A peer-reviewed open-access journal PhytoKeys 147: 1–191 (2020) Checklist of coastal forests of Kenya 1 doi: 10.3897/phytokeys.147.49602 CHECKLIST http://phytokeys.pensoft.net Launched to accelerate biodiversity research An annotated checklist of the coastal forests of Kenya, East Africa Veronicah Mutele Ngumbau1,2,3,4, Quentin Luke4, Mwadime Nyange4, Vincent Okelo Wanga1,2,3, Benjamin Muema Watuma1,2,3, Yuvenalis Morara Mbuni1,2,3,4, Jacinta Ndunge Munyao1,2,3, Millicent Akinyi Oulo1,2,3, Elijah Mbandi Mkala1,2,3, Solomon Kipkoech1,2,3, Malombe Itambo4, Guang-Wan Hu1,2, Qing-Feng Wang1,2 1 CAS Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Gar- den, Chinese Academy of Sciences, Wuhan 430074, Hubei, China 2 Sino-Africa Joint Research Center (SA- JOREC), Chinese Academy of Sciences, Wuhan 430074, Hubei, China 3 University of Chinese Academy of Sciences, Beijing 100049, China 4 East African Herbarium, National Museums of Kenya, P. O. Box 45166 00100, Nairobi, Kenya Corresponding author: Guang-Wan Hu ([email protected]) Academic editor: P. Herendeen | Received 23 December 2019 | Accepted 17 March 2020 | Published 12 May 2020 Citation: Ngumbau VM, Luke Q, Nyange M, Wanga VO, Watuma BM, Mbuni YuM, Munyao JN, Oulo MA, Mkala EM, Kipkoech S, Itambo M, Hu G-W, Wang Q-F (2020) An annotated checklist of the coastal forests of Kenya, East Africa. PhytoKeys 147: 1–191. https://doi.org/10.3897/phytokeys.147.49602 Abstract The inadequacy of information impedes society’s competence to find out the cause or degree of a prob- lem or even to avoid further losses in an ecosystem. It becomes even harder to identify all the biologi- cal resources at risk because there is no exhaustive inventory of either fauna or flora of a particular re- gion. Coastal forests of Kenya are located in the southeast part of Kenya and are distributed mainly in four counties: Kwale, Kilifi, Lamu, and Tana River County. They are a stretch of fragmented forests ca. 30−120 km away from the Indian Ocean, and they have existed for millions of years. Diversity of both fauna and flora is very high in these relicts and the coastal forests of Eastern Africa, extending along the coast from Somalia through Kenya and Tanzania to Mozambique, are ranked among the priority bio- diversity hotspot in the world. In spite of the high plant species richness and their importance towards supporting the livelihoods of the communities that live around them, floristic studies in these forests have remained poorly investigated. Hence, based on numerous field investigations, plant lists from published monograph/literature, and data from BRAHMS (Botanical Records and Herbarium Management Sys- tem) database at East African herbarium (EA), we present a detailed checklist of vascular plants recorded in this region. Our results show that Kenyan coastal forests play an essential role in the flora of Kenya and Copyright Veronicah M. Ngumbau et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. 2 Veronicah M. Ngumbau et al. / PhytoKeys 147: 1–191 (2020) the plant diversity of the coastal forests of East Africa. The checklist represents 176 families, 981 genera, 2489 species, 100 infraspecific taxa, 90 endemic plants species, 72 exotic species, and 120 species that are included in the current IUCN Red List of Threatened Species as species of major concern. We also discov- ered three new species to the world from these relicts. Thus, Kenyan coastal forests present a remarkable and significant center of plant diversity. Keywords Biodiversity, checklist, coastal forests, endemic, threatened species Table of contents Introduction ............................................................................................................. 2 Material and methods............................................................................................... 4 Study area .......................................................................................................... 4 Plant collection and nomenclature ..................................................................... 4 Results and conclusion ............................................................................................. 6 Species diversity ................................................................................................. 6 Growth forms .................................................................................................... 6 Species in need of conservation attention ........................................................... 7 Endemic species of Kenyan coastal forests .......................................................... 8 New Records .................................................................................................... 11 Exotic species ................................................................................................... 11 Conclusion....................................................................................................... 13 Checklist ................................................................................................................ 15 Part 1 Lycophytes ............................................................................................. 16 Part 2 Monilophytes ......................................................................................... 16 Part 3 Gymnosperm ......................................................................................... 20 Part 4 Angiosperms .......................................................................................... 21 Acknowledgments ................................................................................................ 188 References ............................................................................................................ 189 Introduction Africa is among the world’s major centers of endemism and species-rich biodiversity re- gions (Burgess and Clarke 2000; Linder 2001). It hosts several centers of diversity with the eastern moist forests, which include coastal forests of East Africa and Eastern Arc forests as one of the significant centers of diversity (Lovett 1998). Another important center is the Congo Basin rainforest, which forms the second largest extent of continu- ous rainforest in the world (Linder 2014). Hamilton (1974, 1982) presented four cent- ers of endemism in Africa, which include Kivu, the East African coast, Cameroon Ga- Checklist of coastal forests of Kenya 3 bon area, and possibly small refugia in West Africa. Brenan (1978), working with data arranged according to country, identified the same regions as being rich in endemism. Coastal forests of Eastern Africa are ranked among the 35 identified world’s bio- diversity hotspots due to the concentration of many endemic species and habitat loss (Mittermeier et al. 1998, 2004; Olson and Dinerstein 1998). Together with the East- ern Arc mountains, they contain approximately 2000 endemic plant species (WWF– US 2003b ). These forests have lived for millions of years, of which they existed as a continuous belt of forest between the East and West coast referred to as the ancient Pan-African forest. However, fluctuation of climate, during the last 2 million years, caused their fragmentation, leading to loss of some lowland dry forests in Africa (Haw- thorne et al. 1981). Today, these forests have lost considerable amounts of their wilder- ness due to anthropogenic pressures leading to small fragments up to less than 5 km2, with the most extensive patches recorded in the Kenya coastal forests (Wass 1995; Habel et al. 2017). Loss of habitat due to human activities is the most severe threat to biodiversity and has become a major global environmental problem (Collinge 1996), hence, plant diversity protection has attracted more attention. Coastal forests of East Africa are ranked among the world’s ten most threatened forest hotspots because they have lost more than 90% of their original habitat. Similarly, Brooks et al. (2002) and Azeria et al. (2007) pointed out that Northern Kenya and Southern Tanzania coastal forests should be highly prioritized because they are in danger of losing most of their biodi- versity in coming times. Floristic studies, however, provide a basic outline for plant conservation. Based on these studies, it is possible to determine the condition of an ecosystem, the primary re- lationships of species with each other or with the environment, and the identity of rare species or widespread species (Ivanauskas et al. 2007). Therefore, they must be carried out not only in a particular area but also over time (Mota et al. 2017). In spite the coast- al forests of Kenya acting as significant reservoirs of carbon and biodiversity, and sup- porting the livelihoods of rural people, plant species diversity remains poorly studied. Despite a substantial amount of floristic research having been performed over the last decades on some of the Kenyan coastal relicts, (Robertson and Luke 1993; Lehmann and Kioko 2005; Luke 2005), a comprehensive study of the whole coastal region of Kenya is still extremely urgent due to its vast area and large number of threatened and endemic taxa. In addition, these forests are vital in providing ecological services at local, national, and global levels; it is therefore, crucial to understand their composi- tion. Here