Selliguea quinquefida (Polypodiaceae), a new calciphilous species from a karst area in Guangxi, China Author Wei, Hong-Jin text Phytotaxa 2024 2024-05-21 649 3 279 285 http://dx.doi.org/10.11646/phytotaxa.649.3.5 journal article 10.11646/phytotaxa.649.3.5 1179-3163 Selliguea quinquefida H.J. Wei , sp. nov . ( Figs. 1 & 2 ). Type: — CHINA . Guangxi : Jingxi City , Huadong Town , Aibu Village , near the top of a limestone hill, 116°30'E , 23°0'N , elev. 710 m , 6 February 2018 , She-Lang Jin & Ping Yang JSL6220 ( holotype : CSH0199999 !; isotypes : CSH !, IBK !, KUN !, PE !) Diagnosis: — Selliguea quinquefida is similar to S. hastata but differs by the laminae of mature fronds often (vs. occasionally in the latter) pentagonal, and those of juvenile forms deltoid-ovate or hastate (vs. ovate to linear or lanceolate) and with cordate (vs. cuneate or rounded) bases. Description:—Plants terrestrial. Fronds 20–47 cm long, monomorphic, remotely spaced. Rhizome long creeping, with indeterminate growth, repeatedly branched, each ultimate branch often retaining only 1 frond annually, 1.5–3 mm in diam., densely clothed with scales; scales reddish brown at center, yellowish brown at margin, ca. 2.5–4.5 × 0.7–1.2 mm , ovate-lanceolate, broad and rounded at peltate base, with long filiform apex, membranous, lower margin irregularly toothed, upper margin with 1 or 2 cilia. Stipe stramineous at base, upward dark stramineous to chestnut-brown, 13–33 cm , 0.8–1.5 mm in diam. near middle, glabrous, phyllopodia 1–4(–6) mm, scales on phyllopodia subulate or ovate-lanceolate, 3–7 mm long. Lamina nearly cordate, deltoid-ovate, hastate or palmately 3- or 5-lobed, nearly cordate, deltoid-ovate or hastate ones 6–9 × 5–8.5 cm , palmate ones 7–16 × 9–16(–23) cm, base cordate, margins nearly entire or undulate, distinctly cartilaginous, remotely notched. Lobes deltoid to narrowly deltoid, central lobe usually longer than lateral ones, 6–10 × 2.5–3.5 cm , apex acuminate, outermost lobes usually shorter, apex obtuse or acute, sometimes acuminate, basiscopic base often auriculate. Lamina papery or sub-leathery when dry, yellowish green abaxially, grayish green adaxially, glabrous on both surfaces, hydathodes distinct, with calcareous secretions adaxially. Costa stramineous, distinct, notably raised abaxially, glabrous on both surfaces. Veins reticulate; lateral veins distinct, raised abaxially, not reaching margin; veinlets obscure, anastomosing, with simple or forked included veinlets in areoles. Sori orbicular, superficial, in one regular row on each side of costa, nearer to costa than to margin. Distribution and habitat: — Selliguea quinquefida is known only from the type locality ( Fig. 3 ), at ca. 710 m , growing under scattering low shrubs in relatively dry conditions near the top of a limestone hill, with rhizome creeping deeply within chalky soils derived from limestones ( Fig. 1D ). Conservation Assessments and Ecology: —Only one population was found on a limestone hill near a village situated at an unprotected region, with some individuals scattering at an area of about 80 square meters. The discoverer, Ping Yang has conducted many investigations in this karst region and adjacent areas since 2007 and never found another population. However, many limestone hills are difficult to climb and have always been omitted in plant investigations. It is suspected that there may be more populations in the region where the types were found or in karst regions of neighboring Vietnam . The new species is currently considered as Critically Endangered (CR) according to the IUCN guidelines ( IUCN 2022 ). FIGURE 1. Selliguea quinquefida .—A, B. Habitat.—C. Habit.—D. Fronds growing out from thick calcareous soil.—E. Scales from phyllopodium (up) and rhizome (down).—F. Rhizome.—G. Abaxial view of palmate lamina (left) and simple lamina (right). Etymology: —The epithet of Selliguea quinquefida is derived from the Latin “quinque,” meaning “five,” and the Latin “-fida”, cleft, referring to the lamina divided into five lobes. Chinese name:— 五ạ假瘤® (wú liè jiǎ liú jué) Additional specimens examined ( paratypes ): —The same place as the holotype , elev. 694 m , 31 May 2021 , Ping Yang & Xi-Tao Li ZYA00175 (IBK!).