A new species, Callistosporium subpetaloideum is described from Guizhou province, China. The key characteristics of C. subpetaloideum are its depressed, subpetaloid, finely pubescent pileus, pruinose apexed central stipe, large elliptical spores up to 7 μm long and 5 μm wide, lacking cystidia and clamp connection. Phylogenetic analyses based on the internal transcribed spacer region indicated that C. subpetaloideum occupies an isolated position, while morphological characteristics have also been compared with other phenotypically similar species.