Plagiosiphon intermedium (Leguminosae, Detarioideae), a new tree species from the Ngovayang forest in Cameroon.

Plagiosiphon intermedium Burgt, Ngansop & Tchiengué, Leguminosae–Detarioideae, is described and illustrated. It is a tree, to 34 m high, with a stem to 66 cm diameter. The leaves have (2 –)3–4(– 5) pairs of opposite leaflets, with the low-est pair often sub-opposite. The flowers are unknown. The fruit is a pod, brown, the valves more or less obovate in outline, 7–9.5 × 3.5–4.5 cm, without visible veins out-side, short dense hairy outside. Plagiosiphon intermedium occurs in primary rain forest, at 760–870 m elevation. The tree species is endemic to the Ngovayang Massif in the South Region of Cameroon. Three herbarium collections have been made, in an extent of occurrence of only 0.51 km2. Plagiosiphon intermedium is provisionally assessed as Endangered B1(iii,v)+B2(iii,v).