Diploschistes tianshanensis is described as a new species, found on rotten wood with mosses and other lichens (Cladonia sp.) in an arid region of Northwestern China. The new fungus, which is diagnosed by urceolate ascomata and large ascospores, resembles D. gypsaceus but is readily distinguished by its epruinose thallus surface. ITS rDNA sequence analyses support the taxon as a distinct species. The description of D. tianshanensis is accompanied by notes on its chemistry, distribution and ecology, and comparison with related species. Key words—Central Asia, biodiversity, Graphidaceae, Ostropales, taxonomy.