Lepisorus youxingii R.H.Jiang & X.C.Zhang, 2020

Jiang, Ri-Hong, Wang, Ya-Rong & Zhang, Xian-Chun, 2020, Lepisorus youxingii (Polypodiaceae), a new fern species from Guangxi, China, Phytotaxa 437 (2), pp. 97-104 : 102

Lepisorus youxingii R.H.Jiang & X.C.Zhang , sp. nov. ( Figs. 2 & 3 ).

Diagnosis: —The new species is similar to Lepisorus thunbergianus , L. oligolepidus and L. lewisii , but differs in rhizome scales (brown, iridescent, transparent, lanceolate with broadly ovate base, margin denticulate, and apex long acuminate), in laminae (lanceolate, widest at third from the length, with base attenuate, decurrent, margin narrowly callose, and apex long caudate), and in paraphyses (brown, orbicular, with margin denticulate, and lumina transparent).

Type: — CHINA. Guangxi: Rongshui County, Mt. Yuanbaoshan, epiphytic on tree trunks, elev. ca. 1900 m, 12 August 2019, R. H.Jiang et al. 13004 ( PE!).

Plants epiphytic, 15−40 cm tall. Rhizomes long−creeping, 1.8−3 mm in diam., densely scaly, sometimes naked when old; scales spreading, brown, iridescent, transparent, lanceolate with broadly ovate base, 3.5−8.5 × 0.5−2 mm, clathrate, margin denticulate, apex long acuminate, lumina large and transparent, isodiametric at base, and oblong at apex. Fronds remote, up to 2 cm apart; stipe straw−colored, 2−5 cm, 0.8−1 mm in diam.; lamina abaxially grayish green, adaxially dark green when dried, lanceolate, 15−35 × 1.5−3 cm, widest at third from the length, leathery, adaxially glabrous, abaxially sparsely scaly, scales brown, lanceolate with broadly ovate base, 1−2 × 0.2−0.4 mm, transparent, clathrate, margin denticulate, apex long acuminate; lamina base attenuate, decurrent, margin narrowly callose, apex long caudate; costa raised on both sides, veinlets obscure. Sori on distal half of lamina, slightly closer to costa, orbicular or elliptic, 2.5−4 mm in diam.; paraphyses brown, orbicular, 0.15−0.35 mm in diam.; lumina transparent.

Etymology: —The specific epithet is dedicated to Prof. You-Xing Lin, who contributed to the account of Lepisorus for Flora Reipublicae Popularis Sinicae ( Lin 2000).

Distribution and habitat:— Lepisorus youxingii is endemic to Guangxi, southern China, distributed in Mt. Yuanbaoshan and Mt. Gunbeilaoshan, Rongshui County. It is epiphytic on tree trunks at elevation of 1700–1900 m.

Conservation status:— Lepisorus youxingii has been found in two mountains of Rongshui County, Guangxi. This species is in protected area with more than 250 mature individuals. Therefore, it can be classified as LC (Least Concern) according to the IUCN criteria ( IUCN 2019).

Additional specimens examined (paratypes):— CHINA. Guangxi: Rongshui County, Mt. Yuanbaoshan , epiphytic on tree trunks, elev. ca. 1700 m, 12 August 2019, R. H.Jiang et al. 13003 ( PE!) ; Mt. Gunbeilaoshan , elev. 1900 m, 14 October 2011, R. H.Jiang et al. JRH2503 ( IBK!) .

Figures

FIGURE 2. Lepisorus youxingii R.H.Jiang & X.C.Zhang. A. Habitus; B. Rhizomes; C. Part of lamina; D. Rhizome scales; E. Paraphyses (Drawn by W. H. Lin from R.H. Jiang et al. 13004, PE).

FIGURE 3. Lepisorus youxingii R.H.Jiang & X.C.Zhang.A. Habitat; B. Plant, showing lamina morphology; C. Part of lamina in abaxial view, showing sori; D. Plant; E. Rhizome, showing scales; F. Part of lamina in abaxial view, showing sori; G. Part of lamina in adaxial view; H. Paraphyse; I–J. Rhizome scale.