Molecular and morphological evidence for a new species of Isodon (Lamiaceae) from southern China
Ya-Ping Chena, Cun-Zhong Huangb, Yue Zhaoa,c, Chun-Lei Xianga     
a. CAS Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, Yunnan, China;
b. Natural Resources Bureau of Guidong County, Chenzhou 423000, Hunan, China;
c. University of Chinese Academy of Sciences, Beijing 100049, China
Abstract: Isodon brevipedunculatus, a new species from southern China, is described and illustrated. The phylogenetic position of the new species within the genus was analyzed based on two nuclear ribosomal DNA regions and an ingroup sampling of about 80% of Asian species of Isodon. The results show that I. brevipedunculatus is recovered in a clade that consists of species mainly with glandular mericarps and that are distributed in the Sino-Japanese region. Combining molecular and geographical evidence, our study reveals that I. brevipedunculatus is most closely related to Isodon amethystoides and Isodon bifidocalyx, but differs from the former in lamina shape, number of flowers per cyme, and peduncle length, and from the latter in lamina indumentum, calyx morphology, and corolla length.
Keywords: Himalaya-Hengduan Mountains region    Isodoninae    Mericarp    Sino-Japanese region    
1. Introduction

Isodon (Schrad. ex Benth.) Spach is one of the largest genera in Lamiaceae with approximately 100 species distributed mainly in tropical and subtropical Asia (Harley et al., 2004; Li, 1988; Li and Hedge, 1994; Mabberley, 2008; Wu and Li, 1977). The Himalaya-Hengduan Mountains (HHM) global biodiversity hotspot, which accommodates ca. 70% of the species of Isodon, is considered the distribution and biodiversity center of the genus (Yu et al., 2014; Zhong et al., 2010). Isodon is recognized as the only genus in subtribe Isodoninae (Zhong et al., 2010), and it differs from other genera of Ocimeae by its pedunculate and bracteolate cymes, slightly or strongly 2-lipped (3/2) calyces, strongly 2-lipped (4/1) corollas, and free filaments inserted at the base of the corolla tube (Harley et al., 2004; Li, 1988; Paton and Ryding, 1998). Some species of Isodon have long been used as traditional folk medicine in China and Japan, and contemporary phytochemical studies of Isodon species have so far isolated and identified more than 1200 diterpenoids, some of which have important pharmaceutical functions (Liu et al., 2017; Sun et al., 2006).

Several new species of Isodon have been reported from China during the last decade (Chen et al., 2014, 2016b, 2017, 2019; Xiang and Liu, 2012). Recently, we collected a distinct species of Isodon from Hunan and Guangdong Provinces in southern China. Critical studies based on specimen and literature examination, as well as molecular phylogenetic analyses revealed it to be an undescribed species. Herein, we describe and illustrate the new species.

2. Material and methods 2.1. Morphological and taxonomic studies

Comparison of morphological features between the new species and other species of Isodon were carried out based on our previous field observations, specimen examination, and unpublished mericarp data (Chen, 2017). Specimens of Isodon from 29 herbaria (A, AU, BM, CDBI, CSFI, E, G, GXMI, HHBG, HIB, IBK, IBSC, K, KUN, KYO, L, LBG, LE, MW, NAS, P, PE, S, SYS, SZ, TAI, TI, W, and WUK; abbreviations follow Thiers, 2020) and our field collections were examined. Meanwhile, protologues of all published names and all other taxonomic literature for Isodon were reviewed. The terminology used by Li (1988) and Li and Hedge (1994) was adopted for the morphological description of the new species.

2.2. Taxon sampling and DNA amplification

The systematic placement of the new species was explored based on an ingroup sampling comprising 90 accessions of 84 species of Isodon from Asia, including two individuals of the new species from the type locality in Guangdong Province and from Hunan Province, respectively (Appendix A). Six genera representing all subtribes of Ocimeae except Isodoninae (Harley et al., 2004; Zhong et al., 2010) were selected as outgroups (Appendix A). Previous studies have shown that Isodon chloroplast DNA sequences have significantly lower numbers of variable sites than nuclear DNA sequences, and consequently generate poorly resolved phylogenies (Chen et al., 2019; Yu et al., 2014; Zhong et al., 2010). Thus, for phylogenetic analyses, we used two nuclear ribosomal DNA markers: the nuclear ribosomal internal and external transcribed spacers (ITS and ETS). A total of 172 sequences were downloaded from GenBank to complement our dataset, of which 168 sequences were generated from our previous study (Chen et al., 2019). Voucher information and GenBank accession numbers for all sequences are listed in Appendix A.

The modified CTAB method (Doyle and Doyle, 1987) was used to extract genomic DNA from the silica-gel-dried leaf material. For polymerase chain reaction (PCR) amplification, ITS was amplified using the primer pairs 17SE/26SE (Sun et al., 1994), ETS using ETS-B (Beardsley and Olmstead, 2002) and 18S-IGS (Baldwin and Markos, 1998). The PCR and sequencing protocols for the two markers followed those of Chen et al. (2016a).

2.3. Sequence alignment and phylogenetic analyses

Sequences were assembled and edited using Sequencher 4.1.4 (Gene Codes, Ann Arbor, Michigan, USA), and then aligned using MUSCLE (Edgar, 2004) and manually adjusted in MEGA v.6.0 (Tamura et al., 2013). Gaps were treated as missing data. Bayesian Inference (BI) and Maximum Likelihood (ML) analyses were conducted to reconstruct the phylogeny of Asian Isodon, using MrBayes v.3.2.6 (Ronquist et al., 2012) and RAxML-HPC2 (Stamatakis, 2014) on the Cyberinfrastructure for Phylogenetic Research Science (CIPRES) Gateway (; Miller et al., 2010), respectively. Parameters of each category of analysis followed that of Chen et al. (2019). TreeGraph 2 (Stover and Müller, 2010) was used to visualize the topology of phylogenetic trees with posterior probabilities (PP) and Bootstrap support (BS) values.

3. Results and discussion

Consistent with previous molecular phylogenetic studies (Chen et al., 2019; Yu et al., 2014; Zhong et al., 2010), three well-supported clades (Fig. 1; Clades Ⅲ) are recognized for Asian Isodon. Clade Ⅲ contains ca. 80% of the species, but relationships within the clade are poorly resolved. Within Clade Ⅲ, a moderately supported subclade Clade Ⅲa (Fig. 1; BI-PP = 0.99/ML-BS = 72%) can be recognized, with most of the species having a Sino-Japanese distribution, as opposed to the remaining species of Clade Ⅲ that are predominantly distributed in the HHM region. The two individuals of the new species group together but with moderate support (Fig. 1; BI-PP = 0.94/ML-BS = 73%), which may partially result from our failure in obtaining the ITS sequence of the individual from Guangdong. The new species is further recovered in Clade Ⅲa. All species of this clade are perennial herbs, most of which are characterized with glandular or glandular and puberulent mericarps (Chen, 2017). One species that has glandular and puberulent mericarps but is not recovered in Clade Ⅲa is Isodon trichocarpus (Maxim.) Kudô, a species endemic to Japan.

Fig. 1 Phylogenetic placement of Isodon brevipedunculatus based on Maximum Likelihood analysis of the combined nuclear (ITS and ETS) dataset. Support values ≥ 0.90 PP or 50% BS are displayed on the branches following the order BI-PP/ML-BS ("*" indicates a support value of 100% and "-" indicates a PP < 0.90). Multiple accessions of the same species are numbered according to Appendix A.

Although the relationships between Isodon brevipedunculatus and other species of Clade Ⅲa are not resolved, I. brevipedunculatus is united morphologically with Isodon amethystoides (Benth.) H. Hara, Isodon excisus (Maxim.) Kudô, Isodon inflexus (Thunb.) Kudô, and Isodon bifidocalyx (Dunn) H. Hara by having densely glandular mericarps. Morphologically and geographically, the new species is most closely related to I. amethystoides and I. bifidocalyx (Fig. 2, Fig. 3, Fig. 4; Appendix B).

Fig. 2 Isodon brevipedunculatus. (A) habit; (B) flower; (C) dissected calyx; (D) dissected corolla; (E) pistil; (F) mericarp. Drawn by L. Wang.

Fig. 3 Isodon brevipedunculatus (from the type locality). (A) habit; (B) leaves; (C, D) panicles; (E) inflorescence; (F, G) infructescences; (H, I) flowers; (J) mericarps. Photographed by Y.P. Chen.

Fig. 4 Distribution of Isodon amethystoides, I. bifidocalyx, and I. brevipedunculatus.

Both Isodon brevipedunculatus and I. amethystoides have slightly 2-lipped flowering calyces with subequal teeth and erect fruiting calyces. The most noteworthy difference between the two species is the length of peduncles, which are 1–2 mm long in I. brevipedunculatus, but 1–4 cm long in I. amethystoides (Table 1). Meanwhile, laminae of I. amethystoides are usually lanceolate, whereas those of I. brevipedunculatus are ovate to broadly ovate; cymes are 3–7-flowered in the new species, but generally have more flowers per cyme (7–15-flowered) in I. amethystoides (Table 1).

Table 1 Morphological comparisons of Isodon amethystoides, I. bifidocalyx, and I. brevipedunculatus.
Character I. amethystoides I. bifidocalyx I. brevipedunculatus
Lamina lanceolate to ovate, densely pubescent to subglabrous ovate to broadly ovate, subglabrous ovate to broadly ovate, densely pubescent
Cyme 7–15-flowered 3–5-flowered 3–7-flowered
Peduncle 1–4 cm long 2–4 mm long 1–2 mm long
Flowering calyx pubescent to subglabrous, and densely glandular outside, slightly 2-lipped to 1/3 its length, teeth subequal densely glandular puberulent and glandular outside, strongly 2-lipped to 1/2 its length, teeth unequal densely pubescent and glandular outside, slightly 2-lipped to 1/3 its length, teeth subequal
Fruiting calyx erect declinate erect
Corolla ca. 6 mm long ca. 8 mm long ca. 4 mm long

Though Isodon brevipedunculatus resembles I. bifidocalyx in the ovate to broadly ovate laminae and narrow panicles (short peduncles), they can readily be distinguished by lamina indumentum, calyx morphology, and corolla length (Table 1). The new species is characterized by having densely pubescent laminae and inflorescences, while I. bifidocalyx has subglabrous laminae and densely glandular puberulent inflorescences. I. bifidocalyx also differs from I. brevipedunculatus in its strongly 2-lipped flowering calyces with unequal teeth and declinate fruiting calyces. Moreover, corollas of I. bifidocalyx are about 8 mm long, nearly twice the length of those of I. brevipedunculatus.

4. Taxonomic treatment

Isodon brevipedunculatus Y.P. Chen & C.L. Xiang, sp. nov. (Fig. 2, Fig. 3).

Type: CHINA. Guangdong, Lianshan County, Taibao Town, Dawu Mountain, in Chinese fir forest, 24°45′34″N, 112°9′40″E, alt. 690 m, 25 Oct. 2019, Y.P. Chen & Y. Zhao EM1381 (holotype: KUN!; isotypes: A!, K!, KUN!, P!, PE!, W!).

4.1. Diagnosis

The new species is morphologically similar to Isodon amethystoides and I. bifidocalyx, but differs from the former in its broadly ovate to ovate laminae (vs. ovate to lanceolate), 3–7-flowered cymes (vs. 7–15-flowered), and 1–2 mm long peduncles (vs. 1–4 cm long), and differs from the latter in having densely pubescent laminae (vs. subglabrous), flowering calyces slightly 2-lipped to 1/3 of their length with teeth subequal (vs. strongly 2-lipped to 1/2 their length with teeth unequal), erect fruiting calyces (vs. declinate), and corollas ca. 4 mm long (vs. ca. 8 mm long).

4.2. Description

Perennial herbs 50–150 cm tall. Rhizomes woody, tuberose. Stems erect, leafless at base, 4-angled, densely pubescent; internodes 5–9 cm long. Leaves opposite; lamina ovate to broadly ovate, papery, 5–12 × 3–6 cm, apex acute, margin crenate, base cuneate to rounded, adaxially dark green, pubescent, abaxially light green, densely pubescent, with colorless glands, lateral veins 4–5-paired; petioles 1–2 cm long. Panicles terminal and axillary, to 20 cm long; cymes 3–7-flowered, densely pubescent and glandular; peduncles and pedicels 1–2 mm long; floral leaves ovate, gradually reduced toward apex; bracts broadly ovate, sessile or subsessile, 5–10 mm long; bracteole linear, ca. 1 mm long. Calyx campanulate, ca. 2 mm long, 10-veined, densely pubescent and glandular outside, slightly 2-lipped to 1/3 as long as calyx; teeth 5, subequal, triangular, apex acute, fruiting calyx dilated to ca. 4 mm long, erect, slightly curved, broadly campanulate. Corolla white, ca. 4 mm long, pubescent and glandular outside; tube ca. 2 mm long, ca. 1.5 mm in diameter, saccate abaxially near base; apex 2-lipped, posterior lip 4-cleft, bluish purple at middle, lobes reflexed, ca. 1 mm long, anterior lip entire, suborbicular, concave, ca. 2 mm long. Stamens 4, included, inserted at base of corolla tube, filaments pubescent. Style included, apex slightly 2-cleft, ovaries glandular. Mericarps 4, yellowish brown, broadly ovoid, ca. 1.6 × 1.4 mm, densely glandular.


Flowering from August to November, fruiting from September to December.

Distribution and habitat

Isodon brevipedunculatus is currently known from Guangdong Province and Hunan Province in southern China (Fig. 4). It can be found in forests or on grassy slopes at altitudes of 600–1250 m.


The specific epithet refers to the short peduncles of the new species, as compared to one of the most similar species, Isodon amethystoides.

Chinese name

Duan Geng Xiang Cha Cai (短梗香茶菜).

Additional specimens examined

CHINA. Guangdong: Lianshan County, Taibao Town, Dawu Mountain, 25 Oct. 1999, H.G. Ye et al. 2532 (IBSC). Hunan: Guidong County, Zhaiqian Town, Fangcun Village, Zhulongli, in the forest, alt. 1227 m, 1 Oct. 2019, C.Z. Huang GD0074 (CSFI); Xinning County, Ma-Ling-Tung, on the grassy slope, alt. 600 m, 9 Sept. 1935, C.S. Fan & Y.Y. Li 458 (BM, LE, NAS).

Author contributions

YPC, CZH, and YZ first discovered the new species in the field and collected the material. YPC carried out the molecular experiment and analyzed the data. YPC and CLX wrote the manuscript. All authors contributed to the revision of the manuscript.

Declaration of Competing Interest

All the authors declare that there is no conflict of interest.


We would like to thank the staff of the following herbaria for their valuable help in research facilities: BM, CDBI, E, HIB, IBK, IBSC, K, KUN, KYO, LE, MW, NAS, PE, SZ, TI. Thanks are also given to Ms. Ling Wang from the Kunming Institute of Botany for her line drawing of the new species and Dr. Bryan T. Drew from the University of Nebraska for improving the English. Our manuscript also benefitted greatly from the constructive comments of two anonymous reviewers. This work was supported by the National Natural Science Foundation of China (Grant no. 31670197) and the CAS "Light of West China" Program, the Special Funds for the Young Scholars of Taxonomy of the Chinese Academy of Sciences (Grant no. ZSBR-006), the "Ten Thousand Talents Program of Yunnan" (YNWR-QNBJ-2018-279), and the "Yunnan Fundamental Research Projects" (2019FI009).

Appendix A. Sequence information for all samples used in the present study. Vouchers are only provided for samples newly collected here. Sequences newly generated in this study are marked in bold. "/" indicates missing data. All voucher specimens are deposited in the Herbarium of Kunming Institute of Botany (KUN).
Taxon Voucher/Source ITS ETS
Isodon albopilosus (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MG232833 MG232738
Isodon alborubrus (C.Y. Wu) H. Hara Chen et al. (2019) MG232741 MG232650
Isodon amethystoides (Benth.) H. Hara Chen et al. (2019) MG232762 MG232669
Isodon angustifolius (Dunn) Kudô Chen et al. (2019) MG232803 MG232709
Isodon anisochilus (C.Y. Wu) H. Hara Chen et al. (2019) MG232789 MG232695
Isodon atroruber R.A. Clement Chen et al. (2019) MG232766 MG232673
Isodon aurantiacus Y.P. Chen & C.L. Xiang Chen et al. (2019) MG232764 MG232671
Isodon barbeyanus (H. Lév.) H.W. Li Chen et al. (2019) MG232790 MG232696
Isodon bifidocalyx (Dunn) H. Hara Chen et al. (2019) MG232744 MG232653
Isodon brachythyrsus (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MG232776 MG232682
Isodon brevicalcaratus (C.Y. Wu & H.W. Li) H. Hara Y.P. Chen et al. EM1363 MT603971 MT614332
Isodon brevipedunculatus sp. nov. 1 Y.P. Chen et al. EM1381 / MT614331
Isodon brevipedunculatus sp. nov. 2 C.Z. Huang GD0074 MT603978 MT614339
Isodon bulleyanus (Diels) Kudô Chen et al. (2019) MG232798 MG232704
Isodon calcicolus (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232795 MG232701
Isodon coetsa (Buch.-Ham. ex D. Don) Kudô var. coetsa 1 Chen et al. (2019) MG232756 MG232664
Isodon coetsa (Buch.-Ham. ex D. Don) Kudô var. coetsa 2 Chen et al. (2019) MH557903 MH557887
Isodon coetsa var. cavaleriei (H. Lévl.) H.W. Li Chen et al. (2019) MG232759 MG232666
Isodon dawoensis (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232804 MG232710
Isodon delavayi C.L. Xiang & Y.P. Chen Chen et al. (2019) MG232768 MG232674
Isodon effusus (Maxim.) H. Hara Chen et al. (2019) MH557911 MH557896
Isodon enanderianus (Hand.-Mazz.) H.W. Li Chen et al. (2019) MG232740 MG232649
Isodon eriocalyx (Dunn) Kudô Chen et al. (2019) MG232805 MG232711
Isodon excisoides (Y.Z. Sun) H. Hara Chen et al. (2019) MG232806 MG232712
Isodon excisus (Maxim.) Kudô Y.P. Chen et al. EM218 MT603972 MT614333
Isodon flabelliformis (C.Y. Wu) H. Hara Chen et al. (2019) MG232771 MG232677
Isodon flavidus (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232780 MG232686
Isodon flexicaulis (C.Y. Wu & H.W. Li) H. Hara Y.P. Chen et al. EM673 MT603977 MT614338
Isodon forrestii (Diels) Kudô Chen et al. (2019) MG232810 MG232716
Isodon gibbosus (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MH557901 MH557885
Isodon glutinosus (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MG232828 MG232733
Isodon grandifolius (Hand.-Mazz.) H. Hara var. grandifolius Chen et al. (2019) MG232801 MG232707
Isodon grandifolius var. atuntzeensis (C.Y. Wu) H.W. Li Chen et al. (2019) MG232812 MG232718
Isodon hirtellus (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232813 MG232719
Isodon hispidus (Benth.) Murata Chen et al. (2019) MG232750 MG232658
Isodon hsiwenii Y.P. Chen & C.L. Xiang Chen et al. (2019) MG232770 MG232676
Isodon inflexus (Thunb.) Kudô Chen et al. (2019) MG232814 MG232720
Isodon interruptus (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MG232781 MG232687
Isodon irroratus (Forrest ex Diels) Kudô Chen et al. (2019) MG232779 MG232685
Isodon japonicus (Burm. f.) H. Hara var. japonicus 1 Chen et al. (2019) MG232783 MG232688
Isodon japonicus (Burm. f.) H. Hara var. japonicus 2 Chen et al. (2019) MH557910 MH557895
Isodon japonicus var. glaucocalyx (Maxim.) H.W. Li Chen et al. (2019) MG232818 MG232723
Isodon kangtingensis (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MG232819 MG232724
Isodon leucophyllus (Dunn) Kudô Chen et al. (2019) MG232821 MG232726
Isodon longitubus (Miq.) Kudô Chen et al. (2019) MH557912 MH557898
Isodon lophanthoides (Buch.-Ham. ex D.Don) H. Hara var. lophanthoides 1 Chen et al. (2019) MG232758 MG232665
Isodon lophanthoides (Buch.-Ham. ex D.Don) H. Hara var. lophanthoides 2 Chen et al. (2019) MH557907 MH557892
Isodon lophanthoides (Buch.-Ham. ex D.Don) H. Hara var. lophanthoides 3 Chen et al. (2019) MH557906 MH557890
Isodon lophanthoides var. graciliflorus (Benth.) H. Hara Chen et al. (2019) MG232761 MG232668
Isodon loxothyrsus (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232823 MG232728
Isodon macrophyllus (Migo) H. Hara Chen et al. (2019) MG232742 MG232651
Isodon megathyrsus (Diels) H. Hara Chen et al. (2019) MG232800 MG232706
Isodon mucronatus (C.Y. Wu & H.W. Li) H. Hara Y.P. Chen et al. EM676 MT603968 MT614328
Isodon muliensis (W.W. Sm.) Kudô Y.P. Chen et al. EM701 MT603969 MT614329
Isodon nervosus (Hemsl.) Kudô Y.P. Chen et al. EM444 MT603973 MT614334
Isodon oreophilus (Diels) A.J. Paton & Ryding Chen et al. (2019) MG232825 MG232730
Isodon oresbius (W.W. Sm.) Kudô Chen et al. (2019) MG232827 MG232732
Isodon parvifolius (Batalin) H. Hara Chen et al. (2019) MG232777 MG232683
Isodon pharicus (Prain) Murata Chen et al. (2019) MG232817 MG232722
Isodon phyllopodus (Diels) Kudô Chen et al. (2019) MG232799 MG232705
Isodon phyllostachys (Diels) Kudô Chen et al. (2019) MG232785 MG232690
Isodon pleiophyllus (Diels) Kudô Chen et al. (2019) MG232830 MG232735
Isodon polystachys (Y.Z. Sun) H. Hara Chen et al. (2019) MG232802 MG232708
Isodon pseudo-irroratus (C.Y. Wu) H. Hara Chen et al. (2019) MG232775 MG232681
Isodon racemosus (Hemsl.) Murata Chen et al. (2019) MG232745 MG232654
Isodon rosthornii (Diels) Kudô Chen et al. (2019) MG232749 MG232657
Isodon rubescens (Hemsl.) H. Hara Chen et al. (2019) MG232760 MG232667
Isodon rugosiformis (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232778 MG232684
Isodon rugosus (Wall. ex Benth.) Codd C. Liu et al. 18CS17466 MT603975 MT614336
Isodon scoparius (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MG232835 MG232739
Isodon scrophularioides (Wall. ex Benth.) Murata Y.P. Chen et al. EM1224 MT603970 MT614330
Isodon sculponeatus (Vaniot) Kudô Chen et al. (2019) MG232791 MG232697
Isodon secundiflorus (C.Y. Wu) H. Hara Y.P. Chen et al. EM667 MT603976 MT614337
Isodon serra (Maxim.) Kudô Chen et al. (2019) MG232743 MG232652
Isodon setschwanensis (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232824 MG232729
Isodon silvaticus (C.Y. Wu & H.W. Li) H.W. Li C.L. Xiang et al.1601 MT603974 MT614335
Isodon smithianus (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232816 MG232721
Isodon taliensis (C.Y. Wu) H. Hara Chen et al. (2019) MG232787 MG232692
Isodon tenuifolius (W.W. Sm.) Kudô Chen et al. (2019) MG232773 MG232679
Isodon ternifolius (D.Don) Kudô 1 Chen et al. (2019) MG232786 MG232691
Isodon ternifolius (D.Don) Kudô 2 Chen et al. (2019) MH557905 MH557889
Isodon trichocarpus (Maxim.) Kudô Chen et al. (2019) MH557909 MH557894
Isodon villosus Y.P. Chen & H. Peng Chen et al. (2019) MG232754 MG232662
Isodon walkeri (Arn.) H. Hara Chen et al. (2019) MG232755 MG232663
Isodon wardii (Marq. & Airy Shaw) H. Hara Chen et al. (2019) MG232763 MG232670
Isodon weisiensis (C.Y. Wu) H. Hara Chen et al. (2019) MG232807 MG232713
Isodon wikstroemioides (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232811 MG232717
Isodon wui C.L. Xiang & E.D. Liu Chen et al. (2019) MG232769 MG232675
Isodon xerophilus (C.Y. Wu & H.W. Li) H. Hara Chen et al. (2019) MG232747 MG232655
Isodon yuennanensis (Hand.-Mazz.) H. Hara Chen et al. (2019) MG232808 MG232714
Coleus forskohlii (Willd.) Briq. Chen et al. (2019) MG232788 MG232693
Coleus xanthanthus C.Y. Wu & Y.C. Huang Chen et al. (2019) MN116780 MN116786
Hanceola exserta Y.Z. Sun Chen et al. (2019) MN116776 MN116783
Hanceola sinensis (Hemsl.) Kudô Zhong et al. (2010); Chen et al., (2016) FJ593353 KT210227
Lavandula dentata L. Y.P. Chen s.n. / MT614340
Mesosphaerum suaveolens (L.) Kuntze Chen et al. (2019) MN116777 MN116784
Ocimum basilicum L. Walker and Sytsma (2007); Chen et al. (2016) DQ667240 KT210226
Siphocranion macranthum (Hook. f.) C.Y. Wu Chen et al. (2019) MN116781 MN116787
Siphocranion nudipes (Hemsl.) Kudô Chen et al. (2019) MN116782 MN116788
Appendix B. List of examined specimens of Isodon amethystoides and I. bifidocalyx.

Specimens of I. amethystoides examined:

CHINA. Anhui: Hefei, Courtois 6058 (NAS), E China Workstation 3771 (NAS, PE); Jingde, Courtois 12529 (NAS); Tongcheng, Courtois 4071 (NAS); Precise locality not known, Courtois 6221 (NAS), R.C. Ching 8968 (NAS). Fujian: Dehua, P.C. Tsoong 114 (PE); Guangze, Xiamen Univ. Exped. to Wuyishan 800874 (AU); Jianyang, Wuyishan Exped. 820081 (NAS); Jiangle, Longxishan Exped. 1847, 1909, 3089, 3135 (PE); Liancheng, R. Lin 3257 (PE), 3747 (PE); Nanjing, C.J. Zeng 80 (AU), P. Lin 917, 960 (AU), Xiamen Univ. Exped. 951 (AU); Shanghang, Xiamen Univ. Exped. to Meihuashan 547, 626 (AU); Wuyishan, Wuyishan Exped. 469, 470 (KUN); Precise locality not known, R. Lin 3589 (PE), X.Q. Wang 82216 (NAS). Guangdong: Dongguan, S.Y. Lau 346 (SYS); Guangzhou, S.B. Guo W.217 (IBSC); Huaiji, W.T. Tsang 22761 (IBK, IBSC, SYS); Shenzhen, Shenzhen Exped. 356, 405, 1591, 1651 (PE); Wengyuan, X.Q. Liu 24353 (IBK, IBSC); Precise locality not known, W.T. Tsang 31360 (IBSC, SYS). Guangxi: Cangwu, Cangwu Exped. 7-098 (GXMI), X.F. Wu 12016 (GXMI, KUN); Cenxi, Cenxi Exped. 7-110, 7-402 (GXMI); Gongcheng, Y.X. Feng 6-5276 (GXMI); Guiping, N.K. Liang 15945 (GXMI); Hezhou, Hexian Exped. 7-185, 7-998 (GXMI), Anonymous 401375 (IBK); Jinxiu, D. Fang et al. 378 (GXMI); Lingui, G.Z. Li 15945 (PE); Mengshan, S.Z. Huang 15611 (GXMI); Pingnan, Y.P. Chen & L. Jiang EM283 (KUN); Xing'an, G.Z. Li & Z.X. Liao 10889 (IBK); Zhaoping, Zhaoping Exped. 7-566 (GXMI). Henan: Xinxian, Anonymous 99 (KUN, PE). Hubei: Huangpi, Liu 857 (HIB); Huanggang, Medicine Inspecting Institute s.n. (HIB); Wuchang, C.H. Qian 1675 (WUK), Medicine Inspecting Institute s.n. (HIB), J.W. Wang 2 (PE); Wuhan, Z.E. Zhao 701 (HIB); Xishui, Anonymous s.n. (HIB). Jiangsu: Nanjing, J.S. Yue 600 (NAS); Suzhou, H. Migo s.n. (NAS); Yixing, Courtois 33045 (NAS), Z.L. Ding 39 (NAS), J. Shen 663 (NAS), G.J. Song s.n. (NAS). Jiangxi: Dayu, Anonymous 1741 (LBG); Guangchang, J.S. Yue et al. 2546 (IBSC, KUN); Huichang, K.M. Hu 3254 (IBSC, KUN, LBG, PE); Longnan, D.C. Wu 781198 (PE); Yanshan, M.X. Nie 4274 (IBSC, KUN, LBG); Ruijin, K.M. Hu 3905 (IBSC, KUN, LBG, PE); Shangrao, M.X. Nie 4781 (KUN, LBG, PE); Shicheng, M.X. Nie 4658 (KUN, LBG, PE); Wuyuan, Courtois 27597, 31475 (NAS); Yihuang, Q.H. Li & C. Chen 1772 (LBG, PE); Zixi, M.X. Nie 3242 (KUN, LBG). Taiwan: Hualian, Keng & Kao 2574 (TAI), S. Suzuki 8733 (TAI), M.T. Kao 6972 (TAI), T.C. Huang 4245, 4275, 4301, 4321 (TAI); Taibei, M. Taizo 4730 (TAI), N. Fukuyama 4471 (TAI), S. Tokio 18445 (NAS, PE, TAI), M.T. Kao 2113, 6298 (TAI), C.M. Kuo 8993, 9000, 9007 (TAI), C.C. Hsu 13342, 5564, 5565 (TAI); Taidong, S. Sasaki 380480 (TAI); Yilan, N. Taizo 4730 (TAI), C.I. Peng 1643 (TAI). Hong Kong: S.Y. Lau 3241 (HK), W.J. Tutcher 8394 (HK), W.Y. Chun 7847 (SYS), N.Q. Chen 41905 (IBK, IBSC), L. Jiang JL00444 (HK). Zhejiang: Chun'an, S. Chen 2394 (NAS, PE); Hangzhou, H. Migo s.n. (NAS), Oliver 90, 812 (NAS), J.L. Chu 162 (NAS), S.Y. Zhang 1342 (HHBG, NAS, PE), 1551 (HHBG, NAS, PE), 2720 (HHBG, PE), P. L. Zhu 105 (PE), Anonymous 1032 (HHBG); Jiande, S. Chen 2094 (PE); Jinyun, K.K. Tsoong 833 (PE); Jingning, Anonymous 3641 (NAS); Lishui, S.Y. Zhang 6398 (PE), Anonymous 6015 (NAS); Lin'an, H. Migo s.n. (NAS), Y.P. Chen & Q.R. Zhao EM039 (KUN), Y.Y. Ho 260 (IBSC, WUK), 716 (NAS), 849 (HHBG, IBSC, WUK), 869 (HHBG, IBSC), 25217 (HHBG), 25299 (NAS, PE), 25585 (HHBG, NAS), T.N. Liou 274 (PE), Y.H. Liu 1329 (NAS), Zhejiang Plant Resour. Exped. 29544 (NAS), Anonymous 770 (IBSC, KUN, PE); Linhai, H. Migo s.n. (NAS); Longquan, R.H. Shan 5677 (NAS, PE), Y.Y. Ho 3110 (NAS), 3114 (PE), T.S. Wang et al. 5566 (NAS), S.Y. Zhang 22829 (HHBG, NAS), Zhejiang Exped. 8449 (NAS), D.X. Zuo 21657 (HHBG, NAS), 22121 (NAS), 22904 (HHBG, NAS), Anonymous 5066 (NAS); Ningbo, S. Chen 4301 (PE), Y.Y. Ho 643 (PE), P.C. Tsoong 1081 (PE); Pingyang, Anonymous 4444, 24884 (NAS); Qingyuan, K.K. Tsoong 833 (PE); Rui'an, Y.Y. Ho 1504 (PE); Taishun, Zhejiang Exped. 8340 (NAS), D.X. Zuo et al. 23574 (NAS); Tiantai, S. Chen 3802 (PE), Y.L. Keng 1080 (NAS, PE), Hangzhou Bot. Garden Herb. 2697 (HHBG), Y.Y. Ho 27863 (NAS), S.Y. Zhang 28327 (NAS), Anonymous 1038 (NAS); Wenling, Hangzhou Bot. Garden Herb. 4083 (PE); Yunhe, S. Chen 672 (PE), Y.Y. Ho 3623 (NAS, PE), Anonymous 4001 (NAS).

Specimens of I. bifidocalyx examined:

CHINA. Anhui: Huangshan, Anonymous 4065 (NAS); Qingyang, E China Workstation 5914 (NAS, PE); Yixian, M. Liu et al. A130122 (PE). Guangdong: Renhua, L. Deng 7208 (IBSC, KUN, PE, SZ). Hunan: Nanxian, Y. Liu 334 (NAS, PE); Wugang, C.L. Xiang et al. 856, 866, 869 (KUN); Xinning, C.S. Fan & Y.Y. Li 458 (NAS); Yizhang, S.Q. Chen 2600 (IBK). Jiangxi: Binhai, S.R. Zhang 467 (NAS). Jiangxi: Guangchang, Q.M. Hu 5383 (IBSC, KUN); Guixi, M.X. Nie & S.S. Lai 3802 (PE); Jiujiang, H. Migo s.n. (NAS), H.C. Cheo 269 (NAS), K.J. Guan 74562 (PE), Y. Tsiang 10728 (NAS), M.X. Nie & S.R. Chen 7631 (LBG), C.M. Tan 95694 (HIB, IBSC, NAS, PE), M.J. Wang 978 (LBG, NAS, PE), 1076 (NAS, PE), 2190 (NAS), W.C. Cheng 5730 (PE), Y. Zhou 913 (LBG); Yanshan, M.X. Nie 4560 (PE); Suichuan, J.S. Yue et al. 4294 (IBSC, KUN); Wuyuan, Y. Tchong 27435 (NAS), R.C. Ching 8993 (PE); Xiushui, Y.Q. Miao & L.X. Li TanCM1257 (KUN). Zhejiang: Hangzhou, Y.Y. Ho 26289 (HHBG, IBSC, NAS), 26738 (NAS); Jiande, S. Chen 1965 (PE); Kaihua, M.L. Yu 26229 (NAS); Lin'an, Y.P. Chen & Q.R. Zhao EM040 (KUN), Y.Y. Ho 438 (HHBG, NAS), 726 (HHBG), 1868 (NAS), 25622 (HHBG, NAS), L.S. Liu et al. 79305 (NAS), T.S. Wang et al. 7771 (NAS), K.K. Tsoong D399 (PE), Anonymous 25683 (HHBG, PE, SZ); Longquan, Y.Y. Ho 3270 (PE), Anonymous 22516 (HHBG, NAS); Yuhang, S. Chen 2459 (PE).

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