A synoptic revision of the Squamosa group of Diospyros L. (Ebenaceae) in Madagascar and the Comoro Islands is presented in which nine species are recognized, including six new species that are described and illustrated (Diospyros antakaranae Capuron ex G.E. Schatz & Lowry, sp. nov., Diospyros betamponensis G.E. Schatz & Lowry, sp. nov., Diospyros callmanderi G.E. Schatz & Lowry, sp. nov., Diospyros darainensis G.E. Schatz & Lowry, sp. nov., Diospyros phillipsonii G.E. Schatz & Lowry, sp. nov., and Diospyros sennenii G.E. Schatz & Lowry, sp. nov.). A key to the species is provided, along with an IUCN risk of extinction assessment for each species. Five species are assessed as Endangered (D. betamponensis G.E. Schatz & Lowry, sp. nov., D. callmanderi G.E. Schatz & Lowry, sp. nov., D. darainensis G.E. Schatz & Lowry, sp. nov., D. phillipsonii G.E. Schatz & Lowry, sp. nov., and D. tetraceros H. Perrier), one as Vulnerable (D. antakaranae Capuron ex G.E. Schatz & Lowry, sp. nov.), one as Near Threatened (D. comorensis Hiern), and two as Least Concern (D. sennenii G.E. Schatz & Lowry, sp. nov. and D. squamosa Bojer ex A. DC.).