Pseudomantalania is very similar to Mantalania and in general replaces it at higher elevations, for more information see the Mantalania page. Pseudomantalania is characterized by its habit as an unbranched shrub or small tree with the leaves clustered at the stem apex where the internodes are hardly developed; its relatively large narrow leaves produced in whorls of 7-9(-21?); its relatively large triangular stipules; its subsessile, axillary, congested-cymose inflorescences with numerous large flowers; its funnelform, purple to pink corollas with the lobes 5 and contorted in bud; its ovaries that are originally 1-locular and later become 2-locular (Leroy 1974: p. 43) with parietal placentation; and its large fleshy fruits with the numerous seeds embedded in pulp. The flowers are apparently bisexual, and the fruits become relatively large and thickly fleshy (to 8 x 5.5 cm when dry) although the color and other field characteristics have apparently not been noted. Pseudomantalania macrophylla was apparently originally suggested to be a species of Mantalania by Capuron, but Leroy first formally published the name for this and separated it from Mantalania.
Leroy (1974) presented a detailed study of Pseudomantalania and treated one accepted species, Pseudomantalania macrophylla. He also discussed one unusual specimen, which he called "Pseudomantalania cf. macrophylla" and suggested might represent a distinct species. This specimen is Perrier 4589 (P) from Massif du Manongarivo, Montagnes de Sambirano, ca. 2000 m, which is generally within the geographic range of Pseudomantalania macrophylla. Leroy noted that this unusual specimen had only flower buds and immature fruits and thus could not be conclusively identified, but differs from Pseudomntalania macrophylla in its leaves in whorls of 9(-21?), its calyptrate rather than interpetiolar stipules, its smaller flowers borne on developed pedicels, and its truncate calyx limbs. The status of this specimen or plant has apparently not been evaluated since Leroy's study.