Description of four new species of Monodora and Isolona (Annonaceae) from Tanzania and an overview of Tanzanian Annonaceae diversity

Four new species of Annonaceae from Tanzania are described and illustrated: Monodora carolinae, from coastal Tanzania and northern Mozambique, with reflexed outer petals and inner petals connivent by their tips; M. globiflora, endemic to the montane forests of the Udzungwa Mountains, with inner petals fully connivent as a globe over the receptacle; M. hastipetala, endemic to the Kiwengoma Forest (Matumbi Hills), with hastate inner petals acuminate at apices; and Isolona linearis, endemic to Iringa region, with linear corolla lobes. Keys are provided to all species of both genera for East Africa. Pollen morphology and tectum structure are indicated for every new species, and evolutionary trends are discussed for Isolona. Finally, an overview of Tanzanian Annonaceae is given, with a species checklist and distributional maps of species and genera, based on data gathered from literature and the MO and WAG herbarium databases. Most Annonaceae biodiversity is confined to the Eastern Arc and Coastal Forests, underlining once again the importance of these endangered regions.