Cyrtomium remotipinnum Yan Liu & H. J. Wei 2023, sp. nov.

Cyrtomium remotipinnum Yan Liu & H.J. Wei, sp. nov. (Figs. 1, 2)

Type: — CHINA. Guangxi: Jingxi City, Ludong Town, Fujin Village, near the top of a limestone mountain, 116°17′E, 23°07′N, elev. 1030 m, 23 September 2019, She-Lang Jin & Bin Chen JSL7088 (holotype: CSH0158800!; isotypes: CSH!, GXMI!, IBK!, KUN!, MO!, PE!)

Diagnosis: — Cyrtomium remotipinnum is most similar to C. calcis in its lateral pinnae 8–15 pairs, straight in outline, 1–2 cm wide, cordate at base, and with 2–3 rows of areoles on each side of midrib, but differs by the frond more than 60 cm (vs. less than 60 cm in the latter), by the lateral pinnae remotely spaced (vs. imbricate or closely spaced), acuminate (vs. acute) at apex and with a length-width ratio of 3.5–4 (vs. less than 2.3), and by the included veinlets in larger areoles seldom fertile (vs. usually fertile).

Plants perennial, evergreen, 60–87(–99) cm tall. Frond caespitose. Rhizome erect, short, densely clothed with brown lanceolate scales. Stipe stramineous, sometimes purple at lower portion, 25–48 cm, 2–3 mm in diam. at middle, narrowly grooved adaxially, densely scaly; scales on stipe base brown, lanceolate, membranous, ca. 11–25 × 1–3.2 mm, margin minutely denticulate and slightly long ciliate, upword gradually narrowed, subulate, linear-lanceolate or filiform. Lamina ovate-lanceolate in outline, 33–51 × 9–15 cm, 1-imparipinnate, base not contracted, apex subacute. Lateral pinnae 8–15 pairs, oblong-lanceolate to ovate-lanceolate, remote, lower and middle ones (27–) 40–67 mm and (22–) 33–55 mm apart, respectively, subopposite or alternate, spreading to ascending, shortly stalked, glabrous and lustrous adaxially, abaxially with sparse hairlike scales; pinnae below middle 52–86 × 13–20(–25) mm, with ratios of length to width of 3.5–4(–4.5), base cordate, symmetrical, sometimes slightly expanded on both sides, 15–21(–27) mm wide, margins entire to repand, slightly reflexed, apex acuminate, stalk 1–2 mm long; terminal pinna ovate, with 1 or 2 connate lobes at base, (14–)20–43 × 10–34 mm; rachis stramineous, grooved adaxially, densely scaly abaxially; scales on rachis brown, linear to subulate, margins sparsely toothed; frond texture thickly leathery; venation pinnate, indistinct, lateral veins anastomosing to form 2 or 3 rows of areoles on each side of midrib, areoles along midrib prominently larger (Fig. 1. A), each often with 1 (rarely 2) included veinlet, included veinlet in larger areoles seldom fertile. Sori orbicular, subterminal on included veinlets, submarginal, in 1–3 irregular rows on each side of midrib; indusia orbicular, peltate, brown, margins irregularly toothed, usually deciduous when mature.

Spore morphology:— The spores are monolete, round in polar view and semicircular or supersemicircle in equatorial view. Spore size is 50–56 × 35–42 μm (polar axis × equatorial axis). Perispore sculpture is lophate and auriculate (Fig. 2. D).

Geographical distribution and Ecology:— Cyrtomium remotipinnum has been found in the type locality in Jingxi City and Mulun County, Guangxi Zhuang Autonomous Region, South China (Fig. 4), growing in limestone forests with lower canopy density and stronger light intensity at an elevation of 640–1030 m.

Conservation Assessments:— One population with ca. 16 individuals occurred in a mountain located just behind a village in a densely populated areas without any protection. It is facing extinction because of human disturbance. Other small populations are distributed separately in five different mountains of two protected natural reserves. A total of six populations with approximately 30–40 individuals have been found on the hillsides or tops of limestone mountains so far. Cyrtomium remotipinnum should be classified as Critically Endangered (CR C2a(i); D) according to the IUCN guidelines (IUCN 2022).

Etymology:— The specific name is derived from the Latin prefix “remoti-,” meaning “remote,” and the Latin “pinnum”, pinnae, referring to the pinnae remotely spaced.

Vernacular name:— ẆLJfiẋ (Chinese pinyin: shū yǔ guàn zhòng)

Paratypes:— CHINA. Guangxi: the same site of holotype, 16 Nov. 2013, Ping Yang 23755 (GXMI!); ibid., 27 Jan. 2016, She-Lang Jin JSL3590, JSL3591 (CSH!); ibid., 5 Feb. 2018, She-Lang Jin JSL6204 (CSH!, IBK!, KUN!); Jingxi City, Yuexu Town, Daxing Village, 15 Apr. 2019, Ping Yang et al. BL482 (IBK); Huanjiang County, Chuanshan Town, Mulun Village, 19 Apr. 2012, Ri-Hong Jiang, Jin-Cai Yang & Shui-Song Mo 11293 (IBK!); ibid., 7 Nov. 2019, Bin Chen CSH07168 (CSH!); ibid., 25 Apr. 2020. JSL7629 (CSH!); Huanjiang County, Chuanshan Town, Zhonglun Village, 7 Dec. 2020, Su-Yun Nong & Gao Xie ML355 (IBK!); Huanjiang County, Chuanshan Town, Leyi Village, 18 Dec. 2020, Su-Yun Nong ML503 (IBK!); Jingxi City, Renzhuang Town, Erlang Village, 7 Des. 2021, Su-Yun Nong & Shi-Yue Nong ZYB02710 (IBK!, CDBI!).

Additional specimens examined:— Cyrtomium calcis. Guangxi: GXMI002204, GXMI002205, IBK00446201, IBK00446202. — C. pachyphyllum. Guangxi: CSH0118498, CSH0118507, CSH0118508, GXMG0098864, GXMG0099067, GXMG0099068, GXMG0099222, GXMG0099223, GXMG0119015, GXMG0119016, GXMG0119017, GXMI055962; Yunnan: PE01000361, PE01000362, PE01000363, PE01000364. — C. shingianum. Guangxi: CSH0171860, CSH0171861*, CSH0171862*, CSH0178077, CSH0178078, CSH0178089, CSH0178090, CSH0186458, CSH0186459, GXMG0092466*, GXMG0092789, IBK00308946, IBK00431723, IBK00431724, IBK00431727; Guizhou: IBSC0762768, IBSC0763720, KUN1225629, KUN1225666, KUN1225667, PE02079203, SZG00031862; Chongqing: IMC0005740*. — C. grossum. Guangxi: CSH0171866*, CSH0178074, GXMG0112150, GXMG0168955, GXMG0177855*, GXMI056012*, GXMI062669*, IBK00198422, IBK00198423, IBK00308950, IBK00308951*, IBK00308952*, IBK00308954, IBK00308974, IBK00308978, IBK00376306, IBK00409013, IBK00431860; Guizhou: GZTM0043063, GZTM0043064, HGAS 059046, IMC0005736, KUN1225687, KUN1225693, NAS00155670, PE01000360, PE02079197, PE02079198, PE02079210, PE02079211, PE02079212, PE02079213, PE02079214, PE02109846, QNUN0028022; Hunan: HUST00005525; Chongqing: IMC0005737, IMC0005738, IMC0005739, PE01450496. — C. guizhouense. Guangxi: CSH0178057, CSH0178063, CSH0178064, CSH0178065, GXMG0112122, IBK00308948, IBK00308970, IBK00308975, IBK00361030, IBK00431726, IBK00431759, PE02019818; Guizhou: CSH0098653, CSH0098709, CSH0192336, CSH0192337, HGAS056670, IBK00446203, KUN1225632, KUN1225633, KUN1225634, KUN1225694, KUN1225695, KUN1225696, KUN1225697, KUN1225698, PE02079199, PE02079201, PE02079202, PE02079204, PE02079206.