Dryopteris shiakeana H. Shang &Y. H. Yan, 2015

Shang, Hui, Ma, Qi-Xia & Yan, Yue-Hong, 2015, Dryopteris shiakeana (Dryopteridaceae): A new fern from Danxiashan in Guangdong, China, Phytotaxa 218 (2), pp. 156-162 : 158-161

Dryopteris shiakeana H. Shang &Y. H. Yan , sp. nov. Figs. 1, 2 .

Type:— China. Danxiashan National Park , Guangdong. 25° 01 ′ 14 ′′ N, 113° 40 ′ 25 ′′ E, 5 May 2012, YYH1205119 (holotype, CSH!; isotypes, CSH!) .

Dryopteris shiakeana is most similar to D. dehuaensis in general morphology; both species contain exindusiate sori, basiscopic pinnule stalks exceeding 1 cm, and downside swallow-tailed, elongate basal pinnae. However, the former differs from the latter because by having dense scales on the rachis of laminae and pinnae, dissected pinnules, more prominent veinlets, reddish brown scales on stipes, and toothed segment margins.

Terrestrial, evergreen, 40–60 cm tall. Rhizome, recumbent or erect, apex densely covered with linear-lanceolate and lustrous reddish-brown scales. Cespitose, 3–5 fronds per plant. Stipes, sepia and reddish-brown at base, 20–30 cm, ca. 4 mm in diameter at the base and densely covered with lanceolate, reddish-brown scales at the base; upward scales becoming small, appressed. Lamina, ovate-lanceolate, approximately 20–30 cm long, 20–30 cm wide at the base, tripinnate, pinnatifid, and acuminate at the apex, lowest basiscopic pinnule on the lowest pinna distinctly enlarged, directed downward. Pinnae, 8–12 pairs, alternate, lanceolate, stalked; largest basal pinnae, 15 cm, with stalks 1–2 cm; basiscopic pinnules usually larger than acroscopic ones; lowest basiscopic pinnule on lowest pinna largest. Pinnules, 15–18 pairs, oblong, round-cuneate base forms, apices blunt or subacute, base pinnules pinnatisect; pinnules on upper part from pinnatisect to pinnatilobate; segments closely linked, divided only by a narrow slit, nearly oblong, truncate at the apex, with teeth at the margin. Veins, visible at both sides, prominent abaxially; veinlets, 3–4 pairs each segment, 1- or 2-pinnate, branching, reaching the margin. Lamina, papery, yellowish-green; rachis and pinna rachis densely covered with reddish-brown appressed scales, pinnule rachis and costa covered with brown, bullate scales abaxially. Sori, small and medial, between the midrib and the margin of pinnule, exindusiate.

Etymology: —The epithet is from the name of a famous Chinese geographer Xiake Xu, who first described

Danxia landform in southern China in the book Travels of Xu Xiake, which was published in 1642. Habitats: —Terrestrial, subtropical evergreen broadleaved forest in Danxiashan National Park. Additional specimens examined (paratypes): —The same site of holotype, YYH13163-1, YYH13163-2,

YYH13163-3, YYH13163-4, YYH13163-5, YYH13163-6, YYH13163-7, YYH13163-8, YYH13163-9, YYH13163-

10, YYH13163-11, YYH13163-12, YYH13163-13, YYH13163-14, and YYH13163-15.

IUCN Conservation assessment: —EN(B1ab(iii)). No other individuals were found in other locations. Only ca. 20 individuals were collected in the type locality. Based on restricted geographic range, small populations, and less number of individuals, D. shiakeana should be considered endangered in accordance with the IUCN Red List criteria ( IUCN 2014).

Figures

FIGURE 2. Morphological comparison between D. dehuaensis (1A–1E) and D. shiakeana (2A–2E). A, B. Lamina. C, D. Pinnules and costa. E. Basal petiole and scales.