Gymnomitrion faurianum (Steph.) Horik., Acta Phytotaxonomica et Geobotanica 13: 212. 1943

Bakalin, Vadim, Choi, Seung Se & Park, Seung Jin, 2021, Revision of Gymnomitriaceae (Marchantiophyta) in the Korean Peninsula, PhytoKeys 176, pp. 77-110 : 77

Gymnomitrion faurianum (Steph.) Horik., Acta Phytotaxonomica et Geobotanica 13: 212. 1943 Figure 9

Acolea fauriana Basionym. Acolea fauriana Steph. Species Hepaticarum 2: 8. 1901

Type.

Japan. “Tidesan” 29 August, 1898, Faurie 212 (lectotype (designated here) G [00067200/15025!])

Description.

Plants in loose mats, more or less soft, leaved part of shoot distinctly clavate, from rhizomatous base, dorsiventrally compressed, whitish to whitish green and pale brownish in general aspect, due to discolored leaf margins that gives expression of white pigmentation, although middle part of leaves maybe greenish to brownish green, 250.0-800.0 μm wide (large plants to 1000.0 μm wide) and 5.0-15.0 mm long. Rhizoids virtually absent to sparse in leaved shoots, but rather common in rhizomatous base and geotropic leafless stolons, soft, colorless, in indistinct obliquely spreading fascicles, rarely with admixture of solitary purple in color and rigid rhizoids. Stem in leaved part branched as subfloral innovations, while in rhizomatous base freely and variously branched, leafless geotropic stolons infrequent, originated mostly near base of leaved part of shoot; cross section not differentiated into distinct layers, nearly orbicular to slightly transversely elliptic, 140.0-160.0 μm high and 170.0-190.0 μm long; outer cells slightly larger than inner, 20.0-30.0 μm along margin with walls thick (but external wall thinner), trigones moderate in size, concave; inner cells irregular in shape, with flexuous thickened walls, 15.0-23.0 μm in diameter, trigones moderate in size, concave. Leaves densely imbricate, enclosed one to another, obliquely spreading, transversely oriented, not sheathing in the base, ovate to obliquely ovate and widely triangular in shape, 350.0-700.0 μm long and 400.0-650.0 μm wide, divided by V-shaped sinus descending to 1/7 (smaller plants from drier habitats) - 1/6-1/5 of leaf length into two equal to subequal triangular to loosely gibbous lobes with acute to obtuse apes and distinctly crenulate margins. Cells in the midleaf subisodiametric to rectangular and irregularly oblong, 17.0-30.0 × 17.0-23.0 μm, thin-walled, with moderate to large, convex trigones, cuticle smooth; cells along margin 12.0-18.0 μm, thick- to merely thin-walled, with thinner external wall, discolored in 1-5 cells rows almost to the leaf base, with trigones moderate to small in size, concave, cuticle sharply verruculose; cells in lobe middle 15.0-30.0 × 12.0-(18.0)20.0 μm, walls thin to thickened, trigones varying from moderate to small and from concave to bulging (if trigones become bulging cell walls become thinner), cuticle verruculose to smooth. Dioicous. Androecia intercalary. Perianth and perigynium absent, bracts similar to leaves, but larger, more deeply divided (up 15-1/4 of the length), with somewhat diverging and spreading, rarely erose-dentate lobes.

Ecology.

Acidophilic mesophyte. The species occupies mesic to moist (rarely wet) cliffs in open places, and rarely occurs in partly shaded habitats, producing thinner forms with not densely appressed leaves. In drier habitats, it is commonly associated with Gymnomitrion parvitextum , dwarf forms of Sphenolobus saxicola , saxicolous modifications of Anastrophyllum michauxii , in more wet habitats it may be mixed with Marsupella pseudofunckii and Protolophozia debiliformis .

Distribution.

East Asian oro-boreal species widely distributed in northern to middle Japan (although a rarity as far as Yakushima Island), abundant in southern Kurils. Within the Asian mainland, known from Sikhote-Alin mountain system, stretching to South Korea until Jeju-do. Likely to be found in North-East China (at least in Changbai Mountain). Previous reports of Gymnomitrion concinnatum (Lightf.) Corda from Yanggang-do and Pyeongannam-do ( Kim and Hwang 1991) likely belong to this taxon.

Specimens examined.

Gangwon-do: Mt. Seorak , 38°06'35.7"N, 128°25'33.7"E, 1449 m, 21 Sep 2009, S.S. Choi 5148, 5148-2 (JNU), Mt. Seorak , 38°07'09.4"N, 128°27'54.8"E, 1710 m, 21 Sep 2009, S.S. Choi 5206 (JNU), Mt. Seorak , 38°08'02.8"N, 128°28'03.6"E, 908 m, 12 Oct 2010, S.S. Choi 8378, 8381, 8384 (JNU), Mt. Seorak , 38°06'36.3"N, 128°25'33.6"E, 1452 m, 13 Oct 2010, S.S. Choi 8502 (JNU), Mt. Seorak , 38°07'08.9"N, 128°27'55.4"E, 1718 m, 13 Oct 2010, S.S. Choi 8557 (JNU); Jeju-do: Mt. Halla , 33°21'45.3"N, 126° 32'08.9"E, 1916 m, 8 Aug 2010, S.S. Choi 7759 (JNU), Mt. Halla , 33°21'45.3"N, 126°32'08.9"E, 1916 m, 8 Aug 2010, S.S. Choi 7765a (JNU), Mt. Halla , S.S. Choi 120372 (JNU), Mt. Halla, 33°21'51.0"N, 126°31'42.9"E, 1814 m, 7 Sep 2012, S.S. Choi 120827 (JNU), Mt. Halla, 33°21'42.1"N, 126°32'02.8"E, 1861 m, 21 Sep 2012, S.S. Choi 120890, 120894, 120907, 120909, 120924, 120925, 120936, 120937, 120938 (JNU) .

Comment.

The whitish plant coloration, distichous leaf arrangement, and distinctly bilobed leaves easily help in recognizing G. faurianum . The difference from G. corallioides is the presence of persistent cells along the leaf margin and verrucose cuticle in the leaf lobes, as was noted in the key. Moreover, we consider the occurrence of G. corallioides in Korea unlikely. Another problem is the differentiation of G. faurianum from G. concinnatum , which shares the papillose cuticle in the leaf apex and stout cell walls in the leaf margins. However, G. faurianum differs from G. concinnatum in strongly distichous leaf arrangement, dorsiventrally compressed shoots and whitish coloration (although in Europe G. concinnatum may be sometimes whitish green and pure green, such modifications were never observed in East Asia) - the features rather resembling G. corallioides , which were the reasons for the misidentifications of G. faurianum for both G. concinnatum and G. corallioides , as discussed by Bakalin (2016).

Figures

Figure 9. Gymnomitrion faurianum (Steph.) Horik. A gynoecium longitudinal section B plant habit C, D leaves E stem cross section (fragment) F midleaf cells G cells in leaf lobe apex. Scale bars: a 1 mm (A-D); b 100 µm (E-G).