For more information on this genus, see the TROPICOS Rubiaceae Project. (To access that data, in the upper right of this web screen, click on "Choose Project", and then the corresponding database from that list.)
According to Taylor & Rogers (2013), the total number of indigenous Danais species known from Madagascar is 34. Two additional species (D. aptera and D. baccata) were treated by Puff & Buchner (1994) as status unclear and may bring the total amount species for Madagascar up to 36. Also, Puff & Buchner excluded Sabicea verticillata Wernham from Danais, even though its type and only known specimen was subsequently annotated in this genus, but this specimen certainly seems to belong to Danais. These two vining genera differ in particular in their fruits, baccate in Sabicea vs. capsular with winged fruits in Danais, and Puff & Buchner pointed out that notes on this type specimen mention its winged seeds. However they also pointed out that this specimen clearly does not have fruits so the origin of this description is not clear. This specimen does agree with Danais and differ from Sabicea in its stipules that are short-bodied and closely revolute along with its corollas with a narrow tube that abruptly flares or inflates near its top, vs. stipules generally longer-bodied and erect to spreading and the corolla tube cylindrical or funnelform in Sabicea.