Leptochilus multilobus Liang Zhang & X.M. Zhou

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 : 225-227

7. Leptochilus multilobus Liang Zhang & X.M. Zhou , sp. nov. ( Fig. 9 ).

Type: CHINA. Xizang: Medog County, Beibengxiang, Aniqiao to #3 bridge, elev. 1085 m, 29.32°N / 95.16°E, on wet rocks at forest margins, 17 October 2017, Liang Zhang, Wen-Bin Ju & Heng-Ning Deng 2193 (holotype KUN-1576328!, isotype KUN-1576327!).

Diagnosis: Leptochilus multilobus can be distinguished from other species by its lobes up to 15 pairs, sori oblong to shortly linear, and length of sori approximately half that of the distance from the midrib to the lobe margins.

Plants perennial, evergreen. Rhizome creeping, ca. 2.9–4.2 mm in diam., dorsiventrally flattened, densely scaled, with many short roots; scales brown, clathrate, membranous, margins entire or sparely denticulate, 0.8–3.2 × 0.6–1.5 mm. Fronds monomorphic, 0.4 to 0.6 (2.5) cm distant, 32–52 cm long; petioles stramineous, 13–26 cm long, ca. 1.4– 2.1 mm in diam. at middle, slightly winged at distal part; rachis narrowly winged, 2.1–2.5 mm wide at the distal part, 0.7–1.1 mm at base. Laminae elliptic, deeply 1-pinnatifid, 20–27 × 9–12 cm, widest at middle of laminae, chartaceous, brown when dry, glabrous, margins of lobes entire. Lobes 12–15 pairs, narrowly lanceolate, apex acuminate, 6.5–7.0× 0.7–0.9 cm, basal portions of lobes distinctly narrowed, ascending upward, midribs of lobes at angles of 42–68(–77) degree with rachis, distal pairs of lobes narrowed, mostly opposite, lobe base ca. 1.1–1.7 cm distant with each other. Midribs slightly raised, lateral veins invisible. Sori oblong or shortly linear, (4–)7–11 on each side of midrib, 1.8–4.0 × 0.5–1.1 mm, centers ca. 3–6 (–9) mm apart from one another.

Additional specimens examined: CHINA. Xizang: Medog County, Dexingxiang, on the way to Deguo village , elev. 935 m, 29.36°N / 95.34°E, on a wet cliff near waterfall, 23 June 2021, Liang Zhang, Xia Wan, Jian-Jun Yang, Wang-Lin Zhao 4455 ( KUN) ; Medog County, Beibengxiang, Aniqiao to #3 bridge, elev. 1085 m, 29.32°N / 95.16°E, on a wet rock at forest margins, Bo Xu et al. YLZB2004 ( CDBI!) .

Distribution and habitat: Leptochilus multilobus is currently only known from Medog, a remote county in Tibet, China. Two large populations, approximately 20 km apart in an air distance, have been discovered. One population found in Beibengxiang has been destroyed due to road construction, while the other population, which has about 30 individuals, is in good condition. The species is restricted in rocky areas near streams or waterfalls, and high humidity is crucial to maintaining a healthy population.

Etymology: The species epithet is derived from the Latin words multi-, multiple, and -lobus, lobes. This epithet refers to the numerous pairs of lobes present on each lamina.

Note: Leptochilus multilobus resembles species in the L. ellipticus clade by having pinnatifid laminae ( Zhang et al. 2019), while differs them in having a great number of lobes and oblong to shortly linear sori. Phylogenetically, L. multilobus was resolved as a member in the Colysis clade ( Fig. 1 ), which is composed of those with simple and entire laminae, making L. multilobus a unique species in the genus.

Figures

FIGURE 1. Phylogeny of Leptochilus based on six plastid markers (modified from Zhang et al. 2024). Orange color indicates the new species described here.

FIGURE 9. Leptochilus multilobus Liang Zhang & X.M. Zhou,—A. Habitat.—B. Abaxial lamina and fiddlehead.—C. Portion of abaxial lamina showing sori.—D. Rhizome.—E. Portion of adaxial lamina. Photo credit: Liang Zhang.