The hylocitrea (Hylocitrea bonensis), also known as the yellow-flanked whistler or olive-flanked whistler, is a species of bird that is endemic to montane forests on the Indonesian island of Sulawesi. It is monotypic within the genus Hylocitrea, and has traditionally been considered a member of the family Pachycephalidae, but recent genetic evidence suggests it should be placed in a monotypic subfamily of the family Bombycillidae, or even its own family, Hylocitreidae.