In his paper on the peat swamp forests of Sarawak and Brunei (Gard. Bull. 20, 1963, 152) Dr. J. A. R. Anderson made notice of a distinctive Xanthophyllum species which he was not able to identify. In 1968, Mr. F. S. P. Ng, revising the genus for the Manual of Malayan Timber Trees, recognized it as a new species, but did not describe it. Working now on a monograph of the genus, and having examined all collections Dr. Anderson kindly sent on loan to me, I am able to describe it here as a new species. I am much indebted to Dr. H. Sleumer for rendering the diagnosis in Latin.