Ramudaria lamellicaulis (D.K.Singh, S.Majumdar & D.Singh) D.K.Singh, S.Majumdar, D.Singh & Molinari

Xu, Hao, Xu, Jing-Jing, Ma, Xiao-Ying & Zhu, Rui-Liang, 2022, Taxonomic notes and range extension of the monospecific genus Ramudaria (Lophocoleaceae, Marchantiophyta) endemic to India, Phytotaxa 556 (2), pp. 160-168 : 163

Ramudaria lamellicaulis (D.K.Singh, S.Majumdar & D.Singh) D.K.Singh, S.Majumdar, D.Singh & Molinari . Indian J. Forest. 43(2): 191. 2021(2020)

≡ Udaria lamellicaulis D.K.Singh, S.Majumdar & D.Singh, Curr. Sci. 115(8): 1537. 2018.

≡ Pandea lamellicaulis (D.K.Singh, S.Majumdar & D.Singh) U.B.Deshmukh. Phytotaxa 482(3): 291. 2021.

Type:— India. Eastern Himalaya, Sikkim, North district, Zakthang , 27°46′55.8″ N, 88°28′09.4″ E, ca. 3360 m, 24 March 2013, D. Singh 60533A (holotype & isotype: CAL, not seen) .

Plants delicate, light yellowish green when live, pale whitish-green to slightly brown in herbarium. Shoots minute, 0.5−1.4 mm wide. Stem elliptical to sub-orbicular in transverse section, (115−)130−225 µm in diameter (not including lamellar projections), 7–11 cells across diameter, cortical cells and medullary cells undifferentiated, outer cells 16−29×15−27 µm, inner cells 14−27×13−26 µm, thin-walled, mostly hyaline, non-trigonous, both dorsal and ventral surface covered with serially arranged, 1−3(−4) cells high, longitudinal lamelliform strips, strip cells subquadrate to rectangular, 13−24×12−18 µm. Branching scarce, exclusively of ventral-intercalary type; stolons absent. Leaves alternate, obliquely inserted to stem, distant, contiguous towards apical portion, obliquely or widely spreading, quadrate-rectangular, asymmetrical, lateral margin ± incurved, 0.57−0.69 mm long, 0.50−0.64 mm wide at middle, usually slightly long than wide, bifid to 0.35−0.45 of leaf length, sinus acute to widely U-shaped, dorsal margin slightly wavy, most entire to slightly crenulate, almost straight to slightly arched, base long decurrent, ventral margin slightly wavy, almost entire to slightly crenulate, almost straight to slightly arched, base slightly decurrent, lobes triangular to broadly triangulate, equal or unequal, 12−15 cells long, 9−11 cells wide at base, apex acute to subacute, ending by 1−2 uniseriate cells usually fallen off. Leaf cells thin-walled, subquadrate, trigones triangular, slightly bulging towards base, marginal cells 14−28(−36)×12−19(−22) µm, median cells 14–28×15–49 μm, basal cells 21–49×17–30 μm. Oil bodies almost colorless, but usually reflecting the color of chloroplasts, 3−7 per median cell of leaf lobe, circular to elliptical, 3.0−9.0×2.6−5.0 μm, granular. Underleaves small, free from leaf, distant to contiguous, ovate-rectangular, 0.32–0.50 mm long, 0.27–0.43 mm wide (without tooth), 1.5–2.5 times as wide as stem, bilobed to 1/2−2/3 of their length, sinus usually narrow, rarely broad, lobes parallel-divergent or sometimes slightly connivent, triangulate, 9–24 cells long, 4–10 cells wide at base, usually capped by a slime papilla at the tip, margin usually toothed with 1–2 distinct, or sometimes blunt tooth present along both the lateral margins, tooth triangulate, sometimes spinose, 1–3(−4) cells long, 1–5 cells wide at base, 1–3(−4) cells uniseriate towards apex, usually capped by a slime papilla at the tip. Rhizoids fasciculate from the lamina of underleaves, sometimes also from ventral surface of stem, hyaline, ± branched at the tip. Dioicous (?). Androecia not seen. Gynoecia terminal on main shoots with (0−)1 innovation, bracts and bracteoles in 2−3 series, those of outermost series slightly smaller, bracts of innermost series larger (0.9−1.4 mm long, 0.7−0.8 mm wide), almost symmetrically or more often asymmetrically, bifid to ca. 0.3−0.6, lobes acute, apex usually ragged, gemmiparous, lamina without abaxially lamellate projections, lamina margins each with 0−3 teeth, teeth small and few-celled, bracteoles of innermost series somewhat smaller than bracts, subrectangular, up to 1.3 mm long, free or narrowly connate on one side, symmetrically or symmetrically bifid to ca. 0.3−0.5, lobes acute, often ragged at apex, gemmiparous, lamina margins entire or with a few small teeth. Perianth long exserted, oblong-elliptic, not or slightly narrowed toward 3-lobed mouth, obscurely trigonous above, with 3 keels: two lateral and one dorsal, 1.4–2.1 mm long, 0.6–1.0 mm wide, surface smooth, both outer and inner surface sometimes with lamelliform strips 1−3 cells high. Sporophytes not seen. Asexual reproduction by caducous leaves or unicellular gemmae, gemmae infrequent, smooth, pale green, globose, at the apex of leaf lobes and female bract lobes, linear-filamentous gemmae not seen.

Specimen examined:— China. Xizang, Bomi Co., near Galongla tunnel, 95°41′45.10″ E, 29°45′57.38″ N, 3841 m, on soil in the moist coniferous forests, 25 Sept. 2020, Xiang et al. 20200925-50B (HSNU) .

Taxonomic notes on Ramudaria lamellicaulis

The collection of Ramudaria lamellicaulis from China was made in Xizang, where the world’s highest peak of Mount Qomolangma with an elevation of 8,848 m is located. Regrettably, only several shoots, which were mixed with several large liverwort and moss species, including Heteroscyphus Schiffner (1910: 171) sp. , Lophoziopsis excisa ( Dickson 1793: 11) Konstantinova & Vilnet (2010: 66) , Plagiochila Dumortier (1831: 42) Dumortier (1835: 14) sp. , Plagiomnium succulentum ( Mitten 1859: 143) Koponen (1968: 147) , and Sanionia uncinata ( Hedwig 1801: 289) Loeske (1907: 309) , were available. The Chinese plant is very similar to Lophocolea minor Nees (1836: 330) widespread in America, Asia, and Europe but undoubtedly belongs to Ramudaria because of the presence of longitudinal, serially arranged lamelliform strips on the surface of the stem ( Fig. 1H, 1J ). Further examination of the Chinese sample, however, shows that several characters do not agree well with those described in the protologue of R. lamellicaulis . The leaf cell cuticles are striolate-rugulose papillose in Indian collections, but smooth in the Chinese sample ( Fig. 1I , Fig. 2D ). The lamelliform strips on the surface of the underleaf, leaf and bract are absent ( Fig. 1 B−E) (vs. occasionally present in Indian samples), but sometimes present on the out surface and inner surface of the perianth ( Fig. 1D, 1G ) in the Chinese sample (vs. absent in Indian samples). In addition, the longitudinal lamelliform strips on the surface of the stem are only 1−3 cells high in the Chinese collection (vs 1−12 cells high in Indian collections). In the protologue, Singh et al. (2018) described the rhizoids arising from the lamina of the underleaf. Our observations based on the Chinese sample reveal that rhizoids do not only arise from the lamina of the underleaf, but much like some other species of Lophocolea , also from the underleaf base and the ventral surface of the stem ( Fig. 2F ). As the Indian samples were not accessible and only a scanty Chinese sample was available for our study, the question whether the Chinese plant belongs to a poorly developed, local form of R. lamellicaulis or represents a separate species remains unresolved until further collections are available for a comparative study. No matter how different the Chinese plant is from the Indian one, we prefer to assign the Chinese plant to R. lamellicaulis to avoid even more unnecessary superfluous names.

Figures

FIGURE 1. Ramudaria lamellicaulis. A: Portion of shoot, ventral view. B: Female bract. C: Female bracteole. D: Gynoecium showing a perianth, ventral view. E: Leaf. F: Transverse section of stem, showing 1−3 cells high strips. G:Transverse section of perianth at middle.H: Longitudinal lamelliform strips on the dorsal surface of stem. I: Median cells of leaf, showing smooth cuticle. J: Longitudinal lamelliform strips on the ventral surface of stem.All from Xiang et al. 20200925-50B (HSNU).

FIGURE 2. Ramudaria lamellicaulis. A−C: Underleaves and rhizoids from underleaf lamina and base. D: Median cells of leaf showing trigones. E: Portion of shoots, showing branching. F: Portion of stem, ventral view, showing rhizoids from stem surface. All from Xiang et al. 20200925-50B (HSNU).