Three hundred twenty-six sampled individuals were assayed to study the genetic diversity and polymorphisms based on the SSR markers. All analyzed markers were polymorphic, and 287 alleles were identified, with 15.94 alleles per locus detected. The polymorphism information content (PIC) values ranged from 0.71 to 0.93, with an average of 0.87, which indicates that the markers were highly informative. Based on the unweighted pair-group method with arithmetic mean (UPGMA) cluster analysis, we found that the 18 species were divided into two clusters. M. italicus and M. speciosus from cluster A and M. indicus and M. segetalis from clusterB were closely related. Population structure analysis suggested that the optimum number of groups was three. From the analysis of molecular variance, 17.79% of the variance was due to species difference , 31.61% of the variance was due to differences among populations within species and the remaining 50.60% was due to differences within populations.