Riccia subcrinita, Xiang & Zhang & Chen & Yu & Huang & Shen & Zhu, 2022

Xiang, You-Liang, Zhang, Zhi-Xin, Chen, Sheng-Wen, Yu, Jian-Ping, Huang, Wen-Zhuan, Shen, Chao & Zhu, Rui-Liang, 2022, Morphological and molecular evidence confirms a new species, Riccia subcrinita YouL. Xiang & R. L. Zhu) and Riccia junghuhniana Nees & Lindenb. (Ricciaceae, Marchantiophyta) new to China, Phytotaxa 531 (1), pp. 41-53 : 48

Riccia subcrinita YouL.Xiang & R.L.Zhu, sp. nov.

Diagnosis:— Similar to Riccia crinita , but differing in the smaller spore size (56–71 µm in diameter), and the spore distal surface and proximal surface alveoli without thick borders.

Type: — China, Sichuan, Kangding City , hillside of S215 Road (from Waze Town to Jiulong County), 29°33’38.02” N, 101°22’26.52” E, 3112 m, on soil, Y. L . Xiang & C . Shen 20190908-14 (holotype: HSNU) .

Plants in mats, terrestrial. Thallus small to medium-sized, 0.6–1.0 mm wide, up to 3–6 mm long; 2–3 x furcate, shortly to deeply divided; color of upper surface bluish-green, yellowish-brown to base, purple-violet on sides; dorsal furrow narrow and deep distally on dorsal surface, becoming broader and shallower towards the base; in section, thallus lobes 0.65–0.74 mm high and 2–3 times as wide as high; photosynthetic tissue of densely packed narrow columns 4–7 cells long; marginal cilia numerous, from thallus apex to base, shiny-hyaline, 0.28–0.80 mm long, not papillate; ventral scales violet-blackish with hyaline margins; rhizoids numerous and internally tuberculate.

Monoicous. Antheridial necks projecting, hyaline; sporogonium common; capsules several per plant, embedded in thallus, prominent and rupturing on the dorsal surface, with cilia protruding from apex of capsule. Spores 56–71 µm in diameter, pale brown to dark brown, distal surface usually with well-defined areolae (3.5–9.6 µm in diameter), 8–10 across diameter, with tubercules at the angles, proximal surface with similar ornamentation but alveoli with thinner walls; wing 2–3 µm wide, wing margin slightly crenulate.

Etymology: —The specific epithet consists of “sub” and “crinita”, meaning closely related to Riccia crinita .

Specimens examined: — CHINA. Gansu, Maqu County, slope near road G345 , 33°51ʹ28.14ʺ N, 101°53ʹ28.14ʺ E, 3744 m, on soil, C . Shen et al. 20200827-53 ( HSNU) ; Sichuan, Kangding City , hillside of S215 Road (from Waze Town to Jiulong County), 29°33’38.02” N, 101°22’26.52” E, 3112 m, on soil, Y. L . Xiang & C . Shen 20190908-14 ( HSNU) .

Distribution and habitat: —Known only from China. In China, it grows on moist and shady soils, associated with Aitchisoniella himalayensis Kashyap (1914: 217) , Athalamia pinguis Falconer in Anonymous (1848: 375), and Targionia hypophylla Linnaeus (1753: 1136) , from 3112 m to 3744 m.

Notes:— Riccia subcrinita is characterized by 1) monoicy, 2) thalli growing in mats, not in rosettes or hemirosettes ( Fig. 2A–B ), 3) photosynthetic tissue arranged in narrow, tightly packed vertical columns ( Fig. 2C–D ), 4) thalli 0.6–1 mm wide, 2–3 times as broad as thick in transverse section ( Fig. 2C–D ), 5) Cilia numerous, from thallus apex to base ( Fig. 2A–B ); 6) spores 56–71 µm in diameter, with complete alveoli on the distal face, 8–10 areolae across the diameter, with tubercules at the angles, but alveoli without thick borders ( Fig. 2E–F & I–L ), and 7) spore wings 2–3 µm wide, slightly crenulate ( Fig. 2G–H ).

Figures

FIGURE 2. Riccia subcrinita You.L.Xiang & R.L.Zhu. A−B. Habit in the field. C−D. Transverse section of segments. E−H. SEM micrographs of spores, E−F, distal face, G−H, proximal face. I−P. Light microscopy micrographs, I−L, distal face, M−P, proximal face. All from Y.L. Xiang & C. Shen 20190908-14 (HSNU).