A New Species of Hydnora (Hydnoraceae) from Southern Africa

We describe a new species, Hydnora visseri (Hydnoraceae), a holoparasitic perennial species from the Karas Region of Namibia and the Northern Cape Province of South Africa. The new species is a distinct segregate of Hydnora africana and is restricted to transitional and winter rainfall areas of southern Namibia and northwestern South Africa. Hydnora visseri only occurs with H. africana in sympatry in a narrow geographical band where their respective host species occur together. Distinctly longer tepal lobes and the largest flower metrics in the section Euhydnora distinguish H. visseri from H. africana and Hydnora longicollis. At one known site where H. africana and H. visseri occur in sympatry, differences in flowering phenology and host preference appear to reinforce species boundaries.