Additions to Orophea subgenus Sphaerocarpon (Annonaceae): revision and transfer of Mezzettiopsis

The genus Mezzettiopsis Ridl. (Annonaceae) is revised and transferred to Orophea Blume subgenus Sphaerocarpon Keßler. Phylogenetic analysis of subgenus Sphaerocarpon and Mezzettiopsis places Mezzettiopsis within the subgenus. Furthermore, the prevalence of common or overlapping character states and the paucity of unique character states necessitate the transfer. Two species were transferred from Mezzettiopsis. Of these, one species of Orophea is reinstated and one new combination is made. Three species are described as new. In total, nine species are fully described. Sphaerocarpon is a subgenus of small, tropical, lowland trees distributed from Sulawesi westwards to South India. It is characterised by having sepals and outer petals that are sessile or nearly sessile and more or less ovate, with outer petals that are twice the size of the sepals, inner petals that are clawed, roughly diamond-shaped and connivent during development at the edges of the lamina, by miliusoid stamens, by stipitate, globose to oblongate carpidia, and by glabrous to pubescent leaves. A key to the flowering material is presented.