Abstract
We test the hypothesis that the tree species previously known as Deinbollia sp. 2. is a new species for science. We formally characterise and name this species as Deinbollia onanae (Sapindaceae-Litchi clade) and we discuss it in the context of the assemblage of montane tree species in the Cameroon Highlands of West-Central Africa. The new species is a shade-bearing, non-pioneer understorey forest tree species reaching 15 m high and a trunk diameter that can attain over 40 cm at 1.3 m above the ground. Seed dispersal has been recorded by chimpanzees (Pan troglodytes ellioti) and by putty-nose monkeys (Cercopithecus nictitans) and the species is used by chimpanzees for nesting. Cameroon has the highest species-diversity and species endemism known in this African-Western Indian Ocean genus of 42, mainly lowland species. Deinbollia onanae is an infrequent tree species known from six locations in surviving islands of montane (sometimes also upper submontane) forest along the line of the Cameroon Highlands, including one at Ngel Nyaki in Mambilla, Nigeria. Deinbollia onanae is here assessed as Endangered according to the IUCN 2012 standard, threatened by severe fragmentation of its mountain forest habitat due to extensive and ongoing clearance for agriculture. The majority of the 28 tree species of montane forest (above 2000 m alt.) in the Cameroon Highlands are also widespread in East African mountains (i.e. are Afromontane wide). Deinbollia onanae is one of only seven species known to be endemic (globally restricted to) these highlands. It is postulated that this new species is morphologically closest to Deinbollia oreophila, a frequent species at a lower (submontane) altitudinal band of the same range. Detailed ecological data on Deinbollia onanae from the Nigerian location, Ngel Nyaki, where it has been known under the name Deinbollia “pinnata”, is reviewed.
Highlights
As part of the project to designate Important Plant Areas (IPAs) in Cameroon, we are striving to name, assess the conservation status and include in IPAs (Darbyshire et al, 2017) rare and threatened plant species in the threatened natural habitat of the Cross-Sanaga interval (Cheek et al, 2001).Several of these species were previously designated as new to science but not formally published in a series of checklists ranging over much of the Cross-Sanaga interval
In this paper we test the hypothesis that the high-altitude tree species formerly designated as ‘‘Deinbollia sp. 2’’ (Harvey et al, 2004; Cheek et al, 2004; Cheek, Harvey & Onana, 2010), ‘‘Deinbollia sp.’’ (Chapman & Chapman, 2001) or ‘‘Deinbollia pinnata’’ (Abiem et al, 2020), is a new species to science, and we describe, characterise, and name it as Deinbollia onanae Cheek
Deinbollia pinnata Schum. & Thonn. is a common lowland West African species that occurs from Guinea to Nigeria, it differs in being densely hairy, so that the lower surface of the leaflets are softly hairy to the touch due to dense, patent, translucent hairs, and it is usually a small shrub of disturbed habitats, with an unbranched, raceme-like inflorescence that is pendulous in fruit, with hairy fruits 12–13 mm wide
Summary
As part of the project to designate Important Plant Areas (IPAs) in Cameroon ( known as Tropical Important Plant Areas or TIPAs, https://www.kew.org/science/ourscience/projects/tropical-important-plant-areas-cameroon), we are striving to name, assess the conservation status and include in IPAs (Darbyshire et al, 2017) rare and threatened plant species in the threatened natural habitat of the Cross-Sanaga interval (Cheek et al, 2001). Several of these species were previously designated as new to science but not formally published in a series of checklists (see below) ranging over much of the Cross-Sanaga interval. The fruits develop 1–3 indehiscent, apocarpous fleshy mericarps (Fouilloy & Hallé, 1973)
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