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I>Petrocodon (Gesneriaceae) in the Limestone Karsts of Guangxi, China: Three New Species and a New Combination Based on Morphological and Molecular Evidence

Authors:
  • Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and Chinese Academy of Sciences
  • Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and the Chinese Academy of Sciences
  • Guangxi Forestry Survey&Design Institute

Abstract and Figures

Abstract— Based on morphological and molecular data, three new species of the Old World Didymocarpoid Gesneriaceae, Petrocodon laxicymosus , P. longgangensis , and P. pseudocoriaceifolius , are described and illustrated from Guangxi, China. The three new species are most similar to P. coriaceifolius, differing by their texture, size, and shape of leaves, size and pubescence of inflorescence and corolla, anther shape, and pistil length. Additionally, Primulina guangxiensis, one of two species included in Primulina before its recent recircumscription, was unexpectedly found to be nested within Petrocodon in our ongoing phylogenetic analyses, prompting us to make the new combination Petrocodon guangxiensis . The four species of Petrocodon treated here are all rare, known only from a single or a few localities of limestone karsts in Guangxi.
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Systematic Botany (2014), 39(3): pp. 965–974
©
Copyright 2014 by the American Society of Plant Taxonomists
DOI 10.1600/036364414X681437
Date of publication 05/27/2014
Petrocodon (Gesneriaceae) in the Limestone Karsts of Guangxi, China: Three New Species
and a New Combination Based on Morphological and Molecular Evidence
Wei-Bin Xu,
1
Tao Meng,
1
Qiang Zhang,
1
Wang-Hui Wu,
2
Yan Liu,
1,4
and Kuo-Fang Chung
3,4
1
Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and the Chinese Academy of Sciences,
Guilin 541006, China.
2
College of Agriculture, South China Agricultural University, Guangzhou 510642, China.
3
School of Forestry and Resource Conservation, National Taiwan University, Taipei 10617, Taiwan.
4
Authors for correspondence (gxibly@163.com; kuofangchung@ntu.edu.tw)
Communicating Editor: Roland Roberts
Abstract—Based on morphological and molecular data, three new species of the Old World Didymocarpoid Gesneriaceae, Petrocodon
laxicymosus, P. longgangensis,andP. pseudocoriaceifolius, are described and illustrated from Guangxi, China. The three new species are
most similar to P. coriaceifolius, differing by their texture, size, and shape of leaves, size and pubescence of inflorescence and corolla, anther
shape, and pistil length. Additionally, Primulina guangxiensis, one of two species included in Primulina before its recent recircumscription, was
unexpectedly found to be nested within Petrocodon in our ongoing phylogenetic analyses, prompting us to make the new combination
Petrocodon guangxiensis. The four species of Petrocodon treated here are all rare, known only from a single or a few localities of limestone
karsts in Guangxi.
Keywords—Lagarosolen, molecular taxonomy, Old World Didymocarpoid Gesneriaceae, Primulina, rare and endangered plants,
Sino-Vietnamese limestone karst.
As traditionally defined, Petrocodon Hance (Gesneriaceae)
is a genus of four species characterized by small, white, urceo-
late corollas (Hance 1883; Wang et al. 1998; Li and Wang 2004;
Wei 2010; Wen et al. 2012). Recent molecular phylogenetic
studies, however, show that Petrocodon is not monophyletic
and that it is embedded within a strongly supported clade
composed of the polyphyletic genus Lagarosolen W. T. Wang,
two species of Didymocarpus Wall., one species of Wentsaiboea
D. Fang & D. H. Qin, and the monotypic genera Calcareoboea
C. Y. Wu ex H. W. Li, Dolicholoma D. Fang & W. T. Wang,
Paralagarosolen Y. G. Wei, and Tengia Chun (Mo
¨
ller et al. 2011a;
Wang et al. 2011; Weber et al. 2011a, 2011b). Consequently,
Petrocodon, the oldest valid generic name with its type
contained within the clade, was expanded to include all taxa
of the clade (Wang et al. 2011; Weber et al. 2011a), thus
echoing recent molecular-based redelimitation of genera of the
Old World Didymocarpoid Gesneriaceae such as Oreocharis
Benth. (Mo
¨
ller et al. 2011b; Liu et al. 2012) and Primulina
Hance (Wang et al. 2011; Weber et al. 2011b; Xu et al. 2012b).
The redelimitation of Petrocodon greatly increased the
extent of morphological variability in the genus. For exam-
ple, the color of the corolla under the new concept can be
white [Petrocodon s. s. and Tengia], white to pale-purple
(Didymocarpus), white to purple (Lagarosolen), purple
(Dolicholoma and Wentsaiboea), blue-purple (Paralagarosolen),
or bright red (Calcareoboea), while the diversity of corolla
shapes includes urceolate (Petrocodon s. s.), near-urceolate
(Tengia), cylindric (Lagarosolen), funnel-form or salver-shaped
(Didymocarpus), campanulate (Wentsaiboea), long open-
tubular (Calcareoboea), and narrow-tubular (Dolicholoma and
Paralagarosolen). The presence of these diverse corolla mor-
phologies in the redefined Petrocodon suggests a high degree
of evolutionary lability, presumably driven by adaptation to
different pollinators (Weber et al. 2011a).
In the course of floristic surveys of limestone areas of
Guangxi during the period 20062012, we collected three
additional, previously undocumented species that are mor-
phologically most closely allied to the species of Petrocodon
formerly included in Lagarosolen (Wang et al. 1998; Wei 2010).
After consulting relevant literature (Wang et al. 1998;
Wei 2006, 2007, 2010; Wei et al. 2008; Xu et al. 2008, 2010;
Jiang et al. 2011; Weber et al. 2011a; Wen et al. 2012) and
performing molecular phylogenetic analyses, we concluded
that the three new species were each assignable to the
expanded concept of Petrocodon (Weber et al. 2011a).
Here, we describe and illustrate these three new species
and make a new combination in Petrocodon for a fourth species,
Primulina guangxiensis Yan Liu & W. B. Xu (Liu et al. 2011),
which is nested within the expanded concept of Petrocodon in
our phylogenetic analyses. We also present and discuss the
morphological and molecular phylogenetic evidence upon
which our taxonomic conclusions are based.
Materials and Methods
Materials Examined—Morphological characters of the new species
were observed and measured in the field and/or from herbarium speci-
mens. For molecular data, DNA was extracted from silica-gel dried leaves
collected from the respective type localities. All voucher specimens are
deposited in IBK.
Molecular Methods—DNA sequences of nuclear internal transcribed
spacers (ITS) and chloroplast trnL-F intron-spacer region (trnL-F ) were
collected, as these two regions were employed to recircumscribe
Petrocodon (Weber et al. 2011a) and have been used routinely in recent
taxonomic and phylogenetic analyses of Old World Gesneriaceae (e.g.
Li and Wang 2007; Mo
¨
ller et al. 2011a, 2011b; Wang et al. 2011; Weber
et al. 2011a, 2011b; Xu et al. 2012a, 2012b, 2013; Chung et al. 2013). Proto-
cols for DNA extraction, PCR amplification, and sequencing were adopted
from Xu et al. (2012a).
To determine the phylogenetic affinities of the three new species and
Primulina guangxiensis, a DNA sequence matrix was assembled following
the sampling schemes of Xu et al. (2012a) for Primulina and Weber et al.
(2011a) for Petrocodon. The species Petrocodon jasminiflorus (D. Fang &
W. T. Wang) A. Weber & Mich. Mo
¨
ller and P. fangianus (Y. G. Wei)
Yin Z. Wang, although included in the study of Weber et al. (2011a), were
not sampled here because sequences were not available in GenBank.
Briggsia longipes (Hemsl. ex Oliv.) Craib, Briggsiopsis delavayi (Franch.)
K. Y. Pan, Hemiboea ovalifolia (W. T. Wang) A. Weber & Mich. Mo
¨
ller,
Hemiboea purpureotincta (W. T. Wang) A. Weber & Mich. Mo
¨
ller,
Loxostigma griffithii (Wight) C. B. Clarke, Lysionotus pauciflorus Maxim., and
Petrocosmea kerrii Craib were chosen as outgroup based on the results of
Mo
¨
ller et al. (2011a). The final matrix contained 41 ingroup taxa
(Petrocodon and Primulina) and an outgroup composed of representatives
from seven lineages. Appendix 1 lists all taxa sampled and corresponding
GenBank DNA sequence accession numbers.
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DNA sequences were aligned using the program MUSCLE imple-
mented in the software MEGA5 (Tamura et al. 2011) with minor manual
adjustments. The aligned matrix (TreeBASE study number TB2:S14036) was
analyzed using maximum parsimony (MP) and maximum likelihood (ML)
optimality criteria. Maximum p arsimony analyses including all alignment
positions were performed in MEGA5 using close-neighbor-interchange
(CNI) and 200 random addition replicates. Clade support was estimated
with 1,000 bootstrap replicates employing tree-bisection-reconnection
(TBR). For ML analysis, the matrix was partitioned (ITS vs. trnL-F). Ten
independent ML analyses were conducted using RAxML (Stamatakis et al.
2008) via RAxML BlackBox (http://phylobench.vital-it.ch/raxml-bb/),
with the gamma model of rate heterogeneity and the proportion of invari-
able sites for each of the two data partitions estimated by the program.
Results
Morphological Affinities—The three new species are mor-
phologically most similar to Petrocodon coriaceifolius (Y. G. Wei)
Y. G. Wei & Mich. Mo
¨
ller, differing by the texture, size, and
shape of the leaves, the structure of the inflorescence, the size
of the corolla, the density of the pubescence on the corolla, the
shape of the anthers, and the length of the pistil (Table 1).
Molecular Data—The DNA matrix includes 1,460 aligned
positions (ITS: 730 bp; trnL-F: 730 bp), of which 527 (ITS: 407 bp;
trnL-F: 120 bp) are variable and 300 (ITS: 257 bp; trnL-F:43bp)
are parsimony informative. The best ML tree (log likelihood
score = 9,167.793716) of the ten runs of RAxML analyses is
depicted in Fig. 1A and is also deposited as a tree file attached
to the aligned data matrix in TreeBASE. Maximum parsimony
analyses resulted in 14 equally most parsimonious trees of
1,337 steps (CI = 0.59, RI = 0.69, RCI = 0.41). The 50% majority
rule consensus cladogram was largely compatible with the
best ML tree (Fig. 1A).
All three new species display substantial divergences from
their respective sister species, as indicated by their relatively
long terminal branches (Fig. 1A), thus supporting their indi-
vidual recognition as distinct species. In both ML and MP
analyses (Fig. 1A), the three new species and Primulina
guangxiensis are placed in Petrocodon with strong support
(LB = 96; PB = 82). With the exclusion of Pri. guangxiensis,
Primulina is monophyletic, forming the sister group to
Petrocodon with strong support (LB = 100; PB = 99). Within
Primulina, phylogenetic relationships are highly congruent
with previous analyses (Xu et al. 2012a). Within Petrocodon,
the three new species and Pri. guangxiensis are placed in a
strongly supported but internally poorly resolved clade
(Fig. 1A; LB = 98; PB = 94) that also includes P. hancei
(Hemsl.) A. Weber & Mich. Mo
¨
ller, P. hechiensis (Y. G. Wei,
Yan Liu & F. Wen) Y. G. Wei & Mich. Mo
¨
ller, P. coccineus
(C. Y. Wu ex H. W. Li) Yin Z. Wang, P. ferrugineus Y. G. Wei,
P. coriaceifolius, P. scopulorum (Chun) Yin Z. Wang, P. dealbatus
Hance, and Lagarosolen ainsliifolius W. H. Chen & Y. M. Shui,
nom. nud., which was described and illustrated in Shui and
Chen (2006) and Wei (2010) but not validly published. These
same taxa minus Pri. guangxiensis and the three new species
were similarly grouped in a strongly supported clade with
low internal resolution in the analysis of Weber et al. (2011a).
Interestingly, although the three new species are morphologi-
cally most similar to P. coriaceifolius, none of them appears to
be its sister taxon (Fig. 1A).
Discussion
Based on the results of their phylogenetic study, Weber et al.
(2011a) hypothesized that the current species diversity of
Petrocodon evolved during three episodes of species radiation.
Our results suggest that the four newly added species origi-
nated during the second episode (Fig. 1A). The addition of
these four species to the phylogeny of Petrocodon does not
substantially alter the basic structure recovered by Weber
et al. (2011a).
The discovery of three morphologically (Table 1) and
molecularly (Fig. 1A) distinct species of Petrocodon, plus the
transfer of Primulina guangxiensis to Petrocodon, increases to
23 the number of species included in Petrocodon. Given the
diversity of floral morphologies that exist within the genus
(Fig. 1B), as well as its moderate number of species,
Petrocodon is a promising model for investigating trends in
floral evolution that may be important in other Old World
Didymocarpoid Gesneriaceae. Although phylogenetic sam-
pling is incomplete, our results suggest that salver-shaped to
cylindric corollas (i.e. species formerly included in Lagarosolen)
may be ancestral in the genus (Fig. 1AB; Weber et al. 2011a),
with more specialized corolla shapes, such as urceolate, long-
salver-shaped, and open-tubular, probably having evolved
later (Fig. 1B; Weber et al. 2011a). Additional field observa-
tions are needed to determine the extent to which evolution-
ary transformations in corolla morphology are correlated with
pollinator shifts and to test competing hypothesis about how
such shifts may have affected speciation.
Taxonomic Treatment
1. Petrocodon guangxiensis (Yan Liu & W. B. Xu) W. B. Xu &
K. F. Chung, comb. nov. Primulina guangxiensis Yan
Liu & W. B. Xu in Liu et al. Nordic J. Bot. 29: 682. 2012
Table 1. Morphological comparisons of Petrocodon coriaceifolius, P. laxicymosus, P. longgangensis,andP. pseudocoriaeifolius.
Characters P. coriaceifolius P. laxicymosus P. longgangensis P. pseudocoriaeifolius
Leaf texture Coriaceous Coriaceous Chartaceous Coriaceous
Leaf blade shape Ovate-elliptic to ovate-oblong Elliptic Ovate or broadly ovate to elliptic Oblong
Leaf blade size 2.58
+
1.74.5 cm 25
+
1.52.3 cm 715
+
48.5 cm 1018
+
4–6 cm
Leaf apex Obtuse to rounded Acute to obtuse Obtuse or acute Acute to obtuse
Leaf margin Entire Repand to entire Serrate Serrate
Leaf base Shallowly cordate Cuneate Cuneate, round to shallowly cordate Cuneate
Cymes 13-branched 1- or 2-branched 13-branched 2- or 3-branched
Number of flowers 714 15 1015 1025
Corolla length 1830 mm 2030 mm 1012 mm 2025 mm
Corolla surface Pubescent Glabrous to sparsely pubescent Brown hispidulous Purple pubescent
Anthers Reniform Reniform Reniform Elliptic
Pistil length ca. 16 mm 1620 mm 58.5 mm 1319 mm
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("2011").—TYPE: CHINA. Guangxi: Fengshan County,
Paoli Town, on moist limestone rock face in a karst cave,
17 Apr 2009 (fl), Wei-Bin Xu and Yan Liu 09352 (holotype:
IBK!; isotype: PE!).
2. Petrocodon laxicymosus W. B. Xu & Yan Liu, sp. nov.—
TYPE: CHINA. Guangxi: Jingxi County, Ande Town,
growing in evergreen broad-leaved forest on slopes of
limestone hills, alt. 1,100 m, 16 Aug 2009 (fl), Wen-Bin Xu
et al. 09993 (holotype: IBK).
Herbs, perennial. Rhizome subterete, 29 cm
+
2.54 mm.
Leaves 515, basal; petiole 1.54.5 cm, terete, canaliculated
adaxially, puberulous; leaf blade coriaceous, elliptic, 25
+
1.52.3 cm, the apex acute to obtuse, the margin repand to
entire, sometimes serrate, the base cuneate, slightly oblique,
with appressed pubescence on both sides; lateral veins 35 on
each side of central vein, depressed adaxially, prominent
abaxially. Cymes 35, axillary, 1- or 2-branched, 15-flowered;
peduncle 514 cm
+
12 mm, sparsely puberulous; bracts 2,
opposite, linear-lanceolate, 68
+
11.5 mm, the margin
entire, the apex acute, pubescent abaxially; bracteoles 2,
opposite, linear, puberulous abaxially. Pedicel 510 mm long,
puberulous. Calyx 5-lobed nearly to base, the lobes narrowly
lanceolate to linear, 35
+
0.5 mm, the margin entire,
puberulous externally, glabrous internally. Corolla purple,
salver-shaped, 2030 mm long, glabrous to sparsely pubes-
cent externally, glabrous internally; tube slender, 1220 mm
long, 46 mm in diam. at mouth, ca. 3 mm in diam. at base;
limb distinctly 2-lipped, the upper lip ca. 4 mm long, 2-lobed
to near base, the lobes broadly ovate, ca. 4
+
4 mm, the lower
lip ca. 810 mm long, 3-lobed to near the middle, the lobes
broadly ovate, ca. 4
+
6 mm. Stamens 2, adnate to ca. 1.2 cm
above corolla tube base; filaments erect, 68 mm long, linear,
puberulent; anthers reniform, ca. 3 mm long, dorsifixed, the
thecae confluent at apex. Staminodes 3, glabrous, adnate
to ca. 79 mm above corolla tube base, the lateral ones ca.
2.5 mm long, the middle one 1 mm long. Disc orbicular,
ca. 0.5 mm high, the margin repand. Pistil 1620 mm long,
ovary 8–10
+
ca. 1.5 mm, puberulent; style 810 mm long,
puberulent; stigmas 2, broadly ovate, ca. 1 mm, equilateral.
Capsule linear, 24 cm
+
ca. 2 mm, 4-valved. Figures 2AB, 3.
Paratypes—CHINA. Guangxi: Jingxi County, Ande Town,
alt. 1,100 m, 29 May 2009, Wei-Bin Xu et al. 09662 (IBK); same
locality, 16 Aug 2009, Wei-Bin Xu et al. 09988 (IBK); same
locality, 23 Mar 2012, Yu-Song Huang et al. Y1059 (IBK);
same locality, 15 Apr 2012, Yu-Song Huang Y1230 (IBK).
Jingxi County, Wuping Town, alt. 600 m, 16 Aug 2008, Wei-
Bin Xu 08187 (IBK); the same locality, 7 Jul 2009, Wei-Bin Xu &
Bo Pan 09689 (IBK).
Phenology—The species is flowering from July to August
and fruiting August to October.
Fig. 1. A. The best-scoring ML tree from one of the ten analyses of ITS and trnL-F sequence data. Phylogenetic placements of Petrocodon laxicymosus,
P. longgangensis, P. pseudocoriaceifolius,andPrimulina guangxiensis are highlighted. Bootstrap values (LB/PB) greater than 50% are shown. Thick lines
denote a strongly supported clade with LB and/or PB greater than 95%. Dashed lines indicate clades collapsed in the majority rule consensus tree of
MP analyses. B. Character states of Petrocodon clade modified from Fig. 1 of Weber et al. (2011a). Stam.: number of fertile stamens (a, anterior pair); 4v,
dehiscing into 4 valves. C. Geographic distributions of P. laxicymosus (triangle), P. longgangensis (square), P. pseudocoriaceifolius (circle), and P. guangxiensis (star).
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Fig. 2. Photographs of the new species. A, B. Petrocodon laxicymosus.C,D.Petrocodon longgangensis.E,F.Petrocodon pseudocoriaceifolius.
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Fig. 3. Petrocodon laxicymosus W. B. Xu & Yan Liu (Drawn by W.-H. Lin based on holotype). A. Habit. B. Corolla opened, showing stamens
and staminodes. C. Stamens. D. Calyx and pistil. E. Stigma. F. Capsule.
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Etymology—The specific epithet refers to the sparse
arrangement of the cymes.
Distribution and Ecology—Petrocodon laxicymosus is known
only from the type locality in Jingxi County, Guangxi (Fig. 1C),
with fewer than 250 mature individuals. It grows in ever-
green broad-leaved forest on slopes of limestone hills, at
6001,100 m elevation.
Notes—Petrocodon laxicymosus is similar to P. coriaceifolius
but differs in the shape (elliptic vs. ovate-elliptic to ovate-
oblong) and size (25
+
1.52.3 cm vs. 2.58.5
+
1.74.5
cm) of the leaf blade, the shape of the leaf apex (acute to
obtuse vs. obtuse to rounded) and base (cuneate vs. shal-
lowly cordate), the form of the leaf margin (repand to entire
or occasionally serrate vs. always entire), the branching of the
cymes (1 or 2-branched vs. 13-branched), and the number of
flowers per cyme (15 vs. 714).
3. Petrocodon longgangensis W. H. Wu & W. B. Xu, sp. nov.—
TYPE: CHINA. Guangxi: Longzhou County, Nonggang
National Nature Reserve, growing in evergreen broad-
leaved forest on slopes of limestone hills, alt. 400 m,
27 Oct 2010 (fl), Wang-Hui Wu W0285 (holotype: IBK;
isotypes: PE, IBK).
Herbs, perennial. Rhizome subterete, 1.53.5 cm
+
4–8 mm.
Leaves 516, basal; petiole 2.55 cm, terete, canaliculated
adaxially, brown hispid; leaf blade chartaceous, ovate or
broadly ovate to elliptic, 715
+
48.5 cm, the apex obtuse
or acute, the margin serrate, the base cuneate, round to shal-
lowly cordate, slightly oblique, appressed hirtellous on both
sides; lateral veins 58 on each side of central vein, depressed
adaxially, prominent abaxially. Cymes 25, axillary, 13-
branched, 1015-flowered; peduncle 510.5 cm
+
ca. 2.5 mm,
brown hispid; bracts 2, opposite, linear-lanceolate, 69
+
1.5 mm, margin entire, apex acuminate, brown hispidulous;
bracteoles 2, opposite, linear, 36 mm long. Pedicel ca. 3.5 mm,
brown hispidulous. Calyx 5-lobed nearly to the base, the lobes
narrowly lanceolate to linear, ca. 2
+
0.5 mm, the margin
entire, brown hispidulous externally, sparsely puberulent
internally. Corolla purple, salver-shaped, 1012 mm long,
brown hispidulous externally, sparsely puberulent internally;
tube slender, 89 mm long, ca. 3.5 mm in diam. at mouth, ca.
2.5 mm in diam. at base; limb distinctly 2-lipped, the upper lip
ca. 2.5 mm long, 2-lobed to near base, the lobes ovate, ca. 2
+
1.5 mm; the lower lip ca. 4 mm long, 3-lobed to above the
middle, the lobes ovate, ca. 3
+
2 mm. Stamens 2, adnate to ca.
4mmabovecorollatubebase;filamentserect,ca.5mmlong,
linear, puberulent; anthers reniform, black, ca. 1 mm long,
dorsifixed, thecae confluent at apex. Staminodes 3, glabrous, the
apex capitate, adnate to ca. 3.5 mm above corolla tube base,
thelateralonesca.1.5mm,themiddleone1.4mm.Disc
semiorbicular, ca. 1 mm high, the margin repand. Pistil 5
8.5 mm long, ovary 35.5 mm long, ca. 1 mm in diam., puber-
ulent; style 23 mm long, puberulent; stigmas 2, broadly ovate,
ca.0.4mm,bifid.Capsulelinear,34.5cmlong,ca.1mmin
diam., 4-valved. Figures 2CD, 4.
Phenology—The species is flowering from October to
November and fruiting November to December.
Etymology—The specific epithet refers to the vernacular
pronunciation (Longgang) of the type locality, Nonggang
National Natural Reserve.
Distribution and Ecology—Petrocodon longgangensis is cur-
rently known only from one population with less than 250
mature individuals in Nonggang National Nature Reserve
(Fig. 1C). It grows in evergreen broad-leaved forest on slopes
of limestone hills, at 300400 m elevation.
Notes—Petrocodon longgangensis is similar to P. laxicymosus
but differs in the texture (chartaceous vs. coriaceous), the
shape (ovate or broadly ovate to elliptic vs. elliptic) and the
size (715
+
48.5 cm vs. 25
+
1.52.3 cm) of the leaf blade,
the shape of leaf apex (obtuse or acute vs. acute to obtuse)
and base (cuneate, round to shallowly cordate vs. cuneate),
and the form of margin (serrate vs. repand to entire or some-
times serrate), the branching of the cymes (13-branched and
1015-flowered vs. 1- or 2-branched and 15-flowered), the
size (1012 mm vs. 23 cm long) and the pubescence (brown
hispidulous vs. glabrous to sparsely pubescent externally) of
corolla, and the length of pistil (58.5 vs. 1620 mm).
4. Petrocodon pseudocoriaceifolius Yan Liu & W. B. Xu, sp.
nov.—TYPE: CHINA. Guangxi: Luocheng County,
Huaiqun Town, growing in evergreen broad-leaved for-
est on slopes of limestone hills, alt. 320 m, 19 Apr 2009
(fl), Wei-Bin Xu & Yan Liu 09412 (holotype: IBK; isotypes:
PE, IBK).
Herbs, perennial. Rhizome subterete, 18 cm
+
412 mm
across. Leaves 612, basal; petiole 24 cm long, terete,
canaliculated adaxially, purple puberulent; leaf blade coria-
ceous, oblong, 1018
+
46 cm, the apex acute to obtuse, the
margin serrate, the base cuneate, slightly oblique, with
appressed purple pubescence on both sides; lateral veins
58 on each side of central vein, depressed adaxially and prom-
inent abaxially. Cymes 24, axillary, 2- or 3-branched, 10
25-flowered; peduncle 514 cm long, ca. 3 mm across, with
appressed purple pubescence; bracts 2, opposite, linear-
lanceolate, 1017
+
1.53 mm, margin entire, apex acute,
purple pubescent externally; bracteoles 2, opposite, linear,
7–10
+
11.5 mm, purple pubescent externally. Pedicel 4
8 mm long, purple pubescent. Calyx 5-lobed nearly to base,
the lobes narrowly lanceolate to linear, 2.54
+
0.5 mm,
margin entire, purple pubescent externally, glabrous inter-
nally. Corolla pale purple, salver-shaped, 2025 mm long,
purple pubescent externally, sparsely puberulent internally;
tube slender, 1216 mm long, 44.5 mm in diam. at mouth,
ca. 3 mm in diam. at base; limb distinctly 2-lipped, upper lip
ca. 3 mm long, 2-lobed to near base, the lobes ovate, ca. 3
+
3 mm; lower lip ca. 810 mm long, 3-lobed to above middle,
the lobes ovate, ca. 3 mm
+
3 mm. Stamens 2, adnate to 8
9 mm above corolla tube base; filaments erect, 57 mm long,
linear, purple puberulent; anthers elliptic, ca. 1.5 mm long,
dorsifixed, thecae confluent at apex. Staminodes 3, gla-
brous, the apex capitate, adnate to ca. 57 mm above corolla
tube base, lateral ones ca. 1.5 mm long, middle one 0.5 mm
long. Disc orbicular, ca. 1.2 mm high, the margin repand. Pistil
1319 mm long, ovary 68 mm long, ca. 1.2 mm across, purple
puberulent; style 610 mm long, purple puberulent; stigmas 2,
broadly ovate, ca. 0.5 mm, equilateral. Capsule not seen.
Figures 2EF, 5.
Paratypes—CHINA. Guangxi: Luocheng County, Huaiqun
Town, alt. 320 m, 5 May 2006, Wei-Bin Xu & Yan Liu 06046
(IBK). Huanjiang County, Mulun National Nature Reserve,
alt. 575 m, 29 Apr 2011, Yu-Song Huang et al. Y0119 (IBK); the
same locality, 2 May 2011, Yu-Song Huang et al. Y0201 (IBK);
the same locality, 12 May 2011, Wei-Bin Xu 11152 (IBK).
Phenology—The species is flowering from April to May.
Etymology—The specific epithet refers to its resemblance
to P. coriaceifolius.
970 SYSTEMATIC BOTANY [Volume 39
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Copyright (c) American Society for Plant Taxonomists. All rights reserved.
Fig. 4. Petrocodon longgangensis W. H. Wu & W. B. Xu (Drawn by Y.-X. Zhu based on holotype). A. Habit. B. Corolla opened, showing stamens
and staminodes. C. Stamens. D. Calyx and pistil. E. Stigma.
2014] XU ET AL.: PETROCODON SPECIES AND COMBINATION NOVA OF GUANGXI, CHINA 971
Delivered by Publishing Technology to: Kuo-Fang Chung IP: 140.112.82.51 on: Tue, 01 Jul 2014 06:49:32
Copyright (c) American Society for Plant Taxonomists. All rights reserved.
Fig. 5. Petrocodon pseudocoriaceifolius Yan Liu & W. B. Xu (Drawn by S.-Q. He based on holotype). A. Habit. B. Flower. C. Corolla opened, showing
stamens and staminodes. D. Stamens. E. Calyx and pistil. F. Stigma.
972 SYSTEMATIC BOTANY [Volume 39
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Copyright (c) American Society for Plant Taxonomists. All rights reserved.
Distribution and Ecology—Petrocodon pseudocoriaceifolius is
known from the type locality in Luocheng County and Mulun
National Nature Reserve in Huanjiang County, Guangxi
(Fig. 1C). It grows in evergreen broad-leaved forests on
slopes of limestone hills, at 300600 m elevation.
Notes—Petrocodon pseudocoriaceifolius is similar to
P. coriaceifolius but differs in the shape (oblong vs. ovate-
elliptic to ovate-oblong) and size (1018
+
46 cm vs. 2.5
8.5
+
1.74.5 cm) of the leaf blade, the shape of the leaf apex
(acute to obtuse vs. obtuse to rounded), margin (serrate vs.
entire), and base (cuneate vs. shallowly cordate), and the
shape of anthers (elliptic vs. reniform).
Acknowledgments. The authors are grateful to Prof. Fa-Nan Wei
(IBK) for his help in preparing the paper, to Mr. Shun-Qing He (IBK),
Wen-Hong Lin (IBK), and Yun-Xi Zhu (IBK) for skillfully illustrating the
new species, and Dr. Benjamin M. Torke for improving the manuscript.
This study was supported by the National Natural Science Foundation of
China (Grant no. 41161011) to Yan Liu, a National Geographic Society
Grant # 8358-07 to Ching-I Peng, Yan Liu, and Kuo-Fang Chung, and a
grant from the National Science Council, Taiwan (NSC 99-2621-B-001-
001-MY3) to Ching-I Peng and Kuo-Fang Chung.
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Appendix 1. Taxon and GenBank accession numbers. Species: (ITS/
trnL-F). All newly acquired sequences were derived from type collection.
Briggsia longipes (Hemsl. ex Oliv.) Craib: GU350653/FJ501545;
Briggsiopsis delavayi (Franch.) K. Y. Pan: GU350647/HQ632879;
Hemiboea ovalifolia (W. T. Wang) A. Weber & Mich. Mo
¨
ller: HQ632980/
HQ632883; Hemiboea purpureotincta (W. T. Wang) A. Weber & Mich.
Mo
¨
ller: HQ632981/HQ632884; Lagarosolen ainsliifolius W. H. Chen &
Y. M. Shui, nom. nud.: HQ633038/HQ632941; Loxostigma griffithii
(Wight) C. B. Clarke: FJ501338/FJ501508; Lysionotus pauciflorus Maxim.:
FJ501331/FJ501497; Petrocodon coccineus (C. Y. Wu ex H.W. Li) Yin Z.
Wang: FJ501365/FJ501516; Petrocodon coriaceifolius (Y. G. Wei) Y. G.
Wei & Mich. Mo
¨
ller: HQ633040/HQ632943; Petrocodon dealbatus
Hance: FJ501358/FJ501537; Petrocodon dealbatus var. denticulatus
(W. T. Wang) W. T. Wang: JF697578/JF697590; Petrocodon ferrugineus
Y. G. Wei: HQ633043/HQ632946; Petrocodon guangxiensis (Yan Liu &
W. B. Xu) W. B. Xu & K. F. Chung: JX506899/JX506791; Petrocodon
hancei (Hemsl.) A. Weber & Mich. Mo
¨
ller: HQ633041/HQ632944;
Petrocodon hechiensis (Y. G. Wei, Yan Liu & F. Wen) Y. G. Wei & Mich.
Mo
¨
ller: HQ633039/HQ632942; Petrocodon hispidus (W. T. Wang) A.
Weber & Mich. Mo
¨
ller: HQ633036/ HQ632939; Petrocodon integrifolius
(D. Fang & L. Zeng) A. Weber & Mich. Mo
¨
ller: HQ633037/HQ632940;
Petrocodon laxicymosus W. B. Xu & Yan Liu: KC765115/KC765117;
Petrocodon lui (Yan Liu & W. B. Xu) A. Weber & Mich. Mo
¨
ller:
HQ633035/ HQ632938; Petrocodon niveolanosus (D. Fang & W. T.
Wang) A. Weber & Mich. Mo
¨
ller: JF697576/JF697588; Petrocodon
longgangensis W. H. Wu & W. B. Xu: KC765114/KC765116; Petrocodon
pseudocoriaceifolius Yan Liu & W. B. Xu: JX506852/JX506741;
Petrocodon scopulorum (Chun) Yin Z. Wang: GU350637/GU350669;
Petrocodon tiandengensis (Yan Liu & B. Pan) A. Weber & Mich. Mo
¨
ller:
HQ633042/HQ632945; Petrocosmea kerrii Craib: FJ501334/FJ501502;
Primulina bipinnatifida (W. T. Wang) Yin Z. Wang: DQ872842/
DQ872806; Primulina cordifolia (D. Fang & W. T. Wang) Yin Z. Wang:
DQ872845/DQ872803; Primulina dryas (Dunn) Mich. Mo
¨
ller & A. Weber:
FJ501348/ FJ501524; Primulina gemella (D. Wood) Yin Z. Wang:
FJ501345/FJ501523; Primulina glandulosa (D. Fang, L. Zeng & D. H.
Qin) Yin Z. Wang: DQ872841/DQ872804; Primulina heterotricha (Merr.)
Yin Z. Wang: (DQ872826/DQ872816); Primulina linearifolia (W. T.
Wang) Yin Z. Wang: DQ872834/DQ872810; Primulina longgangensis
(W. T. Wang) Yin Z. Wang: FJ501347/AJ492290; Primulina luochengensis
(Yan Liu & W. B. Xu) Mich. Mo
¨
ller & A. Weber: HQ633046/HQ632949;
Primulina minutimaculata (D. Fang & W. T. Wang) Yin Z. Wang:
DQ872828/DQ872815; Primulina mollifolia (D. Fang & W. T. Wang)
Yin Z. Wang: JX506866/JX506755; Primulina multifida B. Pan & K. F.
Chung: JX507031/JX506756; Primulina ophiopogoides (D. Fang & W. T.
2014] XU ET AL.: PETROCODON SPECIES AND COMBINATION NOVA OF GUANGXI, CHINA 973
Delivered by Publishing Technology to: Kuo-Fang Chung IP: 140.112.82.51 on: Tue, 01 Jul 2014 06:49:32
Copyright (c) American Society for Plant Taxonomists. All rights reserved.
Wang) Yin Z. Wang: DQ872829/DQ872814; Primulina pinnatifida
(Hand.-Mazz.) Yin Z. Wang: FJ501350/FJ501527; Primulina
pseudomollifolia W. B. Xu & Yan Liu: JX506869/JX506759; Primulina
pteropoda (W. T. Wang) Yan Liu: DQ872827/DQ872817;
Primulina renifolia (D. Fang & D. H. Qin) Yin Z. Wang: JX506737/
JX506851; Primulina repanda var. guilinensis (W. T. Wang) Mich.
Mo
¨
ller & A. Weber: DQ872846/DQ872808; Primulina spadiciformis
(W. T. Wang) Mich. Mo
¨
ller & A. Weber: FJ501346/AJ492291; Primulina
spinulosa (D. Fang & W. T. Wang) Yin Z. Wang: DQ872830/DQ872813;
Primulina tabacum Hance: FJ501352/AJ492300; Primulina weii Mich.
Mo
¨
ller & A. Weber: DQ872832/ DQ872811; Primulina wentsaii (D. Fang &
L. Zeng) Yin Z. Wang: DQ872831/DQ872812.
974 SYSTEMATIC BOTANY [Volume 39
... During our fieldwork in Leping County (Jiangxi Province) in 2017, we found an unknown species of Gesneriaceae with a small, pale purple to white corolla and exsert pistil. We examined specimens deposited at IBK, KUN, ANU, PE, consulted local and national floras, and relevant literature including recently published papers describing new species with small flowers, purple corolla and exsert pistil (e.g., Wang et al. 1990, 1998, Li & Wang 2004, Wei et al. 2010, Xu et al. 2014, 2017, Zhang et al. 2018. As a result, we were able to confirm we had a new species at hand, which is closely related to P. asterocalyx. ...
... To test the systematic placement of the new species, the nuclear ribosome internal transcribed spacers (ITS) region and chloroplast trnL-F intron spacer (trnL-F) were chosen to reconstruct the phylogenetic tree of Petrocodon, since these two regions were frequently used in previous taxonomic and phylogenetic works of (e.g. Möller et al. 2009, 2011, Chen et al. 2014, Xu et al. 2014, Yu et al. 2015, Lu et al. 2017a, 2017b, Zhang et al. 2018, 2019. We extracted total genomic DNA of the new species and Petrocodon hunanensis from silica-dried leaves collected from the field using a CTAB method (cf. ...
... Soon afterwards, the genus was redefined based on molecular phylogenetic studies. The small Chinese genus Petrocodon has been recently enlarged to include four former monotypic genera ( (Weber et al. 2011) and one species of Primulina Hance (Xu et al. 2014). Thus, Petrocodon s.l. ...
... Zhang, 2017a, P. urceolatus F.Wen, H.F. Cen & L.F. Fu, 2017, P. retroflexus Q. Zhang & J. Guo, 2016, and so on. Obviously, the genus is so special on account of its remarkable and highly variable floral structures that it also becomes one of the most taxonomically difficult groups in Gesneriaceae (Möller et al. 2016, Lu et al. 2017b (Liu et al. 2011, Xu et al. 2014 while it was published. On the other hand, similar characters of leaves sometimes affect our judgement of some Petrocodon congeners. ...
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A new species of Gesneriaceae, Petrocodon luteoflorusLei Cai & F.Wen was first described and illustrated from Maolan National Nature Reserve, Libo County, Guizhou Province, China. The diagnostic characters and notes of this species between its most morphologically similar species, P. dealbatusHance, a detailed description, colour photographs, etymology, as well as distribution and habitat, are also provided in this paper.
... Molecular phylogenetic research on Gesneriaceae over the last two decades has greatly advanced our understanding of species relationships and generic delimitations (Möller et al. 2011). Petrocodon Hance (1883: 167) was once treated as a genus of three species and one variety (Jiang et al. 2011, Wei 2006, but several genera have been merged within it based on recent molecular studies (Wang et al. 2010, Möller et al. 2011, Weber et al. 2011a, 2011b, Xu et al. 2014. This circumscription of Petrocodon has resulted in increased morphological variation within the genus (Weber et al. 2011a). ...
... However, all the plants were rosulate and stemless, different from the caulescent P. hunanensis. We concluded that these plants represent an undescribed species in Petrocodon based on morphological and molecular data and a search through relevant literature (Wang 1984, Wei 2006, Wei et al. 2010, Jiang et al. 2011, Weber et al. 2011a, Wen et al. 2012, Chen et al. 2014, Hong et al. 2014, Xu et al. 2014, Yu et al. 2015. Molecular evidence indicates that this new species, hereafter named P. longitubus Cong R.Li & Yang Luo, is sister to P. hunanensis. ...
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Petrocodon longitubus, a new species of Gesneriaceae from Guizhou province, China, is described and illustrated. It is similar to P. hunanensis in having four stamens, but readily differs in being rosulate and stemless and having a narrowly infundibuliform floral tube with the adaxial lip bending upward. Molecular evidence indicates that it is sister to P. hunanensis, but the two species differ markedly in morphology.
... Although the newly delimitation Petrocodon Hance is not the most speciose genus in Gesneriaceae of China, the highly variable corolla and leaf morphology impels us to continuously study and understand the species biodiversity of this genus (Lu et al. 2017. Now, approximately 35 species and one variety range from China to northern Thailand and northern Vietnam , Chen et al. 2014, Xu et al. 2014, Middleton et al. 2015, 2013, 2016. ...
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Petrocodon rubiginosus Y.G. Wei & R.L. Zhang, sp. nov., from Guangxi of South China, is described and illustrated with photographs. The new species is morphologically similar to Pet. hechiensis, but can be easily distinguished by a combination of characters, especially in its petioles, peduncles and pedicels covered with densely ferruginous pilose hairs.
... After consulting the monographs Wang 2005, Wei et al. 2010) and comparing the species with all other congeners described (i.e. Chen et al. 2014, Chen et al. 2019, Xu et al. 2014, Hong et al. 2014, Guo et al. 2016, Cen et al. 2017, Lu et al. 2017b, Zhang et al. 2018, Li et al. 2019) and specimens of Gesneriaceae deposited at IBSC, IBK, KUN, PE, US and VMN. We confirmed that it is a new species and hence we describe and illustrate it below as such. ...
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A new species of Petrocodon, P. wenshanensis from Yunnan province of southwestern China, is described and illustrated here. P. wenshanensis morphologically closely resembles P. jingxiensis and P. lithophilus, but differs in vegetative and generative characters. Differences between the new species and others Petrocodon species occurring in Yunnan Province are also shown in the identification key.
... Although the newly delimitation Petrocodon Hance is not the most speciose genus in Gesneriaceae of China, the highly variable corolla and leaf morphology impels us to continuously study and understand the species biodiversity of this genus (Lu et al. 2017. Now, approximately 35 species and one variety range from China to northern Thailand and northern Vietnam , Chen et al. 2014, Xu et al. 2014, Middleton et al. 2015, 2013, 2016. ...
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Petrocodon rubiginosus , a new species from Guangxi of South China is described and illustrated with photographs. The new species is morphologically similar to Pet. hechiensis, but can be easily distinguished by a combination of characters, especially in its petioles, peduncles and pedicels covered with densely ferruginous pilose hairs.
... During an expedition in September 2016 investigating the karst flora of Guizhou, we collected a special Petrocodon species in flower from a single locality in Tongzi County, Guizhou, China. The species has four fertile stamens, clearly differentiating it from all described species of Petrocodon except P. hunanensis (Wang et al. 1990, 1998, Wei et al. 2010a, 2010b, Jiang et al. 2011, Liu et al. 2011, Weber et al. 2011, Wen et al. 2012, Hong et al. 2014, Chen et al. 2014, Xu et al. 2014, Li and Wang 2015, Yu et al. 2015, Guo et al. 2016, Cen et al. 2017, Lu et al. 2017. To further investigate the status of this special species and the phylogenetic relevance of the four fertile stamens, we undertook a careful comparison and employed molecular markers to reconstruct the phylogeny of the genus. ...
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Petrocodon tongziensis R.B.Zhang & F.Wen, a new species from northern Guizhou province, China, is described and illustrated based on molecular and morphological evidence. The new species was found growing in crevices and on tufa of moist surfaces of limestone hills in Tongzi County. A maximum parsimony (MP) analysis based on the combined ITS and trnL‐F DNA regions showed that the new species falls within a large polytomy within Petrocodon, but is resolved as most closely related to an unidentified species (WF2014) and these two taxa are in turn resolved as sister to Petrocodon hunanensis X.L.Yu & Ming Li. This is congruent with the fact that both P. hunanensis and P. tongziensis have four fertile stamens, a character state likely to be an ancestral state distinguishing this clade from the rest of Petrocodon. Petrocodon tongziensis differs from P. hunanensis by lacking a terrestrial stem, as well as by the number of bracts, presence of bracteoles, shape of the lobes of the upper lip, and reduced number and length of staminodes.
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