Selaginella chuweimingii Xin M. Zhou, Z. R. He, Liang Zhang & Li Bing Zhang 2015, sp. nov.
Creators: name: Zhou, Xin-Mao
name: He, Zhao-Rong
name: Zhang, Liang
name: Zhang, Li-Bing
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Lycopodiopsida
Selaginellales
Selaginellaceae
Selaginella
Selaginella chuweimingii

description: Selaginella chuweimingii Xin M. Zhou, Z. R. He, Liang Zhang & Li Bing Zhang, sp. nov. (Figs. 1, 2)   
 Type:— CHINA. Yunnan: Yuxi City, Yimen County, Lüzhi Town, 101°57'42.7464" E. 24°40'2.2404" N, alt. 1250 m, 16 October 2014, Xin-Mao Zhou & Li-Jü Jiang 216 (holotype CDBI!, isotypes MO!, PYU!).   
 Selaginella chuweimingii is most similar to S. sinensis (Desvaux 1827: 189) Spring (1843: 137) in the habit and the morphology of strobili and sporophylls, but the former can be distinguished from the latter by having ovate or oblong-ovate ventral leaves and extremely asymmetrical dorsal leaves, and oblong-ovate to ovate-lanceolate axillary leaves.   
 Plants terrestrial, xerophytic, seasonally green, main stem creeping, branches ascending, 25–70 cm (probably even longer), without creeping rhizomes or stolons. Rhizophores at intervals throughout length of main stem and branches, borne on ventral side in axils of primary branches, 5–13 cm long, slender, 0.1–0.2 mm diam.; roots much forked at end, 2.0– 5.5 cm long, hairy. Main stems branched throughout, inarticulate, pinnately branched or forked occasionally, stramineous or reddish (when alive), 0.4–1.0 mm diam., terete, glabrous, with a single vascular bundle, apex of main stem not blackish, stramineous; some of the primary lateral branches developing into long branch systems, 4–12 cm long; primary leaf branches 14–25 pairs, 1–4 times pinnately branched, ultimate branches forked or simple, branchlets sparse and regular, adjacent primary branches on main stem 1.9–2.5 cm apart, leafy branches glabrous, main stem of the leafy portion including leaves 3.5–5.5 mm wide in the middle, ultimate branches 3.0– 4.5 mm wide including leaves. Ventral leaves slightly symmetrical, those on main stem not obviously larger than those on branches; ventral leaves on main stem distant, on branches spreading or imbricate, ovate or oblong-ovate, 1.5–2.5 × 0.5–1.2 mm, white-margined, apex obtuse or slightly acute; acroscopic base strongly enlarged, auriculate, entirely overlapping stem and branches usually, margins densely ciliolate (0.3–1.0 mm), at acroscopic 1/2, less or obviously denticulate upward; basiscopic base slightly auriculate, margin ciliolate at base, less obviously denticulate upward; midrib slightly obvious on ventral side. Axillary leaves symmetrical, those on main stem not obviously larger than those on branches; oblong-ovate to ovate-lanceolate, 0.8–1.5× 0.2–0.5 mm, white-margined, base rounded to slightly cordate, apex acuminate, margin ciliolate (0.3–1.2 mm) at basal 1/2–2/3, sparsely denticulate upward; vein slightly obvious on ventral side. Dorsal leaves nearly symmetrical to strongly asymmetrical, those on main stems not obviously larger than those on branches; ovate-lanceolate to obliquely ovate, 1.2–2.0 × 0.3–0.8 mm, not carinate, margin ciliolate or denticulate, base obliquely subcordate; apex acuminate to aristate, parallel to axis or apical arista curved outside; midrib slightly obvious on dorsal side. Strobili solitary or occasionally in pairs, terminal, compact, tetragonal, 3.0–9.5× 1.3–2.2 mm; sporophylls monomorphic, obviously white-margined, ovate or broadly ovate, carinate, margins densely and regularly shortly ciliolate, apex acuminate; with only one megasporophyll at base of lower side, elsewhere with microsporophylls. Megaspores white, globose, equatorial axis 577.0–582.9 μm; laesurae slightly sinuous and extend 3/4 of distance to equator; both distal and proximal surfaces with irregularly sized and spaced lamellate ornamentation. Microspores yellowish orange, hemispherical, equatorial axis 25.9–27.0 μm; sinuous laesurae extend to equator, with verrucae; proximal surfaces verrucate, distal surfaces with less prominent verrucae and ridges.   
 Paratypes: — CHINA. Yunnan: Yimen County, 1300 m, 20 October 1965, W. M. Chu 1313 (PE, PYU), 1240 m, 26 March 1983, W. M. Chu et al. 15856 (PYU), 1250 m, 1 July 2003, X. C. Zhang s. n. (PYU-01001230); Luquan County, 1150 m, 06 May 1964, W. M. Chu 1634 (PE, PYU), 1150 m, 22 May 1965, W. M. Chu 640 (PYU).   
 Distribution and habitat: — Selaginella chuweimingii was only found in Yimen and Luquan County, central Yunnan Province, southwest China. It may be also distributed in the adjacent counties, such as Shuangbai, Lufeng, Anning, and Wuding. Plants of this species grow on rocky slopes, in crevices in the rock or in grass in dry and warm valleys at elevations of 1150–1300 m.   
 IUCN Red List category: —Only one population of Selaginella chuweimingii was observed at the type location. Although we speculate that S. chuweimingii is more widely distributed, its occurrence in two small localities in two adjacent counties in central Yunnan could be confirmed only on the basis of specimen examination. Based on the information currently available and following the IUCN Red List Criteria (IUCN Standards and Petitions Subcommittee, 2014), this species should be classified as Critically Endangered (CR).   
 Etymology: — Selaginella chuweimingii is named in honor of Professor Wei-Ming Chu of the Herbarium PYU, Yunnan University, Kunming. He devotes his whole life to studying the taxonomy of the lycophytes and ferns of China.   
 Discussion: —Morphologically, Selaginella chuweimingii is close to S. sinensis in having ciliolate leaves with white margins, and strobili only with one megasporophyll at base of the lower side. They also share creeping habit (Fig. 2A, B) and a preference for dry habitats. However, S. chuweimingii has ovate or oblong-ovate ventral leaves (Fig. 2C–E) (vs. obovate in S. sinensis), oblong-ovate to ovate-lanceolate axillary leaves (Fig. 2D) (vs. usually obovate in S. sinensis) and extremely asymmetrical dorsal leaves (Fig. 2C) (vs. somewhat symmetrical dorsal leaves in S. sinensis) (also see Table 1). Also, megaspore surfaces of S. chuweimingii have lamellate ornamentation (Fig. 2F, G) and distal surfaces of microspores are covered with less prominent verrucae and ridges (Fig. 2I), in contrast, the megaspores surfaces of S. sinensis are covered with prominent verrucae (Fig. 2J, K), and distal surfaces of microspores have prominent and wide ridges (Fig.2M). Geographically, S. chuweimingii is probably endemic to central Yunnan, southwest China, while S. sinensis is mainly distributed in the northern and eastern China, i.e., Anhui, Hebei, Heilongjiang, Henan, Jiangsu, Jilin, Liaoning, Nei Mongol, Ningxia, Shaanxi, Shandong, and Shanxi (Zhang et al. 2013).   
 As an important morphological character, sporangial arrangement of Selaginella has much been studied (Horner & Arnott 1963, Quansah 1988, Zhao et al. 2001). The strobili of S. chuweimingii and S. sinensis have only one megasporophyll at the base of the lower side, and elsewhere are microsporophylls. This strobilus type is shared by the species of the articulate group which usually grow at wet habitats and have dorsal rhizophores and articulate stems (Mickel & Smith 2004). Two species of this group, S. remotifolia Spring (1854: 276) and S. kraussiana (Kunze 1844: 114) Braun (1860: 22), occur in China (Zhang et al. 2013). Interestingly, S. chuweimingii and S. sinensis are xerophytic and have inarticulate stems and ventral rhizophores. Previous phylogenetic studies supported that articulate species are potentially a monophyletic group, while the phylogenetic position of S. chuweimingii (Zhou et al. 2015b) and S. sinensis (Korall & Kenrick 2002, 2004, Zhou et al. 2015b) is still uncertain. To reveal the phylogenetic relationship of all these species mentioned above, more molecular studies are needed.
description: Published as part of Zhou, Xin-Mao, He, Zhao-Rong, Zhang, Liang & Zhang, Li-Bing, 2015, Selaginella chuweimingii (Selaginellaceae) sp. nov. from Yunnan, China, pp. 283-288 in Phytotaxa 231 (3) on pages 284-287, DOI: 10.11646/phytotaxa.231.3.6, http://zenodo.org/record/13632061