Strain DMKU-RK359T, representing a novel yeast species, was isolated from the external surface of a sugar-cane leaf collected in Thailand. On the basis of morphological, biochemical, physiological and chemotaxonomic characteristics, sequence analysis of the D1/D2 region of the large-subunit (LSU) rRNA gene and the internal transcribed spacer (ITS) region, strain DMKU-RK359T was assigned to a novel Wickerhamomyces species. The novel species was closest to Wickerhamomyces ciferrii, but differed from it by 0.7 % nucleotide substitutions in the D1/D2 region of the LSU rRNA gene and 6 % nucleotide substitutions in the ITS region. The name Wickerhamomyces siamensis sp. nov. is proposed (type strain DMKU-RK359T = BCC 50732T = NBRC 108900T = CBS 12570T).