Four species of endemic Leptobrachium are known from Borneo, two lowland species L. kanowitense and L. abbotti, a montane species L. montanum, and a highland species L. gunungense. Of these, both L. montanum and L. abotti were found to contain several cryptic species by recent molecular studies. The population from Bario, Kelabit Highland of Sarawak, is one such cryptic species and was once called Lineage 2 of L. abbotti. Our morphological survey on this population proved that it has characteristics distinct from all other congeners, and therefore, we describe the Bario population as a new species, Leptobrachium kantonishikawai sp. nov. The new species is distinguished from putative topotypes of L. montanum and L. abbotti, as well as from L. gunungense by having a grayish brown abdomen, usually vermiculated, although sometimes spotted or blotched with white, and some unique morphometric characteristics.