A key to the Sabdariffa scotellii (Baker f.) Mwachala & R. L. Barrett group (Malvaceae, Hibisceae) in West Africa with descriptions of two new, threatened species from bowal habitats in the Republic of Guinea

Two species new to science from the Republic of Guinea, West Africa are placed in the informal Sabdariffa scotellii group within Sabdariffa (formerly Hibiscus sect. Furcaria, Malvaceae). The group is characterized by the combination of entire (not bifurcate) involucellar bracts, non-aculeate stems, 3–5 - lobed leaves abaxially with 1 or usually 3 nectar glands at the base of the midrib and flanking lateral nerves.

An identification key to the four species of the group is presented. The new species are described in this paper as Sabdariffa sangaredi Thiam & Cheek, sp. nov. (from bauxitic low altitude bowal in the Sangaredi area) and Sabdariffa kounounkan Cheek, sp. nov.

(from montane sandstone bowal on the Kounounkan table mountain). Their taxonomic affinities and ecology are discussed. Both species are assessed as Critically Endangered using the IUCN 2012 standard.

We also discuss other recently described endemics of sandstone habitats in Guinea.