was based on the Guyanan collection Ri. Schomburgk 406 seen in the Berlin herbarium. P. schomburgkii was described as a glabrous herb, having long petiolate, suborbicular leaves with emarginulate apex, glabrous on both sides; the ovary ending in a short style with apical stigma. No further collections have been reported since. More collections are needed to circumscribe and differentiate the taxon. It may be a distinct taxon, but it may also be an atypical specimen belonging to P. quadrifolia.