Grimmia beringiensis Ignatova & Ignatov, 2016

Grimmia beringiensis Ignatova & Ignatov View in CoL , sp. nov.

Figs. 3 View Fig , 4 View Fig .

Similar to Grimmia jacutica , differs in appressed leaves with straight vs. recurved hair-points, costa (2–) 3–4-layered vs. 2-layered in transverse section and growing on soil among rocks in tundras vs. on rocks.

Type: Russia, south-east of Chukotka Peninsula, northern shore of Senyavin Strait near Yanrakynnot Settlement , rocky calcareous tundra with patchy Dryas and lichens, 23.VII.1976, Afonina s.n. (Holotype MW, Isotypes LE, MHA) .

Plants medium-sized to large, growing in extensive, dense, but easily separating cushions, yellowish-green at tips of shoots, brownish below, dull. Stems 2–8 cm, ascending to straight, sparsely branching, densely foliate, without central strand. Leaves appressed when dry, straight or slightly twisted around

Species G. jacutica G. beringiensis G. leibergii G. arcuatifolia G. decipiens G. lisae

leaf lamina length, mm 2–2.5 2–3

hair-point length, mm, 0–0.5 0–0.8 decurrency decurrent decurrent and serration fine, distant fine, distant

costa width at base, µm 60–85 50–75

number of cell

layers in costa:

distal 2 2–3 median 2 3 basal 2 3–4

cell wall thickness strong strong

cell size, µm:

distal, width 7–12 8–13

distal, length 9–25 13–25 median, width 8.5–12 9–13 median, length 12–30 18–33

basal juxtacostal thick, thick,

cell walls porose porose

basal marginal

transverse cell walls thick thick

sexual condition dioicous dioicous 2–3.1 3-3.5 2.5–3 1.5–2

0.45–1.1 0–0.45 0.5–1.5 0–0.5 decurrent not decurrent decurrent decurrent fine, distant sharp, distant strong, dense sharp, dense

80–100 130–175 60–70 50–75

2 3 2 3

3 3–5 2 3(–4) 3–4 4–5 2 3(–4)

median median median median

5.5–8.5 7–9.5 9–13 5–7

7–15 6–12 10–14 4–9.5 7–10.5 7–11 9–12 5–8.5

9–20 7.5–15(–20) 15–25 9–16

thick, thick, thick, thin, porose porose porose not porose

thick thin thick thick

dioicous dioicous autoicous dioicous

sporophyte frequency rare unkmown frequent rare frequent rare

the stem, erecto-patent when wet, lamina 2–3 mm long, 0.45–0.6 mm wide, narrowly lanceolate; hair-points 0–0.6(–0.8) mm long, with very short distant spinulae to almost smooth, short to long decurrent; costa 50– 75 µm wide at leaf base, moderately projecting dorsally, reniform in transverse section, with 3–6 cells exposed on ventral surface, 2–3-layered distally, 3– layered in mid-leaf and 3–4-layered at base; margin recurved in proximal 2/3–3/4 on one side of leaf and shorter recurved on the other side, plane and slightly uneven distally; lamina smooth, unistratose except one bistratose marginal or submarginal row of cells; distal lamina cells rectangular, (12–)15–25(–28) µm long and (8–) 10–12(–13) µm wide, thick-walled, walls slightly sinuose; median lamina cells elongate-rectangular, (18–)21–30(–35) µm long and 9–11(–13) µm wide, with strongly thickened and strongly sinuose longitudinal walls and thin transverse walls; basal juxtacostal cells linear, 12–13 µm wide and 30–50(–70) µm long, thick-walled and porose, basal marginal cells short rectangular, with thickened transverse walls, occasionally pellucide. Sexual condition dioicous, gametangia lateral. Sporophytes unknown.

Specimens examined: RUSSIA: Chukotka: Yanrakynnot Settlement surroundings, 20.VII.1976, Afonina s.n. ( LE, MW) ; Ushkligran Settlement outskirts, 6.VII.1970, Afonina s.n. ( LE, MW) ; NW shore of Penkigney Bay near Peszovaya Creek mouth, 11.VII.1978, Afonina s.n. ( LE, MW) .

Distribution and ecology. The species was collected in several rather close localities in south-eastern Chukotka. It grows at low altitudes not far from sea coast, on

soil in rocky tundras in an area with calcareous bedrocks, along patchy Dryas communities with extensive moss and lichen cover; it was also once collected in Alnus fruticosa stands on calcareous slopes of a hill.

Differentiation. Leaves of G. beringiense are slightly longer than those of G. jacutica , with lamina length up to 3 mm vs. to 2.5 mm. Its hair-point length and decurrency, and lamina areolation are very similar or practically identical with G. jacutica ( Fig. 4 View Fig , see also illustrations in Ignatova et al., 2003). However, these two species can be recognized with a hand-lens or under stereomicroscope by their different leaf arrangement and hair-point orientation: leaves are straight, occasionally only slightly twisted and with straight hair-points in S. beringiense , while in G. jacutica laeves are often secund and usually have hair-points recurved at right angle, resembling Racomitrium laetum in this character. Furthermore, Grimmia jacutica grows mostly on rocks, often on and between boulders of rock-fields, whereas G. beringiensis was collected on soil in tundras. Plants of G. jacutica are in most cases yellowish-olivaceous in a considerable distal portion, whereas plants of G. beringiensis have only uppermost leaves yellowish-green and with most part of the shoots brown. Among microscopic characters, costa transverse section alone is important, being always bistratose throughout in G. jacutica and 3–4-stratose in G. beringiensis at least at leaf base.

Grimmia beringiensis differs from G. leibergii in considerably larger laminal cells with much thicker longitudinal walls ( Table 1, Figs. 4 View Fig –5). Costa of G. leibergii is 3–4-stratose in transverse section, like in G. beringiensis , but it is much wider in the former species, 80–100 µm vs. 50–75 µm, with greater number of cells on ventral surface and stronger differentiated ventral surface cells ( Figs. 4 View Fig –5). In addition, falcate-secund leaves, the plants usually fertile, and the dark-green colored plants, make G. leibergii contrastingly different from the brown plants with straight leaves of G. beringiensis , which sporophytes are still unknown.

Grimmia attenuata superficially resembles G. beringiensis in shoots with straight and appressed leaves and straight hair-points, but these two species have strikingly different lamina areolation (see Figs. 4 View Fig –5 and Table 1). The exceedingly strong costa of G. attenuata , very wide (130–175 µm at base) and 3–5-stratose, the non-decurrent hair-ponts, and the thin-walled basal marginal cells, are the features distinguishing it from all three other species of this group.

The differences between G. beringiensis and G. decipiens include finely and distantly vs. sharply and densely serrate hair-points, straight vs. falcate leaves, 3-stratose vs. 2-stratose costa and strongly vs. moderately thickened cell walls. Grimmia lisae differs from G. beringiensis in the smaller size of plants and leaves, strongly recurved vs. erecto-patent leaves in wet condition, and basal juxtacostal cells with thin and non porose walls vs. thick and strongly porose walls. Both G. decipiens and G. lisae were only recently found in Russia (Doroshina et al., 2015; Bezgodov et al., 2016), and each of them is known from a single locality at the Black Sea coastal area in the West Caucasus.