Two new species of Kefersteinia (Orchidaceae : Zygopetalinae)

Two new species of the genus Kefersteinia, K. saccata and K. medinae, are described and illustrated from Costa Rica and Ecuador, respectively. K. saccata has apparently no close relatives; among the species with truly cylindric-umbonate callus, it is compared with K. retanae and K. wercklei, from which it differs in the porrect petals, the saccate, ovate-subrhombic lip, shorter than the column, and the obreniform basal callus. K. medinae belongs to a group of species of mainly Central American distribution, ranging southward to Ecuador. It differs from its closest relative, K. costaricensis, by the,lateral almost horizontal sepals, the immaculate sepals and petals, and the distinctly obovate, truncate lip, provided with a triangular apicule.