A Preliminary Classification On Cloeoninae Of China

The nymphs of mayfly subfamily Cloeoninae(Insecta:Ephemeroptera:Baetidae)typically live in lentic water and have unique ecological niche.Because of their high species diversity,small to tiny body size,uniform imaginal bodies and limited classification features,this group of mayflies is very difficult to research and is rarely reported in China.Furthermore,in recent decades of years,the classification characteristics of them and the Baetidae have been shifted from those of imagos to nymphs.Consequently,the association between adults and nymphs is absolutely important for Chinese species in the taxonomic study on this subfamily.Using DNA barcoding method(COI gene as markers)plus indoor rearing nymphs to adults and character matching,we preliminarily identify 3 genera 30 species based on the materials from 23 provinces and municiples of China.Among them,15 species are new to science and 6 others are new to China.One species,Procloeon simile(Eaton,1870)comb.nov.,is transferred from the genus Cloeon.One synonym:Cloeon viridulum Navas,1931(=Cloeon pielinum Navas,1933,New Synonym)is proposed.Moreover,the adults and nymphs of 17 species are successfully associated.Ecologically,the species Cloeon viridulum are observated for nearly one year to know more about their life and affecting factors.The data shows it can maturate from June to September.Food and temperature are important factors to its population dynamics and distribution.Besides,the degree of feeding on vegetable is closely related to their habitat,population density,individual body size and season.The K2P genetic distances between partial COI gene sequences of different populations are calculated and phylogenetic trees are also reconstructed with using Neighbor-Joining and Bayesian Analysis methods.The topologies show that in Cloeoninae,the intergeneric genetic distance is 0.185 to 0.202,that of species is from 0.099 to 0.159,and the average intraspecific genetic distance is 0.000 to 0.016.All samples of same species are grouped together with high supporting index.The genus Centroptilum diverges away from others first,while genera Cloeon and Procloeon have very close relationship in the trees.