Based on the comparative morphological and molecular characteristics of five strains of Trichodina reticulate, redescription of this species was conducted in the present study (Fig. 1﹣3, Table 2). The results indicated that these five strains showed different phenotype differentiation patterns including different denticle morphologies and the presence or absence of central granules, thus this species has dominant intraspecific morphological diversity. However, the sequence similarity and genetic distance among the five strains of T. reticulata were 99.0%﹣100% and 0.000﹣0.008, respectively, and their major variation areas (V4, V5 and V7) of 18S rDNA possessed a consistent secondary structure (Fig. 6, 7), which suggests that genetic distances among these different strains are within the intraspecific level. Furthermore, the analysis of intra-species divergence on the basis of 18S rDNA and ITS-5.8S rDNA variation site and phylogenetic tree (Bayesian inference, BI tree and maximum likehood, ML tree) showed that these strains of T. reticulata with different geographical distributions and hosts were clustered into one clade mainly due to the same mutation site (Fig. 4, 5 and 8, 9), suggesting that the intraspecific differentiation for T. reticulata probably is mainly influenced by their genes, rather than the environmental factors including geographic distribution and host type. Besides, the present study confirmed that central granules should not be the main characteristics for species identification in T. reticulata.