$¢PhytoKeys PhytoKeys 252: 41-49 (2025) DOI: 10.3897/phytokeys.252.139783 Research Article Spiradiclis scorpiura (Rubiaceae), a new species from Guangxi, China You Nong™, Li-Qun Lei?®, Lei Wu®, Qi-Min Hu'®, Ying-Jing Li'!®, Xin-Cheng Qu'®, Chuan-Gui Xu™®, Gui-Yuan Wei'® 1 Guangxi Key Laboratory of Traditional Chinese Medicine Quality Standards, Guangxi Institute of Chinese Medicine & Pharmaceutical Science, No. 20-1 Dongge Road, Nanning, Guangxi, China 2 Nanning Botanical Garden, Nanning Qingxiushan Scenic and Historic Tourism Development Co., Ltd, Nanning, Guangxi, China 3 College of Forestry, Central South University of Forestry and Technology, Changsha, Hunan, China Corresponding authors: Chuan-Gui Xu (xuchuangui2021@163.com); Gui-Yuan Wei (weiguiyuan24@163.com) OPEN Qaceess Academic editor: Petra De Block Received: 20 October 2024 Accepted: 14 January 2025 Published: 10 February 2025 Citation: Nong Y, Lei L-Q, Wu L, Hu Q-M, Li Y-J, Qu X-C, Xu C-G, Wei G-Y (2025) Spiradiclis scorpiura (Rubiaceae), a new species from Guangxi, China. PhytoKeys 252: 41-49. https://doi.org/10.3897/ phytokeys.252.139783 Copyright: © You Nong 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 Spiradiclis scorpiura (Rubiaceae), a new calcareous species found in Guangxi, China, is described and illustrated. This new species is similar to S. coccinea, S. scabrida, and S. purpureocaerulea in having pubescent stems and subglobose capsules, but it is easily distinguished by its cincinnous inflorescence and its triangular, 1-2 mm long, pubes- cent bracteoles. According to the IUCN criteria, it is considered Data Deficient (DD) until more information becomes available. Photographs, an illustration, a distribution map, and a comparative table with the most similar species are provided. Key words: Daxin County, limestone, new species, sinkhole, taxonomy Introduction Spiradiclis Blume closely resembles Ophiorrhiza L., and the two genera are in the tribe Ophiorrhizeae based on morphological characteristics (Verdcourt 1958; Darwin 1976; Lo 1999; Chen and Taylor 2011; Wu et al. 2019) and mo- lecular evidence (Bremer 2009; Rydin et al. 2009; Wikstrom et al. 2013; Razafi- mandimbison and Rydin 2019). Razafimandimbison and Rydin (2019) suggest- ed that Spiradiclis is a synonym of Ophiorrhiza. However, we consider that the delimitation and relationship of the two genera still need further research, and since Spiradiclis is morphologically different from Ophiorrhiza by its linear-ob- long or subglobose capsules with four valves (vs. obcordate and compressed capsules with two valves), we prefer the traditional concept of Spiradiclis, there- by considering it separate from Ophiorrhiza. There are a total of 62 Spiradiclis species, according to Plants of the World Online (POWO 2024). They are distributed in southeastern Asia, including Bhu- tan, China, India, Indonesia, Myanmar, and Vietnam. Most of the species are distributed in China and are native to the south and southwest of the country. In the last decade, more than 20 new species of Spiradiclis have been discovered in China (e.g., Wang 2016; Zhang et al. 2018; Pan et al. 2019; Tong et al. 2020; Cai et al. 2022; Nong et al. 2024). 4 You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China During field surveys in Daxin County, Guangxi, in July 2024, a Spiradiclis popu- lation was found in flower and fruit that was morphologically similar to Spiradiclis coccinea H.S.Lo. However, this newly collected Spiradiclis is distinctly different from S. coccinea by its elliptic leaves and cincinnous inflorescence. Therefore, this population was suspected to represent a new species. This was confirmed by more observations, the examination of specimens of closely related Spiradiclis species from the herbaria PE, IBK, GXMI, and KUN, and by consulting relevant lit- erature. Hence, we confirm that the unusual plant is a species of Spiradiclis new to science, and the newly discovered taxon is here described as a new species. Materials and methods Fieldwork was carried out in Daxin County, Guangxi, to document the new species in its natural habitat. In addition, studies of herbarium material of various Spiradic- lis species were conducted at PE, IBK, GXMI, and KUN, and relevant literature was consulted (Lo et al. 1983; Wang 2002; Wang et al. 2015; Wu et al. 2015, 2016, 2019; Pan et al. 2016; Liu et al. 2017; Zhang et al. 2018; Wen et al. 2019; Li et al. 2021; Song et al. 2022). Additional related Spiradiclis species were examined based on online images from the Kew Herbarium Catalogue (http://apps.kew.org/herbcat/ gotoHomePage.do) and JSTOR Global Plants (http://plants.jstor.org/). Morpholog- ical characteristics of stems, leaves, pedicels, flowers, receptacles, gynoecia, and carpels were used to distinguish Spiradiclis species in this study. The description is based on the type specimens. Measurements were made with a tape measure and callipers. The structure of the indumentum and its dis- tribution were observed and described using a dissecting microscope at magni- fications of more than 20x. Additional information on locality, habitat, ecology, plant form, and fruits was collected in the field. The preliminary conservation threat assessment followed IUCN Categories and Criteria (IUCN 2022). Results and discussion Taxonomy Spiradiclis scorpiura Y.Nong & L.Wu, sp. nov. urn:lsid:ipni.org:names:7735651 7-1 Figs 1-4 Chinese name. xié wéi lu6 xt cdo (His EAP A). Diagnosis. Spiradiclis scorpiura is most similar to S. coccinea but is differ- ent in its densely pubescent young stems that become glabrous when older (vs. glabrous or subglabrous), its cincinnous inflorescences (vs. cymose), its triangular, 1-2 mm long, pubescent bracteoles (vs. subulate, 3-4 mm long, gla- brous), its calyx puberulent outside (vs. glabrescent outside), and its capsule 3-4 mm in diam. (vs. 4.5-5.5 mm in diam.). Type. CHINA * Guangxi, Daxin County, 22°54'06'"N, 106°50'02'E, alt. 504 m, at the rim of the top of a sinkhole, 11 July 2024, flowering, Y. Nong NY2024071101 (GXMI). (Holotype: GXMI! 051187; isotype: IBK!). Description. Subshrubs, perennial, 20-50 cm tall, rooting near base, stems ascending; stems densely pubescent when young but glabrous when old. PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 42 You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China Figure 1. Line drawing of Spiradiclis scorpiura Y.Nong & L.Wu A flowering plant B stipule C flower D long-styled flower, frontal view, showing corolla lobes and stigma E longitudinally opened long-styled flower, showing the position of the stamens and the style and stigma F longitudinally opened short-styled flower, showing the position of the stamens and the style and stigma G seed (Drawn by Xin-cheng Qu). Leaves opposite; petiole 1-2 mm long, sparsely pubescent; blade drying papery, adaxially olive green, abaxially yellowish green, elliptic, 3-7 x 0.5- 1.5 cm, sparsely pubescent or glabrous on both surfaces, margin entire, base cuneate, apex acuminate; secondary veins 8-12 on each side of the midrib, midrib concave adaxially and prominently convex abaxially; stipules triangu- lar, 1-2 mm long, glabrous outside, apex acute. Inflorescences terminal, cin- cinnous, 3-6 branched, 3—44-flowered, pubescent; peduncles 0.6-1 cm long, pubescent; pedicels short, c. 1 mm long, pubescent; bracteoles triangular, 1-2 mm long, pubescent outside. Flowers distylous. Calyx pubescent; hypan- thium portion obovate, 1-2 mm long, with 5 straight ridges; lobes 5, triangular or ovate-lanceolate, 1-1.5 mm long. Corolla purple, slenderly salverform-fun- nelform, glabrous or pubescent outside; tube 15-18 mm long, lobes broadly ovate to suborbicular, 6-8 mm long. Stamens 5. Style filiform, stigma clavate, PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 13 You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China Figure 2. Spiradiclis scorpiura Y.Nong & L.Wu A habit B detail of fruiting plant C inflorescence D stipule E longitudinally opened, long-styled flower F longitudinally opened, short-styled flower G flowering plant (photographed and edited by You Nong). PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 Ad You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China bn A RAIA AE(Record label) KE-S(No.): NY2024071101 | kn Ast} (Number of specimens): 6 4) a | K4EA (Collector): RR. BHR GUANGXI INSTITUTE OF CHINESE Pik FiiDate): aH = : A HWE MEDICINE & PHARMACEUTICAL SCIENCE | RSH (Location): BAR ARERR | | ll MN HPH(Environment): AIO HERS KE(Abundance): —ft AL (Life-form): WK #K ia (Height): | #¥. E(Branches and leaves): 4£(Flower): He fb, FE MAF (Fruits and seeds): RAZ (Family): Pe LAR} 44 (Name): | YE (Remark): SB FRR . | Figure 3. Holotype specimen of Spiradiclis scorpiura Y.Nong & L.Wu, Y. Nong NY2024071101 (GXMI! 051187). 2-lobed, lobes linear, c. 2 mm long. Long-styled flowers: corolla tube with pilose ring above stamens inside; stamens born near the base of the tube, anthers sessile or subsessile, c. 3 mm long; style c. 1.5 cm long or slight- ly longer. Short-styled flowers: corolla tube pubescent near the base inside; PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 AS You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China Dy a ast Guizhou Hunan Province Province Yunnan Province ky \ a A nw oe bo” on ; ; > Guangxi Zhuang, Autonomous Region Guangdong Ge ey 7 Province ou & Figure 4. Distribution of Spiradiclis scorpiura (red circle), S. coccinea (green triangle), S. scabrida (blue heart), and S. purpureocaerulea (purple square) in Guangxi (blue trian- gle in insert map), China. stamens born in the middle of the tube, anthers sessile or subsessile, c. 2 mm long; style c. 4mm long. Capsules subglobose, 3-4 mm in diam., glabrescent, valves 4. Seeds numerous, angular, c. 0.2 mm in diam. Phenology. Flowering and fruiting in June-July. Etymology. The specific epithet “scorpiura” refers to the terminal, cincinnous inflorescences of the new species. Distribution and habit. Known only from southeast Guangxi, China. The spe- cies has only been found at the rim of a sinkhole at elevations of 504 m. Preliminary IUCN red list category. Data available for the new species, only known from the type locality and the type specimens, are insufficient to assess its conservation status. According to the IUCN Criteria (IUCN 2022), it is consid- ered Data Deficient (DD) until more information becomes available. Spiradiclis scorpiura is currently known from a single, relatively large population. Further collection and monitoring are necessary to allow more conclusive estimations about the rarity and vulnerability of the species. Comparison with other Spiradiclis species In addition, S. scorpiura also looks similar to S. scabrida D.Fang & D.H.Qin, but is different by its shorter petioles (1-2 mm vs. 2-5 mm long), its cincinnous inflorescences (vs. corymbose-cymose), and its triangular, 1-2 mm long, pu- bescent bracteoles (vs. linear, 2-5 mm long, glabrous). Spiradiclis scorpiura is also similar to S. purpureocaerulea H.S.Lo, but it differs in its densely pubescent young stems that become glabrous when old (vs. densely pubescent young and old stems), its elliptic leaves, pubescent or glabrous on both surfaces (vs. ovate, adaxially densely strigose-hispidulous, abaxially densely pubescent), its 1-2 mm long petioles (vs. 5-20 mm long), its cincinnous inflorescences (vs. congested-cymose), and its triangular, 1-2 mm long, pubescent bracteoles (vs. narrowly lanceolate, 4-5 mm long, densely pubescent). More detailed morpho- logical differences amongst the similar species are shown in Table 1. PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 16 You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China Table 1. Main morphological differences between Spiradiclis scorpiura, S. coccinea, S. scabrida, and S. purpureocaerulea. Morphological traits Stems Leaves Length of petioles Stipules Inflorescence Bracteoles Calyx Corolla Capsule S. scorpiura densely pubescent when young but glabrous when old elliptic, sparsely pubescent or glabrous on both sur- faces 1-2 mm triangular, 1-2 mm long, glabrous outside cincinnous, 3—6-branched, pubescent triangular, 1-2 mm long, pubescent outside puberulent outside; hypan- thium portion obovate, 1-2 mm long, with 5 straight ridges; lobes trian- gular or ovate-lanceolate, 1-1.5 mm long tube 15-20 mm long, lobes broadly ovate to suborbicu- lar, 6-8 mm long subglobose, 3-4 mm in diam. S. coccinea glabrous or subglabrous narrowly elliptic-oblong or elliptic-oblong, glabrous on both surfaces 1-2mm triangular, rapidly narrowed to subulate, 4-5 mm long, glabrous outside cymose, with more than 10 flowers, pubescent subulate, 3-4 mm long, glabrous outside glabrescent outside; hypanthium portion ob- conic, 1.2-1.5 mm long; lobes narrowly lanceolate, 1.7-2 mm long tube 15-18 mm long, lobes broadly ovate to sub- orbicular, 4.5-6 mm long subglobose, 4.5-5.5 mm in diam. Acknowledgements S. scabrida pubescent to glabres- cent ovate, narrowly ovate, or lanceolate, abaxially glabrous or occasion- ally sparsely strigillose or scabridulous at least on principal veins 2-5mm subtriangular, 0.7-1 mm long, sub- glabrous outside corymbose-cymose, 3-24-flowered, pubes- cent, puberulent, or glabrescent linear, 2-5 mm long, glabrous outside puberulent out- side; hypanthium portion obovate, 1-1.5 mm long; lobes ovate-lanceolate, 1-1.5 mm long tube 25-26 mm long; lobes ovate, c. 3.5 mm long subglobose, 3-4 mm in diam. S. purpureocaerulea densely pubescent ovate, adaxially densely strigose-hispidulous, ab- axially densely pubescent 5-20 mm subulate, 2-3 mm long, pubescent outside congested-cymose, densely pubescent narrowly lanceolate, 4-5 mm long, densely pubescent outside pubescent outside; hypanthium portion ob- conic-globose, c. 2mm long; lobes narrowly lan- ceolate, 4-4.5 mm long tube 19-21 mm long; lobes subovate, c. 6 mm long subglobose, 4—4.5 mm in diam. The authors are grateful to Xiang-Chun Lan for fieldwork assistance and Xin- Cheng Qu for the line drawing (Guangxi Institute of Traditional Medical and Pharmaceutical Sciences, Nanning). Additional information Conflict of interest The authors have declared that no competing interests exist. Ethical statement No ethical statement was reported. Funding This work was supported by the Guangxi Forestry Science and Technology Promotion Demonstration Project (Guilin Kezi [2021] No. 26) and the Survey and Collection of Ger- mplasm Resources of Woody & Herbaceous Plants in Guangxi, China (GXFS—2021-34). Author contributions Data curation: YN; Funding acquisition: YN and CGX; Investigation: YN, CGX, and YGW; Methodology: YN, LQL, and YGW; Project administration: YN and YJL; Supervision: QMH, LW; Visualisation: YN, LQL, QXC; Writing—original draft: YN; Writing—review and editing: YN. PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 47 You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China Author ORCIDs You Nong ® hittps://orcid.org/0000-0001-7004-0946 Li-Qun Lei © https://orcid.org/0009-0009-7319-5439 Lei Wu © https://orcid.org/0000-0003-1451-7855 Qi-Min Hu © https://orcid.org/0009-0003-0490-3557 Ying-Jing Li © https://orcid.org/0009-0008-4849-2426 Xin-Cheng Qu © https://orcid.org/0009-0009-9078-9976 Chuan-Gui Xu © https://orcid.org/0009-0000-6263-3821 Gui-Yuan Wei © https://orcid.org/0000-0003-0652-1213 Data availability All of the data that support the findings of this study are available in the main text. References Bremer B (2009) A review of molecular phylogenetic studies of Rubiaceae. Annals of the Missouri Botanical Garden 96(1): 4-26. https://doi.org/10.3417/2006197 Cai JH, Shui YM, Song XF, Wu L (2022) Validation of the name Spiradiclis elliptica (Rubi- aceae), a new species endemic to southwestern China. Phytotaxa 545(1): 110-114. https://doi.org/10.11646/phytotaxa.545.1.10 Chen T, Taylor CM (2011) Spiradiclis. In: Wu ZY, Raven PH, Hong DY (Eds) Flora of China. Vol. 19. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, 330-339. Darwin SP (1976) The Pacific species of Ophiorrhiza L. (Rubiaceae). Lyonia 1: 48-101. IUCN (2022) Guidelines for using the IUCN Red List Categories and Criteria, version 14. Prepared by the Standards and Petitions Committee. https://www.iucnredlist.org/re- sources/redlistguidelines [Accessed 15 October 2024] Li JL, Yuan Q, Liu Y, Song XF, Pan B, Qu CH, Wu L (2021) Two new species of Spiradiclis (Rubiaceae) from limestone areas in southwestern China. Nordic Journal of Botany 39: e02979. https://doi.org/10.1111/njb.02979 Liu J, Pan B, Li SW, Xu WB (2017) Spiradiclis quanzhouensis (Rubiaceae): A new spe- cies from limestone area in Guangxi, China. Nordic Journal of Botany 36(3): e01595. https://doi.org/10.1111/njb.01595 Lo HS (1999) Spiradiclis Blume. In: Lo HS (Ed.) Flora Reipublicae Popularis Sinicae. Vol. 71(1). Science Press, Beijing, 86-110. Lo HS, Sha WL, Chen XX (1983) A revision of the genus Spiradiclis BI. Acta Botanica Austro Sinica 1: 27-36. Nong Y, Lei LQ, Wei GY, Qu XC, Zhao ZY, Feng B, Xu CG, Wu L (2024) Spiradiclis yanii (Ru- biaceae), a new species from Guangxi, China. PhytoKeys 247: 173-181. https://doi. org/10.3897/phytokeys.247.123867 Pan B, Ma HS, Wang RJ (2016) Spiradiclis pengshuiensis (Ophiorrhizeae, Rubioideae), a new species from Chongqing, China. PhytoKeys 63: 41-45. https://doi.org/10.3897/ phytokeys.63.8016 Pan B, Tu RH, Hareesh VS, Wu L (2019) Spiradiclis cavicola (Rubiaceae), a new spe- cies from limestone caves in south-western China. Annales Botanici Fennici 56(1-3): 1-4. https://doi.org/10.5735/085.056.0101 POWO (2024) Plants of the World Online. Facilitated by the Royal Botanic Gardens, Kew. https://powo.science.kew.org/results?f=&q=Spiradiclis [Accessed 18 October 2024] Razafimandimbison SG, Rydin C (2019) Molecular-based assessments of tribal and ge- neric limits and relationships in Rubiaceae (Gentianales): Polyphyly of Pomazoteae PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 48 You Nong et al.: Spiradiclis scorpiurus (Rubiaceae), a new species from Guangxi, China and paraphyly of Ophiorrhizeae and Ophiorrhiza. Taxon 68(1): 72-79. https://doi. org/10.1002/tax.12023 Rydin C, Kainulainen K, Razafimandimbison SG, Smedmark JEE, Bremer B (2009) Deep divergences in the coffee family and the systematic position of Acranthera. Plant Systematics and Evolution 278(1-2): 101-123. https://doi.org/10.1007/s00606- 008-0138-4 Song XF, Liu WJ, Chen AX, Yao ZM, Lan HB, Wu L (2022) Spiradiclis liboensis (Rubiace- ae), anew species from limestone mountain areas in Guizhou, China. PhytoKeys 204: 73-81. https://doi.org/10.3897/phytokeys.204.84397 Tong YH, Xia NH, Wu L, Vu TC (2020) Critical notes on Spiradiclis purpureocaerulea H.S. Lo (Rubiaceae) from Vietnam. Adansonia 42(19): 291-296. https://doi.org/10.5252/ adansonia2020v42a19 Verdcourt B (1958) Remarks on the classification of the Rubiaceae. Bulletin du Jardin botanique de IEtat a Bruxelles 28: 209-281. Wang RJ (2002) Two new species of Spiradiclis (Rubiaceae) from China. Novon 12(3): 420-423. https://doi.org/10.2307/3393092 Wang RJ (2016) Spiradiclis jingxiensis sp. nov. (Rubiaceae) from Guangxi, China. Nordic Journal of Botany 34(5): 550-552. https://doi.org/10.1111/njb.01134 Wang RJ, Wen HZ, Deng SJ, Zhou LX (2015) Spiradiclis danxiashanensis (Rubiaceae), a new species from south China. Phytotaxa 206(1): 30-36. https://doi.org/10.11646/ phytotaxa.206.1.5 Wen ZJ, Yang JC, Xu YF, Wu L (2019) Spiradiclis densa sp. nov. (Rubiaceae) from lime- stone areas in Guangxi, China. Nordic Journal of Botany 37(6): e02190. https://doi. org/10.1111/njb.02190 Wikstrom N, Neupane §S, Karehed J, Motley TJ, Bremer B (2013) Phylogeny of Hedyotis L. (Rubiaceae: Spermacoceae): redefining a complex Asian-Pacific assemblage. Taxon 62(2): 357-374. https://doi.org/10.12705/622.2 Wu L, Wang JL, Liu QR (2015) Spiradiclis pauciflora (Rubiaceae), a new species from limestone areas in Guangxi, China. Annales Botanici Fennici 52(3-4): 257-261. https://doi.org/10.5735/085.052.0318 Wu L, Tong Y, Pan B, Liu QR (2016) Spiradiclis glabra sp. nov. (Rubiaceae) from limestone areas in Guangdong, China. Nordic Journal of Botany 34(6): 718-721. https://doi. org/10.1111/njb.01156 Wu L, Wang BM, Pan B, Yu XL (2019) Spiradiclis tubiflora (Rubiaceae), a new cave-dwell- ing species from southern China. PhytoKeys 130: 217-224. https://doi.org/10.3897/ phytokeys.130.34625 Zhang F, Liu Y, Wen ZJ, Wu L (2018) Spiradiclis lui,a new species of Rubiaceae from Guangxi, China. Nordic Journal of Botany 36(6): e01786. https://doi.org/10.1111/njb.01786 PhytoKeys 252: 41-49 (2025), DOI: 10.3897/phytokeys.252.139783 49