Selaginella daozhenensis Li Bing Zhang, Q.W. Sun & Jun H. Zhao, 2015

Sun, Qing-Wen, Zhao, Jun-Hua & Zhang, Li-Bing, 2015, Selaginella daozhenensis (Selaginellaceae), a new lycophyte from a limestone cave in northern Guizhou, China, Phytotaxa 207 (2), pp. 187-192 : 187-191

publication ID	https://doi.org/ 10.11646/phytotaxa.207.2.5
persistent identifier	https://treatment.plazi.org/id/03C487F3-FFC9-1749-16C5-84BDFB178326
treatment provided by	Felipe
scientific name	Selaginella daozhenensis Li Bing Zhang, Q.W. Sun & Jun H. Zhao
status	sp. nov.

Treatment

Selaginella daozhenensis Li Bing Zhang, Q.W. Sun & Jun H. Zhao View in CoL , sp. nov. ( Figs. 1 View FIGURE 1 & 2 View FIGURE 2 ).

Selaginella daozhenensis View in CoL is similar to S. labordei Hieronymus ex Christ (1902: 272) View in CoL and S. sichuanica H.S. Kung (1981: 252) View in CoL , but the new species is distinct by its leaves being bluish green when fresh, its median leaves having aristae as long as leaves, and its lateral leaves being larger (3.5–5 × 1.7–2.5 mm).

Type:— CHINA. Guizhou Province: Daozhen County, Dashahe Nature Reserve, 29°07.39’N, 107°35.35’E, 1280 m, inside a limestone cave with north-facing mouth, 16 Aug. 2014, Qing-Wen Sun, Jun-Hua Zhao & Lu-Tai Pan 201435 (holotype GZTM!, isotypes CDBI!, PYU!).

Plants terrestrial, summer-green, (8–)13–16(–20) cm tall, with creeping subterranean rhizome and stolons. Rhizophores restricted to base of stem or borne on creeping rhizomes and stolons. Main stems erect, 2–4 times pinnately branched, glabrous, castaneous or stramineous, 0.6–1.0 mm diam. in basal portion, terete, slightly sulcate, with 1 vascular bundle; branches 8–12, 0.6–1.7 cm apart from each other, middle branches longer than the other, ultimate branches 4–5 mm wide including leaves. Leaves trimorphic, bluish green when fresh, whitish and short-ciliate on rhizomes, sparse on unbranched main stem and base of branches, dense on branchlets: axillary leaves on middle main stem narrowly ovate, 3–4 × 1.5–2 mm, rounded or slightly cordate at base, acute at apex, margins sparsely ciliate; axillary leaves on upper main stem and lateral branches ovate-lanceolate, 2.5–3 × 0.8–1.2 mm, rounded or slightly cordate at base, acute to acuminate at apex, margins sparsely ciliate ( Figs. 1D View FIGURE 1 , 2L View FIGURE 2 ); median leaves on middle main stem ovate, 1.8–2.1 × 0.6– 0.7 mm, asymmetrical at base, apex with arista as long as leaves, margins ciliate; median leaves on upper main stem and lateral branches ovate, 2.7–3.0 × 1.3–1.5 mm, cordate and symmetrical at base, apex with arista as long as leaves, margins ciliate ( Figs. 1B, C View FIGURE 1 , 2J, K View FIGURE 2 ); lateral leaves ovate-lanceolate to lanceolate, 3.5–5.0 × 1.7–2.5 mm, asymmetrical at base, acute at apex, margins ciliate ( Figs. 1A View FIGURE 1 , 2H, I View FIGURE 2 ). Strobili compact, dorsiventrally complanate, solitary, on terminal or lateral branches, (3–)5–8(–11) × 3–4 mm ( Fig. 2D, E View FIGURE 2 ). Sporophylls obviously dimorphic: median sporophylls ovate, 1.9–2.1 × 0.7–0.8 mm, keeled, base rounded, apex long-aristate, margins ciliate; lateral sporophylls ovate-lanceolate, 2.4–2.6 × 1.1–1.3 mm, keeled, apex acuminate ( Figs. 1E, F View FIGURE 1 , 2F, G View FIGURE 2 ). Microsporangia borne on lower to middle portions of strobili; microspores orange (immature). Megasporangia not seen.

Etymology: —The epithet of the new species is taken from the Chinese pinyin, daozhen, the name of the county in northern Guizhou, China where the type was collected from.

Distribution and Habitat:— Known only from the type collection growing on limestone soil in a cave of the Dashahe Nature Reserve at ca. 1280 m, Selaginella daozhenensis may prove to be an endemic of this type of habitat as has been shown for species of the fern genus Polystichum that grow under similar conditions as reported by Zhang & He (2010, 2011, 2012). The soil at the type location was of basic pH.

IUCN Red List category:— Only about five populations inside a cave in Daozhen County with several hundred individuals were found. The habitat of Selaginella daozhenensis in Daozhen County is inside the Dashahe Nature Reserve, but there was no protection measure taken to conserve the habitat. Based on the evidence available, S. daozhenensis should be classified as Critically Endangered or CR, following The International Union for Conservation of Nature and Natural Resources guidelines ( IUCN, 2012).

Discussion:— Morphologically, Selaginella daozhenensis is most similar to S. sichuanica in its long-aristate apex of median leaves, but the former is (8–)13–16(–20) cm tall, the margins of its median leaves have cilia, and the apex of median leaves has aristae as long as leaves, while the latter is only 5–11 cm tall, the margins of its leaves have only serrulations, and the apex of median leaves has aristae obviously shorter than the rest of the leaves. Also, the former is found only at median elevations (1280 m) while the latter occurs at high elevations between 2000–2500 m ( Kung 1981, 1988).

Selaginella daozhenensis is also similar to S. labordei , but the former has long-aristate apices of median leaves, larger (3.5–5 × 1.7–2.5 mm) lateral leaves, and only cilia at the margins of its median leaves, while the latter has acute apex of median leaves, smaller (2–3 × 1–1.8 mm) lateral leaves, and serrulations at the margins of its median leaves. In addition, S. daozhenensis has leaves bluish green when fresh, while both S. labordei and S. sichuanica have leaves green when fresh.

Selaginella daozhenensis is the second cave species of Selaginella discovered in Guizhou after S. wangpeishanii Li Bing Zhang, H. He & Q.W. Sun (2014: 195) from southern Guizhou. There might be more cave species of Selaginella awaiting to be discovered given the rich cave resources in Guizhou and adjacent Guangxi and Yunnan provinces.

Notably, Zhang (2004) and Zhang et al. (2013) thought that Selaginella sichuanica was an ecological form of S. labordei and treated the former as a synonym of the latter. However, these two species are different in morphology, ecology and geographical distribution. Selaginella sichuanica has a much smaller habit, monomorphic sporophylls, and long aristae at apex of median leaves, and occurs at higher elevations in a narrow geographical area ( Kung 1981, 1988). Our molecular analysis shows that S. daozhenensis , S. labordei , and S. sichuanica are all distinct species (Zhou et al. unpubl. data).

These three morphologically related species are compared with one another in Table 1.