Sphaeropteris guangxiensis Y. F. Gu & Y. H. Yan (Cyatheaceae), a new species of tree fern from Southern China Author Gu, Yu-Feng 0000-0002-4089-3937 Life Science and Technology College, Harbin Normal University, Key Laboratory of Plant Biology in Colleges of Heilongjiang Province, Harbin 150025, Heilongjiang, China & Shanghai Chenshan Botanical Garden, Shanghai Chenshan Plant Science Research Center, Shanghai 201602, China & Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, the National Orchid Conservation Center of China and the Orchid Conservation & Research Center of Shenzhen, Shenzhen 518114, Guangdong, China & shguyufeng @ 163. com; https: // orcid. org / 0000 - 0002 - 4089 - 3937 & 13224512780 @ 163. com; https: // orcid. org / 0000 - 0002 - 6178 - 3622 Author Jiang, Ri-Hong 0000-0003-4908-3487 Guangxi Forestry Research Institute, Guangxi Key Laboratory of Special Non-wood Forest Cultivation & Utilization, Guangxi Engineering and Technology Research Center for Woody Spices, Nanning 530002, Guangxi, China & jiangrhg @ 163. com; https: // orcid. org / 0000 - 0003 - 4908 - 3487 Author Liu, Bao-Dong 0000-0002-0793-8240 Life Science and Technology College, Harbin Normal University, Key Laboratory of Plant Biology in Colleges of Heilongjiang Province, Harbin 150025, Heilongjiang, China & 99 bd @ 163. com; https: // orcid. org / 0000 - 0002 - 0793 - 8240 Author Yan, Yue-Hong 0000-0003-3911-4868 Shanghai Chenshan Botanical Garden, Shanghai Chenshan Plant Science Research Center, Shanghai 201602, China & Key Laboratory of National Forestry and Grassland Administration for Orchid Conservation and Utilization, the National Orchid Conservation Center of China and the Orchid Conservation & Research Center of Shenzhen, Shenzhen 518114, Guangdong, China & yan. yh @ 126. com; https: // orcid. org / 0000 - 0003 - 3911 - 4868 text Phytotaxa 2021 2021-08-31 518 1 69 74 journal article 4367 10.11646/phytotaxa.518.1.8 08ffd262-ba20-4df7-a7ea-b0e9dc80eedb 1179-3163 5448015 Sphaeropteris guangxiensis Y.F. Gu & Y.H. Yan ( Figure 1 ) Type:— China . Guangxi Province : Fangchenggang City , Dongxing County , Taohuaxi Village , 21°38′7″N , 107°41′22″E , 256 m , 01 May 2018 . Morigengaowa & Jun-Jie Luo CFH09001402 ( holotype , CSH ! ( CSH0155370 ); isotypes, PE !; paratypes , Morigengaowa & Jun-Jie Luo CFH09001403, Morigengaowa & Jun-Jie Luo CFH09001404, CFH09001405, and CFH09001406 , CSH !) Diagnosis:— Sphaeropteris guangxiensis is most similar to S. brunonina and S. hainanensis in terms of morphological characters of leaf, but the difference is that fiddleheads (young leaves spirally coiled in bud) of S. guangxiensis are densely scaly on the adaxial surface and few on the abaxial surface, fiddleheads of S. brunonina are fully scaly on both sides, and fiddleheads of S. hainanensis are not scaly ( Figure 3 A ~C). FIGURE 1. Sphaeropteris guangxiensis Y.F. Gu & Y.H. Yan. — A. One pinna. — B. Pinnule segments. — C. Spores. FIGURE 2. Sphaeropteris guanxiensis .—A & B. Habit.—C. Petioles and scales on the trunk.—D & E. Petiole crosscutting and the annular vascular bundles (photographed by Jun-Jie Luo).—F, G & H. Spore morphology. Description:— Trunk erect, approximately 10 m tall, up to 20 cm in diameter. Stipes warty at base, upper part and rachis smooth, yellowish to purplish. Lamina 2-pinnate-pinnatifid, up to 3 × 1.6 m , pinnae 20–30 pairs, ascending, lanceolate; largest pinnae up to 90 × 25 cm . Pinnules narrowly lanceolate, 9–14 × 1.8–2.5 cm , slightly narrowed at base, apex caudate, pinnatifid to pinnatisect; pinnule segments 13–22 pairs, falcate, wider at base, entirely or minutely crenate; veins 2- or 3-forked; abaxial side of pinnules glabrous, adaxial side glabrous or with sparse hairs; lamina glaucous abaxially; adaxial side of pinna rachis smooth or with pale antrorse hairs. Fiddleheads with thick scales at middle and brown hairs outside. Sori close to midveins of fertile pinnule segments, 5–8 pairs per segment, covering 3/4–5/6 segment; paraphyses pale to brown, filamentous, longer than or equal in length to sporangia; indusia absent. Spore granulate, thick, ca. 35- 45 μm in diam., polar view triangle, straight edge, equatorial view sector. Distribution:— Sphaeropteris guangxiensis grows at the edges of forests. Present the new species is known only from the type locality. FIGURE 3. Fiddleheads and sori on pinnule segments. —A & D. Sphaeropteris brunoniana . —B & E. S. guangxiensis . — C & F. S. hainanensis . Ecology:— The species was found associated with some woody plants ( Figure 2 : A, B), such as Mallotus japonicus ( Sprengel 1826: 878 ) Müller Argoviensis (1865: 189) , Mangifera indica Linnaeus (1753: 200) , and Bambusa chungii McClure (1936: 639) . It was also found to be associated with species of Arecaceae Bercht. & J. Presl , ferns such as Asplenium nidus Linnaeus (1753: 1079) , Lemmaphyllum rostratum ( Beddome 1866: 159 ) Tagawa (1966: 193) , and Microsorum punctatum ( Linnaeus 1763: 1524 ) Copeland (1929: 111) were found to be associated with their trunk. Approximately 50 adult plants and a few young ones were found in the population. IUCN Red List category:— Sphaeropteris guangxiensis has a restricted geographic distribution, and yet not found in other regions out of the type locality. Local people occasionally utilize this species as firewood. Our field investigations showed that there were no abnormalities in the spores of the new species which indicated that the new species can replenish themselves. Moreover , we observed hundreds individuals of this species in a large population at the border of Guangxi Province , China and Vietnam . The status of the new species can be classified as Endangered ( EN ) [ A2 a; B2 b(iv)(v)], but more investigations are still needed to accurately assess its conservation status .