Research Article
Research Article
A new lithophilous species of Gesneriaceae, Petrocodon rubrostriatus, from the karst area of South Yunnan, China
expand article infoKe Tan, Di-Ya Chen§, Xi-Qiang Song, Ming-Xun Ren
‡ Hainan University, Haikou, China
§ Guilin University of Technology, Guilin, China
Open Access


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.

Key words

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 (Huang et al. 2022; Yang et al. 2022; GRC 2023; POWO 2023; Zhang et al. 2023). Most species of Petrocodon are endemic to karst landscapes (Fan et al. 2020; Li et al. 2020 a, b), except for three species, Petrocodon asterocalyx F.Wen, Y.G.Wei & R.L.Zhang (Zhang et al. 2018), P. chishuiensis Z.B.Xin, F.Wen & S.B.Zhou (Xin et al. 2020), and P. wui F.Wen & R.B.Zhang (Zhang et al. 2023), which are distributed in Danxia landforms. After the revision based on molecular phylogenetic studies, several Chinese monotypic and small genera have been included in Petrocodon, such as Calcareoboea C.Y.Wu ex H.W.Li and Lagarosolen W.T.Wang (Weber et al. 2011), one species of Wentsaiboea D.Fang & D.H.Qin (Weber et al. 2011) and one species of Primulina Hance (Xu et al. 2014). Petrocodon is a genus with one of the highest diversity of floral traits in Chinese Gesneriaceae, which may have resulted from coevolution with their pollinators (Weber et al. 2011).

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.

Materials and methods

Morphological study

All available specimens of Petrocodon s.l. stored in the herbaria (IBK, KUN, and PE) in China, digital specimens on JSTOR Global Plants ( and the Chinese Virtual Herbarium (, and relevant literature (e.g., Weber et al. 2011, 2020; Yang et al. 2022; Zhang et al. 2023) were examined and studied. We carried out morphological observation, measurements, and prepared a description based on living plants, dried specimens, and preserved materials of the new species. We described this new species using the terminology of Wang et al. (1990, 1998), Weber et al. (2011) and Zhang et al. (2023).

Phylogenetic analysis

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 (Chase and Hills 1991). Sequences of the nuclear ribosomal Internal Transcribed Spacer region (ITS) and plastid trnL-F intron-spacer region (trnL-F) of 38 samples representing 24 species and one variety of Petrocodon were downloaded from GenBank (Table 1). Four samples of the new species were newly sequenced for both markers following the DNA extraction, PCR amplification and sequencing protocol of Yang et al. (2022), using the primers for ITS and trnL-F of Taberlet et al. (1991) and Möller and Cronk (1997), respectively. Sequence alignment and phylogenetic analyses of the 44 samples followed Yang et al. (2022), with Primulina dryas (Dunn) Mich.Möller & A.Weber and P. pinnata (W.T.Wang) Yin Z.Wang as outgroups, based on previous phylogenetic analyses (Möller et al. 2009; Weber et al. 2011; Zhang et al. 2018, 2023). A partition homogeneity test (Farris et al. 1995) was conducted in PAUP 4.0a169 (Swofford 2003) with 1000 replicates to determine whether the trnL-F and ITS datasets contained phylogenetic conflict. We performed phylogenetic analyses, based on the combined dataset of trnL-F and ITS sequences using Maximum Likelihood (ML). We employed IQ-TREE v.2.0.6 (Nguyen et al. 2015) with 1000 bootstrap replicates (Hoang et al. 2018). K3Pu+F+G4 was selected as the best model for trnL-F and GTR+F+G4 for ITS using ModelFinder (Kalyaanamoorthy et al. 2017). Tree visualization was carried out in FigTree v.1.4.4 (Rambaut 2018). The tree and sequence matrices are available in the TreeBASE (

Table 1.

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. 1). The four specimens of the new species, P. rubrostriatus, resolved in one clade with maximum support (BS = 100%). The new species together with its most similar species (P. mollifolius) belonged to a moderately-supported subclade (BP = 77%), which was on the first diverging lineage of Petrocodon.

Figure 1. 

Phylogenetic tree of Petrocodon generated by Maximum Likelihood (ML) of combined trnL-F and ITS datasets. Numbers above the branches indicate ML bootstrap values (≥ 50%).

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 2, Fig. 2). In conclusion, both the molecular phylogenetic analysis and morphological comparisons indicated that the new species and P. mollifolius are most closely allied, but could be distinguished.

Figure 2. 

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).

Table 2.

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

Taxonomic treatment

Petrocodon rubrostriatus K.Tan, X.Q.Song & M.X.Ren, sp. nov.

Fig. 2


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 2, 3), but can be easily distinguished from the latter by corolla lobes with red to brownish longitudinal stripes (vs. corolla purely yellow), shorter lanceolate bracts, ca. 4.5 mm long (vs. linear, 12–20 mm long); longer style length ca. 10 mm (vs. 6–8 mm), and staminode insertion at 2.5–3 mm from corolla base (vs. inserted at the corolla base).

Figure 3. 

Petrocodon mollifolius (W.T.Wang) A.Weber & Mich.Möller A adaxial view of flower B opened corolla with two fertile stamens and three staminodes C pistil with disc D dissected calyx lobes E stamens with coherent anthers (Photographs by D.C. Meng).


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.

Vernacular name

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.

Distribution and habitat

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.

Preliminary conservation assessment

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 (IUCN 2022), the category of ‘Critically Endangered’ [CR, B2a,b (iii,iv,v)] is proposed here.

Taxonomic notes

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 (Wei 2018; Wei et al. 2022), P. vietnamensis Z.B.Xin, T.V.Do & F.Wen is endemic of Vietnam (Xin et al. 2021; Wei et al. 2022), P. bonii (Pellegr.) A.Weber & Mich.Möller is distributed from Thailand to Vietnam (GRC 2023, POWO 2023), and P. flavus D.J.Middleton & Sangvir. is an endemic of North Thailand (Middleton et al. 2015). The new species is found in the karst region near the Lixianjiang river, the boundary of China with Vietnam and Laos, and thus, the new species may also extend to these countries. Currently, the new species is tentatively considered an endemic to China until detailed field investigations are carried out in its neigbouring countries.


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.

Additional information

Conflict of interest

The authors have declared that no competing interests exist.

Ethical statement

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).

Author contributions

Data curation: DYC. Writing - original draft: KT. Writing - review and editing: MXR, XQS.

Author ORCIDs

Ke Tan

Di-Ya Chen

Xi-Qiang Song

Ming-Xun Ren

Data availability

All of the data that support the findings of this study are available in the main text.


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