New taxonomic and conservation status of Ossiculum (Vandeae, Orchidaceae), a highly threatened and narrow-endemic angraecoid orchid from Central Africa.

In the context of producing a revised phylogenetic Linnean taxonomy of angraecoid orchids, the monotypic
and narrow-endemic genus Ossiculum is synonymised with Calyptrochilum. Accordingly, a new combination
in Calyptrochilum is proposed for Ossiculum aurantiacum. The morphological and DNA-based
evidence for this transfer is discussed. Moreover, Calyptrochilum aurantiacum is here firstly reported outside
Cameroon, with a record from the Republic of the Congo. The Red List conservation status of this
species is reassessed and it is to be downgraded from “Critically Endangered” (CR) to “Endangered” (EN),
following the recent discovery of additional subpopulations in Cameroon.