This species is characterized by its somewhat slender habit; its rather small, oblanceolate, generally acute leaves with small but regularly developed domatia; its sitpules that are shortly united around the stem and have two well developed lobes on each side; its rather short to well developed peduncles with short, several-flowered, cymose inflorescences; its somewhat well developed calyx limb; its short yellow corollas; and its rather well developed, red, often ovoid fruits. As circumscribed here Psychotria reducta is a species similar to Psychotria parkeri, and these have often been confused and may not be distinct or a number of specimens may be incorrectly identified. These species are separated mainly by their stipules, which are partially fused into a basal tube that often splits along only one side and has the interpetiolar portion entire to 2-denticulate in Psychotria parkeri, vs. the stipules shortly fused with the basal portion not splitting or splitting on two sides and each interpetiolar portion with two well developed, slender, deciduous lobes. The stipule lobes are distinctive when present, but are usually found only on the stem apex. The leaves of Psychotria reducta are generally rather small, but they overlap in size with those of small plants of Psychotria parkeri. Bremekamp recognized two varieties, the glabrous var. reducta and var. pilosula with pilosulous pubescence on the veins of the lower leaf surface and the mouths of the domatia. No other distinctions are correlated with the pubescence details, which vary among the specimens referrable to this species, and these varieties are not recognized here. The specimens included in this species by Bremekamp were all from the subhumid central plateau, but as discussed below this species is here cirumscribed somewhat arbitrarily and specimens are also included here from the humid eastern escarpment; a similar habitat distribution is found in Psychotria parkeri.

As noted by Bremekamp Psychotria reducta is very similar to Psychotria retiphlebia and Psychotria isalensis, and their distinctions are not entirely clear. Bremekamp separated Psychotria reducta from the other two species based on the drying color of the leaves, which he considered to have a golden tinge on their lower surfaces, along with the robustness of the stems and the number of flowers in the inflorescences. The specimens he included in Psychotria reducta are similar in the drying color of the lower leaf surfaces to Psychotria parkeri, as he noted, and Bremekamp then contrasted Psychotria reducta's color with the brown or olive-green lower surface that he described for Psychotria retiphlebia and Psychotria isalensis. However modern specimens of Psychotria parkeri vary in their lower leaf color depending at least in part on collection method (e.g., preserved with alcohol or not, dried quickly vs. slowly), and this does not seem to be a consistent species-level character. The thickness of the dried young stems he described was slightly different between Psychotria retiphlebia (1.2-1.9 mm diam. and longitudinally furrowed) and Psychotria islaensis (2.0-2.5 mm diam. and not distinctly costate), but Psychotria reducta linked these (1.4-2.2 mm diam. and longitudinally furrowed). Variation in degree of development of both furrows and ridges on young stems is seen in various Psychotria species, and these features are also sometimes apparently related to drying methods. The number of flowers per inflorescence also this no longer appears to be a consistent species-level character in Psychotria, at least not the small differences in number Bremekamp used. With Psychotria reducta separated from the other species by its dry leaf color, Bremekamp then separated Psychotria isalensis and Psychotria retiphlebia based on their leaf shape, and degree of development of the leaf scars, with the leaf scars well developed in Psychotria retiphlebia vs. not as well developed in Psychotria isalensis. Bremekamp described the leaves as linear-lanceolate or linear-oblanceloate in Psychotria retiphlebia, vs. narrowly obovate in Psychotria isalensis; the leaves of the type specimens of these two species actually seem quite similarly shaped, with those of the type of Psychotria retiphlebia less rounded on the sides and more acute at the apex than those of Psychotria isalensis. The upper surface of the leaves of the type specimen of Psychotria isalensis in fact have a similar color to the lower surface of the leaves of the type specimen of Psychotria reducta, but Bremekamp did not mention or discuss this. He also characterized Psychotria isalensis by its stipule lobes that are short and deltate, and separated it from Psychotria reducta by this character; however the type specimen of Psychotria isalensis has stipules with several different forms, including apparently entire, shortly lobed with rather narrow lobes that could be considered deltate, and in one case two dissimilar lobes, one short and deltate and the other long and filiform. Another specimen included in Psychotria retiphlebia by Bremekamp, Decary 7987, has stipules on the stem apices with filiform lobes that match those on the type specimen of Psychotria reducta, stipules on nodes just below the stem apices with very narrow to filiform lobes ca. 3 mm long, and stipules on lower nodes with short triangular lobes that appear to be the basal portions of filiform lobes from which the narrow top part has fallen. Thus, Bremekamp's characterization and separation of these three species is not entirely clear, and no additional characters have been seen that distinguish any apparent taxa within this group of specimens. Bremekamp classified only a few specimens of this group in Psychotria reducta, with many more included in both Psychotria isalensis and Psychotria retiphlebia; however, the name Psychotria reducta has been most frequently used subsequently.

These three species are provisionally and rather abitrarily separated here, as outlined in the key below. Further study may show there are fewer than three species, and/or that the name Psychotria reducta is synonymous with Psychotria parkeri. The name Psychotria tananarivana was based on two collections that Bremekamp identified as two different species, with one syntype included in Psychotria reducta and one in Psychotria retiphlebia. Bremekamp cited Hildebrant 3927 as the type of Psychotria tananarivana, fixing its identity as a synonym of Psychotria retiphlebia.