New scientific discoveries: Plants and fungi

1Identification and Naming, Royal Botanic Gardens, Kew, UK 2Conservation Science, Royal Botanic Gardens, Kew, UK 3Biodiversity Informatics and Spatial Analysis, Royal Botanic Gardens, Kew, UK 4Vilgalys Mycology Laboratory, Department of Biology, Duke University, Durham, NC, USA 5Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN, USA 6Herbario UCH, Universidad Autónoma de Chiriquí, David, Panama 7Department of Biology, Research Group Mycology, Ghent University, Gent, Belgium 8Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, UK 9Department of Life Sciences, Imperial College London, London, UK 10Laboratory of Mycology, Institute of Botany, Academy of Sciences of the Republic of Uzbekistan, Tashkent, Uzbekistan 11Center of Excellence in Fungal Research, Mae Fah Luang University, Thailand 12Westerdijk Fungal Biodiversity Institute, Utrecht, The Netherlands 13Royal Botanic Garden Edinburgh, Edinburgh, United Kingdom 14Jardim Botânico do Rio de Janeiro, Rio de Janeiro, Brasil 15Singapore Botanic Gardens, National Parks Board, Singapore, Singapore


| INTRODUC TI ON
While some species unknown to science are already known to local communities and may have local names, scientific discovery, including scientific naming of new taxa is important because without a scientific name, a species is invisible to the world of science and the possibility of researching its ecology, applications, phylogenetic placement, and threats is greatly reduced. Above all, scientific discovery and naming (henceforth "discovery") is increasingly important for species conservation because the species which remain to be discovered are often those most likely to be at risk of extinction and giving them a name facilitates synthesis and dissemination of the available information about them, a vital first step in evaluating their extinction risk. The fungal kingdom is significantly less well studied than the plant kingdom. Currently 148,000 species of fungi are recognized (Species Fungorum, 2020), the majority in the phyla Ascomycota and Basidiomycota (BOX 1), but it is estimated that the vast majority, over 90%, of fungal species are currently unknown to science and that the total number is somewhere between 2.2 and 3.8 million (Hawksworth & Lücking, 2017).
In contrast, known land plant species have been estimated to number c. 400,000 of which c. 380,000 are vascular plants, with 370,000 belong to the largest phylum, flowering plants (Angiospermae), although these numbers are debated (Nic Lughadha et al., 2016;Nic Lughadha, Bachman, & Govaerts, 2017) and the recently completed World Checklist of Vascular Plants lists 347,298 accepted species (WCVP, 2020). A decade ago, many plant scientists considered that the vast majority of flowering plants had already been discovered, with just 10%-20% remaining to be described (Joppa, Roberts, Myers, & Pimm, 2011 ). However, the fairly steady rates of publication of new plant species in the interim suggest otherwise (Figure 1a), as do the experiences of many botanists undertaking fieldwork in the tropics. For example, Corlett (2020) suggests as many as 100,000 more plant species remain to be discovered. Giam et al. (2012)  We compare the kingdoms in terms of rates of scientific discovery, globally and in different taxonomic groups and geographic areas, and with regard to the use of DNA in discovery. We review species new to science, especially those of interest to humanity as new products, and also by life-form. We consider where future such discoveries can be expected. We recommend an urgent increase in investment in scientific discovery of plant and fungal species, while they still survive.
Priorities include more investment in training taxonomists, in building and equipping collections-based research centers for them, especially in species-rich, income-poor countries where the bulk of species as yet unknown to science are thought to occur.

K E Y W O R D S
DNA versus morphology, extinction before scientific discovery, properties of new species, rates of discovery of plants and fungi four new phyla of fungi were named in 2018, taking the total to 18 (Tedersoo et al., 2018). While new higher taxa of fungi are now com- There are several reasons why fungi are less well known than plants: They are challenging to study and many of them have cryptic lifestyles spending most of their time as hyphae, or more rarely as cells, e.g. in soil. Characters suitable for morphological classification are fewer than in plants and moreover the characters often overlap and are therefore challenging to use in classification. Also, convergent evolution is common in fungi (Willis, 2018). Finally, the diversity of the Kingdom Fungi is high while the number of mycologists compared to botanists is relatively small.
The increasing rate of fungal discovery in the past two decades is attributed to the advent of DNA studies which have become standard practice, in addition to the traditionally used morphological data, in describing new taxa. This has accelerated the discovery of new species and greatly facilitated the study of relationships. For species-level studies a single DNA marker, ITS (including two spacers ITS1 and ITS2 and the highly conserved 5.8S gene), is in many cases effective across the fungal kingdom for taxonomic purposes although in some groups other markers are needed as well. In contrast, for plants, no single marker is sufficient to distinguish species from each other across the kingdom, or indeed across flowering plants, and most species discoveries today are based solely on morphological data (E. Lucas pers. comm., D.Goyder pers. comm., I. Larridon pers. comm.). Most plant species have not been subjected to DNA studies. In fact, comprehensive sampling at generic level is still a target (PAFTOL, 2020). If it were possible to sample and analyse the DNA of plants in the same way as fungi, would species discovery be accelerated as it is for fungi, and would there be the same multiplier effect?
The time from the first collection of a putative new species to its formal description varies greatly. Barleria deserticola (Figure 2a), from the Namib coastal desert was first collected 160 years ago, by the explorer Friedrich Welwitsch, but was only re-found in 2009 by US botanist Erin Tripp and named in 2019 (Darbyshire, Tripp, & Chase, 2019). In contrast, the description and publication of Inversodicraea koukoutamba (Podostemaceae) collected from a waterfall in Guinea in 2018 took only one year from the first collection (Cheek, Molmou, Jennings, Magassouba, & van der Burgt, 2019).
Delays in publication can reflect a lack of availability of specialist taxonomists with the capacity or time to write and publish a formal paper describing new species. They can also result from a former convention, in which naming a species from only a single specimen, showing a single phase of the species' life cycle, was considered poor science (Cheek & Bridson, 2019  The five plant families with most new species published in 2019 (IPNI, 2020).

Numbers of new species published in 2019
Orchidaceae 288 Rubiaceae 157 Compositae (Asteraceae) 100 Araceae 78 Leguminosae 71 The top five vascular plant families in terms of numbers of accepted species (WCVP, 2020).  attracts interest and encourages others to seek new material in the field, sometimes resulting in rediscovery of species hitherto considered extinct (Humphreys, Govaerts, Ficinski, Nic Lughadha, & Vorontsova, 2019).
In fungi, confusion about the identity of the already published species hinders progress. In many groups, the type specimens of all published species need to be studied first, or neo-or epitypes designated for old names, before new names can be published for species. In addition, many new species are discovered from environmental specimens (usually soil samples) but, according to the current rules of nomenclature for fungi they cannot be named because of a lack of a physical voucher specimen which needs to be deposited in a fungarium (Lücking & Hawksworth, 2018; See BOX 2 for more on naming conventions). The debate is also still ongoing as to whether a short DNA sequence is sufficiently robust evidence to justify the publication of a new species name (Zamora et al., 2018), especially as thousands of well-known names still lack DNA barcodes (Schoch et al., 2014). Currently, two Specialpurpose committees are exploring the use of DNA sequences as types, and this topic is due to be further discussed during the next International Mycological Congress in 2022 (May, 2018)

| WHERE HAVE THE NE W S PECIE S B EEN FO U N D?
The top three source countries for the discovery of new plant spe-

BOX 2 Naming new taxa
The starting point for scientific names for plants and fungi is Linnaeus's Species Plantarum (Linnaeus, 1753), which pioneered the binomial standard still used today. Names of taxa at that time were usually descriptive or geographic and in Latin, as in "grandifolia," meaning "big-leaved," or "taprobanus" meaning "from Taprobane." This approach is still popular e.g. Humicola quadrangulata (referring to the quadrangular ascospores of this fungus), Neosetophoma salicis (growing on Salix) and Turquoiseomyces eucalypti (referencing the characteristic green-blue discolouration of the host tissue surrounding conidiomata on Eucalyptus leaves). However, as numbers of species in genera increased, selecting appropriate descriptive epithets or names not already in use became more challenging. Thus it became common to commemorate specimen collectors (rarely credited otherwise) or famous people worthy of being honoured by  (Richards, 2019). The UK has not seen publication of a full, sexual, indigenous species for many years.
In complete contrast, new species of fungi are still found almost everywhere: from the tropics to alpine areas, from Europe to Antarctica ( Figure 3). On a continental scale, most species of fungi were described from Asia (41%) and Europe (23%) following the pattern of new species published in 2017 (Niskanen, 2018). This is largely due to the fact that the economies of countries in Asia have improved and thus can support such research, and the strong taxonomic tradition

| NE W PL ANTS PUB LIS HED IN 2 019
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| Food and drink
Six new species of Allium, the genus that gives us garlic, onions, shallots, leeks and chives were discovered in Turkey (

| Timber and crafts
Among the new species of timber tree were a Chlorocardium (greenheart) and Cedrela domatifolia (mahogany family) the latter (

| Herbs and Spices
Three new species of Zingiber, the genus that produces ginger   Figure 2b) and Muscari. The spectacular red-flowered Gladiolus mariae was found on a sandstone

| NE W FUNG I PUB LIS HED IN 2 019
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| New plant pathogenic fungi
Many new plant pathogenic fungi associated with plant diseases of economically important plants were discovered in 2019, predominantly from the phylum Ascomycota ( Figure 4).
Notably, one of the Fusarium oxysporum strains (formerly known as Tropical race 4) responsible for Panama disease of banana (Musa), that threatens the productivity of one of the most popular cultivars, Cavendish, was recognized as the new species Fusarium odoratissimum. In addition, eight further members of this complex were described as distinct novel species (Maryani et al., 2019).
Also, six new pathogens of grape (Vitis vinifera) were described The total number of accepted species is 1963 (as of March 2020) and is expected to exceed 2000 species by the end of 2020 (see above left). Several hundred further new Begonia species potentially remain to be found, with species new to science considered highly likely to be found in Borneo and New Guinea.
Ceratocystis destructans, a canker-causing pathogen of almond (Holland et al., 2019), and Dwiroopa punicae, which causes leaf spotting and fruit rot in pomegranate (Punica granatum) (Xavier, 2019). In this latter study, the new family Dwiroopaceae was also proposed to accommodate this genus.
Pathogens of important non-food plants were also discovered, such as Cytospora elaeagni associated with canker disease of

| New decomposers
Decomposer fungi recycle nutrients from nearly all types of organic material, which can then be used by other organisms. The spore- Each year some of the world's mycologically most neglected regions and habitats become hotspots of new species discoveries.
Studies yielding some of the more impressive numbers (40 + species each) of new decomposers in 2019 ranged from a major contribution to the checklist of wood-inhabiting poroid Basidiomycota (bracket fungi) in Africa (e.g., Ryvarden, 2019aRyvarden, , 2019bRyvarden, , 2019c, through projects focusing on microscopic Ascomycota from very specific microhabitats. One example of the latter was a study of decaying wild fruits and seed pods found mainly in Thailand that yielded eight new genera and 50 new species (Jayasiri, 2019

| New lichens
Lichen

| New animal-associated fungi
The diversity of fungi is largely unknown and undescribed, and this is no different for the animal-associated fungi. For example, as little as 1.5% of all insect-associated fungi has been described thus far (Mueller & Schmit, 2007). Animal-associated fungi have great potential for biological control of insect pests. Beauveria bassiana is the most widely used biocontrol agent against many major arthropod pests (Garcia-Estrada et al., 2016). Some species, like those of the genus Cordyceps, are used in traditional Chinese
Given that mycologists have only observed a fraction of the estimated diversity in the Kingdom Fungi, it is no surprise that the ecological diversity of groups of fungi is also underestimated. Indeed, newly described species often extend known ecological ranges. Of note in 2019 is Emericellopsis koreana, isolated from the gut of a mosquito larva in South Korea (Phookamsak et al., 2019). Until the discovery of this species, taxa in Emericellopsis had been found from estuarine or F I G U R E 5 A new animal-associated fungus published in 2019. Cordyceps jakajanicola (Hypocreales, Ascomycota), Thailand. (a) Fungus on cicada nymph (sexual morph); and (b) fungus on cicada nymph (asexual morph). The fungus grows inside its host and sprouts its reproductive parts outside the host´s body. Many of the species, together with their insect hosts, are used in traditional Chinese medicine. Photos: BIOTEC marine habitats associated with seaweed, agricultural substrata, peat, forest soil, and rhizomes (Gonçalves, Vicente, Esteves, & Alves, 2020).

| WHERE WILL THE NE X T NE W PL ANTS AND FUNG I B E FOUND?
Despite the ongoing loss of natural habitat in the 21st century, new plant species continue to be discovered. In some extreme cases, the numbers of known species in groups considered to be well-known have nearly doubled since 2000. One example is the tropical Asian pitcher plants, Nepenthes, long cultivated in plant collections, which when revised in 2001 were considered to have 87 species globally (Cheek & Jebb, 2001). However, fuelled by troops of citizen scientists searching remaining scraps of natural habitat intensively within the SE Asian range of the genus, hoping for and making new discoveries, the number of species has now risen to 181 and is still rising (Murphy et al., 2020). Another genus showing rapid growth, especially in SE Asia is Begonia (BOX 3).
Statistical estimation of the quantity and distribution of the plant species still awaiting discovery suggests that they are heavily concentrated in the regions of the world already recognized as biodiversity hotspots (Joppa, Roberts, Myers, et al., 2011 ). For example, it is highly likely that some new discoveries will continue to be made even in areas that are considered intensively surveyed such as the highly species-diverse Cape of South Africa. This is because, typically, many new species discovered today tend to be highly geographically localized (narrowly restricted endemics), with few sites and minute footprints: more widespread species already tend to have been discovered . Such restricted distributions tend to result in these new species being highly likely to be unwittingly threatened by habitat clearance, making their discovery, naming and extinction risk assessment urgent: species lacking IUCN threat status are less likely to be safeguarded than those that have IUCN status (Nic Lughadha et al., 2020). Today, species that are already globally extinct are still being described and published e.g.
New fungi will likely be found in the same under-sampled areas as plants, but our knowledge of fungi is so incomplete that new species will also continue to be discovered even in well-studied and densely populated areas such as the Netherlands ( New fungi can be found almost anywhere, from the rocks of Antarctica, to the dung of sheep, the nests of leaf-cutting ants, sand dunes and even in the air of basements (Crous, Schumacher, et al., 2019;Crous, Wingfield, et al., 2019;Hyde et al., 2019;Rodrigues, 2019). They occur in terrestrial habitats but also in water, such as Annabella australiensis and Kamalomyces mangrovei growing on decaying wood in mangroves (Fryar et al., 2019;Hyde et al., 2019).
Numerous new species of fungi, as well as undescribed higher taxonomic ranks, are also discovered each year from environmental samples (e.g., Tedersoo, Bahram, & Puusepp, 2017). Most of these, however, remain unnamed due to the lack of physical voucher specimens. One of the major challenges in fungal taxonomy is to shed light on these "dark taxa" (Lücking & Hawksworth, 2018;Ryberg & Nilsson, 2018).

| CON CLUS ION
Research and publication of the planet's remaining undiscovered plant and fungal species is essential if we are to halt biodiversity loss. If species remain unknown to science they cannot be factored into conservation planning and so the possibility to protect them from extinction is reduced. Furthermore, until species are scientifically documented they cannot be fully evaluated for their potential as new foods, medicines, and products for the benefit of humanity and of the planet. We recommend that more resources are invested in scientific discovery and description of plant and fungal species urgently, while they still survive. Priorities include more investment in training taxonomists, and creating employment and building and equipping collections-based research centers for them, especially in species-rich, income-poor countries where the bulk of species unknown to science are thought to await scientific discovery.

ACK N OWLED G EM ENTS
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