Abstract: 【Aim】 To sequence the COⅠ and ITS2 sequences of the Culex species (subspecies) with distribution record in China, and to construct and discuss the molecular phylogenetic relationships among these species (subspecies). 【Methods】 COⅠ and ITS2 sequences of a total of 20 Culex species (subspecies) were newly sequenced, and COⅠ sequences of other 20 Culex species (subspecies) and ITS2 sequences of other three Culex species (subspecies) were downloaded from NCBI databases. The base composition, interspecific genetic distance and saturation analysis of COⅠ of 40 species (subspecies) and ITS2 sequences of 23 species (subspecies) were analyzed, and the incongruence length difference (ILD) test was conducted for COⅠ+ITS2 sequences. The phylogenetic relationships of these Culex species (subspecies) were inferred using maximum likelihood (ML), Bayesian interference (BI), neighbor joining (NJ) and maximum parsimony (MP) based on the nucleotide sequences of two molecular data sets (COⅠ and ITS2), respectively. Kishino-Hasegawa (KH) and Shimodaira-Hasegawa (SH) tests were used to evaluate the differences of these four phylogenetic trees constructed, and the most reasonable phylogenetic tree was selected. 【Results】 The newly sequenced COⅠ and ITS2 sequences are 625-685 and 300-559 bp in length, respectively. The pairwise genetic distances among Culex mosquito species (subspecies) range from 0.002 to 0.198 for COⅠ and from 0.006 to 1.807 for ITS2. The ILD test of COⅠ+ITS2 sequences of 23 Culex species (subspecies) showed that the data set was incompatible, so COⅠ+ITS2 sequences were inappropriate to construct the phylogenetic trees of these species (subspecies). By KH and SH tests among these four phylogenetic trees, the BI tree based on COⅠ sequence was the most reasonable tree, while the MP tree based on ITS2 sequence was the most reasonable tree. The BI tree constructed based on the COⅠ nucleotide sequences showed that all members, except for Cx. infantulus and Cx. brevipalpis of the same subgenus, are clustered together, which is consistent with the traditional morphological classification. Both the subgenus Lutiza and Barraudius are grouped into the subgenus Culex. The subgenus Maillotia and subgenus Nexoculex are grouped together. The subgenus Culiciomyia, subgenus Eumelanomyia and subgenus Lophoceramyia are monophyletic. The MP tree based on the ITS2 sequences showed that the relationships between subgenera and species (subspecies) are chaotic. 【Conclusion】 The molecular phylogenetic tree reconstructed shows that the subgenus Culex is not a monophyletic group. Compared with ITS2 and COⅠ+ITS2, COⅠ is a more desirable molecular marker for the reconstruction of the phylogeny of Culex species. The molecular phylogenetic relationships reconstructed in this study lay a foundation for studying the phylogenetic relationships among subgenera and species (subspecies) of the genus Culex in China.

Key words: Culicidae, Culex, molecular marker, COⅠ, ITS2, phylogeny, China