Keita (Aptandraceae-Olacaceae s.l.), a new genus for African species previously ascribed to Anacolosa, including K. deniseae sp. nov., an Endangered submontane forest liana from Simandou, Republic of Guinea

Abstract

SummaryWe show that the two continental African species previously ascribed to the genus Anacolosa, differ in so many architectural, floral and vegetative characters from the remaining species of the genus (which occur from Madagascar to the western Pacific, including the type) that they clearly represent a separate genus. The African genus represented by these two species is unique within the Olacaceae s.l. (excluding Erythropalaceae) in being a climber (vs shrubs or trees in Anacolosa sensu stricto). Climbing in the two African species is achieved by perennial hook-like structures formed by a combination of five separate traits each of which is unknown elsewhere in the Olacaceae s.l. We formally delimit, describe and name this new African genus as Keita. Placement is tentatively in Aptandraceae but confirmation by molecular studies is required. We describe a new species from Guinea as Keita deniseae sp. nov. and transfer the Central African (Democratic Republic of Congo (DRC), Republic of Congo & Gabon) species from Anacolosa to the new genus as Keita uncifera comb. nov. Keita deniseae is assessed using the IUCN (2012) criteria as Endangered due to the threat of clearance or degradation of forest habitat for mining and agriculture, while K. uncifera is assessed as Least Concern in view of its large range, number of locations and low levels of threat. We review the discovery of Keita deniseae in the light of other recent discoveries of new taxa in both Simandou and the Republic of Guinea.