A peer-reviewed open-access journal PhytoKeys 214: 75-82 (2022) & doi: 10.3897/phytokeys.2 14.89276 4¢Ph y toKe y S https:/ / Pp hyto keys -pen soft.net Launched to accelerate biodiversity research Argostemma ehuangzhangense (Rubiaceae), a new species from Guangdong, China Zhong-Cheng Liu'”, Jia Liu', Wan-Yi Zhao', Qiang Fan', Hua-Gu Ye’, Lei Wang’, Wen-Bo Liao! I State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China 2 College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China 3 Key Laboratory of Plant Resources Conservation and Sus- tainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China Corresponding authors: Wen-Bo Liao (Isslwb@mail.sysu.edu.cn), Lei Wang (lwang@cnu.edu.cn) Academic editor: Andre Simées | Received 25 June 2022 | Accepted 19 October 2022 | Published 30 November 2022 Citation: Liu Z-C, Liu], Zhao W-Y, Fan Q, Ye H-G, Wang L, Liao W-B (2022) Argostemma ehuangzhangense (Rubiaceae), a new species from Guangdong, China. PhytoKeys 214: 75-82. https://doi.org/10.3897/phytokeys.214.89276 Abstract Argostemma ehuangzhangense, a new Rubiaceae species from E’huangzhang Nature Reserve, Guangdong Province, China, is here described and illustrated. A morphological comparison between the new species and its putative relatives, A. lamxayanum, A. laotica and A. verticillatum, is presented. The new species is mostly similar to A. /aotica, but they can be distinguished from each other since Argostemma ehuangzhan- gense presents solitary flower (vs. 2-flowered inflorescences), flower lobes 4 (vs. 5) and anthers opening by longitudinal slits (vs. apical pores). In a preliminary IUCN Red List status of Argostemma ehuangzhangense this species is assigned as Vulnerable (VU). Keywords Argostemma ehuangzhangense, China, Guangdong, new species, Rubiaceae Introduction The genus Argostemma Wall. (Wallich 1824) belongs to the coffee family, Rubiaceae (subfamily: Rubioideae), and in its own tribe Argostemmateae (Bremer 1987; Bremer and Manen 2000). Argostemma is a large genus of more than 160 species and is widely distributed in the Old World tropics with most species occurring in SE Asia and two species in west tropical Africa (Bremer 1989; Sridith and Puff 2000; Mabberley 2017; Copyright Zhong-Cheng Liu et al. 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. 76 Zhong-Cheng Liu et al. / PhytoKeys 214: 75-82 (2022) Lanorsavanh et al. 2020). In China, six species of Argostemma were recorded (Chen and Taylor 2011). Key morphological characters of Argostemma are (i) opposite or verticillate leaves that are slightly to markedly anisophyllous, (ii) 4- or 5-merous flow- ers without nectaries, (iii) white and rotate corollas, (iv) Inner surface of corolla tube glabrous, (v) free anthers or coherent into a tube, (vi) anthers with opening by longi- tudinal slits or apical pore, and (vii) sometimes connective prolonged at the apex (Puff et al. 1995; Chen and Taylor 2011). An unknown Argostemma species was discovered during recent field surveys con- ducted between April 2017 and May 2018 at the E’huangzhang Nature Reserve, Yang- chun City, Guangdong Province. The flowers of the unknown Argostemma species are clearly 4-merous and it differs from all known Argostemma species in China. In ad- dition, we compared the unknown Argostemma from E’*huangzhang Nature Reserve against Argostemma species occurring in Southeastern Asian which presented morpho- logical characters divergent from those in our specimen. Thus, it was concluded that the unknown Argostemma from E’huangzhang Nature Reserve is a new species, which is hereby described and illustrated here. Materials and methods This study was conducted based on living and dried herbarium specimens collected from nearby Wufu Waterfall in the E’-huangzhang Nature Reserve. Herbarium speci- mens at IBSC, KEP and KUN, as well as types at IBSC, K and NY, were examined for morphological comparisons (acronyms follow Thiers 2022). Taxonomic literature of the genus for Thailand (Sridith and Puff 2000; Sridith and Larsen 2004; Sridith 2007, 2009, 2012), China (Chen and Taylor 2011), Vietnam (Vu et al. 2020), Laos (Lanorsavanh and Chantaranothai 2013, 2016, 2019; Lanorsavanh et al. 2020), and Myanmar (Kress et al. 2003; Tanaka et al. 2010) were consulted. Results Argostemma ehuangzhangense is similar to A. lamxayanum and A. laotica by sharing the following morphological features: leaves isophyllous, verticillate or pseudo-verticil- late; and leaves, pedicels, calyx and petals pubescent (Table 1). However, Argostemma ehuangzhangense is distinct from these species by its flower solitary (vs. flower (1-)2— 10); peduncles absent (vs. peduncles short or 1-3.5 cm); flower 4-merous (vs. 5-mer- ous); anther length 1.2—1.5 mm (vs. longer than 2 mm) and anthers longitudinal slits (vs. apical pore) (Table 1). Amongst the Argostemma species known in China, A. verticillatum is morphologi- cally similar to Argostemma ehuangzhangense. Argostemma verticillatum differs from the latter by its (i) glabrous stem, pedicels and calyx, (ii) inflorescence cymose and com- prised of 1-3 umbelliform, (iii) flowers 5-merous, and (iv) filaments short (Table 1). Describe a new Argostemma discovered in Guangdong, China 77 Table I. Comparison of morphological characters between Argostemma ehuangzhangense, A. lamxaya- num, A. laotica and A. verticillatum. Characters A, ehuangzhangense A. verticillatum 1-4 Plant height (cm) 2-12 1-2.5 2-10 Leaf blade shape ovate to elliptic elliptic, oblong or elliptic or lanceolate or ovate- ovate oblanceolate lanceolate [af bade sae (7a 07-23 Lateral leaf veins 3—4-paired 4—8-paired 3—4-paired 4—7-paired Leaf indumentum both surfaces antrorse | both surfaces hirsute both surfaces both surfaces strigose (abaxial sparsely pubescent glabrous or sparsely pubescent on the vein) pubescent Inflorescences flowers solitary; umbelliform,1—10- | 2-flowered; peduncles umbelliform, peduncles absent flowered; peduncles | very short, pubescent 1—3-flowered, 1—3.5 cm, glabrous composed cymose; peduncles 1-3 cm long, glabrous Pedicel 8-18 mm, pubescent | 4—12 mm, pubescent | 6-7 mm, pubescent | 5—10 mm, glabrous Caiys oles | 4, pubescent ouside 3, pubscen ouside [5 pubocentoutide [5 glabrous bo Corolla lobes 4, pubescent outside | 5, pubescent outside | 5, pubescent both |5, glabrous both side side Filament length (mm) 3.5-4 2.5-3 2.5-3.2 1-1.2 (-2.5) Anthers coherence connivent free connivent free Anther length (mm) 1.2-1.5 2.2-2.5 mm 2-3 Anther dehiscence longitudinal slits apical pores Taxonomic treatment Argostemma ehuangzhangense H.G.Ye, Jia Liu & W.B.Liao, sp. nov. urn:lsid:ipni.org:names:77309064- 1 pee Type. Cuina. Guangdong Province: Yangchun City, Bajia Town, E’-huangzhang Na- ture Reserve, near the Wufu Waterfall, 21°52'N, 111°25'E, a.s.l. 720 m, 3 May 2018, Wan-Yi Zhao, Jia Liu, Qiao-Ling Ding, Fan Ye YC-2018-02 (holotype: SYS!, Barcode SYS00236851; isotype: SYS!, Barcode SYS00236852) (Figs 1, 2). Diagnosis. Argostemma ehuangzhangense is similar to A. lamxayanum and A. laotica in its habit and pseudo-verticillate leaves, but differs in having terminal solitary 4-mer- ous flowers, short anthers (1.2—1.5 mm long) opening by longitudinal slits. Description. Terrestrial perennial herbs, 1—4 cm tall, attached to the substrate by tubers flattened globose, with a few roots. Stems erect, densely pubescent, with one pair of scale-like leaves at the lower middle portion. Leaves four per individual, clustered at the stem apex, verticillate, anisophyllous, petiole 0.5—2 long mm; blades membranous or thinly papery when dried, ovate to elliptic, 5-25 x 3-12 mm, cuneate at base, acute to obtuse at apex, margins entire; adaxial surface green, densely antrorse strigose; abax- ial surface grey-white with white particles, sparsely pubescent on the midrib vein and lateral veins; lateral veins 3- or 4-pairs; stipules deciduous. Flowers solitary, terminal; 78 Zhong-Cheng Liu et al. / PhytoKeys 214: 75-82 (2022) Figure |. Argostemma ehuangzhangense A individuals in their natural habitat B flowering individuals C fruiting individuals D side view of an individuals with tuber E leaf blade adaxial surface view F leaf blade abaxial surface view G flower, internal corolla surface view H folwer, external corolla surface view I capsule, top view J stamen K style and stigma tightly enclosed by stamens L ovary longitudinal section view. (photographs (A=G) were taken by Wan-Yi Zhao in the original habitat area of E-huangzhang and photographs (H=L) were taken by Jia Liu in SYS Herbarium in May 2018). Describe a new Argostemma discovered in Guangdong, China 79 3.5mm Figure 2. Argostemma ehuangzhangense A flower B fruit C style and stigma D habit of a mature plant E multicellular trichomes present on the stem, pedicel and ovary F corolla G organization of stamens H stamen (Drawn from living plants by Yun-Xiao Liu). 80 Zhong-Cheng Liu et al. / PhytoKeys 214: 75-82 (2022) pedicels 0.8—1.8 cm, with densely pubescent, trichomes multicellular. Calyx densely pubescent, trichomes multicellular, hypanthium portion obovoid; lobes 4, subtriangu- lar, 1-1.3 x 1.1-1.4 mm, abaxially pubescent, adaxially glabrous. Corolla white, rotate, external surface sparsely pubescent, internal surface glabrous, corolla tube 0.3-0.6 mm long; corolla lobes 4, oblong-lanceolate, 3-4 x 1.5—2 mm. Stamens 4; filaments free, 3.5—4 mm, exserted; anthers 1.2—1.5 mm long, coherent into a tube, dehiscent longi- tudinally. Ovary 2-locular, ovules numerous in each locule; style filiform, ca. 4 mm, with short pubescence, stigma capitate, exserted. Capsule obovoid, 2-5 mm in diam- eter, 1-3 mm long, pubescent, crowned by a persistent calyx, without ribs or furrows. Phenology. This species is recorded flowering in March-May and fruiting in May- September. Distribution. Argostemma ehuangzhangense is endemic to E’huangzhang Nature Reserve, southwestern Guangdong Province. It is currently known only from two pop- ulations recorded in county of Dianbai and city of Yangchun. Habitat. Growing along river on wet sandstone under the evergreen broad-leaf forest at 400-750 m a.s.l. Etymology. The specific epithet ‘ehuangzhangense’ is derived from the type local- ity, E’-huangzhang Nature Reserve of the Guangdong Province, in China. This area is the oldest geological platform in the Guangdong Province, in which many endemic species occur (Wang et al. 2003; 2004; Ding et al. 2018). The new species is also ex- pected to occur in the Yunkaishan National Nature Reserve, Maoming City, because this area shares a similar tectonic history with E’huangzhang. Therefore, we proposed for the vernacular name of the species as yuéxixuéhua (2 Py 5 4¢). Preliminary conservation status. The species is endemic to the Guangdong Prov- ince. According to our field survey, there are only two localities in which Argostemma ehuangzhangense is recorded and each population consists of 100—250 individuals. The number of mature individuals of Argostemma ehuangzhangense is more than 400, but less than 1000. ‘Thus, we believe that Argostemma ehuangzhangense would be consid- ered VU (Vulnerable) in an official IUCN Red List assessment (IUCN Standards and Petitions Subcommittee 2022) according to the D criterion. Paratypes. CHINA. Guangdong Province: Yangchun City, Bajia Town, E’huangzhang Nature Reserve, 21°52'N, 111°25'E, a.s.l. 704 m, 29 Apr. 2017, Hua- Gu Ye, Zhong-Cheng Liu YHG-06 (SYS); same locality, 5 Aug. 2017, Hua-Gu Ye, Wan- Yi Zhao, Zhong-Cheng Liu YC2017-35 (SYS); Yangchun City, Bajia Town, 21°52'N, 111°25'E, a.s.l. 750 m, 1 Aug. 2001, Hua-Gu Ye 6119 (IBSC); Dianbai County, Luo- keng Town, Shuangjifeng, 21°52'N, 111°21'E, a.s.1. 400 m, 8 Aug. 2001, Hua-Gu Ye 6427 (IBSC). Acknowledgements We are grateful to Jia-Wen Pan, Nan-Nan Liu, Qiao-Ling Ding, Fan Ye for their as- sistance during field collections. This work was partially supported by the Fourth Describe a new Argostemma discovered in Guangdong, China 81 Survey of Chinese Traditional Medicine Resources (2019-702-001; 2019-721-001) and the Guangzhou Science and Technology Program (2019.4—2022.3) under Grant (201903010076). References Bremer B (1987) The sister group of the paleotropical tribe Agrostemmateae: a redefined neotropical tribe Hamelieae (Rubiaceae, Rubioideae). Cladistics 3: 35-51. https://doi. org/10.1111/j.1096-0031.1987.tb00495.x Bremer B (1989) The genus Argostemma (Rubiaceae-Argostemmateae) in Borneo. Annals of the Missouri Botanical Garden 76: 7—49. http://www.jstor.org/stable/2399341 Bremer B, Manen JF (2000) Phylogeny and classification of the subfamily Rubioideae (Rubi- aceae). Plant Systematics and Evolution 225: 43-72. https://doi.org/10.1007/BF00985458 Chen T, Taylor CM (2011) Argostemma. In: Wu ZY, Raven PH, Hong DY (Eds) Flora of Chi- na, vol. 19. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, 75-77. http://www. iplant.cn/foc/pdf/Argostemma.pdf Ding QL, Zhao WY, Yin QY, Ye HG, Song HZ, Liao WB (2018) Begonia ehuangzhangensis (sect. Diploclinium, Begoniaceae), a new species from Guangdong, China. Phytotaxa 381(1): 107-115. https://doi.org/10.11646/phytotaxa.381.1.14 IUCN Standards and Petitions Subcommittee (2022) Guidelines for Using the IUCN Red List Categories and Criteria. Version 15. Prepared by the Standards and Petitions Subcommit- tee. https://www.iucnredlist.org/resources/redlistguidelines Kress WJ, De Filipps RA, Farr E, Kyi DYY (2003) A checklist of the trees, shrubs, herbs, and climbers of Myanmar. Contributions from the United States National Herbarium 45: 1-590. Lanorsavanh S, Chantaranothai P (2013) Two new records of Argostemma Wall. (Rubiaceae) for Laos. Thai Journal of Botany 5(1): 21-25. Lanorsavanh S, Chantaranothai P (2016) Argostemma laotica (Rubiaceae), a new species from Laos. Phytotaxa 270: 223-226. https://www.biotaxa.org/Phytotaxa/article/view/phytotaxa.270.3.7 Lanorsavanh S, Chantaranothai P (2019) Notes on the genus Argostemma (Rubiaceae) from Laos PDR. Thai Journal of Botany 47(1): 29-33. https://doi.org/10.2053 1/tfb.2019.47.1.06 Lanorsavanh S, Chantaranothai P, Souvannakhoummane K (2020) Six new species of Argostemma Wall. (Rubiaceae) from Laos. Nordic Journal of Botany 38(10): e02714. https://doi.org/10.20531/tfb.2020.48.2.16 Mabberley DJ (2017) The Mabberley’s plant-book, a portable dictionary of plants, their classification and uses. Cambridge University Press, Cambridge, 1—-1102. https://doi. org/10.1017/9781316335581 Puff C, Igersheim A, Buchner R, Rohrhofer U (1995) The united stamens of Rubiaceae. Mor- phology, Anatomy; their role in pollination ecology. Annals of the Missouri Botanical Gar- den 82: 357-382. https://doi.org/10.2307/2399888 Sridith K (2007) Notes on the genus Argostemma (Rubiaceae) of the Malay Peninsula and Pen- insular Thailand. Blumea Journal of Plant Taxonomy & Plant Geography 52: 367-377. https://doi.org/10.3767/000651907X609115 82 Zhong-Cheng Liu et al. / PhytoKeys 214: 75-82 (2022) Sridith K (2009) A new species record of Argostemma (Rubiaceae) for Thailand. Thai Forest Bulletin, Botany 37: 140-143. https://www.tci-thaijo.org/index.php/ThaiForestBulletin/ article/view/24344 Sridith K (2012) Argostemma phyllocharis, a new species of Rubiaceae from northern Thailand. Kew Bulletin 67: 85-87. https://doi.org/10.1007/s12225-012-9326-z Sridith K, Larsen K (2004) Argostemma fasciculata (Rubiaceae), a new species from Cambo- dia. Nordic Journal of Botany 23: 169-171. https://doi.org/10.1111/j.1756-1051.2003. tb00378.x Sridith K, Puff C (2000) Distribution of Argostemma Wall. (Rubiaceae), with special reference to Thailand and surrounding areas. Thai Forest Bulletin, Botany 28: 123-137. https://li01. tci-thaijo.org/index.php/ThaiForestBulletin/article/view/24959/21238 Tanaka N, Ohi-Toma T, Murata J (2010) A new species of Argostemma (Rubiaceae) from Mt. Victoria, Myanmar. Blumea Journal of Plant Taxonomy and Plant Geography 55: 65-67. https://doi.org/10.3767/000651910X499178 Thiers BM (2022) [continuously updated] Index Herbariorum: A global directory of pub- lic herbaria and associated staff. New York Botanical Garden’s Virtual Herbarium. http:// sweetgum.nybg.org/science/ih/ [accessed 18.06.2022] Vu HT, Nguyen TT, Nguyen HQ, Le KD, Do TV (2020) Notes on taxonomy of the genus Argostemma (Rubiaceae) from Vietnam. Thai Forest Bulletin (Botany) 48(2): 234-238. https://doi.org/10.20531/tfb.2020.48.2.16 Wallich N (1824) Argostemma. In: Carey W, Wallich N (Eds) Flora Indica: or Descriptions of Indian plants (Vol. 2). The Mission Press, Serampore, 324-325. Wang FM, Ye HG, Zhao NX (2003) Studies on the spermatophytic flora of E-huangzhang Nature Reserve in Yangchun of Guangdong Province. Guihaia 23(6): 495-504, 522. Wang FM, Ye HG, Ye YS, Zhou LX (2004) A preliminarily study on the pteridophytic flora of F’huangzhang Nature Neserve in Yangchun, Guangdong. Bulletin of Botanical Research, 24(3): 292-296.