Abstract: In order to clarify the taxonomic status of fairy shrimps from Qiubei County of Yunnan Province at the molecular level, this study applied PCR amplification and sequencing methods to determine the COI gene (658 bp) and 18S rDNA gene (325 bp) sequences of 30 fairy shrimp samples. The BLAST similarity analyses based on NCBI database showed that COI gene and 18S rDNA gene sequences were highly similar to those of Streptocephalus sirindhornae, with identity values of 96% and 100%, respectively. Sequence analyses revealed that there were 15 parsimony informative sites and 22 variable sites that defined 8 haplotypes in the COI gene sequences and there was one parsimony informative site and one variable site that defined two haplotypes in 18S rDNA gene sequences. In addition, the genetic distances and phylogenetic relationships were analyzed based on the combined dataset including our sequence data and homologous COI sequences of some Anostraca families in GenBank. The results showed that: interspecific average genetic distance between fairy shrimps from Qiubei and Streptocephalus sirindhornae of family Streptocephalidae was 4.3%, being at intraspecific level; while interspecific average genetic distance between fairy shrimps from Qiubei and Thamnocephalus platyurus of family Thamnocephalidae was 21.1%, being at interspecific level. In addition, phylogenetic trees showed that fairy shrimps from Qiubei and Streptocephalus sirindhornae clustered together as a monophyletic clade, with support values of 100% and 72% on COI and 18S rDNA trees, respectively. These results mentioned-above indicated that the fairy shrimp species from Qiubei County of Yunnan Province was Streptocephalus sirindhornae of family Streptocephalidae,but was not species of family Thamnocephalidae. At the same time, it was suggested that COI gene is a more suitable marker than 18S rDNA gene for molecular identification of fairy shrimps.

Key words: fairy shrimp, COI gene, 18S rDNA gene, molecular identification