Population genetic diversity of mud crab (Scylla paramamosain) in Hainan Island of China based on mitochondrial DNA

► We analyzed genetic diversity of S. paramamosain from Hainan Island using COI sequence. ► A total of 32 different haplotypes and 32 polymorphic sites were found. ► Haplotype H4 was present in all localities but others existed in one or two individuals. ► No significant genetic differentiation among six localities was found. ► Neutrality tests and mismatch analysis implied a potential population expansion event.