Psychotria sororiella M.-Arg., Mart. Fl. Bras. 6(5): 375. 1881.
Cephaelis sororiella (M.-Arg.) Standi., Field Mus. Publ. Bot. 7: 429. 1931.
Müller-Argoviensis treats these two taxa as distinct species, differing from one another, in addition to the vegetative characters, in relative length of calyx to ovary, type of calyx margin, and relative proportions of anthers. However, I can find no real floral differences between them, and consider them instead as variations of pubescent and glabrous parts of the same taxon. For example, on the isotype specimen of P. turbinella some buff pubescence may be observed in lines on the uppermost internode, and the youngest leaves show strongly ciliate margins (as in var sororiella). Moreover, the stipules are similarly conspicuously ciliate in both taxa. The prominently sulcate midrib and lateral nerves of the upper surface and the elevated nerves below show the same degree of development in both taxa, as is also evident in the bullate or rugulose tertiary venation of the upper leaf surface, the leaf shape, apex, and base.
The collection of Spruce 2076 was cited by Müller-Argoviensis as the second number under his Psychotria sororiella (Mart. Fl. Bras. 6(5): 375. 1881), but this actually is Psychotria podocephala (M.-Arg.) Standl., and is cited by Müller-Argoviensis as his first number under Mapouria podocephala (Mart. Fl. Bras. 6(5): 410), whereas Spruce 3682, cited by Müller-Argoviensis as his first collection number under Psychotria sororiella (Mart. Fl. Bras. 6(5): 375), is also cited by him under Mapouria podocephala as his second collection number. This duplication and citation of numbers under different taxa has led to considerable confusion, and was repeated by Standley in Rubiaceae of Venezuela (Field Mus. Publ. Bot. 7: 429, 456. 1931).
In Psychotria turbinella the head of flowers is surrounded by four petaloid bracts which are united in the form of a campanulate or subturbinate tube. This tube surrounds 8-10 outer bracts of the head, in which about 10 flowers are present, each flower surrounded by two bracteoles.