Coptosperma comprises 8 described species and apparently numerous undescribed species of shrubs and small trees found in various habitats of Madagascar. This genus is characterized by its interpetiolar, triangular to ovate or ligulate stipules; its generally tough-textured leaves; its cymose bracteate inflorescences that are terminal or infrequently borne shortly supra-axillary with the uppermost leaves; its homostylous flowers with 4-5 calyx and corolla lobes; its salverform, generally white corollas with the lobes contorted in bud; its exserted clavate stigmas; its bilocular ovaries with 1 ovule per locule; and its indehiscent fruits with the exocarp leathery to fleshy and generally 1 large seed that develops in one locule and has ruminate endosperm. Most of these species were previously included in Enterospermum, which was considered either a genus of Africa and Madagascar related to Tarenna, or included within Tarenna. De Block et al. (2001) demonstrated that the species included in Enterospermum are distinct from Tarenna, and that Coptosperma is an older, correct name for these species. Thus, Enterospermum is now a synonym of Coptosperma.
Coptosperma is very similar to Tarenna in general aspect and most of its characters. De Block et al. (2001) outlined the separation of these two genera in detail. Coptosperma can be recognized by its fruits with a single developed locule and a single generally rounded seed with the endosperm ruminate, at least near the hilum; additionally species of Coptosperma generally have several to many flowers borne in branched cymes. Tarenna has fruits with 2 to several generally somewhat flattened seeds with entire endosperm; additionally Tarenna often has one to a few flowers that are often borne on well developed pedicels or peduncles. Coptosperma apparently includes many more species in Madagascar than Tarenna. Also similar to both of these genera is Robbrechtia, which differs from both Coptosperma and Tarenna by its large salverform corollas, and can also be recognized by its combination of quite large stipules that are shortly united around the stem and relatively long calyx limbs. Paracephaelis is also similar to these genera; it has fruits similar to those of Tarenna but inflorescences similar to those of Coptosperma, and usually has soft-textured pilosulous leaves.
De Block (2007) noted that Coptosperma is very poorly known in Madagascar, where it has numerous species of apparently recent derivation. Here it also has much greater species, morphological, and ecological diversity than is found in Africa. De Block et al. (2001) detailed several aspects of the morphology of Coptosperma, including stipule morphology: the species can be separated into two general groups based on this character which is useful for identification. The majority of species have triangular to narrowly triangular, acute stipules; several other species have distinctive ovate to lanceolate or ligulate, obtuse to rounded stipules that are held erect and flatly pressed together in bud, and which have been described as "bec de canard" (i.e., duck-beak) stipules. Mouly & De Block (2008) presented a key to the Coptosperma species of the Comores, all three of which are also found in Madagascar.