Current Knowledge and Research Perspectives on Bryophytes in West Africa

Abstract

Bryophytes are non-vascular plants comprising mosses, liverworts and hornworts. In West Africa, they are one of the least investigated components of biodiversity, receiving far less attention than vascular plants. This systematic review synthesizes the current knowledge on bryophytes in West Africa and identifies gaps and future prospects for advancing bryophytes research. Since the earliest explorations in the 18th century, bryophyte research in West Africa has remained poorly developed, with a noticeable bias toward certain countries over other countries. Over the past four decades, bryophyte research and the number of recorded species have increased. To date, 1175 bryophyte species and infraspecific taxa, representing 320 genera and 120 families, were recorded in the region, of which 6.47% are endemic. This documented diversity surely does not represent the full flora of the region: many species are evidently still undescribed. Another major constraint on advancing knowledge is the scarcity of specialists in the region and the lack of sustained scientific interest and academic focus in the taxonomic group. A priority for advancing knowledge on bryophytes in West Africa is to strengthen taxonomic research to document biodiversity, alongside comprehensive studies on bryophyte diversity and distribution across regions.

1. Introduction

West Africa comprises Benin, Burkina Faso, Cape Verde, Côte d’Ivoire, The Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Mauritania, Niger, Nigeria, Senegal, Sierra Leone, and Togo [1], along with the island nations of São Tomé and Príncipe and Bioko. Biogeographically, the region is structured around five major phytochoria: the Guinea-Congolian, Guinea-Congolia/Sudanian, Sudanian, Sahel, and Sahara [2]. The region supports a wide range of vegetation spanning from evergreen and semi-deciduous forests in the south (the Guinean Forests biogeographic zone), through a transitional Guinean forest–savannah mosaic to Guinea and Sudanian savannas in the north [2]. Vegetation patterns are strongly shaped by the Dahomey Gap, a dry corridor that divides the rainforests into two distinct blocks, producing fragmented forest patches and relics, with savanna–forest mosaics within the Guineo-Congolian zone [3].

The West African coast is recognized as a biodiversity hotspot [4], but this biodiversity is under increasing threat from deforestation, agricultural expansion, urbanization, fire regimes, and climate change [5]. These pressures accelerate habitat fragmentation and species loss, particularly among cryptogamic groups such as bryophytes, which remain poorly studied in the region [6]. Bryophytes are especially vulnerable because they depend on microclimatic stability and are often confined and specialized niches, placing them at a high risk of extinction before adequate documentation [7]. West Africa has also been described as a biodiversity “dark spot”, with few species described and geolocated [8]. This deficit is even worse for bryophytes, which are highly threatened by habitat fragmentation, especially of rainforests that otherwise serve as global biodiversity hotspots [9].

Although bryophytes in West Africa have long been overlooked, research has gradually increased over the past few decades. The earliest collections of bryophytes were made by Palisot de Beauvois and Afzelius between 1786–1790 in Nigeria and Sierra Leone [10].

The first comprehensive and pioneering study was Dusén’s two-volume moss flora for the West coast of Africa [11], followed by Schultze-Motel’s catalogues of mosses for West Africa [12], and Richards and De La Varde’s moss flora of Nigeria and Cameroon [13,14]. Subsequent contributions were largely limited to national checklists, such as Egunyomi and Olarinmoye’s for Nigeria [15]. More significant works began towards the end of the 20th century. By 1990, more comprehensive studies occurred. For instance, Frahm et al. reported 171 species, including 131 mosses and 39 liverworts in Cape Verde, highlighting unexpected richness [16]. In Benin, studies from 1998 and 2000 added 41 species to the national record [17,18]. Since 2000, new records and floristic surveys have been published from São Tomé and Príncipe, Ghana, Liberia, Côte d’Ivoire, Senegal, Togo, Sierra Leone, Nigeria, Benin, and Cape Verde [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35]. Even so, the current knowledge on bryophytes in West Africa remains incomplete and scattered, with early works primarily focused on taxonomy and species cataloguing [12].

This paper aims to synthesize the current knowledge on bryophytes in West Africa and identify research gaps and challenges, and propose future directions to advance bryological research in West Africa.

2. Results

2.1. Historical and Contemporary Bryological Exploration in West Africa: A Synthesis of Literature

During the mid-15th century, travelers, traders, and chroniclers documented aspects of climate, topography, flora and fauna, and human settlements in West Africa [36]. One of the first recorded visitors was Alvise Cadamosto, a Venetian explorer in the service of Portugal, who travelled to the Senegambia region in 1455–1456 [36]. He documented local crops, staple foods, agricultural practices, and plant specimens [37,38]. From the 15th century to late 17th century, botanical collections were predominantly directed toward vascular plants [39]. This could explain the lack of data on bryophytes during these periods.

The most noticeable botanical collections in the Senegambia region began in 1748 with the visits by renowned French Naturalists [36]. The earliest recorded collector was the French Naturalist Michel Adanson (1727–1806) [40,41], who spent five years in Senegal and the neighboring areas from 1748. During this time, he extensively explored and gathered over 5000 specimens of plants, many of which are deposited at the Muséum Nationale d’Histoire Naturelle (P) [40]. In the 19th century, many other French Naturalists followed in Adanson’s footsteps to study West African flora [36]. Notable among them was the botanist Palisot de Beauvois, who was the second explorer of Oware and Benin (actual Nigeria). In the 1790s, the botanist George Samuel Perrottet (1790–1870), a French naval pharmacist and naturalist, François Mathias René Leprieur (1799–1870), and Jean-Pierre Heudelot, who explored the area of Senegambia, respectively, in 1824 to 1829, 1824 to 1829, and 1836 to 1837 [36,41].

The first bryophytes explorations and collections were made by the French Naturalist Palisot de Beauvois (1805–1820), who collected a few mosses and hepatics in 1786 to 1788 in the southern part of actual Nigeria [10]. In 1792 and 1794, the Swedish Afzelius visited Sierra Leone and collected some mosses [10]. In the same period, the Scottish explorer Mungo Park collected mosses when he explored the River Niger [10]. These collections were left without description and unidentified [10]. They were later sent to the British botanist William Mitten (1819–1906), who identified and described many of them, and are currently housed at the herbarium at New York Botanic Gardens [42].

A little before the 1860s, Charles Barter (1821–1859) and Theodor Vogel (1812–1841), the German botanists from the Kew Royal Botanic Gardens, under the expeditions of British botanists for vascular plants to the Gulf of Guinea, made some collections of mosses around the river of Niger and the neighboring countries [10,41]. In April 1859, Gustav Mann (1836–1916) was sent by the Kew Royal Botanic Gardens to replace Charles Barter as a botanist in the same area [43]. His expedition allowed him to gather much larger collections of mosses in 1861, among which most were collected in the high elevation areas like Bioko and São Tomé and Principé, revealing the vast diversity of bryophytes in the sub-region [10]. Also, the Austrian Friedrich Welwitsch (1806–1872), under his expeditions supported by the Portuguese government to Angola, explored the Western region of Africa and made considerable collections in São Tomé and Príncipe and in other countries [11,19]. It was around 1890 that most of these species collected by these expeditions were described by William Mitten (1819–1906), Karl Johann August Müller (of Halle, 1818–1899), and were published later by Viktor Ferdinand Brotherus (1849–1929), Jean Édouard Gabriel Paris (1827–1911), and others [10]. In addition, the Swedish Per Karl Hjalmar Dusén (1855–1926) collected in 1890 to 1892 around 100 species of mosses in Nigeria and Liberia, from which most were described by himself, and others by Müller and a few by Brotherus [10,11]. As a result, dedicated bryological taxonomic treatments were largely absent from the literature between the initial period of species documentation and the first two decades of the 20th century (Figure 1).

After World War II (1939–1945), field conditions were positively transformed for botanists in the sub-region, like road building and air transport [10]. This facilitated accessibility and the improvement of health conditions in the region [10]. Consequently, many European and American botanists visited West Africa and made a lot of collections of bryophytes. It was the era of the beginning of massive collections in the sub-region (see Figure 1A). In 1947, under the British expedition, When Eustace Jones (1905–1992) first set foot in Nigeria with a great ambition: resolve the gap in bryophytes taxonomy in West Africa [44]. He was the most important collector and descriptor of many liverwort and hornwort species from West Africa [44]. His works highlight much of the liverwort and hornwort flora of the sub-region through his manuscripts on species description, revision, and, most importantly, his key for the identification of liverworts and hornworts from West Africa published by Wigginton in 2004, including those from some areas of Cameroon, Rio Muni, Bioko, and Annobon. His materials were in part deposited at the Kew Royal Botanic Gardens and other specimens at the Ibadan Forestry Herbarium (Nigeria). At the same time, Emilio Guinea López (1907–1985), a Spanish botanist, set foot on the island of Bioko and made a large collection of bryophytes. His samples were deposited at the Museo de Ciencias Naturales de Álava (Spain) and the New York Botanical Garden (United States) [45,46]. In 1935 and 1947–8 and in 1955, under the Cambridge Botanical Expedition, the botanist Paul Westmacott Richards (1908–1995) collected many hundreds of specimens in Nigeria, Ghana, and Sierra Leone [10,13]. His materials were identified and others described by himself and then deposited in the Botanical Department of the British Museum, and at the Kew Herbarium for collections made in 1955 [13]. In 1969 and 1973, E. Assel, under his mission in Congo Brazzaville and in the Central African Republic, made many collections in Côte d’Ivoire, from which liverworts were stored at the Herbarium of the Higher School of Eszterházy, Eger (EGR), in Hungary, and mosses at the Laboratoire de cryptogamie du Muséum d’histoire naturelle de Paris (PC) [25]. After these expeditions, some catalogs and keys for identification and species revision were proposed for the bryoflora of West Africa (e.g., Katalog der Laubmoose von West-Afrika in 1975 by [12], A revision of West Tropical African Calymperaceae I. Introduction and Calymperes [47]).

During the exploration of the British botanists, some young West African researchers were interested in the field of bryology. For instance, the young Nigerian researchers Adeyemi Egunyomi and S. O. Olarinmoye collected, identified, and described mosses from Nigeria. In 1974, S. O. Olarinmoye studied the Ecology of epiphyllous liverworts from Nigeria [48]. In the same period, the two Nigerian botanists proposed a series of publications on mosses from Nigeria [15,49,50]. In 1982, they described for the first time Syrrhopodon obuduensis Egunyomi & Olar. (Calymperaceae) from Nigeria [51]. Another prominent botanist active during this period was Laurent Aké-Assi (1930–2014) from Côte d’Ivoire. He conducted extensive botanical collections within the country, some of which formed the basis for the description of new liverwort species in collaboration with Tamas Pócs in 1983 [25]. At this time to the beginning of the 2000s, explorations intensified across the sub-region, driven by the efforts from numerous botanists. Notable contributors included Martin James Wigginton (1944–2019), Jan-Peter Frahm (1945–2014), Tamas Pócs, Brian J. O’Shea, Claudia Dilg, among others, whose fieldwork and collections significantly advanced bryological knowledge in West Africa [16,17,18,52].

In the last two decades (2000–2010 and 2010–2020), bryophyte research has continued to expand markedly, with increased field surveys, taxonomic revisions, and regional collaborations contributing to a growing body of knowledge and herbarium resources in West Africa (Figure 1). During these periods, the number of local botanists interested in the field of bryology increased. For instance, in Nigeria (Olubukunola Oluwole Oyesiku, Izuchukwu Ezukanma, Abolade Oluremi Bolaji, and others), in Ghana (Adu-Gyamfi Anthony), in Togo (Abalo-Loko Goudjo Ameto), and in Sénégal (Diop Djibril), local botanists studying bryophytes were added to the list [26,28,30,31,32,53,54,55]. In 2017, Jiménez and Cano described Didymodon caboverdeanus J.A. Jiménez & M.J. Cano (Pottiaceae) for the first time from Cape Verde [56]. At the same time, the number of other non-local botanists adds to the sub-region exploring the bryoflora diversity. This could be exemplified by the significant increase in the number of publications related to taxonomy and species diversity in these periods (Figure 1). It could also be highlighting the increase in the number of species (Figure 1B). The increasing interest of African bryologists and some local West African bryologists may explain this result. This interest of local West African scientists in bryology could be the result of their commitment to the field of taxonomy.

Currently, bryophyte explorations continue growing in West Africa, and the number of young scientists in bryophyte research is increasing (Figure 1). In addition, many other local scientists are working in bryophytes taxonomy, identifying and describing species like Nigeria, Sao Tomé and Principe, Cape Verde, Senegal, Ghana, Benin, and Togo. For example, in 2023 and 2024, Martins and his collaborators [57] and Alia and his co-authors [33] described, respectively, Exormotheca martins-loussaoae Sim-Sim, A. Martins, J. Patiño & C.A. Garcia (Corsiniaceae) and Fissidens bassilae Alia, Brugg.-Nann. & Reeb (Fissidentaceae), a new species from Cape Verde and Benin. In 2021, Diop Djibril and his collaborators published the list of bryophytes from Senegal [27]. In 2022, Garcia and his collaborators [19] established the checklist of bryophytes from São Tomé and Principe. In 2021 to 2024, Garcia, Sim-Sim and their collaborators [34,35], Hodgetts and his co-authors [22], and Costa and his collaborators [58] updated, respectively, the bryophyte floras of Cape Verde, Ghana, and São Tomé and Principe. This may indicate the significant advances made in taxonomy and species identification, or an increasing awareness of the dearth of knowledge on bryophytes and the need to change the status quo (Figure 1A). Given the limited knowledge on the topic in the area, bryophyte research has recently attracted increased funding. We don’t want to say that there is also a lot of funding available now. For instance, the National Herbarium of Benin received funds from the JRS Biodiversity Foundation for the BryoBen project, implemented over the period 2023–2026. This initiative aims to mobilize data for the identification, taxonomy, socioeconomic importance, and conservation of bryophytes in Benin. These results may also be due to the growing institutional capacity in the sub-region, marked by the expansion of universities and research centers, and the emergence of locally trained bryologists in some WA countries, contributing to the improvement in bryophyte research [10].

Overall, few studies have addressed bryophyte taxonomy in West Africa [36.29%, (n = 45)], with most limited to species-level reviews compared to those that addressed species diversity. This low number of publications can be partially attributed to the scarcity of trained bryologists in the sub-region. As noted by Oyesiku [53], this shortage could be due to the fact that studies on the taxonomy of bryophytes in Africa remained problematic for African bryologists who faced many difficulties in species identification and species nomenclature for tropical bryophytes. Moreover, during 1950–1960, 1960–1970, and 1990–2000, no research was conducted in the fields of taxonomy of bryophytes in West Africa (Figure 1A). This prolonged lack of scientific attention has significantly contributed to the current delay in bryological research in the sub-region, especially when compared to the progress made in the study of vascular plants. For instance, while nearly all countries in the sub-region have developed comprehensive floras for vascular plants, similar initiatives are virtually absent for bryophytes [59]. To date, published research related to bryophyte phylogeny has not been recorded in West Africa.

Indeed, plant taxonomy, particularly for bryophytes, requires microscopic observations and specific equipment, which can be difficult to obtain without adequate funding, whereas at the same time, the disinterest of young scientists regarding the field of botany is increasing at a global level [60]. This declining interest in botany has led to a decreasing number of botanists, especially taxonomists [60]. This shortage is becoming increasingly evident across Africa, and the situation is even more critical when it comes to bryologists in the West African sub-region. Although a few researchers in Nigeria have explored this area, the findings of the present study suggest that very little has been done to describe and name bryophyte species in West Africa. This could also be due to the lack of appropriate infrastructure, such as high-quality microscopes. Furthermore, since species description requires microscopic examination, bryophytes demand even more detailed analyses of spores and other structures, sometimes necessitating the use of electron microscopes. For example, in Nigeria, Bolaji and Faluyi went beyond morphological and anatomical descriptions by including cytological (chromosomal) studies [31]. Although their approach represents a noteworthy contribution to bryophyte taxonomy by integrating cytogenetic data into species identification, the study is constrained by limitations in imaging quality. Chromosome-counting techniques require high-resolution visualization of chromosomal structures across mitotic stages, which depends on access to advanced microscopy. Despite these constraints, such cytological investigations complement morphological analyses and contribute to a more integrative framework for species delimitation. It is also worth noting that other chromosome-based studies have been conducted, reinforcing the relevance of cytogenetics in bryophyte systematics [31].

2.2. Research Bias

Bryophytes are the second largest group of land plants after the vascular plants, comprising around 25,000 species worldwide [61,62]. Scientific publications in bryology vary across countries in West Africa. The majority of bryological research was from Nigeria, probably due to major British explorations such as those of When Eustace Jones (1905–1992), Paul Westmacott Richards (1908–1995), and others. In addition, this could be since, after the works of British explorers in the countries, many local botanists continued documenting bryophytes [53]. One of the important pieces of information is that Nigeria is among the first African countries in which scientific research was in considerable advancement in many research fields [63], which may be linked to the population size, a high number of universities and research centres, and higher collaborations with Western countries [64]. Despite its smaller size, São Tomé and Príncipe received more attention, following Nigeria. Historically, the islands of São Tomé and Príncipe have gained many scientific visits, expeditions, and missions since the first explorations of the botanist George Don in 1822 [20]. From them, a lot of collections were made and stored at the Herbarium of Coimbra (COI), among which many were identified and/or were described [20]. These explorations considerably increased the bryological research in the islands, in addition to the recent works of Garcia, Sérgio, Shevock, and their collaborators [19,20,65], who mostly identified and listed the bryophyte flora of São Tomé and Príncipe. Cape Verde and Bioko have also been documented in bryophytes research. As Sao Tomé and Principe, Cape Verde, and Bioko were kept in the attention of many botanists visiting and exploring the bryoflora. For Cape Verde, C. Bolle in 1851 was the first collector of bryophytes, which were studied by C. Müller [16]. Later, the French botanist Auguste Chevalier in 1934, Knut Byström from the Naturhistoriska Riksmuseum in Stockholm in 1958, Dr. Per Sunding from the University of Oslo in 1972, H. Muhle in 1980, and recently in 1995, Anja Lindlar visited the Archipelago [16]. From these expeditions, a lot of bryophyte specimens were collected, and many samples were identified and described. These works lead to the massive research found in this country. Concerning the Island of Bioko, one of the first explorations of bryophytes was made by Gustav Mann (1836–1916) in the 1860s. In 1937, the French botanist Henri Jacques-Félix (1907–2008) visited the Island and made a lot of specimens, among which most were identified, described, and published by Potier de la Varde, and were deposited at the Muséum national d’histoire naturelle de Paris (P) [66]. Later in 1947, the Spanish botanist Emilio Guinea López (1907–1985) gathered numerous samples, which were published in 1997 by Infante and his collaborators [45]. Frank Müller, in 1996 and 2002, made expeditions to the Island and collected many bryophyte specimens, which he published in 2006 [67]. Ghana also received more attention in bryophytes research. Like Nigeria, Ghana also benefited from British exploration. Among them, Richards and others around the mid-1970s collected many specimens, enriching the research on bryophytes in the country. It is also worth mentioning the works of Hodgetts and Adu-Gyamfi, who provide good studies on the bryoflora of Ghana [22,23,55]. In the Republic of Benin, although the first bryophytes exploration dates back to the 18th century, the country witnessed its first large-scale bryophytes exploration in 1998 and 2000, led by European botanists [17,18]. It is only in the recent five years, in the 2020s, that Alia Boris, a national PhD student who contributed to sample collections and specimen identification [68,69]. However, from 2023 to 2024, more than 3000 bryophyte samples were collected across the country and stored at the Herbier National du Bénin throughout the BryoBen project, from which identifications of specimens have started. This is expected to expand the current bryoflora of the country. Senegal was one of the first countries to receive the first botanical explorations in West Africa [37]. It was also the first main country to be awarded the high and qualified university of the sub-region (Université de Cheikh Anta Diop de Dakar). However, studies on the floristic diversity of bryophytes are still at an embryonic stage, despite that collections are stored in the two herbaria in the field of species conservation, Dakar and IFAN herbaria [27]. The key issues are the lack of specimen identification and the lack of qualified local taxonomists trained. Côte d’Ivoire has also been explored by Frahm, Porembski, Gyarmati, and others, and some specimens were identified [25,52]. However, since then, little is known about bryophytes from the country. In addition, the lack of local researchers specializing in the field of bryology could justify these gaps. In Sierra Leone, few bryophyte samples were collected by Richards in the mid-1970s. However, little research has been performed in the country since then. In the Republic of Togo, as in many other countries, the bryoflora of Togo was explored in the 1970s. Thanks to the work of Schultze-Motel, who provided the preliminary information on the moss flora of Togo in 1979 [70]. Later, between 1983 and 1985, J.-F. Brunel made a lot of collections in the country, which were published by Tixier in 1989. However, the only recent and local researcher in the field of bryology was, in his memory, Abalo-Loko Goudjo Ameto, who provided the checklist of liverworts and hornworts of Togo [28]. This regrettable scientist would be one of the local pioneer bryologists in the Dahomey Gap. Unfortunately, in the least known countries, the bryophyte explorations were still very marginal, although there were some explorers who visited these countries since the beginning of the 19th century, such as Mungo Park in his visit to the River of Niger, and Mali, and David Linder on his visit to Liberia. These countries include those located in the Sahelian zone of West Africa, namely Burkina Faso, Mali, and Niger, alongside Liberia, which lies outside the Sahel but shares similar ecological and socio-political challenges. The difficulties for visitors and explorers to travel to these countries (probably due to terrorism) could justify this shortage in bryophytes research. It could also be due to the political instabilities since the departure of European colonizers from now and the insistence on wars in these countries. Nonetheless, the common issue in bryophyte research in all countries of the sub-region is the lack of specialists [71]. This delay in bryological research could align with Hallingbäck and Tan, who stated that, to date, bryological research is generally grossly under-funded [6].

2.3. Spatial Distribution of Bryophyte Studies in West Africa over the Last Four Decades

Over the last four decades, research in bryology has gained increasing attention from scientists across the world [72,73]. It was the period dedicated to the considerable increase in bryophytes studies in West Africa, marked by the first comprehensive surveys and taxonomic revisions.

In total, 103 publications related to taxonomy and species diversity were recorded for the sub-region over the last four decades. Nigeria showed the highest number of publications, indicating that Nigeria was the most significant contributor to bryophytes research in West Africa (Figure 2). It accounts for 21.35% (n = 22) of the total papers recorded related to the aspects of species diversity and taxonomy over the last four decades. Our results show that Nigeria’s contributions were mainly in species diversity (checklists) with 14.56% (n = 15) (Figure 2).

The islands of São Tomé and Príncipe followed with 14.56% (n = 15) of the publications recorded in the sub-region. It contributed mostly to species diversity with 9. 70% (n = 10) and taxonomy with 4.48% (n = 5) (Figure 2). The Cape Verde islands ranked next, contributing with 9.70% (n = 10) of the total publications, including 6.79% related to species diversity and 2.91% to taxonomy. The island of Bioko followed with 6.79% (n = 7) of the total publications recorded. In addition, Benin, Ghana, Guinea-Bissau, Côte d’Ivoire, Senegal, Sierra Leone, and Togo followed the above-mentioned countries, as those that contributed to the research in bryology in West Africa (Figure 2). In contrast, although there was a significant increase in bryophyte research in West Africa in the last four decades, in Burkina Faso, Guinea, Gambia, Liberia, Mali, and Niger, the publications recorded in bryology remained lower (Figure 2).

Furthermore, twenty-one publications with a regional focus on West Africa or Sub-Saharan Africa were identified. This distribution highlights the imbalances in the research capacity due to the lack of experts throughout the sub-region. National-level differences in bryological research output may be influenced by factors such as gross domestic product (GDP), research and education quality, official language, and political stability, all of which can shape a country’s scientific productivity and conservation priorities [73].

2.4. Bryophyte Flora of West Africa

2.4.1. Floristic Composition

The advancements in bryophyte systematics have allowed more accurate assessments of global, continental, and regional floras, including those of tropical Africa. In this work, we extensively utilized the checklists of O’Shea [74] and Wigginton [75], as well as all recent literature mentioning WA floristic diversity, to provide a synthesis on bryophyte diversity in the sub-region. Initially, to ensure taxonomic consistency across countries, we first compiled raw species lists for each nation considered in this study, based on all published records. These lists were then cross-verified and updated using the bryonames.org “https://www.bryonames.org (accessed on 5 July 2024)” database, which reflects current nomenclatural standards and synonyms for bryophytes. The updated lists were merged to establish a unique list for the sub-region after every duplicate was removed. Taxonomic nomenclature and species delimitations followed the framework established by Goffinet [76] for mosses and the updated classification provided by Söderström [77] for liverworts and hornworts. West Africa, although historically underexplored, harbors a remarkably bryophyte diversity shaped by varied ecological zones and biogeographic influences [78]. In total, 1175 bryophyte taxa and infraspecific taxa are recorded from West Africa. All three big bryophyte clades were represented: Bryophyta (mosses), Marchantiophyta (liverworts), and Anthocerotophyta (hornworts) (Figure 3). The WA flora is composed of 755 species of moss distributed in 226 genera and 79 families; 400 species of liverworts, distributed in 88 genera, 38 families, and 20 species of hornwort distributed in 6 genera and 3 families.

The bryophyte species richness varies across the three major groups [73]. In the moss group, Bioko, Nigeria, and Côte d’Ivoire were the richest countries, with 218, 2018, and 204 species, respectively (see Appendix A:

Table A1. Distribution of bryophyte species within the West African countries.

Country	Hornworts	Mosses	Liverworts	Endemicity	Species
Benin	2	43	39	2.63%	84
Bioko	6	218	179	7.89%	403
Burkina Faso	0	13	0	0	13
Cape Verde	1	188	62	13.16%	251
Gambia	0	2	1	0	3
Ghana	4	143	172	7.89%	319
Guinea	0	199	64	25%	263
Guinea-Bissau	0	2	6	0	8
Côte d’Ivoire	1	203	111	9.21%	315
Liberia	0	70	16	1.32%	86
Mali	0	17	2	5.26%	19
Niger	0	11	8	1.32%	17
Nigeria	2	218	157	7.89%	377
São Tomé and Príncipe	7	137	203	19.74%	347
Senegal	0	80	36	2.63%	116
Sierra Leone	6	110	143	5.58%	259
Togo	1	89	57	3.95%	147

). These countries were followed by Guinea (200 species), Cape Verde (187 species), Ghana (144 species), São Tomé and Príncipe (137), and Sierra Leone (111 species). In contrast, the remaining countries (Benin, Burkina Faso, Gambia, Guinea-Bissau, Liberia, Mali, Niger, Senegal, and Togo) of the sub-region presented little richness to the moss species diversity reported (see Appendix A: Table A1).

In the liverwort group, São Tomé and Príncipe had the highest diversity, with 203 species (see Appendix A: Table A1). It was followed by Bioko, Ghana, Nigeria, Sierra Leone, and Côte d’Ivoire with 179, 172, 157, 143, and 111 species, respectively. In contrast, Guinea (64), Cape Verde (62), Togo (57), Benin (39), Senegal (36), Liberia (16), Niger (8), Guinea-Bissau (6), Mali (2), and Gambia (1) presented low diversity of species in this group (see Appendix A: Table A1). However, no liverwort species were recorded from Burkina Faso.

In the hornwort group, few species were recorded in the WA countries. The highest species richness was from São Tomé and Príncipe, with 7 species, followed by Bioko and Sierra Leone with 6 species (see Appendix A: Table A1). In contrast, few species were found in Ghana (4), Benin (2), Nigeria (2), Cape Verde, Côte d’Ivoire, and Togo (1 species each). However, in Burkina Faso, Gambia, Guinea, Guinea-Bissau, Liberia, Mali, Niger, and Senegal, no hornwort species have been reported yet (see Appendix A: Table A1).

The WA bryoflora represents 4.17% of the overall bryophyte worldwide, and 27.01% of that for Sub-Saharan Africa [74,75]. This low number of recorded species may be attributed to the limited taxonomy research efforts on bryophytes in the sub-region. Several countries in the region still lack local expertise in bryology, especially in taxonomy, highlighting a gap in national scientific capacity. In addition, bryophytes are largely unknown to the general public, particularly among local communities, due to their inconspicuous nature, which likely explains the lack of attention given to them in national conservation and environmental management policies. From a regional level, the bryophyte species richness reported here is slightly higher than the 882 species recorded by Ros and his co-authors [79] in North Africa. Nevertheless, several studies have been carried out more recently, including those by El-Saadawi and his collaborators, Youssef, Taha, Osman and his collaborators [80,81,82,83,84,85]. It is worth noting that the checklist for North African bryophytes was already completed by 1999. Figure 4 illustrates some terricolous and epiphytic bryophyte species found in Benin. The illustrations of these species were based on their large distribution, ecological representativeness, frequent occurrence in surveyed habitats, and distinct morphological traits that aid field identification.

2.4.2. Endemism of Bryophytes in West Africa

In West Africa, bryophytes faced several threats, exposing them to a high risk of extinction, while strategies for their conservation were not yet documented [86]. This aligns with Hallingbäck and Hodgetts, in their book “Mosses, Liverworts, and Hornworts: Status Survey and Conservation Action Plan for Bryophytes”, who emphasized that many bryophyte species are threatened with extinction [87]. The most serious threats were similar to those of vascular plants, which were related to habitat loss due to anthropogenic pressures [88]. Indeed, studies reporting threats and the conservation of bryophyte species are rare in the sub-region [86]. In this work, we recorded 76 bryophyte species endemics to West Africa, from 15 countries, including Benin, Bioko, Cape Verde, Ghana, Guinea, Côte d’Ivoire, Liberia, Mali, Niger, Nigeria, São Tomé and Príncipe, Senegal, Sierra Leone, and Togo. These species were distributed into 48 genera, 29 families, and 4 classes. The most endemic species belong to the moss group with 61 species, followed by the group of liverworts with 13 species (Figure 3). In contrast, a lower number of endemic species was observed in the hornwort, with 2 species (Figure 3). In addition, the most endemic were observed in the family of Sematophyllaceae. It was followed by the families of Lejeuneaceae, Hypnaceae, Fissidentaceae, Dicranaceae, Pottiaceae, and Pylaisiadelphaceae. The most endemic species were found in Guinea, with 19 species. It is followed by São Tomé and Príncipe (15 species), and Cape Verde with 10 species, Bioko with 6 species, Ghana and Nigeria with 6 species, and Sierra Leone with 5 species. In contrast, Mali, Togo, Benin, Senegal, Liberia, and Niger presented few endemic species. This number of endemic species represents 0.03% of the overall bryophyte worldwide, 1.97% of that for Sub-Saharan Africa [74,75], and 6.47% of the total number of species occurring in West Africa. The number of endemic species could be due to the fact that many countries in Africa were not biologically well explored [6]. This could suggest that, if bryological research increases in the under-explored countries, many species considered endemic to WA could change their status, so that the endemic species could decrease or increase.

2.4.3. Identification Keys for Bryophytes of West Africa

Few species identification keys have been published for West Africa. The single well-established species identification key documented to date is the one for liverworts and hornworts by Jones, E. W., published by Wigginton [44]. This key is old and needs to be revised. However, some identification keys have occasionally been proposed for new records, revisions, and species diversity papers (e.g., [26,47,89]). Additionally, many species from WA were reported in papers focusing on species identification keys at the global level in revision papers, as well as those outside the West African region (e.g., [90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105]). Unfortunately, most of these keys are often incomplete and do not consider all species found across the entire sub-region, unlike Jones E. W.’s key for liverworts and hornworts, which covers the whole West African sub-region. This limitation may be attributed to the same reasons mentioned in the previous sections. The development of an identification key first requires expertise in the already established taxonomy.

3. Discussion

3.1. A Review of Literature and Bryological Exploration

We highlighted that there is a clear taxonomic bias in the historical gap between vascular plant and bryophyte exploration in West Africa. While vascular plants were documented from the 15th century [36], bryophytes only began to be collected in the late 18th century [10]. This delay could likely be caused by the historically lower scientific priority given to non-vascular plants [106,107]. The non-description of Palisot de Beauvois, Afzelius, and Mungo Park’s early collections for decades limited their impact on taxonomic literature. It was not until the mid- to late 19th century that systematic examination began, notably through the work of Mitten, Müller, and Brotherus [10]. This chronology explains the absence of dedicated bryological literature before 1895 [11], despite earlier specimen gathering. It also highlights the dependence on European institutions and experts for taxonomic validation, which contributed to delays in regional bryophyte documentation. The late emergence of bryology in West Africa is not merely chronological but structural, mostly with logistical constraints. Understanding this helps contextualize current gaps and highlight the urgent need for the involvement of local young scientists in bryological research in the sub-region.

From the post-World War II period to the present, bryological research in West Africa has undergone a marked expansion (Figure 1). This growth was improved field conditions and infrastructure, which facilitated access for foreign botanists and enabled large-scale specimen collection. Our synthesis reveals that 122 publications were recorded, with 63.11% focused on species diversity. The increase in publications during 2010–2020 correlates with a notable increase in species records (Figure 1B), reflecting both intensified fieldwork and improved taxonomic capacity. This shift is partly attributable to the emergence of local bryologists and regional research networks, which began to fill the longstanding gap in taxonomic expertise. The historical imbalance in bryophyte taxonomy, dominated by foreign experts and delayed local engagement, can be linked to systemic undervaluation of taxonomy within biological sciences. This aligns with [71], who indicated that the poor image for taxonomy among biological sciences, its concomitant devaluation of taxonomic publications, and the shortage of professional positions and research grants have played a devastating role in the development and recruitment for the discipline. The recent rise in local contributions, such as species descriptions from Nigeria, Benin, and Cape Verde, signals a turning point. Thus, the increase in species diversity literature is not merely a product of intensified exploration but also the beginning interest of the local scientists in bryology. It is so important to continue investment in local capacity, such as the BryoBen project in Benin, which is essential to address the historical gap in bryophyte knowledge across the sub-region.

We also showed that in WA, over the last four decades, bryophyte research has expanded, yet remains unevenly distributed across countries. Nigeria leads in the number of publications, reflecting both its ecological diversity and the presence of active young bryological scientists and dynamic research institutions. This could certainly be justified by the favorability of the vast range of climates that benefit the country (Figure 2). Our analysis suggests that research productivity is also shaped by structural factors such as institutional capacity, funding availability, and scientific networks. Island nations like São Tomé and Príncipe, Cape Verde, and Bioko also show high publication rates, likely due to their altitudinal gradients and insular biodiversity [108,109], which attract international collaborations. Their inclusion in broader biogeographic comparisons with regions like La Réunion and Madagascar may further stimulate interest in bryological research. In contrast, countries such as Burkina Faso, Mali, Niger, and Liberia exhibit an embryonic stage, with minimal bryological research. The arid climates such as the Sudanian, Sahelian, and Saharan (see Figure 2) could highly support the less interest of scientists to explore these climate zones, as bryophytes ecologically prefer the humid zones. Training bryologists and support for research in bryology would help reverse this trend [6]. Historical underinvestment in taxonomy and limited access to international funding have led to these gaps. Our findings showed that twenty-one publications focused on the regional level. This result could point out the need for coordinated, transnational research frameworks. Strengthening local expertise through training programs and institutional support could help bridge these disparities and foster inclusive bryological development across the sub-region.

3.2. Bryophyte Flora of West Africa

A total of 1175 bryophyte species were recorded for WA, representing 4.70% of global bryophyte diversity and 30.41% of that for Sub-Saharan Africa [74,75]. For instance, in East Africa, Marline and her co-authors [110] recorded 1144 species for Madagascar. Recently, Wilding and his co-authors [111] reported 822 species for the La Réunion islands. In addition, in 1999, Ros and his co-authors [79] reported 882 bryophyte species for the checklist of North Africa. This richness highlights the lack of floristic exploration and ecological studies across WA countries. This result suggests the urgent need to intensify bryophyte research in WA forests. This aligns with Marline and her co-authors [107] when they concluded that bryophytes need urgent research and conservation investments.

The distribution of bryophyte richness across West African countries is highly heterogeneous. Bioko, Nigeria, São Tomé and Príncipe, Ghana, and Côte d’Ivoire account for the majority of species, while several countries, including Burkina Faso, Mali, and Niger, remain underexplored. These disparities are not solely due to climatic constraints; they could also be due to limited national expertise, insufficient funding, and the absence of coordinated floristic surveys. This strongly supports Marline and her collaborators when they emphasized that despite being locally abundant, especially in the moist evergreen regions, and potentially unique in the dry and arid regions, no attention has been given to bryophytes with regard to their importance for setting conservation priorities, particularly with reference to landscape management recommendations and policy [107].

This review showed 6.47% of endemic species occurring in West Africa. This endemism rate is strongly lower than that recently found by Phephu, estimated at 24.44% of liverwort and hornwort endemism rate for Southern Africa [111]. In addition, island ecosystems such as Madagascar and New Caledonia report endemism rates exceeding 30% [110,112,113]. This low endemism rate (6.47%) further illustrates the region’s underrepresentation in global bryophyte research. This contrast may be partly ecological, but it could also reflect historical biases in bryological research. The inconspicuous nature of bryophytes and their marginal role in public awareness and policy frameworks contribute to their neglect in conservation planning. In addition, despite their ecological importance, bryophytes are rarely integrated into national biodiversity management strategies.

4. Future Direction

Despite their taxonomic and ecological diversity and their worldwide distribution, bryophytes remain poorly studied, especially in Africa and particularly in West Africa [61,87]. While all regions globally have had at least some research conducted in this field, not all West African countries have been explored in terms of bryology. Our results show that in five West African countries (Burkina Faso, Gambia, Guinea-Bissau, Mali, and Niger), very little bryological research has been conducted concerning taxonomy, phylogeny, species diversity, or identification keys. It is therefore crucial to initiate studies on bryophytes in these countries to improve the overall understanding of bryophyte flora across the continent. In addition, since most local populations in West African countries appear to have limited awareness of bryophytes, there is an urgent need for research into their socio-economic importance. Furthermore, additional studies are needed to support conservation efforts and promote the sustainable management of bryophyte resources.

Firstly, we provided evidence of a lack of knowledge regarding the floristic composition of bryophytes in five West African countries. It is therefore crucial to carry out systematic inventories across all West African countries to gain a comprehensive understanding of bryophyte diversity across different regions and habitat types, and to determine which species are locally common, rare, or threatened within the sub-region.

Secondly, we demonstrated that, among the existing studies, few have focused on bryophyte taxonomy and the development of identification keys in West Africa. Addressing these aspects is essential to advance the current knowledge and facilitate the accurate identification of bryophyte species.

Thirdly, we observed that only a limited number of species have been taxonomically revised out of the 1175 species recorded in West Africa. It is thus important to carry out thorough revisions of all reported taxa to improve their species descriptions and clarify their taxonomic positions.

Fourthly, we highlighted the lack of phylogenetic research on bryophytes in the West African sub-region. This finding further supports the evidence that bryophytes are not only generally neglected in Africa but are even more overlooked in West Africa. Currently, the classification of bryophytes is based on the morphology and development of the peristome [114]. However, phylogenetic studies are essential for correcting, renaming, and reclassifying species using molecular analyses [115]. There is an urgent need to conduct comprehensive genetic analyses of all recorded taxa to improve and refine their taxonomic classification.

Fifthly, the limited funding allocated to bryophyte research may partly explain the scarcity of studies on this plant group in West Africa. This funding gap is likely due to the low level of awareness among funding bodies regarding the ecological and scientific importance of bryophytes, underlining the need for targeted awareness-raising efforts.

More importantly, very few individuals are currently interested in botany, and even fewer in bryology, resulting in a critical shortage of specialists in Africa, particularly in West Africa. It is therefore essential to integrate bryology into academic curricula to train and engage young scientists, fostering the development of future specialists in the field. Given the alarming rate at which natural habitats are being lost globally, such initiatives are extremely urgent and must be implemented without delay.

5. Conclusions

Bryophyte research is strongly neglected in West Africa. Despite the first exploration on them dating back to the 18th century, little literature exists on bryophytes for the sub-region compared to that for vascular plants. In addition, very little species diversity was recorded, supporting a critical lack of data on floristic exploration and ecological research on bryophytes in the sub-region. To address these gaps, the involvement of researchers, organizations, governments, and universities could raise scientific and public awareness of the importance of bryophytes.