Research Article |
Corresponding author: Wei Guo ( gwei717@163.com ) Corresponding author: Qiang Fan ( fanqiang@mail.sysu.edu.cn ) Academic editor: Peter Boyce
© 2023 Long-Yuan Wang, Wan-Yi Zhao, Zai-Xiong Chen, Wei-Cheng Huang, Ming-Yan Ding, Jin-Chu Luo, Wen-Bo Liao, Wei Guo, Qiang Fan.
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.
Citation:
Wang L-Y, Zhao W-Y, Chen Z-X, Huang W-C, Ding M-Y, Luo J-C, Liao W-B, Guo W, Fan Q (2023) Commelina danxiaensis (Commelinaceae), a new species from Guangdong, China. PhytoKeys 218: 117-126. https://doi.org/10.3897/phytokeys.218.91199
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Commelina danxiaensis (Commelinaceae), a remarkable new species from Mount Danxia, Guangdong Province, China, is described and illustrated. This species is similar to C. communis in inflorescences and flowers but readily distinguishable in its nearly erect stems, larger flowers, and different petal colouration.
Commelinales, morphology, Mount Danxia, phylogeny, taxonomy
Commelina L. is the largest genus of Commelinaceae, consisting of about 170 species distributed in tropical and subtropical regions (
During our botanical investigation of Mount Danxia of Guangdong Province in 2019–2020, we found an unusual population of Commelina. The plants are most closely similar to C. communis L., a species widely distributed in Asia, but differ mainly by the ascending stems (vs. creeping), petals sky-blue with a white basal third (vs. evenly dark blue).
Morphological observations of the putative new species and its close relatives were carried out based on living plants in the field, as well as on dried specimens. The voucher specimens were deposited in the Herbarium of Sun Yat-sen University (
The multiple sequences of each gene were aligned with Clustal X (
The ML phylogenetic tree based on nrITS (Fig.
China. Guangdong: Shaoguan City, Renhua County, Mount Danxia, 24°56'29.73"N, 113°45'21.96"E, dry mountaintop, ca. 350 m elev., 23 May 2020, Q. Fan 17910 (holotype:
Commelina danxiaensis is morphologically similar to C. communis due to their diffuse stems, lanceolate leaf-blades and approximate floral forms. However, it differs in its ascending stems (Fig.
Commelina danxiaensis sp. nov. A habitat, growing on top of the Danxia landform B habit, plants ascending C–E leaf-blade, lanceolate to ovate-lanceolate F leaf-sheaths, with pubescence G–H flower I inflorescence J spathe K fruit in transverse section, 2 seeds per valve L seed. Scale bars: 1 cm (D, E, G, I, J); 3 mm (K, L).
Herbs over 30 cm tall, annual. Roots thin, fibrous. Stems ascending, many-branched; young shoots tomentose, becoming glabrous when old, hairs hyaline. Leaves spirally-alternate, evenly distributed along the stems; sheaths tomentose, hairs hyaline, margin ciliate, hairs setose, white; blades 3–9 × 1.5–2.0 cm, lanceolate to ovate-lanceolate, tomentose on both sides, evently, hairs hyaline, base obtuse, margin glabrous, green to light-purple,, apex lanceolate. Inflorescences leaf-opposite, restricted to the apex of the stems; peduncle 1.5–4.0 cm long, tomentose, hairs hyaline; spathe 1.2–2.5 × 1.0–2.2 cm, cordate, 6–8 veined, adaxially tomentose, long pilose hairs sometimes along the veins, hairs hyaline, abaxially glabrous, base cordate, free, margin green, apex acute; upper cincinnus developed, 1-flowered, flower staminate, peduncle ca. 8 mm long, exerted, sparsely tomentose to nearly glabrous, hairs hyaline; lateral cincinnus 2–3-flowered, flowers bisexual, peduncle 5–8 mm long, nearly included, tomentose to nearly glabrous, hairs hyaline. Flowers chasmogamous, bisexual or staminate, strongly zygomorphic; pedicels c. 3 mm long at anthesis, less than 6 mm long in fruit, reflected, nearly glabrous, hairs hyaline; sepals green, membranous, glabrous, dorsal sepal c. 5 × 2 mm, triangular-lanceolate, apex lanceolate, lateral sepals c. 5 mm × 3 mm, widely oblique-elliptic, connate for 3.6–4.2 mm, apex obtuse to round; paired petals short-clawed, claw c. 2–3 mm long, limb c. 1 cm × 1 cm, orbicular to sub-orbicular, sky-blue with a white basal third, medial petal c. 5 × 2 mm, narrowly rhombic, white, nearlly hyaline; staminodes 3, subequal, the medial slightly shorter, filaments c. 3 mm long, antherodes X-shaped, distinctly four-lobed, upper lobes c. 1/2 to the lower ones, yellow, with a dark maroon at centre; lateral stamen filaments ca. 1 cm long, curved, anthers 1.8–2.2 × 1.2–1.4 mm, elliptic; medial stamen filament ca. 5 mm long, anther 2.2–2.4 × 1.8–2.2 mm, saddle-shaped; ovary c. 1 × 1 mm, ovoid, glabrous, 2-locular, ovules 2 per locule, style c. 1.2 cm long, strongly curved at apex, stigma trilobate, white. Capsule c. 5 × 3 mm, ellipsoid, glabrous, equally 2-valved. Seeds 2 per valve, 3–4 × 2–2.5 mm, elliptic, ventrally flattened, testa brown, irregularly pitted.
Commelina danxiaensis flowers from April to July and fruits from June to September.
Commelina danxiaensis is only known from the type locality, Mount Danxia, Renhua County, Guangdong Province, China. Only two populations have been found, with several hundred individuals. It grows on dry mountaintops of the Danxia formation at elevations of 100–350 m.
Commelina danxiaensis has only been found in Mount Danxia within an area of less than 20 km2, making it putatively ‘Vulnerable’ (VU D2) according to the guidelines of the IUCN Red List Categories and Criteria (
(paratypes). China. Guangdong: Shaoguan City, Renhua County, Mount Danxia, fl., 3 July 2020, Q. Fan 18026 (
The new species Commelina danxiaensis is similar to C. communis and C. diffusa in some of its morphological characters, such as lanceolate leaf-blades, cordate spathes free at base, and blue paired petals. Morphological comparisons among them have been listed in Table
Morphological comparison amongst Commelina danxiaensis, C. communis, C. diffusa and C. bicolor D.Q. Wang & M.E. Cheng.
Character | C. danxiaensis | C. communis | C. diffusa | C. bicolor D.Q. Wang & M.E. Cheng |
---|---|---|---|---|
Stem | ascending | creeping | creeping | unknown |
Phyllotaxy | spirally-alternate | distichously-alternate | distichously-alternate | unknown |
Leaf-blades | tomentose | glabrous | glabrous or hispid | unknown |
Leaf-sheaths | tomentose | glabrous | hispid or hispid-ciliate | glabrous |
Flower size | 2.5 × 2 cm | 2 × 1.5 cm | 2 × 1.5 cm | unknown |
Lateral sepals connation | connate | connate | free | unknown |
Lateral petals colour | sky blue, basal third white | dark blue, sometimes lilac or white | light blue, sometimes lilac | upper most part deep-blue, basal part with claws (3 mm long) white |
Medial petal colour | white | white | light blue | white |
Medial petal claw | absent | absent | present | absent |
Medial petal shape | narrowly rhombic | obtrullate | rhombic | oribicular-ovata or broadly ovata |
Medial staminode development | developed | developed | not developed | developed |
Stigma colour | white | white | white | unknown |
Capsule valve number | equally 2-valved | equally 2-valved | unequally 2-valved | 2-valved |
Seed number per valve | 2-seeded | 2-seeded | dorsal valved 1-seeded, ventral valve 2-seeded | 2-seeded |
Seed testa ornamentation | irregularly pitted | irregularly pitted | Double-reticulate | irregularly foveolate |
Additionally, we found the name Commelina bicolor D.Q.Wang & M.E.Cheng described by
Up to the present time, four species of Commelina have been documented in Danxiashan National Nature Reserve, including the new species Commelina danxiaensis. In order to facilitate identification, we here provide a key and checklist for the Commelina species in Mount Danxia.
1 | Spathe margin connate at base, base truncate | C. benghalensis |
– | Spathe margin free at base, base cordate or rounded | 2 |
2 | Spathe narrowly cordate, veins concolourous to the spathe and inconspicuous; medial petal subequal to the laterals; capsules unequally 2-valved | C. diffusa |
– | Spathe cordate, veins dark green and conspicuous; medial petal unequal to the laterals; capsules equally 2-valved | 3 |
3 | Stem ascending; lateral petals sky blue, basal third white | C. danxiaensis |
– | Stem prostrate; lateral petals evenly dark blue, sometimes lilac or white | C. communis |
We are deeply grateful to Ms Rong-En Wu for her excellent illustration of the new species. This study was supported by Guangdong Provincial Special Research Grant for the Creation of National Parks (2021GJGY034), Science and Technology Program of Guangzhou (201803020013; 201903010076), Foundation of Administrative Committee of Danxiashan National Park (20163300071021059) and the Project for Educational Commission of Guangdong Province of China (2020KTSCX368).
Species sequenced | GenBank accessions | Voucher information | |||
---|---|---|---|---|---|
nrITS | matK | rbcL | trnH-psbA | ||
Commelina africana | KR733806.1 | KR734981.1 | KR737249.1 | KR736019.1 | / |
Commelina benghalensis 1 | OQ189896 | OQ164772 | OQ164778 | OQ164784 |
L.Y. Wang 1833 ( |
Commelina benghalensis 2 | MH768093.1 | / | / | / | / |
Commelina benghalensis 3 | MH768094.1 | / | / | / | / |
Commelina benghalensis 4 | ON908416.1 | / | / | / | / |
Commelina communis 1 | OM934863.1 | / | / | / | / |
Commelina communis 2 | MZ489676.1 | / | / | / | / |
Commelina communis 3 | OM934871.1 | / | / | / | / |
Commelina communis 4 | MH703263.1 | / | / | / | / |
Commelina communis 5 | OM934864.1 | / | / | / | / |
Commelina communis 6 | OM934865.1 | / | / | / | / |
Commelina communis 7 | OM934867.1 | / | / | / | / |
Commelina communis 8 | OM934870.1 | / | / | / | / |
Commelina communis 9 | MH710676.1 | / | / | / | / |
Commelina communis 10 | OM934869.1 | / | / | / | / |
Commelina communis 11 | / | OQ164773 | OQ164779 | OQ164785 |
Q. Fan 18145 ( |
Commelina danxiaensis 1 | OQ189892 | OQ164774 | OQ164780 | OQ164786 |
Q. Fan 17910 ( |
Commelina danxiaensis 2 | OQ189893 | OQ164775 | OQ164781 | OQ164787 |
Q. Fan 18026 ( |
Commelina danxiaensis 3 |
OQ189895 |
/ | / | / |
Q. Fan 18232 ( |
Commelina diffusa | OQ189891 | OQ164776 | OQ164782 | OQ164788 |
L.Y. Wang 1831 ( |
Commelina erecta | MG639917.1 | KJ772671.1 | KR737134.1 | KR735729.1 | / |
Commelina paludosa | OQ189894 | OQ164777 | OQ164783 | OQ164789 |
Q. Fan 18247 ( |
Commelina reptans | KR733954.1 | KR735150.1 | KR736643.1 | KR735386.1 | / |
Commelina purpurea | / | GQ248103.1 | EF590514.1 | GQ248272.1 | / |
Floscopa scandens | / | LC540553.1 | AF312255.1 | KY018930.1 | / |
Murdannia edulis | / | MW617988.1 | MW617988.1 | MW617988.1 | / |
Murdannia bracteata | MT358291.1 | / | / | / | / |