Arachniodes mira H.J. Wei, 2025

Wei, Hong-Jin, 2025, Arachniodes mira (Dryopteridaceae), a new species from southeastern Yunnan, China, Phytotaxa 706 (2), pp. 148-154 : 150-153

Arachniodes mira H.J. Wei , sp. nov. ( Figs. 1 , 2 ).

Type:— CHINA. Yunnan: Xichou County, Xinjie Town, Anle Village , in a slope of forest margins, 104°40′E, 23°14′N, elev. 1230 m, 19 Nov. 2021, She-Lang Jin JSL8460 (holotype: CSH0195555 !; isotypes: CSH!, IBK!, KUN!, PE!) .

Diagnosis:— Arachniodes mira is unique by the frond varying from imparipinnate to bipinnate. Its imparipinnate form resembles A. neopodophylla , but differs by the lower pinnae with one or more free lobes (vs. with repand, crenate or coarsely toothed margins in the latter), and with sori not close to the costa (vs. with sori close to the costa), typically presenting a sterile zone on both sides of costa (vs. often leaving a broad marginal sterile zone).

Description: Plants perennial, evergreen. Rhizome creeping, 4–6 mm in diam., apex densely covered with scales; scales dark brown or blackish brown, narrowly lanceolate, membranous, 7–10 × 0.4–0.9 mm, margin entire, sometimes with several long tortuous teeth near apex; roots slender, ca. 0.5 mm in diam.. Frond approximate, 55–81 cm long. Stipe stramineous, 24–46(–53) cm, 1–2.5 mm in diam. at middle, narrowly grooved adaxially, base densely covered with same scales as on rhizome, upward scales becoming sparse and narrow, and with an enlarged base. Lamina ovate or ovate-oblong, 18–39 × 12–25 cm, imparipinnate to 2-pinnate, base round or rounded-cuneate, lower 2–4 pairs nearly equal in size, sometimes lowest pairs slightly longer and larger, usually with a conform terminal pinna, occasionally distal part abruptly narrowed to a caudate-acuminate apex, seldom gradually attenuate toward apex. (Lateral) pinnae 5–10 pairs, linear-lanceolate to narrowly lanceolate, sometimes falcate, alternate or lower 1–2 pairs opposite or subopposite, obliquely spreading, widely or closely spaced, lower 5 pairs nearly equidistant, (16–)20–40(– 50) mm apart, broadest at base or middle, shallowly pinnatifid to pinnate at lower part, stalked, stalk 3.5–7 mm on lower ones, base cuneate to broadly cuneate, symmetrical, sometimes asymmetrical, acroscopically broadly cuneate, basiscopically cuneate, apex acuminate to long acuminate; lowest pinnae 75–160 × 13–34 mm, basally pinnatisect to pinnate, lobes and pinnules (11–)18–28 pairs, obliquely spreading; free pinnules 1–5 pairs, anadromous, sessile to shortly stalked (stalk 0.5–1 mm), obovate, ovate, ovate-oblong or oblong, closely spaced, contiguous or imbricate, base cuneate to rounded-truncate, symmetrical or nearly symmetrical, acroscopic base of basal 1–2 pairs sometimes slightly auriculate, apex rounded, obtuse or subacute, basal pair of pinnules same as, or longer and larger than next pair, with acroscopic pinnule same as, longer or shorter than basiscopic one, acroscopic one 6.5–17 × 4–8 mm, basiscopic one 9–22 × 3.5–9 mm, margins serrate, aristate; lobes of middle part oblong, rectangular or triangular, apex with 1–8 aristate teeth; distal pinnae similar to basal pair, usually with a larger basal acroscopic pinnule (lobe). Terminal pinna (if with) same as or similar to lateral ones, 63–110 × 10–18 mm, linear-lanceolate to narrowly lanceolate, basally coarsely toothed to pinnatipartite, broadest at base or middle, base cuneate to broadly cuneate, stalked, stalk 4–11 mm, apex acuminate to long acuminate. Lamina texture papery when dry, adaxially brownish green, glossy, abaxially yellowish green, with 1 or 2 microscales along veins; rachis and costae stramineous, shallowly grooved adaxially, covered with sparse scales; scales nearly subulate, blackish brown or nearly black, enlarged at base, toothed on basal margin, apex hairlike; scales on lower part of rachis 4–6.5 × ca. 0.3 mm. Veins pinnate on lobes, single, fork or pinnate on pinnules, not reaching margin. Sori media, terminal or subterminal on acroscopic veinlets, in 1 row on each side of midrib of pinnule or in 2–4 irregular rows on each side of costa, not close to costa; indusium brown, membranous, orbicular-reniform, ciliate or lacerate at margin.

Geographical distribution:—The new species was only found in the type locality, Xichou County, Yunnan Province, Southwest China ( Fig. 3 ).

Ecology and Conservation Assessments: —One population was discovered at a slope of the margins of Chinese fir forest with over 30 individuals scattered at an area of approximately 100 m 2. Unfortunately, this area was mostly cleared and planted with many Lanxangia tsao-ko ( Crevost & Lemarié 1917: 300) M.F. Newman & Škorničková in De Boer et al. (2018: 24) . Obviously, most of the individuals of this population will be unable to survive beneath this commercial crop. However, the dry slope with plenty of natural light where the new species was found is very common. There are many similar habitats in the local area where probably some other populations exist. The new species is currently considered as critically endangered (CR) according to the IUCN guidelines ( IUCN 2012).

Etymology: —The epithet of the new species is derived from the Latin adjective “mira ,” meaning “strange, extraordinary”, referring to the strange and unstable frond shape of the new species.

Chinese name:—奇丽复叶fffi (qí lì fù yè ěr jué)

Figures

FIGURE 1. Arachniodes mira.—A. Habitat.—B. Habit.—C.Abaxial view of portion of lamina.—D.Adaxial view of portion of lamina.— E.Adaxial view of lamina.—F. D.Adaxial view of lamina.—G. Rhizome with lower portion of stipes.—H. Portion of rachis with pinna.— I. Scales from rachis (top and middle) and stipe base (bottom).

FIGURE 2. Arachniodes mira.—A. Habit.—B. Bipinnate frond.—C. Portions of pinnae showing venation, indusia and sori.—D. Scales of stipe base.

FIGURE 3. Geographical distribution of Arachniodes mira (center of rings) in Yunnan Province, China.