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A new definition of the genus Petrocodon (Gesneriaceae)

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  • Guangxi Institute of Botany, CAS

Abstract and Figures

Based on molecular studies, the small Chinese genus Petrocodon (two species and one variety) has been recently enlarged to include the monotypic genera Calcareoboea, Paralagarosolen and Tengia. It is shown here that the (6-7) species of Lagarosolen, the monotypic Dolicholoma, a few species of Didymocarpus, and a number of new species that have recently been published (but not formally described) under Petrocodon and Lagarosolen should be included in this genus. This raises the size of the genus from five to around 20 species. With respect to the floral diversity (corolla form, size, and coloration; with the exception of Tengia, the androecium is always diandrous) and inferred pollination syndromes (different forms of melittophily, ornithophily, psycho- and/or sphingophily), Petrocodon represents one of the most varied genera of Old World Gesneriaceae, comparable to some New World genera.
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Accepted by M. Weigend: 17 Apr. 2011; published: 16 May 2011 49
PHYTOTAXA
ISSN 1179-3155 (print edition)
ISSN 1179-3163 (online edition)
Copyright © 2011 Magnolia Press
Phytotaxa 23: 4967 (2011)
www.mapress.com/phytotaxa/Article
A new definition of the genus Petrocodon (Gesneriaceae)
ANTON WEBER1,4, YI-GANG WEI2, CARMEN PUGLISI3, FANG WEN2, VERONIKA MAYER1 &
MICHAEL MÖLLER3,4
1 Department of Structural and Functional Botany, Faculty of Biodiversity, University of Vienna, Austria
2 Guangxi Institute of Botany, Guangxi Zhuang Autonomous Region and the Chinese Academy of Sciences, Guilin 541006, China
3 Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, Scotland, U.K.
4 Authors for correspondence; e-mails: anton.weber@univie.ac.at, m.moeller@rbge.ac.uk
Abstract
Based on molecular studies, the small Chinese genus Petrocodon (two species and one variety) has been recently
enlarged to include the monotypic genera Calcareoboea, Paralagarosolen and Tengia. It is shown here that the (67)
species of Lagarosolen, the monotypic Dolicholoma, a few species of Didymocarpus, and a number of new species that
have recently been published (but not formally described) under Petrocodon and Lagarosolen should be included in this
genus. This raises the size of the genus from five to around 20 species. With respect to the floral diversity (corolla form,
size, and coloration; with the exception of Tengia, the androecium is always diandrous) and inferred pollination
syndromes (different forms of melittophily, ornithophily, psycho- and/or sphingophily), Petrocodon represents one of the
most varied genera of Old World Gesneriaceae, comparable to some New World genera.
Key words: Calcareoboea, Didymocarpus, Dolicholoma, Lamiales, Lagarosolen, molecular systematics,
Paralagarosolen, pollination syndromes, Tengia
Introduction
A recent molecular phylogenetic study (Möller et al. 2009) revealed that the Chinese genera Petrocodon
(three species with small, white, urceolate flowers, with buzz-pollination syndrome) and Calcareoboea
(monotypic in its original concept, with large, long-tubular, bright red, apparently ornithophilous flowers)
form a strongly supported clade. This was confirmed in the study of Wang et al. (2011) who also added
Paralagarosolen (with long-tubed hypocrateriform flowers) and Tengia (with flowers similar to Petrocodon,
but with five fertile stamens) to the clade and expanded the definition of Petrocodon to include these four
genera, with five species in total. The present paper provides molecular evidence that this definition is still too
narrow and that some more genera have to be included in Petrocodon. In addition, the new definition
demonstrates strikingly, and exemplarily for the Old World Gesneriaceae, how unreliable traditional generic
definitions, often based exclusively on floral characters, are. Petrocodon emerges as one of the florally most
diverse clades of Old World Gesneriaceae.
Material and Methods
Plant material
Leaf material for newly acquired sequences came from silica gel dried field collections. Most molecular data
came from previous work (Möller et al. 2009, 2011a, Weber et al. 2011), sequences for three taxa were
WEBER ET AL.50 Phytotaxa 23 © 2011 Magnolia Press
additionally acquired and for another three they came from GenBank (Table 1). A total of 31 samples was
included in the analyses, comprising 30 species (including 2 undescribed species) and 1 variety.
Based on previous work (Möller et al. 2009, 2011a, Weber et al. 2011) and an extended analysis on 259
didymocarpoid Gesneriaceae (data not shown), it was demonstrated that the Petrocodon clade was
monophyletic. Suitable outgroup samples for this clade were Lysionotus Don (1822: 85) (L. pauciflorus, L.
petelotti) and Loxostigma Clarke (1883: 59) (L. fimbrisepalum, L. griffithii) and the newly defined genus
Primulina Hance (1883: 169) (10 species, Wang et al. 2011, Weber et al. 2011). The trees were rooted on the
Lysionotus and Loxostigma samples (based on the data presented in Möller et al. 2009, 2011a, Weber et al.
2011).
TABLE 1: List of the 31 didymocarpoid Gesneriaceae samples included in the phylogenetic analysis, including voucher number and
deposition, origin information and respective GenBank accession numbers.
Taxon Voucher number Deposited
in Origin trnL-F ITS or
ITS1 / ITS2
Calcareoboea coccinea C.Y.Wu
ex H.W.Li (1982: 243) M.Möller MMO 01-141 E, WU China, Guangxi,
Napo county FJ501516 FJ501365
Chirita gemella D.Wood (1972:
370) L.Averyanov 1987 [Cult. RBGE
19941913] E Vietnam, Hong
Quang Special
Region, Cat Hai
FJ501523 FJ501345
Chirita longgangensis W.T.Wang
in Wang & Huang (1982: 171) A.Takhtajan & N.Aruzytov 1975
[Cult. RBGE 19941915] E Vietnam,
unknown
locality
AJ492290 FJ501347
Chirita minutimaculata D.Fang &
W.T.Wang in Wang (1981b: 55) J.M.Li 067134 PE China, Guangxi,
Longzhou
county
DQ872815 DQ872828
Chirita pinnata W.T.Wang
(1984a: 25) Expedition Beijing 896526 (US
294374) US China, Guangxi,
Rongshui county FJ501526 FJ501349
Chirita pinnatifida (Hand.-Mazz.)
B.L.Burtt (1960: 99) Q.J.Xie J-037 (US 422838) US China,
Guangdong,
Lianxian county
FJ501527 FJ501350
Chirita spinulosa D.Fang, &
W.T.Wang in Wang (1981b: 67) Y.Z.Wang 067133 PE China, Guangxi,
Fusui county DQ872813 DQ872830
Chiritopsis glandulosa D.Fang,
L.Zeng & D.H.Qin in Fang et al.
(1993: 470)
J.M.Li 054291 PE China, Guangxi,
Pingle county DQ872804 DQ872841
Chiritopsis repanda W.T.Wang
var. guilinensis W.T.Wang (1992:
299)
ex Smithsonian Institute 94-083
[Cult. RBGE 19951206] E China, Guangxi,
Guilin city AJ492292 FJ501351
Didymocarpus hancei Hemsley
(1890: 229) M.Möller MMO 08-1342 E China, Guangxi,
Hezhou city HQ632944 HQ633041
Didymocarpus niveolanosus
D.Fang & W.T.Wang in Wang &
Pan (1982: 133)
M.Möller MMO 06-861 E China, Guangxi,
Jingxi county JF697588 JF697576
Dolicholoma jasminiflorum
D.Fang & W.T.Wang in Wang
(1983b: 19)
M.Möller MMO 06-851 E China, Guangxi,
Napo county Wei et al.,
2010a Wei et al.,
2010a
Lagarosolen ainsliifolius
W.H.Chen & Y.M.Shui nomen
nudum
Y.M.Shui et al. 44071 KUN China, Yunnan,
Maguan county HQ632941 HQ633038
Lagarosolen coriaceifolius
Y.G.Wei (2006: 273) M.Möller MMO 06-913 E China, Guangxi,
Yangshuo
county
HQ632943 HQ633040
...... continued on the next page
Phytotaxa 23 © 2011 Magnolia Press 51
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
Plant names
For convenience and for avoiding confusion, the traditional names of the genera/species, as they appear in the
“Flora of China” (Wang et al. 1998), plus Wentsaiboea tiandengensis described recently in Liu et al. (2010),
are used in the text and in the phylogenetic trees. The current and new names of the Petrocodon alliance are
given in the formal treatment below.
TABLE 1 (continued)
Taxon Voucher number Deposited
in Origin trnL-F ITS or
ITS1 / ITS2
Lagarosolen hechiensis Y.G.Wei,
Yan Liu & F.Wen (2008: 299) M.Möller MMO 07-1077 E China, Guangxi,
Hechi city HQ632942 HQ633039
Lagarosolen hispidus W.T.Wang
(1984b: 12) Y.M.Shui et al. 82661 E China, Yunnan,
Maguan county HQ632939 HQ633036
Lagarosolen integrifolius D.Fang
& L.Zeng in Fang et al. (1993:
463)
M.Möller MMO 06-865 E China, Guangxi,
Longzhou
county
HQ632940 HQ633037
Lagarosolen lui Yan Liu &
W.B.Xu in Xu et al. (2010: 7) Y.G.Wei 8012 IBK China, Guangxi,
Jingxi county HQ632938 HQ633035
Lagarosolen sp.nov. Y.G.Wei 0903 IBK China, Guangxi,
Hechi city JF697589 JF697577
Loxostigma fimbrisepalum
K.Y.Pan in Wang & Pan (1982:
143)
Y.Z.Wang 991005 PE China, Yunnan,
Jinping county FJ501507 Wei et al.,
2010a
Loxostigma griffithii (Wight)
C.B.Clarke (1883: 60) Kew/Edinburgh Kanchenjunga
Expedition (1989) 940 [Cult.
RBGE 19892473A]
E Nepal,
Yamphudin FJ501508 FJ501338
Lysionotus pauciflorus
Maximowicz
(1874: 534)
M.Möller MMO 01-101 E, WU China, Yunnan,
Xichou county FJ501497 FJ501331
Lysionotus petelotii Pellegrin
(1930: 503) M.Möller MMO 01-100/4 E China, Yunnan,
road to Xichou FJ501496 HQ632974
Paralagarosolen fangianus
(Y.G.Wei) J.M.Li & Y.Z.Wang in
Wang et al. (2011: 60)
M.Möller MMO 07-1168 E China, Guangxi,
Napo county Wei et al.,
2010a Wei et al.,
2010a
Petrocodon dealbatus Hance
(1883: 167) Q.J.Xie J-042 (US 422841) US China,
Guangdong,
Lianxian county
FJ501537 FJ501358
Petrocodon dealbatus Hance var.
denticulatus (W.T.Wang)
W.T.Wang in Wang et al. (1990:
420)
Y.G.Wei 2010-03 IBK China, Guizhou,
Liping county JF697590 JF697578
Petrocodon ferrugineus Y.G.Wei
(2007: 135) M.Möller MMO 06-784 E China, Guangxi,
Xincheng county HQ632946 HQ633043
Primulina tabacum Hance (1883:
169) Q.J.Xie & C.X. Ye s.n. [Cult.
RBGE 19951540] E China,
Guangdong,
Lian River
AJ492300 FJ501352
Tengia scopulorum Chun (1946:
281, pl. 46) F.Wen 2010-02 IBK China, Guizhou,
Xiuwen county HQ632947 HQ633044
Wentsaiboea renifolia D.Fang &
D.H.Qin (2004: 534) M.Möller MMO 06-791 E China, Guangxi,
Duan county Wei et al.,
2010a Wei et al.,
2010a
Wentsaiboea tiandengensis Yan
Liu & B.Pan in Liu et al. (2010:
739, fig. 2-3E)
M.Möller MMO 07-1164 E China, Guangxi,
Tiandeng
county,
HQ632945 HQ633042
WEBER ET AL.52 Phytotaxa 23 © 2011 Magnolia Press
Samples used in the analysis
The ingroup comprises 17 samples, including seven species of Lagarosolen (L. coriaceifolius, L. hechiensis,
L. ainsliifolius, L. lui, L. integrifolius, L. hispidus, L. sp. nov.), the two species, plus a variety, of Petrocodon
(P. dealbatus, P. dealbatus var. denticulatus, P. ferrugineus), one species of Calcareoboea (C. coccinea), the
three monotypic genera Dolicholoma (D. jasminiflorum), Paralagarosolen (P. fangianus) and Tengia (T.
scopulorum), two samples of Didymocarpus (D. hancei, D. niveolanosus) and Wentsaiboea tiandengensis
(Liu et al. 2010). Other species of Didymocarpus form an independent clade and D. cortusifolius Léveillé
(1906: 427) is more closely related to Allocheilos Wang (1983a: 321) and Gyrocheilos Wang (1981a: 28)
(Möller et al. 2009, 2011a). The other two species of Wentsaiboea, including the type, W. renifolia, have been
included in Primulina (Wang et al. 2011).
DNA extraction, PCR, and sequencing
The molecular methods and protocols followed Möller et al. (2009, 2011a). For all samples sequences of both
the trnL-F intron-spacer (trnL-F) and the ITS regions were acquired. Newly acquired sequences were
deposited in GenBank.
Molecular-phylogenetic analysis
Maximum parsimony and Bayesian inference analyses were carried out as described in Möller et al. (2009,
2011a, b) and Weber et al. (2011), using PAUP* v4.0b10 (Swofford, 2002), and MrBayes v3.1.2
(Huelsenbeck & Ronquist 2001, 2007). Combined trnL-F and ITS sequences were analysed after their
combinability was checked using the incongruence length difference (ILD; P=0.22) test implemented as
partition homogeneity test (PHT) in PAUP*. Alignment gaps with consistent boundaries were coded as
additional characters according to the simple method of Simmons & Ochoterena (2000), 4 in trnL-F, 13 in
ITS. Parsimony branch support was obtained through bootstrap analyses as performed in Möller et al. (2009,
2011a) with 10000 replicates, TBR on, MulTrees off.
MrBayes settings for the best-fit models were selected separately for trnL-F, the ITS spacers and the 5.8S
gene by AIC in MrModeltest 2.3 (Nylander 2004), and were GTR+I, GTR+I+G and SYM+I, respectively,
gaps were treated as standard characters. For the 31 samples here 1.5 million generations were run. The burn-
in level was determined as 4% of the generations, after plotting likelihood values against generations
(Appendix 1). The posterior probabilities (PP) were obtained from MrBayes using the ‘sumt’ command. The
PP branch support values showed a high correlation between the two parallel Bayesian runs (Appendix 1).
Morphological analysis
Personal collections (by M. Möller), photographs and published descriptions of all species of the Petrocodon
clade were evaluated to assess the floral morphology of the species included in the analysis. Functional
conclusions were drawn from the floral characters established. Unfortunately, to date few field observations
on the pollination are available of the species concerned.
Results
Matrix characteristics
The Petrocodon matrix with 31 samples included 1566 characters (trnL-F: 847 characters, ITS: 719), of
which 241 (15.4%) were phylogenetically informative.
Phylogenetic analyses
The MP analysis of the combined data resulted in one most parsimonious tree (Fig. 1) of 816 steps
(CI=0.7145; RI=0.7658). The topology of the BI tree was identical (Fig. 2). Samples of the outgroup genera
Lysionotus, Loxostigma and Primulina each formed highly supported sister relationships (BS=100%;
Phytotaxa 23 © 2011 Magnolia Press 53
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
PP=1.00) and a monophyletic clade (BS=100%; PP=1.00) of Primulina (BS=100%; PP=1.00) sister to the
Petrocodon clade (BS=100%; PP=1.00) was retrieved. Our focus was on the latter clade, which was well
supported (BS=90%; PP=1.00). Didymocarpus niveolanosus and Lagarosolen hispidus (the type species of
that genus) formed a highly supported sister clade to the remaining samples, although this relationship
received low support (BS=57%; PP=0.84). The next clade to split off included four species (BS=72%;
PP=1.00), two Lagarosolen, Paralagarosolen fangianus and Wentsaiboea tiandengensis, but with low to
modest branch support. The last was sister to Lagarosolen lui (BS=77%; PP=0.82), and these were linked in
grades to Paralagarosolen (BS=59%; PP=0.91) and Lagarosolen integrifolius (BS=72%; PP=1.00).
FIGURE 1: Single most parsimonious tree based on combined trnL-F and ITS data plus gap characters. PHT: 0.22, 816 steps length,
CI= 0.7145; RI=0.7658 ; RC=0.5472. Numbers below branches are bootstrap values. * denote branches receiving <50% branch
support. Number of fertile stamens (stam.: a, anterior pair), corolla shape, colour, capsule shape and dehiscence (4v, dehiscing into 4
valves), and stigma characters indicated in box.
The remaining 11 samples formed a strongly supported clade (BS=94%; PP=1.00) but with few well
supported internal branches. Lagarosolen ainsliifolius nomen nudum and Dolicholoma jasminiflorum formed
a clade with medium MP branch support (BS =77%), but high BI support (PP=1.00). The relationship of the
WEBER ET AL.54 Phytotaxa 23 © 2011 Magnolia Press
two Lagarosolen samples, L. hechiensis and L. sp. nov., received some support (BS=63%; PP=0.82). Within
this clade, the three Petrocodon samples (P. ferrugineus, P. dealbatus, P. dealbatus var. denticulatus), Tengia
scopulorum and Lagarosolen coriaceifolius formed a very strongly supported clade (BS=97%; PP=1.00).
Among these, the two Petrocodon dealbatus varieties were closely related (BS=89%; PP=1.00).
FIGURE 2: Bayesian inference tree with average branch lengths, based on combined trnL-F, ITS and alignment gap characters.
Numbers below branches are posterior probabilities. Bars indicate radiation events.
Discussion
Phylogenetic considerations
For morphologically complex groups of plants, the reconstruction of phylogenetic relationships based on
independent data, such as neutrally evolving molecular DNA sequences, is an important tool to understand the
morphological diversification within these groups.
Following Möller et al. (2011a), we reconstructed the phylogenetic relationships for the Petrocodon
clade, a highly supported clade of advanced didymocarpoid Gesneriaceae, dominated by species of the genus
Lagarosolen. This clade contains species of eight genera, with Didymocarpus, Lagarosolen and Petrocodon
represented by more than one species each. None of these genera formed monophyletic subclades, neither in
Phytotaxa 23 © 2011 Magnolia Press 55
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
the MP nor the BI analyses of the combined data set (Figs. 1, 2), nor in individual trnL-F and ITS analyses
(data not shown). This demonstrates that the current classification does not reflect relationships by descent
correctly. We consider our analysis as highly representative since we included all but three species
[Calcareoboea bonii = Didymocarpus bonii; Petrocodon angustifolius nomen nudum, described and
illustrated in Wei et al. (2010b), but not yet validly published; and P. multiflorus, recently described by Jiang
et al. 2010] of the genera retrieved exclusively in the Petrocodon clade. It is unlikely that their addition will
significantly change our present results.
The phylogenetic trees of the didymocarpoid Gesneriaceae, particularly in the BI analysis, were
characterised by short internal and long terminal branches (Möller et al. 2009, 2011a). This was found
particularly in the Petrocodon clade but also, to a lesser degree, in the Primulina clade retrieved in the present
study (Fig. 2). This suggests rapid evolutionary radiations. The Petrocodon clade has apparently experienced
several such radiation events, once at the beginning of its diversification, once later in the middle of its
evolution, and once more recently for a group of five species hitherto placed in three different genera (Fig. 2).
This burst of speciation, leading to a high diversity in floral characteristics, may well be linked to the repeated
diversification of pollination syndromes, since similar ones are scattered throughout the phylogenetic tree
(Figs. 2, 3).
Morphological-taxonomical considerations
The alliance under consideration can be distinctively characterised as to the vegetative habit and the
inflorescences: all taxa are rhizomatous rosette plants (with apparently alternate leaf arrangement, Fig. 4) and
scapose, axillary inflorescences. Leaves are usually elliptic or ovate (Fig. 4). The flowers in the Petrocodon
clade are arranged in few- to several-flowered aggregates (pair-flowered cymes), rarely are the cymes reduced
to single flowers. There are also strong agreements in the flower characters, especially in those that have been
used to delineate genera, such as the number of fertile stamens, and stigma shape: with the exception of
Tengia (with five stamens in the pentamerous, actinomorphic flowers), the flowers of all taxa are diandrous
and zygomorphic. The stigma is capitate or slightly bilobed, with an upper and lower lobe, corresponding to
“two stigmas” in Wang’s terminology (e.g., Wang et al. 1998). The greatest variation is in the corolla form and
coloration (Fig. 3), and this was the basis on which the originally circumscribed six genera were
differentiated.
In the following discussion, the genera of the Petrocodon clade are addressed in some closer detail. We
argue that the floral dissimilarities can be interpreted as reflecting different pollination syndromes.
Petrocodon and Tengia (Fig. 3L & M). The close (or at least possible) relationship of Petrocodon and
Tengia has been addressed in the literature long before the advent of molecular systematics: while Wang et al.
(1990, 1998) considered Tengia to be related to other genera with actinomorphic flowers and placed Tengia in
tribe Ramondieae (sensu Wang et al. 1990), Burtt (1970) much earlier had predicted a very close relationship
of Tengia with Petrocodon (tribe Didymocarpeae). Burtt argued that both have a similar, white, urceolate
corolla, and differ only in the number of stamens: Petrocodon has only two stamens, while Tengia has five.
Moreover, Burtt concluded that the corolla actinomorphy and pentandry of Tengia is an evolutionarily
secondary condition, derived from corolla zygomorphy and tetrandry or diandry (here we confirm its
descendance from diandry). Indeed, it has been recently confirmed by molecular studies that genera with
actinomorphic flowers do not represent a monophyletic group and that floral actinomorphy has secondarily
and independently evolved in several alliances of the didymocarpoid Gesneriaceae (Möller et al. 1999, 2009,
Wang et al. 2010).
Calcareoboea and Didymocarpus (Fig. 3A, G & J). Burtt (2001) took a taxonomic decision which is
difficult for the outsider to understand: he transferred Didymocarpus bonii to the hitherto monotypic
Calcareoboea and he also announced inclusion of Didymocarpus hancei in that genus. Calcareoboea and the
two species of Didymocarpus have extremely different flowers: Calcareoboea has long-tubular, bright red
flowers with a four-toothed upper lip and a single-toothed lower lip, while the other two Didymocarpus
species have shortly campanulate, light-coloured flowers with a two-lobed upper lip and a three-lobed lower
WEBER ET AL.56 Phytotaxa 23 © 2011 Magnolia Press
lip. Burtt (2001: 86) recognised that “the floral differences were associated with the pollination mechanisms
of the plants, and such features are known to be unreliable as sole generic criteria”.
Our data show that Didymocarpus hancei indeed falls into the Petrocodon clade (Figs. 1, 2). Within that
clade, it is not particularly close to Calcareoboea, but the general affinity is in agreement with Burtt’s
prediction. Currently, there are no molecular data pertaining to the placement of Didymocarpus bonii, but we
are confident that Burtt (2001) was correct and, moreover, that (at least) one more species of Didymocarpus
(D. mollifolius) belongs to this alliance. Calcareoboea coccinea was already included in Petrocodon by Wang
et al. (2011) and needs no further discussion.
Lagarosolen and Paralagarosolen (Fig. 3B, C, E, H & K). The name of the latter already suggests its
close affinity with Lagarosolen. The two genera share a rather narrow-cylindrical, not pouched corolla tube
and a bilobed stigma, but Paralagarosolen was said to differ from Lagarosolen in “having leaves sometimes
peltate at base, cyme with only one flower, corolla lobes rounded-obtuse at apex, and capsule ovoid-ellipsoid”
(Wei 2004: 528). These characters, however, hardly warrant generic separation. Peltate leaves occur in species
of several genera [e.g. Cyrtandra peltata Jack (1823: 30), Briggsia longipes Craib (1920: 262), Drymonia
peltata (Oliv.) Moore (1955: 112), Metapetrocosmea peltata (Merr. & Chun) Wang (1981b: 39), Petrocosmea
peltata Merrill & Chun (1935: 320), Paraboea peltifolia D.Fang & L.Zeng in Fang et al. (1995: 606),
Sinningia tuberosa (Mart.) Moore (1973: 40)], the reduction of the cymes to single flowers is a common
phenomenon, rounded-obtuse (vs. acute) corolla lobes occur also in Lagarosolen jingxiensis and L. lui (Wei et
al. 2010b: 263, 264). Although a slender (“linear”) fruit seems to be characteristic of Lagarosolen (but the
fruit is unknown in some species), L. lui has an “elliptic” fruit (Wei et al. 2010b: 265). Consequently, the
generic separation appears rather weak and Lagarosolen itself is heterogeneous in floral characters. The
corolla morphology of the type species (L. hispidus: narrow tube tapering toward the base, corolla lobes
narrowly triangular, acute at tip and projecting forward) is only found in a few species. L. coriaceifolius has a
distinctly broader tube and broadly triangular lobes, L. hechiensis has an infundibuliform flower with patent,
acute lobes, and L. jingxiensis and L. lui have a patent limb with rounded corolla lobes. The genus, based
essentially on corolla characters, is thus not very well characterised. This is likely the reason why the species
of Lagarosolen appear scattered over the whole clade - they do not form a coherent group, neither in their
molecular characteristics nor in floral morphology.
Dolicholoma (Fig. 3F). The narrow tube and the subactinomorphic limb with long, acute lobes are shared
between Dolicholoma and Lagarosolen. It is difficult to understand why Wang (1984b), when establishing
Lagarosolen, did not address the floral similarity of the two genera. When establishing Dolicholoma D.Fang
& W.T.Wang in Wang (1983b), the authors placed that genus in the proximity of Didymocarpus, while they
referred Lagarosolen in the proximity of Chirita Buch.-Ham. ex Don (1825: 89). The reason was probably the
difference in the stigma (“disciform” in Dolicholoma, and “shortly bilobed” in Lagarosolen).
Pollination syndromes
It is conceivable that the considerable diversity in floral forms and coloration have a functional background.
In the absence of flower visitor data, likely pollination syndromes have to be inferred from floral morphology.
In fact, the eye-catching flowers of some taxa, in particular the red, tubular flowers of Calcareoboea, the
white, bell-shaped flowers of Petrocodon and Tengia, the narrow-tubed, light-coloured flowers of
Paralagarosolen and some Lagarosolen species, and the oblique-campanulate flowers of the species of
Didymocarpus included here, can be related to pollination syndromes. The flowers of Calcareoboea can be
classified as bird pollinated flowers. The corolla colour (bright red), corolla form (tubular, widening toward
the limb), position of stamens (beneath the corolla roof), limb structure (upper lip of four small tooth-like and
downcurved corolla lobes forming a helmet, lower lip of a single recurved lobe), the presence of a well-
developed, cup-shaped nectary, the horizontal or downward-inclined position of the flowers, their number and
arrangement into a wreath radiating in all directions (thus eye-catching and visible from far away), and the
long, stout peduncle suggests that the bird perches on the peduncle and enters the flower with the beak from
below, the pollen being deposited on the beak or forehead (nototribic pollen deposition).
Phytotaxa 23 © 2011 Magnolia Press 57
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
FIGURE 3: Examples of flower morphology of various taxa belonging to the Petrocodon clade arranged by phylogenetic
relationships as suggested by the molecular data: A, Didymocarpus niveolanosus; B, Lagarosolen integrifolius; C, Paralagarosolen
fangianus; D, Wentsaiboea tiandengensis; E, Lagarosolen ainsliifolius; F, Dolicholoma jasminiflorum; G, Calcareoboea coccinea; H,
Lagarosolen hechiensis; J, Didymocarpus hancei; K, Lagarosolen coriaceifolius; L, Tengia scopulorum; M, Petrocodon dealbatus.
WEBER ET AL.58 Phytotaxa 23 © 2011 Magnolia Press
FIGURE 4: Examples of vegetative habit of various taxa belonging to the Petrocodon clade: A, Petrocodon ferrugineus; B,
Didymocarpus hancei; C, Didymocarpus niveolanosus.
The corolla form (bell-shape or urceolate), the apically confluent locules of the anthers, the small (non-
functional?) ring-like nectary, and the nodding position of the flowers of Petrocodon and Tengia suggest buzz-
pollination by bees (see also Wang et al. 2010). The long, narrow-tubed, hypocrateriform flowers of
Dolicholoma, Paralagarosolen and some species of Lagarosolen suggest pollination by butterflies. Other
species of Lagarosolen are possibly bee-pollinated and the same certainly applies for the obliquely
campanulate flower of the relevant Didymocarpus species.
The floral diversity thus approaches to some extent that of some neotropical genera such as Achimenes
Persoon (1807: 164), Gasteranthus Bentham (1846: 233) or Sinningia Nees von Esenbeck (1825: 297) (e.g.,
Wiehler 1983, Perret et al. 2001, 2003, Skog & Kvist 2000, Roalson et al. 2002, 2003).
Taxonomic consequences
The distribution of genetic diversity (branch lengths) of the highly supported Petrocodon clade (Möller et al.
2011a, and present results), the erratic distribution of the Lagarosolen species, and the divergent corolla
morphology on which the genera have been based (likely reflecting different pollination syndromes) lead us to
the conclusion that this clade is an alliance of species which has experienced radiations during its evolution
involving often parallel adaptations to different pollinators. The largest genus in the alliance, Lagarosolen,
with seven species, is apparently polyphyletic and heterogeneous, as indicated by the molecular data and
supported by the heterogeneity of the corolla characters. In view of the fact that the genera were based solely
on corolla characters, that the corolla characters can be associated with pollination syndromes, and that
Lagarosolen is apparently polyphyletic, it seems best to dispense with the traditional genera and to include the
genera and species discussed into Petrocodon (the oldest generic name). Wiehler’s credo “pollination
syndromes do not constitute genera” (Wiehler 1983), has seemingly not found much echo in the taxonomy of
Old World Gesneriaceae so far, but the present work represents an important step in this direction. Principally,
our taxonomic decision is in agreement with the conclusions of Wang et al. (2011), but the present
circumscription of Petrocodon is much wider, including Lagarosolen, Dolicholoma, particular species of
Didymocarpus, and a species described recently under Wentsaiboea.
With regard to Didymocarpus, molecular data were available for D. hancei and D. niveolanosus. These
species are apparently related to D. mollifolius, which we also transfer to Petrocodon. As Burtt (2001) has
transferred D. bonii to Calcareoboea, we retain it in Petrocodon as well. In all of these cases, molecular data
are needed to confirm their positions.
There are also a number of species, which have been described (but not formally established) and are
illustrated in Y.G. Wei et al.’s splendid book “Gesneriaceae of South China” (Wei et al. 2010b). One species
Phytotaxa 23 © 2011 Magnolia Press 59
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
has been described under Petrocodon (P. angustifolius nomen nudum) and two under Lagarosolen (L.
ainsliifolius nomen nudum, L. sp. nov.) (see also below). Available molecular data show, that they all fall into
the Petrocodon clade and should be validly described under this genus. In total, including the unpublished
species, Petrocodon encompasses more than 20 species, which is four times as many as in the concept of
Wang et al. (2011).
Formal treatment
Petrocodon Hance (1883: 167).
Typ e: Petrocodon dealbatus Hance.
Heterotypic synonyms:
Didymocarpus Wallich (1819: 378), pro parte excl. type. Type: D. primulifolius D.Don.
Tengia Chun (1946: 279). Type: Tengia scopulorum Chun.
Calcareoboea C.Y.Wu ex Li (1982: 241). Type: Calcareoboea coccinea C.Y.Wu ex H.W.Li.
Dolicholoma D.Fang & W.T.Wang in Wang (1983b: 18). Type: Dolicholoma jasminiflorum D.Fang &
W.T. Wan g.
Lagarosolen Wang (1984b: 11). Type: Lagarosolen hispidus W.T.Wang.
Paralagarosolen Wei (2004: 528). Type: Paralagarosolen fangianus Y.G.Wei.
Wentsaiboea Fang & Qin (2004: 533), pro parte excl. type. Type: W. renifolia D. Fang & D.H.Qin = Primulina
renifolia (D.Fang & D.H.Qin) Y.Z.Wang in Wang et al. (2011: 62).
Petrocodon bonii (Pellegr.) A.Weber & Mich.Möller, comb. nov.
Basionym:—Didymocarpus bonii Pellegrin (1926: 416).
Homotypic synonym:—Calcareoboea bonii (Pellegr.) Burtt (2001: 86).
Notes:—Molecular data are lacking for this species, the transfer is fide Burtt (2001), who included
Didymocarpus bonii in Calcareoboea as a second species and predicted (correctly) that also D. hancei is
closely allied to Calcareoboea. Nevertheless, confirmation is needed.
Petrocodon coccineus (C.Y.Wu ex H.W.Li) Y.Z.Wang in Wang et al. (2011: 60).
Basionym:—Calcareoboea coccinea C.Y.Wu ex Li (1982: 243, fig. 1).
Petrocodon coriaceifolius (Y.G.Wei) Y.G.Wei & Mich.Möller, comb. nov.
Basionym:—Lagarosolen coriaceifolius Wei (2006: 273, fig. 1; “L. coriaceifolium”).
Petrocodon dealbatus Hance (1883: 167).
Heterotypic synonym:—Petrocodon longistylus Kraenzlin (1928: 216).
Petrocodon dealbatus var. denticulatus (W.T.Wang) W.T.Wang in Wang et al. (1990: 420).
Basionym:—Petrocodon denticulatus Wang (1975: 101).
Petrocodon fangianus (Y.G.Wei) J.M.Li & Y.Z.Wang in Wang et al. (2011: 60).
Basionym:—Paralagarosolen fangianus Wei (2004: 529, fig. 1).
Petrocodon ferrugineus Y.G.Wei (2007: 135, fig. 1).
Petrocodon hancei (Hemsl.) A.Weber & Mich.Möller, comb. nov.
Basionym:—Didymocarpus hancei Hemsley (1890: 229).
WEBER ET AL.60 Phytotaxa 23 © 2011 Magnolia Press
Petrocodon hechiensis (Y.G.Wei, Yan Liu & F.Wen) Y.G.Wei & Mich.Möller, comb. nov.
Basionym:—Lagarosolen hechiensis Wei, Liu & Wen (2008: 299, fig. 1).
Petrocodon hispidus (W.T.Wang) A.Weber & Mich.Möller, comb. nov.
Basionym:—Lagarosolen hispidus Wang (1984b: 12).
Petrocodon integrifolius (D.Fang & L.Zeng) A.Weber & Mich.Möller, comb. nov.
Basionym:—Lagarosolen integrifolius D.Fang & L.Zeng in Fang et al. (1993: 463).
Petrocodon jasminiflorus (D.Fang & W.T.Wang) A.Weber & Mich.Möller, comb. nov.
Basionym:—Dolicholoma jasminiflorum D.Fang & W.T.Wang in Wang (1983b: 19).
Petrocodon jingxiensis (Yan Liu, H.S.Gao & W.B.Xu) A.Weber & Mich.Möller, comb. nov.
Basionym:—Lagarosolen jingxiensis Liu, Gao & Xu (2008: 274, fig. 1).
Petrocodon lui (Yan Liu & W.B.Xu) A.Weber & Mich.Möller, comb. nov.
Basionym:—Lagarosolen lui Yan Liu & W.B.Xu in Xu et al. (2010: 7, fig. 1).
Petrocodon mollifolius (W.T.Wang) A.Weber & Mich.Möller, comb. nov.
Basionym:—Didymocarpus mollifolius Wang (1984b: 21).
Notes:—No molecular data available, but the species is similar to P. hancei and P. niveolanosus. The three
species form a group of rosette plants (very unlike true Didymocarpus, for the morphology of which see
Weber & Burtt 1998) with oblong or oblanceolate leaves with pinnate venation.
Petrocodon multiflorus F.Wen & Y.S.Jiang in Jiang et al. (2011: 57).
Notes:—No molecular data available.
Petrocodons niveolanosus (D.Fang & W.T.Wang) A.Weber & Mich.Möller, comb. nov.
Basionym:—Didymocarpus niveolanosus D.Fang & W.T.Wang in Wang & Pan (1982: 133).
Petrocodon scopulorum (Chun) Y.Z.Wang in Wang et al. (2011: 60, as: ‘P. scopulorus’).
Basionym:—Tengia scopulorum Chun (1946: 281, pl. 46).
Heterotypic synonym:—Tengia scopulorum Chun var. potiflora (S.Z.He) W.T.Wang, A.L.Weitzman &
L.E.Skog in Weitzmann et al. (1998: 434).
Basionym:—Tengia potiflora S.Z.He in He & Cong (1992: 269).
Notes:—Following Wei et al. (2010b) and Wang et al. (2011), Tengia scopulorum var. potifolia is included
here in typical P. scopulorum. Wang's spelling "scopulorus" is corrected here into "scopulorum", as this is the
genetivus pluralis of scopulus, Lat. (meaning cliff or rock).
Petrocodon tiandengensis (Yan Liu & B.Pan) A.Weber & Mich.Möller, comb. nov.
Basionym:—Wentsaiboea tiandengensis Yan Liu & B.Pan in Liu et al. (2010: 739, fig. 2–3E).
The following species are also relevant:
Lagarosolen ainsliifolius W.H.Chen & Y.M.Shui, nom. nud. (Shui & Chen 2006: 169, Wei et al. 2010b: 266,
in both as: ‘L. ainsliifolia’).
Notes:—Described and illustrated, but not validly published in Shui & Chen (2006) and Wei et al. (2010b).
Included in the present molecular analysis.
Phytotaxa 23 © 2011 Magnolia Press 61
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
Lagarosolen sp. nov., voucher: Y.G. Wei 0903.
Notes:—Included in the present molecular analysis.
Petrocodon angustifolius Y.G.Wei, F.Wen & H.Z.Lü, nom. nud. (Wei et al. 2010b: 538, as: ‘L. angustifolia’).
Notes:—Described and illustrated, but not validly published in Wei et al. (2010b). No molecular data
available.
Acknowledgements
The work was carried out in cooperation between the University of Vienna (supported by the Austrian Science
Fonds, FWF-Proj. No. P-13107-Bio), the Guangxi Institute of Botany and the Royal Botanic Garden
Edinburgh (RBGE). We are grateful to Robert Mill for a critical reading of the manuscript. RBGE is
supported by the Scottish Government Rural and Environment Research and Analysis Directorate (RERAD).
Fieldwork of MM was supported by the RBGE Expedition Fund and of FW by the Guangxi Natural Science
Foundation (2011GXNSFB018050). YGW benefitted from support through the Science & Technology
Innovation Program of the Guangxi Academy of Sciences Fund.
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WEBER ET AL.64 Phytotaxa 23 © 2011 Magnolia Press
Appendix 1: Diagnostics of the Bayesian inference analysis of the Petrocodon dataset of combined
trnL-F and ITS sequence data plus alignment gap matrix.
Number of taxa = 31
Number of characters = 1566
Number of generations = 1500000
Average standard deviation of split frequencies: 0.002526
Analysis completed in 13383 seconds
Analysis used 13382.17 seconds of CPU time
Likelihood of best state for "cold" chain of run 1 was -6919.19
Likelihood of best state for "cold" chain of run 2 was -6924.13
Acceptance rates for the moves in the "cold" chain of run 1:
With prob. Chain accepted changes to
59.19 % param. 1 (revmat) with Dirichlet proposal
27.56 % param. 2 (revmat) with Dirichlet proposal
67.94 % param. 3 (revmat) with Dirichlet proposal
19.72 % param. 4 (state frequencies) with Dirichlet proposal
19.96 % param. 6 (state frequencies) with Dirichlet proposal
91.82 % param. 9 (gamma shape) with multiplier
47.26 % param. 10 (prop. invar. sites) with sliding window
13.38 % param. 11 (topology and branch lengths) with extending TBR
20.35 % param. 11 (topology and branch lengths) with LOCAL
Acceptance rates for the moves in the "cold" chain of run 2:
With prob. Chain accepted changes to
59.53 % param. 1 (revmat) with Dirichlet proposal
27.31 % param. 2 (revmat) with Dirichlet proposal
67.48 % param. 3 (revmat) with Dirichlet proposal
19.73 % param. 4 (state frequencies) with Dirichlet proposal
19.71 % param. 6 (state frequencies) with Dirichlet proposal
91.67 % param. 9 (gamma shape) with multiplier
47.43 % param. 10 (prop. invar. sites) with sliding window
13.37 % param. 11 (topology and branch lengths) with extending TBR
20.57 % param. 11 (topology and branch lengths) with LOCAL
Chain swap information for run 1:
1 2 3 4
----------------------------------
1 | 0.34 0.08 0.02
2 | 249733 0.43 0.13
3 | 249575 249342 0.48
4 | 250971 249797 250582
Chain swap information for run 2:
1 2 3 4
----------------------------------
1 | 0.34 0.08 0.02
2 | 250320 0.42 0.13
3 | 249876 250915 0.47
4 | 250135 249156 249598
Upper diagonal: Proportion of successful state exchanges between chains
Lower diagonal: Number of attempted state exchanges between chains
Phytotaxa 23 © 2011 Magnolia Press 65
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
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WEBER ET AL.66 Phytotaxa 23 © 2011 Magnolia Press
Petrocodon combined data. Posterior probabilities run 1 versus run 2.
Petrocodon combined data: Symmetric tree differences within and between run 1 vs run 2.
Phytotaxa 23 © 2011 Magnolia Press 67
A NEW DEFINITION OF THE GENUS PETROCODON (GESNERIACEAE)
Run 1
Run 2
... Möller, and Thailand with only two species, P. flavus D.J. Middleton & Sangvir. and P. bonii (Pellegrin 1926, Li 1982, Burtt 2001, Weber et al. 2011, Middleton et al. 2015. ...
... Another population of this new taxon in Hoa Binh province consisted of about 500 mature individuals, all growing on the cliffs at the entrance to a cave near farmland, where they are easily disturbed by human activities. (Li 1982, Burtt 2001 (Wang et al. 2011, Weber et al. 2011. The vegetative characters of these two species are so much alike that it is hard to distinguish between them if not in flower. ...
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Petrocodon vietnamensis, a new species from karst cave in north Vietnam is described and illustrated. It is morphologically close to P. bonii, but can be distinguished from the latter by having a green, 3–6 cm long peduncle; green, ca 5 mm long calyx lobes; narrow infundibuliform, a 1.1–1.2 cm long corolla tube; ovate abaxial lip lobes; pink to white, 9.5–10.5 mm long filaments; lateral staminodes adnate to ca 12 mm above the corolla base; densely white glandular-puberulent pistil; a pink to white, 5.5–7.5 mm long style; a white stigma, and a 2–3 cm long capsule. Information on ecology, phenology, preliminary conservation assessment of the new species and a key for the taxonomic identification of Petrocodon species in Vietnam are also provided.
... It was confirmed and published using classical taxonomy, palynology, and phylogenetic analysis (Wei et al. 2010). Since then, some redefined genera, such as Hemiboea Clarke (Weber et al. 2011a), Loxostigma Clarke (Möller et al. 2014), Oreocharis , Paraboea (Clarke) Ridley (Puglisi et al. 2011), Petrocodon Hance (Weber et al. 2011b), Primulina Hance (Weber et al. 2011c), etc., and newly divided or restored genera, for example, Glabrella Mich. Möller & W.H.Chen (Möller et al. 2014) and Bournea Oliv. ...
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Actinostephanus, a new genus from southern China, is described and colorfully illustrated with a single species, A. enpingensis. This new genus is morphologically most similar to Boeica and Leptoboea, nevertheless, it can be easily distinguished from the latter two by the following characteristics, such as leaves in whorls of three, all closely clustered at the top; corolla bowl-shaped, 5-lobed, actinomorphic; capsule hard, oblong-ovoid, short, 3-4 mm long, densely appressed villous, wrapped by persistent densely pubescent calyx lobes, style persistent. The new genus and related genera were sequenced using the next-generation sequencing technique. The whole plastid genome of the new genus is 154, 315-154, 344 bp in length. We reconstructed phylogenetic trees using the dataset of 80 encoded protein genes of the whole plastid genome from 47 accessions based on ML and BI analyses. The result revealed that the new genus was recovering in a polytomy including Boeica, A peer-reviewed open-access journal Fang Wen et al. / PhytoKeys 193: 89-106 (2022) 90 Rhynchotechum, and Leptoboea with strong support, congruent to the morphological evidence. A global conservation assessment was also performed and classifies A. enpingensis as Least Concern (LC). In addition, after a review of recently described species of Gesneriaceae, we propose that plant enthusiasts, especially Gesneriad fans, have been playing an increasingly important role in the process of new taxa-discoveries.
... It was confirmed and published using classical taxonomy, palynology, and phylogenetic analysis (Wei et al. 2010). Since then, some redefined genera, such as Hemiboea Clarke (Weber et al. 2011a), Loxostigma Clarke (Möller et al. 2014), Oreocharis , Paraboea (Clarke) Ridley (Puglisi et al. 2011), Petrocodon Hance (Weber et al. 2011b), Primulina Hance (Weber et al. 2011c), etc., and newly divided or restored genera, for example, Glabrella Mich. Möller & W.H.Chen (Möller et al. 2014) and Bournea Oliv. ...
Preprint
Full-text available
Actinostephanus , a new genus from southern China, is described and colorfully illustrated with a single species, A. enpingensis . This new genus is morphologically most similar to Boeica and Leptoboea , nevertheless, it can be easily distinguished from the latter two by the following characteristics, such as leaves in whorls of three, all closely clustered at the top; corolla bowl-shaped, 5-lobed, actinomorphic; capsule hard, oblong-ovoid, short, 3–4 mm long, densely appressed villous, wrapped by persistent densely pubescent calyx lobes, style persistent. The new genus and related genera were sequenced using the next-generation sequencing technique. The whole plastid genome of the new genus is 154, 315 - 154, 344 bp in length. We reconstructed phylogenetic trees using the dataset of 80 encoded protein genes of the whole plastid genome from 47 accessions based on ML and BI analyses. The result revealed that the new genus was recovering in a polytomy including Boeica , Rhynchotechum , and Leptoboea with strong support, congruent to the morphological evidence. A global conservation assessment was also performed and classifies A. enpingensis as Least Concern (LC). In addition, after a review of recently described species of Gesneriaceae, we propose that plant enthusiasts, especially Gesneriad fans, have been playing an increasingly important role in the process of new taxa-discoveries.
... ex de Candolle (1845: 265)] reaching northern Sumatra . Currently, Didymocarpus contains ca. 100 species (Möller 2019, Prasanna et al. 2020, of which 34 (including four varieties) occur in China (Li & Wang 2004, Weber et al. 2011, Wen et al. 2013, Li & Li 2014, Li & Wang 2015, Cai et al. 2016, Li et al. 2016, Yang et al. 2019, Xie et al. 2020, Zhang et al. 2020 (Wang et al. 1990, Li & Wang 2004). The former is characterized by caulescent perennial herbs with opposite leaves, connate or free large bracts, and slender or tubular corolla tube, while the latter can be characterized by acaulescent perennial herbs with rosulate leaves, small free bracts, and funnelform corolla tube. ...
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Didymocarpus cordifolius, a new species of Gesneriaceae from southern Yunnan Province, China is described and illustrated. The new species is morphologically similar to D. silvarum and D. margaritae, but can be readily distinguished by its short petioles with both glandular and eglandular hairs, pale purple corolla, hairy anthers, and ovary and style of subequal length.
... In a broad concept, it had been considered including about 180 species widely distributed in tropical Asia, with a few species in Madagascar and Australia (Wang 1990). Recent morphological and molecular studies have led to a narrower circumscription of the genus (Weber & Burtt 1998;Weber et al. 2000;Weber et al. 2011;Möller et al. 2011;Möller & Clark 2013;Li et al. 2016). Nearly 100 species mostly from southern India, Sri Lanka, southern Thailand and Malesia were transferred to three reinstated genera, viz. ...
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Didymocarpus longicalyx, a new species of Gesneriaceae from southwestern Yunnan Province, China is described and illustrated based on detailed morphological comparisons with all known species of the genus Didymocarpus from both China and neighbouring countries. Morphologically, it is most similar to D. medogensis and D. glandulosus, but can be distinguished by its puberulent peduncles, calyx with ca. 8 mm long segments and claret corollas with three yellow spots and a few yellowish striations on upper lip.
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