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Aristolochia pulvinata, a new species of Aristolochiaceae from Yunnan, Southwest China

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Aristolochia pulvinata Yi-Fan Wang & Zhi-Jian Yin, a new species of Aristolochia subgenus Siphisia (Aristolochiaceae) from Yunnan Province, southwest China, is described and illustrated. Aristolochia pulvinata is distinguished by its unique characters: an elevated and thickened pulvinate structure in the inferior calyx limbs of its perianth. Morphologically, it resembles A. ovatifolia, A. melanocephala, A. utriformis, and A. luudamcui due to the similar thickening on the calyx limb region, but it differs in terms of degree, surface texture, color, and angle, as well as leaf morphology. This species, discovered and known only from one region, is assessed as Critically Endangered (CR) according to IUCN categories and criteria. This publication includes detailed morphological illustrations of A. pulvinata, with comparative photo plates and a table that highlights distinguishing features relative to similar species.
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Phytotaxa 675 (3): 261–272
https://www.mapress.com/pt/
Copyright © 2024 Magnolia Press Article PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Accepted by Marie-Stéphanie Samain: 22 Nov. 2024; published: 4 Dec. 2024
https://doi.org/10.11646/phytotaxa.675.3.5
261
Aristolochia pulvinata, a new species of Aristolochiaceae from Yunnan, Southwest
China
HONG-LIN ZHANG1, 5, YI-FAN WANG2, 6, ZI-RUI GUO3, 7, TONG ZHU1, 8, HU-HUA YANG4, 9 & ZHI-JIAN
YIN1, 10, *
1Southwest Survey and Planning Institute of National Forestry and Grassland Administration, Kunming 650031, Yunnan, China
2Department of Environmental Studies, New York University, New York 10012, USA
3Suzhou Lianhelvyou Ecological Agriculture Development Co., LTD, Suzhou 215026, Jiangsu, China
4Management Bureau of Jinguangsi Provincial Nature Reserve, Dali 672699, Yunnan, China
5
2410942152@qq.com; https://orcid.org/0009-0008-2078-4240
6
yw7200@nyu.edu; https://orcid.org/0009-0003-1339-1856
7
kevinkuwk0714@gmail.com; https://orcid.org/0009-0004-1817-9827
8
2817436850@qq.com; https://orcid.org/0009-0005-9379-0527
9
414178944@qq.com; https://orcid.org/0009-0001-8680-125X
10
592363239@qq.com; https://orcid.org/0000-0002-9791-5869
*Author for correspondence
Abstract
Aristolochia pulvinata Yi-Fan Wang & Zhi-Jian Yin, a new species of Aristolochia subgenus Siphisia (Aristolochiaceae)
from Yunnan Province, southwest China, is described and illustrated. Aristolochia pulvinata is distinguished by its unique
characters: an elevated and thickened pulvinate structure in the inferior calyx limbs of its perianth. Morphologically, it
resembles A. ovatifolia, A. melanocephala, A. utriformis, and A. luudamcui due to the similar thickening on the calyx limb
region, but it differs in terms of degree, surface texture, color, and angle, as well as leaf morphology. This species, discovered
and known only from one region, is assessed as Critically Endangered (CR) according to IUCN categories and criteria. This
publication includes detailed morphological illustrations of A. pulvinata, with comparative photo plates and a table that
highlights distinguishing features relative to similar species.
Key words: Aristolochia, conservation, new species, perianth, subgenus Siphisia
Introduction
The genus Aristolochia Linnaeus (1753: 960) is the largest in the family Aristolochiaceae, comprising about 600 species
widely distributed across tropical, subtropical, and temperate regions (Huber 1993; Neinhuis et al. 2005; Wanke et
al. 2006). Due to its remarkable species diversity, unique floral morphology, and complex ecological interactions
with pollinators and parasitic insects (Rulik et al. 2008; Zhang et al. 2019; Allio et al. 2021; Alpuente et al. 2023),
Aristolochia has been a focal point for botanical and ecological research, leading to numerous recent discoveries. The
taxonomic, nomenclatural and systematic studies of this genus have garnered significant scholarly attention (González
1999b; Wanke et al. 2006; Ohi-Toma & Murata 2016; Zhu et al. 2019a).
Phylogenetic studies combined with morphological evidence indicate that Aristolochia sensu lato consists of three
monophyletic subgenera: Aristolochia Schmidt (1935: 237), Siphisia Duchartre (1854: 29) Schmidt (1935: 236) and
Pararistolochia Hutchinson & Dalziel (1927: 75) Schmidt (1935: 241) (Ma 1989, González & Stevenson 2002; Wanke
et al. 2006; Buchwalder et al. 2014; Ohi-Toma & Murata 2016). The monophyly of these clades is well-established
and widely accepted within the scientific community (Ohi-Toma et al. 2006; Wanke et al. 2006; Buchwalder et al.
2014; Ohi-Toma & Murata 2016). However, there has been ongoing debate about the taxonomic treatment of subgenus
Siphisia. Some researchers propose reinstating Siphisia to the genus level under the name Isotrema Rafinesque (1819:
195), based on molecular evidence from both plastid genic spacers and nuclear genes (Zhu et al. 2019a). While this
reclassification has been adopted by some scholars who have described new species under the Isotrema framework
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262 Phytotaxa 675 (3) © 2024 Magnolia Press
(Li et al. 2019; Cai et al. 2020; Lu et al. 2022; Huang et al. 2022; Ma et al. 2023; Xu et al. 2023), the majority of the
botanical community continues to follow the Aristolochia sensu lato framework. These dual frameworks reflect the
current and ongoing taxonomic debate within the field. For the purposes of this study, we acknowledge the parallel
taxonomic frameworks but choose to follow the widely recognized Aristolochia subgenus Siphisia classification. This
approach aligns with longstanding botanical tradition and enhances clarity for the scientific community.
The subgenus Siphisia currently includes at least 127 valid taxa: 125 species, one subspecies, and one variety
(Ma et al. 2023; Xu et al. 2023; Zhu et al. 2017; Zhu & Ma 2022). These species are primarily distributed in East
and South Asia, with some extending into North and Central America (Pfeifer 1966; González 1999a; Huang et al.
2003; Ohi-Toma et al. 2006; Wanke et al. 2006; González et al. 2014). Morphologically, Siphisia is distinguished by
features such as a strongly curved perianth, a three-lobed gynostemium, and anthers paired on the outer surface of each
gynostemium segment (González & Stevenson 2000a; b). The members of this subgenus often exhibit high levels of
endemism, occupying narrow ecological niches and forming small, localized populations (Luo et al. 2020; Huang et
al. 2022; Xu et al. 2023). Due to their often-cryptic flowering patterns, such as cauliflory or predominantly vegetative
growth, many species remain difficult to notice or identify without the presence of flowers, leading to taxonomic errors
and ongoing revisions, such as the case of A. austroyunnanensis Huang (1981) (Zhu et al. 2017) and A. utriformis
Huang (1981) (Zhu et al. 2019b; Phan et al. 2021). Consequently, there is still much to discover within this subgenus,
and many new species continue to be described as aforementioned.
During a botanical field expedition to the Jinguangsi Nature Reserve, Yongping County, Yunnan, Southwest China,
in March and April 2024, we encountered a climbing, shrubby Siphisia forming a small population in bloom that may
represent an undescribed species. This potential species is distinguished by a pronounced thickening in the adaxial
side of the inferior calyx limb's area. Comparative analyses of literature and voucher specimens, along with dissections
of living material of flowers, indicate that while similar morphological traits occur in species like A. luudamcui from
North Vietnam (Phan et al. 2021), A. ovatifolia from Southwest China (Huang 1985), and A. melanocephala from
East Yunnan (Zhu et al. 2018), the degree and positioning of the calyx limb thickening in the Yongping population are
unique and previously unobserved.
In further fieldwork conducted in late April 2024 in the Jinguangsi Nature Reserve, we observed populations
consistently displaying a distinct elevated calyx limb morphology across several individuals, indicating that this
trait may belong to a previously unrecognized Aristolochia species. Aristolochia ovatifolia was also found growing
sympatrically in the same habitats, with both species flowering synchronously. Morphological comparisons of A.
ovatifolia specimens from the region confirmed their consistency with Huang's (1981) type descriptions. Despite
certain morphological similarities between A. ovatifolia and the newly observed Aristolochia, their close proximity and
overlapping flowering periods raised the possibility of potential gene flow. We paid special attention to investigating
signs of such interaction, but no individuals with intermediate traits were detected, suggesting reproductive isolation
between the two species. These findings point to the presence of a previously undescribed species, warranting its
formal taxonomic description and illustration. While the possibility of hybridization due to the overlapping distribution
of the two species was considered, no evidence supporting such interaction was observed. The new species, although
found alongside A. ovatifolia, remains distinct in both morphology and reproduction, confirming its unique taxonomic
status.
Materials & methods
The specimens under study were collected in the Jinguangsi Nature Reserve, Yongping County, Dali Bai Autonomous
Prefecture, Yunnan Province, China, and deposited in the Herbarium of the Kunming Institute of Botany (KUN),
Chinese Academy of Sciences. Morphological features such as flower shape, color, and longitudinal sections of floral
organs were compared with original descriptions and voucher specimens available at various herbaria: HITBC, IBSC,
KUN, GZTM, SM, CSH, PEM, A, NY. The species description follows methods and terminologies set forth by Pfeifer
(1966), Huang et al. (2003) and Zhu et al. (2019a). The conservation status assessment was based on existing literature
regarding its ecological role in local ecosystems, field data, and the criteria of the IUCN (2024).
A NEW SPECIES OF ARISTOLOCHIA FROM CHINA Phytotaxa 675 (3) © 2024 Magnolia Press 263
Results
Taxonomic treatment
Aristolochia pulvinata Yi-Fan Wang & Zhi-Jian Yin, sp. nov.
Figures 1–2
Type:—CHINA. Yunnan province, Dali Bai autonomous prefecture, Yongping county, Shanyang town, Jinguangsi nature reserve, 25°11´N,
99°32´E, 2446 m, 10 April 2024, flowering, H. L. Zhang & T. Zhu JGS654 (holotype KUN1601585!; isotypes KUN1601586!,
KUN1601587!).
Diagnosis:—Aristolochia pulvinata is distinguished by a prominent elliptical, elevated thickened region on the adaxial side of the calyx
limb, encircling the throat, with the three dentate lobes connate, forming a triangular perianth opening. The limb’s interior surface is
densely covered with dark purple granular pustules. Morphologically, it is most similar to the sympatrically distributed Aristolochia
ovatifolia, but can be readily distinguished by the absence of such an elevated thickening on A. ovatifolia's calyx limb, which instead
features a smooth, velvet-textured interior surface. In leaf morphology, A. ovatifolia has ovate, thick, felted leaves with long, rusty
villi on both sides, whereas A. pulvinata presents cordate leaves with an acuminate apex, sparsely covered with short indumentum.
Description:—Climbing shrub, 0.5–1.8 m Roots cylindrical, young roots capable of forming creeping roots; older
roots lignified, diameter 0.8–3.0 cm, cross-section circular to elliptical, xylem yellow, with xylem rays grouped into
three equal clusters. Stems cylindrical; young branches densely covered with rusty short indumentum, older branches
glabrous to scabrous; transition from green, herbaceous young branches to older branches with a coarse, barley-
like texture on the surface; fully lignified stems develop a surface forming rough, warty bark. Petioles 3.0-6.0 cm
long; juvenile leaves densely rusty villous; mature leaves adaxially sparsely tomentose to appressed, abaxially slightly
pubescent, showing palmate venation, with two pairs of veins symmetrically extending laterally from the base of the
central midrib; leaf blades lanceolate, bases cordate, margins entire, 6.0-15.0 × 3.0-8.0 cm, papery; sinuses deep, 0.5-
1.5 cm; apices acute. Flowers often solitary or in pairs, axillary on young branches, and cauliflorous on lignified stems,
typically emerging from nodular structures formed by meristematic tissue in the axils of previously fallen leaves.
On lignified stems, fascicles commonly bear 2–4 flowers on average.; pedicels 1.0-2.0 cm long, usually pendant,
densely covered with rusty short indumentum. Perianth abaxially scabrous with a short yellow to brown indumentum;
bracteoles reduced or very small, triangular, attached at the base of the pedicel, both surfaces densely covered with
rusty woolly villous, sessile. Calyx fused into a geniculated, tuberous perianth, zygomorphic; utricle extending from
the calyx-pedicel junction downward about 0.8-1.0 cm; calyx tube geniculately curved; utricle from the pedicel-joint
downward 0.6-1.2 cm, cylindric, abaxially green-yellowish with sparse pubescence, adaxially dark purplish, arachnoid
villous; from utricle to geniculation 1.0-1.4 cm, abaxially yellowish to purplish, sparsely tomentose; adaxially purplish,
glabrous, with a velvety texture, ridged with veins; from geniculation to the calyx throat, 1.2-1.8 cm, abaxially
purplish, sparsely tomentose; abaxially purple to reddish, glabrous, velvety, smooth, gourd-shaped tube; near the
throat region darkening to black purple for 0.2-0.3 cm. Calyx limb trilobate, semi-open saccate, 0.9-1.5 cm long, 1.0-
1.2 cm in diameter, abaxially purplish red to yellowish green; adaxially densely covered with dark purple granular
pustules. Upon floral anthesis, downward lobe reflexes, curling back to create a triangular aperture at the calyx limb's
opening., throat ca. 0.1–0.2 cm in diameter, from throat opening to the margin of the inferior lobe, quickly elevating
and thickening, forming a pulvinate structure from 0.1-0.2 cm above the throat extending downward to the lower lobe
edge, the entire thickening region oval, thickest in the middle, edges thin, thickness up to 0.3-0.5 cm, edges sparsely
covered with some purple pustules, central part of pulvinate smooth, waxy, occasionally with brown dots, obliquely
outward at approximately 70 degrees relative to the horizontal, function pending further investigation. Stamens 6, in
one series, fully adnate with the style column to form a gynostemium, in three pairs opposite stigma lobes; filaments
absent; anthers oblong, approximately 0.1-0.2 cm long, extrorse. Gynostemium approximately 0.3 cm long, diameter
0.18-0.25 cm, fleshy; lobes 3, apex obtuse; margin crisped; ovary inferior, cylindrical, 0.5-0.7 cm long, diameter 0.2-
0.4 cm, with 6 ridges, densely rusty villous abaxially. Capsule and seeds not observed.
Distribution and habitat:—Aristolochia pulvinata is currently documented solely at its type location, thriving in
moist, shaded habitats along montane stream banks. The microhabitat is primarily characterized by a dark brown humic
layer, occasionally found amid streamside debris. The forest, achieving a canopy closure of 70–80%, predominantly
consists of Castanopsis orthacantha Franchet (1899: 194) (Fagaceae) and Camellia reticulata Lindley (1827: 1078)
(Theaceae), among other species. The understory is prevalently occupied by Sarcococca wallichii Stapf (1916: 37)
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264 Phytotaxa 675 (3) © 2024 Magnolia Press
(Buxaceae) and Sarcococca hookeriana var. digyna Franchet (1889: 135) (Buxaceae). The estimated population of this
species is currently around 100 individuals, distributed from an altitude of 2435 m to 2656 m above sea level.
Phenology:—Flowering from March to May. Fruit or seed not observed.
FIGURE 1. Aristolochia pulvinata Yi-Fan Wang & Zhi-Jian Yin. sp. nov. A. Habitat, B. Habit in situ, C. Frontal abaxial view of the bud,
D. A pair of flowers in a fascicle on lignified stem, E. Front view of the flower, F–G. Longitudinal section of the flower, showing the
adaxial side of the calyx limb covered with purple pustules, H. Thickened pulvinate structure on the calyx limb, I. Lateral and back view
of the flower, J–K. Top and lateral view of the gynostemium, showing the paired anthers and their position, L. Adaxial (upper) and abaxial
(down) side of the leaf, M–N. Taproot and root tips.
A NEW SPECIES OF ARISTOLOCHIA FROM CHINA Phytotaxa 675 (3) © 2024 Magnolia Press 265
FIGURE 2. Line drawing of Aristolochia pulvinata by Ms. Xiao Li. A. Habit, showing alternate leaves and axillary inflorescences, B.
Abaxial view of the leaf, showing palmate venation, C. Cauliflorous habit on lignified branches, DE. Longitudinal section and frontal
view of the flower. F. Thickened pulvinate structure on the calyx limb, GH. Gynostemium and pedicel, IJ. Lateral and transverse
sections of the root, showing three xylem ray clusters.
Etymology:—The specific epithet "pulvinata" is derived from the distinctive pulvinate thickening on the inferior
lobe of the adaxial side of the calyx limb observed in its flowers. The subgenus Siphisia is commonly referred to as
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266 Phytotaxa 675 (3) © 2024 Magnolia Press
木通 (guan mu tong) in Chinese, which differs from the genus name Aristolochia, typically known as 马兜铃 (ma dou
ling). Therefore, the Chinese name is given as 垫状花关木通 (dian zhuang hua guan mu tong), reflecting this unique
morphological trait.
Additional specimen examined (paratype):—CHINA. Yunnan province, Dali Bai autonomous prefecture,
Yongping county, Shanyang town, Jinguangsi nature reserve, 25°11´N, 99°32´E, 2228 m, 08 May 2024, flowering, H.
L. Zhang & T. Zhu JGS1116 (SWI25!).
Similar species and phylogenetic position:—Aristolochia pulvinata displays close floral morphological
similarities with its sympatric species, A. ovatifolia and A. utriformis, especially in the dark purple, glabrous, and
velvety texture of the adaxial calyx tube. Additionally, these species exhibit an anachroid villous adaxial surface
of the calyx utricle, a feature consistent across the taxa. Together with A. luudamcui and A. melanocephala, these
species demonstrate varying degrees of thickening at the calyx throat, as depicted in Figure 3 A2, B2, C2, D2, E2 and
detailed in Table 1. However, the characters of the thickening—specifically its shape, texture, angle, and degree—in
A. pulvinata are distinctly different from those observed in the aforementioned species.
FIGURE 3. Morphological comparison. A1A5: Aristolochia pulvinata, B1B5: A. ovatifolia, C1C5: A. melanocephala, D1D5: A.
utriformis, E1E5: A. neolongifolia. A1, B1, C1, D1, E1: Lateral view of the flower; A2, B2, C2, D2, E2: Longitudinal section view of
the flower; A3, B3, C3, D3, E3: Front view of the flower; A4, B4, C4, D4, E4:: Gynostemium; A5, B5, C5, D5, E5: Abaxial (upper right)
and adaxial (lower left) sides of the leaf. C1C5 were provided by Dr. Xinxin Zhu.
A NEW SPECIES OF ARISTOLOCHIA FROM CHINA Phytotaxa 675 (3) © 2024 Magnolia Press 267
Furthermore, the morphology of the saccate structure formed by the calyx limb varies significantly among these
taxa. Aristolochia pulvinata is distinctly characterized by a semi-open, bucket-like shape due to its relatively wide,
triangular opening, with the interior densely lined with purple, granular pustules. In contrast, A. ovatifolia and A.
utriformis exhibit a narrow, elongated conical structure with a constricted opening; A. ovatifolia lacks any bumps on
the internal surface of the limb, while A. utriformis features sparse papillae. A. melanocephala is easily recognizable
by its elongated tubular calyx limb adorned adaxially with densely packed, black-tipped palliae.
This study also included comparisons with A. luudamcui (Phan et al. 2021) and A. neolongifolia, both of which
can be readily differentiated from A. pulvinata by their yellow-colored adaxial perianth calyx tube and limb. Detailed
morphological comparisons and additional information are provided in Figure 3 and Table 1.
TABLE 1. Morphological comparison of A. pulvinata with similar species.
Character A. pulvinata* A. ovatifolia* A. melanocephala**
Leaf
shape Lanceolate, entire margin; apex
acute; base cordate Orbicular—ovate to ovate-cordate Ovate to deltoid; apex acute; base
cordate
size 6–15 × 3–8 cm 5–13 × 4–8 cm 8–20 × 5–11 cm
pubescence
(adaxial side) Appressed to sparsely pubescent Villous to sericeous Appressed to villous
Inflorescence
Flowers axillary on young stems,
1–2 per fascicle; on lignified stems,
cauliflorous, 2–5 per fascicle
Axillary, solitary flower
Axillary, solitary flower;
cauliflorous on lignified old stems,
solitary
Perianth
calyx utricle
(adaxial side)
Cylindric, 0.6–1.2 × 0.6–1.0 cm; dark
purplish, arachnoid villous
Cylindric to spherical, 0.4–0.9 ×
0.5–1.0 cm; dark purplish, arachnoid
villous
Cylindric to spherical, 0.5–0.9
× 0.5–1.0 cm; dark purplish,
arachnoid villous
calyx tube
****
(adaxial side)
U–G: 1.0–1.4 cm, purplish, glabrous,
velvety, ridged with veins; G–T: 1.2–
1.8 cm, purple to reddish, glabrous,
velvety, gourd-shaped tube; near
throat region darkens to near black
for 0.2–0.3 cm
U–G: 1.0–1.2 cm, purplish, glabrous,
velvety, ridged with veins; G–T:
1.5–1.8 cm, dark purple, glabrous,
velvety
U–G: 1.5–2.0 cm, white with
purple spots, glabrous, velvety,
ridged with veins; G–T: 1.6–2.4
cm, white with purple spots,
glabrous, waxy
calyx limb
(adaxial side)
Semi-open saccate, 0.9–1.5 cm long,
1.0–1.2 cm in diameter, abaxially
purplish red to yellowish green;
densely covered with dark purple
granular pustules
Saccate, cylindric or conical, 1–2 cm
long, dark purple, smooth, velvety
Cylindric, 3 cm long × 1.5 cm;
white with densely covered black-
tipped papillae
calyx throat
Throat ca. 1–2 mm in diameter; oval
pulvinate area eccentrically surround
throat; thickest in the middle, 0.3–0.5
cm, edge thin, sparsely covered with
purple pustules
Throat ca. 1 mm in diameter, whitish
to yellowish; throat with a purple
annular structure, volcanic crater-like
Throat ca. 1–1.5 mm in diameter,
whitish to yellowish; throat with
a ca. 0.8 mm thickened annular
structure dotted with purple,
volcanic crater-like
......continued on the next page
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268 Phytotaxa 675 (3) © 2024 Magnolia Press
TABLE 1. (Continued)
Character A. utriformis* A. neolongifolia* A. luudamcui***
Leaf
shape Lanceolate to linear;
apex acute; base auriculate
Ovate to linear; apex acute or
acuminate; base cordate to auriculate-
cordate
Narrowly ovate to lanceolate; apex
acuminate; base cordate
size 10–17 × 3–4 cm 10–18 × 1.5–3 cm 7–11 × 3–4 cm
pubescence
(adaxial side) Sparsely villous Sparsely pubescent Sparsely pubescent
Inflorescence Axillary, 1–2 per fascicle
Axillary, solitary, flower terminal;
no flower observed on lignified old
branches
Flower terminal, solitary or paired,
axillary or sometimes along old
branches
Perianth
calyx utricle
(adaxial side)
Cylindric to spherical, 1.0–1.5 ×
1.0–1.5 cm; purplish red, arachnoid
villous
Cylindric, 0.3–0.5 × 0.3–0.6 cm; a
yellow annular band surrounds the
base of the gynostemium, rest part
dark-purple bands; arachnoid villous.
Cylindric, 0.5–0.6 × 0.6–0.8 cm;
covered by trichomes sparsely and
a dark-purple patch
calyx tube
****
(adaxial side)
U–G: 2.0–3.0 cm, purple, glabrous,
velvety; G–T: 2.5–3.5 cm, purplish
red, glabrous, velvety
U–G: 0.5–1.0 cm, glabrous, yellow,
waxy; G–T: 0.6–1.0 cm, velvety
purple band as close to throat
0.8–0.9 cm high, 0.6–0.8 cm in
diameter, inner surface reddish-
purple, glabrous
calyx limb
(adaxial side)
Saccate, conical, 2.5–3 cm × 1.2–1.8
cm in diameter; black-purple, sparse
processes or pustules
3-dentate at apex; glabrous, waxy,
yellow in the major part with a purple
patch or band near the throat
Saccate, cylindric, 2.6–3 × 0.7–1.2
cm; yellow and glabrous
calyx throat
Throat ca. 1.5–2 mm in diameter,
purplish red; throat opening with a
1 mm thickened annular structure,
volcanic crater-like
Throat ca. 0.5 mm in diameter, purple,
waxy; no thickening, surrounded by
small processes
Throat ca. 1 mm in diameter,
yellow; semicircle-like, dark-
yellow annulus at throat
* Measured by this study
** Following original description of A. melanocephala (Zhu et al. 2018)
*** Following original description of A. luudamcui (Phan et al. 2021)
**** U–G–T = utricle to geniculation to throat
Conservation status:—Aristolochia pulvinata is currently known only from its type locality and, like many
members of Aristolochia subg. Siphisia, exhibits high endemism, being restricted to a narrow habitat (Luo et al.
2020; Huang et al. 2022). With an estimated population size of only about 100 individuals, this species is potentially
vulnerable. The genus Aristolochia is known for its critical role as host plants for multiple swallowtail butterfly species
(Lepidoptera: Papilionidae). Particularly, the sympatric species A. ovatifolia has been confirmed as a local host for
Bhutanitis lidderdalii (Zhang et al. 2019), a critically endangered butterfly listed under CITES Appendix II (2024).
This relationship underscores the potential ecological importance of Aristolochia pulvinata, suggesting its possible
role in butterfly conservation and highlighting the need for comprehensive conservation assessments.
During our fieldwork in Yunnan province, it was observed that multiple Aristolochia species are indiscriminately
A NEW SPECIES OF ARISTOLOCHIA FROM CHINA Phytotaxa 675 (3) © 2024 Magnolia Press 269
exploited for use in traditional Chinese medicine (TCM), largely due to their morphological similarities when not in
flower. Specifically, Aristolochia pulvinata has only been found in a very limited and concentrated area (<10km2),
with no observed fruiting or seed production this year. This could indicate it potentially facing a pollination challenge,
necessitating further ecological and reproductive studies.
Given these findings, it is recommended to classify Aristolochia pulvinata as Critically Endangered (CR) under
the IUCN Red List criteria B2ab; C2a (i, ii). This assessment is based on its extremely restricted distribution to a single
location, the isolated and high endemic nature of its population, the absence of fruiting, the exploitation risks from
local traditional medicine practices, and its ecological significance. This recommendation aligns with the guidelines
provided by the IUCN Standards and Petitions Committee (2024).
Discussion
The discovery of new species within the genus Aristolochia, particularly within the subgenus Siphisia, has seen a
significant surge in recent years, with southwest China and northern Vietnam emerging as key centers of diversification
for this clade (Ohi-Toma et al. 2006; Wanke et al. 2006). While the addition of new taxa is a welcome advancement for
the scientific community, it also highlights several urgent challenges that require immediate attention.
Foremost among these challenges is the precarious conservation status of many species within the Siphisia
clade. Despite recent taxonomic descriptions formally recognizing these species, many have long been subject to
traditional exploitation, often in unregulated medicinal markets. During our fieldwork, it was not uncommon to observe
Aristolochia specimens being traded in such markets without any oversight. Some newly described species, including
Aristolochia pulvinata, exhibit alarmingly small population sizes and highly restricted distributions, exacerbating their
vulnerability.
Consequently, a critical issue arises from the balance between scientific transparency and conservation concerns.
Although the precise localities of rare species are often disclosed in the interest of scientific rigor and reproducibility,
doing so in the case of Aristolochia may pose significant risks. The rising market demand for Aristolochia species,
coupled with the lack of regulatory frameworks and legal protections for these plants, could lead to increased exploitation
of already endangered populations if locality data were made publicly accessible.
In the case of A. pulvinata, we have chosen not to disclose specific locality information within this paper, in an
effort to mitigate potential conservation threats. However, in keeping with principles of scientific integrity, all data
related to this species have been securely archived in trusted institutions. We welcome verified requests for access to
these data for legitimate scientific or educational purposes, and interested parties are encouraged to contact the authors
directly.
Another significant challenge facing Aristolochia research is the pressing need for a comprehensive systematic
analysis to clarify the evolutionary relationships within this group. While many recent species descriptions, including
this research, have been validated through morphological diagnosis, the rapid development of sequencing technologies
and advanced analytical tools provides an opportunity to incorporate molecular evidence. Such evidence is crucial for
shedding light on the speciation processes underlying the emergence of numerous new species in this clade. Although
A. pulvinata is readily distinguishable by its floral morphology, which clearly supports its recognition as a distinct
taxon, its sympatry with A. ovatifolia and the presence of shared traits, such as the velvety epidermis on the interior
calyx tube and the connate limb structure, raise intriguing evolutionary questions. These shared features prompt further
inquiry into how these species evolved, what mechanisms drove their divergence, and the timing of these events.
The primary aim of this study is to validate Aristolochia pulvinata as a new species, but it is hoped that the findings
presented here will contribute to broader research efforts and stimulate further investigation into the evolutionary
history of this group.
Acknowledgements
The authors are grateful to Jinguangsi Nature Reserve in Yongping, Dali, for fieldwork support under project contract
(No. 2023-538). Special thanks go to the New York University Center for Environmental and Animal Protection (CEAP)
for partially funding this research. Appreciation is extended to Ms. Xiao Li for her exquisite scientific illustrations. The
authors also thank Dr. Shuai Liao and Mr. Dechang Meng from the South China Botanical Garden, Chinese Academy
ZHANG ET AL.
270 Phytotaxa 675 (3) © 2024 Magnolia Press
of Sciences, and Dr. Xinxin Zhu from Xinyang Normal University for their valuable insights into the taxonomy and
phylogeny of the Aristolochiaceae family, as well as for providing essential images. Further gratitude is directed to Dr.
Joyce G. Onyenedum from New York University for her insightful and tremendous guidance in botanical expertise.
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