A new and unusual species of Dichaea (Orchidaceae: Zygopetalinae) from Costa Rica

A new and florally unusual species of the genus Dichaea is described and illustrated from Costa Rica, where it is apparently endemic, and its relationships are discussed. Dichaea auriculata is compared with the group of species close to D. graminoides, from which it can be distinguished by the lip with a long isthmus, provided with two rounded auricles at the base, instead of the sessile lip typical of the group. It is also compared with another Costa Rican endemic in the same complex, D. gracillima, from which it can be distinguished by the autogamous, mostly cleistogamous, flowers, the3-lobed lip with rounded basal lobes, the high keel along the lip isthmus, and the bifid ligule of the column. Notes on the habitat and the ecology of the new species are provided.