Taxonomy And Molecular Phylogeny Of The Family Megascolecidae Earthworms From China

Earthworms belonging to the Family Megascolecidae are the most important and widely distributed in China.Taxonomy and molecular phylogenetic analysis are of important value to understand their phylogeny.In this study,we collected earthworms from twenty more nature reserves and nearby places in 2010-2013,to research species diversity of China.After extracting and sequencing mitochondrial genes COI,COII,ND1,12S&16S,the phylogenetic trees were constructed by Maximum Likelihood method and Bayesian method respectively.Combined morphologic and molecular result reveals the evolution of the Family Megascolecidae.The main result as follows:1.321 species of the Family Megascolecidae were collected,in which 270 species are new.There are 263 species in Genus Amynthas,57 species in Genus Metaphire,1 species in Genus Perionyx.And,224 new species in Genus Amynthas,46 new species in Genus Metaphire.The checklist of the Family Megascolecidae from China was updated.A total of 571 species are in record until June,2016.There are 436 species in Geus Amynthas,125 species in Geus Metaphire,10 species in other genera.2.Taxonomy and molecular phylogeny are complementary studies.All of the mitochondrial genes(COI,COII,ND1,12S&16S)sequenced could be used as barcodes,as partitive standard of 16S gene is lowest.In the species level,the main partitive standard of COI gene is(14.0,24.0),12S gene is(12.0,24.0),and(12.0,22.0)for the combined 5 genes while the mean is 17.2±0.7%.The main partitive standards are propitious to estimate molecular identificationBut there are more phylogenetic information in the 12S and 16S genes,as their R(Ts/Tv)is lower than the protein-coding genes.This study revealed that combined 5 genes is most suitable for constructing phylogenetic trees,and 12S+16S,12S+16S+ND1 also have great value in phylogenetic analysis3.The objective phylogenetic trees of the Family Megascolecidae from China,based on the 5 genes(COI,COII,ND1,12S&16S)of 584 specimen,were constructed Phylogenetic relationships among different species of the Family Megascolecidae revealed by taxonomy and molecular phylogeny analysis.The phylogenetic result shows that Genus Perionyx is large difference from Genus Amynthas and Metaphire;Genus Amynthas or Metaphire are not monophyletic;and species-group is also not monophyletic.Taxonomic system of the Family Megascolecidae should be reconstructed4.The divergence times of groups and species were estimated by Bayesian method based on lognormal relaxed clock.Ancestral area analysis and ancestral character analysis of the Family Megascolecidae had been reconstructed.According to the result,the ancestors of Megascolecidae from China originated on Early Jurassic period,and started diverging on the Late Cretaceous.The ancestors of Pheretimoid earthworms were stems largely from Late Cretaceous to Early Cenozoic(?65.32Ma).Species richness increased sustainedly during Cenozoic period.This work could conjecture Genus Metaphire originated no later than Early Miocene,and many sub-species and parthenogenetic species are traceable from Middle or Late MioceneOn the basis of ancestors area reconstructed and spread route analysis,the study surmised the ancestors of Megascolecidae might come from Indo-China Peninsula,and then spread throught China in lengthy geologic time.The ancestors of Group 8-10,as main Megascolecidae earthworms of Hainan Island,spread from mainland on Early Eocene(?50.60Ma),and then diverged in the island generallyOverall,the ancestors of Megascolecidae which originated on Early Jurassic period,spread to China and evoluted different morphological character types.The species diversity of Megascolecidae earthworms derives from this.