In this study, morphological and molecular phylogenetic approaches were used to investigate the species diversity of Cryptothecia and Myriostigma from southern China. We found four new species of Cryptothecia and Myriostigma (C. disjecta, C. sorediatum, M. melanovillosa and M. visus-blotch). Cryptothecia disjecta is distinguished by verrucose pseudisidia that are loosely scattered on the thallus, the upper parts of which are white or have darker dots. Cryptothecia sorediatum is distinguished by I– medulla and thalli having globose soralia. Myriostigma melanovillosa is distinguished by thalli with black or purple dots and hyaline to pale yellow ascospores (63–71 × 26–33 µm). Myriostigma visus-blotch is distinguished by hyaline ascospores and ascigerous areas, which have many irregular small patches that are scattered or clustered together radially elongated. In addition, a phylogenetic tree based on mtSSU, RPB2 and nuLSU illustrates the phylogenetic placement of the proposed four new taxa. Detailed descriptions of the morphological, ecological and chemical characteristics and illustrations of each species are provided. Two updated keys for all known Chinese Cryptothecia and Myriostigma species are also provided. Key words: Diversity, identification key, Lichenized fungi, taxonomy.