Research Article |
Corresponding author: Xi-Qiang Song ( songstrong@hainanu.edu.cn ) Corresponding author: Ming-Xun Ren ( renmx@hainu.edu.cn ) Academic editor: Michael Moeller
© 2023 Ke Tan, Di-Ya Chen, Xi-Qiang Song, Ming-Xun Ren.
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:
Tan K, Chen D-Y, Song X-Q, Ren M-X (2023) A new lithophilous species of Gesneriaceae, Petrocodon rubrostriatus, from the karst area of South Yunnan, China. PhytoKeys 230: 289-299. https://doi.org/10.3897/phytokeys.230.106358
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A new lithophytic species of Gesneriaceae, Petrocodon rubrostriatus K.Tan, X.Q.Song & M.X.Ren, sp. nov. from Lvchun County, South Yunnan, China, is described and illustrated here. It closest resembles P. mollifolius (W.T.Wang) A.Weber & Mich.Möller, but the new species is differentiated from it by red to brownish-red stripes in the yellow corolla throat and 4.5 mm long bract lobes, a ca. 10 mm long style, and staminodes inserted at 2.5–3 mm from the corolla base. The species is preliminarily assessed as ‘Critically Endangered’ (CR) according to IUCN criteria, since currently only one single locality is known with a few subpopulations on a fragmented limestone cliff, with fewer than 300 individuals.
Didymocarpoideae, flora of Yunnan, limestone, new taxon
Petrocodon Hance is a genus of lithophytic perennial herbs in the Gesneriaceae with currently 49 species and one variety (P. dealbatus var. denticulatus), mainly distributed in the limestone regions of southwestern China, and four species distributed on the northern Indo-China Peninsular (
In early August 2020, the authors carried out a field plant survey in the Lixianjiang river basin of Yunnan province, China. A flowering plant of Gesneriaceae was found growing on the tufa surface of a limestone cliff. Due to its typically lithophytic habit and gross vegetative characteristics, such as infundibuliform corolla, straight filaments, capsules dehiscing 4-valved, and capitate stigma, the authors provisionally determined that it belonged to the genus Petrocodon as originally defined. Some flowering individuals were collected as voucher specimens. Careful examination of those specimens in the lab and of living plants was made to compare vegetative and reproductive organs with other species of Petrocodon. The new taxon of Petrocodon is morphologically most close to P. mollifolius (W.T.Wang) A.Weber & Mich.Möller, but different from the latter mainly by the red stripes inside the pale to bright yellow corolla. Supported by molecular analyses, we confirmed it as a new species of Petrocodon sister to P. mollifolius.
All available specimens of Petrocodon s.l. stored in the herbaria (IBK, KUN, and PE) in China, digital specimens on JSTOR Global Plants (http://plants.jstor.org) and the Chinese Virtual Herbarium (http://www.cvh.ac.cn), and relevant literature (e.g.,
Leaf material of the undescribed species was collected from the type locality in Lvchun County (Yunnan, China) and immediately dried in silica gel for DNA extraction (
Voucher and GenBank accession numbers for the samples used in this study.
Species | Voucher number | trnL-F | ITS |
---|---|---|---|
Petrocodon ainsliifolius W.H. Chen & Y.M. Shui | Y.M.Shui et al. 44071 | HQ632941 | HQ633038 |
CWH88 | KF202298 | KF202291 | |
Petrocodon asterocalyx F.Wen, Y.G.Wei & R.L.Zhang | FW-2013 | KC904957 | KC904954 |
Petrocodon chishuiensis Z.B. Xin, F. Wen & S.B. Zhou | FW-2014 | KF680503 | KF680504 |
Petrocodon coccineus (C.Y.Wu ex H.W.Li) Y.Z.Wang | G80E | FJ501516 | FJ501341 |
CWH14B | KF202299 | KF202292 | |
Petrocodon coriaceifolius (Y.G.Wei) Y.G.Wei & Mich.Möller | M.Moeller & Y.G.Wei MMO 06-913 | HQ632943 | HQ633040 |
Petrocodon dealbatus Hance | LJM-2003-104 | GU350668 | GU350636 |
G12B | FJ501537 | JF697578 | |
LJM1209291 | KR476565 | KR337020 | |
Petrocodon dealbatus var. denticulatus (W.T. Wang) W.T. Wang | Y.G. Wei 2010-03 | JF697590 | JF697578 |
Petrocodon ferrugineus Y.G. Wei | M.Moeller & Y.G.Wei MMO 06-784 | HQ632946 | HQ633043 |
Petrocodon hancei (Hemsl.) A.Weber & Mich.Möller | M.Moeller & Y.G.Wei MMO 08-1342 | HQ632944 | HQ633041 |
– | KC904958 | KC904955 | |
– | KC904959 | KC904956 | |
GDLC05 | KF498253 | KF498051 | |
Petrocodon hechiensis (Y.G.Wei, Yan Liu & F.Wen) Y.G.Wei & Mich.Möller | M.Moeller & Y.G.Wei MMO 07-1077 | HQ632942 | HQ633039 |
– | KR476563 | KR337018 | |
Petrocodon hispidus (W.T. Wang) A.Weber & Mich.Möller | CWH87 | KF202300 | KF202293 |
CWH101 | KF202301 | KF202294 | |
Petrocodon hunanensis X.L. Yu & Ming Li | WF190107-02 | MK941180 | MK941179 |
Petrocodon integrifolius (D. Fang & L.Zeng) A.Weber & Mich.Möller | M.Moeller & Y.G.Wei MMO 06-865 | HQ632940 | HQ633037 |
Petrocodon lithophilus Y.M. Shui, W.H. Chen & Mich. Möller | CWH89 | KF202302 | KF202295 |
CWH103 | KF202303 | KF202296 | |
Petrocodon lui (Yan Liu & W.B.Xu) A.Weber & Mich.Möller | Y.G.Wei 8012 | HQ632938 | HQ633035 |
Petrocodon mollifolius (W.T. Wang) A.Weber & Mich.Möller | HEAC:LJM1108211 | KR476547 | KR337000 |
Petrocodon multiflorus F. Wen & Y.S. Jiang | HJ01-2 | KM232660 | KJ475411 |
Petrocodon nivelolanosus (D. Fang & W.T. Wang) A.Weber & Mich.Möller | – | JF697588 | JF697576 |
Petrocodon pulchriflorus Y.B. Lu & Q. Zhang | Q.Zhang 01 | KX579059 | KX579058 |
Petrocodon retroflexus Q. Zhang & J. Guo | – | KX579061 | KX579060 |
Petrocodon rubrostriatus sp. nov. | 20TK0811008 | OQ955752 | OQ968808 |
20TK0811008 | OQ955753 | OQ968809 | |
20TK0811008 | OQ955754 | OQ968810 | |
20TK0811008 | OQ955755 | OQ968811 | |
Petrocodon scopulorus (Chun) Y.Z.Wang | – | GU350669 | GU350637 |
W.Fang 2010-02 | HQ632947 | HQ633044 | |
LJM06753 | KR476567 | KR337023 | |
Petrocodon tiandengensis (Yan Liu & B.Pan) A.Weber & Mich.Möller | 9413 | JX506850 | JX506960 |
Petrocodon tongziensis R.B.Zhang & F.Wen | Ren-Bo Zhang SBQ09383 | MF872618 | MF872617 |
Petrocodon viridescens W.H. Chen, Mich. Möller & Y.M. Shui | Y.M.Shui et al. 82661 | HQ632939 | HQ633036 |
CWH41 | KF202304 | KF202297 | |
Petrocodon wui F.Wen & R.B.Zhang | WF065 | OQ716553 | OQ694978 |
Primulina dryas (Dunn) Mich.Möller & A.Weber | C7a | FJ501524 | FJ501348 |
Primulina pinnata (W.T.Wang) Yin Z.Wang | G26 | FJ501526 | FJ501349 |
As the partition homogeneity test for the trnL-F and ITS datasets showed no statistically significant incongruence (P = 0.09), the datasets were analysed combined. The aligned matrix of the plastid gene (trnL-F: 846 bp) and nuclear region (ITS: 693 bp) comprised 1539 bp, of which 1151 sites were identical, 237 (15.4%) were parsimony informative, and 151 parsimony-uninformative variable characters.
The phylogenetic tree revealed that all sampled Petrocodon taxa clustered together were monophyletic (BP = 100%) (Fig.
In comparing the morphology between the new species (P. rubrostriatus) and the other species in Petrocodon, we found that the morphologically most similar species was P. mollifolius, but can be easily distinguished by its red to brownish-red stripes in the yellow corolla throat and corolla lobes. Other characters, such as bract size and insertion of staminodes inside corolla, pistil indumentum, disc margin and other characteristics also distinguished the two species (Table
Petrocodon rubrostriatus K.Tan, X.Q. Song & M.X.Ren, sp. nov. A habitat B habit C underside of plant D oblique side view of flower and buds E cyme F bracts and flower bud G dissected calyx lobes, pistil with opened corolla H front view of flower I side view of flower J stamens with coherent anthers K dehisced capsule (Photographs by D.C. Meng).
Morphological comparison between Petrocodon rubrostriatus and P. mollifolius.
Characters | P. rubrostriatus | P. mollifolius | |
---|---|---|---|
Leaf blade | Shape | elliptic, broadly elliptic to ovate, or rhombic ovate | ovate to narrowly ovate, or ovate-oblong |
Bracts | Shape | lanceolate | linear |
Length | ca. 4.5 mm long | 12–20 mm long | |
indumentum | abaxially pubescent, adaxially nearly glabrous | both sides densely puberulent | |
Calyx | Shape | broad lanceolate | lanceolate-linear |
indumentum | sparsely puberulent | densely villous | |
Corolla | Shape | infundibuliform corolla tube | nearly tubular |
colour | pale yellow with two or three red to brownish longitudinal stripes | pale yellow without stripes | |
Filament | Length | ca. 8 mm long | ca. 6.5 mm long |
indumentum | sparsely eglandular and glandular-puberulent from the middle to the top, and glands from the middle to the bottom | glandular puberulent | |
Pistil | Length | ca. 21 mm long, ovary 10 mm long and style ca. 10 mm long | ca. 17 mm long, ovary 10 mm long and style 6 mm long |
indumentum | densely puberulent | densely glandular- pubescent | |
Staminodes | 3, inserted at 2.5–3 mm from corolla base | 3, inserted at corolla base | |
Disc | sinuate | annular |
The new species resembles Petrocodon mollifolius (W.T.Wang) A.Weber & Mich.Möller in leaf blade shape and size, flower base colour and size (Figs
China. Yunnan Province: Lvchun county, Banpo township, Emaluoba community, 22°36'N, 102°16'E, altitude ca. 390 m, August 13, 2020, Ke Tan 20TK0811008 (Holotype: IBK! IBK00449896; Isotypes: HUTB, IBK! IBK00449897)
Perennial herb. Rhizomatous stem 1–2 cm long, 5–8 mm in diam., sometimes inconspicuous. Roots fibrous, numerous, pale brown to brown. Leaves in a densely crowded basal rosette, (6–)9–12; petioles 1.5–4 cm long, densely whitish villous; lamina adaxial surface dark green, abaxial surface green, both surfaces whitish pubescent, herbaceous, elliptic, broadly elliptic to ovate, or rhombic ovate, 5.5–11.5 × 2.3–3.5 cm, margin serrate; 4–5 pairs of lateral veins on each side, ascending, tertiary venation also distinctive; apex acute, occasionally obtuse, base cuneate, occasionally asymmetric. Inflorescences 1–4 per plant, axillary, cymose, 3–5-flowered; peduncles green to pale brownish green, puberulent, interspersed with a few longer hairs, 6.5–8.5 cm long; bracts 2, opposite, green to pale green, lanceolate, ca. 4.5 mm long, ca. 1 mm across at base, abaxially pubescent, adaxially nearly glabrous, margin entire; bracteoles 2, opposite, narrowly triangular, colour and hairs same as bracts; pedicels 8–12 mm long, ca. 1 mm in diam., hairs same as peduncle. Calyx 5-sect to base, lobes green to pale green, lanceolate, ca. 2.5 × 0.5 mm, abaxially pubescent, adaxially nearly glabrous, margin entire. Corolla pale yellow to bright yellow, 1.9–2.2 cm long, base near-spherical, outside pubescent interspersed with few glandular hairs, inside glabrous; tube infundibuliform, tubular at the base and widening around the middle, ca. 15 mm long, ca. 4 mm in diam. at the base, ca. 7.5 mm in diam. at orifice, abaxial lip much longer than adaxial lip, adaxial lip 2-lobed to near base, slightly obliquely semicircular, lobes ca. 8 mm long, ca. 6 mm wide at base, margin entire, apex rounded, each lobe with two to three red to brownish-red longitudinal stripes, abaxial lip 3-lobed to more than middle, elliptical, lateral ones slightly oblique and smaller than the central one, lobes ca. 13 mm long, ca. 5 mm wide at base, margin entire, apex rounded, each lobe with one red to brownish-red longitudinal stripe. Stamens 2, inserted in tube ca. 6 mm from corolla base; filaments pale green, ca. 8 mm long, straight, sparsely eglandular and glandular puberulent from the middle to the top and with glands from the middle to the bottom; anthers pale brownish yellow, elliptic, ca. 1.5 × 2.2 mm, glabrous, cohering face to face; staminodes 3, inserted 2.5–3 mm from corolla base, ca. 2 mm long, glabrous. Disc brownish green, ca. 0.9 mm high, glabrous, margin sinuate. Pistil ca. 21 mm long; ovary pale green, densely puberulent, ca. 10 mm long, ca. 1 mm wide; style whitish green, ca. 10 mm long, sparsely eglandular pubescent; stigma pale green, ca. 1 mm long, ca. 0.7 mm wide, disc-like. Capsule cylindrical, green when young, 1.7–2.1 cm long, ca. 1.5 mm wide, pubescent, becoming grey-brown and dehiscing into four valves when mature. Seeds unappendaged, long ellipsoid, ca. 0.4 mm long, ca. 0.2 mm wide.
Flowering in August, fruiting from October to November based on field observations.
The name rubrostriatus refers to the bright red to brownish stripes in the yellow corolla. This is noticeably different from the corolla colours of previously published Petrocodon species.
Hóng Wén Shí Shān Jù Tái (红纹石山苣苔). The first two words, “Hóng Wén”, mean red stripes of the corolla, and the following four words, “Shí Shān Jù Tái”, mean Petrocodon in Chinese.
Petrocodon rubrostriatus is only known from the type locality, near Lixianjiang river, Emaluoba community, Banpo township, Lvchun county, Yunnan. The species grows on moist, shady tufa surfaces of a limestone cliff in a monsoon rainforest at ca. 400 m. Thus, it is exposed to a warm environment with high air humidity in a moderately shaded monsoon rainforest.
Petrocodon rubrostriatus is currently only known from the type locality in the Lixianjiang river basin, where only one small population was observed. In total in 2020, there were fewer than 300 mature individuals in five separate subpopulations, clustered together in a fairly small site of ca. 100 m2, on a moist cliff on the rock surface of an unnamed limestone hill close to the Lixianjiang river. The area of occupancy (AOO), is significantly smaller than the smallest AOO unit of IUCN (10 km2 for Critically Endangered under B2). In 2022, we revisited the type locality and observed a decline in habitat quality caused by a prolonged drought in Southwest China, and a reduction in mature plants to only about 100. This suggests that the new species is extremely vulnerable and easily disturbed by the persistent drought and also the activities of local people. According to the IUCN red list criteria (
The new species is morphologically similar to Petrocodon mollifolius, but most easily distinguished by the longitudinal stripes of red to brownish-red on the petal lobes. With the new species here, there are now 50 species and one variety in Petrocodon, and 47 species are distributed in China. South and Southwest China are the distribution and diversity centres of Petrocodon. The distribution pattern of a few species extends to the northern Indo-China Peninsula, namely P. coccineus (C.Y.Wu ex H.W.Li) Yin Z.Wang and P. hispidus (W.T.Wang) A.Weber & Mich.Möller which are both distributed in South China and Northern Vietnam (
We greatly thank De-Chang Meng for taking the photographs. We also thank Stephen Maciejewski, The Gesneriad Society, and Michael LoFurno, Associate Professor, Temple University, Philadelphia, USA, for their editorial assistance. Finally, we thank the two reviewers, and we extend special thanks to the subject editor, Michael Möller, for his very thoughtful and constructive criticisms.
The authors have declared that no competing interests exist.
No ethical statement was reported.
This work was financially supported by grants from the Hainan Provincial Natural Science Foundation of China (321QN185 & 422RC594) and the Fund of Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain (No.22-035-26).
Data curation: DYC. Writing - original draft: KT. Writing - review and editing: MXR, XQS.
Ke Tan https://orcid.org/0000-0002-9036-163X
Di-Ya Chen https://orcid.org/0000-0002-4164-8183
Xi-Qiang Song https://orcid.org/0000-0001-7690-707X
Ming-Xun Ren https://orcid.org/0000-0002-4707-2656
All of the data that support the findings of this study are available in the main text.