Psathura has long been recognized as similar to Psychotria, and most authors have acknowledged that Psathura should be included within Psychotria but continued to recognize it. It was been separated based on its 3-5-locular ovaries and fruits and 3-5 stigmas, vs. 2-locular with 2 stigmas in Psychotria. The genus Psathura was recognized by Bremekamp (1963) and Verdcourt (1989) for eight species found in Madagascar, the Mascarenes (3 species), and the Seychelles (1 species). When the multilocular ovary is disregarded, Psathura as circumscribed by them appears to comprise at least two distinct groups of species, one in Madagascar and one in the Mascarenes, and the species from the Seychelles does not appear to be closely similar to either of these. However all of these species have been more recently included within Psychotria based on molecular data (Razafimandimbison et al., 2014), and the multilocular ovary found in these analyses thus appears to be secondarily derived within a clade of species with bilocular ovaries.
The species that have been included in Psathura from Madagascar are fairly similar and probably closely related to each other. They all share generally similar stipules and leaf general aspect, a lax, cymose, pedunculate, rather corymbiform inflorescence arrangement with the basalmost pair of secondary axes well developed and often as long at the primary axis, and small fruit size. None of species that have been included in Psathura from Madagascar is well documented, with the flowers in particular pooly known probably because the flowering plants are not easy to separate from Psychotria due to the multilocular ovary not being very evident.
There has been some confusion about the name and distribution of one species from Madagascar that has been treated in Psathura: Bremekamp described it as a new species from Madagascar but mistakenly used for it the specific epithet "polyantha", which was previously published for a different species, Psathura polyantha Cordem., that is found only in Reunion. Verdcourt later published the replacement name Psathura batopedina for the species from Madagascar.