Vincetoxicum pingtaoanum (Apocynaceae: Asclepiadeae), a new species from the Three Gorges District in Central China

Abstract

Vincetoxicum is one of the largest genera in Apocynaceae with recent expansion that includes former Tylophora, Biondia, and other small genera. In this study, we describe Vincetoxicum pingtaoanum sp. nov., a new woody species of Apocynaceae from the Three Gorges District in Central China based on our recent field and old herbarium collections. It is unique due to its growth habit and leaf characteristics which is similar to the former Biondia species. However, it has the well-developed corona common to the former Tylophora species. Diagnostic characteristics, a full description, photographs, ecology, and a distribution map and conservation status of the new species are provided in this study. Detailed comparisons with similar species and a key to all known species of Vincetoxicum from the Three Gorges District are also provided.

Full text

Phytotaxa 564 (1): 059–070
https://www.mapress.com/pt/
Copyright © 2022 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Michele Rodda: 19 Aug. 2022; published: 14 Sept. 2022
https://doi.org/10.11646/phytotaxa.564.1.4
59
Vincetoxicum pingtaoanum (Apocynaceae: Asclepiadeae), a new species from the
Three Gorges District in Central China
CAI-FEI ZHANG1,2,6#, YAN WANG1,2,3,7#, FENG CHEN4,8#, HOU-LIN ZHOU5,9, MIAO LIAO1,2,10, WYCLIF
OCHIENG ODAGO1,2,3,11, GUANG-WAN HU1,2,3,12* & QING-FENG WANG1,2,3,13
1 CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sci-
ences, Wuhan 430074, China.
2 Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 430074, China.
3 University of Chinese Academy of Sciences, Beijing 100049, China.
4 Chongqing Museum of Natural History, Chongqing 400799, China.
5 Forestry Bureau of Wushan County, Wushan, Chongqing 404700, China.
6
�
zhangcf@wbgcas.cn; https://orcid.org/0000-0002-2818-5751
7
�
wangyan@wbgcas.cn; https://orcid.org/0000-0002-8818-0282
8
�
fengchen408@163.com; https://orcid.org/0000-0003-3398-8900
9
�
674393605@qq.com; https://orcid.org/0000-0002-2566-1345
10
�
1010995901@qq.com; https://orcid.org/0000-0003-2545-9419
11
�
wyclifodago88@gmail.com; https://orcid.org/0000-0001-7014-7815
12
�
guangwanhu@wbgcas.cn; https://orcid.org/0000-0001-7728-7976
13
�
qfwang@wbgcas.cn; https://orcid.org/0000-0001-9143-8849
# These authors contributed equally to this work.
*Author for correspondence:
�
guangwanhu@wbgcas.cn
Abstract
Vincetoxicum is one of the largest genera in Apocynaceae with recent expansion that includes former Tylophora, Biondia,
and other small genera. In this study, we describe Vincetoxicum pingtaoanum sp. nov., a new woody species of Apocynaceae
from the Three Gorges District in Central China based on our recent field and old herbarium collections. It is unique due to
its growth habit and leaf characteristics which is similar to the former Biondia species. However, it has the well-developed
corona common to the former Tylophora species. Diagnostic characteristics, a full description, photographs, ecology, and
a distribution map and conservation status of the new species are provided in this study. Detailed comparisons with similar
species and a key to all known species of Vincetoxicum from the Three Gorges District are also provided.
Keywords: Biondia, China, plant taxonomy, Tylophora, Tylophorinae, Vincetoxicum
Introduction
Vincetoxicum Wolf (1776: 130) is a large genus in the family Apocynaceae ranging through the tropical and subtropical
Africa, Asia, and Oceania with some species extending into temperate Eurasia and some aggressively invasive in
North America (Liede-Schumann et al. 2016; Endress et al. 2018). Formerly subsumed under Cynanchum Linnaeus
(1753: 212) or treated as a section of Cynanchum (e.g., Tsiang & Li 1977; Li et al. 1995), Vincetoxicum has been
resurrected with strong support from morphological and chemical evidence (Qiu et al. 1989; Liede 1996) as well as
molecular studies (Civeyrel et al. 1998; Sennblad & Bremer 2000; Liede 2001; Potgieter & Albert 2001). Moreover,
recent molecular studies led to a much expanded Vincetoxicum including Tylophora Brown (1810: 460) and several
other smaller genera (Liede et al. 2002; Yamashiro et al. 2004; Liede-Schumann et al. 2012; Liede-Schumann et al.
2016). Accordingly, many new combinations and replacement names have been created in recent years (Kidyoo &
Kidyoo, 2018; Liede-Schumann & Meve 2018; Hsu et al. 2021). The redefined Vincetoxicum can be recognized by the
usually clear latex, rather small corollas (usually no more than 1 cm long), and corona with free or connected stamina
lobes (Endress et al. 2018).

ZHANG ET AL.
60 • Phytotaxa 564 (1) © 2022 Magnolia Press
China is one of the main diversity centers of Vincetoxicum. According to the current circumscription of Vincetoxicum,
all species of Belostemma Wall. ex Wight (1834: 52), Biondia Schlechter in Diels (1905: 91), Merrillanthus Chun &
Tsiang (1941: 105), Pentastelma Tsiang & Li (1974b: 577), Tylophora and Cynanchum sect. Vincetoxicum Tsiang &
Li (1974a: 94) treated in Flora Repubulicae Popularis Sinicae (Tsiang & Li 1977) and Flora of China (Li et al. 1995)
have been transferred to Vincetoxicum. Later, six new species have been found from China (Tseng et al. 2011; Jiang et
al. 2018; Hsu et al. 2021; Shah et al. 2021; Zeng et al. 2021; Ye et al. 2022) and V. taiwanense (Hatusima 1963: 10)
T.C. Hsu in Idrees & Hsu (2021: 177) from Taiwan has been reinstated as a distinct species (Hsu et al. 2021; Idrees &
Hsu 2021). Thus, nearly 90 species of Vinecetoxicum s.l. are hitherto known from China.
The Three Gorges District in Central China in a broad sense encompasses a large distinct area around the mid-
Yangtze River with high and endemic biodiversity, ranging from East to Yichang of Hubei Province, West to Chongqing,
North to Daba Mountains, and South to Wuling Mountains (Zheng, 1994). This district is a core region of Central China
plant diversity hot spot (Ying 2001), also known as Eastern Sichuan (Chongqing)—Western Hubei endemic centre of
plant genera (Ying 1996). During field collections in the Three Gorges District in recent years, we photographed and
collected unknown plant species from Fengjie, Wushan, and Wuxi counties (Figure 1). The clear latex, tiny, and rotate
corollas shows that this species belongs to the genus Vincetoxicum. We also found an old herbarium collection Hong-
Fu Zhou & He-Yi Su 107855 (IBSC [0521747, 0521748]) from a neighboring locality with the same identity. Based on
literature review, more field collections in China, and studies of specimens from different herbaria, we concluded that
the above materials represent a species new to science.
FIGURE 1. Distribution of Vincetoxicum pingtaoanum Cai F. Zhang, G.W. Hu & Q.F. Wang in the Three Gorges in Central China.
Materials and methods
Specimens of Vincexoxicum s.l. at CANT, CDBI, E, EMA, HIB, HHBG, HZU, IBSC, KUN, NAS, PE, SM, SZ, and
ZM (herbarium acronyms follow Thiers (continuously updated)) were carefully checked during the herbaria visits.
Other specimen images were examined through the Chinese Virtual Herbarium (CVH, http://www.cvh.ac.cn) and the
Global Biodiversity Information Facility (GBIF, https://www.gbif.org/). Several field collections were conducted in
Southern and Central China and morphologically similar species were collected for comparison. Fresh flowers were
dissected and photographed under a stereomicroscope Nikon SMZ25 (Wuhan, China). Floral characteristics were
measured using fresh materials and those kept in FAA solution. The distribution map was generated using ArcGIS
10.2 (ESRI 2013). The conservation status of the new species was assessed according to the IUCN guidelines (IUCN
2017).

VINCETOXICUM PINGTAOANUM (APOCYNACEAE) Phytotaxa 564 (1) © 2022 Magnolia Press • 61
Taxonomic treatment
Vincetoxicum pingtaoanum Cai F. Zhang, G.W. Hu & Q.F. Wang, sp. nov. (Figures. 2–4 and 5: A).
Vincetoxicum pingtaoanum is similar to V. henryi, but it can be easily distinguished by the longer petioles (5–16 mm vs. 2–3 mm), long
inflorescences (2.5–6 cm vs. 1–2 cm) with a rachis (vs. without a rachis and umbel-like) that are mostly longer (vs. shorter) than
leaves, greenish-yellow (vs. purplish red) corollas with linear-lanceolate lobes ca. 5 mm (vs. triangular-ovate less than 2 mm) long
(Figure 5). Additionally, it is similar to V. emeiense based on the corolla shapes, but differs in the yellowish green (vs. yellowish
brown) corollas, shorter inflorescences (2.5–6 cm vs. 7–11 cm), coronas attached above the upper half gynostegia (vs. inserted near
base of gynostegia) with obtuse (vs. truncate) lobes (Figure 5), and horizontal (vs. ascending) caudicles.
Type:—CHINA. Chongqing City, Wuxi County, Lanying, Lanying Grand Canyon, 109.835471°E, 31.437667°N, 758 m a.s.l., path side
and on rocks in the valley, 13 April 2021, Feng Chen, Hou-Lin Zhou, Xue-Bing Shi et al. YTL20-409 (Holotype: HIB ! [HIB0208169];
isotypes: CQNM!, PE!).
Evergreen woody lianas. Stems green, 1–1.5 mm in diameter, striated, glabrous except for a ring of trichomes around
the nodes. Petioles 5–16 mm long, purplish, adaxially densely puberulent along the two sides of the grove, glabrescent
when old, uppermost with 4–6 glands; leaf blades thinly coriaceous, lanceolate, lanceolate-ovate, sometimes ovate
or elliptic especially when young, green, reddish when young, lower older ones 6–8 × 2.2–3 cm, upper ones 2.2–6.5
× 0.8–1.6 cm; base obtuse, cuneate or rounded, apex attenuate to acuminate, sometimes acute; midrib raised on both
surfaces, lateral veins 4 –5 pairs, obscure in younger ones, glabrous except for a few trichomes on main vein, veins of
older leaves prominently pale and reticulate. Inflorescences slender, with (2–) 9–14 flowers, 2.5–6.5 cm long, mostly
with two cymules (each with 4–6 flowers) separated by a rachis, rarely 2- or 3-branched and zigzagging, usually
longer than the adjacent leaves; peduncles 17–34 mm, longer than pedicles, glabrous; bracteoles ciliate. Pedicels
slender 13–23 mm, purplish, glabrous. Calyx lobes purplish, triangle-ovate, ca. 1.5 × 0.7 mm, abaxially sparsely
puberulent, each with a dark brown gland between adjacent lobes. Corolla yellowish green, purplish at the throat,
deeply lobed, starfish-like, ca. 1 cm in diameter, slightly convex, exterior glabrous, interior minutely hairy; lobes
spreading, twisted clockwise, ca. 5 × 1 mm, linear-lanceolate, margins revolute, apex rounded. Gynostegium green ca.
2 mm tall. Staminal corona 2–2.3 mm in diameter; lobes fleshy, ovoid, dorsally rounded, ca. 0.5 mm long, radiating
from the stamina column and adnate to the upper half of the anthers. Anthers oblong-rhomboid, apex broadly triangular,
subacute, inflexed; anther wings 0.5 mm long; apical appendages with conspicuous membranous margin. Pollinarium
with two pollinia connected via caudicles to corpusculum; corpuscular narrowly ellipsoid, brownish, ca. 0.12 × 0.04
mm; caudicles horizontal, fusiform, 0.1 mm long; pollinia oblong-reniform, ca. 0.2 × 0.14 mm, apically attached to
caudicles. Style-head flat. Follicles single or paired, narrowly fusiform, brownish, 52–55 × 5–6 mm, glabrous. Seeds
brownish-black, ca. 7 × 2–2.5 mm, bottle-shaped, much compressed with one side nearly flat and slightly convex &
papillose on the other, margins thinner; coma 15–21 mm long.
Etymology:—The specific epithet ‘pingtaoanum’ is in honor of Prof. Ping-Tao Li (李秉滔, P.T. Li; 1936– ) from
South China Agriculture University, for his contributions to the taxonomy of Chinese Apocynaceae.
Vernacular name:—Following a tradition of using geographic names as part of the plant vernacular names, we
suggest ‘Three Gorges swallow-wort’ as the English common name and ‘Sanxia Baiqian (三峡白前)’ as the common
Chinese name for the new species.
Habitat:—300–1200 m a.s.l, growing on rocks in open or semi-open areas.
Phenology:—Flowering from April to August; exact fruiting period unknown, but the last growing season’s fruits
with mature seeds can be found in April.
Distribution and conservation status:—V. pingtaoanum is currently known only from five localities in the
Three Gorges District in Central China (Fig. 1). Three localities are in the north of Yangtze River in Wushan and Wuxi
Counties, while the other two are in the south of Yangtze River in Fengjie County. The direct distance among the five
localities ranges from about 7.5 km to 75 km. Additionally, this species is expected to be found in the Hubei section
of the Three Gorges District, especially in the nearby Badong, Zhushan, and Zhuxi counties (Fig. 1). However, the
total occupancy area of V.pingtaoanum is estimated to be no more than 100 km2 and is projected to decline because
of continuous human activities and global climate changes. Thus, it is assessed as vulnerable (VU: B2 ab (ii, iii))
according to the IUCN criteria.

ZHANG ET AL.
62 • Phytotaxa 564 (1) © 2022 Magnolia Press
FIGURE 2. Holotype of Vincetoxicum pingtaoanum Cai F. Zhang, G.W. Hu & Q.F. Wang (HIB [HIB0208169]). Photographed by Cai-Fei
Zhang.

VINCETOXICUM PINGTAOANUM (APOCYNACEAE) Phytotaxa 564 (1) © 2022 Magnolia Press • 63
FIGURE 3. Vincetoxicum pingtaoanum Cai F. Zhang, G.W. Hu & Q.F. Wang. A–B, habit; C–D, flowering branch; E–F, inflorescence.
A, E, F photographed by Feng Chen from the type locality; B photographed by Hou-Lin Zhou from Fengjie County; C, D photographed
by Hou-Lin Zhou from Wushan County.

ZHANG ET AL.
64 • Phytotaxa 564 (1) © 2022 Magnolia Press
FIGURE 4. Vincetoxicum pingtaoanum Cai F. Zhang, G.W. Hu & Q.F. Wang. A, leaf on lower stem, adaxial (leaf) and abaxial (right)
surfaces; B, leaf on upper stem, adaxial (leaf) and abaxial (right) surfaces; C, flower in back view; D, flower in front view; E, flower in
top view; F, gynostegium in top view; G, gynostegium and corona in side view; H, dissected gynostegium; I, pollinarium; J, compressed
seeds with one surface slightly convex and papillose (left) and the other surface nearly flat (right); K, infructescence. C, D photographed
by Hou-Lin Zhou from Wushan County; A, B photographed by Yan Wang from Hou-Lin Zhou in Cai-Fei Zhang 6512; E–K photographed
by Yan Wang and Cai-Fei Zhang from the type collection.

VINCETOXICUM PINGTAOANUM (APOCYNACEAE) Phytotaxa 564 (1) © 2022 Magnolia Press • 65
Additional specimens examined (Paratypes):—CHINA. Chongqing. Fengjie County, [Xinglong Town], Xinhe,
Guohekou, 700 m, in the humid forest along the roadside, 28 April 1964, Hong-Fu Zhou & He-Yi Su 107855 (IBSC!
[0521747, 0521748]); Wushan County, Guanyang Town, Xinmin Village, 1200 m, on rocks near the bamboo woodland,
20 September 2021, Hou-Lin Zhou in Cai-Fei Zhang 6512 (HIB!).
Observations:—CHINA. Wushan County, Guanyang Town, Xinmin Village, 1200 m, on rocks near the bamboo
woodland photographed by Hou-Lin Zhou in May and August 2020 (Fig. 3: B); Wushan County, Pinghe, 31.275212°N,
110.007323°E, 300 m, in valley, photographed by Hou-Lin Zhou on 11 May 2022; Fengjie County, Xiaozhai, Tiankeng,
600 m, on rocks along the path side, photographed by Hou-Lin Zhou on 16 May 2019 (Fig. 3: C, D; Fig. 4: A, B).
Discussion
Vincetoxicum pingtaoanum is a special species in the genus. Its suffruticose habit with coriaceous and lanceolate leaves
suggests a close relationship to former Biondia species, while all known species of former Biondia have narrower
leaves, always no more than 1 cm wide (vs. mostly more than 1 cm wide), and less developed and minute coronas
(Figs. 4, 5). Our preliminary molecular phylogenetic analyses also showed V. pingtaoanum is closest to the former
Biondia species, e.g., V. henryi (Warb. ex Schlechter in Diels 1900: 542) Liede-Schumann & Meve (2018: 148), V.
insigne (Tsiang 1939: 106) Meve, H.H. Kong & Liede in Liede-Schumann & Meve (2018: 152), V. microcentrum
(Tsiang 1934: 184) Liede-Schumann & Meve (2018: 156), and V. hemsleyanum (Warburg in Schlechter & Warburg
1907: 341) Meve & Liede (2018: 147)] (C-F Zhang et al. unpublished). However, its corona adnate to gynostegium
and not exceeding stamens with lobes moderately swollen are similar to former Tylophora species. As a result, the
hitherto found single old collection of V. pingtaoanum, Hong-Fu Zhou & He-Yi Su 107855 (IBSC [0521747, 0521748]),
had been misidentified as Tylophora hui Tsiang (1936: 236) [≡ V. hui (Tsiang) Meve & Liede (2018: 150)], which is
only known with few collections from southern Yunnan Province and a single collection from Guizhou Province. V.
pingtaoanum is significantly different from V. hui based on the glabrous stems (vs. trichomes along one side on stems),
much shorter leaf blades ( 2.2–7 cm vs. 6.5–15 cm), and petioles (0.5–1 cm vs. 1.5–2.5 cm), yellowish green and
adaxially puberulent (vs. greenish and glabrous) corollas with ca. 5 mm long narrowly lanceolate (vs. ca. 3 mm long
ovate) lobes as well as different coronas and pollinaria. Recent phylogenetic studies revealed the non-monophyly of
former genera Biondia and Tylophora within the large Vincetoxicum s.l. clade (Liede-Schumann et al. 2012, 2016). V.
pingtaoanum is a good example that shows the artificiality of the previous morphological classifications of Biondia
and Tylophora.
V. pingtaoanum is also similar to V. emeiense S.Y. Zeng & Q.Y. Yang in Zeng et al. (2021: 59) based on corolla
shapes and sizes (Figure 4). The latter is a recently described new species from Mt. Emei, Sichuan Province (Zeng et
al. 2021), but differs by differently coloured corollas, shorter inflorescences, different coronas, and pollinaria (Table
1, Fig. 5). Detailed morphological comparisons among V. pingtaoanum, V. emeiense, V. henryi, V. insigne and V.
microcentrum are presented in Table 1.
Three Gorges District is one of the diversity centers for Chinese Vincetoxicum. 24 species of Vincetoxicum are
hitherto known from this district, including 12 species previously placed in the Cynanchum sect. Vincetoxicum, five
species in former Biondia, five species in former Tylophora, one species in former Belostemma (Tsiang and Li 1977;
Liang 1994; Peng 2005; Li et al. 1995) and V. pingtaoanum reported herein. A key to all known species of Vincetoxicum
from the Three Gorges District is provided to facilitate field and herbarium identifications as well as finding potential
new species or newly recorded species from this district.
TABLE 1. Morphological comparison of Vincetoxicum pingtaoanum, V. emeiense, V. henryi and V. microcentrum.
V. pingtaoanum V. emeiense V. henryi V. insigne V. microcentrum
Stem glabrous glabrous glabrous, sparsely
puberulent when young
puberulent along one
side
puberulent along one or
two sides
Petiole 0.5–1 cm 1–2 cm 2–3 mm ca. 1 cm 0.5–1.0 cm
Leaf blade:
Trichomes only on main
vein
only on margins only on main vein when
young
only on main vein only on main vein and
margins
Main lateral veins obviously 4–5
pairs
obviously 4–5
pairs
obscurely 2–3 pairs obviously 2–3 pairs obscurely 4–7 pairs
Size 2.2–8 × 0.8–3 cm 6–10 × 2–3.5 cm 3–8 × 0.5–1.2 (-2) cm 3–7 × 0.3–1.5 cm 1–7 × 0.5–1.4(– 2.3) cm
...continued on the next page

ZHANG ET AL.
66 • Phytotaxa 564 (1) © 2022 Magnolia Press
TABLE 1. (Continued)
V. pingtaoanum V. emeiense V. henryi V. insigne V. microcentrum
Inflorescence rachis not
branched,
2.5–6 cm, mostly
longer than
leaves
rachis branched,
7–11 cm, longer
than leaves
umbel-like (without
rachis),
1–2 cm, shorter than
leaves
umbel-like (without
rachis),
1.5–5 cm, shorter
than leaves
umbel-like (without
rachis), 1–2 cm, much
shorter than leaves
Corolla colour yellowish green yellowish brown purplish red yellowish green lobes purplish red, tubes
white
Corolla shape rotate rotate campanulate campanulate urceolate
Corolla lobes linear-lanceolate,
ca. 5 mm long
linear-
lanceolate, 5–5.5
mm long
ovate-triangular, ca. 1.7
mm long
ovate-oblong, ca. 1.7
mm long
oblong-lanceolate or
oblong-elliptic, 1–2 mm
long
Corona inserted
above the half
gynostegium,
lobes obtuse
(Fig. 6: A)
inserted
near base of
gynostegium,
lobes truncate
(Fig. 6: B)
inserted near base of
gynostegium, lobes
acute (Fig. 6: C)
ringlike, rim
shallowly 5-cleft
(Fig. 6: D
minute, ring-like (Fig.
6: E)
Caudicle horizontal straightly
ascending
inflexed ascending horizontal suberect
Pollinia pendulous pendulous pendulous pendulous suberect
FIGURE 5. Similar species Vincetoxicum henryi (A–C), V. insigne (D–F), and V. microcentrum (G–I). A, D, G, flowering plant; B, E, H,
inflorescence; C, F, I, flower in top view; A, B photographed by Hou-Lin Zhou from Wushan County; C photographed by Cai-Fei Zhang
from Hou-Lin Zhou in Cai-Fei Zhang 6531 (HIB); D–F photographed by Rui Tang from Daocheng County, Sichuan Province, China; G–I
photographed by Cai-Fei Zhang and based on Miao Liao ZJLM02 (HIB).

VINCETOXICUM PINGTAOANUM (APOCYNACEAE) Phytotaxa 564 (1) © 2022 Magnolia Press • 67
FIGURE 6. Comparison of coronas (arrows) among Vincetoxicum pingtaoanum (A), V. emeiense (B), V. henryi (C), V. insigne (D) and
V. microcentrum (E). A photographed by Yan Wang from the type collection; B provided by Si-Yuan Zeng from the type collection; C
photographed by Cai-Fei Zhang from Hou-Lin Zhou in Cai-Fei Zhang 6531 (HIB); D from Tsiang (1941: fig. 12); E photographed by
Cai-Fei Zhang from Miao Liao ZJLM02 (HIB).
Key to the species of Vincetoxicum from the Three Gorges District in Central China:
1. Shrubs or herbs; stems climbing or prostate .......................................................................................................................................2
- Herbs, rarely subshrubs; stems erect, sometimes uppermost parts twining .....................................................................................16
2. Leaf blades mostly lanceolate to linear, less than 2 cm wide; petioles no more than 1 cm long .......................................................3
- Leaf blades ovate, elliptic, or ovate-oblong, more than 2 cm wide; petioles more than 1 cm long .................................................11
3. Stems puberulent along 1 or 2 lines; peduncles less than 1 cm long, or up to 3 cm (V. pilosellum) ..................................................4
- Stems glabrous, or sparsely puberulent but not along lines; peduncles more than 2 cm long ...........................................................6
4. Peduncles up to 3 cm long ...............................................................................................................................................V. pilosellum
- Peduncles 5–8 mm long ......................................................................................................................................................................5
5. Corollas urceolate, with white tubes and purplish red lobes ..................................................................................... V. microcentrum
- Corollas campanulate, yellow ...................................................................................................................................... V. shaanxiense
6. Corollas purplish red ..........................................................................................................................................................................7
- Corollas yellow, yellowish green or white .........................................................................................................................................8
7. Leaf lateral veins obvious, ca. 4 pairs; corollas internally glabrous ...................................................................................V. silvestre
- Leaf lateral veins obscure; corollas internally puberulent ......................................................................................................V. henryi
8. Leaves mostly more than 1 cm wide; coronas less developed, lobes ringlike, inserted near base of gynostegium ...........................9
- Leaves mostly less than 1 cm wide; coronas well developed, lobes ovoid, reaching anther base ...................................................10
9. Corollas white, lobes much shorter than tubes ........................................................................................................... V. hemsleyanum
- Corollas yellowish green, lobes much longer than tubes ............................................................................................V. pingtaoanum
10. Stems glabrous; leaf blades linear-lanceolate, 5.5–9 cm long; corollas green or yellow ........................................................ V. kerrii
- Stems puberulent along 1 line; leaf blades oblong-ovate, 3–5 cm long; corollas purplish red .................................... V. floribundum
11. Stems and leaves densely hirsute or puberulent ...............................................................................................................................12
- Stems glabrous or puberulent along 1 line; leaves glabrous or only puberulent on midveins .........................................................13
12. Stems and leaves densely hirsute; corollas dark purplish red; corona lobes horned-falcate, horizontally stellate spreading (former
Belostemma) ..................................................................................................................................................................V. belostemma
- Stems and leaves densely puberulent; corollas purple, or yellow with somewhat purple; corona lobes only slightly swollen, not
spreading .............................................................................................................................................................................V. chinense
13. Evergreen woody lianas; leaf blades thinly coriaceous, not cordate at base, no more than 8 × 3 cm .........................V. pingtaoanum
- Deciduous herbs; leaf blades chartaceous to membranous, usually cordate or shallowly cordate at base, if rounded then mostly
larger than 8 × 3 cm (V. henryanum) ................................................................................................................................................14
14. Peduncles usually shorter than pedicels; rachis always short, unbranched ....................................................................V. henryanum
- Peduncles usually longer than pedicles; rachis often many branched ..............................................................................................15
15. Leaf blades oblong-ovate to hastate, base cordate to rounded; petioles less than 1.5 cm long; corollas purple, 2–3 mm in diameter
......................................................................................................................................................................................V. floribundum
- Leaf blades ovate or ovate-oblong, base cordate to cuneate or truncate; petioles 1.5 cm or longer; corollas greenish or greenish
orange, 4–6 mm in diameter ..................................................................................................................................... V. augustinianum
16. Upper stems twining; inflorescences extra-axillary .........................................................................................................................17
- Erect herbs; inflorescences terminal or nearly terminal ...................................................................................................................18
17. Leaves no more than 10 cm long ......................................................................................................................................V. versicolor
- Leaves more than 10 cm long except upper smaller ones .......................................................................................... V. chekiangense
18. Leaf blades ovate, elliptic, or ovate-oblong, less than 3 times as long as wide ...............................................................................19
- Leaf blades linear or narrowly lanceolate, 4 or more times as long as wide ....................................................................................21
19. Stems densely tomentose; leaves densely tomentose on both surfaces; inflorescences mostly sessile; corollas dark purplish red ....
.............................................................................................................................................................................................V. atratum
- Stems pubescent along 1 side; leaves puberulent only on veins; inflorescences pedunculate .........................................................20
20. Corollas yellow to brownish or purple, interior puberulent or puberulent except sometimes for lobes .............................V. forrestii
- Corollas yellow, interior glabrous except sometimes for a few trichomes inside tube ................................................. V. inamoenum

ZHANG ET AL.
68 • Phytotaxa 564 (1) © 2022 Magnolia Press
21. Stems puberulent along 1 or 2 lines .................................................................................................................................................22
- Stems glabrous ..................................................................................................................................................................................25
22. Stems puberulent along 2 lines ..................................................................................................................................... V. glaucescens
- Stems puberulent along 1 line, at least on young branches ..............................................................................................................23
23. Leaves 3–6 in a whorl, at least in lower stem; corollas white ..................................................................................... V. verticillatum
- Leaves opposite; corollas purplish red or yellow .............................................................................................................................24
24. Leaf blades ovate-lanceolate, 3–10 × 1–3 cm; corollas purplish red ...........................................................................V. mongolicum
- Leaf blades linear-lanceolate, ca. 6 × 0. 5 cm; corollas yellow .................................................................................. V. stenophyllum
25. Leaf blades no more than 5 mm wide; petioles ca. 5 mm long; corollas purpulish red; in wet places ............................ V. stauntonii
- Leaf blades mostly more than 5 mm wide; petioles less than 5 mm long; corollas yellowish green; in dry places .... V. mukdenense
Acknowledgements
We thank Prof. Ping-Tao Li for checking the new species and his discussions and suggestions. We express our
gratitude to the curators and staff of the following herbaria for their kind permissions to CANT, CDBI, E, EMA, HIB,
HHBG, HZU, IBSC, KUN, NAS, PE, SM, SZ, and ZM. We are grateful to Dr. Si-Yuan Zeng (Southwest University,
Chongqing) and Rui Tang for providing photos of Vincetoxicum emeiense and V. insigne, respectively, and to Drs.
Cheng Du (Chenshan Botanical Garden, Shanghai), Yi-Hua Tong (South China Botanical Garden, CAS) and Shuai
Liao (East China Normal University) for providing some literature to us. We also thank Sigrid Liede-Schumann,
Michele Rodda and anonymous reviewers for their reviews. This study was supported by the Management Service
Center of Chongqing Yintiaoling National Nature Reserve and was funded by the Biological Resources Program,
Chinese Academy of Sciences (KFJ-BRP-017-10), and a project from China National Plant Specimen Resource Center
to the first author (E0117G1001).
References
Brown, R. (1810) Prodromus Florae Novae Hollandiae et Insulae van-Diemen: Exhibens Characteres Plantarum Quas Annis 1802-1805.
R. Taylor et socii, Londini, 590 pp.
https://doi.org/10.5962/bhl.title.52309
Chun, W.Y. & Tsiang, Y. (1941) Merrilanthus, a new genus of Asclepiadacae from Hainan. Sunyatsenia 6: 105–108, pl. 17–18.
Civeyrel, L., Le Thomas, A., Ferguson, K. & Chase, M.W. (1998) Critical reexamination of palynological characters used to delimit
Asclepiadaceae in comparison to the molecular phylogeny obtained from plastid matK sequences. Molecular Phylogenetics and
Evolution 9: 517–527.
https://doi.org/10.1006/mpev.1997.0510
Diels, L. (1900) Die Flora von Central-China. Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 29
(3–4): 169–659.
Diels, L. (1905) Beiträge zur Flora des Tsin ling shan und andere Zusätze zur Flora von Central-China. Botanische Jahrbücher für
Systematik, Pflanzengeschichte und Pflanzengeographie 36 (5; Beibl. 82): 1–138.
Endress, M., Meve, U., Middleton, D. & Liede-Schumann, S. (2018) Apocynaceae, In: Kadereit, J.W. & Bittrich, V. (eds.) Families and
Genera of Vascular Plants, vol. XV. Springer, Berlin, pp. 207–411.
https://doi.org/10.1007/978-3-319-93605-5_3
ESRI (2013) ArcGIS Desktop Release 10.2. Environmental Systems Research Institute, Redlands, California, USA.
Hsu, T.C., Huang, W.J. & Chung, S.W. (2021) Vincetoxicum (Apocynaceae: Asclepiadoideae) in Taiwan: Two new combinations and a
new record. Phytotaxa 478: 287–290.
https://www.doi.org/10.11646/phytotaxa.478.2.11
Idrees, M. & Hsu, T.C. (2021) Validation of the name Vincetoxicum taiwanense (Apocynaceae). Phytotaxa 518: 177–178.
https://doi.org/10.11646/phytotaxa.518.2.7
IUCN (2017) Guidelines for Using the IUCN Red List Categories and Criteria. Version 13. Prepared by the Standards and Petitions
Subcommittee. [http://www.iucnredlist.org/documents/RedListGuidelines.pdf]
Jiang, L.Q., Li, Y.Y., Zhu, X.X., Wang, Y. & Peng, H. (2018) Vincetoxicum xinpingense (Asclepiadeae, Asclepiadoideae, Apocynaceae), a
new species from Yunnan Province, China. Phytotaxa 361: 56–64.
https://doi.org/10.11646/phytotaxa.361.1.4
Kidyoo, A & Kidyoo, M. (2018) A new species of Hoya (Marsdenieae), three new combinations and two new names in Vincetoxicum

VINCETOXICUM PINGTAOANUM (APOCYNACEAE) Phytotaxa 564 (1) © 2022 Magnolia Press • 69
(Asclepiadeae) from Thailand. Taiwania 63: 25–31.
https://doi.org/10.6165/tai.2018.63.25
Li, P.T., Gilbert, M.G. & Steven, W.D. (1995) Asclepiadaceae. In: Wu, Z.Y. & Raven, P.H. (eds.) Flora of China, vol. 16. Science Press &
Missouri Botanical Garden, Beijing & St. Louis, pp. 189–270.
Liang, S.Y. (1994) Plant checklist of the Three Gorges Reservoir Area. In: Chen, W.L., Zhang, X.Q., Liang, S.Y., Jin, Y.X. & Yang, Q.X.
(eds.) Plants and Compound Agroecosystem in the Three Gorges Reservoir Area. Science Press, Beijing, pp. 49–263. [In Chinese]
Liede, S. (1996) Cynanchum - Rhodostegiella - Vincetoxicum - Tylophora (Asclepiadaceae): New considerations on an old problem. Taxon
45: 193–211.
https://doi.org/10.2307/1224660
Liede, S. (2001) Subtribe Astephaninae (Apocynaceae - Asclepiadoideae) reconsidered: new evidence based on cpDNA spacers. Annals
of the Missouri Botanical Garden 88: 657–668.
https://doi.org/10.2307/3298638
Liede, S., Täuber, A. & Schneidt, J. (2002) Molecular considerations in the Tylophorinae K. Schum. (Apocynaceae - Asclepiadoideae).
Edinbourgh Journal of Botany 59: 377–403.
http://doi.org/10.1017/S0960428602000239
Liede-Schumann, S., Khanum, R., Mumtaz, A.S., Gherghel, I. & Pahlevani, A. (2016) Going west–A subtropical lineage (Vincetoxicum,
Apocynaceae: Asclepiadoideae) expanding into Europe. Molecular Phylogenetics and Evolution 94: 436–446.
http://dx.doi.org/10.1016/j.ympev.2015.09.021
Liede-Schumann, S., Kong, H., Meve, U. & Thiv, M. (2012) Vincetoxicum and Tylophora (Apocynaceae: Asclepiadoideae: Asclepiadeae)—
two sides of the same medal: Independent shifts from tropical to temperate habitats. Taxon 61: 803–825.
http://doi.org/10.1002/tax.614007
Liede-Schumann, S. & Meve, U. (2018) Vincetoxicum (Apocynaceae - Asclepiadoideae) expanded to include Tylophora and allies.
Phytotaxa 369: 129–184.
https://doi.org/10.11646/phytotaxa.369.3.1
Linnaeus, C. (1753) Species Plantarum. Impensis Laurentii Salvii, Holmiae [Stockholem], 1200 + xxxi pp.
https://doi.org/10.5962/bhl.title.669.
Peng, Z.H. (2005) Encyclopedia of Plants in Three Gorges of Yangtze River of China. Science Press, Beijing, 1771 pp. [In Chinese]
Qiu, S.X., Li, D.Z., Zhang, Z.X., Zhou, J. & Wu, Z.Y. (C.Y.) (1989) Chemotaonomy of Cynanchum and its allied genera with notes on
the generic characteristics of Vincetoxicum. Acta Botanica Yunnanica 11: 41–50. [In Chinese; https://journal.kib.ac.cn/EN/Y1989/
V11/I01/1]
Sennblad, B. & Bremer, B. (2000) Is there a justification for differential a priori weighting in coding sequences? A case study from rbcL
and Apocynaceae s.l. Systematic Biology 49: 101–113.
Schlechter, R. & Warburg, O. (1907) Asclepiadaceae novae Asiae australis et orientalis. II. Repertorium Specierum Novarum Regni
Vegetabilis 3: 339–347.
https://doi.org/10.1002/fedr.19070034803
Shah, S.A., Sultan, A. Wen, J., Ullah, Z., Nisa, S.U., Ren, Z., Alam, M.M., Iqbal, J. & Mumtaz, A.S. (2021) Taxonomy of Vincetoxicum
s. str. (Asclepiadoideae, Apocynaceae) from southern Asia including three new species and resurrected names. PhytoKeys 179:
35–73.
https://doi.org/10.3897/phytokeys.179.62514
Thiers, B. (2021) [continuously updated] Index Herbariorum: A global directory of public herbaria and associated staff. New York
Botanical Garden’s Virtual Herbarium. Available from: http://sweetgum.nybg.org/ih/ (accessed 10 August 2021)
Tseng, Y.H., Chao, C.T. & Lin, H.W. (2011) A new species of Tylophora from coral reef areas in Hengchun Peninsula, Taiwan, China.
Journal of Systematics and Evolution 49: 162–162.
https://www.doi.org/10.1111/j.1759-6831.2011.00121_3.x
Tsiang, Y. (1934) Notes on the Asian Apocynales 2. Sunyatsenia 2: 89–202, pl. 1–35.
Tsiang, Y. (1936) Notes on the Asian Apocynales III. Sunyatsenia 3: 121–239.
Tsiang, Y. (1939) An enumeration of the asclepiadaceous plants collected by Tsai and Wang from Yunnan in 1933–1936. Sunyatsenia 4:
95–131.
Tsiang, Y. (1941) Notes on the Asian Apocynales V. Sunyatsenia 6: 109–158.
Tsiang, Y. & Li, P.T. (1974a) Praecursores Florae Asclepiadacearum Sinensium. Acta Phytotaxonomica Sinica 12 (1): 79–149. [In Chinese;
https://www.jse.ac.cn/EN/Y1974/V12/I1/79]
Tsiang, Y. & Li, P.T. (1974b) Apocynaceae, Periplocaceae, and Asclepiadacae. In: Anonymous (ed.) Flora Hainanica, vol. 3. Science
Press, Beijing, pp. 218–285, 577–578. [In Chinese]
Tsiang, Y. & Li, P.T. (1977) Apocynaceae and Asclepiadaceae. Flora Reipublicae Popularis Sinicae, vol. 63. Science Press, Beijing, 617

ZHANG ET AL.
70 • Phytotaxa 564 (1) © 2022 Magnolia Press
pp. [In Chinese]
Wight, R. (1834) Contributions to the botany of India. Parbury, Allen, & Co., London, 136 pp.
Wolf, N.M. von (1776). Genera Plantarum vocabulis characteristicis definita. Müller, Danzig, 185 pp.
Yamashiro, T., Fukuda, T., Yokoyama, J. & Maki, M. (2004) Molecular phylogeny of Vincetoxicum (Apocynaceae-Asclepiadoideae) based
on the nucleotide sequences of cpDNA and nrDNA. Molecular Phylogenetics and Evolution 31: 689–700.
https://doi.org/10.1016/j.ympev.2003.08.016
Ye, B.J., Tu, X.D., Zhou, C.Y., Liu, B., Cao, X.F. & Chen, S.P. (2022) Vincetoxicum junzifengense (Apocynaceae), a new species from
Fujian, China: Evidence from morphological and molecular analyses. Phytotaxa 539 (2): 203–209.
https://doi.org/10.11646/phytotaxa.539.2.7
Ying, T.S. (1996) Areography of the endemic genera of seed plants in China. Acta Phytotaxa Sinica 34 (5): 479–485. [In Chinese; https://
www.jse.ac.cn/EN/Y1996/V34/I5/479]
Ying, T.S. (2001) Species diveristy and distribution pattern of seed plants in China. Biodiversity Science 9 (4): 393–398. [In Chinese]
https://www.doi.org/10.17520/biods.2001058
Zeng, S.Y., Yang, Q.Y., Yu, J. & Shen, J.Y. (2021) Vincetoxicum emeiense (Asclepiadeae, Asclepiadoideae, Apocynaceae), a new species
from Sichuan, China. Phytotaxa 505: 56–62.
https://www.doi.org/10.11646/PHYTOTAXA.505.1.3
Zheng, Z. (1994) The endemism of Chinese seed plants in Three Gorge reservoir area, Changjiang River, China. Journal of Wuhan
Botanical Research 12: 341–347. [In Chinese; http://www.whzwxyj.cn/CN/Y1994/V12/I4/341]