Monographs Details: Roentgenia sordida (Bureau & K.Schum.) Sprague & Sandwith
Authority: Maguire, Bassett. 1978. The botany of the Guayana Highland--part X. Mem. New York Bot. Gard. 29: 1-288.
Discussion:1. Roentgenia sordida (Bureau & K. Schumann) Sprague & Sandwith, Kew Bull. 1932: 91. 1932.
Arrabidaea sordida Bur. & K. Schum., Mart. Fl. Bras. 8(2): 30. 1896. Type. Br. Guiana, upper Rupununi River, Schomburgk 1296 (B*, not seen).
The two collections cited here (Pinkus 1, 2000 ft, and Tillett & Tillett 45685, 470 m), both from the Upper Mazaruni River Basin of Guyana, are the first upland records. The former was distributed as Cydista aequinoctialis and subsequendy overlooked.