Polystichum gonggashanense H.S.Kung & Li Bing Zhang ex H.He & Li Bing Zhang, 2022

He, Hai & Zhang, Li-Bing, 2022, Polystichum gonggashanense (Dryopteridaceae): a new fern from Sichuan, China, Phytotaxa 559 (2), pp. 207-212 : 207-210

Polystichum gonggashanense H.S.Kung & Li Bing Zhang ex H.He & Li Bing Zhang , sp. nov. ( Figs. 1 & 2 ).

Type:— CHINA. Sichuan: Luding County, Mt. Gongga (Minyar Gonkar), Hailuogou , #3 rd Camp to Chengmendong , elev. ca. 2950 m, 20 July 2010, Hai He 1190 (HG037) (holotype CDBI; isotypes CDBI, CTC, MO) .

Diagnosis:—The new species is most similar to Polystichum sinense (Christ in Baroni & Christ 1901: 289) Christ (1905: 30), but the former has an oblong-lanceolate lamina with the lower portion only slightly contracted toward the lamina base, petiole scales that are blackish brown, and rachis scales that are narrowly lanceolate. In contrast, the latter has an elliptic-lanceolate lamina with the lower portion substantially contracted toward the lamina base, petiole scales that are brown, and broad-lanceolate rachis scales.

Description:—Plants 73–87 cm tall. Rhizomes erect; fronds cespitose. Petioles 24–33 cm long, 3–5 mm in diam., stramineous; large scales ovate or ovate-lanceolate often 20 mm long, 8.5 mm wide, acute at apex, ciliate or subentire on margins, the proximal ones uniformly blackish brown or brown, thick chartaceous, distally transitioning gradually to bicolorous with paler-colored margins, then to concolorous light yellow-brown and membranous; small scales linear to lanceolate. Laminae oblong-lanceolate, 49–57 cm long, 16–21 cm wide, elongated-acuminate or caudate at apex, lower portion sterile, bipinnate. Rachises ca. 2 mm in diam.; rachis scales narrow-lanceolate, brownish, long-acuminate at apex, subentire on margins, spreading or reflexed. Pinnae 22–31 pairs, spreading, alternate, short-petiolate, middle pinnae 1.5–2.5 cm apart, 4.5–10 cm long, 1.9–2.3 cm wide, lanceolate, apex acuminate or caudate, base inequilateral, 1-pinnate; basal pinnae slightly shorter, 4.5–7.0 cm long, with 7–11 pairs of free pinnules; pinna rachis with linearlanceolate small scales (these denser abaxially), ca. 5 mm long. Pinnules 13–16 pairs, sessile, spreading, herbaceous, deltoid-ovate, 12–13 mm long, 4.1–5.5 mm wide, auriculae deltate, base cuneate and slightly adnate (only the distal third of the pinna), apex acute, margins aristate-dentate, with 1.5–3.5-mm-long linear microscales on both surfaces, basal acroscopic pair the longest and lobed; veins 5–7 pairs per pinnule, dichotomous, slightly visible. Sori light brown, one row on each side of midrib, close to midrib; indusia peltate, rotund, membranous, margins subentire.

Etymology:—Derived from gonggashan in Chinese pinyin, meaning Mt. Gongga (Minyar Gonkar).

Vernacular name:— ūḝ山φƦ (gong ga shan er jue).

Distribution:—It was found on the eastern, southeastern, and western slopes of Mt. Gongga in Jiulong, Luding, and Kangding counties, Sichuan Province, Southwest China, with elevational range of 2500–3200 m.

Conservation assessment:—Based on thorough explorations by Kai-Yong Lang et al. in 1982, by L-BZ in 1989, 1990, and 1993, and by HH in 2010, only four very small populations each with a few individuals were found.All these populations are in high elevations of the same mountain. The expansion of the touristic facilities and global warming threaten the survival of Polystichum gonggashanense and the population in the first locality already disappeared. We suggest that the status of Polystichum gonggashanense be listed as CR (Critically Endangered) following IUCN criteria ( IUCN 2019).

Additional specimens examined (paratypes):— CHINA. Sichuan: Luding County, Mt. Gongga (Minyar Gonkar), Hailuogou , elev. ca. 2980 m, 29 October 1989, Li-Bing Zhang 169 (KUN, PYU); ibid., 1990, Li-Bing Zhang 911 (CDBI); Jiulong County , Hongba , elev. ca. 2500 m, on forest margin, October 1990, Li-Bing Zhang 2786 (CDBI, PYU); Kangding County , Liuba , elev. ca. 3200 m, July 1982, Kai-Yong Lang et al. 752 (KUN, PE); same town, 1990, Li-Bing Zhang s.n. (CDBI, PYU) .

Taxonomic notes:—We examined all specimens available at CTC and it appears that all sporangia were dehisced. There were fewer than 32 spores per sporangium and most sporangia had only 10–20 spores upon examination. It is possible that the new species is apomictic.

In middle to high elevations of the Sino-Himalayan region species of Polystichum are common, most of which belong to P. sect. Hypopeltis ( Michaux 1803: 266) T. Moore (1857: 84) taxonomically ( Zhang & Barrington 2013). The taxonomy of this section is difficult partially because the species are over-described ( Zhang & Barrington 2013). Between 1983 and 1993, seven “species” were described for P. sinense alone (Ching in Wu 1983, Ching & S.K.Wu in Wu 1983, Yang 1992) including P. alatawshanicum Chang Y. Yang (1992: 302) , P. atuntzeense Ching in Wu (1983: 231), P. austrotibeticum Ching & S.K.Wu in Wu (1983: 233), P. decorum Ching & S.K.Wu in Wu (1983: 229), P. ellipticum Ching & S.K.Wu in Wu (1983: 233), P. lhasaense Ching in Wu (1983: 230), and P. parasinense Chang Y. Yang (1992: 302) . Relevant molecular data for Polystichum so far have not yet been based on extensive taxon sampling of P. sect. Hypopeltis ( Liu et al. 2007, Le Péchon et al. 2016a, 2016b). Polystichum gonggashanense has not been described so far partially because it is a rare species endemic to a small area in Mt. Gongga.

Notably, Polystichum decorum , thought as conspecific with P. gonggashanense by the reviewers of Acta Botanica Yunnanica as stated in the introduction, is a synonym of P. sinense . The distinction between P. gonggashanense and P. sinense is not neglectable in the color of petiole scales, the lamina shape, and the shape of rachis scales (see above; Table 1 ).

In addition to Polystichum sinense , P. gonggashanense is also similar to P. haleakalense Brackenridge (1854: 204) and P. kangdingense H.S.Kung & Li Bing Zhang ex Li Bing Zhang (2012: 58) in having bipinnate laminae, ovatelanceolate petiole scales, lanceolate rachis scales, and linear microscales. These four species are compared with one another in Table 1.

Figures

FIGURE 1. An illustration of Polystichum gonggashanense.—A. Habit.—B. Pinna.—C. Petiole scales.—D. Rachis scales.—E. Microscales.—F. Indusium (based on Li-Bing Zhang 169; drawn by Jian Chen).

FIGURE 2. A color plate of Polystichum gonggashanense.—A. The highest peak of Mt.Gongga where the new species was discovered.— B. Habit.—C. Lower portion of petiole showing blackish brown scales.—D, E. Portions of adaxial pinnae showing scales.—F. Portion of abaxial pinna showing sori and scales.