Research Article |
Corresponding author: Zhao-Rong He ( zhrhe@ynu.edu.cn ) Corresponding author: Xin-Mao Zhou ( xinmao.zhou@ynu.edu.cn ) Academic editor: Angelo Troia
© 2023 Shao-Li Fang, Bo Xu, Liang Zhang, Zhao-Rong He, Xin-Mao Zhou.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Fang S-L, Xu B, Zhang L, He Z-R, Zhou X-M (2023) Selaginella densiciliata (subg. Heterostachys, Selaginellaceae), a new spikemoss species from China based on morphological and molecular data. PhytoKeys 227: 135-149. https://doi.org/10.3897/phytokeys.227.101222
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A new species of spikemoss, Selaginella densiciliata in S. subg. Heterostachys sect. Tetragonostachyae, China, is described from southeastern Xizang, based on morphological and molecular phylogenetic data. Morphologically, S. densiciliata is similar to S. repanda, S. subvaginata and S. vaginata, but the new species can be easily distinguished from them by having sterile leaves margins densely ciliate, symmetrical axillary leaves oblong ovate to ovate-triangular, and ovate dorsal leaves obviously carinate. Molecular phylogenetic analysis resolves S. densiciliata as sister to the clade comprised with S. vaginata and S. xipholepis, which confirms the recognition of the new species.
Medog, Selaginella vaginata, submonomorphic sporophylls, S. subg. Heterostachys
Located in southeastern Xizang, Medog county and adjacent regions are one of the biodiversity hotspots in the world (
The Selaginella vaginata group, including at least three species, i.e., S. subvaginata X.C.Zhang & Shalimov, S. repanda (Desv. & Poir.) Spring, and S. vaginata Spring, represents a taxonomically difficult group in S. sect. Tetragonostachyae of S. subg. Heterostachys sensu
Our previous phylogenetic study of Selaginella firstly found that the S. vaginata (= S. compta Hand.-Mazz. in
Our further studies of the morphology, phylogeny, and spore morphology of those species related to the S. vaginata group confirm that materials from Medog represent a new species. We describe it here as Selaginella densiciliata.
Field observations were conducted in June (in 2015) and October (in 2017) respectively. The photos of plants, leaves, and strobili were taken in the field. All research materials were deposited at KUN and PYU (Index Herbarium:
Total genomic DNA of seven samples (one from Selaginella dianzhongensis X.C.Zhang, two from S. wuyishanensis K.W.Xu, X.M.Zhou & Y.F.Duan, and four from the new species) was extracted from silica-dried material using the TIANGEN plant genomic DNA extraction kit (TIANGEN Biotech., Beijing, China) following the manufacturers’ protocols. One nuclear locus (ITS) and one plastid gene (rbcL) were selected for amplification and sequencing. Primers and the PCR conditions followed
Based on a previous phylogenetic study of Selaginella (
The aligned length of combined plastid gene (rbcL: 1277 bp) and nuclear loci (ITS: 425 bp) was 1702 bp, of which 1242 sites were identical, 389 characters were parsimony informative, and 71 variable characters were parsimony-uninformative.
As our previous phylogenetic studies for Selaginella (
Maximum likelihood phylogeny of Selaginella densiciliata and its allies in subg. Heterostachys. based on molecular data. The numbers associated with branches are maximum likelihood bootstrap support (MLBS) ≥ 50% and Bayesian posterior probability (BIPP) ≥ 0.50; the dash (--) indicates MLBS < 50% or BIPP < 0.50; the asterisk indicates MLBS = 100 or BIPP = 1.00; omitted support values indicate both MLBS < 50% and BIPP < 0.50. Sections followed
Comparison of morphological characters between Selaginella densiciliata and its morphologically similar species is shown in Table
Selaginella densiciliata A dorsal view of branches B ventral view of branches with strobili C ventral view of branches, showing rhizophores, axillary leaves, and ventral leaves D dorsal view of branches, showing dorsal leaves E ventral view of branches, showing axillary leaves, and ventral leaves F dorsal view of strobilus G ventral view of strobilus H axillary leaf on stems (left) and branches (right) I dorsal leaf J ventral leaf K dorsal sporophyll L ventral sporophyll M proximal surface of megaspore N distal surface of megaspore O proximal surface of microspore P distal surface of microspore (from the holotype: L. Zhang et al. 2215).
Morphological comparison among Selaginella densiciliata, S. repanda, S. subvaginata, and S. vaginata.
Selaginella densiciliata | S. repanda | S. subvaginata | S. vaginata | |
---|---|---|---|---|
Habit | Ascending to suberect | Suberect or ascending | Suberect | Creeping |
Leaves margin | Not white-margined | White-margined | Not white-margined | White-margined |
Axillary leave | Symmetrical, oblong-ovate to ovate-triangular | Symmetrical, ovate-lanceolate | Asymmetrical, ovate to ovate-triangular | Asymmetrical, ovate-triangular |
Dorsal leave | Ovate, margins ciliate, apex aristate; carinate | Obliquely ovate, margins denticulate; slightly carinate | Ovate-lanceolate, inner margins ciliate; slightly carinate | Ovate-lanceolate or ovate-triangular, base margins ciliate; slightly carinate |
Ventral leave | Oblong-falcate, basiscopic base margins denticulate | Ovate or obliquely ovate, basiscopic base margins ciliate | Oblong-falcate, basiscopic base margins denticulate | Ovate-lanceolate or ovate, basiscopic base margins denticulate |
Dorsal sporophyll | Ovate, margins denticulate | Ovate-lanceolate, margins denticulate | Ovate, base margins ciliate | Ovate-lanceolate, base margins ciliate |
Ventral sporophyll | Broadly ovate, margins denticulate | Broadly ovate, margins denticulate | Ovate, base margins ciliate | Ovate-lanceolate, margins denticulate |
Megaspore | Fine reticulate | Verrucate | Fine reticulate | Verrucate |
Microspore | Verructae and rugulate with spiny microstructure | Verructae and rugulate | Smooth | Verructae and rugulate |
Submonomorphic sporophylls are similar dorsal and ventral sporophylls in morphology, but dorsal sporophylls are slightly larger than ventral ones. Submonomorphic sporophylls are only present in some species of S. sect. Heterostachys (e.g., S. monospora Spring) and S. sect. Tetragonostachyae (Hook. & Grev.) Hieron. & Sadeb. in S. subg. Heterostachys sensu
China. Xizang: Medog County, Beibeng Township, on the way from A’niqiao to #3 bridge, in broad-leaved evergreen forest, 29°20'41.56"N, 95°9'56.99"E, elev. 1600 m, 15 Oct. 2017, Liang Zhang, Wen-Bin Ju & Heng-Ning Deng2215 (holotype: KUN-1572683!, isotypes: KUN-1572684!, PYU-02074721!, PYU-02074722!).
Selaginella densiciliata is similar to S. repanda, S. subvaginata, and S. vaginata in having relatively small plants (Fig.
Plants
terrestrial, evergreen, ascending to suberect, 7.0–15.0 cm tall, without creeping rhizomes or stolons, without elongate tuber at base of stem (Fig.
Selaginella densiciliata is only known from Beibeng Township, Medog County, Xizang Province, China. It grows in humid places in evergreen broadleaved forests, at elevations of 1000–1600 m.
China. Xizang: Nyingchi City, Medog county, Beibeng township. on the way from A’niqiao to Hanmi village, elev. ca. 1000 m, 29°20'14.40"N, 95°10'19.19"E, 4 Jun. 2015. Bo Xu & Xin-Mao Zhou YLZB2043 (CDBI, PYU); on the way from A’niqiao to Hanmi village, elev. 1530 m, 29°20'29.51"N, 95°10'12.74"E, 15 Oct. 2017, Liang Zhang, Wen-Bin Ju & Heng-Ning Deng 2090 (KUN, PYU); on the way from A’niqiao to Hanmi village, alt. 1120 m, 29°19'42.75"N, 95°10'36.47"E, 17 Oct. 2017, Liang Zhang, Wen-Bin Ju & Heng-Ning Deng 2203 (KUN, PYU).
The specific epithet “densiciliata” is a compound word derived from the Latin word “dense” which means dense and suffix “ciliata” which means ciliate. The specific epithet “densiciliata” refers to sterile leave (axillary leaves, dorsal leaves, and ventral leaves, Fig.
1 | Stem nearly creeping, only fertile parts (strobili) ascending | S. vaginata |
– | Stem more or less suberect or ascending | 2 |
2 | Leaves distinctly white-margined | S. repanda |
– | Leaves not obviously white-margined | 3 |
3 | Base of sterile leave margins sparsely ciliate or denticulate; axillary leaves asymmetrical; dorsal leaves ovate-lanceolate, slightly carinate; microspore surface smooth | S. subvaginata |
– | Base of sterile leave margins densely ciliate; axillary leaves symmetrical; dorsal leaves ovate, obvious carinate; microspore surface verrucate | S. densiciliata |
The research was supported by the National Natural Science Foundation of China (NSFC) to X.M. Zhou (#31900186, #32260050). We thank the two anonymous reviewers for their valuable comments and suggestions.
No conflict of interest was declared.
No ethical statement was reported.
No funding was reported.
Conceptualization: BX. Formal analysis: SLF. Funding acquisition: XMZ. Methodology: SLF. Project administration: XMZ. Resources: BX. Software: SLF. Supervision: XMZ. Writing - original draft: XMZ, SLF. Writing - review and editing: ZRH, BX, LZ.
All of the data that support the findings of this study are available in the main text or Supplementary Information.
List of taxa sampled with information related to taxonomy, GenBank accession numbers (rbcL, ITS), references, and vouchers information. Herbarium codes follow Index Herbariorum (
S. albociliata P. S. Wang (1) L.-B. Zhang et al.et al. 5302 (CDBI), China (Guangxi), KT161379 (