Polystichum ensiforme H.Shang & R.H.Jiang, 2025

Shang, Hui, Li, Jian-Ling, Li, Zhong-Yang, Shao, Wen, Li, Fang-Hua, Li, Dong, Liu, Hong- Mei & Jiang, Ri-Hong, 2025, A new simple-lamina species of Polystichum (Dryopteridaceae) from Lingnan Region, China, Phytotaxa 704 (2), pp. 178-186 : 181-185

Polystichum ensiforme H.Shang & R.H.Jiang , sp. nov. ( Figure 2 )

Type:— CHINA. Guangxi: Guilin City, Lingui District, Nanbianshan Town , Jing’an Village , 110.23°E, 24.91°N, elev. 317 m, 24 July 2024, Hui Shang, Zhong-Yang Li & Fu-Shuai Zhang, H.Shang 3383 (holotype, CSH!; isotypes, GXFI!) .

Diagnosis:— Polystichum ensiforme is morphologically most similar to P. basipinnatum in having linear-lanceolate laminae that are simple and occasionally divided. It differs from all other cyrtomidictyoid species by rarely exhibiting pinnatifid laminae, which are confined in a few fronds bearing a whip-like apex at the rachis tip. When pinnatifid laminae are present, all segments are exclusively rounded. It further differs in having sori irregularly scattered along both sides of the rachis and distinctly thick, leathery laminae ( Figure 3 , Table 2).

Plants 30–50 cm tall, evergreen. Rhizomes short, erect, scaly at apex; scales 1–3 mm long, 0.5–2 mm wide at base, reddish-brown, ciliate at margins. Fronds tufted, linear-lanceolate; fertile and sterile fronds similar if rachis without a flagelliform tip, 25–50 cm long, mostly simple; lamina 20–30 × 2–3 cm with entire or repand to undulate margins; stipes 5–20 cm long, covered with same scales as on rhizome; fronds 35–55 cm long if rachis prolonged into a flagelliform tip, 5–25 cm long and often gemmiferous at apex, sterile; lamina 10–20 × 1.5–2.5 cm, sometimes pinnatifid with rounded segments at apex, segments 0.9–1.2 cm wide; adaxial surface sparsely covered with pale brown, fibrillose scales, scales 3–5 mm long, abaxial surface with attached scales, scales 1–1.5 mm long, 0.5–0.8 mm wide at base, ovate-lanceolate, translucent, membranous, long fimbriate at margin. Venation pinnate; midrib indistinct; veinlets 7–8 pairs, forked, basal pair not reaching edges. Sori scattered along both sides of rachis, irregularly distributed; indusia absent.

Ecology: — Polystichum ensiforme is observed growing on rocks by streamside, near small waterfalls in subtropical broadleaf forests at elevations between 200– 600 m.

Geographical distribution:— Polystichum ensiforme is endemic to China and currently only found in Guangxi (Guilin, Yangshuo, Rongxian) and Guangdong (Ruyuan, Yangchun, Zhaoqing, Jiangmen) ( Figure 4 ).

Etymology: —The species epithet is derived from the Latin, ensiform (sword-shaped), referring to sword-shaped fronds of the new species.

Vernacular name:—剑叶ª叶nfi (jiàn yè biān yè ěr jué)

Additional specimens examined:— CHINA. Guangdong: Zhaoqing City, Dinghushan, Donggangkeng, 15 September 1981, s.c. 14091 ( HUST 00003355); Lian County, 21 November 1930, Jing-Lie Zuo 22699 ( PE 00984647); Ruyuan County, Tianjingshan, 472 m, 24 July 2024, Hui Shang, Zhong-Yang Li & Fu-Shuai Zhang, H.Shang 3364, 3365, 3366 ( CSH!); Yangchun City, Heshui town, Sanyatang, 26 January 2024, Yi Huang, Shi-Wei Yao & Hui Shang, H.Shang 3325 ( CSH!). Guangxi: Guilin City, Lingui District, Nanbianshan Town, Jing’an Village, 110.23°E, 24.91°N, elev. 317 m, 24 July 2024, Hui Shang, Zhong-Yang Li & Fu-Shuai Zhang, H.Shang 3381 ( CSH!), H.Shang 3382 ( CSH!, GXFI!), H.Shang 3384 ( CSH!), H.Shang 3385 ( CSH!); Rong County, Licun town, Liuzhen, 600 m, 26 October 1955, Da-Mei Lei & Zhan-Ye Wei 40219 ( IBK 00035866); Rong County, Licun town, Taihe, 17 May 2018, s.c. 450921180517063LY ( GXMG 0203599); Guilin City, Lingui district, Nanbianshan town, 10 December 2011, Hong- Mei Liu & Ri-Hong Jiang LHM1117 ( SZG!); Yangshuo County, Jinbao Township, Sanchahekou, 287 m, 25 September 2018, s.c. 450321180925009LY ( IBK 00413906); 296 m, 6 November 2018, s.c. 450321181106026LY ( IBK 00413905); 359 m, 24 July 2024, Hui Shang, Zhong-Yang Li & Fu Shuai Zhang , H.shang 3387, 3388, 3389 ( CSH!).

Notes: —A specimen (s.c. 14091) in HUST marked " 交Dz " (exchanged) and labeled " 华南DZmffiẍãĸDzẗ ż " (Collection Records of the South China Institute of Botany) should be Polysitchum ensiforme . It was identified as " Cyrtomidictyum intergrifolium Ching et S.H.Wu " on 15 February 1982, but this name was never validly published and should be treated as a nomen nudum (Latin for 'naked name').

Figures

FIGURE 2. Polystichum ensiforme H.Shang & R.H.Jiang. A. Habit. B. Scales (from left to right): microscale from adaxial lamina, microscale from abaxial lamina, rhizome scale.

FIGURE 3. Morphological comparison between Polystichum ensiforme (top) and P. basipinnatum (bottom): A. & D. Habit, B. & E. Portion of frond, C. & F. Portion of lamina showing sori (photo credits: A & C by Z. Y. Li; B by W. Q. Wang; D by X. L. Zhou; E & F by K. Ye).

FIGURE 4. Distribution of three simple-lamina cyrtomidictyoid fern.