Typification of Citharexylum (Verbenaceae) names based on the collections gathered by the Botanical Expedition to the Viceroyalty of Peru

Abstract

There has been considerable discussion on the history of the collections gathered by the Botanical Expedition to the Viceroyalty of Peru, members of which remained thirty-four years (1777–1811) collecting in the New World. Two species names in Rauvolfia (Apocynaceae), Rauvolfia flexuosa, the basionym of Citharexylum flexuosum since Don’s combination in 1831, and Rauvolfia macrophylla, now treated as a synonym of the former species name, were published by Ruiz and Pavon based on plant material they collected in Peru as well as material herborized by Tafalla, a subordinate who remained exploring in South America after the return of Ruiz and Pavon to Spain. A third species name, Citharexylum dentatum, was published by Don also based on Peruvian material collected by Tafalla. The resale and/or redistribution to other herbaria of a large part of the material gathered by the expedition members in South America has caused much confusion and hindered proper typification of these names. Based on thorough study of original material, original manuscripts, and pertinent literature, a critical review is provided and lectotypes are designated for the names R. flexuosa, R. macrophylla, and C. dentatum.