Research Article |
Corresponding author: Qiang Fan ( fanqiang@mail.sysu.edu.cn ) Academic editor: Bing Liu
© 2024 Min Lin, Qin-Liang Ye, Zhi-Jian Zhang, Wen-Bo Liao, 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:
Lin M, Ye Q-L, Zhang Z-J, Liao W-B, Fan Q (2024) Camellia zijinica (Theaceae), a new species endemic to Danxia landscape from Guangdong Province, China. PhytoKeys 237: 245-255. https://doi.org/10.3897/phytokeys.237.114768
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A new species of the genus Camellia (Theaceae), Camellia zijinica, discovered in the Danxia landscape from Guangdong Province, China, is characterized and illustrated. Phylogenetic analysis based on chloroplast genomes suggested its affinity with C. drupifera, C. oleifera and C. fluviatilis, however, it morphologically differs from all of the latter by leaf shape and size. Phonologically, it most closely resembles C. microphylla, but can be distinguished from the latter by its young branchlets glabrous (vs. densely pubescent), fewer bracteoles and sepals, diverse leaf shape, midvein raised slightly with sparsely pubescent or glabrous (vs. prominently with densely pubescent) and leaf adaxially matt (vs. vernicose) when dried. By morphological and molecular analyses, Camellia zijinica represented a distinct new species of C. sect. Paracamellia.
Camellia, Danxia landscape, morphology, new species, phylogeny
Camellia L. is the largest genus in Theaceae, widely distributed across eastern and southern Asia (
The sect. Paracamellia was initially constructed by Sealy, and the sect. Oleifera was proposed by
During our field investigation of Guangdong Province in 2018, we noticed an unknown Camellia species, which can be easily misidentified as C. microphylla (Merr.) Chien. After several years of field observations and a precise comparison of relevant herbarium specimens, we confirmed it as a new member of the Camellia sect. Paracamellia based on morphological characteristics and molecular traits. In this study, we described and illustrated this new species.
Field observations and collections of the new species were carried out from 2018 to 2023 in Zijin County, Guangdong Province, China. Morphological comparisons of the putative new species with the related species based on living plants, relevant literature and herbarium specimens, including “Flora Reipublicae Popularis Sinicae” (
Fresh leaf materials of individuals were collected and stored in silica gel for subsequent molecular experiments. Whole genomic DNA for each sample was extracted using the modified CTAB method (
We downloaded 50 accessions of chloroplast genomes containing 44 Camellia species and two related species as outgroups from the NCBI. The chloroplast genome sequences were aligned using MAFFT v7 (
Based on morphological observations, C. microphylla, C. brevistyla (Hayata) Coh. St and C. fluviatilis Hand.-Mazz. exhibited morphological similarities with the new species. Among them, C. microphylla most resembles the new species, but C. zijinica has a more diverse leaf shape compared with C. microphylla, including elliptic, oblong-elliptic, obovate-elliptic or oblong-lanceolate, while C. microphylla displays oblong-elliptic or obovate-elliptic leaves, moreover, the leaf adaxially matt when dried (vs. vernicose). Differences between C. zijinica and C. fluviatilis are leaf shape and size, and the latter is lanceolate to narrowly lanceolate leaves, 5–9 × 1–1.5 cm (vs. 2–4.8 × 0.8–1.9 cm). Additionally, the leaf apex of C. fluviatilis is caudate-acuminate, which is a distinctive feature that sets it apart. C. zijinica and C. brevistyla differ not only in the shape and size of their leaves but also in having longer stamens and ovaries in the case of C. brevistyla. Furthermore, the young branchlets of C. zijinica are glabrous, while those of the other species are usually pubescent or glabrescent (Table
Morphological comparisons amongst C. zijinica, C. brevistyla, C. microphylla and C. fluviatilis.
Characters | C. zijinica | C. brevistyla | C. microphylla | C. fluviatilis |
---|---|---|---|---|
Leaf shape and size | elliptic, oblong-elliptic, obovate-elliptic or oblong-lanceolate , 2–4.8 × 0.8–1.9 cm | elliptic, obovate-elliptic, obovate-oblong or obovate, 3–5.5 × 1.5–3 cm | oblong-elliptic or obovate-elliptic , 2–3.5 × 1–1.3 cm | lanceolate to narrowly lanceolate, 5–9 × 1–1.5 cm |
Leaf apices | rounded, acute or acuminate | acute | obtuse, rounded, acute | caudate-acuminate |
Young branchlets | glabrous | pubescent to hirtellous | densely pubescent | puberulent, soon glabrescent |
Petiole length | 1–3 mm | 3–5 mm | 1–2 mm | 2–5 mm |
Bracteoles and sepals | 4–6 | 7–8(-10) | 6–7 | 8–9 |
Petals, shape and size | 4–6, oblong-elliptic to obovate-elliptic, apex retuse, 0.7–1.1 × 0.4–0.5 cm | 5–7, obovate to obovate-spatulate, apex retuse to deeply emarginate, 1–2.5(-3) × 0.4–1(-1.5) cm | 5–7, broadly obovate, apex retuse, 0.8–1.1 × 0.5–0.8 cm | 5–6, oblong-elliptic to oblanceolate, apex rounded to slightly retuse, 0.8–3 × 0.4–2 cm |
Stamens | 4–5 mm | 5–10 mm | 5–6 mm | 5–7 mm |
Capsule shape and size (diameter) | ovoid or subglobose, 1.2 cm | subglobose, 1.5–1.8 cm | ovoid, 1.5 cm | ovoid, 1.5–1.7 cm |
Styles | 3–4, 1–2 mm | 3–4, 4–7 mm | 3, 2–3mm | 3, 4 mm |
Phylogenetic analysis by Maximum likelihood (ML) and Bayesian inference (BI) inferred from chloroplast genomes showed generally common results with highly supported values. The phylogenetic result using ML proved that this new species was sister to C. drupifera, C. oleifera, and successively grouped with C. fluviatilis, C. yuhsienensis, C. granthamiana, C. semiserrata in clade CAI with robust support values (BS = 100) (Fig.
Maximum likelihood phylogenetic tree of C. zijinica and other 46 related species based on chloroplast genomes. Above the nodes of the tree, maximum likelihood ultrafast bootstrap support values were shown. The new species and C. microphylla were highlighted in bold. The red circles marked on the tree nodes indicated differences between the maximum likelihood and Bayesian inference. “CAI” and “CAII” refer to the two clades within CladeA.
China. Guangdong: Zijin County, Guzhu Town, Mount Yuewang, in mixed forests, 23°29'N, 114°44'E, 294 m a.s.l., 22 September 2018, H.W. Wang & Q. Fan 18084 (holotype: SYS00236945! isotypes: IBSC1010670! SYS00236946! SYS00236947! SYS00236948!)
Camellia zijinica sp. nov. A flowering and fruiting branch B flower in front view C fully ripe fruit, tending to split D young fruit in longitudinal section E seeds in obverse and reverse sides F bracteoles and sepals G petals H stamens (incomplete) I ovary in transverse section J pistil in longitudinal section. Illustrated by Yun-Xiao Liu.
Camellia zijinica is morphologically similar to C. microphylla in the flower shape and size, but differs from the latter by its young branchlets glabrous (vs. densely pubescent), the diverse leaf shape (elliptic, oblong-elliptic, obovate-elliptic or oblong-lanceolate vs. oblong-elliptic or obovate-elliptic), midvein raised slightly with sparsely pubescent or glabrous (vs. prominently with densely pubescent), fewer bracteoles and sepals (4–6 vs. 6–7), leaf adaxially matt when dried (vs. vernicose).
Camellia zijinica sp. nov. A habit B, C flowering branch D leaf shape E flower in front view F flower in back view G pistil and ovary H flowering branch, showing the stamens I flowering branch, showing the bracteoles and sepals J fruits, showing young to ripe (a-c) K bracteoles, sepals and petals. Photographed by Zhi-Ming Zhong, Qiang Fan and Min Lin.
Small evergreen shrubs, 2–5 m tall; bark yellowish brown; young branchlets reddish brown, glabrous. Leaf blades elliptic, oblong-elliptic, obovate-elliptic or oblong-lanceolate, 2–4.8 × 0.8–1.9 cm, adaxially dark green, abaxially light green, thick papery to coriaceous; petiole 1–3 mm long, pubescent; midrib prominent on both surfaces, glabrous and sometimes adaxially sparsely pubescent, secondary veins 6–7 on each side, invisible; apex rounded, acute or acuminate; margin serrulate; base cuneate. Flowers solitary, terminal or axillary, 1.5–2.3 cm in diameter, subsessile. bracteoles and sepals 4–6, caducous, outside pubescent at base, inside glabrous, margin ciliate; outer bracteoles and sepals broadly semiorbicular, partial apex bifid; inner bracteoles and sepals suborbicular to oblong-elliptic. Petals 4–6, white, distinct, glabrous, oblong-elliptic to obovate-elliptic, apically 2-lobed, 7–11×4–5 mm. Stamens 33–40, 4–5 mm long, glabrous; outer filament whorl basally connate for 1–1.5 mm. Ovary 3–4-loculed, with 2 ovules per locule, about 2 mm in diameter, tomentose. Styles 3 or 4, 1–2 mm long, connate half from the base, apically 3–4-lobed. Capsule ovoid or subglobose, ca. 1.2 cm in diameter; pericarp 1–2 mm thick, splitting into 3–4 valves. Seeds semiglobose or globose, 9–10 mm in diameter, brown, glabrous.
Flowering from September to December, fruiting from January to September.
The specific epithet refers to Zijin County of Guangdong Province, the type locality of the new species.
Presently, Camellia zijinica is only known from its type locality, Zijin County of northeastern Guangdong. It is distributed in mixed forests of Danxia landscape at altitudes of 200–400 m a.s.l.
Only two populations of a total of about 90 mature individuals were found currently. Thus, the species could be considered as Endangered (EN; D) status according to IUCN Red List criteria (
(paratypes). China. Guangdong: Zijin County, Guzhu Town, near Mount Yuewang, 23°37'N, 115°10'E, 234 m a.s.l., 12 Oct. 2022 (fl. and fr.), Z.M. Zhong 1012 (
Geographically, C. drupifera and C. oleifera are distributed in southern China, belonging to sect. Oleifera. Although they share a similar distribution area with the new species, they exhibit distinct morphological characteristics, such as larger leaves, flowers and fruits compared to C. zijinica. Furthermore, C. fluviatilis, a sympatric species of the new species, shows similarities in gross morphology but can be easily distinguished by leaf shape and size. Instead, C. microphylla is distributed in a different distribution area from the new species, located in the Jiangxi, Guizhou, Zhejiang, Hunan and Anhui Provinces, China, but they most resembled in morphology. Traditionally, the identification of C. microphylla is associated with having the smallest leaves within the sect. Paracamellia (
The phylogenetic tree generated using ML and BI showed C. zijinica was grouped with C. drupifera, C. oleifera (BS = 90) and C. fluviatilis (PP = 0.90) with low support values, implying an unclear relationship among them. However, these species collectively exhibited the closest relationship to the new species. The species within CladeA belong to the sect. Oleifera, sect. Paracamellia, sect. Camellia, sect. Archecamellia, sect. Furfuracea, as classified in Flora Reipublicae Popularis Sinicae (
We are deeply grateful to Dr. Xianggang Shi for his suggestions on our manuscript, Mrs. Yun-Xiao Liu for her excellent illustration and kindly thank Mr. Zhi-Ming Zhong for his great assistance in sampling.
The authors have declared that no competing interests exist.
No ethical statement was reported.
This study was supported by the Guangdong Provincial Special Research Grant for the Creation of National Parks (2021GJGY034) and Guangdong Provincial Ecological Forestry Development Project (2020141).
Formal analysis: ML. Funding acquisition: WBL. Investigation: QLY, QF, WBL, ZJZ. Methodology: ML. Resources: QLY. Software: ML. Supervision: WBL. Validation: QF. Writing – original draft: ML. Writing – review and editing: QF.
Min Lin https://orcid.org/0000-0001-6342-1978
Wen-Bo Liao https://orcid.org/0000-0001-6839-9511
Qiang Fan https://orcid.org/0000-0003-4254-6936
All of the data that support the findings of this study are available in the main text.
Bayesian inference phylogenetic tree of C. zijinica and other 46 related species based on chloroplast genomes. Above the nodes of the tree, Bayesian posterior probabilities support values were shown. The new species and C. microphylla were highlighted in bold. The red circles marked on the tree nodes indicate differences between the maximum likelihood and Bayesian inference. “CAI” and “CAII” refer to the two clades within CladeA.