A massive Critically Endangered cloud forest tree, Microcos rumpi (Grewiaceae) new to science from the Rumpi Hills, SW Region, Cameroon.

We describe (Grewiaceae) a massive new species to science from the Rumpi Hills of SW Region Cameroon, a proposed Tropical Important Plant Area. Confined on current evidence to submontane forest, the species is threatened by expanding habitat clearance for farms and is assessed as Critically Endangered. A large tree, attaining 35 40 m height, and 80 cm trunk diam. at 1.3 m above ground, its biomass is calculated as in the range of 7 8 metric tonnes. It is the third tree species of the genus recorded from Cameroon and only the fourth recorded west of D.R. Congo. A key to these four species is presented. The concept of in Africa in relation to is discussed, and three new combinations are made, transferring three species names from to : (R.Wilczek) Cheek, (R.Wilczek) Cheek and (R.Wilczek) Cheek.