Plants rigid to soft, variously colored. Rhizoids sparse to dense, mostly colorless, rarely purple. Stem with differentiation into scleroderm, hyaloderm and inner tissue or without differentiation (then mostly pachydermous in structure). Leaves shallowly emarginate to bilobed (not more than 2/5 of leaf length) into equal to unequal lobes. Underleaves absent (present in Nardia not treated here). Androecia intercalary, stalk biseriate. Perianth well developed to reduced or totally absent. Perigynium well developed to absent (and then perianth wanting or strongly reduced). Elaters with 2–4 spirals.

The above description is applicable to the Gymnomitriaceae taxa occurring in the Korean Peninsula.

Plants forming loose patches, commonly ascending or rarely creeping in habitats with strong insolation and incrusted by soil particles, deeply (deep green, brown-green, brown purple, blackish brown) to pale (yellowish, brownish, greenish and their combinations) colored, merely rigid, varying in size from 0.5 to 2.0 mm wide and 5.0–50.0 mm long. Rhizoids sporadic to solitary, although invariably present in ventral geotropic leafless stolons, colorless to grayish and soft-textured, or rarely and solitary purple and rigid. Stem with common ventral branching and rare lateral branches, with characteristic geotropic stolons present in the majority of taxa; in cross section mostly differentiated into three strata: hyaloderm, scleroderm and inner tissue. Leaves transversely or nearly so inserted, obliquely to erect spreading from sheathing or not sheathing base, concave to canaliculate and strongly conduplicate, divided by evident but not deep sinus into two equal to strongly unequal lobes with rounded to acute apices. Underleaves absent. Cells in the leaf in the most taxa pachydermous with large convex trigones, unequally thickened along margin and having smooth cuticle; oil-bodies few in number, (1–)2–3(–4) per cell, finely granulate to papillose or almost smooth, rarely with central eye. Dioicous. Androecia intercalary, spicate, antheridium stalk biseriate (rarely uniseriate near the base). Perianth short, but always developed, onion-shaped or conical, wider than long, mostly hidden, but rarely emergent from bracts; perigynium well developed, commonly 2–3 times longer than the perianth, with (1–)2 pairs of bracts. Elaters 2–4-spiral, spores brownish, papillose.

Marsupella is easily recognized, even in the field, due to characteristic rigid texture, transversely inserted and sheathing stem leaves, absence of underleaves, and hidden perianth. Under the microscope, additional features such as pachydermous leaf cells, defined scleroderm in stem cross section, few oil bodies, and high perigynium are helpful to refer specimens to this genus.

This paper accepts recent emendations for the circumscription of Marsupella, the most valuable being the removal of ‘perianth-less’ taxa (e.g., ‘M. commutata’) to Gymnomitrion. Five species were confirmed for this genus in Korean flora and one (M. sphacelata) regarded as likely reported erroneously.

In the specimens examined section, we cite only one specimen per locality (or 2 to 3, if they were collected at different elevations) with the intention of economizing space. Only specimens from the Korean Peninsula are cited.

Japan, Miyokosan, U. Faurie 75 (lectotype (designated here): G [009469!]).

Plants in rather loose patches, rigid to more soft, erect or nearly so, mostly deep green to brownish green in color, but with many other variants intergrading to yellowish-brownish, yellowish, and pale greenish (later only in shaded wet places) or to deep brown and rusty pigmentation in insolated moist habitats; mostly 1.2–1.6 mm wide and 7.0–15.0 mm long, with small forms starting from 0.75–1.0 mm wide and robust varying to 1.5–2.2 mm wide. Branching lateral (rare) or ventral as subfloral innovations (more common), stem transversely elliptic in the cross section, 200.0–300.0 μm high (extreme variants not included) and 250.0–350.0 μm wide; outer cells (hyaloderm) nearly thin, with small trigones, 15.0–25.0 μm along margin, scleroderm in 3–4 layers, with cells slightly smaller, very thick-walled, with lumen just 8.0–11.0 μm, inner cells (10.0–)12.0–20.0 μm, thin- to slightly thickened, with moderate in size, triangle to concave trigones. Rhizoids sparse to virtually absent, mostly colorless to brownish, in unclear obliquely to erect spreading fascicles, rarely (and very few in number) separated and deep purple. Leaves mostly contiguous and loosely enclosed one to another, to subimbricate or nearly distant in lax modifications, concave to canaliculate-concave, transversely inserted, evidently sheathing the stem in the base and obliquely to erect spreading above, transversely, subtransversely or (more rarely) obliquely oriented, with margin commonly narrowly recurved, at least in lower half of the leaf; transversely elliptic to orbicular and widely ovate in shape, mostly 500.0–750.0 μm long and 550.0–1050.0 μm wide, reaching in lax forms 1500.0–2250.0 × 1550.0–2750.0 μm, divided by sinus descending to 1/7–1/5(1/4) of leaf length into two nearly equal to subequal lobes; sinus varying from narrowly to widely γ-shaped; lobes rounded to (rarely) obtuse in apex. Cells in the midleaf subisodiametric to shortly oblong, (12.0–)20.0–25.0 × (12.0–)13.0–25.0 μm, thin-walled to slightly thickened, trigones mostly large, rarer moderate in size, convex to bulging, cuticle smooth; cells along margin in upper part of leaf 5.0–8.0(–10.0) μm, mostly unequally thickened due to trigones confluence, trigones large, convex to concave, cuticle smooth; cells in the lobe middle similar to that in the midleaf or slightly smaller, 12.0–20.0 × 11.0–15.0 μm, thin-walled, trigones large, convex to bulging, cuticle smooth. Dioicous. Androecia intercalary, spicate, with 3–4 pairs of bracts, (1–)2–3-androus, antheridium body obovate, 130.0–150.0 μm wide, stalk biseriate, 100–150 μm long; bracts strongly inflate in lower half and obliquely to erect (especially lobes) spreading above, trapezoidal-subtransversely elliptic. Perianth hidden within bracts or very shortly exerted, conical to onion-shaped, 400.0–750.0 × 750.0 μm; perigynium 750.0–1000.0 μm long, with two pairs of bracts; bracts sheathing perigynium in lower part and obliquely spreading above (lobes of lower pair commonly deflexed).

Figure 2. 

Marsupella apertifolia Steph. A male plant B female plants C stem cross section (fragment) D plant habit E–H leaves I, K cells along leaf margin J midleaf cells L gynoecium longitudinal section. Scale bars: a 1 mm (A, B, D–H, L); b 100 µm (C, I–K). All from Choi 7383 (JNU). Drawing by S.J. Park.

Acidophilic hygro- to hydrophyte, occupying various habitats, from very wet (and even submerged) shaded cliffs near running water to moist mineral substrata in full sun. In moist and sunny habitats, robust phases are formed (then commonly acquiring deep rusty-brown pigmentation), where it is associated with Anastrophyllum assimile, Trilophozia quinquedentata, and Diplophyllum taxifolium. As an extreme variant, the species may be intermixed with Gymnomitrion faurianum. In wet and shady habitats, its common association is Cephalozia otaruensis^*.

Montane temperate Kurils-Japanese-Korean endemic species is known in northern and middle Japan (until Shikoku), South Korea and South Kurils (Iturup Island), likely more widely distributed, at least to Kamchatka Peninsula in in the north. In Korea, Jeju-do, Chungcheongbuk-do, Chungchengnam-do, Gyeongsangnam-do, Gangwon-do, Jeollabuk-do and Jeollanam-do (Choi et al. 2017).

Chungcheongnam-do: Mt. Daedun, 36°08'02.9"N, 127°18'29.1"E, 343 m, 31 Mar 2009, S.S. Choi 3405 (JNU); Gangwon-do: Mt. Seorak, 38°07'21.0"N, 128°27'27.7"E, 1649 m, 21 Sep 2009, S.S. Choi 5174 (JNU), Mt. Seorak, 38°07'42.2"N, 128°26'21.6"E, 1011 m, 14 Oct 2010, S.S. Choi 8607 (JNU), Mt. Seorak, 38°07'52.7"N, 128°26'11.2"E, 937 m, 14 Oct 2010, S.S. Choi 8632 (JNU); Gyeongsangnam-do: Mt. Jiri, 35°19'20.6"N, 127°44'59.4"E, 1134 m, 14 Jun 2009, S.S. Choi 3745 (JNU), Mt. Jiri, 35°20'01.7"N, 127°43'55.1"E, 1713 m, 3 Oct 2011, S.S. Choi 111079 (JNU), Mt. Namdeogyu, 30 Oct 2008, S.S. Choi 1119 (JNU); Jeju-do: Erimok valley, 33°21'59.6"N, 126°30'40.3"E, 1591 m, 6 Sep 2012, S.S. Choi 120765 (JNU), Erimok valley, 33°21'59.6"N, 126°30'40.27"E, 1615 m, 6 Sep 2012, S.S. Choi 120797 (JNU), Mt. Halla, 33°22'02.2"N, 126°33'05.9"E, 1563 m, 8 Aug 2010, S.S. Choi 7737 (JNU), Mt. Halla, 33°21'42.1"N, 126°32'02.8"E, 1861 m, 21 Sep 2012, S.S. Choi 120904 (JNU), Hyodon stream, 33°18'21.4"N, 126°33'38.5"E, 469 m, 7 Aug 2010, S.S. Choi 7638 (JNU), Witse Oreum, 33°21'33.4", 126°30'54.2"E, 1668 m, 7 Sep 2012, S.S. Choi 120847 (JNU); Jeollabuk-do: Mt. Deogyu, 22 Nov 2008, S.S. Choi site 2-35 (JNU), Mt. Jiri, 35°19'25.0"N, 127°41'36.8"E, 1300 m, 7 Oct 2009, S.S. Choi 6090 (JNU), Mt. Jiri, 35°19'50.1"N, 127°41'33.5"E, 1100 m, 21 May 2010, S.S. Choi 7383 (JNU); Jeollanam-do: Mt. Dureun, 5 Feb 2009, S.S. Choi 3064 (JNU), Mt. Jiri, 35°19'15.3"N, 127°31'50.0"E, 755 m, 19 Sep 2009, S.S. Choi 5043 (JNU).

This species was regarded as the variety within M. emarginata subsp. tubulosa by Kitagawa (1963); however, we agree with Stephani (1901) and treat it as a separate species because of the differences in DNA sequences between two taxa (Bakalin et al. 2019). Marsupella apertifolia differs from M. tubulosa in mostly rounded lobe apices (versus mostly acute), more or less equal lobes (versus distinctly unequal), non-biconcentric oil bodies (versus biconcentric), and constant absence of red or purple pigmentation.

South Korea, Gyeongsangnam-do, Jiri Mts., National Park, 7.V.2015, Bakalin V. A. Kor-28-4-15 (holotype VBGI!, isotypes MW!, JNU!).

Plants in loose mats, more or less rigid, strongly distichous, brownish green to deep green, brownish greenish and yellowish brownish, also brown with rusty tint to brown purple, 500.0–1100.0 μm wide and 10.0–25.0 mm long. Rhizoids absent or very few, but common in geotropic stolons, colorless to grayish, obliquely to erect spreading. Stem rarely produces normal ventral branches, whereas commonly with ventral geotropic leafless stolons, almost always with 1–2 subfloral ventral or lateral innovations near gynoecia; stem cross section nearly rounded to slightly transversely elliptic, differentiated into strata, with outer layer cells 10.0–13.0 μm along margin, unequally thickened, but with thin and easily destroying external side, with moderate to small concave trigones; scleroderm well developed, in 2–3 layers, walls very thick, sometimes with visible median lamina, 7.0–10.0 μm in diameter, but with lumen only 3.0–6.0 μm in diameter, trigones moderate to large, concave; inner cells irregular in shape, 10.0–15.0 μm in diameter, walls thickened, trigones moderate, concave. Leaves distichously arranged, transversely to subtransversely inserted, obliquely spreading and subtransversely oriented, margins narrowly recurved in the both (dorsal and ventral) sides, narrowly canaliculate (looks conduplicate) with ‘keel’ slightly arched or nearly straight (in poorly developed phases), divided by gamma-shaped sinus into two strongly unequal gibbous lobes, lobe apices acute to obtuse. Cells in the midleaf mostly oblong, rarer subisodiametric, 7.0–20.0 × 7.0–13.0 μm, walls thickened, trigones large, triangle to convex, cuticle smooth, cells along lobe margin 5.0–10.0 μm, with unequally thickened walls, trigones small to moderate in size, concave, cuticle smooth; cells in the lobe middle 7.0–15.0 × 7.0–12.0 μm, with walls thickened to thin, trigones large and convex, sometimes confluent; oil-bodies (1–)2(–3) per midleaf cell, not biconcentric, spherical to oblong, ca. 5.0–7.5 × 5.0 μm. Dioicous. Androecia intercalary, with 2–3 pairs of bracts (but adjacent 1–2 pairs of ‘sterile’ leaves are similar with bracts that gives the impression of long androecia), spicate, bracts cupped to spoon-shaped, with recurved margin, suborbicular and lacerate when flattened in the slide, divided by γ-shaped sinus into two almost equal gibbous lobes, 750.0–875.0 × 825.0–1050.0 μm, 2–3-androus, antheridium stalk biseriate, 100.0–200.0 μm long, body nearly spherical ca. 100.0–120.0 μm in diameter. Perianth hidden within bracts or shortly exerted, onion-shaped, ca. 250.0 × 600.0 μm; perigynium well developed, 600.0–800.0 μm long (when archegonia fertilized), with two pairs of bracts, bracts sheathing perianth, with lobes incurved to perianth or very narrowly spreading. Elaters entirely bispiral, ca. 200.0 × 7.0–8.0 μm, with narrowed (sometimes even homogenous as in ‘Plectocolea-type’) ends. Spores brown, papillose, spherical, 10.0–11.0 μm in diameter.

Figure 3. 

Marsupella koreana Bakalin et Fedosov A stem crops section (fragment) B male plant habit C female plant habit D gynoecium longitudinal section E shoot (fragment) F, G elaters H–J leaves K midleaf cells L cells along leaf margin. Scale bars: a 100 µm (A, F, G, K, L); b 1 mm (B, C); c 1 mm (D, E, H–J). All from Choi 3511 (JNU).

Acidophilic to neutro-tolerant meso- to hygrophyte. The ecology of this species is somewhat similar to that of M. pseudofunckii. It occupies mesic, rarely moist, or dry substrates in open to partly shaded areas. Among the common associates in drier habitats, Sphenolobus minutus, in open subalpine stations, it sometimes grows together with Gymnomitrion parvitextum. In wetter habitats M. koreana may grow with Marsupella tubulosa and Cephalozia otaruensis.

Montane temperate species, known from only the southern part of the Korean Peninsula, but probably spreading northward. In Korea, Jeju-do, Chungchengnam-do, Gyeongsangnam-do, Jeollabuk-do and Jeollanam-do (Bakalin et al. 2019).

Chungcheonnam-do: Mt. Daedun, 36°08'02.9"N, 127°18'29.1"E, 343 m, 31 Mar 2009, S.S. Choi 3407 (JNU); Gyeongsangnam-do: Mt. Gaya, 35°49'14.8"N, 128°07'27.5"E, 1313 m, 8 Sep 2009, S.S. Choi (JNU), Mt. Gaya, 35°47'30.1"N, 128°05'46.3"E, 521 m, 28 Apr 2009, S.S. Choi 3511 (JNU), Mt. Gaya, 35°49'30.7"N, 128°07'07.9"E, 1350 m, 22 Jun 2010, S.S. Choi 7402 (JNU), Mt. Jiri, 35°18'51.9"N, 127°44'22.1"E, 848 m, 13 Jun 2009, S.S. Choi 3628 (JNU), Mt. Jiri, 35°19'20.6"N, 127°44'59.4"E, 1134 m, 14 Jun 2009, S.S. Choi 3686 (JNU), Mt. Namdeogyu, 31 May 2008, S.S. Choi site 1-2 (JNU), Mt. Namdeogyu, 35°45'53.5"N, 127°40'55.5"E, 1422 m, 11 Nov 2010, S.S. Choi 8950 (JNU), Jeju-do: Mt. Halla, S.S. Choi 111147 (JNU); Jeollabuk-do: Mt. Deogyu, 22 May 2008, S.S. Choi 509 (JNU), Mt. Jeoksang, 35°57'24.3"N, 127°41'86.3"E, 724 m, 18 Mar 2009, S.S. Choi 3417 (JNU), Mt. Jiri, 35°19'25.0"N, 127°41'36.8"E, 1300 m, 7 Oct 2009, S.S. Choi 1005-1 (JNU), Mt. Jiri, 35°19'06.1"N, 127°31'47.5"E, 781 m, 20 Jun 2009, S.S. Choi 4000 (JNU); Jeollanam-do: Mt. Dureun, 5 Feb 2009, S.S. Choi 3058 (JNU), Mt. Jiri, 35°17'44.0"N, 127°31'59.0"E, 1421 m, 29 Apr 2009, S.S. Choi 3527 (JNU).

This distinctive species is one of the most common Korean Marsupella members, completely misidentified with a couple of other taxa (most frequently with M. yakushimensis, M. apertifolia, M. pseudofunckii and M. tubulosa). It belongs to the peculiar group of East Asian Marsupella taxa with ‘scapanioid’ appearance. Tentatively, we suggest that M. koreana occurs in mainland China (we were unable to check whether specimens identified as M. pseudofunckii from China (Gao and Wu 2007) are in fact M. koreana), as well as in Japan. We were unable to find this taxon in areas adjacent to the Korean Peninsula northward, in the Primorsky Territory of Russia. The main distinctions between the mentioned morphologically related taxa are presented in Table 1. Marsupella koreana is most morphologically similar to M. patens (N. Kitag.) Bakalin et Fedosov (the taxon not present in Korea proper and probably limited to the Japanese Archipelago) and M. pseudofunckii. The main distinctions of the former are in recurved leaf margins that are always flat or undulate in M. patens as well as in acute to obtuse (but in any way angular) lobe end, versus rounded in M. patens. The distinctions from M. pseudofunckii are the presence of narrowly recurved leaf margins in M. koreana, shoots not or slightly dilated to the perianth (versus distinctly dilated in M. pseudofunckii) and narrowly canaliculate, but not keeled-conduplicate (as in M. pseudofunckii) leaves.

Japan, Echime Prefectura, Omogo, 27 July 1940, S. Hattori 5540 (holotype TNS [174467!])

Plants in loose mats, more or less rigid, erect to ascending, strongly distichous, brownish green to deep green, rarely brown with rusty, purplish or reddish tint near apices, strongly dilated to the perianth, 500.0–600.0 μm wide in normally developed part, with common depauperate plants (in shady and dry habitats) starting from 150.0 μm wide, near perianth much wider and reaching 1100.0 μm, 10.0–25.0 mm long. Rhizoids virtually absent with exception of leafless geotropic stolons, where common, obliquely spreading, separated or united into unclear fascicles. Stem branching ventral and (more commonly) lateral, as subfloral innovations and ventral leafless geotropic stolons that sometimes transform into normal branches; stem cross section transversely elliptic, differentiated into strata, outer layer with walls unequally thickened (but external wall thin), 12.0–25.0 μm along margin, trigones moderate, concave, scleroderm cells 10.0–13.0 μm in diameter, with strongly thickened walls and moderate in size, concave trigones, gradually transformed to inner tissue, cells in inner part 10.0–18.0 μm in diameter, walls thickened to almost thin, trigones moderate, concave. Leaves transversely inserted, not or barely sheathing stem in base, obliquely spreading, transversely oriented, evidently keeled-conduplicate with plane margin, keel straight to slightly arched or suddenly turned downward near the end, leaves contiguous to distant, rarely enclosed one to another, 220.0–430.0 μm long and 300.0–600.0 μm wide, obliquely transversely elliptic, divided by γ-shaped sinus descending to 1/4–1/3 of leaf length into two strongly unequal gibbous lobes with acute to obtuse or very rarely rounded apes. Cells in the midleaf 10.0–18.0 × 7.0–15.0 μm, walls thin, trigones moderate in size to large, triangle to convex, cuticle smooth; cells along margin 5.0–8.0(–10.0) μm, thin to (more commonly) thickened, trigones small to large, mostly concave, cuticle smooth; cells in lobe middle 7.0–15.0 × 6.0–12.0 μm, walls thin to thick, trigones moderate to large, triangle to convex. Dioicous. Androecia intercalary, spicate, with 2–3 pairs of bracts, sequential generations divided by 10 and more pairs of sterile leaves, 1–3-androus, stalk biseriate, 125.0–220.0 μm long, body nearly spherical, ca. 150.0 μm in diameter; bracts cupped to spoon-shaped, commonly with recurved margin. Perianth hidden within bracts or barely exerted, couple-shaped, ca. 150.0 μm long and 400.0 μm wide, perigynium well developed, 500.0–700.0 μm long, with two pairs of bracts; bracts sheathing perigynium and above incurved inward to the perianth if archegonia were fertilized, or obliquely spreading, if archegonia not fertilized.

Figure 4. 

Marsupella pseudofunckii S.Hatt. A plant habit B, C leaves D female plant (fragment) E male plant (fragment) F cells along leaf margin G midleaf cells H stem cross section. Scale bars: a 1 mm (A); b 100 µm (F–H); c 1 mm (B–E). All from Choi 545 (JNU).

Acidophilic meso- to hygrophyte taxon. The species occupies dry to moist cliffs, rarely wet rocks as well as stones near streams, in open to (more commonly) partly shaded places. It grows together with various Scapania and Cephaloziella or Marsupella tubulosa in wetter habitats. In dry to mesic and shady conditions, it is associated with Tetralophozia filiformis, Bazzania ovifolia, Cylindrocolea recurvifolia, Diplophyllum taxifolium, D. albicans, and Syzygiella autumnalis.

Temperate Montane East Asian species, aside from Korea known from China (Taiwan, Zheijiang (the report from the latter is based on Zhu et al. 1998)), Russian Far East (southern Sikhote-Alin only), and Japan. In Korea, Jeju-do, Chungchengnam-do, Gyeongbuk-do, Gyeongnam-do, Gangwon-do, and Jeollabuk-do (Kim and Hwang 1991; Yamada and Choe 1997). This species is here newly recorded from Gyeongsangbuk-do Province.

Chungchengnam-do: Mt. Daedun, 36°08'02.9"N, 127°18'29.1"E, 343 m, 31 Mar 2009, S.S. Choi 3414 (JNU), Mt. Gyeryong, 36°21'06.9"N, 127°12'50.9"E, 290 m, 8 Jul 2009, S.S. Choi 4083 (JNU); Gangwon-do: Mt. Seorak, 38°06'02.8"N, 128°23'43.1"E, 840 m, 28 Aug 2009, S.S. Choi 4257 (JNU), Mt. Seorak, 38°06'35.7"N, 128°25'33.7"E, 1449 m, 21 Sep 2009, S.S. Choi 5146 (JNU), Mt. Seorak, 38°07'55.5"N, 128°25'42.3"E, 805 m, 14 Oct 2010, S.S. Choi 8655 (JNU); Gyeongsangbuk-do: Is. Ulleung, Mt. Mireuk, 26 Aug 2008, S.S. Choi site5-191 (JNU), Seonginbong, 22 Aug 2008, S.S. Choi site6-48 (JNU); Gyeongsangnam-do: Mt. Jiri, 35°20'02.4"N, 127°43'54.2"E, 1720 m, 15 Jun 2009, S.S. Choi 3772 (JNU); Jeju-do: Mt. Halla, 33°21'45.3"N, 126°32'08.9"E, 1916 m, 8 Aug 2010, S.S. Choi 7757 (JNU); Jeollabuk-do: Mt. Deogyu, 22 May 2008, S.S. Choi 545 (JNU), Mt. Jeoksang, 35°57'24.3"N, 127°41'86.3"E, 724 m, 18 Mar 2009, S.S. Choi 3416 (JNU), Mt. Naejang, 35°29'16.2"N, 126°53'46.3"E, 250 m, 16 Mar 2009, S.S. Choi 3482 (JNU); Jeollanam-do: Mt. Dureun, 5 Feb 2009, S.S. Choi 3057 (JNU), Mt. Jiri, 35°17'44.0"N, 127°31'59.0"E, 1421 m, 29 Apr 2009, S.S. Choi 3537 (JNU).

This is a distinctive species belonging to the group of Marsupella with conduplicate leaves. It may be mistaken for M. koreana (distinguishing characters given under that species) or (less probably) for M. yakushimensis. The latter and M. pseudofunckii share conduplicate leaves with not revolute margins, although being different in: 1) lobes are subequal in M. yakushimensis, but strongly unequal in M. pseudofunckii, 2) leaf margin of M. yakushimensis is commonly undulate and lobe ends turned away of the stem, whereas leaf margin in M. pseudofunckii is always plane and not reflexed away from the stem, 3) shoots of M. pseudofunckii are strongly dilated to the perianth, versus almost stable shoot width in M. yakushimensis, 4) the width of sterile shoots of M. pseudofunckii generally less than 0.6 mm, but in M. yakushimensis it commonly is more than 1.5 mm.

Japan, Unzen, 5 Mar 1895, Faurie 15385 (lectotype (designated here) G [15042/00061032!])

Plants merely rigid, forming loose patches, deep green-brown, purple-brown, purple-green, or rarely greenish (actually plants extracted from the patch yellowish brownish in general, but with purple-rusty coloration in apices and upper parts of insolated leaves that gives expression of purple-brown color of patch), or yellowish greenish, pale brownish with purple tint in apical parts, rarer brownish greenish without purple or rusty pigmentation; 0.6–1.2 mm wide (the largest lax plants up to 1.3–1.5 mm) and 5.0–15.0 mm long. Rhizoids nearly absent or few, colorless. Stem brownish, not branched or branched as ventral leafless stolons (rarely becoming to normal branch) or more commonly as subfloral ventral or lateral innovations; transversely elliptic in cross section, 160.0–180.0 μm high and 200.0–250.0 μm wide (depauperate shoots omitted), differentiated into strata; hyaloderm with external wall thin, radial walls thin to unequally thickened (becoming thicker inward), inner wall thick, 15.0–20.0 μm along margin; scleroderm in (1–)2 rows of cells, cells thick-walled, but not so strongly as in M. apertifolia; inner cells thin to slightly thickened, trigones moderate in size, concave, 12.0–18.0 μm in diameter. Leaves contiguous to distant, sometimes ‘enclosed’ one to another, concave to almost flattened in upper half, transversely inserted, evidently or very loosely sheathing stem in the base, obliquely (rarely erect) spreading, subtransversely to obliquely oriented, suborbicular to widely ovate, margin flat to loosely recurved near base (especially in the leaves sheathing the stem), divided into two unequal (rarely subequal) lobes by widely V- to γ-shaped sinus descending to 1/7–1/5(1/4) of leaf length, lobe apex couple-shaped, obtuse to acute. Cells in the midleaf shortly oblong, 10.0–20.0(–25.0) × 8.0–16.0(–18.0) μm, walls thin to slightly thickened, trigones large to (rarer) moderate in size, convex to bulging, cuticle smooth; cells along leaf margin 6.0–12.0 μm, walls thin to slightly (to strongly and unequally) thickened in tangential walls, trigones moderate to large, concave to slightly convex, tangentially sometimes confluent; cells in lobe middle oblong, 15.0–22.0 × 8.0–13.0 μm, walls thin to slightly thickened, trigones moderate to large, convex to triangle. Oil-bodies in the midleaf cells 2(–3) per cell, biconcentric (at least (30–)70%), finely to normally papillose, spherical, ca. 5.0 μm in diameter to oblong, 7.5–12.5 × 5.0–7.5 μm. Dioicous. Androecia intercalary, with 1–3 or 3–5 pairs of bracts, different generations divided by 4–8 pairs of sterile leaves, spicate, 3–5-androus, stalk biseriate, 75.0–100.0 μm long, body ellipsoidal, ca. 140.0 × 115.0 μm; bracts spoon-shaped, nearly subquadrate when flattened, with deflexed to erect-spreading lobes. Perianth onion-shaped, hidden within bracts, ca. 300.0 × 500.0 μm; perigynium 500.0–700.0 μm long, with (1–)2 pairs of bracts; bracts sheathing perianth near base and erect spreading in upper 1/3–1/2. Capsule elliptic, outer layer cells rectangular, 27.0–50.0 × 20.0–25 μm, with 2(–4) nodular thickenings in vertical walls and 1(–3) thickenings in horizontal wall; inner cells elongate and flexuous, 45.0–63.0 × 7.0–10.0 μm, with 7–10 sometimes bifurcate semicircular bands. Elaters (2–)3-spiral, 150.0–180.0 × 7.0–8.0 μm. Spores brown, papillose, spherical, 10.0–12.0 μm in diameter.

Figure 5. 

Marsupella tubulosa Steph. A gynoecium longitudinal section B stem cross section (fragment) C plant habit, dorsal view D leaf margin cells E, F leaves G elater, H midleaf cells. Scale bars: 1 mm (A, C, E, F); b 100 µm (B, D, G, H). All from Choi 3732 (JNU).

Acidophilic meso- to hygrophyte. The species occupies sandy soils and mineral substrates, over wet to moist, and sometimes mesic cliffs, being most common along streams near running water. In drier habitats, it is commonly associated with Odontoschisma pseudogrossiverrucosum, Cheilolejeunea obtusifolia, and rarely with Microlejeunea punctiformis, Cephaloziella spp., Gymnomitrion faurianum. In wetter habitats M. tubulosa sometimes grows intermixed with Solenostoma minutissimum, Lophocolea horikowana, Marsupella pseudofunckii, and M. koreana.

The distribution of the species is confined to insular and peninsular areas in Amphi-Pacific Boreal and Temperate Eastern Asia, while the records provided by Bakalin, (2010), Cherdantseva and Gambaryan (1986), Gambaryan (1992, 2001), Konstantinova et al. (2002) for the Russian Far East continental mainland are likely incorrect. This species is strikingly characterized by biconcentric oil bodies – an uncommon feature in Marsupella that has never been reported from continental Asia or from North America. This suggests the reports of the species in Schuster (1974) for North America and Schljakov (1981) for Russian Asia are incorrect. We suggest the ‘true’ M. tubulosa (the type is from Honshu) occurs only in Japan, Kurils, Kamchatka and the Korean Peninsula, as well as probably in China (Anhui, Taiwan), from where, unfortunately, oil bodies were not studied. All specimens collected in the continental mainland of the Russian Far East and checked alive had non-biconcentric oil bodies, whereas specimens from peninsular and insular parts of the Far East possess biconcentric oil bodies. The species was recorded for nearly all provinces of the Korean Peninsula (Jeju-do, Gyeongsangnam-do, Gyeongsangbuk-do, Chungcheongnam-do, Chungcheongbuk-do, Gyeonggi-do, Gangwon-do, Pyeonganbuk-do, Hamgyeongnam-do, Hamgyeongbuk-do: Yamada and Choe 1997; Kim and Hwang 1991) and was confirmed for most of the provinces in the southern part of the peninsula.

Chungcheongnam-do: Mt. Daedun, 36°08'02.9"N, 127°18'29.1"E, 343 m, 31 Mar 2009, S.S. Choi 3399 (JNU), Mt. Gyeryong, 36°21'06.9"N, 127°12'50.9"E, 290 m, 8 Jul 2009, S.S. Choi 4098 (JNU); Gangwon-do: Mt. Seorak, 38°06'02.8"N, 128°23'43.1"E, 840 m, 28 Aug 2009, S.S. Choi 4258 (JNU), Mt. Seorak, 38°06'39.7"N, 128°24'56.2"E, 1347 m, 21 Sep 2009, S.S. Choi 5095 (JNU), Mt. Seorak, 38°07'21.0"N, 128°27'27.7"E, 1649 m, 21 Sep 2009, S.S. Choi 5175 (JNU); Gyeongsangbuk-do: Is. Ulleung, Seonginbong, 37°29'39.5"N, 130°52'35.4"E, 845 m, 20 Oct 2010, S.S. Choi 8712 (JNU), 37°29'53.9"N, 130°52'01.0"E, 977 m, 20 Oct 2010, S.S. Choi 8744 (JNU); Gyeongsangnam-do: Mt, Gaya, 35°48'53.9"N, 128°07'21.9"E, 1116 m, 8 Sep 2009, S.S. Choi 4361 (JNU), 35°49'14.8"N, 128°07'27.5"E, 1313 m, 8 Sep 2009, S.S. Choi 4376 (JNU), Mt. Jiri, 35°18'51.9"N, 127°44'22.1"E, 848 m, 13 Jun 2009, S.S. Choi 3641 (JNU), 35°19'50.7"N, 127°44'08.1"E, 1540 m, 14 Jun 2009, S.S. Choi 3732 (JNU); Jeju-do: Bolre Oreum, 33°21'20.8"N, 126°28'10.2"E, 1145 m, 5 Sep 2012, S.S. Choi 120721 (JNU), Erimok valley, 33°21'59.6"N, 126°30'40.25"E, 1613 m, 6 Sep 2012, S.S. Choi 20795 (JNU), Mt. Halla, 33°21'43.1"N, 126°32'21.9"E, 1835 m, 8 Aug 2010, S.S. Choi 7745 (JNU), Musu stream, 33°25'08.0"N, 126°26'56.4"E, 495 m, 28 Oct 2010, S.S. Choi 8827 (JNU), Suak valley, 33°20'14.0"N, 126°36'37.8"E, 523 m, 29 Oct 2010, S.S. Choi 8879 (JNU); Jeollabuk-do: Mt. Deogyu, 30 Jun 2008, S.S. Choi 887 (JNU), Mt. Jiri, 35°19'06.1"N, 127°31'47.5"E, 781 m, 20 Jun 2009, S.S. Choi 3993 (JNU); Jeollanam-do: Mt. Dureun, 5 Feb 2009, S.S. Choi 3061 (JNU), Mt. Jogyeo, 34°59'51.6"N, 127°16'51.7"E, 288 m, 7 Dec 2010, S.S. Choi 9094 (JNU).

This species may be confused with at least three other species: Marsupella koreana, M. apertifolia, and M. emarginata, though the last is not known from the Korean Peninsula. The distinctions between the former two are mentioned under those species. The species differs from M. emarginata (with which M. tubulosa was probably confused in parts outside of oceanic/suboceanic Eastern Asia) in biconcentric oil bodies (versus oil bodies without the central eye) and commonly obliquely oriented leaves that are not closely sheathing the stem in the base (versus transversely oriented leaves with leaves closely sheathing the stem near base). The latter feature is surely quantitative and variation in leaf orientation occurs within the two species.

Malaysia. North Borneo: Mt. Kinabalu National Park, S. slope, around Paca Cave, 2985 m, Mizutani, 2788 (not seen).

Plants strongly vermicular, forming loose patches, brown to blackish brown, without red or purple pigmentation, orbicular in cross section, 100.0–140.0 μm in diameter, 3.0–6.0 mm long, freely ventrally branched, from leafless brownish to whitish in color densely ventrally branched rhizome. Rhizoids virtually absent, to solitary, colorless, obliquely spreading, short (less than 100.0 μm long). Stem 100.0–170.0 μm in diameter, orbicular in cross section, outer layer cells with external wall thin to obscurely thickened, tangential walls subequally thickened, trigones small, concave, walls brown in color, 6.0–10.0 μm in diameter, inner cells with walls unequally thickened, walls colorless, trigones moderate in size, concave. Leaves appressed to the stem (commonly lacerate into two segments when try to detach), transversely inserted and oriented, not decurrent, widely triangular, 65.0–110.0 μm long and 90.0–175.0 μm wide, divided by V-shaped sinus descending to 2/5–1/2 of leaf length into two subequal triangle lobes with acute apices. Cells in the midleaf 5.0–10.0 × 5.0–8.0 μm, walls moderately thickened, trigones small, concave; cuticle smooth; oil-bodies 1–2 per cell, spherical, 2.0–3.0 μm in diameter. Dioicous. Pants suddenly dilated to the perianth, to form club-shaped structure, perianth completely hidden within bracts, nearly conical, 75.0–100.0 μm long and 200.0–230.0 μm wide, smooth, perigynium 120.0–150.0 μm long, with one pair of bracts; bracts nearly orbicular to orbicular-triangular in shape, ca. 250.0 × 250.0 μm, covering perianth and then occlude one with another.

Figure 6. 

Marsupella vermiformis (R.M.Schust.) Bakalin et Fedosov A gynoecium longitudinal section B, C plant habit, fragments D plant habit E stem cross section. Scale bars: a 500 µm (A–C); a 1 mm(D); b 100 µm (E). All from Choi 120911 (JNU).

Figure 7. 

Gymnomitrion noguchianum S.Hatt. A, B, F leaves C plant habit (fragment) D plant habit E lacerate leaf apex G cells along leaf margin H stem cross section (fragment). All from Choi 120826 (JNU); Marsupella vermiformis (R.M.Schust.) Bakalin et Fedosov I, J leaves K plant habit (fragment). All from Choi 120911 (JNU). Scale bars: a 250 µm (A–C, F); a 500 µm (D); b 100 µm (E, G–J); c 100 µm (K).

Acidophilic meso-xerophyte. In Korea, it occurs on dry well-exposed rocks in large block gravelly barrens in the crater rim of Halla Mt. Marsupella vermiformis formed pure patches or a slight admixture of Gymnomitrion faurianum or dwarf form of Marsupella tubulosa.

Strongly disjunct rare taxon ranging the area from southernmost Korea (Jeju-do) across China, to Malaysia and Papuasia (Bakalin et al. 2019). The species belong to the oligotypic section Stolonicaulon (N.Kitag.) Vaňa, which it shares with rare South and South-East Asian M. stoloniformis N.Kitag.

Jeju-do: Mt. Halla, 33°21'42.1"N, 126°32'02.8"E, 1861 m, 21 Sep 2012, S.S. Choi 120911, 120897 (JNU, VBGI).

The very distinctive species, superficially quite similar to Gymnomitrion pacificum Grolle due to vermicular shoots and never spreading, but closely appressed leaves, forming in female branches, a club-like structure. It is clearly different from G. pacificum in having much smaller leaves, with normally developed cells along the margin and presence of distinct perianth. The species may be mistaken for dwarf forms of arctic-alpine sub-circumpolar amphi-oceanic Marsupella boeckii (Austin) Lindb. ex Kaal. and, possible, European (amphi-Atlantic) – British Columbian (cf. Paton 1999) Marsupella stableri Spruce. However, besides distinct gaps in distribution this species differs: 1) the never spreading leaves in M. vermiformis versus at least slightly spreading in perianthous shoots in M. boeckii and obliquely spreading to squarrose in M. stableri, 2) shoot width not exceeding 140.0–170.0 μm, versus 200.0–500.0 μm in M. boeckii, and 100–400 μm in M. stableri, 3) small cells with brown colored, thickened tangential walls in stem cross section in M. vermiformis, versus large and hyaline cells in M. boeckii and M. stableri), 4) small leaves that are wider than long, reaching at maximum 175.0 μm wide and 110 μm long, versus 200–300 μm wide in M. boeckii and distinctly longer than wide (up to 300 × 200 μm) in M. stableri, 5) very small leaf cells, 5.0–10.0 × 5.0–8.0 μm in M. vermiformis, versus 12.0–20.0 × 12.0–20.0 μm in M. boeckii and 10–16 μm in diameter in M. stableri. The distinction from M. stoloniformis (hardly possible in Korea) as well as the phylogenetic position of both is discussed by Bakalin et al. (2019).

Japan. Kagoshima Pref., Yakushima Island, Horikawa, 11895 (not seen).

Plants in loose patches, deep green-brown, yellow-brown, yellowish brownish, rarely with purple tint, (1.0)1.5–2.1 mm wide and 15.0–50.0 mm long, rigid. Rhizoids nearly absent to very sparse, colorless, obliquely spreading, however common in basal part of ventral branches and leafless stolons. Stem easily laterally and ventrally branched giving start to normal branches or geotropic leafless stolons; stem transversely elliptic in cross section 210.0–240.0 μm high and 250.0–320.0 μm wide, distinctly differentiated into strata, hyaloderm cell walls moderately thickened (but external wall thin), with small concave trigones, 17.0–25.0 μm along margin, scleroderm cells with very thick walls and visible median lamina, 12.0–17.0 μm in diameter, but with lumen disappearing or only 2.0–6.0 μm in diameter, inner cells with moderately thickened walls and moderate in size, concave trigones, 10.0–15.0 μm in diameter. Leaves strongly conduplicate and distichously arranged that gives ‘scapanioid’ appearance, contiguous to imbricate, as a rule enclosed one to another, obliquely spreading and transversely oriented, when flattened subquadrate, rectangular or obovate to suborbicular (mostly wider than long, but sometimes longer than wide), bistratose in lower 1/5–1/6 of the leaf length, 675.0–1250.0 μm long and 800.0–1500.0 μm wide, commonly dorsally secund, divided by γ-shaped sinus descending to 1/4–2/5 of leaf length into two equal to subequal lobes (either ventral or dorsal may be smaller), lobes gibbous, with obtuse to acute or rarely rounded apex. Cells in the midleaf subisodiametric to (mostly) oblong, 12.0–25.0 × 7.0–20.0 μm, strongly thick-walled, with moderate to small, concave trigones, cuticle smooth; cells along leaf margin 7.0–10.0 μm, thick-walled (but with much thinner external wall), with moderate in size, concave trigones; cells in lobe middle 10.0–17.0 × 8.0–15.0 μm, thick-walled, with small to moderate in size, concave trigones, cuticle smooth. Dioicous. Androecia intercalary, with 2–3 pairs of bracts, spoon-shaped, with revolute margin and commonly deflexed lobe ends. Perianth (only unfertilized were found) hidden within bracts, onion-shaped, perigynium the same length with perianth or slightly longer, with 2 pairs of bracts and 1–3 lateral and ventral subfloral innovations.

Figure 8. 

Marsupella yakushimensis (Horik.) S.Hatt. A plant, dorsal view B stem cross section (fragment) C cells along leaf margin D midleaf cells E–H leaves. Scale bars: a 2 mm (A); b 1 mm (E–H); c 100 µm (B–D). All from Choi-1067 (JNU).

Acidophilic hygro- to hydrophyte. The species occurs on wet cliffs at a distance from watercourses or on stones washed with sluggishly running water in partly shaded habitats in the middle elevation of mountains covered with evergreen to deciduous broadleaved forests. Commonly, the species forms pure patches or rarer, associated with Scapania undulata.

South temperate to subtropical Montane East Asian endemic species known in China (Anhui, Fujian, Guangdong, Jiangxi, Zhejiang), the southern part of the Korean peninsula (the report by Kim and Hwang (1991) for North Korea is doubtful) and the southern half of Japan. The species was reported from Gyeongsangnam-do, Gangwon-do, Gyeongbuk-do (Kim and Hwang 1991; Yamada and Choe 1997) and here added to Jeollabuk-do and Jeju-do. The specimen included in the phylogenetic tree in Bakalin et al. (2019) under the name Marsupella alata S.Hatt. et N.Kitag. (Republic of Korea, Seorak Mt., 11.V.2011, Bakalin, Kor-6-28a-11, VBGI) was re-studied and found as the dwarf modification of M. yakushimensis. Although the distinctive differences between cited specimen and another accession of M. yakushimensis may suspect more robust than infraspecific differences that should be considered in future studies of the genus in East Asia.

Gangwon-do: Mt. Seorak, 38°09'34.3"N, 128°28'10.5"E, 631 m, 11 Oct 2010, S.S. Choi 8347 (JNU); Gyeongsangnam-do: Mt. Jiri, 35°19'58.3"N, 127°44'27.5"E, 1327 m, 4 Oct 2011, S.S. Choi 111125 (JNU); Jeollabuk-do: Mt. Jiri, 35°19'25.0"N, 127°41'36.8"E, 1300 m, 7 Oct 2009, S.S. Choi 6083 (JNU), Mt. Jiri, S.S. Choi 1067 (JNU); Jeju-do: Seogwipo-si, 33°18'30"N, 126°30'30"E, 600–800 m alt. 13 May 2015, V.A. Bakalin s.n. (VBGI).

This large and beautiful species is a rarity within the Korean flora and is known only from a few localities. Unlike Japanese populations, the Korean populations acquire purple to red pigmentation as an exception. The main characteristic of the species includes nearly equal lobes that do not have recurved margins, but commonly undulate and/or turned antically. Another characteristic feature is the absence of a distinctly sheathing leaf base. Dwarf plants of M. yakushimensis may be mistaken for M. koreana, and the distinctions are given under the latter. This species is regularly observed with androecia and rarely with archegonia. Androecious and gynoecious plants were intermixed within two specimens; however, we were unable to observe fertilized (in at least two descendant generations) and fully developed perianth. Whether this is the norm or not is not clear.

Plants worm-shaped to ribbon-like, with densely imbricate leaves or similar to Marsupella and with loosely spreading leaves, rigid to soft, whitish to brownish, brown, rusty, and blackish brown, without red or purple pigmentation. There are two kinds of phenotypes: Gymnomitrion in the old sense and the former genus Apomarsupella R.M. Schust. nested within Gymnomitrion (cf. Shaw et al. 2015). The first phenotype, with imbricate leaves and stems creeping to ascending, subclavate, from rhizomatous base, dorsiventrally compressed, commonly immersed to the substrate and incrusted by soil particles. The second phenotype comprises plants with spreading leaves with shoots dorsiventrally not compressed, as well as having a not evident rhizomatous base. In both ‘phenotypes’ rhizoids are common in the rhizomatous shoot base and geotropic stolons, but rare in leafy parts of the shoot, soft, colorless to grayish or rarely and solitarily deep purple. Stem not evidently different in strata, rather it is monomorphic (outer layer cells slightly larger), cells with unequally thickened walls, and well-developed trigones. Leaves lobed to unlobed or shallowly emarginate, with plane or narrowly recurved margin. Leaf cells pachydermous, commonly with the rim of discolored cells. Dioicous (taxa known in Korea). Androecia intercalary, (1–)2(–3)-androus, stalk biseriate. Perigynium and perianth virtually absent or strongly reduced. Elaters bispiral.

This treatment follows the recent emendations e.g. transfer to Gymnomitrion of the taxa Marsupella commutata (Limpr.) Bernet and Apomarsupella revoluta (cf. Shaw et al. 2015). These transfers made Marsupella more monomorphic in the series of features, but resulted in greater polymorphism in vegetative characters of Gymnomitrion, which now includes many taxa of ‘marsupelloid’ habit, although in reproductive characters is characterized by an absence, or strong reduction of, perianth and perigynium.

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

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.

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.

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.

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).

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

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

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.

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).

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.

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.

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).

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).

Japan. Tottori Prefecture, Daisen Mt., 1400 m, on volcanic rocks, 8 August 1947, A. Noguchi s.n. (holotype: NICH [13067!]).

Plants in loose mats, more or less soft, leaved part of shoots distinctly clavate from rhizomatous base, dorsiventrally compressed, whitish to whitish green or almost completely white, immersed to soil and incrusted by soil particles, 250–350 μm wide and 500–700 μm long in leaved part, rhizomatous part ca. 3–5 mm long. Rhizoids common to (in rhizomatous base) dense, erect to obliquely spreading, separated or in unclear fascicles. Stem freely ventrally branched in the base of leaved part and variously and feely branched in rhizome; slightly transversely elliptic in cross section, ca. 100 μm high and 120 μm wide, without evident differentiation into layers, outer cells 12–15 μm along margin, with thick walls (become noticeable thinner to thin in ventral epidermis), with moderate in size, concave trigones, inner cells 7–13 μm in diameter, irregular in shape, with thickened walls and moderate to small in size concave trigones. Leaves densely imbricate, transversely inserted, not sheathing at base, transversely oriented, widely ovate-lingulate to widely triangular, cupped to spoon shaped, lacerate when flattened, 220–330 μm long and 270–500 μm wide, with rounded to emarginate apex and entire to crenulate margin. Cells in the midleaf subisodiametric (mostly quadrate) to oblong (mostly rectangular), 12–25 × 12–20(23) μm, walls thickened, trigones small to moderate in size, concave, cuticle smooth; cells along leaf margin 5–15 μm, mostly elongate perpendicularly to the margin, walls unequally thickened, trigones small to moderate, concave. Dioicous. Androecia intercalary, with cupped and loosely imbricate bracts. Perianth and perigynium absent, perichaetial area of the shoot distinctly wider than below.

Acidophilic meso-xerophyte. The species occupies dry to mesic fine soils in well-exposed places at higher altitudes. It is commonly associated with dwarf xeric forms of Marsupella tubulosa, Gymnomitrion parvitextum, and Cephaloziella divaricata.

Temperate Montane Eastern Asian endemic species with distribution confined to Japanese Honshu and Kushu as well as the southern tip of Korea (Jeju Island).

Jeju-do: Mt. Halla, 33°21'51.0"N, 126°31'42.9"E, 1814 m, 7 Sep 2012, S.S. Choi 120809, 120812, 120826 (JNU).

Due to the presence of entire to emarginate leaves, Gymnomitrion noguchianum is unlikely to be mistaken for other members of this genus. However, it may be mistaken for Cryptocoleopsis imbricata, but that species is not yet known from the Korean Peninsula, though it should be expected to occur there. Both taxa are similar in prostrate growth, occurring in well-exposed places, and entire imbricate leaves. However, two taxa may be easily separated by 1) leaf cell walls are thickened and smaller in G. noguchianum, versus larger (more than 20 μm wide) and thin-walled in Cryptocoleopsis imbricata, 2) total absence of brown pigmentation in G. noguchianum versus almost constant presence in Cryptocoleopsis; and 3) presence of calyptral perigynium in Cryptocoleopsis – the structure does not occur in Gymnomitrion.

Japan, Tosa, Mt. Tsutsujo, August 1898, Inoue n. 22 (lectotype (designated here): G [9470/00067518!]).

Plants in loose patches, rigid, slightly glistening when dry, hardly soaking, yellowish, yellow-brown and yellowish greenish, without red or purple pigmentation, 450.0–1000.0 μm wide and 3.0–20.0 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, 125.0–175.0 μm high and 150.0–190.0 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, triangle to convex. Leaves distichously spreading, enclosed one to another, concave-canaliculate to concave and spoon-shaped, transversely inserted, barely or not sheathing the stem in the base, transversely oriented, sometimes secund dorsally, elliptic to loosely widely ovate or obovate or nearly rectangular, 360.0–670.0 μm long and 500.0–625.0 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 the midleaf 8.0–20.0(–23.0) × 8.0–17.0 μm, walls thin, trigones large, bulging, cuticle smooth; cells along margin 6.0–11.0 μm, with thin to thickened walls, trigones large, bulging or convex, sometimes confluent, in robust phases protrudent in external wall that gives expression of crenulate margin, 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 with hemispherical papillae. Dioicous. Androecia intercalary, with 2–4 pairs of bracts (adjacent pairs of leaves somewhat similar in shape with bracts that may be misinterpreted as bracts), spicate, 1(–2)-androus, stalk biseriate, ca. 100.0 μm long, body nearly spherical ca. 130.0–140.0 μm in diameter; bracts spoon-shaped, with more widely than in leaves recurved margin, widely ovate-trapezoidal when flattened. Perianth entirely absent; perigynium absent or very low (up 100.0 μm long); bracts similar to leaves, but longer; commonly with 1–2 subfloral innovations becoming into normal branch and fertilized soon again or forming flagelliform brown colored branch (in drier habitats).

Figure 10. 

Gymnomitrion parvitextum (Steph.) Mamontov, Konstant. et Potemkin A female plant (fragment) B male plant (fragment) C leaf lobe apex D–G leaves H midleaf cells I gynoecium longitudinal section J stem cross section (fragment). Scale bars: a 1 mm (A, B, D–G); a 500 µm (I); b 100 µm (C, H, J). All from Choi 8475 (JNU).

Acidophilic meso-xerophyte. The species occupies more or less dry substrata in exposed to (rarely) partly shaded habitats. It is commonly intermixed with Marsupella tubulosa, M. koreana, M. pseudofunckii, Gymnomiotrion faurianum, Herbertus dicranus, Anastrophyllum assimile, or (as exotic variant) with Scapania ampliata.

East Asian oro-boreal taxon, known in areas adjacent to the Korea from the Russian Far East, Japan, and likely should be found in China. It was recorded in Korea from Gyeonggi-do, Gyeongsangnam-do, Hamgyeongnam-do (Kim and Hwang 1991; Yamada and Choe 1997) under the name Marsupella commutata. It is also reported from Gangwon-do.

Gangwon-do: Mt. Seorak, 38°08'02.8"N, 128°28'03.6"E, 908 m, 12 Oct 2010, S.S. Choi 8383 (JNU), Mt. Seorak, 38°07'34.9"N, 128°27'16.0"E, 1487 m, 12 Oct 2010, S.S. Choi 8475 (JNU); Gyeongsangnam-do: Mt. Jiri, 35°19'20.6"N, 127°44'59.4"E, 1134 m, 14 Jun 2009, S.S. Choi 3703 (JNU), 35°20'10.6"N, 127°43'42.0"E, 1820 m, 15 Jun 2009, S.S. Choi 3816 (JNU), Mt. Namdeogyu, 35°45'53.5"N, 127°40'55.5"E, 1422 m, 11 Nov 2010, S.S. Choi 8954 (JNU).

Easily recognizable species in most cases, although confused several times with dwarf plants of Marsupella tubulosa from which it differs in commonly present subquadrate to quadrate trigones in leaf lobe cells, almost constantly recurved leaf margin, and in the absence of perianth. Gymnomitrion parvitextum is morphologically similar to G. alpinum. The two taxa are distinct in the presence of subquadrate trigones in leaf lobe cells in G. parvitextum (absent in G. alpinum), recurved margin (versus margin plane), shortly or barely decurrent leaf base (versus long decurent leaf base on both sides in G. alpinum) and inability to develop red or purple pigmentation (versus such coloration common in G. alpinum).

The bigger problem is the delimitation of Gymnomitrion parvitextum from morphologically similar and ‘semicryptic’ (Mamontov et al. 2018) G. commutatum (Limpr.) Schiffn., disjunct, mostly northern hemiarctic species. Gymnomitrion parvitextum differs from G. commutatum in the following features: 1) pale yellowish to brownish and even yellowish-greenish coloration, but never blackish brown and rusty-brown coloration so common in G. commutatum, 2) leaves semi-distichously arranged versus leaves subimbricate, 3) leaves in the vast majority of cases with widely recurved margins, versus margin recurved narrowly and commonly near the leaf base only.