A new record and emended description of a rare Amazonian white-sand species: Schoepfia clarkii (Schoepfiaceae)

Schoepfia clarkii is a rare species of Schoepfiaceae that to date has been known only from the single flowering specimen used in the original description from white-sand vegetation in Venezuela. Here we report new records for this species collected from the lower Negro River basin in Brazil, ca. 900 km from the type locality, but also from white-sand vegetation. We provide a more detailed description of the species, including the first observations of fruit characters, as well as illustrations, photographs, a distribution map, and discussion of its conservation status. We also provide a key for the identification of the South American species of Schoepfia.