Research Article |
Corresponding author: Xian-Chun Zhang ( zhangxc@ibcas.ac.cn ) Academic editor: Angelo Troia
© 2019 Aleksandr Petrovich Shalimov, Yan-Mei Zhu, Meng-Hua Zhang, Xian-Chun Zhang.
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:
Shalimov AP, Zhu Y-M, Zhang M-H, Zhang X-C (2019) Selaginella dianzhongensis (Selaginellaceae), a new spikemoss from China. PhytoKeys 118: 75-87. https://doi.org/10.3897/phytokeys.118.30375
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A new species of spikemoss from Yunnan Province of China, Selaginella dianzhongensis, is described and illustrated based on evidence from gross morphology, micromorphology and molecular phylogeny. S. dianzhongensis is most similar to S. amblyphylla in its habit of creeping stem, leaf size, and obviously dimorphic sporophylls, but is distinct by its ventral leaves ovate-oblong, subcordate at base, basiscopic base entire, axillary leaves ovate and decurrent at base. Molecular phylogeny analysis of three chloroplast gene regions (rbcL, atpI, psbA) shows that S. dianzhongensis forms an independent branch with strong support which is distantly related to S. amblyphlla and S. kurzii, but sister to S. bodinieri which is quite different in habitat of erect or ascending stem and rhizophores restricted to the lower part, and slightly dimorphic sporophyllus.
Lycophytes, Selaginella amblyphylla , taxonomy, Yunnan, rbcL, atpI, psbA
The initial critical taxonomic revision of Chinese Selaginella was published by
During field trips in Yunnan, we collected an unknown Selaginella species from Yimen County in central Yunnan. Morphology characters show it is similar to S. amblyphylla Alston, but phylogenetic analysis based on three chloroplast gene regions show it is close to S. bodinieri Hieron. Both molecular and morphology data support the taxon as a new species, which is described and illustrated here.
The new species belongs to subgenus Heterostachys in the classification system of
Herbarium specimens, silica gel and living materials were collected from Longquan Forest Park of Yimen (Yunnan province), in evergreen forest at 24°40'86"N, 102°08'27.86"E. Herbarium specimens are preserved in PE, and compared with similar species. The morpho-photographs of the plants were taken with a Nikon DXM 1200F camera connected to a stereomicroscope (Nikon SMZ 1000) and computer, measurements were done by D 3.10 (http:// www.nikoninstruments.com). The application ImageJ (https://imagej.nih.gov/ij/) was used to measure morphological characteristics (such as axillary, dorsal, ventral leaves, stems and strobili).
For study of spore morphology, scanning electron microscopy (SEM) was used. The spores were taken from mature sporangia and fixed on double line tape, and then covered with gold-palladium mixture. Spores were photographed and measured under different magnifications using a Hitachi S-4800 at 10–20 kV.
In this study, we sampled 28 taxa, representing almost all Chinese species with dimorphic strobili. Total genomic DNA was isolated from silica-dried material using the Plant Genomic DNA Kit (Tiangen Biotech, Beijing, China) following the manufacturer’s protocols. For each species, we attempted to amplify three chloroplast gene regions (rbcL, atpI, psbA) for the possible new taxa and its putative closely related taxa. These three regions were amplified with newly designed primers rbcL 192F (5’CACGTGGACTACCGTTTGGA3’) and 1324R (TACCCTCAAGAGCGGGATCA3’), atpI 119F (5’CYCAGGTTCATGGACAAGTAC3’) and atpI 540R (5’GRGTATYGGGGTTGGTTG3’), psbA 169F (5’CACGTGGACTACCGTTTGGA3’) and psbA 1026R (5’ATCTRGWGGGAAGTTGTGAGC3’), respectively. According to recent classification of Selaginella (
Phylogenetic tree of combined dataset (rbcL+atpI+psbA) was constructed using maximum likelihood (ML) and Bayesian inferences (BI). jModelTest 0.1.1 (
The new species resembles Selaginella amblyphylla in habit and gross morphology, but it is different in stems and branches reddish (vs. stramineous in S. amblyphylla), ventral leaves ovate-oblong, 1.1–2.2 × 0.4–0.8 mm (vs. oblong, 2–3 × 0.6–1.2 mm), base subcordate, basiscopic margin not ciliolate (vs. rounded and margin sparsely ciliolate); dorsal leaves oblique subcordate or cordate at base (vs. obliquely cordate), margin with rather long cilia (vs. denticulate or ciliolate); axillary leaves ovate and decurrent at base (vs. ovate or triangular and obtuse to decurrent at base); strobili 3.2–4.0 × 2.3–3.5 mm (vs. 3.5–10 × 3.2–4.4 mm), ventral sporophylls margin ciliolate, dorsal sporophylls margin denticulate (vs. both sporophylls margin ciliolate).
Selaginella dianzhongensis X.C.Zhang, sp. nov. A individual B portion of plant C habit D dorsal leaf E ventral leaf F strobili G axillary leaf H proximal surface of megaspore I distal surface of megaspores J portion of megaspore surface enlarged to show infrastructural detail K distal surface of microspore L proximal surface of microspore M portion of microspore surface enlarged to show infrastructural detail surface (Taken from Yan-Mei Zhu 8158 (PE)).
CHINA, Yunnan Province, Yimen County, Longquan Forest Park, 9 Feb 2017, Yan-Mei Zhu 8158 (Holotype, PE!; isotype PE).
Plants terrestrial, evergreen. Main stems reddish, creeping or suberect, stems 15–25 cm long, 0.6–1.0 mm in diam., branches stramineous. Rhizophores restricted in basal part of main stems or at intervals throughout length of creeping stem and branches, borne on ventral side in axils of branches. Main stems branched from near base, slightly sulcate, primary branches 0.7–1.5 cm apart, secondary branches once or twice pinnately branched, leafy portion of main stem including leaves 6–8 mm wide at middle, ultimate branches 4–7 mm wide including leaves. Axillary leaves on main stems and branches symmetrical, ovate, 1.1–2.2 × 0.4–0.8 mm, at base decurrent, margin sparsely long ciliate at base, ciliolate or denticulate to the apex, apex acute. Dorsal leaves ± symmetrical, on main stems distantly, on branch imbricate, on main stem larger than on branches, ovate to broadly ovate, 1.2–1.9 × 0.5–1.0 mm, slightly carinate on abaxial surface, in base oblique subcordate or cordate, not peltate, margin ciliolate at base, apex long aristate, arista 0.3–0.6 mm long. Ventral leaves asymmetrical, slightly distant, on main stem bit larger than those on branches, ovate-oblong, 1.7–3.9 × 0.7–1.6 mm, in base subcordate; acroscopic base slightly overlapping stems and branch, margin long ciliolateat base, denticulate to the apex, basiscopic bases free from stems, margin entire, apex acute. Strobili compact, solitary, terminal on branch tips, dorsiventrally complanate, 3.2–4.0 × 2.3–3.5 mm. Sporophylls strongly dimorphic: dorsal sporophylls ovate-lanceolate, margin denticulate, apex acuminate, with sporophyll-pteryx slightly incomplete, margin denticulate, ventral sporophylls ovate-lanceolate, ascending, carinate, margin ciliolate, apex cuspidate. Megaspores white-yellow; proximal and distal surfaces verrucate, micro-sculpture densely echinate. Microspores yellowish, proximal and distal surfaces irregularly verrucate, micro-sculpture with interconnected and blunt spinules.
Dianzhong means central Yunnan in Chinese: the type locality (Yimen) is in the central Yunnan area which is centered on the Provincial capital city Kunming.
Selaginella dianzhongensis is known only from one locality inside the Longquan Forest Park in Yimen county, with more than 300 individuals. This park has a heavy recreational load and human pressure, and there are no specific measures to protect the habitats. Considering the restricted distribution and plausible threats, we tentatively assessed Selaginella dianzhongensis as vulnerable (VU) according to the
Selaginella amblyphylla Alston: THAILAND: Payar, Doi Angka, H. M. Smith 357 – BM [BM000779901, image online!] (holotype), – US [US00134348, image online!], MICH [MICH1191432, image online!], GH [GH00022032, image online!] (isotypes), Doi Cheng Dao, 4800 ft., on rock, Oct–Nov 1922, E. Smith 1262 – SING [!, image] (paratype); Udawn, 900–1400 m, Tagawa c.s. T-1816 [PE01622140]; CHINA:Yunnan, Mengla County, B. G. Li 48926 [PE00405395]; Zhenkang W. M. Chu et al. 15204 [PE00405401]; Yunnan, Gengma, W. M. Chu et al. 15279 [PE00405408]; Guangxi, Lingui, J. X. Zhong 808194 [PE01593730]; Yunnan, Simao (Szemao), ravine, 4000 ft., A. Henry 13529 – NY [NY00127369, image online!] (paratype). Selaginella bodinieri Hieron. Guizhou, Bijie, X. C. Zhang et al. 6842 [PE 01962745]; Guangxi, Fengshan, Alt. 750 m, X. C. Zhang 1272 [PE 00405447]; Selaginella kurzii Baker, Yunnan, Cangyuan, J. C. Zhao 2000-13 [PE 00405796]; Luquan, W. M. Chu 1649 [PE 00405795]; Mengla (Cha-li-Hsien), alt. 950 m, C. W. Wang 77750 [PE 01634093].
The combined data matrix included up to 2045 nucleotides for each of the 37 taxa with 374 parsimony informative sites (374/2045 = 18.29%), consistency index (CI) = 0.66, retention index (RI) = 0.80, when the gaps were treated as missing data. The tree recovered from maximum likelihood (ML) and Bayesian inferences (BI), with bootstrap values (BS) of ML and Bayesian posterior probabilities (PP) for each clade is shown in Fig.
Morphologically, the shape and margin of ventral and dorsal leaves of Selaginella dianzhongensis is most similar to S. amblyphylla. But the axillary leaves of the former are ovate, 1.1–2.2 × 0.4–0.8 mm, margin with a few long cilia (vs. ovate or triangular, 2–3 × 0.6–1.2 mm, and denticulate at margin in S. amblyphylla). Ventral leaves of the former are ovate-oblong, apex acute (vs. oblong and obtuse or subacute at apex in S. amblyphylla), basiscopic margin entire and not ciliolate (vs. basiscopic margin sparsely ciliolate at base in S. amblyphylla), acroscopic base of ventral leaf long ciliolate (vs. shortly ciliolate in S. amblyphylla).
Molecular data showed that S. dianzhongensis clustered with two other species: S. kurzii Baker and S. bodinieri.
S. dianzhongensis is indeed similar to S. kurzii, but fertile branches are not erect (vs. erect in S. kurzii), dorsal leaves are ovate to broadly ovate with arista at apex (vs. ovate or ovate-elliptic, acuminate or aristate at apex), and ventral leaves are ovate-oblong, basiscopic margin entire and not ciliolate (vs. ovate-triangular, basiscopic margin entire or with 1 or 2 cilia at base).
Selaginella bodinieri is widely distributed in the limestone areas from central to southwestern China: main differences between this species (and the other ones mentioned above) and S. dianzhongensis are reported in the key below, and in Table
Finally, mega- and microspores of S. dianzhongensis are morphologically different from the spores of similar species studied by
Morphological characters of Selaginella amblyphylla, S. bodinieri, S. dianzhongensis and S. kurzii.
Characters | S. amblyphylla | S. bodinieri | S. dianzhongensis | S. kurzii |
---|---|---|---|---|
Main stems | creeping, up to 35 cm | erect or ascending, (15–)30–40(–50) cm | creeping, 15–25 cm | erect or ascending, 10–20 cm |
Axillary leaves | ovate or triangular, 2–3 × 0.6–1.2 mm | ovate or triangular, 2–3.2 × 0.9–1.6 mm | ovate, 1.1–2.2 × 0.4–0.8 mm | ovate or ovate-lanceolate, 1–2.5 × 0.6–1.6 mm |
Base of axillary leaf | denticulate | denticulate or ciliolate | with a few long cilia | long ciliolate |
Dorsal leaves | ovate-lanceolate or ovate, 1.4–2.2 × 0.4–0.8 mm | obliquely ovate, 2.4–3.4 × 1.2–1.8 mm | ovate to broadly ovate, 1.2–1.9 × 0.5–1.0 mm | ovate or ovate-elliptic, 1–1.2 × 0.4–0.8 mm |
Base of dorsal leaf | obliquely cordate, denticulate to ciliolate | obliquely cordate, denticulate or ciliolate | obliquely subcordate or cordate, ciliolate | subcordate or obtuse, ciliolate, |
Apex of dorsal leaf | aristate, arista ca. 1 mm long | acuminate, aristate, or cuspidate | aristate, arista 0.3–0.6 mm long | acuminate or aristate, arista 0.3–0.6 mm long |
Ventral leaves | oblong, 2.2–3.5 × 1.6–2 mm, apex obtuse or subacute | oblong-ovate or oblong, 3.4–4.4 × 1.6–2.2 mm, acute or obtuse | ovate-oblong, 1.7–3.9 × 0.7–1.6, apex acute | ovate-triangular, 1.6–3.8 × 0.6–1.6 mm, apex acute or acuminate |
Acroscopic base of ventral leaf | shortly ciliolate in basal portion, elsewhere entire | denticulate or ciliolate | long ciliolate | rather long ciliolate at base, subentire upward |
Basiscopic base of ventral leaf | sparsely ciliolate at base | entire | slightly auriculate in base, margin entire | entire or with 1 or 2 cilia at base |
Strobili | 3.5–10 × 3.2–4.4 mm | 4–16 × 1.4–2.4 mm | 3.2–4.0 × 2.3–3.5 mm | 6–8 × 2–3 mm |
Morphological characters of mega- and microspores of Selaginella amblyphylla, S. bodinieri, S. dianzhongensis and S. kurzii.
Characters | S. amblyphylla | S. bodinieri | S. dianzhongensis | S. kurzii |
Megaspores | ||||
Megaspores: proximal and distal surfaces | verrucae | verrucae | verrucae | verrucae |
Megaspores: micro-sculptures | vermiculate | spinulose | densely echinate | vermiculate |
Microspores | ||||
Microspores: proximal and distal surfaces | irregularly sized and spaced verrucae | irregularly sized and spaced verrucae | irregular size verrucae | irregularly sized and spaced verrucae |
Microspores: micro-sculptures | dense spinules | not present | blunt spinules | dense spinules |
1 | Main stems creeping or suberect, fertile stems not erect | 2 |
– | Main stems creeping, fertile stems erect | S. kurzii |
2 | Ventral leaves strongly overlapping stems and branches, basiscopic base exauriculate and margins ciliolate | S. amblyphylla |
– | Ventral leaves not overlapping stems and branches, basiscopic base slightly auriculate and margins entire or ciliolate | 3 |
3 | Plants 40–50 cm long, main stems unbranched in lower to middle part, with stolons at bases, basiscopic base of ventral leaves slightly auriculate, acroscopic base denticulate or ciliolate at margins | S. bodinieri |
– | Plants about 15–25 cm long, main stems branched from near base, rhizophores restricted to lower part of stem, basiscopic base ventral leaves entire, acroscopic base rather long ciliolate at margins | S. dianzhongensis |
We are grateful to Dr. Dmitry A. German (Heidelberg University, Heidelberg & Altai State University, Barnaul) for fruitful comments on a draft of this manuscript, Miss Huixia Dong for the line drawing, and the anonymous reviewers for their valuable comments and suggestions. This study was supported by the National Natural Science Foundation of China (NSFC, No. 31670205), and the joiner author was sponsored by CAS-TWAS President’s Fellowship for International PhD Students.
Information of the plant materials used in this study is presented in the following order: taxon name, locality (if available), collection number (if available), rbcL GenBank accession number, atpI GenBank accession number, psbA GenBank accession number references (if available). –, sequences not available. *, sequences downloaded from NCBI.
Selaginella albociliata P.S. Wang, Guizhou, China, Zhang X.-C. 7242.(PE), MH814882, MH814826, MH814854. Selaginella amblyphylla Alston, Yunnan, China, Zhang X.-C. 2924.(PE), MH814883, MH814827, MH814855. Selaginella amblyphylla Alston, Yunnan, China, Zhang X.-C. 7951.(PE), MH814884, MH814828, MH814856. Selaginella bodinieri Hieron., Chongqing, China, Zhang X.-C. 5.(PE), MH814885, MH814829, MH814857. Selaginella bodinieri Hieron., Sichuan, China, Zhang X.-C. 526.(PE), MH814886, MH814830, MH814858. Selaginella bodinieri Hieron., Guizhou, China, Zhang X.-C. 7069.(PE), MH814887, MH814831, MH814859. Selaginella chaetoloma Alston, Guizhou, China, Guo Z.-Y. 2016014.(PE), MH814888, MH814832, MH814860. Selaginella chaetoloma Alston, Guizhou, China, Zhang X.-C. 7347.(PE), MH814889, MH814833, MH814861. Selaginella chingii Alston, Guangxi, China, Zhang X.-C. 7904.(PE), MH814890, MH814834, MH814862. Selaginella chrysocaulos (Hook. & Grev.) Spring, Sichuan, China, Zhang X.-C. 86.(PE), MH814891, MH814835, MH814863. Selaginella ciliaris (Retz.) Spring, Yunnan, China, Zhang X.-C. 86.(PE), MH814892, MH814836, MH814864. Selaginella decipiens Warb., Guangxi, China, Zhang X.-C. 7253.(PE), MH814893, MH814837, MH814865. Selaginella dianzhongensis X.C.Zhang, Yunnan, China, Zhu Y.-M. 8158.(PE), MH814909, MH814853, MH814881. Selaginella drepanophylla Alston, Yunnan, China, Zhang X.-C. 8229.(PE), MH814894, MH814838, MH814866. Selaginella trichophylla K. H. Shing, Guizhou, China, Wu Y.-D. 427.(PE), MH814895, MH814839, MH814867. Selaginella heterostachys Baker, Guizhou, China, Zhang X.-C. 7088.(PE), MH814896, MH814840, MH814868. Selaginella heterostachys Baker, Guizhou, China, Zhang X.-C. 7268.(PE), MH814897, MH814841, MH814869. Selaginella kurzii Baker, Yunnan, China, Zhang X.-C. 1934.(PE), MH814898, MH814842, MH814870. Selaginella labordei Hieron. ex Christ, Hubei, China, Zhang X.-C. 3356.(PE), MH814899, MH814843, MH814871. Selaginella megaphylla Baker, Tibet, China, Jin X.-H. 19301.(PE), MH814901, MH814845, MH814873. Selaginella monospora Spring, Guangxi, China, Zhang X.-C. 7889.(PE), MH814902, MH814846, MH814874. Selaginella ornata (Hook. & Grev.) Spring, Yunnan, China, Zhang X.-C. 8520.(PE), MH814903, MH814847, MH814875. Selaginella repanda (Desv. ex Poir.) Spring, Yunnan, China, Zhang X.-C. 5655.(PE), MH814904, MH814848, MH814876. Selaginella repanda (Desv. ex Poir.) Spring, Yunnan, China, Zhang X.-C. 9273.(PE), MH814905, MH814849, MH814877. Selaginella repanda (Desv. ex Poir.) Spring, Yunnan, China, Li B.-G. sn_20.(PE), MH814906, MH814850, MH814878. Selaginella vaginata Spring, Shaanxi, China, Zhang Z.-S. 161.(PE), MH814907, MH814851, MH814879. Selaginella xipholepis Baker, Guizhou, China, Zhang X.-C. 7422.(PE), MH814908, MH814852, MH814880. Selaginella braunii Baker, voucher Zhang 1332 (PYU, CDBI), KT161420.1 *, -, -. Selaginella delicatula (Desv. ex Poir.) Alston, voucher Gao & al. HGX10734 (CDBI), KT161441.1*, -, -. Selaginella helvetica (L.) Link, voucher Zhou 093 (CDBI), KT161472.1*, -, -. Selaginella kraussiana (Kunze) A. Braun, voucher Zhou 062 (CDBI), KT161498.1*, -, -. Selaginella laxistrobila K.H. Shing, voucher Chu & al. 24449 (PYU), KT161509.1*, -, -. Selaginella nipponica Franch. & Sav., voucher Zhou & al. DJY07479 (CDBI), KT161542.1*, -, -. Selaginella remotifolia Spring, voucher Zhou 005 (PYU, CDBI), KT161580.1*, -, -. Selaginella uncinata (Desv. ex Poir.) Spring, voucher Zhang & Zhou DJY04101 (CDBI), KT161626.1*, -, -. Selaginella deflexa Brack., AF093253.1*, -, -. Selaginella selaginoides (L.) P. Beauv. ex Schrank & Mart., voucher S. Weststrand 104 (UPS), KY023148.1*, -, -.