Leptochilus sinovietnamica Liang Zhang, N.T. Lu & Li Bing Zhang

Zhang, Liang, Lu, Ngan Thi, Zhou, Xin-Mao, Zhou, Zhuo, Thepkayson, Khamphanh, Luong, Thien Tam & Zhang, Li-Bing, 2024, Exploring the diversity of the Java fern genus Leptochilus (Polypodiaceae) in the Indo-Burma Biodiversity Hotspot, Phytotaxa 659 (3), pp. 213-235 : 228-229

9. Leptochilus sinovietnamica Liang Zhang, N.T. Lu & Li Bing Zhang , sp. nov. ( Fig. 11 ).

Type: CHINA. Yunnan: Hekou, Nanxi Town, Anjiahe, elev. 366 m, 22.69°N / 103.92°E, on limestone rocks beside a stream in forest, 31 August 2019, Liang Zhang, Zhen-Long Liang, Xiang-Li Yue & Zi-Yu Ye 3040 (holotype KUN-1576330!, isotype KUN-1576329!).

Diagnosis: Leptochilus sinovietnamica is characterized by its large habit, fronds 60–100 cm long, lamina thinly chartaceous, and lobes large, 3.5–5.5 cm in width.

Plants perennial, evergreen. Rhizome creeping, ca. 0.6–1.1 cm in diam., dorsiventrally flattened, scaly, with many short roots; scales, appressed, slightly spreading at rhizome apex, irregularly ovate, clathrate, thickly membranous, margins entire or sparely denticulate, brown, (0.8–)1.8–3.5 (4.6) × 0.4–1.2 mm. Fronds monomorphic or sometimes slightly dimorphic, 0.5 to 1.2 cm distant, (30–) 60–100 cm long; petioles stramineous, (16–) 35–44 cm long, ca. 2.4–3.1 mm in diam. at middle, wingless; rachises wingless, and only slightly winged at distal rachis at the connecting part between rachis and lobe. Laminae broadly elliptic, deeply 1-pinnatifid, (18–)31–56 × 30–50 cm, widest at middle or below middle of laminae, thinly chartaceous, brown when dry, glabrous, margins of lobes entire, slightly repand. Lobes (1–)2–6 pairs, lanceolate, apex acuminate, 15–26 × (2.1–) 3.5–5.5 cm, basal portions of lobes narrowed, ascending upward, midribs of lobes at angles of 41–54 degree with rachis, distal pair of lobes slightly narrowed, alternate or nearly opposite, lobe base ca. 2.5–4.9 cm distant with each other. Midribs distinctly raised, veins visible. Sori linear, 18–25 on each side of midrib, centers ca. 5–8 mm apart from one another, 1.3–2.8 × 0.5–0.9 mm.

Additional specimens examined: CHINA. Yunnan: Jinping, Mengla, Jiushiliang , elev. 650 m, on rock in limestone mountains, 25 August 1962, Sugong Wu 4044 ( KUN!, PE!) . VIETNAM. Bac Kan: Na Ri District, An Tinh Community, Tham Mu , 300–500 m, 5 December 2013, Li-Bing Zhang, Liang Zhang & Ngan Thi Lu 6711 ( CDBI!) ; Hoa Binh: Tan Lac District, Tam Son Community, Ngoc Son Ngo Luong Nature Reserve , 840 m, 20.53°N / 105.18°E, 22 November 2013, Li-Bing Zhang, Liang Zhang & Ngan Thi Lu 6377 ( CDBI!) ; Quang Binh: Phong Nha Ke Bang National Park, 27km of #20 Road , 400 m, 17.44°N / 106.24°E, near rock in forest, 07 November 2014, Li-Bing Zhang, Liang Zhang & Ngan Thi Lu 7365 ( CDBI!, VNMN) .

Distribution and habitat: Leptochilus sinovietnamica is found in the southern region of Yunnan, China, as well as in central and northern Vietnam. This species is observed growing on or in proximity to rocks in a limestone mountain.

Etymology: The specific epithet, sinovietnamica, indicates that the species is currently known distributed in China and Vietnam.

Note: Leptochilus sinovietnamica is distinguished by having the large fronds up to 90 cm long and 3–4 pairs of lateral lobes. The sample labeled as “Li-Bing Zhang et al. 6711”, featuring one pairs of lobes, presents an exception within the species. To fully characterize the species in terms of its morphology, additional morphological studies should be conducted by incorporating a broader range of sequenced materials.

Figures

FIGURE 11. Leptochilus sinovietnamica Liang Zhang, N.T. Lu & Li Bing Zhang,—A& B.Abnormal individuals with one pair of lobes.— C. Portion of adaxial lamina.—D. Upper portion of abaxial lamina showing sori.—E. Portion of abaxial lamina lobe.—F. Rhizome.—G. Rhizome scales. Photo credit: Liang Zhang.