Hymenasplenium sinense K.W. Xu, Li Bing Zhang & W.B.Liao, 2018

Hymenasplenium sinense K.W. Xu, Li Bing Zhang & W.B.Liao View in CoL , sp. nov. Figs. 12 View FIGURE 12 , 13 View FIGURE 13 .

Type:— CHINA. Guizhou: Songtao Xian, Lengjiaba, near the confluence of the Xiaohe and Dahe rivers, Northeast Fanjingshan Mountain range , elev. 820–1120 m, on wet rocks and on rock ledges near river in forest, 5–9 October 1986, Sino-American Guizhou Botanical Expedition no. 2207 (holotype MO!) .

Diagnosis:— Hymenasplenium sinense is most similar to H. obliquissimum ( Hayata 1914: 230; Sugimoto 1966: 406) in having rhizome scales dense, fronds membranous and sub-translucent, and sori located in the middle or apex of pinnae, but the former has rhizome scales brown, pinnae 15–25 pairs, laminae ovate, and marginal teeth of the pinnae not retuse, and veins terminating in marginal teeth, while the latter has rhizome scales black, pinnae more than 25 pairs (often more than 30 pairs), laminae lanceolate, and marginal teeth of the pinnae retuse, and veins terminating below the tooth notches.

Plants perennial, evergreen, 15–30 cm tall. Rhizomes long creeping, 1.5–2.5 mm in diam., apex densely scaly, scales grayish brown, narrowly triangular, margins nearly entire, 0.4–0.5 × 1–1.8 mm; root brown when dried, slender, up to 5 cm long, ca. 0.2 mm diam, root glabrous or covered with yellow woolly indumenta, phyllopodia distinct, ca. 2 mm tall, up to 10 mm apart. Fronds membranous, thin to translucent, brown-green when dry; petioles shiny, castaneous, glabrous. Laminae narrowly ovate, 1-pinnate, 15–25 × 2–5 cm, base slightly reduced, widest near base, gradually narrowing toward apex, apex acute or acuminate; rachises 0.5–1 mm in diam., subglabrous, castaneous, adaxial side grooved and with 2 green narrow wings. Pinnae shortly stalked to almost sessile at apex, 15–25 pairs, subopposite or alternate, trapeziform or falcate, (middle pairs) 1.5–3 × 0.5–0.8 cm, up to 3 mm apart, base asymmetrical, acroscopic side truncate and subparallel or forming an angle less than 15° with rachis, basiscopic side cuneate, with ca. 10 mm absent (calculated from the base to the first tooth appearing in the margin of basiscopic side), acroscopic margins serrate, teeth not retuse, acute or obtuse, basiscopic margins crenate-sinuate, teeth obtuse and not retuse, apex subacute to obtuse. Veins visible on both sides of pinnae, stramineous, lateral veins visible on both sides of pinnae, green, forking and terminating in marginal teeth, 2–4 basal basiscopic veins lacking. Sori linear, 1–3 mm long, basal on subtending vein and appearing subcostal, 2–5 on acroscopic side and 2–3 on distal basiscopic side of the pinnae in the middle part of the laminae, centers 1–2 mm apart from one another; indusia brown, linear, membranous, entire, opening toward costa.

Geographical distribution:— Hymenasplenium sinense is widely distributed in the central, southern, and southwestern China. It might also occur in Thailand. Further studies are needed for material from India, Indonesia, Japan, Nepal, and Vietnam.

Ecology:— Hymenasplenium sinense was observed to grow on wet rocks near or in streams in forests.

Etymology:—The species epithet is based on the Latin, Sina , China, and the Latin suffix, -ense, of origin, referring to where the type was collected from and the current major known distribution of the species in China.

Vernacular name:—ϕṣůďäffǎ (zhong hua mo ye tie jiao jue).

Taxonomic notes:—Due to the previous confusion with Hymenasplenium obliquissimum , H. sinense has not been known by modern pteridologists. Lin and Viane (2013) assigned material of this species to H. obliquissimum whose type is from Arisan, Taiwan. However, H. obliquissimum sensu Lin and Viane (2013) has different morphology from its type and should represent H. sinense in our delimitation.

Additional material examined:— CHINA. Yunnan: Pingbian Xian, Daweishan , on wet rocks near stream, 29 October 2015, Xu PB 001 (SYS!) ; Guangxi: Rongshui Xian, Yuanbaoshan , 27 November 2015, Xu GX 018 (SYS!) ; Jiangxi: Suichuan Xian, Daijiapu Xiang, Qianmo Cun , 26°17’39.57”N, 114°3’45.24”E, 880 m, 17 May 2016, Kewang Xu 134 (SYS!) GoogleMaps ; Jingangshan, Jingzhushan , 28 June 1965, Lai et al. 4281 (IBK!) .