Molecular Identification Of Corynoneura Group(Diptera,Chironomidae)from Southern China

The family Chironomidae(Diptera)is a well-known indicator of freshwater biomonitoring and paleolimnology studies,where they often exhibit high diversities and abundances.Although some larger species had been widely used in ecological researches,the tiny species(< 2 mm)of the chironomids are often ignored by ecologists and limnologists,which hinders the developing progess of some related subjects.Aiming to make accurate identifications of these tiny insects and confirm their status in the ecosystem,based on the material collected from southern China,three genera(Corynoneura,Thienemanniella and Onconeura)with clavus wing in the adult were first sorted and identified based on classical morphological methods,then the partial corresponded remains or preserved fresh material was used for the molecular analysis.Two molecular markers,nuclear protein-coding gene CAD and mitochondrial protein-coding gene COI were selected to delimit those similar sibling species.Totally 35 species(including seven cryptic species)were identified and described,of which nine new species,10 unnamed species are noted.In addition,three synonyms and one new combination are proposed,five species was successfully associated with their immature stages.The genus Onconeura originally recorded only in the Western Hemisphere,is first recorded here,while the monophyleticity is needed to be clarified further.All the amplified 215 gene sequences from 100 individuals,including 100 COI sequences,64 CAD1 sequences,and 51 CAD4 sequences were submitted to BOLD database.The results of Neighbor joining method and Maximum likelihood method based on COI sequences and CAD sequences,showed a consistency of delimitation on specieslevel.The CAD processed a stronger phylogenetic signal than COI.The results of the Genetic distance analysis based on COI sequences exhibited that the average intraspecific and interspecific genetic distance of Corynoneura group was 3.2% and 15%,respectively.There is an overlap between the maximum intraspecific and the minimum interspecific genetic distance.Certain cryptic species complexes,which are hard to separate from each other based solely on males,need further associated material to be resolved.