Aristolochia yachangensis, a new species of Aristolochiaceae from limestone areas in Guangxi, China

Ya Jin Luo; Shi Dong Ni; Qiang Jiang; Bo Gao Huang; Yan Liu; Yu Song Huang

doi:10.3897/phytokeys.153.52796

Abstract

Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, a new species from limestone areas in Guangxi, China, is described and illustrated. It is morphologically most similar to A. fangchi Y.C.Wu ex L.D.Chow & S.M.Hwang, A. petelotii O.C. Schmidt and A. championii Merr. & Chun in shape of leaf blade, anther, gynostemium and inflorescence on old woody stems. However, it can be easily distinguished from the latter by shape of inflorescence, length of upper and lower portions of perianth tube, colour of the limb and throat. A table and a key to distinguish the new species from other morphologically similar Aristolochia species are also provided.

Keywords

Aristolochia, limestone flora, new taxa, north-western Guangxi, taxonomy

Introduction

The genus Aristolochia L. (s. l.) contains 600 species and widely distributes in tropical, subtropical and temperate regions of the world (González 2012; Zhu et al. 2019c). Based on recent studies on molecular phylogeny, chromosome and morphology of Aristolochia, some researchers have suggested that an old genus Isotrema Raf. should be reinstated to accommodate species of Endodeca Raf. and Aristolochia subgen. Siphisia (Duch.) O.C.Schmidt (Zhu et al. 2019a). However, many researchers still advise to use the name Aristolochia rather than Isotrema (Do et al. 2019; Peng et al. 2019; Cai et al. 2020). In this paper, we use the name Aristolochia to describe a new species, because the genus name Isotrema is still controversial.

Currently, there are more than 70 species of Aristolochia known from China, including many new species that have been described from Yunnan, Guangxi, Guangdong, Zhejiang and Hainan in recent years (Gong et al. 2018; Zhu et al. 2018, 2019b, 2019d; Li et al. 2019; Peng et al. 2019; Zhou et al. 2019). As one of the most biodiverse regions of China, Guangxi has 22 Aristolochia species (Peng et al. 2019; Zhu et al. 2019c), including A. bambusifolia C.F.Liang ex H.Q.Wen, A. longlinensis Yan Liu & L.Wu and A. gongchengensis,Y.S.Huang, Y.D.Peng & C.R.Lin, which are endemic in the region (Qin and Liu 2010; Huang et al. 2015; Wu et al. 2015)

During a fieldwork in Yachang Orchid National Nature Reserve of north-western Guangxi, China in April 2019, we discovered a special flowering plant of Aristolochiaceae and speculated that it might be a new species of Aristolochia, based on its flower structure. We investigated this species at the same location again and collected specimens of young capsules in May 2019. In order to obtain more detailed morphological data, we came back to the same location once again and collected specimens of mature capsules in July 2019. After consulting Flora of China (Hwang et al. 2003) and other relevant literature (Merrill and Chun 1940; Liang 1975; Chow and Huang 1975; Hwang 1981; Cheng et al. 1988; Ma 1989a, 1989b; Ma and Cheng 1989; Wen 1992; Liu and Deng 2009; Xu et al. 2011; Huang et al. 2013, 2015; Wu et al. 2013, 2015; Do et al. 2014, 2015a, 2015b, 2016, 2017, 2019; Huong et al. 2014; Zhu et al. 2015, 2016, 2017a, 2017b, 2018, 2019b, 2019d; Do and Nghiem 2017; Gong et al. 2018; Li et al. 2019; Peng et al. 2019; Zhou et al. 2019; Cai et al. 2020), as well as comparisons amongst this unknown species and its morphologically most similar species, we confirmed that this species was clearly different from the known Aristolochia species. Hence, it is here described and illustrated as a new species.

Material and methods

Field observations have been conducted in flowering and fruiting phases at the type locality more than once. Measurements and assessments of morphological characters of the new species were based on living plants in the wild and specimens gathered from the type locality. All specimens were deposited in the herbarium of Guangxi Institute of Botany (IBK), as well as the herbarium of Guangxi Botanical Garden of Medicinal Plants (GXMG). The comparisons amongst Aristolochia yachengensis B.G. Huang, Yan Liu & Y.S.Huang, A. fangchi Y.C.Wu ex L.D.Chow & S.M.Hwang, A. petelotii O.C.Schmidt and A. championii Merr. & Chun were based on the descriptions from herbarium specimens (including types) at CDBI, CSH, CZH, GXMG, GXMI, GZAC, GZTM, HEAC, HITBC, IBK, IBSC, K, KUN, NAS, PE, PEM, SM and protologues (Schmidt 1933; Merrill and Chun 1940; Liang 1975). Images of type specimens and dried herbarium specimens were gathered from JSTOR Global Plants (http://plants.jstor.org), Chinese Virtual Herbarium Website (http://www.cvh.ac.cn/) and Sharing Platform of IBK (http://www.gxib.cn/spIBK/). The materials about current habitat status and threatened factors were recorded in field observations. The assessment of risk of extinction of the new species was based on the IUCN Red List of Threatened Species Categories and Criteria and Guidelines for Using the IUCN Red List Categories and Criteria (IUCN 2001; IUCN Standards and Petitions Committee 2019).

Taxonomic treatment

Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, sp. nov.

urn:lsid:ipni.org:names:77210596-1

Figures 1, 2, 3, 4A–D

Diagnosis

Aristolochia yachangensis is morphologically similar to A. fangchi Y.C.Wu ex L.D.Chow & S.M.Hwang, A. petelotii O.C.Schmidt and A. championii Merr. & Chun, but can be distinguished from them by stems irregularly striate, sparsely yellowish-brown pubescent or glabrous; leaf blade 1.5–3 cm wide; cymes on old woody stems; basal portion of perianth tube 2–3 cm long, shorter than the upper; limb yellow, with dark purple mural–like stripes; throat yellow; capsule ellipsoid. Detailed morphological comparisons amongst the four species of A. yachangensis, A. championii, A. petelotii and A. fangchi are summarised in Table 1.

Table 1.

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Morphological comparisons of key characters amongst Aristolochia yachengensis, A. fangchi, A. petelotii and A. championii.

Characters	A. yachengensis	A. fangchi	A. petelotii	A. championii
Young stem	irregularly striate, sparsely yellowish-brown pubescent or glabrous	obscurely striate, brown villous	striate, densely spreading yellowish-brown villous	striate, densely yellowish-brown villous
Leaf blade	lanceolate to elliptic–lanceolateor linear–lanceolate, 5–15 × 1.5–3 cm, base rounded or widely cuneate, lateral veins 5–8 pairs	oblong to ovate–oblong, rarely ovate–lanceolate, 6–15 × 3–5.5 cm, base rounded or cordate, lateral veins 4–6 pairs	narrowly ovate, ovate–oblong or lanceolate–ovate, 14–22.5 × 7–13 cm, base shallowly cordate, lateral veins 4–6 pairs	lanceolate to elliptic–lanceolate or linear–lanceolate, 15–30 × 2–5 cm, base rounded or shallowly cordate, lateral veins 6–15 pairs
Pedicel	1–2 cm long, densely yellowish-brown pubescent	5–7 cm long, densely brown villous	4–4.5 cm long, densely brown villous	3–4 cm long, densely brown villous
Perianth tube	basal portion of tube 2–2.5 × 0.6–1 cm, shorter than the upper part, outside of tube mauve, densely yellowish-brown pubescent	basal portion of tube 4–5 × 1–1.5 cm, longer than the upper, outside of tube purple, with white blotches or not, densely villous	basal portion of tube 5–6.5 × 1–2 cm, longer than the upper, outside of tube pale-yellow or mauve, densely villous	basal portion of tube 5–7 × ca. 1.5 cm, longer than the upper, outside of tube mauve, densely villous
Limb	yellow, with dark purple mural–like stripes	dark purple, with white blotches	dark-purple, with white stripes	dark purple
Throat	yellow	white	milk-white mixed with black	yellow, with dark purple pots
Capsule	ellipsoid, 6–10 × 2.5–3.5 cm, glabrous	cylindrical, 5–10 × 3–5 cm, villous	narrowly ellipsoid, 10–15 × 5–8 cm, yellowish-brown villous	ellipsoid, 6–8 × ca. 3 cm, villous

Figure 1.

Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, sp. nov. A habit B flowering branch C flower (front view) D longitudinally dissected flower (showing the inside structure) E anthers and gynostemium (lateral view) F old phase of gynostemium (vertical view) G capsule. Drawn by Wenhong Lin (IBK).

Type

China. Guangxi Zhuang Autonomous Region: Baise City, Leye County, Huaping Town, Zhongjing (Yachang Orchid National Nature Reserve), 24°49.367'N, 106°24.029'E, 1341 m a.s.l., 29 July 2019, Z. C. Lu et al. 20190729YC4141 (holotype: IBK!; isotypes: IBK!, GXMG!).

Figure 2.

Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, sp. nov. A habitat B flowering branch C flowers (front view) D flower (lateral view) E flower bud F longitudinally dissected flower (showing the inside structure) G longitudinally dissected flower (dorsal view) H old phase of gynostemium (vertical view) I old phase of anthers and gynostemium (lateral view) J ovary K young capsule L mature capsule. Photographed by Shuwan Li.

Description

Shrubs climbing. Stems terete, irregularly striate, sparsely yellowish-brown pubescent or glabrous. Branchlets densely yellowish-brown pubescent. Leaf blade leathery, lanceolate to elliptic–lanceolate or linear–lanceolate, 5–15 × 1.5–3 cm, apex narrowly acuminate, base rounded or broadly cuneate, margin entire, adaxially glabrous except the pubescent midnerve and lateral veins, abaxially shallowly yellowish-brown pubescent, basal veins 3, lateral veins 5–8 pairs, conspicuous on both surfaces; petiole 1–1.5 cm long, slightly distorted, densely yellowish-brown pubescent. Cymes on old woody stems, 1–5–flowered; pedicel 1–2 cm long, pendulous, densely yellowish-brown pubescent; bracteole ovate–lanceolate, ca. 4 × 2 mm, densely yellowish-brown pubescent; perianth tube horseshoe–shaped; basal portion of tube 2–2.5 × 0.6–1 cm, shorter than the upper part, near the base of inner dark purple, densely villous, outside of tube mauve, densely yellowish-brown pubescent; upper portion of tube 2.5–3 × 0.5–0.8 cm, inner yellow, with dark purple stripes; limb subrotund–peltate, 4–6 cm in diam., yellow, with dark purple mural–like stripes, abaxially densely brown pubescent, margin shallowly 3–lobed, lobes apex mucronate; throat suborbicular, 0.5–1 cm in diam., yellow; anthers oblong, 2–4 × 1 mm, adnate to the gynostemium base, opposite to the lobes; ovary terete, ca. 1.5 × 0.3–0.5 cm, 6–angled, densely brown pubescent; gynostemium 3–lobed, margin glabrous and papillary. Capsule ellipsoid, 6–10 × 2.5–3.5 cm, 6–angled, glabrous.

Figure 3.

Holotype of Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, sp. nov. Z. C. Lu et al. 20190729YC4141(IBK).

Phenology

The new species was observed flowering from March to May and fruiting from June to August.

Etymology

The specific epithet is derived from the type locality, Yachang Orchid National Nature Reserve, Guangxi, China. The Chinese name is given as “雅长马兜铃”.

Distribution and habitat

At present, Aristolochia yachangensis was found only in Yachang Orchid National Nature Reserve of north-western Guangxi, China. It grows on limestone hillside at an elevation of ca. 1340 m. The slope direction is to the southwest, the slope is up to 40°, the tree layer is up to 15 m tall, the canopy cover is 70%, the shrub layer cover is 80% and the herb layer cover is 45%. Its associated species include Quercus variabilis Blume (Fagaceae), Celtis sinensis Pers. (Ulmaceae), Platycarya longipes Wu (Juglandaceae), Toxicodendron succedaneum (L.) Kuntze (Anacardiaceae), Yua thomsonii (Laws.) C.L.Li (Vitaceae), Pteridium aquilinum (L.) Kuhn var. latiusculum (Desv.) Underw. ex A.Heller (Pteridiaceae), Miscanthus sinensis Andersson (Gramineae) etc.

Figure 4.

A–D Aristolochia yachangensis B.G.Huang, Yan Liu & Y.S.Huang, sp. nov. A habitat B inflorescence and flowers (lateral view) C flower (front view) D anthers and gynostemium E–H A. championii Merr. et Chun: E habitat F inflorescence and flower (front view) G flower (lateral view) H anthers and gynostemium I–L A. fangchi Y. C. Wu ex L. D. Chow et S. M. Hwang: I habitat J inflorescence and flower (lateral view) K flower (front view) L anthers and gynostemium M–P A. petelotii O. C. Schmidt: M habitat N inflorescence and flower (lateral view) O flower (front view) P anthers and gynostemium. Illustration by Wenhong Lin (based on the illustrations from Flora Reipublicae Popularis Sinicae).

Conservation status

Thus far, Aristolochia yachangensis has been found only from the type locality. The only subpopulation is located within a protected region and has seven individuals, including two mature ones. Based on the present study, its Extent of Occurrence (EOO) is less than 100 km² and the known Area of Occupancy (AOO) is less than 0.5 km². According to Guidelines for Using the IUCN Red List Categories and Criteria (IUCN Standards and Petitions Committee 2019), A. yachangensis should be given a Vulnerable (VU) status, based on the criteria D2 of IUCN. As a newly-found species, however, it is probable that more subpopulations of A. yachangensis could be found in similar habitats of limestone areas of north-western Guangxi and southern Guizhou, China in the future.

Additional specimens examined (paratypes)

China. Guangxi Zhuang Autonomous Region: Baise City, Leye County, Huaping Town, Zhongjing (Yachang Orchid National Nature Reserve), 24°49.367'N, 106°24.029'E, 1341 m a.s.l., 21 April 2019, Y. J. Luo & S. W. Li 20190421001 (IBK); the same location, 17 May 2019, Y. J. Luo et al. YC4439 (IBK).

Discussion

Aristolochia yachangensis is unique in morphology. It is mostly similar to A. fangchi, A. petelotii and A. championii, but can be distinguished from all other Aristolochia species mainly based on the morphological characters of inflorescence, perianth tube, limb and throat. A. yachangensis can be further distinguished from morphologically-close species with the following key.

Key to Aristolochia yachangensis and morphologically-close species

1	Limb adaxially papillate or upper papillate, lower smooth	2
–	Limb adaxially smooth	3
2	Basal portion of tube shorter than the upper; limb adaxially yellow, with dark purple stripes	4
–	Basal portion of tube longer than the upper; limb adaxially dark purple	*A. championii*
3	Limb adaxially yellow	5
–	Limb adaxially dark purple or reddish-purple, sometimes with yellow or white blotches	6
4	Leaf blade narrowly ovate to ovate–oblong, base cordate; petiole 4–5 cm long; limb 3–4 cm in diam	*A. huanjiangensis*
–	Leaf blade lanceolate to elliptic–lanceolate or linear–lanceolate, base rounded or broadly cuneate; petiole 1–1.5 cm long; limb 4–6 cm in diam	*A. yachangensis*
5	Leaf blade ovate to narrowly ovate; limb ca. 2.5 cm in diam.; lobes of gynostemium pubescent	*A. pilosistyla*
–	Leaf blade oblanceolate to lanceolate–elliptic; limb 4–6 cm in diam.; lobes of gynostemium glabrous	*A. versicolor*
6	Limb small, ca. 3 cm × 1.5–2 cm, adaxially without blotches	*A. fulvicoma*
–	Limb large, 4–13 cm in diam	7
7	Leaf blade lanceolate–oblong or narrowly oblong, base narrowly auriculate, lateral veins 8–12; limb 8–13 cm in diam	*A. westlandii*
–	Leaf blade ovate, oblong or ovate-oblong, rarely ovate-lanceolate, base cordate or rounded; limb no more than 8 cm in diam	8
8	Leaf blade base rounded, rarely cordate; limb dark purple, with pale yellowish blotches	*A. fangchi*
–	Leaf blade base cordate; limb dark purple or reddish-purple, with white blotches or pale yellowish, without blotches	*A. petelotii*

Acknowledgements

The authors are very grateful to Mr. Wen-Hong Lin for preparing the illustration. We are also grateful to Mr. Shu-Wan Li, Mr. Ying Qin, Miss Hai-Ling Chen and Miss Zhao-Cen Lu for their assistance in fieldwork. This study was supported by the National Natural Science Foundation of China (grant no. 41661012), Special Funds for Local Science and Technology Development Guided by the Central Committee (grant no. ZY1949013), the Science & Technology Basic Resources Investigation Program of China (Grant No. 2017FY100100) and the Traditional Chinese medicine public health special project-The project of investigating and monitoring on the Chinese materia medica raw materials resources for national essential drugs ([2011]76) and Traditional Chinese Medicine industry research special project-Characteristic Chinese materia medica resources protection and utilization in representative regions of China (201207002).

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