Platysace kochii (E. Pritzel) L.A.S. Johnson is here transferred to Xanthosia as X. kochii (E. Pritzel) J.M. Hart and Henwood comb. nov. (Mackinlayoideae, Apiaceae). Xanthosia bungei Keighery is reduced to the synonymy of X. kochii. A lectotype for X. kochii is chosen and the typification of X. fruticulosa adjusted. Descriptions of X. kochii and X. fruticulosa, a distribution map, and diagnostic images are provided.