Because Jack's name has priority, "R. arnoldii" should technically be a synonym of "R. titan", but at least in Britain, it was common at the time to recognize the names introduced by well-regarded scientists such as Brown, over what should taxonomically be the correct name. This was pointed out by the Dutch "Rafflesia" expert Willem Meijer in his monographic addition to the book series "Flora Malesiana" in 1997. Instead of sinking "R. arnoldii" into synonymy, however, he declared that the name "R. titan" was "incompletely known": the plant material used by Jack to describe the plant has been lost.