Corresponding author: Rui-Jiang Wang (
Academic editor: Yasen Mutafchiev
Xu Y-D, Yuan M-D, Wang R-J (2021) Morphology and molecules support the new monotypic genus
As one of the largest species groups of the family
During our field investigation in Guangxi Zhuang Autonomous Region, we came across the species
Morphological characters of
Methods of DNA extraction and PCRs followed
Taxa, vouchers, localities and GenBank accession numbers of ITS,
Taxon | Voucher (herbarium) | ITS | ||||
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China: Xing Guo & Ping Yang 20-1 ( |
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Australia: Andersson 2262 (GB) |
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China: Ruijiang Wang et al. 1147 ( |
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China: Ruijiang Wang & Yiding Gao 1185 ( |
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China: Xiangxu Huang et al. GBOWS1278 ( |
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China: Guo Xing & Ping Yang 10 ( |
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Sri Lanka: F. Fagerlind 4338 (S) |
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China: Ruijiang Wang HA-02 ( |
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China: Ruijiang Wang et al. 1250 ( |
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China: Ruijiang Wang et al. 1269 ( |
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China: Ruijiang Wang et al. 1268_1 ( |
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China: Guobing Jiang & Xinxin Zhou 1121 ( |
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China: Guobin Jiang et al. 1508 ( |
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China: Ruijiang Wang et al. 1262-1 ( |
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China: Ruijiang Wang 1217 ( |
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Thailand: Suphuntee 799 (ODU) |
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China: Xing Guo & Ping Yang 22-1 ( |
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Singapore: Ruijiang Wang SIN03 ( |
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China: Ruijiang Wang 1478 ( |
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Zambia: Dessein et al. 843 (BR) |
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Singapore: Ruijiang Wang SIN02 ( |
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Uganda: W. H. Lewis 6018 (GH) |
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Sri Lanka: F. Fagerlind 3320 (S) |
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Kenya: Luke & Luke 8362 (UPS) |
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China: Mingdeng Yuan & Yida Xu YS398_1 ( |
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China: Mingdeng Yuan & Yida Xu YS398_2 ( |
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China: Mingdeng Yuan & Yida Xu YS399 ( |
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Thailand: Neupane 183 (ODU) |
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Zambia: Dessein et al. 598 (BR) |
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China: Xing Guo & Ping Yang 12 ( |
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China: Xing Guo 51 ( |
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China: Ruijiang Wang et al. 978 ( |
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China: Ruijiang Wang 1231 ( |
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Notes: “*” indicates the newly-seqenced fragments, “/” indicates the missing data.
The phylogenetic analysis, based on nuclear ITS and four chloroplast DNA regions (
Phylogenetic relationships of the
Based on the morphological and palynological differences between
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.
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.
Seed morphology of
Flowering from July to September; fruiting from October to December.
The generic name
Bangladesh, India, Myanmar, Thailand and Vietnam (
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.
Pollen morphology of
1 | Decumbent or prostrate herbs or climbers |
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– | Erect or ascending herbs, subshrubs or shrubs |
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2 | Herbs; venation triplinerved inconspicuously above base; flowers homostylous |
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– | Herbs or climbers; pinnated venation; flowers heterostylous |
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3 | Climbers |
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– | Decumbent or prostrate herbs |
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4 | Stipules triangular, fimbriate with tipped colleters; inflorescence terminal, subtended by four leaves |
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– | Stipules broadly triangular, apex spinous; inflorescence terminal or axillary, without subtended leaves |
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5 | Shrubs or subshrubs |
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– | Herbs |
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6 | Inflorescence terminal, subtended by two or four leaves |
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– | Inflorescence terminal or axillary, without subtended leaves |
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7 | Inflorescence large and loose, peduncles and pedicels long |
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– | Inflorescence small and congested, peduncles and pedicels subsessile |
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8 | Fruits winged conspicuously or inconspicuously |
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– | Fruits wingless |
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9 | Herbs gracile; growing in limestone area |
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– | Herbs robust; growing in non-limestone area |
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10 | Stipules papery, hard, entire or fimbriate; flower homo- or heterostylous; fruits dehisce diplophragmously |
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– | Stipules membrane, fimbriate; flower homostylous; fruits dehisce loculicidally |
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11 | Stamens and stigma included in corolla tube |
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– | Stamens and styles exserted from corolla tube |
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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
Morphological comparison of the
Taxon | Habit | Stipules | Flowers | Fruits | Seeds | Pollen |
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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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 (
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.