Remarks on the tropical Asian and Australian taxa included in Diplospora or Tricalysia (Rubiaceae — Ixoroideae — Gardenieae)

The Asian and Australian species generally included in Diplospora or Tricalysia are shown to form an artificial assemblage. A few species even do not belong to the Gardenieae-Diplosporinae and need to be transferred to other tribes of the Ixoroideae. So Diplospora malaccensis, Diplospora minahassae, Tricalysia purpurea, and Tricalysia sorsogonensis belong to the Hypobathreae. The three Australian Diplosporas are members of the Pavetteae and are transferred to Tarenna. A survey is given of the characters of the remaining Asian species of Diplospora/Tricalysia, demonstrating that 1) these species cannot be accommodated under the African genus Tricalysia, and 2) Discospermum, since a century included in the synonymy of Diplospora, merits to be revived at generic rank. The two genera differ in placentation, fruit size and fruit wall texture, number of seeds per locule, seed shape, and exotestal cell anatomy. Eight necessary new combinations are provided: Diplospora puberula, Diplospora tinagoensis, Discospermum abnorme, Discospermum beccarianum, Discospermum whitfordii, Tarenna australis, Tarenna cameroni, and Tarenna triflora. An annotated check-list including the more than 100 names involved is given.