$¢PhytoKeys PhytoKeys 256: 131-139 (2025) DOI: 10.3897/phytokeys.256.153110 Research Article Cardamine mangshanensis, a new species of Brassicaceae from limestone landform in Southern Hunan, China Ang Liu™®, Xiong Li?, Guo-xing Deng’, Jun Chen’, Zan Liu’, Xun-Lin Yu', Lei Wu'® 1 Central South University of Forestry & Technology, Changsha 410004, Hunan, China 2 Guangxi Forestry Inventory and Planning Institute, Nanning 530011, Guangxi, China 3 Hunan Mangshan National Nature Reserve Management Bureau, Yizhang 424221, Hunan, China Corresponding authors: Lei Wu (wuleiibk@163.com); Xun-Lin Yu (csfuyuxl@163.com) OPEN Qaceess Academic editor: Karol Marhold Received: 16 March 2025 Accepted: 27 April 2025 Published: 21 May 2025 Citation: Liu A, Li X, Deng G-xing, Chen J, Liu Z, Yu X-L, Wu L (2025) Cardamine mangshanensis, a new species of Brassicaceae from limestone landform in Southern Hunan, China. PhytoKeys 256: 131-139. https://doi. org/10.3897/phytokeys.256.153110 Copyright: © Ang Liu et al. This is an open access article distributed under terms of the Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0). Abstract Cardamine mangshanensis, anew species, is described and illustrated from the limestone landform in southern Hunan, China. The new species is similar to C. macrophylla, but differs from the latter in having more prominent tubers, shorter plant height (10-25 cm vs. 30-95 cm), fewer cauline leaves (3-4 vs. 3-18), crenate leaf margin (vs. serrate), fewer flowers (4-10 vs. 10-30), an earlier flowering period (late February to mid-March vs. April to June) and a shorter growth cycle (ca. 4 months vs. ca. 8 months). Following the IUCN Red List Criteria, C. mangshanensis is assessed as ‘Vulnerable, VU B2ab(ii)’. Key words: Cardamine, limestone landform, new species, taxonomy Introduction The genus Cardamine L. comprises approximately 300 species (https://car- damine.sav.sk), distributed on all continents except Antarctica. According to the Flora of China (Zhou et al. 2001), 48 species have been recorded in China, of which 24 are endemic. Since then, several new species of Cardamine from China have been described, including C. hunanensis (Wu et al. 2021), C. libagouensis (Diao et al. 2023), C. sichuanensis (Guo et al. 2024), C. zhangjiajieensis (Li et al. 2024), and others. Notably, some species within this genus are valued for their edible qualities. For example, in certain regions of southern China, the tender leaves of C. macrophylla Willd. are highly prized by locals for their delicate flavor. On 25 March 2020, during an investigation in Mangshan National Nature Re- serve, we discovered a unique species of the genus Cardamine. This plant had already passed its peak flowering period, with ovaries developing into nascent fruits, indicating that it was different from the plants of the same genus recorded in Hunan Province (Qi and Yu 2002; Wu et al. 2021; Li et al. 2024). To further study this unique discovery, we returned to the same site for an investigation the follow- ing year, one month in advance. On 27 February 2021, we successfully collected specimens in flowering season as planned. However, when we returned in mid- April, despite arriving half a month earlier than the previous year, we encountered the same situation: the plants had already entered a state of decay. This prevent- 131 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan ed us from observing mature fruits and seeds. Nevertheless, based on our com- prehensive understanding of its morphological characteristics and phenological patterns, we confidently conclude that this represents a new species. Material and methods The specimens are primarily deposited in the Herbarium of Forest Plants at Central South University of Forestry and Technology (CSFI). Morphological ob- servations of the new species were derived from field observations and exam- ination of herbarium specimens. Comparative analyses of related species were examined using online images from JSTOR Global Plants (https://plants.jstor. org/). The conservation status of the new species is based on field observa- tions in accordance with IUCN Red List guidelines (IUCN 2024). Taxonomic treatment Cardamine mangshanensis X.L.Yu, A.Liu & X.Li, sp. nov. urn:lsid:ipni.org:names:77362019-1 Figs 1, 2 Diagnosis. This new species is similar to C. macrophylla Willd., but it differs in the following characteristics: more prominent tubers, shorter plant height (10-25 cm vs. 20-115 cm), fewer cauline leaves (3-4 vs. 3-18), distinctly petiolulate leaflets (vs. sessile or occasionally with a short petiole), crenate leaf margin (vs. serrate), fewer flowers (4-10 vs. 10-30), white flowers (vs. purple or lilac, rarely white), an earlier flowering period (late February to mid-March vs. April to June) and shorter growth cycle in one year (ca. 3 months vs. ca. 8 months) (See Fig. 4, Table 1). Type. CHINA. Hunan: Chenzhou City, Yizhang County, Mt. Mangshan, Hejiawan, in sparse forests within limestone areas, elevation ca. 650 m, 27 February 2021, Ang Liu & You-ke Gong HJW01 (Holotype CSFI!, isotype CSFI!, HIB!&CSH!) (See Fig. 3). Description. Herbs perennial, delicate, 10-25 cm high. Rhizomes creeping, with tubers, 0.3-5 cm long. Stems erect, unbranched, surface furrowed, smooth. Cauline leaves 3-4, petiole 1.5—5 cm long, smooth, not auriculate at base, mar- gin glandular serrate; terminal leaflets elliptic or oblong, (1.5-) 2.5-4 (-5.5) x (0.5-) 1-2.5 (-3) cm, sparsely pilose, petiole 0.5-1.5 cm long, base cuneate, margin crenate, rarely doubly serrate, apex acute, slightly caudate; lateral leaf- lets 2-4 pairs, sparsely pilose, petiole 0.5-2.5 cm long, base obliquely cordate or truncate, margin crenate, equal to or slightly smaller than terminal leaflets. Racemes 4-10 flowered, dense, inflorescence slightly elongated in fruit, pedicel 0.5-1.5 cm long. Sepals elliptic, ca. 0.5 cm long, green, glabrous or very sparsely pilose. Petals white, obovate, 1 cm long, blunt at the top and cuneate at the base. Stamens glabrous, ca. 6 mm long, filaments about 4 mm long, base slightly dilat- ed, anthers purplish red. Pistils 5-7 mm long, ovary columnar, style slender, ca. 3 mm long, equal to or slightly longer than the ovary. Mature fruit not observed. Phenology. Flowering occurs from late February to mid-March. Interest- ingly, after completing seed propagation (before mid-April), the aboveground parts of the plant wither. Etymology. The specific epithet of this new species is derived from its type locality, Mt. Mangshan, one of the most famous mountains in southern Hunan. PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 132 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan Figure 1. Cardamine mangshanensis sp. nov. A habit B plants C ventral view of leaves D dorsal view of leaves E front view of flowers F rhizomes G petals H stamens I sepals. Photographs by Ang Liu. Scale bars: 1 cm. Distribution and habitat. This new species is currently known only from the limestone landform area of Mt. Mangshan, where it typically grows beneath sparse bamboo forests. Additional specimens examined (Paratypes). CHINA. Hunan: Chenzhou City, Yizhang County, Mt. Mangshan, Hejiawan, in sparse forests within limestone areas, elevation ca. 650 m, 25 March 2020, Ang Liu & Xiong Li LAH- JW01 (CSFI!, HIB! & CSH!). PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 133 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan Figure 2. Cardamine mangshanensis sp. nov. A plant and rhizomes B top view of flower C longitudinal section of flower D stamens E pistil F sepals G petals. drawn by phd jing tian; based on the holotype: ang liu & you-ke gong hjw01, csfi 076289 and living plants from type locality. PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 134 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan We = ph AS SS hs eae ab rath aL He A Sb AR TE ‘ oe TU gee ist AMIE S51 amt we raceme ce hoe Bee eles) Cee, SESE: BIRGIT as eae. Noe HES ee, faL 2: mr: PT as AE BE: 10 9g 8 OM Sheesh wae ‘Chinese Vinual Herbarium (CVH) 7 ewes 6 N HI TA 2 1 cm Holo type | Cordanuine wanghansns's XL, A La RX | Vv ype SP rev. Apna? Dot. 2) Ve POU. (2.70 Figure 3. Holotype of Cardamine mangshanensis sp. nov. (Ang Liu & You-ke Gong HJW01, CSFI 076289). PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 135 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan Figure 4. Morphological comparison of Cardamine mangshanensis sp. nov. (A1-A4) and C. macrophylla (B1-B4) A1, B1 plant A2, B2 rhizome A3, B3 Leaf A4, B4 flowers. Photographs by Ang Liu. Conservation status. Currently, only one population with a total of about 300 individuals has been found in the limestone areas of Mt. Mangshan. This population is located within the boundaries of Mangshan National Nature Reserve and is minimally affected by human activities. Based on the IUCN PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 136 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan Table 1. Comparison of morphological characters between Cardamine mangshanensis sp. nov. and C. macrophylla. Characters Cardamine mangshanensis sp. nov. Plant 10-25 cm high Rhizome with obvious tubers Cauline leaves 3-4 terminal leaflet petiole 0.5-1.5 cm long lateral leaflets 2-4 pairs petiole 0.5-2.5 cm long margin crenate base obliquely cordate C. macrophylla (20-) 30-95 (-115) cm high with tuberous knots 3-18 sessile 2-7(-11) pairs sessile or occasionally with short petiole (no more than 1 cm) margin serrate base cuneate or PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 obliquely decurrent Racemes 4-10 flowers 10-40 flowers Flower color white purple or lilac, rarely white Flowering period late February to mid-March April to June Growth cycle in one year ca. 3 months ca. 8 months Red List criteria (IUCN 2024), the conservation status of the new species should be better categorized as ‘Vulnerable, VU B2ab(ii)’. Discussion The Flora of China notes that C. macrophylla exhibits a considerable degree of variability, particularly in terms of leaflet number, shape, size, basal structure, and margin characteristics. Special attention is given to the specimen cata- loged as Henry 5635, which serves as a key reference in this context. Similar phenomena have been observed in our field studies. However, regardless of the variation in the length of the petioles of the lateral leaflets, the terminal leaf- let and the pair of lateral leaflets directly beneath it consistently lack petioles (See Fig. 5A-C). It is also evident that the terminal leaflet is positioned in close proximity to the pair of lateral leaflets below it. Through extensive field research and specimen analysis, we have confirmed that the presence of petioles in the lateral leaflets of C. macrophylla is an individual variation rather than a universal trait. Importantly, the terminal leaflet never has petioles. However, the terminal leaflet of C. mangshanensis is clearly petiolulate, mea- suring 0.5-1.5 cm in length. Additionally, the pair of lateral leaflets on its lower side are clearly not closely attached and has petioles that are 0.5-2.5 cm long (See Figs 4A3, 5D). The differences in these traits all prove that C. mangshanen- sis does not belong to the C. macrophylla complex, but is a new species. Based on our observations, we have identified a significant correlation be- tween the leaf size of this species and annual precipitation levels. In years with abundant rainfall, such as 2020, the leaves exhibit a marked increase in size, measuring approximately 3-5.5 cm in length and 1.5-2.5 cm in width. In contrast, during years with limited rainfall, such as 2021, the leaves are sig- nificantly smaller, ranging from 1.5-2.5 cm in length and 0.5-1 cm in width. This adaptive response to environmental fluctuations highlights the species’ enhanced reproductive capacity and ecological resilience. These findings provide deeper insights into the complex relationship be- tween morphological traits and environmental factors in C. mangshanensis, 137 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan 2 Nef Qa DR. AUG. HENRY'S COLLECTIONS F CENTRAL CHINA, 1885-88, WO. 5635; Figure 5. Leaf morphological variation of Cardamine macrophylla (A-C) and C. mangshanensis sp. nov. (D) A Henry 5635(GH00112001) B Henry 5635(US00100058) C Henry 5635 (K000697746) A-C from JSTOR (https://plants.jstor. org/) D from type locality of C. mangshanensis, photograph by Ang Liu. and underline its remarkable ability to thrive under varying climatic conditions in limestone landform. Acknowledgements Thanks for PhD Jing Tian’s exquisite preparation of the line drawing and PhD Hong-liang Chen's great help with this article. PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 138 Ang Liu et al.: A new species of Brassicaceae in Southern Hunan Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Funding No funding was reported. Author contributions All authors have contributed equally. Author ORCIDs Ang Liu © https://orcid.org/0000-0001-6281-7145 Lei Wu © https://orcid.org/0000-0003-1451-7855 Data availability All of the data that support the findings of this study are available in the main text. References Diao Y, Zhao CF, Chen YB, Hu ZL (2023) Cardamine libagouensis, a new species from Hubei, China. Nordic Journal of Botany 2023(8)[-e03914]: 2. https://doi. org/10.1111/njb.03914 Guo YJ, Li JL, Al-Shehbaz IA, Qian LS, Feng MJ, Yue JP, Liu QR (2024) Cardamine si- chuanensis (Brassicaceae), a new species from Sichuan, China. Phytotaxa 663(1): 15-25. https://doi.org/10.11646/phytotaxa.663.1.2 IUCN (2024) Guidelines for using the IUCN Red List categories and criteria, version 16. IUCN Standards and Petitions Committee. http://www.iucnredlist.org/resources/ redlistguidelines Li JL, Zhang C, He Y, Liu QR (2024) Cardamine zhangjiajieensis, a new species of Brassicaceae in China. PhytoKeys 248: 293-304. https://doi.org/10.3897/phytok- eys.248.119678 Qi CJ, Yu XL (2002) A survey of Hunan seed plants. Hunan Science and Technology Press, Changsha, 69-71. Wu L, Liu WJ, Mou C, Al-Shehbaz IA (2021) Cardamine hunanensis (Brassicaceae), a remarkable new species from Hunan (China) with fully bracteate racemes. Phytotaxa 512(1): 079-082. https://doi.org/10.11646/phytotaxa.512.1.7 Zhou TY, LuLL, Yang G, Al-Shehbaz IA (2001) Cardamine. In: Wu ZY, Raven PH (Eds) Flora of China, Vol. 8. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, 86-106. http://www.iplant.cn/info/Cardamine?t=foc PhytoKeys 256: 131-139 (2025), DOI: 10.3897/phytokeys.256.153110 139