Research Article |
Corresponding author: Hong Liu ( liuhong@scuec.edu.cn ) Academic editor: Alina Freire-Fierro
© 2021 Long-Fei Fu, Tian-Ge Yang, De-qing Lan, Fang Wen, Hong Liu.
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:
Fu L-F, Yang T-G, Lan D-q, Wen F, Liu H (2021) Chrysosplenium sangzhiense (Saxifragaceae), a new species from Hunan, China. PhytoKeys 176: 21-32. https://doi.org/10.3897/phytokeys.176.62802
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Chrysosplenium sangzhiense Hong Liu, a new species from Hunan, China, is described and illustrated. The phylogenetic analysis revealed that the new species belongs to subgen. Chrysosplenium and is closely related to C. grayanum, C. nepalense and C. sinicum. The chromosome number of the new species is 2n = 46, indicating a novel basic number x = 23 in Chrysosplenium that is different from other species. This also suggests that C. sangzhiense is probably an allopolyploid derivative of a species with x = 11 and one with x = 12. Morphologically, C. sangzhiense can be easily distinguished from C. grayanum, C. nepalense, C. sinicum and C. cavaleriei, a species not included in our phylogenetic analysis by a suite of characters relating to the sterile shoots, basal leaves, cauline leaves, flowering stem, sepals, disc, capsule and seed. A global conservation assessment is performed, and classifies C. sangzhiense as Least Concern (LC).
Chrysosplenium, cytology, phylogeny, Saxifragaceae, subgen, taxonomy
Chrysosplenium L. (1753) is a perennial herbaceous genus in Saxifragaceae and comprises more than 70 species (
The latest revision of Chinese Chrysosplenium included 35 species (
Previous studies have demonstrated that Chrysosplenium has a diverse basic chromosome number with x = 7, 8, 9, 10, 11, 12 and 13 at species level indicating cytological data provides important evidence for the delimitation and evolution of Chrysosplenium (
As part of ongoing research into the diversity of Chinese Chrysosplenium, the authors undertook an extensive fieldtrip in Hunan, China. During the trip an unknown species of Chrysosplenium was collected. Following a thorough literature survey (
All morphological characters were studied based on the material from field and herbarium specimens using a dissecting microscope (SMZ171, Motic, China). For seed morphology, we also undertook scanning electron micrograph (SEM) observation; seeds were collected from the field and dried by silica gel. The pre-treatment including impurities removing, air-drying and gold-coating was performed, following
To confirm the systematic position of this unknown species, we conducted phylogenetic studies using matK sequence data. We chose this DNA region due to its highest species coverage within the genus (
Species names and GenBank accession numbers of matK DNA sequences used in this study (* newly generated sequences).
Species | Location | Voucher specimens | Herbarium | Genbank number |
---|---|---|---|---|
Chrysosplenium album Maxim. | Nikkou-shi, Japan | HSN09815 | HSN | MW402998 * |
Chrysosplenium aureobracteatum Y.I.Kim & Y.D.Kim | Gangwon, South Korea | KYI-2009032 | – | AXY64019 |
Chrysosplenium biondianum Engl. | Shanxi, China | HZ2017050107362 | HSN | MW402999 * |
Chrysosplenium carnosum Hook.f. et Thoms. | Sichuan, China | HSN013113 | HSN | MW403000 * |
Chrysosplenium davidianum Decne. ex Maxim. | Sichuan, China | HSN06442 | HSN | MW403001 * |
Chrysosplenium delavayi Franch. | Hunan, China | SZ2016080907105 | HSN | MW403002 * |
Chrysosplenium echinus Maxim. | Nikkou-shi, Japan | HSN09817 | HSN | MW403003 * |
Chrysosplenium fauriae Franch. | Nikkou-shi, Japan | HSN09823 | HSN | MW403004 * |
Chrysosplenium flagelliferum Fr. Schmidt. | Nikkou-shi, Japan | HSN09816 | HSN | MW403005 * |
Chrysosplenium forrestii Diels | Nikkou-shi, Japan | HSN7797 | HSN | MW403006 * |
Chrysosplenium giraldianum Engl. | Sichuan, China | JZ2018042507981 | HSN | MW403007 * |
Chrysosplenium glossophyllum Hara | Sichuan, China | QCS2017102608035 | HSN | MW403008 * |
Chrysosplenium grayanum Maxim. | Nikkou-shi, Japan | HSN09810 | HSN | MW403009 * |
Chrysosplenium griffithii Hook.f. et Thoms. | Shanxi, China | HSN7760 | HSN | MW403010 * |
Chrysosplenium henryi Franch. | Hunan, China | HSN7505 | HSN | MW403011 * |
Chrysosplenium hydrocotylifolium Lévl. et Vant. | Hubei, China | HSN09188 | HSN | MW403012 * |
Chrysosplenium japonicum (Maxim.) Makino | Zhejiang, China | HSN7909 | HSN | MW403013 * |
Chrysosplenium kamtschaticum Fisch. ex Seringe | Shimane-ken, Japan | DG2019032310004 | HSN | MW403014 * |
Chrysosplenium kiotense Ohwi. | Nikkou-shi, Japan | HSN09818 | HSN | MW403015 * |
Chrysosplenium lanuginosum Hook.f. et Thoms. | Anhui, China | BD2017030507343 | HSN | MW403016 * |
Chrysosplenium lectus-cochleae Kitagawa | Jilin, China | HSN7379 | HSN | MW403017 * |
Chrysosplenium macrophyllum Oliv. | Hubei, China | BD2017030507344 | HSN | MW403018 * |
Chrysosplenium macrospermum Y.I.Kim & Y.D.Kim | Jilin, China | CBS2016062406656 | HSN | MW403019 * |
Chrysosplenium macrostemon Maxim. ex Franch. et Sav. | Nikkou-shi, Japan | HSN09820 | HSN | MW403020 * |
Chrysosplenium nepalense D.Don | Yunnan, China | GLGH20170607375 | HSN | MW403021 * |
Chrysosplenium nudicaule Bunge | Gansu, China | HSN07772 | HSN | MW403022 * |
Chrysosplenium pilosum Maxim. | Nikkou-shi, Japan | HSN09819 | HSN | MW403023 * |
Chrysosplenium qinlingense Z.P.Jien ex J.T.Pan | Sichuan, China | HSN7980 | HSN | MW403024 * |
Chrysosplenium ramosum Maxim. | Jilin, China | SJH2017052107372 | HSN | MW403025 * |
Chrysosplenium serreanum Hand.-Mazz. | Jilin, China | SJH2017052107371 | HSN | MW403026 * |
Chrysosplenium sinicum Maxim. | Hunan, China | TPS2017042407504 | HSN | MW403027 * |
Chrysosplenium taibaishanense J.T.Pan | Shanxi, China | HSN7761 | HSN | MW403028 * |
Chrysosplenium uniflorum Maxim. | Tibet, China | HSN7380 | HSN | MW403029 * |
Chrysosplenium zhouzhiense Hong Liu | Shanxi, China | HSN13356 | HSN | MW403030 * |
Chrysosplenium sangzhiense Hong Liu sp. nov. | Hunan, China | TPS2017042307449 | HSN | MW403032 * |
Chrysosplenium alternifolium L. | Shimane-ken, Japan | DG2019032310003 | HSN | MT362050 |
Chrysosplenium maximowiczii Franch. et Sav. | Kanagawa, Japan | – | – | AB003053 |
Chrysosplenium nagasei Wakab. & H.Ohba | Gifu, Japan | – | – | AB003054 |
Chrysosplenium rhabdospermum Maxim. | Nagasaki, Japan | – | – | AB003058 |
Chrysosplenium tosaense Makino | Saitama, Japan | – | – | AB003059 |
Chrysosplenium iowense Rydb. | Iowa, USA | – | – | L34120 |
Chrysosplenium oppositifolium L. | Wales, UK | – | – | JN894973 |
Chrysosplenium rosendahlii Packer | Northwest Territories, Canada | – | – | KC474470 |
Chrysosplenium tetrandrum (N. Lund) Th. Fries | Nunavut, Canada | Brysting_01-065_CAN | CAN | KC474473 |
Chrysosplenium wrightii Franch. & Sav. | Yukon, Canada | Bennett_08-125_CAN | CAN | KC474474 |
Chrysosplenium americanum Schwein. ex Hook. | Hatfield, New Hampshire, USA | – | – | KU524206 |
Chrysosplenium valdivicum Hook. | Chile | – | – | KU524208 |
Chrysosplenium zhangjiajieense X.L.Yu, Hui Zhou & D.S.Zhou | Hunan, China | ZJ2016031506369 | HSN | MW402997 * |
Saxifraga stolonifera Curt. | Anhui, China | HSN07355 | HSN | MW403031* |
Itea chinensis C.K.Schneider | – | – | – | NC_037884 |
Itea virginica L. | – | – | – | MF350096 |
We performed phylogenetic analyses of Chrysosplenium based on matK sequence dataset using Bayesian inference (BI) and maximum likelihood (ML). For BI analysis, we employed MrBayes v.3.2.6 (
We conducted the ML analysis using IQ-TREE v 2.0.6 (
Living plants of the new species were cultivated in the green house of South-Central University for Nationalities. Actively growing root tips were harvested after 1–2 weeks. Cytological examination was performed following
The aligned matrix of matK sequence was 1,644 characters. Of the 154 variable characters, 90 (58.44%) were parsimony-informative, including indels. BI and ML analyses resulted in the same tree topology which showed the undescribed species as belonging to a strongly supported clade (BP = 89%, PP = 1) that included Chrysosplenium grayanum Maxim. (1877), C. nepalense D.
The chromosome number of Chrysosplenium sangzhiense was observed to be 2n = 46 (Fig.
Similar to Chrysosplenium grayanum, C. nepalense, C. sinicum and C. cavaleriei (Table
Morphological comparison of Chrysosplenium sangzhiense, C. cavaleriei, C. grayanum, C. nepalense and C. sinicum.
Characters | C. sangzhiense | C. cavaleriei | C. grayanum | C. nepalense | C. sinicum |
---|---|---|---|---|---|
Sterile branch | from all leaf axils | from near stem base | from all leaf axils | from all leaf axils | only from basal leaf axils |
Basal leaves | absent | absent | absent | absent | present |
Cauline leaves | 2–3 pairs, 10–30 × 10–25 mm | 1–3 pairs, 9–13 × 10–14 mm | 2–7 pairs, 4–17 × 4–17 mm | 3–5 pairs, 3–18 × 5–18 mm | 1–2 pairs, 6–10.5 × 7.5–11.5 mm |
Flowering stem (upper part) | square | unknown | rounded | rounded | square |
Sepals | erect | spreading | erect | erect | erect |
Disc | absent | distinct | somewhat inconspicuous | absent | absent |
Capsule lobe | lobes conspicuous unequal | lobes conspicuous unequal | lobes conspicuous unequal | lobes subequal | lobes conspicuous unequal |
Seed | red brown, papillose | dark brown, papillose | dark brown, papillose | red brown, smooth | dark brown, papillose |
China. Hunan: Badagongshan National Nature Reserve, Sangzhi County, 29°47'10"N, 110°5'33"E, under broadleaved forests and near the stream in a mountain area at ca 1,220 m altitude, 22 April 2017, Hong Liu HSN07449 (holotype HSN; isotypes HSN, IBK).
Perennial herbs, 10–25 cm tall. Root fibrous and robust. Rhizome long creeping without stolons or bulbs. Basal leaves absent. Sterile shoots well developed, arising from all leaf axils, round in cross-section, 5–15 cm long at anthesis, later elongate and decumbent, up to 50 cm long, rooting at nodes, without forming a rosette. Leaves of sterile shoots opposite, isophyllous, always ca 8 at anthesis, dark purple, petiole 6–10 mm long, blade 10–30 × 10–25 mm, rounded, glabrous, apex obtuse, margin obtusely dentate (10–16 teeth), base broadly cuneate; post-anthesis 10–30 or more, green, petiole 6–10 mm long, blade 20–35 × 15–20 mm, rounded or ovate, glabrous, apex obtuse, margin obtusely dentate (12–20 teeth), base broadly cuneate. Cauline leaves 4–6 (2–3 pairs), opposite, petiole 6–10 mm long; blade 6–13 × 5–12 mm, rounded or broadly ovate, glabrous, apex obtuse, margin obtusely dentate (10–14 teeth), base broadly cuneate. Flowering stem(s) erect, branched, 10–23 cm tall, glabrous, purple, square in cross-section. Inflorescence 8–25-flowered cyme, dense, 1.4–9 cm long, 5–10 cm in diam.; bracteal leaves yellow-green, triangular arrangement and unequal, the middle one larger, petiole 2–8 mm long, blade 4–15 × 7–10 mm, subrounded, glabrous, apex obtuse, margin obtusely dentate (6–12 teeth), base broadly cuneate; Flowers tetramerous, actinomorphic; sepals 4 (2 pairs), erect, yellow in flowering phase but turn green in fruiting time, 2–3 × 2–3 mm, broadly ovate, apex obtuse; disk absent; stamens 8, homostylic, 1–2 mm long, shorter than sepals; filaments slender, ca 1 mm long; anther yellow, 2-locular, longitudinally dehiscent; ovary 2-locular, semi-inferior; stigma 2; styles erect, ca 1–2 mm long. Fruit a capsule, 5–7 mm long, green, smooth, 2-lobed (horn-shaped), conspicuous unequal, dehiscent along the adaxial suture; seeds numerous, reddish brown, sub-ovoid, a raphe on one side, 650–800 × 600–750 μm, papillose.
Chrysosplenium sangzhiense is named after the type locality, Sangzhi County, Hunan Province, China.
sāng zhí jīn yāo (Chinese pronunciation); 桑植金腰 (Chinese name).
At present, Chrysosplenium sangzhiense is only known from a single locality (IUCN criterion D2). At this locality, the population is ca 500 mature individuals (IUCN criterion D1) growing in at least ten patches within a nature reserve. Using the IUCN methodology, C. sangzhiense would be classed as Vulnerable (VU), however no plausible threat could be found to confirm its status as the population is located within a protected area and not under threat in the near future. In addition, considering that the surrounding area has not been completely explored, there may be hitherto undocumented additional populations. For these reasons the Global Species Conservation Assessment for C. sangzhiense is Least Concern (LC).
Macro- and micro-morphology of Chrysosplenium spp. A C. sangzhiense, habit (A1), inflorescence with flowers (A2), scanning electron micrograph (SEM) of seed 200× (A3), 1,000× (A4) B C. grayanum, habit (B1), inflorescence with flowers (B2), SEM of seed 150× (B3), 1,000× (B4) C C. nepalense, habit (C1), inflorescence with flowers (C2), SEM of seed 150× (C3), 1,000× (C4) D C. sinicum habit (D1), inflorescence with flowers (D2) SEM of seed 150× (D3), 1,000× (D4) (Photos by Hong Liu).
Our phylogenetic analysis is consistent with previous studies (
The basic chromosome number of Japanese Chrysosplenium species is x = 11 or x = 12, but in China there is more diversity with x = 7, 8, 9, 10, 12 and 13 (
In this study, we confirm and describe a new species of Chrysosplenium based on morphological, molecular and cytological evidence. The newly generated molecular data contributes to reconstruct a robust phylogenetic framework for further studies on the aspects of biogeography and character evolution of Chrysosplenium. In addition, a novel basic chromosome number for Chrysosplenium reported here will be useful data to evaluate the evolutionary pattern of chromosome number change and to estimate the basic chromosome number of clades of the genus.
This work was supported by the construction plan of Hubei province science and technology basic conditions platform (No.2017BEC014), Fund for key laboratory construction of Hubei province (No.2018BFC360) and the major projects of technological innovation in Hubei province (2019ABA101).