Leptochilus ornithopus T. Fujiw.

Fujiwara, Tao, Quang, Bui Hong, Tagane, Shuichiro, Murakami, Noriaki & Oguri, Emiko, 2023, Leptochilus ornithopus (Polypodiaceae), a new hemiepiphytic fern species from central highlands of Vietnam, Phytotaxa 584 (3), pp. 149-160 : 153-155

Leptochilus ornithopus T. Fujiw. & B.H. Quang, sp. nov. ( Figs. 2–4 )

Type:— VIETNAM. Gia Lai Province: Kon Chu Rang Nature Reserve , at the edge of hill evergreen forest, 14°30´29.7″N 108°34´13.8″E, 999 m, 22 August 2019, E . Oguri , S . Tagane , K . Sugai , Y . Suyama , B. H . Quang V10634 (holotype HN!; isotypes MAK!, KAG [ KAG157385 !]) .

Diagnosis: Leptochilus ornithopus is most similar to L. digitatus and L. longipes but distinguished from both species in having ovate rhizome scales, narrowly cuneate and gradually reduced lamina bases, lanceolate lateral lobes of lamina which are widest at the proximal 1/3 or base, and the sori arranged at angles of 31–38(–40)° from midrib.

Plants perennial, evergreen, hemiepiphytic. Rhizomes long creeping, dorsiventrally flattened, 3–3.8 mm wide, dark brown, internodes 1.7–10.2 mm, densely scaly; scales ovate, 3–4.5 mm long, dark brown, basifixed, concolorous, clathrate, margins denticulate, apex long acuminate. Fronds dimorphic; stipes stramineous, with few small scales only on base; lamina simple when juvenile, trifid when mature, very rarely with an additional unilateral pinna on terminal lobe, papery, greenish gray to blue-gray adaxially, dull brownish yellow abaxially, glabrous on both surfaces, margins entire, apex acute to acuminate, base gradually reduced, decurrent. Sterile fronds with stipes 4.5–10 cm long, 1–1.4 mm in diam. at base, slightly winged to the base; lamina 13–22.5 cm long, 16.5–18.1 cm wide; terminal lobe largest, lanceolate, apex acuminate, 12.1–16 cm long, 2.2–3 cm wide, widest at proximal 1/3 or base; lateral lobes slightly smaller and narrower than terminal one, 10.7–15.1 cm long, 1.5–2.2 cm wide, widest at proximal 1/3 or base, midrib of lobes at angles of 36–42° from rachis; veins anastomosing, obscure. Fertile fronds with longer stipe than half of the total length of frond, 13.2–30.5 cm long, 1.2–2.4 mm in diam. at base, winged to the distal 1/3; laminae similar to sterile ones; veins anastomosing, lateral veins prominent adaxially, faintly visible to slightly prominent abaxially. Sori linear, on whole surface of lamina, 15–27 on each side of midrib, 1 line between each pair of lateral veins, 9.3–16 mm long, medial, at angles of 31–38(–40)° from midrib. Paraphyses absent.

Additional specimens examined:— VIETNAM. Gia Lai Province: K’Bang District, Son Lang Municipality, Kon Chu Rang Nature Reserve , 14°30′21.2″N, 108°34′11.2″E, 1000 m elev., 23 April 2022, B. H . Quang , T . D. Binh , D. T . Hoan , D. V . Hai , N. T . Cuong , V. A . Thuong , T. N . Minh BHQ801 ( HN) .

Distribution:— Vietnam (so far known only from Kon Chu Rang Nature Reserve, Gia Lai Province).

Habitat:—On tree trunks 10–100 cm above the ground in hill evergreen forests, at ca. 1000 m elev.

Etymology:—The species epithet ornithopus refers to the lamina shape of the new species, which is similar to a bird-foot.

Vernacular names:—Ráng bạc thiệt chân chim.

GenBank accession no.:—LC732070 (rbcL), LC732071 (rps4-trnS) and LC732072 (trnL -F). We sequenced material from Oguri et al. V10634.

Preliminary conservation status:—Endangered (EN). Leptochilus ornithopus was collected only from two locations, which are ca. 200 m apart, in the protected area of Kon Chu Rang Nature Reserve, at ca. 1000 m. Although it is likely to have more subpopulations in the region, the area is considered a single locality based on IUCN (2021) criteria. Based on our field observations in 2019–2022, the number of mature individuals is estimated to be less than 150. The habitat is located within the protected area of Kon Chu Rang Nature Reserve and is well-protected. Given this situation, it is assessed here as Endangered (EN), following IUCN criteria (2021).

Figures

FIGURE 2. Sporophytes of Leptochilus ornithopus T. Fujiw. & B.H. Quang. A. Sporeling showing true epiphytic habitat; B. Young sporophyte; C. Mature sporophyte; D. Creeping rhizome with clasping roots; E. feeding roots extending towards terrestrial floor, F. Habit of plant detached from soil. Red arrows indicate branching roots contacting the mineral soil; G. Young sporophyte on terrestrial floor.

FIGURE 3. Leptochilus ornithopus T. Fujiw. & B.H. Quang. A. Plant; B. Part of lamina in abaxial view, showing sori; C. Rhizome and stipes; D. Plant climbing tree trunk; E. Habitat. Photos A–C from Oguri et al. V10634, D from Quang et al. BHQ801.

FIGURE 4. Leptochilus ornithopus T. Fujiw. & B.H. Quang. A. Habitus; B. Rhizome scales; C. Scale on stipe (Drawn from Oguri et al. V10634 by T. Fujiwara).