Gymnomitrion rubidum (Mitt.) Váňa, Crand.-Stotl. et Stotler

Bakalin, Vadim, Vilnet, Anna, Long, David, Klimova, Ksenia, Maltseva, Yulia, Nguyen, Van Sinh & Ma, Wen Zhang, 2022, On two species of Gymnomitrion (Gymnomitriaceae, Marchantiophyta) in the Eastern Sino-Himalaya, Phytotaxa 533 (2), pp. 117-136 : 128

Gymnomitrion rubidum (Mitt.) Váňa, Crand.-Stotl. et Stotler , Syst. Bot. 40 (1): 39, 2015 ( Shaw et al. 2015).

Bas.: Jungermannia rubida Mitt.

( JE04000310 !, isolectotype) .

subsp. rubidum (haplotype 1).

Description: Plants brown-green to rusty green, yellowish brownish and almost rusty-brown, without any traces of purple or red coloration, glistening, with a distinct black tinge when dry; forming loose pure patches (sometimes with scarce admixture of mosses), rigid,; 1.0–2.0 mm wide and 15–25 mm long; erect to ascending. Rhizoids virtually absent in normally leaved shoots, but rather sparse in geotropic stolons, brownish to colorless, rarely rhizoids purple in origin area near ventral side of the branch. Stem freely ventrally branched in the basal part of the shoot, in apical parts only as subfloral innovations; stem cross section transversely elliptic, ca. 125–170 × 170–210 μm, with well defined cortex of 3–4 layers of cells, cells 7–10 μm in diameter or shortly oblong, thick-walled; inner cells with walls becoming thinner, 20–28 μm in diameter, with large concave trigones, moderate in size. Leaves concave-canaliculate, sheathing the stem near base, transversely inserted, barely or shortly decurrent on both sides, obliquely to almost erect spreading, strongly turned ventrally, divided by U-shaped to widely V-shaped sinus descending for 1/6–1/5 of leaf length into 2 short, unequal (ventral smaller) acute lobes terminated by 1–3 superposed cells; commonly lacerate when flattened in the slide; then rounded to ovate (longer than wide) and widely ovate (wider than long), 800–1300 × 800–1100 μm. Midleaf cells oblong, 10–25 × 7–18 μm, thick-walled, with large, convex (sometimes indistinctly Y-shaped) trigones; cells near leaf base, 50–70 μm long, with unequally thickened walls, with commonly visible middle lamella, with indistinct ‘vitta’ gradually transforming into surrounding cells; cells along margin 7–10 μm, with thick external wall, other walls thick, trigones large, mostly concave; cells in middle part of leaf lobe 7–9 μm in diameter to 10–20 × 7–10 μm, thick-walled, trigones large, convex, commonly confluent, cuticle smooth throughout. Dioicous. Androecia with 2–3 pairs of bracts inflated near base, different generations separated by 8–10 pairs of sterile leaves, 2-androus, body obovate, 75–83 × 62–68 μm, stalk ca. 110 μm long, biseriate. Female perichaetium with 2 pairs of bracts—outer larger, to 1.0– 1.3 mm long and inner smaller; perianth and perigynium absent. Capsule shortly exerted from perichaetium, nearly spherical, 0.4–0.6 mm in diameter, outer capsule wall cells shortly rectangular, 15–25 × 15–20 μm, with nodulose (mostly confluent) thickenings, by 2–3 in every second vertical wall (one of two vertical walls has the thickenings, remaining wall is thickening-free). Seta short, 0.5–0.9 mm long. Spores brown, very finely papillose, 10–12 μm in diameter. Elaters 3-spiral, 125–175 μm long and 7–9 μm wide in centre (then gradually narrowing to the ends), ends not homogenous ( Figs 7 , 8 , 9 ).

Figures

FIGURE 7. Gymnomitrion rubidum (Mitt.) Váňa, Crand.-Stotl. et Stotler subsp. rubidum: A—plant habit, fragment, ventral view; B— plant habit, fragment, dorsal view; C—plant habit, fragment, lateral view; D–L—leaves; M—stem cross-section; N—midleaf cells; O— cells in leaf lobe apex; P—leaf margin cells; Q—cells in leaf base. Scales: a—1 mm for A–C; b—1 mm for D–L; c—100 µm for M–Q. All from V-19-6-18 (VBGI).

FIGURE 8. Gymnomitrion rubidum (Mitt.) Váňa, Crand.-Stotl. et Stotler subsp. rubidum: A—plant habit in dry condition; B—leaf; C—stem cross-section; D—cells in leaf base; E—antheridia. Scales: for A—5 mm; for B—1 mm; for C, D—100 µm; for E—200 µm. A, B, D from isolectotype (JE 04000310), C, E from V-19-6-18 (VBGI).

FIGURE 9. Gymnomitrion rubidum (Mitt.) Váňa, Crand.-Stotl. et Stotler subsp. rubidum: A—plant habit, fragment, lateral view; B— plant habit with sporogonium, fragment, lateral view. Scales: for A—1 mm; for B—1 mm. All from isolectotype (JE 04000310).