Phylogenetic Relationship Of The Tribe Scymnini From China (Colerptera: Coccinellidae)

The tribe Scymnini belongs to the family Coccinellidae within the suborder Polyphaga,order Coleoptera.Members in this tribe are feeding on aphids,mealybugs and whiteflies,which is one of the most important natural enemies in biological control.Although one of the best studied groups of Coccinellidae,the taxonomic system of Scymnini lacks detailed revision,its taxonomic status remain in dispute.Moreover,the phylogenetic relationship among genera in this tribe is poorly understood.Those problems now heavily restricted the development of the taxonomy of Coccinellidae.In order of solve these problems and establish a reasonable classification system,more research is needed to further refine the taxonomic status of the tribe Scymnini.In the present paper a comprehensive phylogenetic analysis of Scymnini based on three mitochondria genes COI,COII,Cytb and five nuclear genes CADI,CADII,Wingless,TOP and H3 is conducted with Maximum likelihood and Bayesian inference methods.Meanwhile,some species of Sticholotini,Chilocorini,Ortaliini,Aspidimerini,Coccidullini,Coccinellinae and Epilachnini were selected as outgroup to discussion the phylogenetic relationship between Scymnini and other coccinellid in the level of tribe.Result of sequence analysis indicated: three mitochondria genes A+T content apparently higher G+C content;the ratio of transition and transvertion more than 1 of three mitochondria genes and the ratio of transition and transvertion less than 1 of five nucler genes;the average genetic distance among the Scymnini was 0.195 based on combined dataset.Phylogenetic analysis indicated: the tribe Scymnini and the genus Scymnus Kugelann were paraphyletic,whilst the genera Axinosymnus Kamiya,Sasajiscymnus Vanderberg,Nephus Mulsant and Horniolus Weise were monophyletic.Genus Axinoscymnus Kamiya was identified as the sister-group of the Rodolia Mulsant and the Cryptolaemni was identified as the sister-group of the Epilachnini for the first time.In the genus Scymnus Kugelann,the subgenera Scymnus(Scymnus)Kugelann and Scymnus(Parapullus)Yang were monophyletic and the subgenus Scymnus(Neopullus)Sasaji was nested deeply within the subgenus Scymnus(Pullus)Mulsant clade,nevertheless another the subgenera Scymnus(Orthoscymnus)Canepari shows farther blood relationship in other subgenera of Scymnus.So we revised classification of Scymnus,with only retain Scymnus(Scymnus),Scymnus(Parapullus)and Scymnus(Pullus)within Scymnus and the Scymnus(Orthoscymnus)were promoted as genus level.In addition,the tribe Oratliini was identified as the sister-group of the tribe Aspidimerini for the first time.