1. Introduction

China has the richest and most diverse flora of any country in the northern hemisphere, with more than 32, 500 species of vascular plants documented from throughout its vast territory (Hong and Blackmore, 2015). In a recent report from Kew (Willis and Bachman, 2016), China was among the top three countries in the discovery and naming of new species of vascular plants published between 2006 and 2015. According to data from the International Plant Names Index (IPNI), the number of vascular plants reported as new to science from China has regularly exceeded 100 per year during that decade, with the total number being 1537 (Willis, 2017). Those numbers, however, do not account for all new names published in China during that period. Some publications dealing with Chinese vascular plants have not been included in international databases for various reasons. Some journals and books published locally in China are not readily available outside the country. The actual number of newly describe Chinese vascular plants is significantly greater than the number reported in IPNI. To supplement the international databases of plant names a regional database was needed. The Chinese Plant Names Index (CPNI) is a database of names of Chinese vascular plants that attempts to fill that gap by indexing new names and name changes that have been proposed for the Chinese flora.

The first account of new names of Chinese vascular plants was released via the worldwide web (http://cpni.ibiodiversity.net) and simultaneously printed in hard copy (Du and Ma, 2019a; 2019b). The hard copy index, covering the years 2000 through 2017, contains 10, 850 entries. The online version covering all data from 2000 to 2019, contains 11, 895 entries.

The 11, 895 names accounted for were authored by 3276 scholars. A unique entry accounts for the name of each newly described taxon and its place of publication. The entries deal with all novelties at the rank of family, genus, species, subspecies, variety, form and named hybrids. Name changes (new combinations, new names at new rank and new replacement names), new records and new synonyms, and lectotypifications and neotypifications for vascular plants reported or recorded from China are also included. Invalid and illegitimate names of Chinese vascular plants that were used during the 2000–2019 period are given in Appendix I.

The following is a summary of the CPNI for the 20 years, 2000 through 2019.

2. New taxa published each year

From 2000 through 2019, 4407 new taxa were described based on Chinese vascular plants, including 7 new families, 132 new genera (details on newly published families and genera is in Appendix II), 3543 new species, 68 new subspecies, 497 new varieties and 160 new forms. Among the 132 newly established genera, 26 were based on new species. The remaining new genera were based on previously published species in existing genera. The number of new species have regularly exceeded 177 per year for the past 20 years. The number of names below the level of species has averaged 36 per year, but fell below 20 per year in the most recent three years of the period covered. The data show that despite increased attention paid to biodiversity hotspots, a large number of undescribed species in China await discovery. Further investigation is certainly necessary.

The publication of new species supported by molecular evidence has only gradually increased since 2010 in China; only 1/5 of the species published between 2014 and 2019 were accompanied by molecular data (See more details in the supplementary file). The publication of new taxa based on molecular evidence is increasingly recognized as important supporting evidence for names published in international journals (Fig. 1).

3. Families and genera in which new taxa were described

New species published in the 20 years from 2000 through 2019 were in 172 families (according to the current molecular systematics¹) and 859 genera, covering about 55% of the families and 26% of the genera recognized in China. Statistics on the number of newly described vascular plants indicate that a large number of them were published in the well-known large families, such as Orchidaceae (89 gen., 376 sp.), Asteraceae (35 gen., 200 sp.), Poaceae (51 gen., 197 sp.), Fabaceae (28 gen., 180 sp.), Rosaceae (17 gen., 151 sp.), Ranunculaceae (12 gen., 135 sp.). The limestone areas of China, which harbor many local endemics, have been the source of many of them, especially in such families as Gesneriaceae (29 gen., 226 sp.), Urticaceae (11 gen., 193 sp.), Begoniaceae (1 gen., 80 sp.) and Balsaminaceae (1 gen., 69 sp.). The 25 families and genera with the most new species of vascular plants in China are shown in Table 1.

During those 20 years, 376 new species of Orchidaceae were published by 208 scholars, but only 12 scholars published more than 10 species. In fact, those 12 scholars published 247 new species of orchids, accounting for more than 66% of all orchids described during that period.

The use of molecular data accompanying the publication of new species of orchids was also relatively higher than in other families. Fifty three species, about 14 percent of new orchids, were published with molecular evidence compared to the 8.5 percent of all species with molecular data. Gesneriaceae also showed a greater use of molecular data.

Two hundred twenty six new species of Gesneriaceae were published by 142 scholars, but only 8 scholars published more than 10 species. Those 8 scholars published 155 new species, accounting for more than 68% of the total. Thirty seven species, about 16.3%, were published with molecular evidence, which was greater than in Orchidaceae. In difficult taxa such as Orchidaceae and Gesneriaceae, the knowledge and experience of experts is indispensable for the identification of taxa. The application of new technologies to supplement that knowledge is a welcome development.

4. The source of new taxa

More than 1164 new taxa and 230 newly recorded species were reported from Yunnan in southwest China. They represent about one third of the total and are far more than for any other province. Guangxi, Sichuan and Xizang were also important sources of new discoveries, with more than 1600 new taxa and records from these three provinces. By area, Taiwan and Hainan, two islands in southern China, have the highest density of newly discovered species. Yunnan and Guangxi also have a high density of newly described species, even though they occupy vast areas, perhaps due to the long-term attention of taxonomists to these areas; Guangxi because of its extensive limestone and Yunnan because its great diversity of habitats, which range from tropical to alpine. The number of new discoveries from Guizhou, however, was far fewer than from the neighboring provinces of Guangxi, Sichuan and Yunnan, even though Guizhou has a similar topography and climatic and also extensive karst areas. The difference may be due to fewer field studies within the province (Fig. 2).

5. Authors of new taxa

The 4382 new names and 3838 newly transferred names of Chinese vascular plants were authored by 1892 (86.7%) Chinese authors and 289 (13.3%) foreign authors. At the species level, 2633 new species, about 74.3% of all new names, were published solely by Chinese scholars; 539 new species, about 15.2%, were published solely by foreign authors; 371 new species, about 10.5%, were published by cooperation between Chinese and foreign authors. The number of botanists who published new names based on transfers was significantly less than the number who published new taxa. Eight hundred and fourteen scholars published new combinations, new names at new rank, and new replacement names. The top 25 Chinese and foreign botanists who published new taxa (with the standard abbreviation of their name and full name) are in Table 2. Chinese and foreign authors who published new combinations for Chinese vascular plants are shown in Table 3.

6. Taxonomic studies leading to name changes

Besides new taxa of vascular plants, 643 plants were discovered for the first time in China during this period. Newly published taxa and newly discovered taxa have resulted in a net increase of 252 additions per year to the flora of China. At the same time, 3562 new combinations and names at new rank, and 306 new replacement names were published. Additionally, 2349 names were reduced to synonymy under 1406 names. Synonymizing resulted in a net reduction of 50 taxa per year in the Chinese flora. The data still show an overall increase of about 200 taxa per year in the Chinese flora. Based on figures for the most recent years, there appears to be no tendency to deviate from this pattern. The findings indicate that China still has a large number of undescribed species awaiting discovery. The number of new vascular plants described worldwide has been stable at around 2000 per year for each year since 2015 (Christenhusz and Byng, 2016). New taxa based on Chinese plants therefore account for about one tenth of the worldwide total.

7. Place of publication for new names

New taxa and nomenclatural changes in China were published in 188 journals and 140 books. Among the 11, 895 entries, 9652 names, about 81.1%, were published in 4086 articles in 188 journals. The remaining 2243 entries, about 18.9%, were published in books. Among those, 1714 were published in floras and checklists, 421 in monographs and 73 in proceedings. Articles with the Chinese authors as the lead author accounted for the majority, even though most of the articles were published in English. Although 188 journals published articles on new names and name changes of Chinese vascular plants, 85% of the articles were published in 26 journals, such as Phytotaxa, Journal of Systematics and Evolution (formerly Acta Phytotaxonomica Sinica), Novon, Nordic Journal of Botany, Annales Botanici Fennici, Bulletin of Botanical Research and Journal of Tropical and Subtropical Botany (Fig. 3). Since 2008, most of the articles were published in journals monitored by the Scientific Citation Index (SCI; Anonymous, 2020) (Fig. 4).

Chinese journals represented the majority of journals in which new names were published before 2008, which was related to China's research evaluation system. The quality of journals with strict international peer review are significantly better than domestic journals. Articles in English are more convenient for an international audience. Among the journals, Phytotaxa has played a major role in accelerating the publication of new discoveries, with 507 new species from China published since its founding in 2009. Phytotaxa has published more than a quarter of the approximately 2000 species described each year worldwide and has become a major player in the dissemination of knowledge on newly described plants.

8. Invalid and illegitimate names

We examined the original literature for 7555 newly described or transferred Chinese vascular plants and discovered more than 150 names that were not validly published. Failure to designate a type specimen, lack of a Latin (or English) description or diagnosis and new transferred names unaccompanied by a reference to the basionym or replaced synonyms were the main reasons. One hundred and eight names were illegitimate because they were published as later homonyms or isonyms. The names of the 258 invalid or illegitimate names and reasons for their rejection are given in Appendix I.

The availability of two national floras published within the past 60 years (Editorial Committee of FRPS, 2004; Wu et al., 2013), and more than 40 local floras at the province level or above (Du et al., 2020), make it easier than in the past to recognize undescribed species. It is especially critical that these new taxa are discovered. Since urbanization and the resulting sprawl threaten natural habitats in China. As in the rest of the world, expanded field studies should be encouraged and supported so that the remaining undescribed plants can be found before they and their habitats are lost.

Author contributions

C. Du and J. S. Ma planned and designed the research. C. Du and S. Liao collected the original data and standardized the data, C. Du analysed the data and wrote the manuscript, J. S. Ma and Boufford revised the manuscript.

Declaration of competing interest

This article does not involve conflicts of interest.

Acknowledgements

This study was supported by the Special Fund for Scientific Research of Shanghai Landscaping & City Appearance Administrative Bureau, China (G182415), the National Specimen Information Infrastructure (2018 Special Funds), China and Shanghai Sailing Program, China (14YF1413800).

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.pld.2020.08.004.