Hymenasplenium hastifolium Ke Wang Xu, Li Bing Zhang &W.B.Liao, 2018

Xu, Ke-Wang, Zhou, Xin-Mao, Zhang, Li-Bing & Liao, Wen-Bo, 2018, Hymenasplenium hastifolium sp. nov. (Aspleniaceae) from a karst cave in western Guangxi, China, Phytotaxa 333 (2), pp. 281-286 : 281-284

Hymenasplenium hastifolium Ke Wang Xu, Li Bing Zhang &W.B.Liao , sp. nov. ( Figs. 1 & 2 )

Diagnosis:— Hymenasplenium hastifolium somewhat resembles H. ikenoi ( Makino 1899: 130) Viane in Lin & Viane (2013: 309) and H. cardiophyllum ( Hance 1883: 268) Nakaike (1997: 419) in having laminae simple and rhizomes long-creeping, but the former has laminae hastate with two long auricles at the base, midribs trichotomous, and sori occurring in two rows along the midribs of the lamina base, while the latter two both have laminae ovate without auricles at the base, midribs simple, and sori occurring in one row at the lamina base.

Type:— CHINA. Guangxi: Baise City, Pingguo County, Jiucheng Zhen, Juyou Cun, elev. 260 m, 23°34.200′N, 107°39.733′E, in evergreen broadleaved forest at a cave entrance of limestone mountain, 13 April 2016, Ke-Wang Xu & Ping Yang XKW282 (holotype SYS!, isotypes MO!, SYS!).

Plants perennial, evergreen, up to 45 cm tall. Rhizomes long creeping, 0.1–0.5 cm in diam., with scales and some yellowish brown hairs; scales blackish brown, lanceolate, ca. 1.5 × 0.36 mm, margins sparsely toothed, and caducous on older rhizome parts. Fronds well separated, simple, thinly papery, green or dark green, dark to brownish green when dry, subglabrous; stipe shiny, castaneous to purplish black, 15–30 cm, 0.1–0.2 mm in diam., terete but with adaxial groove, base with fibrous scales and pale yellow hairs, scales ca. 1.8 × 0.072 mm; lamina simple, hastate, 8–15 cm long, with linear black scales on abaxial side, base with two auricles, 1.2–2.5 mm wide, 0.9–1.8 cm wide in the middle, apices acute to acuminate, margins entire or shallowly sinuate. Veins visible adaxially and slightly obscure abaxially; midrib trichotomous, shiny and castaneous to ca. middle of leaf; lateral veins slender, and hardly visible on abaxial side near margin; vein ends free. Sori linear, usually solitary on acroscopic veins, rarely opposite along 3-veins; indusia persistent, light brownish, linear, thinly membranous, entire.

Distribution and ecology:— Hymenasplenium hastifolium is currently known only from one locality in Juyou Cun, Jiucheng Zhen, Pingguo County, Baise City, western Guangxi, China. The new species was observed to grow on limestone walls/floor at a cave entrance at an elevation of 260 m in subtropical evergreen broadleaved forest on a karst mountain.

IUCN Red List category:— Only one population with about 50 plants is known from in an area of ca. 5 × 5 m in the type locality and the survival of this species is threaten by flooding, grazing and farming. The status of the new species clearly should be CR-Critically Endangered category based on current information available and following IUCN (the International Union for Conservation of Nature and Natural Resources) guidelines (IUCN 2015).

Etymology:— Based on the Latin prefix, hasti-, hastate, and the Latin suffix, -folium, of leaf, referring to the hastate shape of the lamina of the new species.

Vernacular name:— We would like to give it a Chinese name, Jǐyè xìxīnjué (Ȓďȁ÷ů) to reflect its distinctly hastate shape of its laminae.

Figures

FIGURE 1. Hymenasplenium hastifolium Ke Wang Xu, Li Bing Zhang &W.B.Liao—A. The limestone mountain and vegetation, red circle showing the site where the new species was discovered.—B. Habit.—C. Special variation of lamina.—D.Abaxial view of lamina.— E. Adaxial view of lamina.—F. Lamina base showing two rows indusia on both sides of auricles’ midrib (A–E: Photographed by Ke-Wang Xu).

FIGURE 2. Hymenasplenium hastifolium Ke Wang Xu, Li Bing Zhang &W.B.Liao—A. Habit.—B. Lanceolate scales from rhizomes.— C. Linear scale from base of stipe. (Drawn by Ke-Wang Xu based on the isotype at MO).