D. glabrifolia Ducke, Jour. Wash. Acad. 25: 196. 1935.
Sandwith21 pointed out the true identity of D. macrostachya Benth. and its restriction to the slopes of Roraima and other tabular mountains in Guayana.
D. congestiflora was then proposed to include distinct but superficially similar material from the Mazaruni region of British Guiana. Ducke22 proposed D. glabrifolia to accommodate a lower Amazon variant which differed only in reduction of pubescence, especially on the undersurface of the leaflets. Examination of available material, including subsequent collections from the Mazaruni region (Tillett & Tillett 45548, 45648, 45843) and Pakaraima Mountains (Maguire, Maguire, & Wilson-Browne 46133a, 46144) and Para (Ducke 282; Archer 7547; Black, Froes, & LeDoux 50-9789; Pires 51806) together with the cited new record for Amapa, has led to the observation that the degree of pubescence varies greatly in both regions, but tends to be somewhat more pronounced in the Mazaruni material. However, a number of specimens from that area are less pubescent than Ducke 282; Black, Froes, & LeDoux 50-9789; and Inuin, Pires, & Westra 48363. Although the breadth of Suriname and French Guiana presently exists as a disjunction, there are no morphological bases for maintaining two species.