Diversity Of The Benthic Polychaeta In China Seas

Polychaeta is a common and dominant group of marine macrobenthos.The classification system of Polychaeta has undergone many changes because of the rich diversity.However,molecular technology provides a new insight for the phylogeny of Polychaeta.Based on previous studies,we collated keys to the orders and families of benthic groups of Polychaeta from the coastal waters of China.Additionally,we compiled lists of Polychaeta and discussed the taxonomic diversity and the fauna of Polychaeta in China seas.A molecular phylogenetic analysis of common sternaspids from the Yellow Sea and Bohai Sea was conducted base on COI and 16 S rDNA.The main results were as follows:1.Based on previous results of cladistics analysis,in this study,we collated keys to the orders and families of benthic groups of Polychaeta from the coastal waters of China.Referring to Rouse and Fauchald(1997)system and the WoRMS system,we sorted these benthic groups of Polychaeta into seven orders: Echiuroinea,Scolecida,Spionida,Terebellida,Sabellida,Phyllodocida and Eunicida.We used existing work to compile the keys for the seven orders and their constituent families.Finally,we reviewed domestic studies of coastal polychaetes and discussed the contribution of molecular studies to the development of Polychaeta phylogeny.2.The species list of benthic Polychaeta in China seas(Bohai Sea,Yellow Sea,East China seas and South China Sea)were compiled,and the taxonomic diversity and similarity index in the family and species levels were calculated in this paper.The results revealed that the East China Sea has the maximum average taxonomic distinctness index(93.23),while the minimum was the Bohai Sea(90.56).The maximum variation in taxonomic distinctness index was calculated for the Bohai Sea(277.83)and the East China seas had the minimum(210.45).The composition of species similarity on the species level between the Bohai Sea and the Yellow Sea was the highest(0.486)and the lowest was between the Bohai Sea and the South China seas(0.128).These results indicated that there are obvious differences in benthic Polychaeta biota in China Seas.3.The morphological identification of sternaspid samples collected from the Bohai Sea and Yellow Sea were Sternaspis liui and S.chinensis.The results of molecular phylogenetic study of sternaspid based on datasets of mitochondrial DNA COI and 16 S rDNA showed that S.liui and S.chinensis were highly clustered,which indicated that they might be one species.More studies are needed to determine whether they are one species.