Cyathostemon ambiguus is a member of the family Myrtaceae endemic to Western Australia.
It is found in an area along the south coast extending from the Great Southern and into the south western Goldfields-Esperance regions of Western Australia.
Cyathostemon ambiguus was first described in 1869 by Ferdinand von Mueller as Astartea ambigua,[1] but in 2012 was transferred to the genus, Cyathostemon, by Barbara Rye and Malcolm Trudgen.