What is "phymosteus"

Phymosteus liui is a large selenosteid arthrodire placoderms known from the Lower Famennian Xiejingshi Formation of Shimen County, Hunan province, in central China.

The holotype and only known specimen of P. liui is a V-shaped median dorsal plate with a distinctive nubble texture. Because of the fossil's obviously incomplete nature, its exact relationship to the other selenosteids can not be satisfactorily determined beyond the fact that it was related to them.