Orchidaceae acostanae: typification of Costa Rican orchid species described by Rudolf Schlechter from collections by Guillermo Acosta

ABSTRACT Rudolf Schlechter (1872–1925) described several orchid taxa based on specimens collected in Costa Rica during the first half of the 20th century. Unfortunately, the type material kept at the Botanical Museum of Berlin-Dahlem (B) was destroyed in the bombing of Berlin, Germany, in 1943. To complete the typification of names proposed by Schlechter, based on orchid collections attributed to Guillermo Acosta in Costa Rica, we have compiled a list of 22 names. Previously, 11 lectotypifications and five neotypifications were proposed on this material. However, we found six names that lacked typification. Therefore, formal typifications are proposed for Acostaea pleurothalloides, Dichaea similis, Goodyera micrantha, Lepanthes acostae, L. pubilabia, and Stelis acostae. Additionally, we provide a biographical context to understand Acosta’s relationship with Schlechter and the historical background of these collections. Finally, we provide bibliographical references and illustrations for lectotypes and neotypes. This work is part of a series focused on the nomenclature and typification of orchid names proposed by Schlechter in Costa Rica, aimed at clarifying our understanding of his species concepts in the Neotropics. Further, the typification of the names based on the collections made by the brothers Alfred and Curt Brade is necessary to complete this series.