Dicranum baicalense Tubanova, 2022

Tubanova, D. Ya. & Dugarova, O. D., 2022, Dicranum baicalense (Dicranaceae, Bryophyta), a new species from Russia, Arctoa 31 (2), pp. 145-154 : 147-149

Dicranum baicalense Tubanova , sp. nov. Figs. 2–3 .

Type. Russian Federation, Republic of Buryatia, Kyakhta District, vicinity of Naushki Settlement , “Botyiskaya Yama” Gully , Mel’nichnaya Stream , 50°23’34.3"N, 106°11’37.9"E, 685 alt., grassy willow and birch thick- et, on soil and rotten wood, 18.VII.2010, coll. D.Ya. Tubanova # Kyakh-06/1042 [holotype UUH] .

Diagnosis: Dicranum baicalense is similar to D. scoparium Hedw. in habit of plants, sharing secund leaves with elongate, porose distal laminal cells and ridges on the dorsal side of costae in distal leaf portions. It differs from this species in having straight, homomallous vs. falcate-secund leaves; costae with 2(3) vs. (3)4 ridges on dorsal side; and longer distal laminal cells: 70–100 µm long vs. 25–50 µm long. The differences of D. baicalense from D. japonicum Mitt. , which also has 2(3) ridges on dorsal side of costa, include shorter leaves: 5.5–7.5 mm vs. 8–9(–11) mm long; and shorter laminal cells: 70– 100 µm long vs. 80–110 µm long. Dicranum baicalense is also similar to D. orthophyllum Broth. in having straight leaves and costae with 2(3) ridges, but the latter species has erect to appressed, not homomallous leaves and straight capsules.

Etymology. The species epithed ‘baicalense’ refers to the vicinity of the Lake Baikal, where from the first collection of the species originates.

Description. Plants medium-sized, in loose tufts, glossy, yellowish to light green. Stems 6–8 cm, more or less densely foliate, moderately to densely tomentose, tomentum whitish in upper part of stems and brownish below. Leaves homomallous, straight-secund to slightly flexuose-secund when dry, straight-secund when wet, lanceolate, (5–)5.5–7.5× 0.6–0.9 mm, from lanceolate or ovate-lanceolate base gradually long acuminate, concave proximally, keeled or slightly canaliculate distally; margins plane or slightly incurved, serrate distally, unistratose; costa 1/11–1/9 of leaf width at base, percurrent or ending below apex, in upper part on abaxial surface with 2–3 serrate ridges 1–2 cells high, in transverse sections with one row of guide cells, two stereid bands, adaxial and abaxial epidermal layers of cells not differentiated; lamina 1-stratose, cells irregularly mammillose, often oblique in leaf transverse sections; distal laminal cells elongate rectangular to linear, (55–)70–105(–142)×(9–) 10–12.5(–14.5) µm, moderately thick-walled, porose; basal laminal cells (69–)82–124(–159)×(9–)11–15(–18) µm, moderately thick-walled, porose; alar cells welldifferentiated, 2-stratose, brownish, not reaching the costa. Phyllodioicous. Male plants dwarfed, on rhizoidal tomentum of female plants. Inner perichaetial leaves abruptly long-acuminate, convolute-sheathing. Setae 2.5–3 cm. Capsules cylindrical, arcuate, urns 2.5 mm long, brown, smooth when dry. Annuli not seen. Operculum with long, straight beak. Spores 13–24 µm, papillose.

Distribution and habitats. Dicranum baicalense is known from southern Siberia (Republic of Buryatia and Zabaikalsky Territory) and the southern part of the Russian Far East (Amur Province and Primorsky Territory). It grows on rotten wood, bases of trees, soil and litter in various types of forests. It was also collected from granite outcrops covered with humus.

Distinctions. Dicranum baicalense is similar to the species of the section Dicranum (Hoggets et al., 2020) in having leaves with elongate, porose distal cells and costa with dorsal lamellae (ridges). The comparison with species from this section occurring in Russia and nearby areas is presented in Table 1. Our observation on the studied material is supplemented by published data (Savicz-Ljubitzkaja & Smirnova, 1970; Gao et al., 1999; Ignatov & Ignatova, 2003; Hedenäs & Bisang, 2004; Ireland, 2007; Lang & Stech, 2014; Lüth, 2002; Noguchi & Iwatsuki, 1987; Otnyukova, 2001; Price & Maier, 2013; Sérgio at al., 1995; Tubanova & Afonina, 2016).

Dicranum baicalense looks rather similar to D. scoparium in plant size and secund leaves, although in the latter species leaves are usually falcate, whereas in D. baicalense they are almost straight and homomallous. Distal laminal cells in Siberian populations of D. scoparium are 25–50(–60) µm long vs. 70–100 µm long in D. baicalense . The leaf transverse sections of D. scoparium show (3)4 lamellae or large cells on the dorsal side of costa, while in D. baicalense such cells or lamellae are two, rarely three.

Dicranum baicalense is similar to D. orthophyllum Broth. in having straight leaves; however, in D. baicalense leaves are always homomallous, while in D. orthophyllum they are erectopatent. Distal laminal cells are longer in D. orthophyllum : 90–140 µm vs. 70–100 µm. There is also a distinction in sporophyte characters between these species: capsules of D. baicalense are arcuate, while they are straight in D. orthophyllum .

The differences between Dicranum baicalense and D. japonicum include homomallous vs. often spreading to all sides leaves; distal laminal cells 70–100 µm vs. 80–110 µm long; alar cells 2-layered vs. 2–4-layered; and capsules smooth vs. striate when dry.

Dicranum nipponense , which is fairly easy to recognize in nature, is distinguished by dark green color of plants; its leaves are quite short, mostly straight and more or less blunt. One of the main microscopic characteristics that separates it from the other species of this group is the presence of short cells above the alar cells, extending upwards along the leaf margins. Dicranum polysetum is recognized by spreading, transversely undulate leaves, and typically several sporophytes from perichaetium. These characters separate both these species from D. baicalense , which is characterized by yellowish-green color of plants; long, homomallous, not undulate leaves; and one sporophyte from perichaetium.

There are contradictory descriptions of morphology for Dicranum lorifolium , a species recently reported for the Russian moss flora ( Lang & Stech, 2014). Among other diagnostic characters, straight capsules are mentioned ( Mitten, 1859, p. 15), whereas in D. baicalense capsules are arcuate.

Additional specimens examined: RUSSIA: Republic of Buryatia: (1) Bichursky District, Malkhansky Ridge, vicinity of Maly Kunaley Village , Bol’shoy Kunaley Stream , E slope ~30°, 50°32’48.0"N, 107°47’39.1"E, 725 alt., sparse grass-birch forest, at the birch base, 23 August 2011, Tubanova Bi-1/1141 ( UUH); (2) Dzhidinsky District, Baikalsky Reserve, valley of Abiduy River , middle course, pine-birch mixed-grass forest with abies, on pine rotten wood, 27 July 1991, Kazanovsky 1721 ( IRK, UUH); (3) Kabansky District, Khamar-Daban Ridge, Levaya Mysovka River , Bushalay , 51°32’49.5"N, 105°50’23.8" Ĺ; 1227 alt., reforestation of fir with blueberries and mosses, on soil and rotten wood, 03 July 2013, Tubanova Ка-02/1312 ( UUH); (4) Okinsky District, Tunkinsky Ridge, Natural Park “Shumak”, left bank of Shumak River , vicinity of hot spring, 51°58’11.5"N, 101°52’03.0"E, 1507 alt., larchspruce cowberry-moss forest, on soil, 26 July 2016, Tubanova Tu-161115 ( UUH) with sporophytes; (5) Tunkinsky District, Tunkinsky Ridge, about 5 km to N from camp site ‘ Sukhoy Ruchey ”, 51.75935°N, 101.61678°E, 1072 alt., birch grass forest, on soil and rotten wood, 22 July 2016, Tubanova Тu- 160105, Тu-160106 ( UUH) with sporophytes; (6) same place, Tubanova Тu-160106 ( UUH) with sporophytes; (7) Tunkinsky District, about 10 km to the SW from Zhemchug Village, Khongor-Uul mineral source, 51°36’25.8"N, 102°21’50.0"E, 812 alt., mixed forest with grasses, on soil, 14 September 2017, Tubanova Tu 170109 ( UUH); (8) loc. cit., Tubanova Tu 170110 ( UUH); (9) same place, 51°35’45,0"N, 102°20’48,0"E, 857 alt., birchlarch forest with grasses, on soil, 14 September 2017 Tubanova Tu 170207 ( UUH); (10) same place, Tubanova Tu 170212 ( UUH); (11) same place, Tubanova Tu 170208 ( UUH); (12) Zakamensky District, Vicinity of Ust’ Burgaltay Village , 50.48767°N, 104.06935°E, 1075 alt., birch-grass-sedge forest, on soil, 10 August 2018, Anenkhonov Op. Zk-3/18 ( UUH) with the sporophytes. Zabaikal’skiy Territory: Kalarsky District, Yuzhno-Muysky Range, Koira Creek , 56°13’59.5"N, 115°52’59.5"E, 589-600 alt., mixed forest along creek, on deadwood. 07 August, Afonina 7912b ( LE, UUH) with sporophytes. Amur Province: (1) Selemdzhinsky District, Ust’-Norskaya Sopka , S slope of 306.5-elevation, 52°25’30"N, 129°55’30" E, 200 alt., granite outcrops, 18 July 2011, Bezgodov 261 ( MHA); (2) same place, on humus, 23 July 2011, Bezgodov 409 ( PPU, UUH); (3) same place, on soil, 20 July 2011, Bezgodov 357 ( PPU, UUH); (4) same place, on a humus-covered rock ledge, 20 July 2011, Bezgodov 286 ( PPU, UUH); (5) Selemdzhinsky District, “Norsky” Reserve, left bank of Selemdzha River , the channel Aleksandrovskaya , 52°25’N, 130°14’E, 220 alt., granite outcrops, on covered with humus rotten wood, 11 July 2011, Bezgodov 138 ( PPU, UUH); (6) same place, valley of Selemdzha River , 0.8–1 km from cordon “Dvadtzatikha”, 52°25’30"N, 130°12’E, 220 alt., fir forest with grasses, on the soil and litter, 10 July 2011, Bezgodov 89 ( PPU, UUH); (7) Selemdzhinsky District, right slope of Nora River valley, in the lower reaches, Mal’tzevskaya Sopka , 52°30’N, 129°49’E, 220 alt., granite outcrops, on the shady steep walls, 08 June 2011, Bezgodov 57 ( PPU, UUH) . Primorsky Territory (1) Partizansky District, Ol’khovaya Mountain , S slope, 43°19’37.4"N, 133°39’57.5"E, 1230 alt., dark coniferous forest with alder and maple, on soil, 22 September 2015 Tumurova Vl-833 ( UUH) with sporophytes; same place, Tumurova Vl-834 ( UUH) with sporophytes.

Figures

Fig. 2. Dicranum baicalense (from holotype): A: habit, wet; B–G: leaf transverse sections; H–I: leaves; J: plant with sporophyte, dry; K: upper laminal cells; L: basal laminal cells. Scale bars: 1 cm for A, J; 1 mm for H, I; 100 µm for B–G, K–L.

Fig. 3. Habit of Dicranum baicalense: A, from holotype; B, from Amur Province, Bezgodov 261, DNA 179; C, from Zabai- kal’skiy Territory, Afonina 7912b, DNA 178; D, from Primorskiy Ter- ritory, Tubanova Pr1508/02, DNA348; E, from Republic of Buryatia, Tubanova O1517/01, DNA426. .