Tarenna madagascariensis is rather frequently collected and morphologically variable, it was formerly known by a later synonym Tarenna grevei. It is characterized by small to medium-sized rather papery leaves; triangular stipules; rather lax, terminal, cymose inflorescences with several flowers on well developed pedicels; a short calyx limb that is lobed for up to about half its length with the 4 lobes usually ligulate to ovate; a medium-sized corolla with 4 lobes and the anthers and stigmas exserted; and subglobose rather small fruits. The leaves vary from broadly elliptic to quite narrowly elliptic-oblong. The plants sometimes have a rather unusual branching pattern, with the lateral stems markedly supraaxillary (e.g., De Block et al. 1221). The "African" portion of the geographic range that is sometimes cited for this species is Aldabra Island. This species has sometimes been collected on sand and on tsingy, and in addition to the protected areas listed above has also been collected in the Botanical Garden of the Ampijoroa Forestry Station. Only one specimen (De Block et al. 949) gives the habitat of this species as humid forest.
Tarenna madagascariensis is very similar to and sometimes sympatric with Coptosperma nigrescens. De Block (2005: p. 113) discussed their separation in detail. Among other differences, Tarenna madagascariensis has in each fruit two usually planoconvex seeds with entire endosperm and a large circular indentation and corollas about 10-15 mm long with four lobes, while Coptosperma nigrescens has in each fruit one subglobose seed with deeply ruminate endosperm and a rugose or smooth seed coat and corollas about 8-10 mm long with five lobes. Tarenna madagascariensis is also very similar to Tarenna sechellensis, which is separated only by the number of ovules in the ovary locules and perhaps reproductive biology; see the page for Tarenna sechellensis for more details.
A number of the currently associated specimens that appear on this page have 5-merous flowers and should be excluded (possibly to be referred to Coptosperma nigrescens Hook.f. as suggested by De Block (2005).