Abstract
A taxonomic revision of all native Myrtaceae genera (Eugenia and Syzygium) of the Comoros is presented based on herbarium specimens and molecular and palynological evidence. Eight native species are recognised, seven of which are endemic to the archipelago. We describe the following five new native species: Eugenia choungiensis, E. pascaliana, Syzygium comorense, S. labatii, and S. tringiense. Eugenia anjouanensis is reduced to synonymy under E. comorensis. Lobed stigmas are reported for the first time in Eugenia and only the second time in Myrtaceae. Androdioecy is reported in Eugenia for the first time outside of continental Africa, and its reproductive system is discussed in light of our findings. Preliminary conservation assessments for each native species are calculated according to IUCN Red List criteria, with the majority being threatened with extinction. Recent fieldwork coupled with widespread habitat conversion in the vicinity of the only known specimen suggests strongly that S. humblotii is now extinct.