Research Article |
Corresponding author: Xin Hong ( hongxin@ahu.edu.cn ) Corresponding author: Li Ding ( dingli@gxib.cn ) Academic editor: Laura Clavijo
© 2023 Zheng-Long Li, Yan-Yun Kuang, Qing-Qing Xu, Wei-Chuen Chou, Xin Hong, Li Ding.
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, Kuang Y-Y, Xu Q-Q, Chou W-C, Hong X, Ding L (2023) Primulina pingnanensis, a new species of Gesneriaceae from Guangxi, China. PhytoKeys 229: 157-165. https://doi.org/10.3897/phytokeys.229.103735
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A new species of Primulina, P. pingnanensis, from the Guangxi Zhuangzu Autonomous Region, China, is described and illustrated here. It is morphologically similar to P. orthandra but has significant differences in the bracts, corolla tube and lobes shape, as well as in the indumentum of the outer surface of the corolla, the filaments, the staminodes and the anthers. Colorful photographs and essential information of this new taxon are also provided, including detailed taxonomic description, distribution, habitat, the comparison table, and the IUCN conservation status. We also discuss a validation of new combination P. crassifolia and Chirita crassifolia.
Flora of Guangxi, Gesneriaceae, limestone flora, new taxon, Primulina orthandra, taxonomy
As of December 2022, about 250 taxa (including varieties) of Primulina Hance had been published worldwide, with 215 species and 18 varieties distributed in China and 18 species in Vietnam (
In March 2018, when we were on an expedition in Pingnan County, Guangxi, China, we found an unknown Primulina-like plant growing at the crevices of rocks on the top of a limestone cliff. According to its leaf arrangement (rosette), fleshy leaves, tubular corolla, and cracked fruits (capsule with parietal placentation), it should be included in Primulina. However, it did not match any known species of this genus. In addition, this species distinguishes from the genus Petrocodon by its lingulate stigma, curved filaments, and fleshy leaves. We collected specimens in the field and introduced some living plants into cultivation at the nursery of the National Gesneriaceae Germplasm Resources Bank of GXIB and the Gesneriad Conservation Center of China. The morphology of the cultivated plants has not changed from that of the wild plants during the past three years. We compared the collected specimens and living plants with other known type specimens and living plants of Primulina, and we found that it is distinctly different from other species of Primulina, especially those distributed in Guangxi and recently published species of Primulina (e.g.,
The description is based on specimens collected in the wild. The measurements and morphological characteristics of the new species were taken from the type specimens processed by the authors. The type specimens of the new species were deposited in IBK. We examined Primulina specimens in IBSC, K, IBK, KUN, US, PE, and VNMN. We also searched two online herbaria, Chinese Virtual Herbarium (CVH, http://www.cvh.ac.cn) and Chinese Field Herbarium (CFH, http://www.cfh.ac.cn), to find species with similar morphology. We determined it to be an undescribed taxon. All morphological characters were studied under a dissecting microscope and were described using the terminology used by
Primulina pingnanensis morphologically resembles P. orthandra but is distinguished from the latter by bracts lanceolate (vs. ovate), corolla tube funnel-form and no constriction in the middle (vs. tube near tubular with constriction in the middle), outer corolla surface sparsely white puberulent (vs. glabrous), corolla lobes oblong (vs. broadly ovate), filaments strongly curved at the middle (vs. straight), anthers fused from the entire adaxial surface and sparsely barbate (vs. confluent at apex, glabrous), staminodes obvious, 1–1.3 cm long, sparsely pubescent (vs.ca. 1.5 mm long, glabrous). Detailed morphological comparisons with P. orthandra are provided in Table
Morphological comparisons between Primulina pingnanensis and P. orthandra A habit of P. pingnanensis B habit of P. orthandra C lateral view of mature flower of P. pingnanensis D lateral view of mature flower of P. orthandra E staminodes of P. pingnanensis F staminodes of P. orthandra G filaments of P. pingnanensis H filaments of P. orthandra I bracts of P. pingnanensis J bracts of P. orthandra.
Diagnostic character differences between Primulina pingnanensis and P. orthandra.
Character | Primulina pingnanensis | P. orthandra |
---|---|---|
Bracts | lanceolate | ovate |
Tube | funnel-form, no constriction in the middle | tube near tubular, constriction in the middle |
Outer corolla surface | sparsely white puberulent | glabrous |
Corolla lobes | lobes oblong | lobes broadly ovate |
Filaments | strongly bent at the middle | straight |
Anthers | fused by the entire adaxial surface and sparsely barbate | confluent at apex, glabrous |
Staminodes | obvious, 1–1.3 cm long, sparsely pubescent | ca. 1.5 mm long, glabrous |
China. Guangxi Zhuangzu Autonomous Region: Guigang City, Pingnan County, Shuangma Village, 23°37'N, 110°19'E, growing atop a cliff on a limestone hill, 28 March 2018, Chou Wei-Chuen, CWC180328-01 (holotype: IBK!; isotypes: AHU!, IBK!).
Perennial herb. Rhizomatous stem subterete. Leaves basal, opposite, and congested at rhizome apex after years of growth; petiole 5–8 cm long, densely pubescent. Leaf blade dark green, thick herbaceous, elliptic to ovate-elliptic, 15–20 × 6–8 cm, apex acute to obtuse, base broadly cuneate, slightly oblique, margin sinuate, densely pubescent on both surfaces; 3–4 pairs of lateral veins on each side of the midrib; adaxially midrib main vein conspicuously sunken and lateral veins inconspicuously sunken, abaxially midrib main vein and lateral vein conspicuously raised. Cymes 1–7, axillary, 1–3-branched, 1–8(–16)-flowered; peduncles 18–25 cm long, densely brown puberulent and pubescent; bracts 2, opposite, lanceolate, ca. 7 × 2.5 mm, densely brown pubescent on both surfaces. Pedicels 2.5–4 cm long, densely brown puberulent, and pubescent. Calyx 5-lobed from the base, lobes narrowly lanceolate to triangle, apex acute, ca. 4 × 0.9 mm, outside pubescent, inside glabrous. Corolla zygomorphic, lilac, –4.5 cm long, outside sparsely white puberulent, inside glabrous; tube funnel-form, 2.0–3.0 cm long, 1.0–1.3 cm in diameter at the mouth, ca. 5 mm in diameter at the base; limb distinctly 2-lipped; dorsal lip 2-lobed to the middle, lobes ca. 1.0 cm long, apex suborbicular; ventral lip 3-lobed to the middle, lobes oblong, 1.0–1.5 cm long. Stamens 2, glabrous, adnate to the corolla tube for ca. 10 mm above the base; filaments 8–10 mm long, extending outwards at the base of the corolla, strongly curved at 90° degrees at the middle, sparsely white pubescent at base; anthers white, ca. 2 mm long, fused by the entire adaxial surface, sparsely barbate; Staminode 3, lateral ones obvious, linear, sparsely pubescent, 1–1.3 cm long, adnate to the corolla for 8 mm above the base; the middle one capitate, ca.1 mm long, adnate at the corolla base. Disc annular, slightly oblique, ca. 1.5 mm in height, margin repand. Pistil 2.8–3.2 cm long; ovary ca. 1.8 cm long, densely white pubescent; style ca. 1 cm long, densely puberulent; stigma trapeziform, ca. 2 mm long, apex slightly 2-lobed, lobes obtuse triangle, ca. 0.4 mm long. Capsule 4.5–6 cm long, sparsely brown puberulent, narrowly oblong-ovoid, dehiscing loculicidally into two valves.
Flowering from the second half of March to the first half of April, fruiting from June to July.
The specific epithet is derived from the type locality, Pingnan County. This county is the birthplace of Mr. Chou’s mother. Thus, Mr. Chou strongly suggested using “pingnanensis” as the scientific name.
Píng Nán Bào Chūn Jù Tái (Chinese pronunciation); 平南报春苣苔 (Chinese name).
Primulina pingnanensis is only known from the type locality, Shuangma Village, Pingnan County, Guigang City, Guangxi Zhuangzu Autonomous Region, growing on limestone cliffs at an elevation of ca. 50 m. The average temperature in the distribution area is 22.6 °C, while the average annual precipitation is 1050–2100 mm. The habitat is very close to the village with human activities.
The terrain in the North and South of Pingnan County is mountainous, while the central area is flat. Very few limestone hills are in the plains, but some mountains are near Shuangma Village. After finding the new species, we conducted several detailed explorations of the area. The current survey results showed that this species has a small population at the top of a limestone mountain near Shuangma Village, with fewer than 200 individuals. According to the results of our field investigations in the type locality and adjacent regions, the EOO and AOO of Primulina pingnanensis are about 2 km2 and 0.1 km2, respectively. The severe drought in the second half of 2022 has seriously affected the population. According to the field survey, it is preliminarily estimated that the number of individuals in this population has decreased by 40% or more. More in-depth habitat surveys are warranted to determine if there are more populations nearby. For this current study, we temporarily assess the status of this species as Critically Endangered [CR B1+B2ab (iii, v)], according to the IUCN Red List Categories and Criteria (IUCN 2022).
When the new combination for Primulina crassifolia was made by
Chirita crassifolia Aver. & K.S.Nguyen, Pl. Diversity Fl. Veg. Bat Dai Son 254 (2021). Basionym.
Vietnam, Ha Giang Province: Quan Ba district, Tung Vai commune, steep rocky slopes to large and deep cave composed of highly eroded marble-like white limestone, elevation 900–1000 m a.s.l., 17 October 2018, L. Averyanov, Nguyen Sinh Khang, T. Maisak, Truong Duc Thieu, VR 938 (holotype: LE!; isotypes: HN!, LE!).
The Karst and Danxia landforms from south & southwest China to the north Indo-China Peninsula are well-known for their high species diversity and endemism levels. Some interesting genera of Gesneriaceae for example, Primulina, Petrocodon Hance, and Hemiboea Clarke have been attracting the attention of botanists and taxonomists in the past decades. Primulina speciation is positively associated with changes in past temperatures and East Asian monsoons. Climatic change around the mid-Miocene triggered an early burst (
The high species diversity and restricted distributions on limestone habitats have made the calciphilous Primulina an ideal study subject for understanding plant radiation on Sino-Vietnamese limestone karsts (
We thank Stephen Maciejewski, the Gesneriad Society, and Michael LoFurno, Associate Professor, Temple University, Philadelphia, USA, for their editorial assistance. We are also grateful to Michael Möller, Royal Botanic Garden Edinburgh, United Kingdom, for the notes on Primulina crassifolia.
The authors have declared that no competing interests exist.
No ethical statement was reported.
This study was financially supported by the Fund of Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations (PSESP2021F07).
WC, ZL and LD collected this species. ZL, YK, and QX performed the data analysis. ZL and XH wrote the manuscript. LD and XH revised the manuscript. All authors have read and approved the final manuscript.
Zheng-Long Li https://orcid.org/0009-0009-8988-5725
Yan-Yun Kuang https://orcid.org/0009-0001-4964-3969
Qing-Qing Xu https://orcid.org/0009-0007-8725-9291
Wei-Chuen Chou https://orcid.org/0000-0001-6470-9295
All of the data that support the findings of this study are available in the main text.