Leptochilus gracilis
Plants perennial, evergreen, lithophytic. rhizome long creeping, ca. 1.5–2.5 mm in diam., dorsiventrally flattened, sparsely scaled, dark brown when dry, with a few short phyllopodia and many roots; cross section of rhizome with 5 vascular bundles, 3 are big and 2 are small, sclerenchyma strands 35–50. Apex of rhizome and basal petiole densely scaly, scales subulate-lanceolate, (1–)1.5–2.5 mm, dark brown, basifixed, concolorous, clathrate, margin entire or sparely denticulate, apex acuminate; petiole scales filiform-subulate, (0.7)1–1.3 mm, differ in size, membranaceous, dark brown, margin entire, apex caudate. Frond monomorphic, (11–)14–20 cm tall, (5–)6.5–11 cm wide; petiole stramineous, (3–)4.5–8 cm long, (0.7–)1–1.2 mm wide, with a few scales on base, without groove, slightly winged at distal part. Lamina triangular-ovate, deeply pinnatifid, margins entire, (8–)10–13 cm long, 6–11 cm wide, widest at base of lamina, papery, greenish brown when dry, glabrous adaxially, with microscales abaxially, microscales 0.5–1 mm long, ca. 0.15–0.35 mm wide; lobes 1–2 pairs, terminal lobe largest, narrowly lanceolate, sloping forward, apex acuminate, 3.5–9.5 cm long, 0.4–1.2 cm wide, basal portions of lobes slightly narrowed, ascending upward, midrib of lobes at angles of 45–60 degree with rachis, distal pairs of lobes narrowed, ca. 1/2 to 4/5 as long as basal ones, opposite or slightly alternate, lateral lobes distant with each other in 1.5–3.0 cm; rachis stramineous, obviously winged, 9–12 mm wide at the distal part including the laminal wings, 1–3 mm at base. Veins anastomosing, invisible. Sori linear, (2–)5–7(–9) on each side of lobe, 5–8 mm long, 0.8–1.2 mm wide, medial, at angles of 35–45 degree with midribs, centers ca. 5-8 mm apart from one another. Paraphyses absent.
Critical Endangered
Leptochilus gracilis is resolved as sister to a cultivation identified as L. aff. ellipticus(Chen C.C. 1065, cultivation in Xishuangbanna Tropical Botanical Garden, specimen in H), and they together form a distinct subclade being sister to other species of the L. ellipticus clade.
Currently, Leptochilus gracilis is only found in Jinping County, Yunnan Province, and may represent a species endemic to Yunnan, China
Grow on limestone rocks in the slightly disturbed forests, at elevations between 1700 and 1900 m.