixon described from Kenya was synonymised with Isopterygiopsis muelleriana by Hedenäs (2001); specimen in BM (000674451) is habitually similar to European plants, as well as the drawing of leaf and shoot (https: // data. nhm. ac. uk / dataset / 56 e 711 e 6 - c 847 - 4 f 99 - 915 a- 6894 bb 5 c 5 dea / resource / 05 ff 2255 - c 38 a- 40 c 9 - b 657 - 4 ccb 55 ab 2 feb / record / 4522883). Illustration in Gangulee (1978 - 1980) (Fig. 1014) also shows a plant similar to European specimens rather than North Asian ones. Both I. muelleriana and I. catagonioides occur in China. The latter species was decribed from Shaanxi Province; illustrations in “ Moss Flora of China ” (Zhang & He, 2005) also show a stem transverse section without central strand and ovate leaves abruptly narrowed into short filiform apiculus. At the same time, molecular data confirm the presence of I. muelleriana in China (Yunnan) (Figs. 1 & 2).	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFEFFF82FB3CACC5FBEADFBE.taxon	description	Isopterygiopsis muelleriana is also considered to be widespread in eastern North America. However, its distribution in these areas needs confirmation because I. catagonioides was included into it. Illustrations in Flora of North America (Ireland Jr., 2014) likely represent I. catagonioides rather than I. muelleriana. Photograph of stem transverse section that lack central strand and has the whole cortex of rather few cells is provided by Faubert (2014), and illustrations in “ Flora of Maine ” by Allen (2014) also show plants which are much more similar to O. catagonioides than to I. muelleriana s. str. The only trn L-F sequence of I. muelleriana from North America in Genbank is also resolved within the clade of O. catagonioides (Fig. 2), as well as nad 5 region (AY 908764), cf. Fig. 3. In European Russia I. muelleriana is known only in the Caucasus where it was collected in Dagestan and Karachayevo-Circassian Republics; collections from Dagestan represent strongly depressed plants with small leaves (Fig. 4: 11 - 12, 7 A). These specimens were collected at altitudes 1900 – 2100 m on open slopes, on soil among grasses and rock outcrops. Plants from Karachayevo-Circassian Republic are better developed, similar to the specimen from Germany. Label data do not provide exact ecological information except for growing on soil. A single collection of I. muelleriana from Asian Russia was made in a valley of Bureya River, within forest zone, at 370 m elevation. It grew in a flood valley, on soil bank in forest, forming thin, lax patch and being represented mainly by tiny, depressed plants with small, distantly arranged leaves and attenuate stem and branch apices.	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFEFFF82FB3CACC5FBEADFBE.taxon	materials_examined	Additional specimens examined: EUROPE: GERMANY, Tegernsee, 6. I. 1919, Herzog, Paul & Schellenberg s. n. (MW 9045910). RUSSIA: Karachayevo-Circassian Republic: gorge of Daut River, 5. VIII. 1999, Ukrainskaya 13913 (LE). Dagestan: Charoda Distr., Gunukh, Ignatov & Abakarova 11 - 206 & 11 - 218 (MHA 9038321 & 9038319).	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFEFFF82FB3CACC5FBEADFBE.taxon	description	Differentiation. Isopterygiopsis muelleriana has ovate-lanceolate leaves more or less gradually tapered and ending with narrow, filiform apiculus. In leaf shape it is similar to Isopterygiella pulchella. However, Isopterygiopsis muelleriana has well-developed stem hyalodermis and complanate foliage, while hyalodermis in stems of Isopterygiella pulchella is absent or scarcely recognized, its stems are terete-foliate or leaves are secund. The distinctions from I. catagonioides are discussed under that species. Isopterygiella alpicola is another plant with well-developed stem hyalodermis and gradually acuminate leaves; it differs from Isopterygiopsis muelleriana in smaller size of plants, with leaves 0.3 – 0.8 × 0.1 – 0.3 mm vs. 1.0 – 1.5 × 0.3 – 0.5 mm; terete foliate stems, often falcate-secund leaves; serrulate vs. entire leaf margins; and shorter laminal cells, 30 – 60 × 5 – 9 µm vs. 60 – 100 (– 120) × 4 – 5 µm.	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFE9FF85F8C2A8E2FADCDEC8.taxon	description	Stems 1 – 2 (– 2.5) cm long, central strand lacking. Leaves appressed, densely arranged, often imbricate, (0.8 –) 1.0 – 1.3 × 0.4 – 0.5 mm, ovate, abruptly contracted into filiform, flexuose to reflexed apiculus ca. 0.1 mm long, strongly concave, often cucullate; margins flat, entire; laminal cells 55 – 90 × 4 – 6 µm, alar cells not differentiated. Specialized asexual reproduction by axillary propagulae of 3 – 4 cells in one row sporadically present. Dioicous. Sporophytes rare. Inner perichaetial leaves 1.3 – 1.4 × 0.3 mm, abruptly contracted into long acumen, margins coarsely dentate above. Setae ca 0.8 cm. Capsules to 1.0 mm long, erect to slightly inclined, straight to slightly curved. Spores 13 – 17 µm.	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFE9FF85F8C2A8E2FADCDEC8.taxon	distribution	Distribution and ecology. This species is sporadically distributed in mountain areas in Asian Russia, from the Arctic to southern Siberia and Far East. In European Russia it is known from Polar Urals. It also apparently occurs in China and North America (see comments to I. muelleriana; furthermore, one duplicate specimen of this species from Canada is stored in MHA). However, its distribution in these territories needs further study. Isopterygiopsis catagonioides grows in a wide altitudinal range, from sea level (in Iturup Island, Kurils) to 2000 m (in Altai Mts.), in shady cliff crevices and cracks, between rocks of rock-fields, on rock outcrops, in mountain tundra, on cliffs near waterfalls and more or less dry cliffs, in forests and on open slopes, rarely on tree bases, rotten wood and bare soil in forests; it prefers acidic and neutral rocks. Additional selected specimens examined: EUROPE: RUSSIA: Republic of Komi: Subpolar Urals, Malaya Nyadokota River (tributary of Lemva River), 21. IV. 1950, Kil’dyushevsky s. n. (LE); Subpolar Urals, Saranseda Creek (upper right tributary of Kozhim River), 19. IV. 1950, Kil’dyushevsky s. n. (LE).	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFE9FF85F8C2A8E2FADCDEC8.taxon	materials_examined	ASIA: RUSSIA: Yamalo-Nenetzky Autonomous District: Junto Lake, 14. VIII. 1994, Czernyadjeva 16 (LE); Polar Urals, middle course of Sob’ River, railway station 110 km, 6. VII. 1988, Czernyadjeva 7 (LE). Krasnoyarsk Territory: Taimyr Municipal Distr.: Putorana Plateau, Glubokoe Lake, Fedosov 15 - 0366 (MW 9046852); vicinity of Khatanga Settl., valley of Merkyu River, Fedosov 11 - 1382 (MW 9046849); Anabar Plateau, near Fomich River mouth, Fedosov 08 - 581 (MW 9045911); Maimecha River at 11 km upstream Chopko Creek mouth, Fedosov 09 - 416 (MW 9045912); Kotuikan River at 7 rm upstream Merkyu River mouth, Fedosov 11 - 1489 (MW 9045916). Republic of Buryatia: Barguzinsky Distr., Barguzinsky Nature reserve, Davsha Settl., Czernyadjeva 64 - 14 (MW 9112304); Kabansk Distr., Khamar-Daban Range, valley of Bolshoy Mamai Creek, Ignatov, Ignatova & Kolesnikova 18 - 4014 (MW 9090512). Zabaikalsky Territory: Kalar Distr.: vicinity of Kuanda Settl., 4. VIII. 2012, Afonina s. n. (MW 9045918); vicinity of Udokan Settl., Udokan Range, 28. VII. 1985, Filin s. n. (MW 9045919). Republic of Yakutia: Oimyakon Distr., Suntar-Khayata Range, Mus-Khaya Mt., Ignatov & Ignatova 11 - 3250 (MW 9045925); Tomponsky Distr.: Suntar-Khayata Range, Kyurbelyakh Creek, Ignatov & Ignatova 11 - 2233 (MW 9045924); Dyby River, Ignatov & Ignatova 17 - 430 (MW 9090155); Momsky Distr., Ulakhan-Chistai Range, middle course of Tirekhtyakh River, Tas Creek, Ignatov & Ignatova 18 - 2127 (MW 9091656). Khabarovsk Territory: Verkhnebureinsky Distr.: Bureinsky State Reserve, Dusse-Alin Range, Medvezh’e Lake, 5 Ignatov 97 - 338 (MW 9038116); left bank of Bureya River near “ Tri Brata ”, Ignatov 97 - 342 (MW 9038115); Sovgavansky Distr.: Botchinsky State Reserve, Mulpa River opposite Podzemny Creek mouth, Ignatov & Ignatova 13 - 167 (MW 9045928); Badzhal Mts., Yarap River valley, Fedosov 16 - 30 (MW 9112951); North Sikhote-Alin, Tardoki-Yani Mt. Range, Sukhaya Pad’ Stream, 28. VIII. 2013 Ermolenko 12 - 8 (MW 9111159). Amurskaya Province: Zeya Distr., Zeisky Nature reserve, Tukuringra Range, Izyubriny Creek, 28. VI. 2012, Dudov Br _ 12 _ 084 (MW 9045931); Selemdzhinsky Distr., Norsky Nature Reserve, Meun River, 5. VII. 2010, Bezgodov 127 (MHA 9038166). Primorsky Territory: Olga Distr., waterfall on Milogradovka Creek, Ignatov 07 - 296 (MW 9045930); Chuguevka Distr., Oblachnaya Mt., Ignatov 07 - 263 (MW 9045941); Partizansk Distr., Olkhovaya Mt., Ignatov, Ignatova & Cherdantseva 06 - 2672 (MW 9045940); Shkotovo Distr., Pidan (Livadijskaya) Mt., Ignatov & Ignatova 06 - 2274 (MW 9045937). Sakhalinskaya Province: Sakhalin: Dolinsk Distr., Sokol, Belaya Creek, Ignatov & Teleganova 06 - 819 (MW 9045938); Tymovsk Distr., Nabilsky Mt. Range, along a tributary of Khrebtovyj Creek, Ignatov & Teleganova 06 - 902 (MW 9045939); Kuril Islands: Iturup Island: Bogatyr Range, Bakalin K- 16 - 38 - 07 (MW 9045943); vicinity of Circ Bay, 45.32366 ° N, 148.6187 ° E, Fedosov 15 - 2 - 216 (MW 9046853); Kunashir Island: atrio of Tyatya Volcano, Ignatov 06 - 1754 (MW 9045936). Kamchatsky Territory: Kamchatka Peninsula: Klyuchevskie Volcanoes, Ostryj Tolbachik Volcano, 6. VIII. 2006, Czernyadjeva 8 (MW 9045952); Kronotskyj State Reserve, Krasheninnikov Volcano, Fedosov 12 - 224 (MW 9045953); Aleutsky Distr., Bering Island, Bolshaya Stolovaya Sopka, Fedosov 10 - 3 - 1124 (MW 9045955).	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
11488784FFE9FF85F8C2A8E2FADCDEC8.taxon	description	NORTH AMERICA: Canada, New Brunswick, Restigouche Co., 14 Aug 1970 Ireland (MHA 9054883). Differentiation. Isopterygiopsis catagonioides differs from I. muelleriana in having abruptly vs. gradually narrowed leaf acumina; strongly concave, often cucullate vs. moderately concave, not cucullate leaves; and densely vs. often + sparsely foliate stems. Due to ovate leaves with abruptly attenuate apiculus, I. catagonioides can be confused with widespread Siberian Plagiothecium svalbardense and European Rectithecium piliferum, both having similar leaf shape. However, I. catagonioides differs from both these species in flat leaf margins and presence of stem hyalodermis vs. narrowly recurved margins from base to apiculus and hyalodermis not developed.	en	Ignatova, E. A., Fedorova, A. V., Ignatov, M. S. (2020): On the genera Isopterygiopsis and Isopterygiella, gen. nov. (Plagiotheciaceae) in Russia. Arctoa 29 (1): 49-62, DOI: 10.15298/arctoa.29.03, URL: https://doi.org/10.15298/arctoa.29.03
