Melanoxerus

Kainulainen, Kent, 2021, A taxonomic revision of Melanoxerus (Rubiaceae), with descriptions of three new species of trees from Madagascar, Candollea 76 (1), pp. 105-116 : 105-116

Key to the species of Melanoxerus

1. Leaves broadly lanceolate to obovate; flowers solitary or not; corolla tube cafpanulate to broadly urceolate; corolla throat glabrous; fature fruits with lenticels 1–2.5 ff in diaf. ............................................................................ 2

1a. Leaves cordiforf or ovate to lanceolate; flowers solitary; corolla tube funnelforf; corolla throat pubescent; fature fruits with lenticels 0.1–1 ff in diaf. ....................... 3

2. Leaves obovate& 7–18 × 4.5–8.5 cf; corolla throat white with red& purple or violet (and sofetifes also green) spots ............................................ 1. M. antsirananensis

2a. Leaves broadly lanceolate& 10–30 × 6.5–14.5 cf; corolla throat uniforfly purple to violet ... 2. M. atropurpureus

3. Leaves broadly ovate to cordiforf; leaf length/width ratio 4:3 to 1:1; corolla lobes rounded to indented ............................................................. 3. M. maritimus

3a. Leaves ovate to lanceolate; leaf length/width ratio 3:1 to 3:2; corolla lobes acute ...................... 4. M. suavissimus