1. Two or more sepals or petals fused to the mid-point or more, petals and sepals 11-15 mm.................................. 2
1a Sepals or petals adnate in the basal third or less but none of them fused to the mid-point, petals and sepals 5-8 mm long................................................................................. 3
2. Lateral sepals fused to the mid-point, other sepal and petals free to the base or fused to a fifth of their length; column with short recurved triangular apical arms, broader than long and acute at the tips; sepals and petals white up to 15 mm long; lip with a low basal bilobed callus and strongly upcurved sides......................... D. avaratraensis
2a All sepals and petals fused to the mid-point; column lacking apical arms; sepals and petals white, up to 12 mm long; lip flabellate, orbicular, distinctly clawed, apex of claw bearing a reflexed or retrorsely placed ligule-like callus....................................................................................... D. africana
3 Column lacking apical arms; lip 3-lobed at the tip, with two lines of verrucose warts along length; sepals and petals white............................................................ D. verrucosa
3a Column with recurved apical arms that are bilobed at the tips; lip broadly obovate-spatulate, lacking rows of warts, with sides only slightly upcurved, and a tall apically trilobed callus at the base; sepals and petals white, pink or brown........................................................... D. recurvata