Leptochilus daklakensis Liang Zhang, X.M. Zhou, T.T. Luong & Li Bing Zhang, 2024

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 : 219-220

2. Leptochilus daklakensis Liang Zhang, X.M. Zhou, T.T. Luong & Li Bing Zhang , sp. nov. ( Fig. 4 ).

Type: Vietnam. Đắk Lắk: Chu Yang Sin National Park, Sub-area 1351, 1080–1250 m, 12.41°N / 108.37°E, on rocks, small branch of Krông Kmar River, 30 October 2015, Li Bing Zhang, Xin Mao Zhou, Thien Tam Luong, Minh Tri Dang & Bich Ha Duong 8944 (holotype CDBI!, isotypes PHH, MO!).

Diagnosis: Leptochilus daklakensis is distinguished from other species by its dimorphic fronds, fertile fronds two times longer than sterile fronds, sterile fronds with broadly winged petioles, petioles of fertile fronds four times longer than fertile laminae, and apex of fertile laminae abruptly narrowed.

Plants perennial, evergreen, lithophytic. Rhizome long creeping, ca. 2.6–3.5 mm in diam., dorsiventrally flattened, densely scaly, scales lanceolate, 1.2–3.5 × 0.4–0.7 mm, dark brown, basifixed, concolorous, clathrate, margin entire or sparely denticulate, apex acuminate. Fronds dimorphic, fertile fronds usually much longer than sterile fronds, or rarely the same length as sterile fronds. Sterile fronds (6–) 18–22 cm tall, sessile or shortly petiolated; laminae elliptic-lanceolate, base gradually narrowed, apex acuminate or cuspidate, (6–) 18–22 cm long, 2.9–3.2 cm wide near middle, chartaceous, glabrous; petioles short, stramineous, grooved adaxially, 1.1–1.2 mm in diam., 0.3–0.7 cm long, petiole base scaly; scales similar to rhizome scales but smaller, 1.3–1.5 × 0.4–0.5 mm. Fertile fronds (16) 35–41 cm tall, petiole much longer than lamina; laminae deltate-lanceolate, margins entire, base cuneate, apex long acuminate, 5.4–9.0 cm long, 2.2–4.1 cm wide bellow middle part, chartaceous, glabrous; petioles stramineous, grooved adaxially, 0.9–1.1 mm in diam., (11–) 27–32 cm long. Veins anastomosing, distinct adaxially and abaxially, veinlets visible. Sori linear, reach lamina margins, ca. 0.8 mm from margins and 1–2.5 mm from midrib, 15–23 on each side of midrib, 1.2–2.9 cm long, 0.4–0.6 mm wide when mature, at angles of 42–47 degree with midribs, centers ca. (1–)1.5–3.0 mm apart from one another.

Distribution and habitat: Leptochilus daklakensis is currently known from south Đắk Lắk Province, Vietnam. The species was observed only growing on rocks in rainforests.

Etymology: The species epithet is from the Vietnamese name, daklak, the name of the province in South Vietnam where the type was collected, and the Latin suffix -ensis, of origin or place.

Notes: Leptochilus daklakensis closely resembles L. ovatus but differs the latter in having broadly winged petioles (vs. narrowly wringed petioles, or sometimes petioles wingless), apex of fertile laminae abruptly narrowed (vs. apex of fertile laminae rounded or gradually narrowed). Phylogenetically, L. daklakensis was resolved as an isolated lineage quite distant from L. ovatus in the L. Colysis clade.

Figures

FIGURE 4. Leptochilus daklakensis Liang Zhang, X.M. Zhou & Li Bing Zhang,—A, B, C. Habit.—D.Abaxial view of fertile lamina.— E. Rhizome scales. Photo credit: Xin-Mao Zhou.