Virectaria stellata(Sabiceeae-Rubiaceae), a new sandstone cliff species from the Republic of Guinea with stellate hairs recorded for the first time in the Rubiaceae

Abstract

AbstractVirectariais a morphologically isolated genus of tropical African herbs or subshrubs, occurring from Senegal to Tanzania.Virectaria stellata, a new species from Guinea, is published. It is a perennial herb, with stems becoming creeping and rooting, to 60 cm long.Virectaria stellatahas stellate hairs, recorded here for the first time in the family Rubiaceae. We hypothesize that the stellate hairs of this species result from horizontal gene flow from an Acanthaceae, most likelyBarleria, due to their common and perhaps unique microstructure.Virectaria stellatais found in Forécariah and Kindia Prefectures in the Republic of Guinea. The species occurs in fissures in vertical sandstone rock at altitudes of 450 to 910 m, in sun or half-shade. An overview of sandstone endemic plant species in the vicinity of the newVirectariais provided. No threats have been observed, therefore,Virectaria stellatais provisionally assessed here as Least Concern (LC).