Bracteoles are dark coloured and longer than in Tacca leontopetaloides. Leaves with a much shorter petiole and a smaller leaf diameter. My conclusion for now - an unnamed Tacca species, different from Tacca leontopetaloides. Mount Yokolo in Cabo Delgado Province.
Detail of the dark purple (almost black) flower parts of the unidentified Tacca species. This specimen was found on Mount Erati (Nampula province of Mozambique).
""Black Tacca" flowering in its natural habitat, rocky slopes on Mount Erati (Nampula province of Mozambique). Note the very short leaf petioles. Most of the 15-20 cm petiole is burried in the soil."