Deinbollia onanae (Sapindaceae), a new, Endangered, montane tree species from the Cameroon Highlands.

Deinbollia onanae (Sapindaceae-Litchi clade) is here formally named and characterised as a new species to science, previously known as Deinbollia sp. 2. Cameroon has the highest species-diversity and species endemism known in this African-Western Indian Ocean genus of 42 species. Deinbollia onanae is an infrequent tree species known from five locations in surviving islands of montane (or upper submontane) forest along the line of the Cameroon Highlands. It is here assessed as Endangered according to the IUCN 2012 standard, threatened mainly by clearance of forest for agriculture. The majority of tree species characteristic of montane forest (above 2000 m alt.) in the Cameroon Highlands are also widespread in East African mountains (i.e. are Afromontane). Deinbollia onanae is one of only a very small number of species that are endemic (globally restricted to) the mountain range. It is postulated that this new species is in a sister relationship with Deinbollia oreophila, which is a frequent species of a lower (submontane) altitudinal band of the same range. It is further postulated that seed dispersal is or was by frugivorous birds, potentially turacos, alternatively by primates such as Preuss s monkey.