Plagiothecium svalbardense Frisvoll, Norsk Polarinst. Skr.

Plagiothecium svalbardense Frisvoll, Norsk Polarinst. Skr. View in CoL 198: 103. 1996. Figs. 9–10 View Fig View Fig .

Description. Plants small, lustrous, in somewhat loose mats formed by variously directed stems. Stems 0.6–2 cm long, subpinnately or irregularly branched, foliage indistinctly complanate. Leaves forming a 30–70° angle with stem, symmetric to strongly asymmetric, concave, (0.7–)1.2–1.6 × 0.35–0.6 mm, ovate, gradually tapered to the apex, with attenuate apiculus, sometimes almost piliferous; cells of decurrencies in 2–3 rows, rectangular; leaf margins entire or minutely denticulate shortly below the apex, narrowly recurved almost throughout; costa short and double, occasionally extending beyond midleaf; laminal cells 70–130 × 5–10 µm. Gemmae of 3–4 short rectangular cells, occasionally present. Autoicous. Sporophytes occasionally present. Setae 5–10 mm long; capsules straight and erect or slightly curved and more or less inclined, 1–1.2 mm long. Exostome teeth 400–450 µm long; basal membrane of endostome ca. 130 µm high, segments slightly shorter than exostome teeth, cilia 2, 150 µm long, nodose. Spores 10–12 µm.

Distribution and ecology. Plagiothecium svalbardense occurs throughout the territory of Asian Russia: in permafrost zone of Yakutia and Taimyr, Amur Province, Khabarovsk and Primorsky Territories, Sakhalin, Kamchatka, mountain areas of southern Siberia, and West Siberia; in European Russia, it grows in the Urals and northern areas of lowland part (Arkhangelsk and Murmansk Provinces, Karelia). Plagiothecium svalbardense grows on various substrates, including cliffs, rock outcrops, rocks, tree bases, stumps, and rotten wood.

Differentiation. According to the original description, P. svalbardense is characterized by subjulaceus foliation, ovate and distinctly apiculate leaves, and leaf cells 7–10 × 80–110 µm. Frisvoll in Frisvoll & Elvebakk (1996) emphasized that leaves of P. svalbardense are ovate and fairly suddenly narrowed into apiculus, while in P. laetum the leaves are more evenly narrowed into the short apex. He also stated that the majority of leaves in P. svalbardense are quite or almost symmetrical, while in P. laetum they are distinctly asymmetrical. In addition, he mentioned often subjulaceus and rarely complanate shoots

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of P. svalbardense View in CoL , which is contrasting with really complanate shoots of P. laetum View in CoL . All these observations were made solely on Svalbard material, wherefrom P. svalbardense View in CoL was known that time. Later Wynns et al. (2018) cited a specimen of Holmen and Mogensen from Greenland which they referred to P. svalbardense View in CoL . Since a large number of specimens from Russia, mainly from its Asian part, grouped in the molecular phylogenetic analysis based on sequences of nuclear and plastid DNA with this specimen from Greenland, it made us confident that P. svalbardense View in CoL has a much wider distribution than it was thought before. Our specimens agree with P. svalbardense View in CoL in most habitual and morphological characters mentioned by Frisvoll (1996) and detailed description and illustration of “ P. laetum View in CoL , Svalbard plant” given by Frisvoll (1981), except for always quite or almost symmetrical leaves: in many of our specimens, both symmetrical (“dorsal”) and strongly asymmetrical (“lateral”) leaves can be found (see Figs. 9–10 View Fig View Fig ). Actually, the descriptions of leaf symmetry by Frisvoll (1981) and by Frisvoll & Elvebakk (1996) are in some disagreement: in the former work leaves are described as both symmetrical and asymmetrical, sometimes strongly so, while in the latter publication it is stressed that leaves are more often symmetrical. Frisvoll (1981) writes that leaves of Svalbard plants are more or less gradually tapered, while later he emphasized a suddenly narrowed leaf acumen ( Frisvoll & Elvebakk, 1996). In our material from the wider distributional range, leaf shape (ovate leaves with suddenly narrowed acumen, sometimes resembling Rectithecium piliferum View in CoL ) is a very stable character of this species, as well as hardly flattened shoots. Leaf margins are always narrowly recurved in P. svalbardense View in CoL , often up to the base of attenuate apiculus (described as “narrowly recurved from base to apex” by Frisvoll, 1981). Width of laminal cells appeared to be even more variable in our material, 5–10 µm, as well as cell length, 70–130 µm. Sporophytes were not described by Frisvoll, apparently being absent in Sval-

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bard material. Thus, they are described above for the first time.

There is some resemblance in morphological traits between P. svalbardense and P. berggrenianum (ovate leaves with margins recurved from base to near the apex and suddenly narrowed apical part); however, the leaves of P. berggrenianum are much wider (0.8–0.9 mm vs. 0.35–0.6 mm), always symmetrical, leaf margins are more widely recurved, and the attenuate apical part is strongly curved and hook-shaped.

There is no problem to separate P. svalbardense from P. rossicum due to always narrowly recurved leaf margins in the former species and flat margins in the latter one; in addition, shoots of P. rossicum are hardly branched and distinctly flattened, while P. svalbardense has much more branched, scarcely flattened shoots. Regarding P. curvifolium, Frisvoll (1981) mentions the similarity of “ Svalbard P. laetum ” (= P. svalbardense ) with the former species in cell width, color of plants and structure of leaf decurrencies; at the same time, he states that P. curvifolium is a larger plant, it has different shape and orientation of leaves, and its distribution in Scandinavia is strictly confined to the range of conifer forest. These statements agree well with our observations of Russian material.

Selected specimens examined: EUROPEAN RUSSIA: Murmansk Province: Umba, Ignatov & Ignatova 12-140 ( MW9055491 ) ; Porja Guba, Kozhin M-M-0519 ( MW9055309 ) ; Alakurtti 30.VII.1971, Konstantinova s.n. ( MW9055318 ) ; Republic of Karelia: Loukhi Distr. , biostation “Kartesh”, 19.VII.2017, Zakharchenko s.n. ( MW9110792 ) ; Kostomukshsky Nature Reserve , 9.VII.1992, V.N. Korotkov s.n. ( MW9055311 ) ; Arkhangelsk Province: Pinega Nature Reserve , 5.VIII.2006, Stepanov II-2 ( MW9055023 ) ; same place, 30.VII.1988, Ignatov s.n. ( MHA9041588 About MHA ) ; Komi Republic: Pechoro-Ilychsky Nature Reserve, Seregin & Zakharov M-3425 ( MW9055632 ) ; Sosnogorsk Distr., Nizhny Odes , 5.VII.2007, Kucherov & Kutenkov 168 ( MHA9041472 About MHA ) ; Perm Province: Basegi Nature Reserve, Ignatov & Bezgodov 743 ( MW9055417 ) ; Vishersky Nature Reserve , 5.VII.1994, Bezgodov 379 ( MW9055427 ) ; Republic of Bashkortostan: Beloretzky Distr., projected Nature Park “Inzer”, 8.VII.2005, Shirokikh 222 A ( MW9055447 ) ; Zuyakovo Settl. , 1.VIII.1990, Muldashev 89 ( MW9055446 ) ; Bolshoy Iremel’ Peak , Ignatova 6/11 ( MHA9041659 About MHA ) . ASIAN RUSSIA: Tymen Province: Uvatsky Distr., Bartak River , 3. V.2013, Bezgodov 123 ( MW9055451 ) ; Altai Republic: Kaitanak , Ignatov & Ignatova 12-628 ( MW9055449 ) ; Ayulyuyuzyuk, Ignatov 0/384 ( MHA9041722 About MHA ) ; Yailyu, Ignatov 0/622 ( MHA9041717 About MHA ) ; Krasnoyarsk Territory: Taimyr Distr.: Kotuy River , Fedosov 13-3-1087 ( MW9055633 ) ; Ereechka River, Fedosov 13-3-0869 ( MW9055454 ) ; Baikit Distr., Stolbovaya River , 1992, Shcherbina s.n. ( MW9055461 ) ; Zabaikalsky Territory [Chita Province]: Naminga , 26.VII.1989, Filin s.n. ( MW9055465 ) ; Republic of Buryatia: Bol’shoy Mamai Creek , Ignatov et al. 18-4057 ( MW9090527 ) ; Republic of Sakha / Yakutia: Tomponsky Distr. , Dyby River , Ignatov & Sofronova 17-366 ( MW9090011 ) ; Sette-Daban, between Ulakh and Nadezhda Creeks , Ignatov & Ignatova 16-1045 ( MW9078473 ) ; Kyurbelyakh Creek , 63°08’N, 139°04’E, 8.VII.2011, Ignatov & Ignatova 11-2164 ( MW9055468 ) GoogleMaps ; Ulakhan-Chistai Mt. Range, Ignatov & Ignatova 18-2123 ( MHA9028887 About MHA ) ; Orulgan Mt. Range , Tumara, Ignatov 11-4468 ( MW9055466 ) ; Oimyakon Distr., Mus-Khaya Mt., Ignatov & Ignatova 11-3022 ( MW9055467 ) ; Ust-Maya Distr., Allakh-Yun , Ignatov 00-878 ( MHA9041471 About MHA ) ; Nature Park “Lena Pillars”, Ignatov & Ignatova 16-330 ( MW9077452 ) ; Amurskaya Province: Zeya Nature Reserve, Dudov & Kotelnikova 2014_ Br _9139 ( MW9079826 ) ; Norsky Nature Reserve , 6.VII.2010, Bezgodov 228 ( MHA9041681 About MHA ) ; Khabarovsk Territory: Bureinsky Nature Reserve , 8.VIII.1992 Borisov s.n. ( MW9055482 ) ; Botchi State Reserve, Ignatov & Ignatova 13- 60 ( MW9055474 ) ; Primorsky Territory: Shkotovo Distr., Pidan Mt. , Ignatov & Ignatova 06-2111 ( MW9055479 ) ; Chuguevka Distr., Berezovy Creek , Ignatov 07-232 ( MW9055477 ) ; Terney Distr., Isakov Creek , Ignatov & al 13-1820 ( MW9055029 ) ; Kamchatsky Territory: Kamchatka Peninsula, Elovka River , 29.VIII.2003, Czernyadjeva 115 ( MHA9041706 About MHA ) ; Sakhalinskaya Province: Sakhalin Island, Nogliki Distr. , Gortachie Klyuchi station , Pisarenko op03391 ( MHA9041462 About MHA ) .

Localities confirmed by J. Wynns (pers. corr. May 2019): * GREENLAND : K. Holmen & G. Mogensen 71-1916, sub P. laetum ; Kangerdluatslaq, Arveprinsens Ejland [ W5 ], 69°52’N, 50°47’W, 12 Aug 1971 GoogleMaps , C; K. Holmen & G. Mogensen 71- 2531, Ivnaq, Arveprinsens Ejland, 69°48’N, 51°14’W, 14 Aug 1971, sub P. piliferum GoogleMaps , C; K. Holmen & G. Mogensen 71-2532, idem, sub P. laetum , C; K. Holmen & G. Mogensen 71-2538, idem , C; K. Holmen & G. Mogensen 71-2552, idem, sub P. denticulatum , C; J. Lewinsky 73-948, Kilaersarfik , Ameragdla, Godthĺb distr. [ W3 ], 64°15’N, 50°12’W, 1 Aug 1973, sub P. laetum GoogleMaps , C. NORWAY: Musci Spetsbergenses Exsic. 122 p.p., Parrys I, Spitsbergen [Svalbard], 1868 , UC no. 1752324. SWE- DEN: T. Westergren 204, Kvikkjokk, Lapponia Lulensis, original specimen of P. westergrenii, HBG .

Plagiothecium berggrenianum Frisvoll, Lindbergia

7(2): 96–98, f. 2. 1981[1982]. Fig. 11 View Fig .

Description. Plants medium-sized to large, in loose lustrous mats, often growing by individual shoots in tufts

of other mosses or hanging down a cliff surface. Stems 1–3 cm long, poorly branched, foliage julaceous. Leaves appressed, directed upwards, symmetric, strongly concave (in slides plicate and crumpled), 1.4–1.6 × 0.8–0.9 mm, broadly ovate, cucullate at apex, abruptly narrowed to a hooked, reflexed apiculus, longly decurrent, cells of decurrencies in 2–4 rows, rectangular, sometimes round close to leaf base; leaf margins entire or minutely serrulate shortly below apex, more or less widely recurved almost throughout; costa short and double, occasionally extending beyond midleaf; laminal cells 75–130 × 7–9 µm, thick-walled. Gemmae of 3–4 short rectangular cells, occasionally present. Autoicous. Setae 2–2.2 mm long; capsules straight and erect or slightly curved and more or less inclined, 1–1.2 mm long. Exostome teeth ca. 450 µm long; cross-striolate below, slightly papillose in upper half; endostome basal membrane ca. 180 µm long, segments slightly longer than exostome teeth; cilia 2, up to as long as segments, nodose to appendiculate. Spores 15–21 µm.

Distribution and ecology. This northern species is not rare in permafrost areas of Asian Russia (Taimyr Peninsula and adjacent areas, Yakutia, Chukotka, Magadan Province); it extends southward up to ca. 61°N (Ust-Maya District of Yakutia). It is also known from islands of the Arctic Ocean, Svalbard and Franz Josef Land. In North America it is confined to the northernmost areas, including Greenland, Alaska and NW Territories. Grows on wet cliffs and rocks along water courses, in shady niches under boulders, on moist turf and humus in shady places, in tundra and Sphagnum bogs, occasionally on rotten wood. Forms pure mats or grows as solitary shoots in tufts of other mosses.

Differentiation. Plagiothecium berggrenianum is a conspicuous plant due to a combination of such morphological characters as large size of plants and appressed, symmetrical, ovate, strongly concave leaves with distinctly recurved margins and hook-shaped apiculus. It makes unlikely its confusing with any species of the P. laetum complex (see, however, discussion under P. svalbardense ). Sporophytes and gametangia of P. berggrenianum were unknown from Svalbard and not described in the protologue. Later sporophytes of this species were found in the Russian Arctic (West Siberia, Yamal) and described by Ukrainskaya (1996), who mentioned a dioicous sexual condition, erect or slightly inclined capsules, absence of cilia and large size of spores (15–17 µm). Sporophytes of P. berggrenianum were also illustrated by Ignatov et al. (2001), who found this species in Ust-Maya District of Yakutia (one of southernmost localities). Cilia were drawn as short, and sexual condition was described as autoicous (at least some shoots with both antheridia and archegonia were observed). Since that time more collections of P. berggrenianum were made in Asian Russia. According to our observations, an autoicous sexual condition is confirmed; cilia of endostome may be almost as long as segments, nodose to almost appendiculate; and spores are sometimes even larger, 15–21 µm.

Selected specimens examined: ASIAN RUSSIA: Yamalo- Nenetsky Autonomous Distr. : Yamburg 25.VII.2014, Bezgodov 239 ( PPU6896 View Materials ) ; Yunto Lake , 2.VIII.1993, Czernyadjeva 13 ( LE) ; Gydan Peninsula , 11.VII.1991, Czernyadjeva 24 ( LE) ; Ngaranato Lake , 19.VIII.1992, Czernyadjeva 21 ( LE) ; middle course of Sebayakha River , 22.VII.1992, Czernyadjeva s.n. ( LE) ; middle course of Khabeyakha River , 31.VII.1981, Rebristaya 38 ( LE) ; Krasnoyarsk Territory: Byrranga Mts. , Fedosov Plt 7 ( MW) ; Medusa Bay , 6.VII.2002, Varlygina s.n. ( MW9054793 ) ; Ledyanaya Bay of Taimyrskoe Lake , Fedosov P87 ( MW9054797 ) ; Kotuikan River, Fedosov 11-607 ( MW9054787 ) ; Afanas’evskie Lakes, Fedosov 06-589 ( MW9054790 ) ; Ary-Mas biostation, Fedosov 07A-1-17 ( MW9054789 ) ; same place, 30.VII.1972, Norin s.n. ( LE) ; Ereechka River, Fedosov 13-3-0469 ( MW9054785 ) ; Republic of Sakha / Yakutia: Orulgan Mt. Range , Ignatov 11- 4182 ( MW9054800 ) ; Kyurbelyakh Creek, Ignatov & Ignatova 11-2178 ( MW9054802 ) ; Oimyakon Distr., Mus-Khaya Mt., Ignatov & Ivanov 11-3582 ( MW9054804 ) ; Ust-Nera Settl., Tas- Kystabyt Range , Ignatov & Ignatova 15-1222 ( MW9054799 ) ; Nizhnekolymsk Distr. , 8.IX.1972, Stepanova s.n. ( MW9054805 ) ; Lower course of Indigirka River, Malaya Ercha Creek , 2.VIII.1974, Afonina s.n. ( LE) ; Anabar Distr.: Anabar River basin, Andreev 8244/2 ( SASY) ; Saskylakh Settl. , Andreev 8248/2 ( SASY) ; upper course of Kele River , Andreev 8246/2 ( SASY) ; Verkhoyansky Distr. , Elgetsk, Isakova 8250/2 ( SASY) ; Chukotsky Autonomous District: Providensky Distr., Arakamchechem Island , Afonina A-35 ( LE) ; St. Laurence Bay , 25.VII.1934, Gorodkov s.n. ( LE) ; Place of confluence of Chegitun and Khesmymken Rivers , 24.VIII.1982, Katenin & Popov s.n. ( LE) ; Karvakyanskaya Creek , 27.VII.1982, Afonina s.n. ( LE) ; Egvekinot , 16.VIII.1985, Afonina s.n. ( LE) ; Magadan Province: Okhotskoe Sea coast, Kamenny Range, Ermolenko op06803 ( NSK2006803 About NSK ) ; Kamchatsky Territory: Sobolevsky Distr., Pravy Kikhchik River basin, 23.VII.2004, Czernyadjeva 15 ( LE) .

Localities confirmed by J. Wynns (pers. corr. May 2019): * CANADA: NUNAVUT: Resolute Bay, Cornwallis Island , 74°41’N, 94°50’W, 10 m, 14 July 1990, Mogensen 90-306 GoogleMaps , C. GREENLAND: Egedesminde, Tupilak Island [ W4 ], 68°42’N, 52°55’W, 30 June 1956, sub P. laetum, Holmen 15554 GoogleMaps , C. USA: ALASKA: vicinity of Point Barrow , SE of Laboratory, 71°40’N, 156°38’W, 2–3 m, 18 June 1973, Steere et al. 73-1 GoogleMaps , NY no. 159489; between National Arctic Research Laboratory and gas well, idem, 19 June 1973, Steere et al. 73-2 GoogleMaps , NY no. 159491; Meade River Post Office ( Coal Mine ), 70°28’N, 157°25’W, ca. 30 m, 12–15 July 1973, Steere et al. 73-372 GoogleMaps , NY no. 159490.