Ptilidium himalayanum Vilnet, Bakalin & Hentschel, 2021

Bakalin, Vadim, Vilnet, Anna, Klimova, Ksenia, Ma, Wen Zhang, Choi, Seung Se & Hentschel, Jörn, 2021, Hidden in plain view: an example from Ptilidium (Ptilidiaceae, Marchantiophyta), Phytotaxa 510 (1), pp. 29-42 : 38

Ptilidium himalayanum Vilnet, Bakalin & Hentschel sp. nov.

Description: Plants prostrate, or loosely ascending in some apices, rusty brown to yellowish brownish, tinged with copper and green (the coloration as bright as commonly occurs in some alpine modifications of P. ciliare var. ciliare ), 15–40 mm long and 1.0– 1.5 mm wide. Rhizoids sparse, from the stem in areas closely adjacent to the underleaf bases, in colorless to brownish fascicles, ca 0.4 mm long, erect spreading. Stem freely pinnately and rarely bipinnately branched, the branches of the first order commonly become to the new axis in bipinnately branched shoots, branching of Frullania type (‘instead’ ventral half of the leaf); stem cross section transversely ellipsoidal, in well-developed shoots ca 175 × 275 µm, with thick external wall, other walls thick to thin (inward especially so), trigones triangular, large, cells along cross section margin 15–25 µm long, inward to 33 µm in diameter. Leaves imbricate, incubously oriented, almost transversely inserted, convex, densely imbricate, turned to ventral side, lobed into 5 lobes (the smallest lobe may be indistinct to lacking) by V- to U-shaped sinus descending for 1/2–2/3 of leaf length, lobes strongly unequal (dorsal larger), the ventral lobe sometimes reduced to small hunch, 0.8–1.1 × 1.2–1.6 mm including cilia, margin strongly ciliate, with cilia number varying from 5 (in small lobes) to 15 (in larger ones). Underleaves imbricate, convex (if looking from ventral side), reniform to transversely ellipsoidal, apex emarginate to shortly bilobed, densely toothed throughout, although sometimes lateral sides may be free of teeth, in larger underleaves apical teeth sometimes branched (bifurcate) (the feature never occurring in leaves), 450–600 × 750–1000 µm. Cells in the middle of leaf lamina shortly oblong, 25–45 × 20–25 µm, thin-walled, with large, triradiate trigones, with visible middle lamina; cells in the middle of cilia 30–40 × 15–20 µm, with thick to merely thin lateral walls and large nodulose trigones with visible middle lamina. Dioicous. Androecia not seen. Perianth terminal on the main axis, but with lateral innovation continuing growth and becoming next main axis, the perianth looks as situated on short lateral branch, nearly tubular, appears plicate, but actually with 1–2 deep grooves starting almost from the base, suddenly contracted to densely ciliate and sometimes with slightly immersed mouth, 2.5–3.5 × 1.1–1.5 mm. Bracteole rounded, with 5–7 short lobes, densely ciliate, 120–150 µm in diameter. Bracts varying in shape and size, obovate to rounded, with 5–8 lobes densely ciliate along margins (sometimes lateral sides may be without teeth), 1.7–2.3 × 1.7–2.5 mm ( Figures 2 , 3 , 4 ).

Holotype:— CHINA. Yunnan Province: Diqing Prefecture, Shangri-La County, Xiao-Zhong-Dian Xiang, Tian-Bao Mountain , narrow valley with coniferous forest with admixture of Rhododendron and many limestone outcrops (also resulted in basic reaction of humificated soil), partly shaded Rhododendron trunk, 4,031 m a.s.l., 27°36’56”N 99°53’54”E, 16 October 2018, V.A. Bakalin & W.Z. Ma C-83-6-18 ( VBGI , duplicates KPABG , KUN ).

Paratypes:— NEPAL. Yalung valley between Lapsang and Ramze , moraine ridge in open glacier valley; amongst dwarf Rhododendron , 4,380 m a.s.l., 27°35’N 88°00’E, D.G. Long 19 September 1989, Long-17078 ( JE) . Surdscha , Kunda , NE-facing Rhododendron anthopogon Don (1821: 409–410) dwarf-scrub: ground mosses, 4,760 m a.s.l., 13 August 1986, G. & S. Miehe Miehe-8812 ( JE) .

Figures

FIGURE 2. Ptilidium himalayanum Vilnet, Bakalin & Hentschel: A—plant habit, plant with perianth, dorsal view; B—plant habit, ventral view; C–E—leaves; F–J—underleaves. Scales: a—1 mm, for A, B; b—1 mm for C–E; c—1 mm for F–J. All from C-83-6-18 (VBGI).

FIGURE 3. Ptilidium himalayanum Vilnet, Bakalin & Hentschel: A, C—female bracts; B—female bracteole; D— stem cross section; E—leaf cilia; F—midleaf cells. Scales: a—1 mm, for A–C; b—100 μm, for D–F. All from C-83- 6-18 (VBGI).

FIGURE 4. Ptilidium himalayanum Vilnet, Bakalin & Hentschel: mat, dorsal view, from C-83-6-18 (VBGI).Scale: 2 mm.