Cephaelis oblonga DC. Prodr. 4: 535. 1830.
Uragoga oblonga (DC.) O. Kuntze, Rev. Gen. 2: 961. 1891.
Although de Candolle indicated that the type locality was “Guiana Gallica,” a photo of the presumed type from the Delessert Herbarium of G is labelled “Cayenne.” A specimen from P collected by Melinon in 1845 and labelled Cephaelis oblonga agrees with the other specimens examined from French Guiana and adjacent Rio Oiapoque of Territorio Amapa, Brazil. No specimens, actually, have been seen from British Guiana. Photos have been distributed by F from B under the unpublished name of “Cephaelis jaramea Sagot” from French Guiana, collected by Sagot 931. This collection is identical with Cephaelis oblonga. The photo of the type of Cephaelis oblonga shows the rigid, broadly lanceolate, outer involucral bracts and small, few-flowered heads characteristic of Cephaelis oblonga.
Psychotria oblonga is characterized by the minute puberulence of the upper stems, puberulent stipular sheaths, small narrow heads of only 2-3 flowers enveloped by narrow dorsally minutely puberulent bracts, minutely puberulent petioles, and minutely pilosulous-spreading hairs along each side of the lower midrib. An additional character is the thickened, upwardly dilated, several angled or acutely ridged peduncle passing directly into the thickened involucral bracts, clearly shown on the photo of the type of Cephaelis oblonga.