The Diversity And Spatial Pattern Of Rubiaceae In Kenya, East Africa

Rubiaceae is the fourth largest family of angiosperms in the world,accounting for about 4% of all flowering plants in the world.It is widely distributed in tropical and subtropical regions,with a few herbs extending to the cold zones.Sub Saharan Africa,including tropical East Africa,especially the mountainous and coastal forests of Kenya and Tanzania,has a large number of Rubiaceae plants,especially rare and endemic species.In recent years,some new taxa of Rubiaceae in Kenya have been discovered and some new records have been reported,which shows that the diversity record of Rubiaceae in this area is not enough.The purpose of this study is to find out the diversity of Rubiaceae plants in Kenya and record their detailed distribution in 47 counties of Kenya through specimen inspection and field investigation.At the same time,according to the latest molecular system,this family of plants was revised to provide the background data for compiling the Flora of Kenya.In this study,more than 20,000 specimens of Rubiaceae from three herbaria were checked,the East African herbarium(EA),and the herbarium of Royal Botanical Garden(Kew)(K)and herbarium of Wuhan Botanical Garden,CAS(HIB)and all species were revised based on latest molecular system,thus an annotated checklist of the Rubiaceae family in Kenya was obtained.The taxonomic status of species was verified using online databases such as the World Checklist of Selected Plant Families,International Plant Names Index and The Plant List,as well as own revision after careful identification of the specimens.Based on the detailed longitude and latitude information of all specimens recorded,the county distribution of each species was calculated as well as the species richness and the endemic richness of each county in ArcGIS 10.2.The result show that in total there are 274 species of Rubiaceae in Kenya belonging to 81 genera,32 tribes and 3 subfamilies.According to the species richness analysis of 47 counties,the genera with the highest species richness are Psychotria L.,Pavetta L.and Oldenlandia L.The counties with the highest species richness are Kwale,Kilifi and Taita Taveta counties.There is a total of 36 endemic species of Rubiaceae in Kenya including 13 unknown species that need checking in the field.This study found that many regions of Kenya,especially the northern and northeastern counties still have very few specimen collections.The highest species richness was found in coastal counties.Based on the current IUCN assessment of the endangered species,there are two species of Rubiaceae in Kenya which are endangered and five species are vulnerable.More efforts should be made to protect the habitats of these species.Based on a large number of specimens' data and in combination with the latest molecular system,this study comprehensively studied the diversity of Rubiaceae in Kenya,including subfamilies,tribes,genera,and the endemism,as well as the countylevel distribution of Rubiaceae in Kenya.This research provided a basic information for the compilation of Flora of Kenya-Rubiaceae volume and field investigation and protection of Rubiaceae in Kenya.