Taxonomic And Phylogeneic Study On The Genus Culex (Diptera:Culicidae) From Southwestern China

Mosquitoes of the genus Culex (Diptera:Culicidea) are distributed worldwide. Up to now,82species have been reported from China, which are classified into9subgener. Many species in the genus are important medical insects. Many species are actually in distinguishable in morphology (cryptic species, considered complex), which has seriously hindered the study of taxonomy and phylogeny. The fauna and species of Culex have greatly changed with the changes in natural environment and climate in the past decade, and the phylogenetics of the genus is still unresolved. Therefore, further investigations will be needed using molecular markers to elucidate the phylogeny of the genus Culex.This study reviewed the morphology, phylogeny, and molecular taxonomy of Culex in China based on the literature, and revised the list and cited references. In the meantime,20Culex species (1319mosquitoes) were identified by morphological examination. They were collected from many distributed sites in4provinces of Southwest China from2010-2013. Then mitochondrial DNA was extracted from40Culex mosquitoes and used for COI amplification and sequencing.40COI sequences of Culex were obtained by BLAST analysis. Nucleotide composition and phylogenetic relationship were further analyzed. Twenty of forty sequences combined with12Culex COI sequences retrieved from GenBank were used for phylogenic analysis. A Minimum Evolution (ME) tree was constructed by MEGA5.0using Aedes africanus as the outgroup. Then, genetic relationship and taxonomic status of the genus Culex in China were inferred based on the phylogenetic tree.The conclusions are as follows:①The new species list of Culex in China (up to2012) consists of9subgenus and82species, with the addition of7species, Culex pseudoguizhouensis, Culex megaonychus, Culex oresbius, Culex aestivus, Culex hirtipalpis, Culex viridiventer, and Culex cheni, and the detailed references and distribution information for all82species were provided. ②Based on literature and specimens of Culex, a geographical fauna analysis in China was conducted. The results show that71species are distributed in the Oriental region,66species in southwest China (19species are found to only exist in the southwest China) and accounts for86.6%,80.5%(23.3%) of all known Culex species in China. All66species reported in southwest China are distributed in Yunnan province.20species were collected and identified in this study, including1newly recorded species from Yunnan (this species has been earlier reported only in northeast China and Taiwan). The results showed that the distribution of mosquitoes is changing with environmental change.③Morphological taxonomy results were further confirmed by mtDNA COI sequencing and analysis. Sequence and phylogenic analysis revealed some inconsistencies between morphological and molecular taxonomy. There is a need for further study for morphological and moleculat studies to elucidate these issues.④The phylogenetic tree based on33species of mtDNA COI showed that the Pipiens group and the Sitiens group are claded to a branch, the subgenus Culiciomyia can gather for a branch. It supported the view by Bruna Demari-Silva that Culex Bitaeniorhynchus group should not be promoted to the subgenus Oculeomyia. The result also revealed that Culex fuscannus is a single species. The reason may be due to the members of this subgenus in this study are less, so this subgenus evolutionary needs further study.Type specimens of the investigated species are all deposited in the Institute of Entomology and Molecular Biology of Chongqing Normal University.