Research Article |
Corresponding author: Xin Hong ( hongxin@ahu.edu.cn ) Corresponding author: Fang Wen ( wenfang760608@139.com ) Academic editor: Alan Paton
© 2023 Zheng-Long Li, Zhang-Jie Huang, Da-Wei Chen, Xin Hong, Fang Wen.
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:
Li Z-L, Huang Z-J, Chen D-W, Hong X, Wen F (2023) A new combination and a new synonym of Gesneriaceae in China. PhytoKeys 232: 99-107. https://doi.org/10.3897/phytokeys.232.108644
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Didymocarpus subpalmatinervis W.T.Wang was shown to be conspecific with Petrocodon lithophilus Y.M.Shui, W.H.Chen & Mich.Möller, by checking original literature, examining specimens, tracing specimen collecting history, and conducting field surveys. The results show morphological characteristics and geographical distribution overlaps between these two species. The transfer of Didymocarpus subpalmatinervis to Petrocodon as a new combination with Petrocodon subpalmatinervis (W.T.Wang) F.Wen & Z.L.Li is proposed here, and P. lithophilus is synonymized with P. subpalmatinervis. Color photographs and essential information are also provided, including a detailed comparison of description, distribution, habitat, and the proposed IUCN conservation status.
Didymocarpus, Flora of China, Gesneriaceae, new combination, new synonym, Petrocodon, taxonomy
Didymocarpus Wall. has a complex taxonomic history, saturated with doubtful taxa (
The French Catholic priest Francois Ducloux (1864–1945), the head of the Kunming Church from 1889 to 1945, hired people to collect plant specimens extensively in central and northern Yunnan (
Petrocodon lithophilus was described at the morphological and molecular level from Naigu Stone Forest, Yunnan Province, where Michael Möller and Yu-Min Shui first discovered it in August 2012. It is placed in Petrocodon by some obvious characters of this genus, viz. a rhizomatous rosette with leaves usually rounded or elliptic, mainly in an alternate arrangement, filaments straight, stigma discoid, and fruits dehiscing loculicidally into two valves (
When sorting out the specimens of Didymocarpus sect. Heteroboea of, the type specimen of D. subpalmatinervis (Fr. Ducloux 3711), morphologically, was found to be extremely similar to Petrocodon lithophilus. According to protologue and label information on the type specimen, the type locality of Didymocarpus subpalmatinervis is near Lunan Stone Forest, only 13 kilometers away from Naigu Stone Forest. During field investigations near the type locality of Petrocodon lithophilus, several populations of Didymocarpus aff. subpalmatinervis were also found on the hills. The authors concluded that D. subpalmatinervis is conspecific with Petrocodon lithophilus. Accordingly, it is reasonable to make a new combination P. subpalmatinervis, and reduce P. lithophilus to a synonym.
A thorough comparison of the type material of Petrocodon lithophilus and Didymocarpus subpalmatinervis was made. Their protologues and relevant records were studied intensively. The geographical distribution of the two species was outlined by careful field surveys of the type locality areas. Classical plant taxonomic methods were involved. Major online herbarium databases, including P (https://science.mnhn.fr/institution/mnhn/search), E (http://www.rbge.org.uk/), K (https://www.kew.org/), A (https://huh.harvard.edu/), PE (https://pe.ibcas.ac.cn/index.html) and Chinese Virtual Herbarium (https://www.cvh.ac.cn/), et al., were checked. The only recorded specimens of D. subpalmatinervis stored at P were affirmed and checked, utilizing high-resolution digital images of the type specimen. In addition, the authors observed and recorded morphological characters of Petrocodon lithophilus in the field and examined its type specimen at KUN.
There are numerous distinct morphological characteristics distinguishing Didymocarpus subpalmatinervis from other species within sect. Heteroboea, such as leaves’ margins obtusely or doubly dentate (vs. margin irregularly triangular denticulate), triangular lobes (vs. rounded or oblong lobes), straight filaments (vs. curving), separate anthers (vs. confluent anthers). Detailed morphological comparisons with sect. Heteroboea are provided in Fig.
Morphological comparisons of Didymocarpus subpalmatinervis and sect. Heteroboea A type specimen of D. subpalmatinervis B habit of D. heucherifolius var. yinzhengii C habit of D. cortusifolius D habit of D. yuenlingensis E habit of D. heucherifolius var. gamosepalus F leaves of D. subpalmatinervis G leaves of D. heucherifolius var. yinzhengii H leaves of D. lobulatus I leaves of D. heucherifolius J opened corolla of D. subpalmatinervis, showing lobes and stamens K frontal view of D. yuenlingensis, showing lobes and stamens L frontal view of D. cortusifolius, showing lobes and stamens M frontal view of D. sinoprimulinus, showing lobes and stamens.
Comparing the description of Didymocarpus subpalmatinervis and Petrocodon lithophilus in their protologues, we found consistency in habit, leaves, calyx, corolla, disc, and ovary (indicated by “●” in Table
The description and comparison of the D. subpalmatinervis and P. lithophilus.
Didymocarpus subpalmatinervis W.T.Wang | Petrocodon lithophilus Y.M.Shui, W.H.Chen & Mich.Möller | The similarity in description between the two species | ||
---|---|---|---|---|
Habit | Perennial, stemless herb | Perennial herbs | ● | |
Leaves | shape | leaf blade ovate to oblate | leaf blade rounded or elliptic | ★ |
hair | adaxially densely appressed puberulous, abaxially appressed puberulous, pilose on veins | pubescent on both surfaces | ★ | |
base | cordate | nearly cordate | ● | |
margin | obtusely or doubly dentate | shallowly or deeply crenulate | ★ | |
apex | obtuse | rounded | ★ | |
Cymes | number | Cymes ca. 2, ca. 2× branched, 2–10–flowered; | about10 flowers | ★ |
peduncle | puberulous | pubescent | ★ | |
bracts | 2–3, narrowly lanceolate or linear, puberulous | 2, linear or lanceolate, pubescent | ★ | |
Calyx | Calyx actinomorphic, 5-sect or nearly so, segments linear-triangular, both surfaces puberulous | Calyx 5-lobed to base, segments linear, pubescent | ● | |
Corolla | color | Yellow | light greenish-yellow | ● |
length | 2–2.5 cm | 2.5–2.8 cm | ★ | |
tube | funnelform-cylindric, 1.4–1.7 cm | thin tubular, 1.7–1.9 cm | ★ | |
lobes | upper lip 2-lobed, lower lip 3-lobed, all lobes triangular | adaxial lip 2-lobed, lobes triangular, abaxial lip 3-lobed, lobes triangular | ● | |
Stamens | staminodes | 2 | 3 | ▲ |
Disc | annular | ring-like | ● | |
Pistil | ovary | ovary linear | ovary linear inflated | ● |
hairs | puberulous | pubescent | ★ | |
stigma | depressed capitate | stigma 1, disc-like and undivided | ★ |
Morphological comparison of Didymocarpus subpalmatinervis and Petrocodon lithophilus A–C, F1–I1: D. subpalmatinervis D, E, J, F2–I2: P. lithophilus A holotype P04060419 B isotype P04060165 C isotype P04060418 D holotype KUN-1519980 E Isotype KUN-1519978 F flower G abaxial surface of Leaves H adaxial surface of Leaves I opened corolla J staminodes.
The similarity in protologues prompts us to reconsider the circumscription of Didymocarpus subpalmatinervis and Petrocodon lithophilus.
In 1905, Ducoux collected Didymocarpus subpalmatinervis at the position of Y-dje, near Lou-lan. Lou-lan is the French pronunciation of 路南 (Lùnán) in Chinese, and Y-dje corresponds to 维则 (Wéizé). The scope of Lou-lan is not indicated on the type specimens of D. subpalmatinervis. China in 1905 was still in the era of the Qing Dynasty. Lunan then refers to Lunanzhou, which is now Shilin County. Naigu Stone Forest is included in Lunan County (now Shilin County). Lunan refers to Lunan Stone Forest. Lunan Stone Forest and Naigu Stone Forest are both in the Stone Forest scenic spot today. Our field survey shows only one species of Gesneriaceae with similar morphological characteristics in these two regions. The distribution of the two species thus overlaps no matter which geographical entity Lunan refers to in the past or present.
In summary, based on literature research, geographical distribution, and morphological analysis, we find no discontinuities and recognize Didymocarpus subpalmatinervis and Petrocodon lithophilus as conspecific. Therefore, a new combination, P. subpalmatinervis (W.T.Wang) F.Wen & Z.L.Li, comb. nov. is proposed here.
Didymocarpus subpalmatinervis W.T.Wang, Novon 7(4): 428–429. 1997. Type: China. Yunnan: Y-dje, near Lou-lan, July 1905, Fr. Ducloux 3711 (P: holotype P04060419!; isotypes P04060165!, P04060418!). Basionym.
= Petrocodon lithophilus Y.M.Shui, W.H.Chen & Mich.Möller, Sys. Bot. 39(1): 325. 2014. syn. nov. Type: China. Yunnan: Shilin County, Naigu Stone Forest, alt. 1848 m, on rocks on cliffs, 29 August 2012, Y.M. Shui et al. B2012–078 (KUN: holotype KUN-1519980!; isotype KUN-1519978!).
掌脉石山苣苔 (Zhǎng Mài Shí Shān Jù Tái).
This species is endemic to Shilin County, Yunnan Province, China, growing in narrow cracks on rocks. Accompanying plants include other shade herbs and trees.
Naigu Stone Forest is a famous scenic spot for many tourists. The population of Petrocodon subpalmatinervis is easily affected by human activities. For example, tourists probably collect the conspicuous flowers of P. subpalmatinervis while they visit the scenic spot and walk along the trails among the Karst peaks and hills of Naigu Shilin. As mature individuals are easily damaged, the population will likely gradually decline year by year. According to the results of our field investigation in the type locality and adjacent regions, the EOO and AOO of P. subpalmatinervis are about 800 km2 and 30 km2. Despite the severe drought in the second half of 2022 seriously influencing the plant population, there is still a high number of individuals (more than 5 000) surviving in the scenic spot. In addition, authors also found several small populations (total>1 000) in the Karst landscape surrounding the type locality, Naigu Shilin. Following the IUCN Red List Categories and Criteria (
When Wang published the protologue of Didymocarpus subpalmatinervis, the collection date read 1909. But, on the website of CVH and the herbarium P, the collection date of the information of the specimen we consulted was 1905. Their two different collection years are confusing. We carefully compared the labels of three type specimens of D. subpalmatinervis with the collection number ‘3711’ and found that the collector’s writing habits might have caused this misunderstanding. Ducloux’s personal collection number increased with time like many collectors. For example, the collection number of Berberis bodinieri H.Lév. he collected in 1896 was ‘0004’; in 1904, the collection number of Potamogeton distinctus A. Benn. was ‘2571’; in 1905, he collected Cornus capitata Wall. at the same place (Y-dje near Lou-lan) with the collection number ‘3715’; In 1909, the collection number of Merremia yunnanensis (Courchet & Gagnep.) R.C.Fang has reached ‘6398’. Therefore, it seems likely that the specimens of D. subpalmatinervis with the collection number Fr. Ducloux 3711 were collected in 1905.
For some species published decades or even a hundred years ago, obtaining molecular materials for systematic analysis is challenging because there may be only one type specimen or a few specimens, or they are stored in a foreign herbarium (
The authors are grateful to Mr. Zhen-Hao Feng for his generous support and Dr. Su Liu for his translation of the toponym. We also want to thank Stephen Maciejewski, the Gesneriad Society, and Michael LoFurno, Associate Professor, Temple University, Philadelphia, USA, for their editorial assistance. We are grateful to Bing Liu for his suggestions on taxonomy, University of Chinese Academy of Sciences.
The authors have declared that no competing interests exist.
No ethical statement was reported.
This study was financially supported by the Key Science & Technology Research and Development Project of Guangxi (Guike AD20159091 & ZY21195050), the Basic Research Fund of Guangxi Academy of Sciences (grant no.CQZ-C-1901), the capacity-building project of SBR, CAS (KFJ-BRP-017-68), the Fund of Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations (PSESP2021F07).
ZL, ZH and DC inspected the specimens of the species. ZL, FW, and ZH performed the data analysis. ZL and ZH wrote the manuscript. FW and XH revised the manuscript. All authors have read and approved the final manuscript.
Zheng-Long Li https://orcid.org/0009-0009-8988-5725
Zhang-Jie Huang https://orcid.org/0000-0002-2288-6952
Da-Wei Chen https://orcid.org/0000-0002-8718-8768
All of the data that support the findings of this study are available in the main text.