Since the preliminary review of this genus in 1957 (Mem. N. Y. Bot. Gard. 9:337-343. 1957), I have described two additional new species and now still two more new ones require such treatment. Keys are presented below- to a.ssociate the new taxa with their nearest relatives and to distinguish from each other the members of assemblages that include new species.
In the paper referred to above, the genus was divided into several sections; in a recent paper Fasbender (Lloydia 22:139. 1959) mentions these sections as having been "invalidated by subseciuent findings (Cowan, 1958)." It is necessary to correct the author's misinterpretation of the additional information presented in the latter reference. In the first place, the original treatment was specifically descrited as "preliminary;" it was a tentative arrangement of subgeneric taxa and nothing more. It is therefore not at all surprising that there is no support in the pollen morphology for m y alignment. The fact is that some of the characteristics used in the preliminary key have since been found to be less precise than was originally thought, but this does not invalidate the subgeneric structure erected initially; the basic groups are, for the most part, just as recognizable now as then. Certainly, I do not intend to make any major modifications in m y earlier treatment until the genus is much better known; new species are being added to it with every expedition to the Guayana region and a re-evaluation is not justified at this time. The genus is not so confused and complex as Fasbender states; rather it is a genus so poorly known in its component parts that it m a y tend to confuse the non-taxonomist.