Bazzania konratiana sp. nov. is described from Mananara Nord Biosphere Reserve and National Park. The new species was collected from a wet lowland rainforest where annual rainfall reaches 3500 mm. It differs from the similar Bazzania approximata Onraedt, an endemic species from Seychelles, in its overall larger size, the thick-walled leaf cells with large bulging trigones and proportion of hyaline and chlorophyllose cells in the underleaves.