Gymnomitrion commutatum (Limpr.) Schiffn., Magyar Bot. Lapok 13: 304, 1914 [1915].

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

Gymnomitrion commutatum (Limpr.) Schiffn., Magyar Bot. Lapok 13: 304, 1914 [1915].

Marsupella commutata (Limpr.) Bernet, Cat. Hép. Suisse: 29, 1888

Sarcocyphos commutatus Basionym. Sarcocyphos commutatus Limpr., Jahresber. Schles. Ges. Vaterl. Cult. 57: 314, 1879 [1880].

Type.

Austria. Tirol, Montefuner Tal , 2300 m, 1868, leg. Jack, (lectotype BP (not seen)) .

Description.

Plants in loose patches, rigid, slightly glistening when dry, hardly soaking, blackish brown, without red or purple pigmentation, 450.0-700.0 μm wide and 5.0-15.0 mm long. Rhizoids nearly absent, with the exception of ventral stolons, where common (sometimes dense), colorless or with admixture of solitary deep purple. Stem brownish to whitish (commonly whitish in geotropic stolons), branching lateral or ventral, rather common as subfloral innovations, also as ventral stolons with scale-like leaves; transversely elliptic in cross section, 120.0-140.0 μm high and 130.0-150.0 μm wide, composed by rather uniform cells, outer layer cells 12.0-20.0 μm along margin, slightly larger than inner cells, with brownish and unequally thickened walls and large (sometimes confluent) concave trigones; inner cells 10.0-18.0 μm, walls unequally thickened, colorless, trigones large, triangular to convex. Leaves imbricate, enclosed one to another, concave-canaliculate to concave and spoon-shaped, transversely inserted, sheathing the stem, loosely obliquely spreading and transversely oriented, sometimes secund dorsally, elliptic to loosely widely ovate or obovate or nearly rectangular, 320.0-500.0 μm long and 300.0-450.0 μm wide, margin recurved to plane in upper part of the leaf, divided by V-shaped sinus, with commonly recurved basal part of the sinus, descending to 1/4-1/3 of leaf length, into two equal to subequal lobes, lobes triangular to gibbous with obtuse to acute, rectangular or even rounded apex. Cells in midleaf 8.0-20.0(-23.0) × 8.0-17.0 μm, walls thin, trigones large, bulging, cuticle smooth to finely verrucose; cells along margin 6.0-11.0 μm, with thin to thickened walls, trigones large, bulging or convex, sometimes confluent, in robust phases external wall protruding, the margin then crenulate, cuticle smooth to verrucose; cells in lobe middle 7.0-13.0 × 7.0-12.0 μm, thin-walled, with large bulging or quadrate and confluent trigones (gives expression of chessboard), cuticle smooth to verrucose.

Ecology.

Acidophilic meso-xerophyte, the species occupies more or less dry substrata in exposed to (rarely) partly shaded areas. In the study area was intermixed with Gymnomitrion noguchianum .

Distribution.

Gymnomitrion commutatum was described based on plants from Austria. Váňa et al. (2010: 20) gave its distribution as "Northern Europe, Middle Europe, Southwestern Europe, Southeastern Europe, Siberia, Russian Far East, China, Eastern Asia, Indian Subcontinent, Malesia, Subarctic America, Western Canada, Northwestern USA". Many of the Asian records may belong to other taxa, for instance, Gymnomitrion parvitextum , discussed below ( Mamontov et al. 2018). In turn G. commutatum may possess disjunctive arctic-alpine distribution. Within Pacific Asia G. commutatum is known from the Russian Far East, Japan, and likely may be found in China. This species is only found in the Halla-san crater rim. It is noteworthy that this species is known from Jeju-do, whereas the morphologically similar G. parvitextum (see below) is not found there, but is quite common in other provinces of Korea.

Specimens examined.

Jeju-do: Mt. Halla , 33°21'51.0"N, 126°31'42.9"E, 1814 m, 7 Sep 2012, S.S. Choi 120826 (JNU), 33°21'42.1"N, 126°32'02.8"E, 1861 m, 21 Sep 2012, S.S. Choi 120924 (JNU), Mansedongsan valley, 33°21'59.6"N, 126°30'40.3"E, 1591 m, 6 Sep 2012, S.S. Choi 120834 (JNU) .

Comment.

The species is very similar to G. parvitextum , and the distinctions between the two taxa are described below.