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Research Article
Morphology and molecules support the new monotypic genus Parainvolucrella (Rubiaceae) from Asia
expand article infoYi-Da Xu§, Ming-Deng Yuan§, Rui-Jiang Wang§
‡ University of Chinese Academy of Sciences, Beijing, China
§ South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
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Abstract

Parainvolucrella R.J. Wang, a new monotypic genus for P. scabra (Wall. ex Kurz) M.D.Yuan & R.J.Wang, new combination, is segregated from the Hedyotis-Oldenlandia complex, based on morphological and molecular evidence. Phylogenetically, the new genus is sister to Scleromitrion, from which it differs by a combination of morphological characters: herbaceous habit, terminal inflorescence with subtended leaves, heterostylous flowers, indehiscent fruits and pollen with double microreticulate tectum. A key to the genera of the Hedyotis-Oldenlandia complex in China is provided for further identification.

Keywords

new combination, palynology, Parainvolucrella, Scleromitrion, taxonomy

Introduction

As one of the largest species groups of the family Rubiaceae, the Hedyotis-Oldenlandia complex contains hundreds of species distributed in the tropical and subtropical region worldwide. Due to morphological intermediacy and homoplasy, systematic studies in herbaceous Rubiaceae are very difficult (Gibbons 2020). The generic delimitation within this complex is complicated and controversial (Neupane et al. 2015) and historically disputed. The commonly shared morphological characters, such as four petals and calyx lobes, 2-celled ovaries with numerous ovules on axile placenta and capsular fruits made some studies treat this complex as one genus, Hedyotis L., in a broad sense (Lamarck 1792; Fosberg and Sachet 1991; Dutta and Deb 2004; Chen and Taylor 2011). Whereas, morphological differences in habit, inflorescence position, homo- or heterostylous flowers, dehiscent or indehiscent fruits, as well as the shape and ornamentation of seeds and pollen, provide unquestionable evidence to separate this complex into several small genera (Bremekamp 1952; Terrell et al. 1986; Terrell and Robinson 2003). Recent phylogenetic analyses, based on multiple nuclear and chloroplast DNA markers, revealed that this complex was polyphyletic and supported its subdivision into small genera (Groeninckx et al. 2009; Neupane et al. 2009; Guo et al. 2013; Wikström et al. 2013; Neupane et al. 2015; Gibbons 2020). Then the Hedyotis species in China fall into the following genera of Debia Neupane & N.Wikstr., Dimetia (Wight & Arn.) Meisn., Edrastima Raf., Hedyotis, Involucrella (Benth. & Hook.f.) Neupane & N.Wikstr., Leptopetalum Hook. & Arn., Oldenlandia L. and Scleromitrion (Wight & Arn.) Meisn. (Neupane et al. 2015; Wang 2018).

During our field investigation in Guangxi Zhuang Autonomous Region, we came across the species Hedyotis scabra Wall. ex Kurz, not recorded previously in China (Wei 2018), in bamboo forest nearby the Nonggang National Nature Reserve. This species has arbitrarily been treated as Scleromitrion scabrum (Wall. ex Kurz) Neupane & N.Wikstr. with insufficient morphological and molecular evidence (Neupane et al. 2015). Morphologically, it is similar to Involucrella coronaria (Kurz) Neupane & N.Wikstr. for its terminal inflorescence subtended by four involucral leaves. Our subsequent morphological comparison and phylogenetic analysis, based on multiple DNA markers, support that this species represents a new genus.

Materials and methods

Morphological characters of Hedyotis scabra were scored from living materials and dried specimens. All vouchers which we collected were deposited at the herbarium of South China Botanical Garden, Chinese Academy of Sciences (IBSC). Pollen and seeds were observed using scanning electron microscopy (JSM-6360LV) under 15.00 kV accelerating voltage. Pollen terminology for description followed Punt et al. (2007).

Methods of DNA extraction and PCRs followed Guo et al. (2011). Sequences of all taxa were downloaded from GenBank for molecular phylogenetic analysis, except for the newly added Hedyotis hainanensis, H. ovata, and three samples of Hedyotis scabra (Table 1). Geneious v.11.0.3 (Kearse et al. 2012) was used for sequence alignment and MrModeltest 2.0 was applied for selecting the best-fit nucleotide substitution model (GTR+G+I) on the basis of the AIC criterion (Nylander 2004). Bayesian Inference (BI) was performed using MrBayes v.3.2.7 (Ronquist et al. 2012), with a calculation of posterior probabilities (PP) to each clade. The bootstrap (BS) values were obtained by IQ-TREE v. 2.0 (Nguyen et al. 2015) for Maximum Likelihood analyses based on the best-fit nucleotide substitution model (GTR+F+R3) selected by ModelFinder (Kalyaanamoorthy et al. 2017).

Table 1.

Taxa, vouchers, localities and GenBank accession numbers of ITS, petD, rps16, trnH-psbA and trnL-F sequences for phylogenetic analysis.

Taxon Voucher (herbarium) ITS petD rps16 trnH-psbA trnL-F
Debia ovatifolia (Cav.) Neupane & N. Wikstr. China: Xing Guo & Ping Yang 20-1 (IBSC) JF699940 JF700090 JX111309 JF699795 JX111382
Dentella repens J.R. Forst. & G. Forst. Australia: Andersson 2262 (GB) AM939440 EU557693 AF333370 / EU543091
Dimetia ampliflora (Hance) Neupane & N. Wikstr. China: Ruijiang Wang et al. 1147 (IBSC) JX111198 JX111086 JX111242 JX111161 JX111317
Dimetia auricularia (L.) R.J. Wang China: Ruijiang Wang & Yiding Gao 1185 (IBSC) JF699904 JF700053 JX111298 JF699765 JX111372
Dimetia capitellata (Wall. ex G. Don) Neupane & N. Wikstr. var. capitellata China: Xiangxu Huang et al. GBOWS1278 (IBSC) JX111201 JX111089 JX111250 JX111164 JX111327
Dimetia scandens (Roxb.) R.J. Wang China: Guo Xing & Ping Yang 10 (IBSC) JF699949 JF700099 / JF699804 /
Edrastima trinervia (Retz.) Neupane & N. Wikstr. Sri Lanka: F. Fagerlind 4338 (S) HE657769 HE657652 HE649907 / /
Hedyotis acutangula Champ. ex Benth. China: Ruijiang Wang HA-02 (IBSC) JX111197 JX111085 JX111241 JX111160 JX111316
Hedyotis cantoniensis F.C. How ex W.C. Ko China: Ruijiang Wang et al. 1250 (IBSC) JF976484 JF700061 JX111247 JF699773 JX111322
Hedyotis caudatifolia Merr. & F.P. Metcalf China: Ruijiang Wang et al. 1269 (IBSC) JF699916 JF700065 JX111256 JF699777 JX111329
Hedyotis effusa Hance China: Ruijiang Wang et al. 1268_1 (IBSC) JF699933 JF700083 JX111262 JF699790 JX111335
Hedyotis hainanensis (Chun) W.C. Ko China: Guobing Jiang & Xinxin Zhou 1121 (IBSC) MZ326000* MZ403798* MZ343047* MZ403808* MZ403794*
Hedyotis ovata Thunb. ex Maxim. China: Guobin Jiang et al. 1508 (IBSC) MZ326003* MZ403799* MZ343053* MZ403807* MZ403793*
Hedyotis shenzhenensis Tao Chen China: Ruijiang Wang et al. 1262-1 (IBSC) JF976502 JF700101 JX111276 JF699805 JX111350
Hedyotis uncinella Hook. & Arn. China: Ruijiang Wang 1217 (IBSC) JF699963 JF700113 JX111282 JF699814 JX111356
Involucrella chereevensis (Pierre ex Pit.) Neupane & N. Wikstr. Thailand: Suphuntee 799 (ODU) KP994258 KR005743 KR005803 / /
Involucrella coronaria (Kurz) Neupane & N. Wikstr. China: Xing Guo & Ping Yang 22-1 (IBSC) JX111218 JX111104 JX111270 JX111177 JX111344
Leptopetalum biflorum (L.) Neupane & N. Wikstr. Singapore: Ruijiang Wang SIN03 (IBSC) JX111238 JX111120 JX111302 JX111192 JX111376
Leptopetalum pteritum (Blume) Neupane & N. Wikstr. China: Ruijiang Wang 1478 (IBSC) JF699944 JF700094 / JF699799 /
Oldenlandia capensis L. f. var. capensis Zambia: Dessein et al. 843 (BR) AM939496 EU557737 EU543048 / EU543133
Oldenlandia corymbosa L. var. corymbosa Singapore: Ruijiang Wang SIN02 (IBSC) JX111239 JX111121 JX111306 JX111194 JX111380
Oldenlandia duemmeri S. Moore Uganda: W. H. Lewis 6018 (GH) HE657744 HE657629 HE649881 / /
Oldenlandia umbellata L. Sri Lanka: F. Fagerlind 3320 (S) HE657674 HE657569 HE649806 / /
Oldenlandia wiedemannii K.Schum. Kenya: Luke & Luke 8362 (UPS) AM939525 EU557756 EU543063 / EU543151
Parainvolucrella scabra (Wall. ex Kurz) M.D. Yuan & R.J. Wang China: Mingdeng Yuan & Yida Xu YS398_1 (IBSC) MZ326006* MZ403801* MZ343069* MZ403806* MZ403796*
Parainvolucrella scabra (Wall. ex Kurz) M.D. Yuan & R.J. Wang China: Mingdeng Yuan & Yida Xu YS398_2 (IBSC) MZ326007* MZ403802* MZ343070* MZ403805* MZ403797*
Parainvolucrella scabra (Wall. ex Kurz) M.D. Yuan & R.J. Wang China: Mingdeng Yuan & Yida Xu YS399 (IBSC) MZ326008* MZ403803* MZ343071* MZ403804* MZ403795*
Parainvolucrella scabra (Wall. ex Kurz) M.D. Yuan & R.J. Wang Thailand: Neupane 183 (ODU) KP994264 KR005751 KR005812 / /
Pentodon pentandrus Vatke Zambia: Dessein et al. 598 (BR) AM939528 EU557759 EU543066 / EU543154
Scleromitrion angustifolium (Cham. & Schltdl.) Benth. China: Xing Guo & Ping Yang 12 (IBSC) JF976506 JF700108 JX111297 JF699810 JX111370
Scleromitrion diffusum (Willd.) R.J. Wang China: Xing Guo 51 (IBSC) JF699932 JF700081 JX111308 JF699789 JX111381
Scleromitrion koanum (R.J.Wang) R.J. Wang China: Ruijiang Wang et al. 978 (IBSC) JX111215 JX111101 JX111267 JX111174 JX111341
Scleromitrion pinifolium (Wall. ex G.Don) R.J. Wang China: Ruijiang Wang 1231 (IBSC) JX111240 JF700094 JX111311 JX111196 JX111384

Results

Phylogenetic analysis

The phylogenetic analysis, based on nuclear ITS and four chloroplast DNA regions (petD, rps16, trnH-psbA and trnL-F), generated an almost identical tree to that of Neupane et al. (2015). It showed that all the samples of Hedyotis scabra cluster into an independent clade which is sister to Scleromitrion with robust support (PP = 1, BS = 100, Fig. 1). In addition, the morphological similar species, Involucrella coronaria, nested in the Involucrella clade (PP = 1, BS = 93, Fig. 1) and is sister to the lineage of (Debia clade + (Leptopetalum clade + (Dimetia clade + (Scleromitrion clade + H. scabra clade)))) with robust support (PP = 1, BS = 100, Fig. 1).

Figure 1. 

Phylogenetic relationships of the Hedyotis-Oldenlandia complex derived from a combined analysis of ITS and plastid petD, rps16, trnH-psbA and trnL-F. Bayesian Posterior Probability (PP ≥ 0.5) and Bootstrap values (BS ≥ 50%) are indicated above and below the branches, respectively.

Taxonomic treatment

Based on the morphological and palynological differences between Hedyotis scabra and Scleromitrion, as well as the molecular evidence, a new genus is proposed here.

Parainvolucrella R.J. Wang, gen. nov.

拟合叶耳草属 (Nǐ Hé Yè ěr Cǎo Shǔ)

Note

Annual or perennial herbs. Stem decumbent. Inflorescences terminal, congested-cymose, involucrated. Flowers heterostylous; petals 4; ovary 2-loculed, ovules many. Pollen 3-colporate; tectum double microreticulate. Fruits indehiscent. Seeds trigonous; testa reticulate.

Type

Parainvolucrella scabra (Wall. ex Kurz) M.D. Yuan & R.J. Wang (Hedyotis scabra Wall. ex Kurz)

Parainvolucrella scabra (Wall. ex Kurz) M.D. Yuan & R.J. Wang, comb. nov.

Figs 2, 3

Basionym: Hedyotis scabra Wall. ex Kurz, J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 46(2): 133, 136 (1877). Type: MYANMAR. from Martaban down to Upper Tenasserim, Wall. Cat. 880 (holotype: CAL; isotypes: G [G00436284!; G00436285!]; K [K001110148!; K001110149! K000031881!]).

Synonym: Scleromitrion scabrum (Wall. ex Kurz) Neupane & N.Wikstr., Taxon 64(2): 317 (2015)

Description

Annual or perennial herbs. Stems decumbent, ca. 1 m long, roughly angular, usually rooted at nodes; branches ascending to 30 cm high. Leaves opposite, subsessile to petiolate, petiole to 3 mm long; blades 2.0–7.0 × 1.0–3.0 cm, narrowly ovate to ovate, apex acute, base cuneate; leaf scabrid adaxially and along the veins abaxially; mid-rib depressed adaxially and prominent abaxially; secondary veins 5–6 on each side. Stipules ca. 3.0 × 2.0 mm, triangular, fimbriate with tipped colleters, excurved, pubescent abaxially. Inflorescence terminal, (2–)3–8(–12)-flowered, congested-cymose, usually subtended by 4 involucral leaves; peduncle subsessile; bracts 2–3 mm long, narrowly ovate, scabrid; bracteoles ca. 1 mm long, truncate to broadly ovate-triangular, fimbriate with tipped colleters, glabrous. Flowers heterostylous, pedicels to 0.8 mm long. Hypanthium ca. 0.8 mm long, obconic, 4 longitudinal projections against the lobes; lobes 4, ca. 1.5 × 0.4 mm long, narrowly triangular to narrowly oblong, scabrid. Corolla white, tube 1.5–2.0 mm long, glabrous abaxially and pubescent adaxially; lobes 4, 2.3–2.8 × 0.7–0.8 mm, oblong. Stamens 4, anthers 0.6–0.7 mm long. Stigma bilobed, 0.5–0.6 mm long, papillate. Longistylous flowers: stamens included, filaments adnate to the base of corolla tube, filaments ca. 2 mm long; styles ca. 4.3 mm long, exserted, included part pubescent, stigma ellipsoid. Brevistylous flowers: stamens included; filaments adnate to the base of corolla tube, filaments ca. 5.6 mm long; styles ca. 2 mm long, exserted, pubescent, stigma clavate. Fruits ca. 2.1 × 2.3 mm, subglobose, with 4 longitudinal projections when young, scabrid, indehiscent. Seeds trigonous, 0.4–0.5 mm, numerous, black; testa reticulate.

Figure 2. 

Parainvolucrella scabra (Wall. ex Kurz) M.D. Yuan & R.J. Wang A habit B leaf adaxial (left) and abaxial (right) surface C stem and stipule D infructescence with four involucral leaves E infructescence with bracts F calyx with bracteole at base G–I longistylous flower J–L brevistylous flower M, N fruits O seeds.

Figure 3. 

Seed morphology of Parainvolucrella scabra A ventral side B dorsal side C testa ornamentation.

Phenology

Flowering from July to September; fruiting from October to December.

Etymology

The generic name Parainvolucrella alludes to similarity to Involucrella coronaria in possessing terminal inflorescence subtended by four involucral leaves.

Distribution and habitat

Bangladesh, India, Myanmar, Thailand and Vietnam (Fukuoka 1970; Dutta and Deb 2004), and China (new record). Only one subpopulation including about 200 individuals was found in dense bamboo forest and at the edge of the forest nearby the Nonggang National Nature Reserve. The habitat there belongs to a tropical monsoon climate, main associated species are Dendrocalamus latiflorus Munro (Poaceae) and Centotheca lappacea (L.) Desv. (Poaceae).

Palynology

Monads, isopolar and prolate-spheroidal, with 3-colporate apertures; the tectum is double microreticulate, with a psilate suprareticulum and a microechinate infrareticulum. The pollen size is 22.2 (20.9–23.7) × 20.2 (18.3–21.8) μm with P/E value 1.10 in brevistylous flowers (Fig. 4A–C); and 20.2 (18.5–21.2) × 19.0 (16.6–20.6) μm with P/E value 1.06 in longistylous flowers (Fig. 4D–F).

Figure 4. 

Pollen morphology of Parainvolucrella scabra (A–C from Mingdeng Yuan & Yida Xu YS398, brevistylous flower D–F from Mingdeng Yuan & Yida Xu YS399, longistylous flower) A, D equatorial view B, E polar view C, F double microreticulate ornamentation of mesocolpium.

Additional specimens examined

China. Guangxi Zhuang Autonomous Region: Chongzuo City, Longzhou County, Zhubu Town, Nonggang Village, 1 Nov 1978, Nonggang Investigation Team 11263 (IBK!); same locality, 22°29'16"N, 106°56'13"E, elev. 287 m, 29 Oct 2020, Ming-Deng Yuan & Yi-Da Xu YS398, YS399 (IBSC!); same locality, 22°29'22"N, 106°56'11"E, elev. 290 m, 2 Feb 2021, Ming-Deng Yuan YS407 (IBSC!); Zhubu Town, Lenglei Village, 9 Oct 1979, Nonggang Investigation Team 20457 (GXMI!). India. India orientalis: in Bengalia circa Calcuttam, J.W.Helfer 40 (P03904580). Thailand. Kampeng: A.F.G. Kerr 6161 (SING!); Tak: Ban Musoe, 22 Jul 1973, Gen Murata et al. 16719 (P03904581).

Key to the genera of the Hedyotis-Oldenlandia complex in China

1 Decumbent or prostrate herbs or climbers 2
Erect or ascending herbs, subshrubs or shrubs 5
2 Herbs; venation triplinerved inconspicuously above base; flowers homostylous Edrastima
Herbs or climbers; pinnated venation; flowers heterostylous 3
3 Climbers Dimetia
Decumbent or prostrate herbs 4
4 Stipules triangular, fimbriate with tipped colleters; inflorescence terminal, subtended by four leaves Parainvolucrella
Stipules broadly triangular, apex spinous; inflorescence terminal or axillary, without subtended leaves Dimetia
5 Shrubs or subshrubs Hedyotis
Herbs 6
6 Inflorescence terminal, subtended by two or four leaves 7
Inflorescence terminal or axillary, without subtended leaves 8
7 Inflorescence large and loose, peduncles and pedicels long Debia
Inflorescence small and congested, peduncles and pedicels subsessile Involucrella
8 Fruits winged conspicuously or inconspicuously Leptopetalum
Fruits wingless 9
9 Herbs gracile; growing in limestone area Involucrella
Herbs robust; growing in non-limestone area 10
10 Stipules papery, hard, entire or fimbriate; flower homo- or heterostylous; fruits dehisce diplophragmously Hedyotis
Stipules membrane, fimbriate; flower homostylous; fruits dehisce loculicidally 11
11 Stamens and stigma included in corolla tube Oldenlandia
Stamens and styles exserted from corolla tube Scleromitrion

Discussion

The plant habit, stipule shape, inflorescence position, flower distyly and the dehiscent pattern of the fruits are of diagnostic significance in the different genera of the Hedyotis-Oldenlandia complex (Dutta and Deb 2004). Several successive field collections observed that the fruits of Hedyotis scabra are completely indehiscent, which was obscurely diagnosed by Hooker (1880) and incorrectly described by Dutta and Deb (2004). Hedyotis scabra differs from Scleromitrion by the terminal inflorescences with involucral leaves (vs. axillary or terminal and axillary in the uppermost leaf axils in Scleromitrion), the heterostylous flowers (vs. homostylous in Scleromitrion), pollen grains tectum double microreticulate, with psilate suprareticulum and microechinate infrareticulum (vs. rugulate tectum with microechinate muri in Scleromitrion) and indehiscent fruits (vs. loculicidally dehiscent in Scleromitrion). On the other hand, Parainvolucrella scabra is similar to Involucrella coronaria with respect to their terminal inflorescence subtended by involucral leaves, heterostylous flowers and indehiscent fruits, but Parainvolucrella has decumbent habit (vs. erect or ascending in Involucrella coronaria), young fruits with 4 longitudinal projections (vs. smooth surfaces in Involucrella coronaria) and trigonous seeds with no pits on the surface (vs. ellipsoidal and 3–5 pitted seeds in Involucrella coronaria) (Table 2).

Table 2.

Morphological comparison of the Hedyotis-Oldenlandia complex distributed in China.

Taxon Habit Stipules Flowers Fruits Seeds Pollen
Debia Neupane & N. Wikstr. Annual small herbs, erect Papery, broadly triangular, fimbriate with tipped colleters Homostylous with exserted stigma and stamens Compressed globose, loculicidally dehiscent Conoidal with deeply depressed exotesta, anticlinal boundaries nearly straight or rounded 3-colporate, perforate tectum with psilate muri
Dimetia (Wight & Arn.) Meisn. Perennial herbs or subshrubs, prostrate, decumbent or climber Papery, truncate, broadly rounded or broadly triangular, spinous Heterostylous Subglobose to ellipsoidal, dehiscent diplophragmously or indehiscent Dorsiventrally flattened or trigonous, reticulate, anticlinal boundaries nearly straight 3- or 4-colporate, double microreticulate tectum with psilate suprareticulum and microechinate infrareticulum
Edrastima Raf. Annual small herbs, decumbent Membranous, truncate, fimbriate with tipped colleters Homostylous with exserted stigma and stamens Subglobose, loculicidally dehiscent Trigonous to ellipsoidal, reticulate, anticlinal boundaries nearly straight 3-colporate, microreticulate tectum with psilate muri
Hedyotis L. Perennial herbs to shrubs, erect or ascending Papery, triangular, entire to fimbriate with tipped colleters Heterostylous or rarely homostylous with exserted stigma and stamens Ellipsoidal, dehiscent diplophragmously or rarely indehiscent Dorsiventrally flattened, reticulate, anticlinal boundaries nearly straight 3- or 4-colporate, double microreticulate tectum with psilate suprareticulum and microechinate infrareticulum
Involucrella (Hook. f.) Neupane & N. Wikstr. Annual herbs, erect or ascending Papery, triangular or truncate, margin fimbriate or acicular spinous with tipped colleters Heterostylous or rarely homostylous with included stigma and stamens Hemispherical to ellipsoidal, loculicidally dehiscent or indehiscent Ellipsoidal, 3–5 pitted, anticlinal boundaries nearly straight or undulate 3- or 4-colporate, double microreticulate tectum with psilate suprareticulum and microechinate infrareticulum
Oldenlandia L. Annual small herbs, erect or ascending Membranous, flabellate or broadly rounded, fimbriate with tipped colleters Homostylous with included stigma and stamens Globose to ellipsoidal, loculicidally dehiscent Trigonous, reticulate, anticlinal boundaries nearly straight 3- or 4-colporate, microreticulate tectum with psilate muri
Parainvolucrella R.J. Wang Annual or perennial herbs, decumbent Papery, triangular, fimbriate with tipped colleters Heterostylous Subglobose, 4 longitudinal projections when young, indehiscent Trigonous, reticulate, anticlinal boundaries nearly straight 3-colporate, double microreticulate tectum with psilate suprareticulum and microechinate infrareticulum
Scleromitrion (Wight & Arn.) Meisn. Annual small herbs, erect or ascending Membranous, triangular to rounded, fimbriate with tipped colleters Homostylous with exserted stigma and stamens Subglobose, loculicidally dehiscent Trigonous to conoidal, reticulate, anticlinal boundaries nearly straight 3- or 4-colporate, rugulate tectum with microechinate muri
Leptopetalum Hook. & Arn. Annual small herbs, erect Papery, triangular or broadly triangular, fimbriate with tipped colleters Homostylous with included stigma and stamens Obconical, winged, loculicidally dehiscent Ellipsoidal with deeply depressed exotesta, anticlinal boundaries undulate 3-colporate, microreticulate tectum with psilate muri

Based on the combined nuclear (ITS, ETS) and plastid (petD, rps16) data, Neupane et al. (2015) did not provide a well-resolved phylogenetic tree to support the placement of Hedyotis scabra as sister to the remainder of Scleromitrion in the Hedyotis-Oldenlandia complex, neither did Gibbons (2020). In addition, it seemed that the morphological confliction between the H. scabra and Scleromitrion and the phylogenetic exclusion of H. scabra from Scleromitrion clade were overlooked before making the new combination by Neupane et al. (2015). Our further integrated analysis, based on the morphological incongruence and the robust phylogenetic support (BS = 100, PP = 1), based on nrITS and plastid petD, rps16, trnH-psbA and trnL-F, elucidated the taxonomic and phylogenetic confusions and thus the new monotypic genus Parainvolucrella is proposed here.

Acknowledgements

This work was supported by the General Program of National Natural Science Foundation of China (Grant no. 31770217). We are grateful to Mr. Xin-Xin Zhou for field assistance and Ms. Xiao-Ying Hu for SEM observation.

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