A synopsis of the genus Cynoglossum L. (Boraginaceae) in Madagascar and the Comoro Islands

The species of Cynoglossum L. known from Madagascar and the Comoro Islands are revised and six species are recognized from the region. Cynoglossum Lanceolatum is a widespread species that is common throughout Madagascar and also Africa and Asia; C. cernuum occurs in Madagascar and the Mascarene Islands, but the other four species are endemic to Madagascar, three of which (C. birkinshawii, C. lowryanum, and C. tsaratananense) are described as new. Of the six species of Cynoglossum known from Madagascar and the Comoro Islands, four face significant threat of extinction and three are critically endangered.