Type. Tree 30-40 feet tall, Cerro Isibukuri, Rio Kananari, Comisaria del Vaupes, Colombia, 4 Aug 1951, Richard E. Schultes dc I. Cabrera 13384. (Type said to be at Gray Herb.). Known only from the type locality.
The plant so designated by Schultes was related by him to M. ptaritepuiana Steyermark of the Gran Sabana region of Venezuela, but differs in having "... abruptly acuminate (instead of apically rounded) leaves which are larger, by having three (instead of five) anthers in each staminal bundle, by its much shorter pedicels and by its lemon-yellow and basally pink (instead of greenish white and apically pink) petals."
No specimens of M. rupicola have been available to me. The diagnosis and admirable plate indicate spirally contorted stamens (in the description 3, in the plate 4). Thus, on morphological grounds, for these specimens there may be indicated a stronger relation with M. pulchra and/or M. coccinea. But Schultes is correct in associating M. rupicola with M. ptaritepuiana, insofar as to their occupancy of Roraima sandstone areas.