Keetia nodulosasp. nov. (Rubiaceae - Vanguerieae) of West - Central Africa: bacterial leaf nodulation discovered in a fourth genus and tribe of Rubiaceae

Abstract

SummaryKeetia nodulosaCheek, a cloud forest climber nearly endemic to Cameroon, with a single record from Nigeria, is described and illustrated. It is remarkable as the first known species to be recorded with bacterial leaf nodules (BLN) in the genusKeetia,and also, in the tribe Vanguerieae. Other genera in Rubiaceae with BLN arePsychotria(Psychotrieae),Sericanthe(Coffeaeae) andPavetta(Pavetteae). The BLN inKeetia(Vanguerieae) are illustrated for the first time here.The characteristics and significance of bacterial leaf nodulation inKeetia nodulosaare discussed in the context of rapidly growing knowledge on the subject in flowering plants.Keetia nodulosais provisionally assessed using the 2012 IUCN standard as Endangered (EN B2ab(iii). The importance of its conservation, and options for achieving this are discussed in the context of recent extinctions of other plant species in Cameroon.This discovery of a new cloud forest species is discussed in relation to other cloud forest plant species described in the last twenty years which are also distributed over the highlands of the western half of Cameroon.